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Sample records for boreal brackish-water conditions

  1. Management of Brackish water for crop production under arid and semi-arid conditions

    International Nuclear Information System (INIS)

    For sustainable crop production, changing soil or water chemistry so as to counter the adverse effects of brackish water is a good option. This is normally accomplished by soil or water applied amendments such as gypsum. The other option of blending or cycling brackish and non-brackish water also has merits to reduce the potential hazards. The biological and organic amendments improve soil physical conditions which, otherwise, are expected to be deteriorated by the use of brackish water. Keeping this in view, a field experiment was conducted on a non saline-non sodic sandy loam soil (EC/sub e/ 1.31-1.76 dS m/sup -1/, pH = 8.47-8.61, SAR = 5.50-7.41, infiltration rate 0.6-0.8 cm/h, bulk density = 1.56-1.61 Mg m/sup -3/ for the upper 15 cm soil depth) to evaluate the growth response of cotton crop to different soil and water treatments. Treatments included: T/sub 1/ canal water), T/sub 2/ [tube well water (EC = 3.38 dS m/sup -1/, SAR = 16.43 and RSC = 5.57 mmol/sub c/ L/sup -1/)], T3 [cyclic use (alternate irrigations with canal and tube well waters)], T/sub 4/ (tube well water as such + FYM at the rate of 25 Mg ha/sup -1/annually) and T/sub 5/ (tube well water + gypsum at the rate of water gypsum requirement (WRSC to be decreased up to 00). During the first year of experimentation seed cotton yield was not significantly affected by the applied treatments and was in the decreasing order of: T/sub 3/ (2361 kg ha/sup -1/) > T/sub 4/ (2073 kg ha/sup -1/) > T 1 (2015 kg ha/sup -1/) > T/sub 5/ (2001 kg ha.1 and T 2 (1982 ha/sup -1/. Number of bolls picked per plant was in the decreasing order of: T 2 (33) > T/sub 4/ (32) > T/sub 1/ (31) > T/sub 3/ (30) and T/sub 5/ (26) with non-significant treatment differences. The pH, EC/sub e/ and SAR values remained below safe limits by this cotton (first) crop. (author)

  2. Biosorption treatment of brackish water

    International Nuclear Information System (INIS)

    Biosorptivity of different agricultural wastes have been evaluated for the treatment of brackish water and a new method, based on the principle of bio-sorption has been described. Wastes of the Saccharum officinarum, Moringa oleifera, Triticum aestivcum and Oryza sativa have been used in raw forms as well as after converting them into ash and activated carbon as biosorbents for treatment of brackish water in this study. Samples of brackish water have been analyzed before and after treatment for quality control parameters of water. A significant Improvement has been observed in quality control parameters of water after treatment. pH of the water samples slightly increased from 7.68 to 7.97 with different treatments. A substantial decrease in conductivity,. TDS, TH, concentrations of cations and anions was observed in the samples of brackish water after treatment with different biosorbents. (author)

  3. Membrane technology comparison in brackish water purification

    OpenAIRE

    Martorell Cebrián, Aleix

    2010-01-01

    This work reviews membrane technologies- specifically Brackish Water Revere Osmosis (BWRO), Nanofiltration (NF) and Electrodyalisis Reversal (EDR), for drinking water production from brackish waters at lab, pilot and industrial scale. In the recent years, many fresh water resources such as surface and groundwater have become overused or misused. As a result, these resources are either diminishing or becoming low quality waters, which are supplied to population due to scarcity. ...

  4. Growing floricultural crops with brackish water

    NARCIS (Netherlands)

    Cassaniti, C.; Romano, D.; Hop, M.E.C.M.; Flowers, T.J.

    2013-01-01

    In the current review we focus on the opportunity to use brackish water in the cultivation of floricultural plants, plants for which, due to their high economic value, growers have traditionally used good quality water for irrigation. Now, even for these crops the use of alternative water sources fo

  5. Infrared Turbidimetric Titration Method for Sulfate Ions in Brackish Water

    OpenAIRE

    Benabadji Nouredine; Kherici Samira; Benouali Djillali

    2012-01-01

    In this work an infrared turbidimetric titration method is described for the determination of sulfate ions in brackish water. A suspension of barium sulfate is produced in an aqueous solution and/or brackish water sample by the addition of barium chloride solution and the turbidity is monitored with the help of an immersed infrared sensor. The developed sensor utilizes an optical system to measure the evolution of turbidity during the titration. This sensor is a simple device designed in th...

  6. Desalting sea water and brackish waters: a cost update

    International Nuclear Information System (INIS)

    This report, based on first-quarter 1977 dollars, is an update of costs presented in ORNL/TM-5070 (Rev.), which gave cost estimates for desalting seawater and brackish waters based on first-quarter 1975 financial parameters. Cost estimates are given for desalting seawater by distillation and reverse osmosis and for brackish waters using reverse osmosis and electrodialysis. Cost data were computed as a function of plant size and energy cost. The cost of generating steam and electrical energy on-site using coal-fired boilers as well as oil-fired boilers and dual-purpose electric/seawater distillation plants is included. While the costs of energy, equipment and labor have continued to rise, they have increased at a relatively modest rate compared with the two years prior to 1975. On an average, the cost of desalting seawater by distillation has increased approximately 15%. Costs for desalting brackish waters by the membrance processes have increased about 7%

  7. Desalting seawater and brackish waters: 1981 cost update

    International Nuclear Information System (INIS)

    This is the fourth in a series of desalting cost update reports. Cost data are reported for desalting seawater by various distillation systems and by reverse osmosis. Costs of desalting four brackish waters, representative of those found in the United States by both reverse osmosis and electrodialysis are also given. Cost data are presented parametrically as a function of energy cost and plant size. The cost of desalting seawater by distillation has increased by 40% during the past two years, while desalting by reverse osmosis has increased by about 36% during the same period. Brackish water desalting by reverse osmosis has only increased by about 12%, and brackish water desalting by electrodialysis is up by 40%. Again, the continued increase in energy costs has had a major impact on all desalination systems

  8. A comparative study of boron and arsenic (III) rejection from brackish water by reverse osmosis membranes

    KAUST Repository

    Teychene, Benoît

    2013-02-01

    This study aims to compare at lab-scale the rejection efficiency of several reverse osmosis membranes (RO) toward arsenic (III) and boron during the filtration of a synthetic brackish water. The effect of pH and operating conditions on the rejection of each RO membrane was studied. Two types of membrane were investigated: "brackish water" and "sea water" membranes. Our results showed that the metalloid rejection depends on the membrane type, pH and transmembrane pressure applied. Increasing pH above the dissociation constant (pKa) of each specie improves significantly the metalloid rejection by RO membranes, whatever the membrane type. Moreover, at identical operating conditions (pH, transmembrane pressure), results showed that the brackish water membranes have a higher water flux and exhibit lower metalloid rejection. The highest As(III) rejection value for the tested brackish water membranes was 99% obtained at pH = 9.6 and 40 bars, whereas it was found that the sea water RO membranes could highly reject As(III), more than 99%, even at low pH and low pressure (pH = 7.6 and 24 bars).Regarding Boron rejection, similar conclusions could be drawn. The sea water RO membranes exert higher removal, with a high rejection value above 96% over the tested conditions. More generally, this study showed that, whatever the operating conditions or the tested membranes, the boron and As(III) permeate concentrations are below the WHO guidelines. In addition, new data about the boron and arsenic permeability of each tested RO membrane was brought thanks to a theoretical calculation. © 2012 Elsevier B.V.

  9. Desalination of underground brackish waters using an electrodialysis system powered directly by photovoltaic energy

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, J.M.; Exposito, E.; Gallud, F.; Garcia-Garcia, V.; Montiel, V.; Aldaz, A. [Grupo de Electroquimica Aplicada y Electrocatalisis, Departamento de Quimica Fisica and Instituto Universitario de Electroquimica, Universidad de Alicante, Ap. 99, 03080 Alicante (Spain)

    2008-12-15

    The aims of this paper are: to demonstrate the feasibility of the desalination of brackish water from aquifers (total dissolved solids=2300-5100 g m{sup -3}) by means of an electrodialysis system powered directly by photovoltaic solar panels, and improve the mathematical model developed in a previous work in order to apply it to real brackish waters. The application of this model allows to predict the behaviour of the electrodialysis-photovoltaic system under different operational and meteorological conditions, and the time required to reach a given final concentration. Finally, the cost of electrodialysis-photovoltaic systems for small applications in isolated locations with lack of electric grid has been estimated. (author)

  10. A study of brackish water membrane with ultrafiltration pretreatment in Indonesia’s coastal area

    Directory of Open Access Journals (Sweden)

    Elis Hastuti

    2012-06-01

    Full Text Available Water pollution and sea water intrusion to water sources in coastal areas result lack of provision safe drinking water by the drinking water regional company or coastal community. The existing water treatment plant that operated on brackish surface water or groundwater feed requires improving process. Membrane process could be a choice to treat the quality of brackish water to the level of potable water that designed to lower cost with high stabil flux and longer lifetime. This research focus on application of pilot plant of brackish water treatment using Ultrafiltration (UF membrane-air lift system as pretreatment of Reverse Osmosis (RO membrane-low pressure. Brackish water sources contain high colloidal and suspended solids that can cause fouling load of RO membranes and impair its performance. UF pretreatment operation tested by addition of compressed air into the feed (air lift system, resulted stable flux, reduces membrane fouling and low feed pressure. A flux of RO with UF pretreatment can produce drinking water of 30–61 L/m2∙hour. It was observed, the good quality of RO permeate resulted by using a pretreatment of UF–PS (Polysulfone-UF with total dissolved solid rejection about 96–98% and color rejection about 99–100% at 5 or 8 bars of operation pressure. This paper concludes that performance of membrane technology with UF–air lift system pretreatment and RO membrane-low pressure could be accepted as condition of brackish water source in Indonesia coastal areas in producing drinking water.

  11. Infrared Turbidimetric Titration Method for Sulfate Ions in Brackish Water

    Directory of Open Access Journals (Sweden)

    Benabadji Nouredine

    2012-12-01

    Full Text Available In this work an infrared turbidimetric titration method is described for the determination of sulfate ions in brackish water. A suspension of barium sulfate is produced in an aqueous solution and/or brackish water sample by the addition of barium chloride solution and the turbidity is monitored with the help of an immersed infrared sensor. The developed sensor utilizes an optical system to measure the evolution of turbidity during the titration. This sensor is a simple device designed in the laboratory, consisting of two infrared diodes (LED, the first is an emitter and the second is used as detector (receiver. The data acquisition system is made with the help of a dataloger made on the basis of the microcontroller 16F877/874 accompanied with adaptable software both of them are self made. Concentration over 60 µg/mL of sulfate expressed as, SO42- can be measured with high reproducibility, by this method without a preliminary treatment or dilution of the sample. The method determines SO42 - concentration of brackish water with RSD of < 1.2%.

  12. Using mesoporous carbon electrodes for brackish water desalination.

    Science.gov (United States)

    Zou, Linda; Li, Lixia; Song, Huaihe; Morris, Gayle

    2008-04-01

    Electrosorptive deionisation is an alternative process to remove salt ions from the brackish water. The porous carbon materials are used as electrodes. When charged in low voltage electric fields, they possess a highly charged surface that induces adsorption of salt ions on the surface. This process is reversible, so the adsorbed salt ions can be desorbed and the electrode can be reused. In the study, an ordered mesoporous carbon (OMC) electrode was developed for electrosorptive desalination. The effects of pore arrangement pattern (ordered and random) and pore size distribution (mesopores and micropores) on the desalination performance was investigated by comparing OMC and activated carbon (AC). It were revealed from X-ray diffraction and N(2) sorption measurements that AC has both micropores and mesopores, whereas ordered mesopores are dominant in OMC. Their performance as potential electrodes to remove salt was evaluated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests at a range of electrolyte concentrations and sweep rates. It is deduced that under the same electrochemical condition the specific capacitance values of OMC electrode (i.e. 133 F/g obtained from CV at a sweep rate of 1 mV/s in 0.1M NaCl solution) are larger than those of AC electrode (107 F/g), suggesting that the former has a higher desalting capacity than the latter. Furthermore, the OMC electrode shows a better rate capacity than the AC electrode. In addition, the desalination capacities were quantified by the batch-mode experiment at low voltage of 1.2V in 25 ppm NaCl solution (50 micros/cm conductivity). It was found that the adsorbed ion amounts of OMC and AC electrodes were 11.6 and 4.3 micromol/g, respectively. The excellent electrosorptive desalination performance of OMC electrode might be not only due to the suitable pore size (average of 3.3 nm) for the propagation of the salt ions, but also due to the ordered mesoporous structure that facilitates desorption of the

  13. Nitrate decontamination through functionalized chitosan in brackish water.

    Science.gov (United States)

    Appunni, Sowmya; Rajesh, Mathur P; Prabhakar, Sivaraman

    2016-08-20

    N, N, N-Triethyl ammonium functionalized cross-linked chitosan beads (TEACCB) was prepared by alkylation of glutaraldehyde cross-linked chitosan beads to remove nitrate from brackish water. Physico-chemical characteristics of TEACCB were analyzed using FTIR, SEM, EDAX, TGA, DTA, BET surface area, swelling ratio and pHzpc. The maximum nitrate removal capacity of TEACCB was 2.26meq/g and is higher than other reported chitosan based adsorbents. Nitrate removal ratio in the presence and absence of common anions like chloride and sulphate demonstrated the selectively of TEACCB towards nitrate. The kinetic data of nitrate removal fitted well with the pseudo-second-order kinetic model. The thermodynamic parameters indicated that nitrate removal could be spontaneous and exothermic in nature. TEACCB was reused with 100% efficiency after regenerating with 0.05N HCl. Column study was carried out to remove nitrate from brackish water. These results are very significant to develop TEACCB based nitrate removal technology with great efficiency. PMID:27178960

  14. Microplankton bloom in a brackish water lagoon of Terengganu.

    Science.gov (United States)

    Shamsudin, L; Shazili, N A

    1991-10-01

    Increased primary plankton productivity was observed in a brackish water lagoon of Terengganu during the study period between January 1988 to December 1988. The lagoon is also the site for the fish cage culture activities of sea bass during the study period. An examination of water quality at the sampling stations during the study period indicated that both the organic and inorganic nutrients were high during the pre-monsoon period. The source of the nutrient in the lagoon was believed to be derived from the agro-based industrial effluents, fertilisers from paddy fields as well as untreated human and animal wastes. This coincided with the peak production of plankton in the surface waters of the brackish water lagoon. During this period both cultured and indigenous fish species were seen to suffer from oxygen asphyxiation (suffocation due to lack of oxygen). The primary productivity values ranged from 9 to 22 μg/L/h during the peak period while the microplankton species were composed of diatom, flagellates and dinoflagellates. Reduction in the primary productivity values were obtained with reduction in sallinity, specially during the peak monsoon months (November to March) corresponding to the Northeast monsoon period. PMID:24233946

  15. Sustainable use of Brackish water for crop production

    International Nuclear Information System (INIS)

    The good quality surface-water is not sufficient to meet the crop water requirement for potential crop production. To augment the inadequate supplies of good quality water the only alternative is the use of poor quality , ground water. To explore sustainable use of brackish water a study was conducted in Fordwah Eastern Sadiqia South, Bahawalnagar, Punjab during the year 1998-99 to 2000-2001 with the objective to evaluate the impact of different irrigation treatments on physical and chemical properties of soil and crops yield. The experiment was conducted on farmer's field with his collaboration. The initial soil pH was about 8.0 while ECe and SAR ranged between 2.0 to 4.1 dS m/sup -/1 and 7.1 to 15.1 (mmol/sub c/ L/sup -1/)1/2, respectively with sandy loam texture. The brackish water used for irrigation had ECiw, SAR and RSC between 5.6 to 6.7 dS m/sup -/1, 15.1 to 16.4 (mmolc L/sup -1/sup 1/2/ and 1.52 to 1.64 (mmol/sub c/ L/sup -1/.The crops tested were wheat during Rabi and cotton during Kharif season. The treatments tested were: irrigation with canal water (T/sub 1/), canal water during Rabi and drainage water during Kharif (T/sub 2/), drainage water for two years and canal water for one season(T/sub 3/); and drainage water for three years + application of gypsum at the rate of 25% of CWR and thereafter canal water for one season(T 4). Fertilizers were applied at the rate of 120-60-50 N, P/sub 2/O/sub 5/ and K20 kg ha/sup -1/, respectively in the form of urea, diammonium phosphate and sulfate of potash. Crops irrigated with drainage water visualized yield reduction depending upon the share of drainage water in the irrigation delta. Application of gypsum provided reasonable check against salinity build-up with brackish water irrigation besides a nominal boost of 3 and 5% in yield of wheat and cotton, respectively over comparable treatment of year-round brackish water irrigation lacking gypsum application. Drainage water in alternate arrangement of seasonal

  16. Desalination of Saline and Brackish Waters using Carbon Aerogel Technology

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Massoudinejad

    2012-10-01

    Full Text Available Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 Background and Objectives: The increasing demand for drinking water has led scientists to the use of saline waters, but existing desalinating processes are very expensive. carbon aerogel is a type of organic aerogel that is suitable for desalination owing to its unique porous structure. Low potential of fouling and deposits, very low wastewater production, electrostatic regeneration of aerogels and, in turn, no need to acid consumption, and lower power consumption are some of this technology benefits.Materials and Method: In this experimental- analytical study, the purpose was survey of saline and brackish water desalination using carbon aerogel technology and its comparison with electrolysis.The community studied was synthetic salt water samples, using of TDS and EC indicators. The minimum synthetic samples were 243. In this regard, after polymerization of Resorsinol and Formaldehyde compounds under ambient pressure conditions and then its pyrolysis, we fabricated plates of carbon aerogel.Result: With manufacturing in the pilot-scale, the effect of different parameters, including input salt concentration, current, water flow, distance of between electrodes and pH, on NaCl sorption amount of carbon aerogel electrodes were studied. Generally, adsorption amount increased with increasing of current and NaCl concentration and decreased with increasing of distance electrodes, flow and pH.  Results: Fabricating reactor at pilot-scale, we studied the effect of different parameters, including input salt concentration, current, water flow, intra-distance of electrodes, and pH on the NaCl sorption using carbon aerogel electrodes. Generally, adsorption capacity increased with increasing of current and NaCl concentration in the inlet flow, and it decreased with increasing intra-distance of electrodes, flow, and pH.Conclusion: Under the most optimal

  17. Radiative characteristics of ice-covered fresh- and brackish-water bodies

    Directory of Open Access Journals (Sweden)

    Leppäranta, Matti

    2006-03-01

    Full Text Available The structure and optics of ice and snow overlying bodies of water were studied in the years 2000–2003. The data were collected in the northern temperate region (nine Estonian and Finnish lakes and one brackish water site, Santala Bay, in the Gulf of Finland. In the present paper we describe the results concerning the radiative characteristics of the system “snow + ice cover on the water”: albedo, attenuation of light, and planar and scalar irradiances through the ice. The basic data consist of irradiance measurements above and below ice cover for the PAR band of the solar spectrum (400–700 nm. Albedo varied across wide limits (0.20–0.70 for ice, 0.63–0.94 for snow, depending on the optical and physical properties of ice/snow and weather conditions. The vertically averaged light attenuation coefficient of the ice layer in the brackish waters of Santala Bay was higher than that in the lakes. The ratio of irradiance beneath the ice to incident irradiance increased 2.5–20 times after removing the snow, depending on the albedo and the thickness of ice and snow as well as on their optical properties. In the upper layer of water beneath the ice the ratio of planar to scalar quantum irradiances increased with depth (according to our earlier results obtained in summer this ratio decreased with increasing depth.

  18. Cellulose Derived Graphenic Fibers for Capacitive Desalination of Brackish Water.

    Science.gov (United States)

    Pugazhenthiran, Nalenthiran; Sen Gupta, Soujit; Prabhath, Anupama; Manikandan, Muthu; Swathy, Jakka Ravindran; Raman, V Kalyan; Pradeep, Thalappil

    2015-09-16

    We describe a simple and inexpensive cellulose-derived and layer-by-layer stacked carbon fiber network electrode for capacitive deionization (CDI) of brackish water. The microstructure and chemical composition were characterized using spectroscopic and microscopic techniques; electrochemical/electrical performance was evaluated by cyclic voltammetry and 4-probe electrical conductivity and surface area by Brunauer-Emmett-Teller analysis, respectively. The desalination performance was investigated using a laboratory batch model CDI unit, under fixed applied voltage and varying salt concentrations. Electro-adsorption of NaCl on the graphite reinforced-cellulose (GrC) electrode reached equilibrium quickly (within 90 min) and the adsorbed salts were released swiftly (in 40 min) back into the solution, during reversal of applied potential. X-ray photoelectron spectroscopic studies clearly illustrate that sodium and chloride ions were physisorbed on the negative and positive electrodes, respectively during electro-adsorption. This GrC electrode showed an electro-adsorption capacity of 13.1 mg/g of the electrode at a cell potential of 1.2 V, with excellent recyclability and complete regeneration. The electrode has a high tendency for removal of specific anions, such as fluoride, nitrate, chloride, and sulfate from water in the following order: Cl->NO3->F->SO4(2-). GrC electrodes also showed resistance to biofouling with negligible biofilm formation even after 5 days of incubation in Pseudomonas putida bacterial culture. Our unique cost-effective methodology of layer-by-layer stacking of carbon nanofibers and concurrent reinforcement using graphite provides uniform conductivity throughout the electrode with fast electro-adsorption, rapid desorption, and extended reuse, making the electrode affordable for capacitive desalination of brackish water. PMID:26305260

  19. [Effects of brackish water irrigation on soil enzyme activity, soil CO2 flux and organic matter decomposition].

    Science.gov (United States)

    Zhang, Qian-qian; Wang, Fei; Liu, Tao; Chu, Gui-xin

    2015-09-01

    Brackish water irrigation utilization is an important way to alleviate water resource shortage in arid region. A field-plot experiment was set up to study the impact of the salinity level (0.31, 3.0 or 5.0 g · L(-1) NaCl) of irrigated water on activities of soil catalase, invertase, β-glucosidase, cellulase and polyphenoloxidase in drip irrigation condition, and the responses of soil CO2 flux and organic matter decomposition were also determined by soil carbon dioxide flux instrument (LI-8100) and nylon net bag method. The results showed that in contrast with fresh water irrigation treatment (CK), the activities of invertase, β-glucosidase and cellulase in the brackish water (3.0 g · L(-1)) irrigation treatment declined by 31.7%-32.4%, 29.7%-31.6%, 20.8%-24.3%, respectively, while soil polyphenoloxidase activity was obviously enhanced with increasing the salinity level of irrigated water. Compared to CK, polyphenoloxidase activity increased by 2.4% and 20.5%, respectively, in the brackish water and saline water irrigation treatments. Both soil microbial biomass carbon and microbial quotient decreased with increasing the salinity level, whereas, microbial metabolic quotient showed an increasing tendency with increasing the salinity level. Soil CO2 fluxes in the different treatments were in the order of CK (0.31 g · L(-1)) > brackish water irrigation (3.0 g · L(-1)) ≥ saline water irrigation (5.0 g · L(-1)). Moreover, CO2 flux from plastic film mulched soil was always much higher than that from no plastic film mulched soil, regardless the salinity of irrigated water. Compared with CK, soil CO2 fluxes in the saline water and brackish water treatments decreased by 29.8% and 28.2% respectively in the boll opening period. The decomposition of either cotton straw or alfalfa straw in the different treatments was in the sequence of CK (0.31 g · L(-1)) > brackish water irrigation (3.0 g · L(-1)) > saline water treatment (5.0 g · L(-1)). The organic matter

  20. Desalination of brackish water and concentration of industrial effluents by electrodialysis

    OpenAIRE

    J. J. Schoeman; G. R. Botha

    1983-01-01

    Electrodialysis (ED) is, at present, used mainly for the desalination of brackish drinking-water. Brackish water with a high scaling potential can be successfully treated, using the electrodialysis reversal (EDR) process without the addition of chemicals. The reliability of the ED process makes it very attractive for water treatment. Although used mainly for brackish water desalination, ED also has certain industrial applications. Plating wash waters, cooling tower recirculation water and gla...

  1. High Recovery Desalination of Brackish Water by Chemically-Enhanced Seeded Precipitation

    OpenAIRE

    McCool, Brian Carey

    2012-01-01

    Various regions around the world are confronted with dwindling water supplies and thus the need for exploiting non-traditional inland brackish water resource, as well as reclamation and reuse of municipal wastewater and agricultural drainage (AD) water. Reverse osmosis (RO) membrane desalination is the primary technology for inland brackish water desalting. However, successful implementation of RO technology requires operation at high product water recovery (>85%) in order to minimize the vol...

  2. Influence of nutrient input on the trophic state of a tropical brackish water lagoon

    Indian Academy of Sciences (India)

    D Ganguly; Sivaji Patra; Pradipta R Muduli; K Vishnu Vardhan; Abhilash K R; R S Robin; B R Subramanian

    2015-07-01

    Ecosystem level changes in water quality and biotic communities in coastal lagoons have been associated with intensification of anthropogenic pressures. In light of incipient changes in Asia’s largest brackish water lagoon (Chilika, India), an examination of different dissolved nutrients distribution and phytoplankton biomass, was conducted through seasonal water quality monitoring in the year 2011. The lagoon showed both spatial and temporal variation in nutrient concentration, mostly altered by fresh-water input, regulated the chlorophyll distribution as well. Dissolved inorganic N:P ratio in the lagoon showed nitrogen limitation in May and December, 2011. Chlorophyll in the lagoon varied between 3.38 and 17.66 mg m−3. Spatially, northern part of the lagoon showed higher values of DIN and chlorophyll during most part of the year, except in May, when highest DIN was recorded in the southern part. Statistical analysis revealed that dissolved NH$^{+}_{4}$–N and urea could combinedly explain 43% of Chlorophyll- (Chl-) variability which was relatively higher than that explained by NO$^{-}_{3}$–N and NO$^{-}_{2}$–N (12.4%) in lagoon water. Trophic state index calculated for different sectors of the lagoon confirmed the inter-sectoral and inter-seasonal shift from mesotrophic to eutrophic conditions largely depending on nutrient rich freshwater input.

  3. Influence of nutrient input on the trophic state of a tropical brackish water lagoon

    Science.gov (United States)

    Ganguly, D.; Patra, Sivaji; Muduli, Pradipta R.; Vardhan, K. Vishnu; R, Abhilash K.; Robin, R. S.; Subramanian, B. R.

    2015-07-01

    Ecosystem level changes in water quality and biotic communities in coastal lagoons have been associated with intensification of anthropogenic pressures. In light of incipient changes in Asia's largest brackish water lagoon (Chilika, India), an examination of different dissolved nutrients distribution and phytoplankton biomass, was conducted through seasonal water quality monitoring in the year 2011. The lagoon showed both spatial and temporal variation in nutrient concentration, mostly altered by freshwater input, regulated the chlorophyll distribution as well. Dissolved inorganic N:P ratio in the lagoon showed nitrogen limitation in May and December, 2011. Chlorophyll in the lagoon varied between 3.38 and 17.66 mg m -3. Spatially, northern part of the lagoon showed higher values of DIN and chlorophyll during most part of the year, except in May, when highest DIN was recorded in the southern part. Statistical analysis revealed that dissolved NH-N and urea could combinedly explain 43% of Chlorophyll- a (Chl- a) variability which was relatively higher than that explained by NO-N and NO-N (12.4%) in lagoon water. Trophic state index calculated for different sectors of the lagoon confirmed the inter-sectoral and inter-seasonal shift from mesotrophic to eutrophic conditions largely depending on nutrient rich freshwater input.

  4. Osmoregulatory adaptations of freshwater air-breathing snakehead fish (Channa striata) after exposure to brackish water.

    Science.gov (United States)

    Nakkrasae, La-iad; Wisetdee, Khanitha; Charoenphandhu, Narattaphol

    2015-07-01

    NaCl-rich rock salt dissolved in natural water source leads to salinity fluctuation that profoundly affects freshwater ecosystem and aquatic fauna. The snakehead (Channa striata) can live in saline water, but the osmoregulatory mechanisms underlying this ability remain unclear. Herein, we found that exposure to salinities ≥ 10‰ NaCl markedly elevated plasma cortisol and glucose levels, and caused muscle dehydration. In a study of time-dependent response after being transferred from fresh water (0‰ NaCl, FW) to salt-dissolved brackish water (10‰ NaCl, SW), FW-SW, cortisol increased rapidly along with elevations of plasma glucose and lactate. Interestingly, plasma cortisol returned to baseline after prolonged exposure, followed by a second peak that probably enhanced the branchial Na(+)/K(+)-ATPase activity. Under SW-FW condition, Na(+)/K(+)-ATPase activity was not altered as compared to SW-adapted fish. In conclusion, salinity change, especially FW-SW, induced a stress response and hence cortisol release in C. striata, which might increase plasma glucose and lactate to energize the branchial Na(+)/K(+)-ATPase. PMID:25899744

  5. Uptake and effects of americium-241 on a brackish-water amphipod

    International Nuclear Information System (INIS)

    The present paper reports the results of experimental work undertaken using the brackish-water amphipod Gammarus duebeni duebeni and the transuranium nuclide americium-241. Data on the accumulation of this actinide showed that the larger fraction of the total body burden is associated with the exoskeleton. It was found that the body burden remained constant in the range pH 8.0-6.5 even though the water concentration changed markedly. It would thus appear that the concept of a concentration factor should be re-examined and it is proposed that a factor should be defined in terms of environmental and chemical parameters which represent the bioavailable fraction of the actinide. The effect of americium on survival and moulting was studied at two activity concentrations; the dose rates and absorbed doses under the experimental conditions employed have been estimated. The differences in survival rates between the control and irradiated groups were statistically analyzed and the significant difference at the higher concentration is believed to be due to a synergism between physiological stress and radiotoxicity of americium rather than the chemical toxicity of the element. (orig.)

  6. Desalination of brackish water and concentration of industrial effluents by electrodialysis

    Directory of Open Access Journals (Sweden)

    J. J. Schoeman

    1983-03-01

    Full Text Available Electrodialysis (ED is, at present, used mainly for the desalination of brackish drinking-water. Brackish water with a high scaling potential can be successfully treated, using the electrodialysis reversal (EDR process without the addition of chemicals. The reliability of the ED process makes it very attractive for water treatment. Although used mainly for brackish water desalination, ED also has certain industrial applications. Plating wash waters, cooling tower recirculation water and glass etching effluents have been treated successfully with ED for water recovery and effluent volume reduction, while ED treatment of nickel plating wash waters is an established industrial process.

  7. Epiphytic bacterial community composition on two common submerged macrophytes in brackish water and freshwater

    OpenAIRE

    Blindow Irmgard; Blume Maja; Hempel Melanie; Gross Elisabeth M

    2008-01-01

    Abstract Background Plants and their heterotrophic bacterial biofilm communities possibly strongly interact, especially in aquatic systems. We aimed to ascertain whether different macrophytes or their habitats determine bacterial community composition. We compared the composition of epiphytic bacteria on two common aquatic macrophytes, the macroalga Chara aspera Willd. and the angiosperm Myriophyllum spicatum L., in two habitats, freshwater (Lake Constance) and brackish water (Schaproder Bodd...

  8. Effects of plant diversity on primary production and species interactions in brackish water angiosperm communities

    DEFF Research Database (Denmark)

    Salo, Tiina; Gustafsson, Camilla; Boström, Christoffer

    2009-01-01

    plant productivity in brackish water angiosperm communities, a 14 wk field experiment was conducted. Using a replacement design with a standardized initial aboveground biomass, shoots of Zostera marina, Potamogeton filiformis and P. perfoliatus were planted on a shallow, sandy bottom in replicated...

  9. Tunisian brackish water desalination by Electrodialysis : Opposing scaling and process optimization

    International Nuclear Information System (INIS)

    Electrodialysis (ED) did not know a mattering development in the desalination field because of problems usually related to energy consumption, the scaling and/or precipitation phenomenon of certain mineral salts (CaSO4, CaCO3, etc.). and the importance of investments which they require. So, to mitigate some of these problems and to increase the electrodialysis processes potentialities, we introduced a crystallisation inhibitor (sodium polyacrylate RPI2000) into the concentration compartment during Ed's operations. Then we studied some parameters such as the applied potential or the circulation flow of studied solutions. The inhibitor addition allowed to delay the precipitation in the ED concentration comportment, confining so the brine in a small volume and decrease the frequency of replacement of membranes, which will reduce the cost of the process. Without adding scaling inhibitors, a set of experiment was performed using synthetic water supersaturated on CaCO3 and CaSO4 at room temperature. Several flows rates are tested (80, 60, 40 and 30 L/h). We applied 20 V until the conductivity measured in the dilute compartment dropped approximately from 9000 =μS/cm to 1500 μS/cm. We used the same concentrate solution to treat many synthetic water volumes. The results showed us that more the flow is important more the phenomenon of scaling is delayed. In order to increase the performance of the electrodialysis process we applied a pulsed electric field with different duty cycle (Ton = Toff = 1, 3, 10 and 30 seconds). Then, we compare conductivity evolution in the dilute as a function of the pulse mode. The results shows a faster decrease of the concentration in the dilute under pulsed field conditions. Pulsed electric field electrodialysis seems to be very promising for future development in brackish water desalination, to some extent it can remove some well known limitations of electrodialysis. Experiments on desalination of brackish water by pulse field

  10. On brackish water desalination economics and alternative renewable energies in Mena countries

    International Nuclear Information System (INIS)

    Nowadays, water management in MENA, no longer exclusive to a sectoral issue pertaining to engineering and technical expertise such as irrigation, water supply and water storage, becomes a shared developmental challenge. In order to face an increasingly growing water crisis, attention on balancing the supply and demand for water given the current constraints, needs analysis of conventional and non conventional water resources from a range of perspectives, including considerations about technological dynamics and alternative renewable energies, which are highly recommended. Thanks to engaged technical progress enabling sensitive desalination cost reduction, water crisis could be of lower impacts. For this region being the world leader in desalination technology investments, we are obliged to rexamine the characteristics of alternative renewable energies. To prevent water shortage from being a constraint to economic development and social stability in MENA, we argue brackish water desalination as one of the most promising and viable options, notably in long term for future generations. This paper contains four sections. brackish water characteristics are clarified in section 1. Then in section 2, we focus on factors affecting both desalination costs and desalination implementation costs. A particular attention is spent in section 3 to electro-dialysis reverse (EDR), subsequent capital and O and M costs approximations. Besides, since there is a pressing need for brackish water desalination, which is energy intensive, alternative renewable energies related to desalination technologies are hightlighted in section 4.

  11. Environmental conditions of boreal springs explained by capture zone characteristics

    Science.gov (United States)

    Rossi, Pekka M.; Marttila, Hannu; Jyväsjärvi, Jussi; Ala-aho, Pertti; Isokangas, Elina; Muotka, Timo; Kløve, Bjørn

    2015-12-01

    Springs are unique ecosystems, but in many cases they are severely threatened and there is an urgent need for better spring management and conservation. To this end, we studied water quality and quantity in springs in Oulanka National Park, north-east Finland. Multivariate statistical methods were employed to relate spring water quality and quantity to hydrogeology and land use of the spring capture zone. This revealed that most springs studied were affected by locally atypical dolostone-limestone bedrock, resulting in high calcium, pH, and alkalinity values. Using Ward's hierarchical clustering, the springs were grouped into four clusters based on their water chemistry. One cluster consisted of springs affected by past small-scale agriculture, whereas other clusters were affected by the variable bedrock, e.g., springs only 1 km from the dolostone-limestone bedrock area were beyond its calcium-rich impact zone. According to a random forest model, the best predictors of spring water chemistry were spring altitude and the stable hydrogen isotope ratio of the water (δ2H). Thus stable water isotopes could be widely applicable for boreal spring management. They may also provide a rough estimate of groundwater flow route (i.e., whether it is mainly local or regional), which largely determines the chemical characteristics of spring water. Our approach could be applied in other boreal regions and at larger spatial scales for improved classification of springs and for better targeted spring management.

  12. Ascorbic Acid Biosynthesis and Brackish Water Acclimation in the Euryhaline Freshwater White-Rimmed Stingray, Himantura signifer

    OpenAIRE

    Wong, Samuel Z. H.; Ching, Biyun; Chng, You R.; Wong, Wai P.; Chew, Shit F.; Ip, Yuen K.

    2013-01-01

    L-gulono-γ-lactone oxidase (Gulo) catalyzes the last step of ascorbic acid biosynthesis, which occurs in the kidney of elasmobranchs. This study aimed to clone and sequence gulonolactone oxidase (gulo) from the kidney of the euryhaline freshwater stingray, Himantura signifer, and to determine the effects of acclimation from freshwater to brackish water (salinity 20) on its renal gulo mRNA expression and Gulo activity. We also examined the effects of brackish water acclimation on concentration...

  13. Remote sensing of interannual boreal forest NDVI in relation to climatic conditions in interior Alaska

    Science.gov (United States)

    Verbyla, David

    2015-12-01

    Climate has warmed substantially in interior Alaska and several remote sensing studies have documented a decadal-scale decline in the normalized difference vegetation index (NDVI) termed a ‘browning trend’. Reduced summer soil moisture due to changing climatic factors such as earlier springs, less snowpack, and summer drought may reduce boreal productivity and NDVI. However, the relative importance of these climatic factors is poorly understood in boreal interior Alaska. In this study, I used the remotely sensed peak summer NDVI as an index of boreal productivity at 250 m pixel size from 2000 to 2014. Maximum summer NDVI was related to last day of spring snow, early spring snow water equivalent (SWE), and a summer moisture index. There was no significant correlation between early spring SWE and peak summer NDVI. There was a significant correlation between the last day of spring snow and peak summer NDVI, but only for a few higher elevation stations. This was likely due to snowmelt occurring later at higher elevations, thus having a greater effect on summer soil moisture relative to lower elevation sites. For most of boreal interior Alaska, summer drought was likely the dominant control on peak summer NDVI and this effect may persist for several years. Peak summer NDVI declined at all 26 stations after the 2004 drought, and the decline persisted for 2 years at all stations. Due to the shallow rooting zone of most boreal plants, even cool and moist sites at lower elevations are likely vulnerable to drought. For example the peak summer NDVI response following the 2004 drought was similar for adjacent cold and warm watershed basins. Thus, if frequent and severe summer droughts continue, moisture stress effects are likely to be widespread and prolonged throughout most of interior boreal Alaska, including relatively cool, moist sites regardless of spring snowpack conditions or spring phenology.

  14. Ascorbic Acid Biosynthesis and Brackish Water Acclimation in the Euryhaline Freshwater White-Rimmed Stingray, Himantura signifer.

    Directory of Open Access Journals (Sweden)

    Samuel Z H Wong

    Full Text Available L-gulono-γ-lactone oxidase (Gulo catalyzes the last step of ascorbic acid biosynthesis, which occurs in the kidney of elasmobranchs. This study aimed to clone and sequence gulonolactone oxidase (gulo from the kidney of the euryhaline freshwater stingray, Himantura signifer, and to determine the effects of acclimation from freshwater to brackish water (salinity 20 on its renal gulo mRNA expression and Gulo activity. We also examined the effects of brackish water acclimation on concentrations of ascorbate, dehydroascorbate and ascorbate + dehydroascorbate in the kidney, brain and gill. The complete cDNA coding sequence of gulo from the kidney of H. signifer contained 1323 bp coding for 440 amino acids. The expression of gulo was kidney-specific, and renal gulo expression decreased significantly by 67% and 50% in fish acclimated to brackish water for 1 day and 6 days, respectively. There was also a significant decrease in renal Gulo activity after 6 days of acclimation to brackish water. Hence, brackish water acclimation led to a decrease in the ascorbic acid synthetic capacity in the kidney of H. signifer. However, there were significant increases in concentrations of ascorbate and ascorbate + dehydroascorbate in the gills (after 1 or 6 days, and a significant increase in the concentration of ascorbate and a significant decrease in the concentration of dehydroascorbate in the brain (after 1 day of fish acclimated to brackish water. Taken together, our results indicate that H. signifer might experience greater salinity-induced oxidative stress in freshwater than in brackish water, possibly related to its short history of freshwater invasion. These results also suggest for the first time a possible relationship between the successful invasion of the freshwater environment by some euryhaline marine elasmobranchs and the ability of these elasmobranchs to increase the capacity of ascorbic acid synthesis in response to hyposalinity stress.

  15. Ascorbic Acid Biosynthesis and Brackish Water Acclimation in the Euryhaline Freshwater White-Rimmed Stingray, Himantura signifer.

    Science.gov (United States)

    Wong, Samuel Z H; Ching, Biyun; Chng, You R; Wong, Wai P; Chew, Shit F; Ip, Yuen K

    2013-01-01

    L-gulono-γ-lactone oxidase (Gulo) catalyzes the last step of ascorbic acid biosynthesis, which occurs in the kidney of elasmobranchs. This study aimed to clone and sequence gulonolactone oxidase (gulo) from the kidney of the euryhaline freshwater stingray, Himantura signifer, and to determine the effects of acclimation from freshwater to brackish water (salinity 20) on its renal gulo mRNA expression and Gulo activity. We also examined the effects of brackish water acclimation on concentrations of ascorbate, dehydroascorbate and ascorbate + dehydroascorbate in the kidney, brain and gill. The complete cDNA coding sequence of gulo from the kidney of H. signifer contained 1323 bp coding for 440 amino acids. The expression of gulo was kidney-specific, and renal gulo expression decreased significantly by 67% and 50% in fish acclimated to brackish water for 1 day and 6 days, respectively. There was also a significant decrease in renal Gulo activity after 6 days of acclimation to brackish water. Hence, brackish water acclimation led to a decrease in the ascorbic acid synthetic capacity in the kidney of H. signifer. However, there were significant increases in concentrations of ascorbate and ascorbate + dehydroascorbate in the gills (after 1 or 6 days), and a significant increase in the concentration of ascorbate and a significant decrease in the concentration of dehydroascorbate in the brain (after 1 day) of fish acclimated to brackish water. Taken together, our results indicate that H. signifer might experience greater salinity-induced oxidative stress in freshwater than in brackish water, possibly related to its short history of freshwater invasion. These results also suggest for the first time a possible relationship between the successful invasion of the freshwater environment by some euryhaline marine elasmobranchs and the ability of these elasmobranchs to increase the capacity of ascorbic acid synthesis in response to hyposalinity stress. PMID:23825042

  16. Selective demineralization of water by nanofiltration application to the defluorination of brackish water.

    Science.gov (United States)

    Lhassani, A; Rumeau, M; Benjelloun, D; Pontie, M

    2001-09-01

    Nanofiltration is generally used to separate monovalent ions from divalent ions, but it is also possible to separate ions of the same valency by careful application of the transfer mechanisms involved. Analysis of the retention of halide salts reveals that small ions like fluoride are the best retained, and that this is even more marked under reduced pressure when selectivity is greatest. The selectivity desalination of fluorinated brackish water is hence feasible and drinking water can be produced directly at much lower cost than using reverse osmosis by optimizing the pressure for the type of water treated. PMID:11487124

  17. A New Turbidimetric method for the Determination of Sulphate in Brackish Waters

    Directory of Open Access Journals (Sweden)

    J. C. Chaudhuri

    1965-01-01

    Full Text Available A New turbidimetric method for the determination of sulphate in brackish waters is described. A suspension of barium sulphate is product in an acidified medium of glycerine d-glucose solution by the addition of barium chloride solution and the turbidity measured with the help of Bausch & Lomb Spectronic '20' Colorimeter. Concentrations upto 160 ppm of sulphate, mate ions do not interfere, nor do Cu/Sup2+, Fe/Sup3+, Co/Sup2+, Ni/Sup2+, and Cr/Sup3+. The method has been applied to the determination of sulphate in desert soils as well.

  18. Radiative characteristics of ice-covered fresh- and brackish-water bodies

    OpenAIRE

    Leppäranta, Matti; Erm, Ants; Arst, Helgi; Reinart, Anu

    2006-01-01

    The structure and optics of ice and snow overlying bodies of water were studied in the years 2000–2003. The data were collected in the northern temperate region (nine Estonian and Finnish lakes and one brackish water site, Santala Bay, in the Gulf of Finland). In the present paper we describe the results concerning the radiative characteristics of the system “snow + ice cover on the water”: albedo, attenuation of light, and planar and scalar irradiances through the ice. The basic data consist...

  19. Lettuce growth and water consumption in NFT hydroponic system using brackish water

    OpenAIRE

    Hammady R. Soares; Ênio F. de F. e Silva; Gerônimo F. da Silva; Pedrosa, Elvira M. R.; Mario M. Rolim; Alexandre N. Santos

    2015-01-01

    The qualitative aspects of water, such as the preparation or replenishment of the nutrient solution, are critical to the success of hydroponic crops. Therefore, the aim of this study was to evaluate the behavior of “Americana” lettuce (cv. Tainá) under increasing levels of saline stress (0.2 - control, 1.2, 2.2, 3.2, 4.2 and 5.2 dS m-1), replenishing the evapotranspiration with brackish water in Experiment I and supply water (0.2 dS m-1) in Experiment II, both used in the preparation of the n...

  20. Frequency of recirculation of nutrient solution in hydroponic cultivation of coriander with brackish water

    OpenAIRE

    Mairton G. da Silva; Tales M. Soares; Hans R. Gheyi; Itamar de S. Oliveira; José A. da Silva Filho; Francicleiton F. do Carmo

    2016-01-01

    ABSTRACT The present study used a hydroponic system with leveled channels, in order to evaluate coriander cultivation under different intervals of nutrient solution recirculation and the use of freshwater and brackish water. The experiment was carried out in a randomized block design with five replicates, in a 2 x 4 factorial scheme, from February to March 2014. Two levels of electrical conductivity (EC) of water (0.32 and 4.91 dS m-1) and four frequencies of nutrient solution recirculation (...

  1. Performance analysis of functioned brackish water for lighting-induced evaporation type solar desalination system%聚光蒸发式太阳能苦咸水淡化系统水体光热性能分析

    Institute of Scientific and Technical Information of China (English)

    侯静; 杨桔材; 郑宏飞; 常泽辉; 于苗苗; 马元波

    2015-01-01

    tested in dish type concentrating system under actual weather condition. The objective of the work was to determine the influence of abundance and size of particles on the optical and thermal performance of the system. The variations of transmissivity for brackish water through different optical paths were recorded under the same conditions. The dish type concentrating solar desalination device was then constructed according to the optical analysis results. The characteristics of temperature and performance ratio(PR) of the water were obtained through outdoor experiment. A dimensionless parameter of “efficiency rate” was used in this paper to evaluate the extinction performance of the functioned brackish water (30-60℃).The results indicated that functioned water could be obtained through adding black particles in brackish water. In addition, the transmissivity of the functioned brackish water decreased with the increasing of abundance, and with the decreasing of particle size. With the smallest particle size of 0.72 mm used in the experiment, the transparency rate of the brackish water reached the lowest value, and the transmissivities through 2 different optical paths decreased by 75.83% and 77.08%, respectively. When the particle abundance increased from 6.25 to 50.00 mg/L, the increase rate of thermal energy utilization efficiency of the functioned brackish water could reach 41.3%. Finally, it was found that the trend of thermal energy utilization efficiency was consistent with the transmissivity.%针对太阳能苦咸水淡化系统中太阳能集热系统在高温段时效率低,而苦咸水淡化系统在低温段时效率低的结构性不匹配问题,提出了聚光蒸发式太阳能苦咸水淡化系统。为了提高苦咸水对入射太阳光的吸收作用,对太阳能集热系统中的苦咸水进行功能化处理,并对功能化苦咸水的透射率进行了光学性能分析,在实际天气条件下,对功能化苦咸水的热能

  2. Influence of dispersants on petroleum bioavailability to primary producers in a brackish water food chain

    Energy Technology Data Exchange (ETDEWEB)

    Younghans-Haug, C.O.; Wolfe, M.F.; Tjeerdema, R.S. [Univ. of California, Santa Cruz, CA (United States). Dept. of Chemistry and Biochemistry; Sowby, M.L. [Office of Oil Spill Prevention and Response, Sacramento, CA (United States)

    1994-12-31

    Petroleum is transported and processed within biologically rich brackish environments worldwide. Past research has investigated disposition of chemically dispersed oil in mammals, fish, and higher invertebrates, yet little is known about how chemical dispersion influences petroleum behavior within primary producers within brackish water food chains. One concern is whether chemical dispersion influences petroleum bioavailability to primary producers and the potential for increased petroleum bioaccumulation. This research examines changes in petroleum bioavailability to the euryhaline phytoplankton Isochrysis galbana by measuring bioconcentration factors (BCFS) including uptake and deputation rates for dispersed and undispersed brackish water oil spills. Isochrysis is a major food source for zooplankton which are consumed by a multitude of larval fish having both ecological and commercial importance. Prudhoe Bay Crude oil, Corexit 9527, and {sup 14}C-naphthalene were used for these studies. Constant-concentration flow-through exposures were employed for the uptake and BCF experiments. Work was performed below the ``no observable effect concentration`` to eliminate stress-induced metabolic altercations that could in themselves influence petroleum behavior. Exposure chamber and experimental design will be discussed, and study results presented. Understanding how chemical dispersion alters petroleum behavior within the lowest levels of the food chain leads to better delineation of consumer risks.

  3. Artificial recharge to a freshwater-sensitive brackish-water sand aquifer, Norfolk, Virginia

    Science.gov (United States)

    Brown, Donald L.; Silvey, William Dudley

    1977-01-01

    Fresh water was injected into a brackish-water sand for storage and retrieval. The initial injection rate of 400 gpm decreased to 70 gpm during test 3. The specific capacity of the well decreased also, from 15.4 to 0.93 gpm. Current-meter surveys indicated uniform reduction in hydraulic conductivity of all contributing zones in the aquifer. Hydraulic and chemical data indicate this was caused by dispersion of the interstitial clay upon introduction of the calcium bicarbonate water into the sodium chloride bearing sand aquifer. The clay dispersion also caused particulate rearrangement and clogging of well screen. A pre-flush of 0.2 N calcium chloride solution injected in front of the fresh water at the start of test 4 stabilized the clay. However, it did not reverse the particulate clogging that permanently reduced permeability and caused sanding during redevelopment. Clogging can be prevented by stabilization of the clay using commercially available trivalent aluminum compounds. Test 1 and test 2 showed that 85 percent of the water injected can be recovered, and the water meets U.S. Public Health Standards. Storage of fresh water in a brackish-water aquifer appears feasible provided proper control measures are used. (Woodard-USGS)

  4. Economic impacts of carbon sequestration in reforestation: examples from boreal and moist tropical conditions.

    OpenAIRE

    Niskanen, Anssi; Saastamoinen, Olli; Rantala, Tapio

    1996-01-01

    Part I Climate Change The impact of carbon sequestration on the financial profitability of four tree plantation cases in Finland and the Philippines were examined. On the basis of stem wood growth; the accumulation of carbon in forest biomass, the formation and decomposition of litter, and the carbon flows in wood-based products were assessed for each reforestation case representing boreal (Finland) and moist tropical conditions (the Philippines). Using different unit values for carbon seq...

  5. Microbially influenced corrosion in cooling water systems. Development of a new protection concept for system components conveying brackish water

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, Simone; Richter, Tobias [E.ON Kernkraft GmbH, Brokdorf Nuclear Power Plant, Brokdorf (Germany); Nowak, Erika [E.ON Kernkraft GmbH, Hannover (Germany)

    2009-07-01

    Corrosive findings ascribed to microbially influenced corrosion (MIC), have been increasingly observed on cooling water systems in Northern German nuclear power plants. By means of a research programme (field tests), high-alloyed materials with different pitting resistance equivalent numbers (PREN), various surface finishing and various coatings were evaluated, based on microbiological preliminary research, with respect to their corrosion behaviour in natural brackish water. Subsequent material evaluations, in combination with other measures, provided a new standard of knowledge for the development of a protection concept for components conveying brackish water. (orig.)

  6. Anopheles culicifacies breeding in brackish waters in Sri Lanka and implications for malaria control

    Directory of Open Access Journals (Sweden)

    Surendran Sinnathamby N

    2010-04-01

    Full Text Available Abstract Background Anopheles culicifacies is the major vector of both falciparum and vivax malaria in Sri Lanka, while Anopheles subpictus and certain other species function as secondary vectors. In Sri Lanka, An. culicifacies is present as a species complex consisting of species B and E, while An. subpictus exists as a complex of species A-D. The freshwater breeding habit of An. culicifacies is well established. In order to further characterize the breeding sites of the major malaria vectors in Sri Lanka, a limited larval survey was carried out at a site in the Eastern province that was affected by the 2004 Asian tsunami. Methods Anopheline larvae were collected fortnightly for six months from a brackish water body near Batticaloa town using dippers. Collected larvae were reared in the laboratory and the emerged adults were identified using standard keys. Sibling species status was established based on Y-chromosome morphology for An. culicifacies larvae and morphometric characteristics for An. subpictus larvae and adults. Salinity, dissolved oxygen and pH were determined at the larval collection site. Results During a six month study covering dry and wet seasons, a total of 935 anopheline larvae were collected from this site that had salinity levels up to 4 parts per thousand at different times. Among the emerged adult mosquitoes, 661 were identified as An. culicifacies s.l. and 58 as An. subpictus s.l. Metaphase karyotyping of male larvae showed the presence of species E of the Culicifacies complex, and adult morphometric analysis the presence of species B of the Subpictus complex. Both species were able to breed in water with salinity levels up to 4 ppt. Conclusions The study demonstrates the ability of An. culicifacies species E, the major vector of falciparum and vivax malaria in Sri Lanka, to oviposit and breed in brackish water. The sibling species B in the An. subpictus complex, a well-known salt water breeder and a secondary malaria

  7. COMPOSITIONAL PROPERTIES OF THREE FRESHWATER CARP SPECIES GROWN IN BRACKISH WATER

    Directory of Open Access Journals (Sweden)

    Muhammad Ismail Chughtai

    2015-06-01

    Full Text Available Three freshwater fish species viz. Labeo rohita, Cirrhinus mrigala and Gibelion catla, grown in brackish water ponds were analyzed for compositional properties to assess the potential of this habitat to produce nutritionally adequate fish for human consumption. Overall, the unsaturated fatty acids were lower in L. rohita (46.6% than saturated fatty acids; while in C. mrigala and G. catla, the unsaturated fatty acids were 50.4% and 58.2%, respectively. The most abundant saturated fatty acid in examined species was palmitic acid (C16:0, 23.7 to 34.1%; mono-unsaturated fatty acid was oleic acid (C18:1 19.6 to 31.7% and poly-unsaturated fatty acid linoleic acid (C18:2 9.46 to 13.3%. A reasonable amount of essential fatty acids ω-3 (5.80 to 9.26% and ω-6 (9.46 to 13.3% was also found in these species while growing in brackish water on salt tolerant forages like Leptochloa fusca, Brachiaria mutica and Kochia indica as supplemental feed. The ω-3/ω-6 ratio was calculated as 0.46, 0.80 and 0.69 in L. rohita, C. mrigala and G. catla, respectively. The maximum EPA (eicosapentaenoic acid, C20:5 was observed in C. mrigala (2.23%, followed by G. catla (1.62% and L. rohita (0.98%. While the DHA (docosahexanenoic acids, C22:6 was found maximum in G. catla (1.97% and minimum in C. mrigala (0.95%. The results of body composition indicated that L. rohita found maximum protein contents (19.2% with minimum total fats (1.28% while C. mrigala found maximum total fats (2.11% but minimum protein contents (18.3%. Overall results indicated that the Indian carps grown in brackish water have comparable chemical composition and nutritive value with the same species grown in freshwater medium.

  8. Development of a sensor for the detection ofEscherichia coli in brackish waters

    Institute of Scientific and Technical Information of China (English)

    Mancuso Monique; Grossi Marco; Rappazzo Alessandro Ciro; Zaccone Renata; Caruso Gabriella; Ricc Bruno; Bergamasco Alessandro

    2016-01-01

    Monitoring of bacterial pathogens is important for marine environmental protection, because the presence of these microorganisms can be a serious risk for human health. For this reason, a portable sensor implemented as an electronic embedded system featuring disposable measurement cells was used to evaluate the ability and sensitivity of detection ofEscherichia coli (E. coli) as an indicator of fecal pollution in transitional environments and a water sample added withE. coli (102CFU/mL) was assayed. The first result obtained from the laboratory experiment seems promising for the determination ofE. coli in environmental samples, though further improvements will be needed for the field application of this sensor in marine and brackish waters.

  9. Development of a sensor for the detection of Escherichia coli in brackish waters

    Directory of Open Access Journals (Sweden)

    Mancuso Monique

    2016-03-01

    Full Text Available Monitoring of bacterial pathogens is important for marine environmental protection, because the presence of these microorganisms can be a serious risk for human health. For this reason, a portable sensor implemented as an electronic embedded system featuring disposable measurement cells was used to evaluate the ability and sensitivity of detection of Escherichia coli (E. coli as an indicator of fecal pollution in transitional environments and a water sample added with E. coli (102 CFU/mL was assayed. The first result obtained from the laboratory experiment seems promising for the determination of E. coli in environmental samples, though further improvements will be needed for the field application of this sensor in marine and brackish waters.

  10. Fecundity regulation in relation to habitat utilisation of two sympatric flounder (Platichtys flesus) populations in the brackish water Baltic Sea

    Science.gov (United States)

    Nissling, Anders; Thorsen, Anders; da Silva, Filipa F. G.

    2015-01-01

    Two populations of flounder (Platichtys flesus) with different life history traits inhabit the brackish water Baltic Sea. Both types share feeding areas in coastal waters during summer-autumn but utilise different habitats for spawning in spring, namely offshore spawning with pelagic eggs and coastal spawning with demersal eggs respectively. Fecundity regulation by atresia was assessed as prevalence (portion of fish with atresia) and intensity (calculated as the average intensity of atresia in these fish) during the reproductive cycle following start of gonad development in the autumn up to spawning in spring, and evaluated in relation to fish condition (Fulton's condition factor reflecting energy reserves of the fish) and feeding incidence of the respective population. Peaking in winter (December-February), fecundity regulation was significantly higher for coastal spawning flounder than for flounder spawning offshore. For coastal spawners, the prevalence was 45-90% with an intensity of 6.4-9.3% vs. 0-25% and an intensity of 2.1-3.4% for offshore spawners during winter. Further, fecundity regulation ceased prior to spawning for offshore spawners but continued for coastal spawners. For coastal spawners, the prevalence was 12-29% and an intensity of 2.5-6.1% during spawning. The change in fish condition was strongly related to feeding incidence and differed between populations. As feeding ceased, condition of offshore spawners decreased during winter up to spawning, whereas condition of coastal spawners decreased during autumn but was maintained as feeding started again prior to spawning. Thus, habitat utilisation according to spawning strategy affects the timing of fecundity down-regulation reflecting availability of resources, namely limited food resources in deep areas and higher availability in coastal areas. Offshore spawning flounder display characteristics typical for a capital spawner with ceasing of feeding and oocyte down-regulation well before spawning

  11. Fecundity regulation in relation to habitat utilisation of two sympatric flounder (Platichtys flesus) populations in the brackish water Baltic Sea

    DEFF Research Database (Denmark)

    Nissling, Anders; Thorsen, Anders; da Silva, Filipa F.G.

    2015-01-01

    Two populations of flounder (Platichtys flesus) with different life history traits inhabit the brackish water Baltic Sea. Both types share feeding areas in coastal waters during summer-autumn but utilise different habitats for spawning in spring, namely offshore spawning with pelagic eggs and...

  12. Picocyanobacteria containing a novel pigment gene cluster dominate the brackish water Baltic Sea.

    Science.gov (United States)

    Larsson, John; Celepli, Narin; Ininbergs, Karolina; Dupont, Christopher L; Yooseph, Shibu; Bergman, Bigitta; Ekman, Martin

    2014-09-01

    Photoautotrophic picocyanobacteria harvest light via phycobilisomes (PBS) consisting of the pigments phycocyanin (PC) and phycoerythrin (PE), encoded by genes in conserved gene clusters. The presence and arrangement of these gene clusters give picocyanobacteria characteristic light absorption properties and allow the colonization of specific ecological niches. To date, a full understanding of the evolution and distribution of the PBS gene cluster in picocyanobacteria has been hampered by the scarcity of genome sequences from fresh- and brackish water-adapted strains. To remediate this, we analysed genomes assembled from metagenomic samples collected along a natural salinity gradient, and over the course of a growth season, in the Baltic Sea. We found that while PBS gene clusters in picocyanobacteria sampled in marine habitats were highly similar to known references, brackish-adapted genotypes harboured a novel type not seen in previously sequenced genomes. Phylogenetic analyses showed that the novel gene cluster belonged to a clade of uncultivated picocyanobacteria that dominate the brackish Baltic Sea throughout the summer season, but are uncommon in other examined aquatic ecosystems. Further, our data suggest that the PE genes were lost in the ancestor of PC-containing coastal picocyanobacteria and that multiple horizontal gene transfer events have re-introduced PE genes into brackish-adapted strains, including the novel clade discovered here. PMID:24621524

  13. Picocyanobacteria containing a novel pigment gene cluster dominate the brackish water Baltic Sea

    Science.gov (United States)

    Larsson, John; Celepli, Narin; Ininbergs, Karolina; Dupont, Christopher L; Yooseph, Shibu; Bergman, Bigitta; Ekman, Martin

    2014-01-01

    Photoautotrophic picocyanobacteria harvest light via phycobilisomes (PBS) consisting of the pigments phycocyanin (PC) and phycoerythrin (PE), encoded by genes in conserved gene clusters. The presence and arrangement of these gene clusters give picocyanobacteria characteristic light absorption properties and allow the colonization of specific ecological niches. To date, a full understanding of the evolution and distribution of the PBS gene cluster in picocyanobacteria has been hampered by the scarcity of genome sequences from fresh- and brackish water-adapted strains. To remediate this, we analysed genomes assembled from metagenomic samples collected along a natural salinity gradient, and over the course of a growth season, in the Baltic Sea. We found that while PBS gene clusters in picocyanobacteria sampled in marine habitats were highly similar to known references, brackish-adapted genotypes harboured a novel type not seen in previously sequenced genomes. Phylogenetic analyses showed that the novel gene cluster belonged to a clade of uncultivated picocyanobacteria that dominate the brackish Baltic Sea throughout the summer season, but are uncommon in other examined aquatic ecosystems. Further, our data suggest that the PE genes were lost in the ancestor of PC-containing coastal picocyanobacteria and that multiple horizontal gene transfer events have re-introduced PE genes into brackish-adapted strains, including the novel clade discovered here. PMID:24621524

  14. Production of halomethanes and isoprene in the culture of bacteria isolated from brackish water

    Science.gov (United States)

    Fujimori, T.; Taniai, G.; Kurihara, M.; Tamegai, H.; Hashimoto, S.

    2010-12-01

    Halomethanes produced naturally are important source of halogen in troposphere and stratosphere. In the ocean, macroalgae and phytoplankton have been considered to be the main producers of halomethanes. Recent investigations have shown that marine bacteria also produces halomethane such as iodomethane. However, knowledge of aquatic halomethane production, especially by bacteria, is insufficient. Here we survey bacteria, which produce volatile organic compounds (VOCs) including halomethanes, from brackish area (salinity: about 5‰) where high halomethane productions were observed. Bacteria was isolated and incubated in marine broth 2216, which is the media for marine bacteria. The VOCs such as halomethanes in the gas phase above cultured samples was determined using dynamic headspace (GESTEL DHS) - gas chromatograph (Agilent 6890N)- mass spectrometer (Agilent 5975C). The optical density at 600 nm (OD600) was also measured during the cultured period. From the result of the isolation and measurement of VOCs, some of the isolated bacteria produced halomethanes. For example, monohalomethanes (from 1 to about 600 nM) and isoprene (up to about 400 nM) were increased for several days in the culture (dibromomethane, chloroiodomethane, bromoiodomethane, and tribromomethane were not detected). Since halomethanes are abundant at the sampling point (under 1% of light intensity of the surface), bacteria is one of the possible candidates for halomethane producer there. Now, we are studying on the identification by 16S rRNA sequence analysis of bacteria collected from brackish water.

  15. Lettuce growth and water consumption in NFT hydroponic system using brackish water

    Directory of Open Access Journals (Sweden)

    Hammady R. Soares

    2015-07-01

    Full Text Available The qualitative aspects of water, such as the preparation or replenishment of the nutrient solution, are critical to the success of hydroponic crops. Therefore, the aim of this study was to evaluate the behavior of “Americana” lettuce (cv. Tainá under increasing levels of saline stress (0.2 - control, 1.2, 2.2, 3.2, 4.2 and 5.2 dS m-1, replenishing the evapotranspiration with brackish water in Experiment I and supply water (0.2 dS m-1 in Experiment II, both used in the preparation of the nutrient solution. In both experiments, the treatments were arranged in a randomized block design, with six treatments and four replicates. Shoot fresh matter, shoot dry matter and leaf area in Experiment I suffered reductions of 15.22, 12.67 and 15.6% per unit increase of EC, respectively. In Experiment II, reductions of 8.01, 6.90 and 8.14% were observed for the same variables, respectively. In Experiments I and II, linear decrease in water consumption due to the increase in salinity was observed, with reductions of 8.83 and 5.63% for each unit increase of electrical conductivity of water when the evapotranspiration was replenished using brackish and supply water, respectively.

  16. Heterotrophic bacteria from brackish water of the southern Baltic Sea: biochemical and molecular identification and characterisation

    Directory of Open Access Journals (Sweden)

    Agnieszka Cabaj

    2006-12-01

    Full Text Available Six bacterial strains isolated from the surface water of thesouthern Baltic Sea were described on the basis of their morphological,physiological and biochemical features, and were classified onthe basis of 16S rDNA sequence analysis. Comparative analysesof the 16S rDNA sequences of five of the six bacterial strainsexamined displayed a ≥98% similarity to the sequences availablein the NCBI GenBank. The 16S rDNA sequence of strain 2 sharedonly a 96% similarity with other published sequences, whichsuggests that this is a new, hitherto unknown species. The isolatedheterotrophic bacteria belong to the families Bacillaceae(strain 1, Flexibacteriaceae (strain 2, Sphingomonadaceae(strains 3, 5, Micrococcaceae (strain 4 and Aurantimonadaceae(strain 6.    This is the first study in which the polyphasic approach hasbeen applied to the identification of heterotrophic bacteriafrom the brackish waters of the Gulf of Gdańsk and Gdańsk Deep.

  17. Activated packed bed bioreactor for rapid nitrification in brackish water hatchery systems.

    Science.gov (United States)

    Kumar, V J Rejish; Achuthan, Cini; Manju, N J; Philip, Rosamma; Singh, I S Bright

    2009-03-01

    A packed bed bioreactor (PBBR) was developed for rapid establishment of nitrification in brackish water hatchery systems in the tropics. The reactors were activated by immobilizing ammonia-oxidizing (AMONPCU-1) and nitrite-oxidizing (NIONPCU-1) bacterial consortia on polystyrene and low-density polyethylene beads, respectively. Fluorescence in situ hybridization demonstrated the presence of autotrophic nitrifiers belong to Nitrosococcus mobilis, lineage of beta ammonia oxidizers and nitrite oxidizer Nitrobacter sp. in the consortia. The activated reactors upon integration to the hatchery system resulted in significant ammonia removal (P systems. With spent water the reactors could establish nitrification with high percentage removal of ammonia (78%), nitrite (79%) and BOD (56%) within 7 days of initiation of the process. PBBR is configured in such a way to minimize the energy requirements for continuous operation by limiting the energy inputs to a single stage pumping of water and aeration to the aeration cells. The PBBR shall enable hatchery systems to operate under closed recirculating mode and pave the way for better water management in the aquaculture industry. PMID:19039611

  18. Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in Na-Cl brackish waters of north-western Sardinia, Italy

    Directory of Open Access Journals (Sweden)

    G. Mongelli

    2013-01-01

    Line supporting the idea that they are meteoric in origin. A relevant consequence of the meteoric origin of the Nurra Na-Cl type water is that the Br/Cl ratio, extensively used to assess the origin of salinity in fresh water, should be used with care also in near coastal carbonate aquifers. Overall, and consistent with the geology and the lithological features of the study area, δ34S and δ18O in dissolved sulphate suggest that water-rock interaction is the responsible for the Nurra Na-Cl brackish water composition. Evaporites dissolution also explain the high chlorine contents since halite has been detected in the gypsum levels. Finally, the Nurra Na-Cl brackish water are undersaturated with respect to the more soluble salts involving, in a climate evolving toward semi-arid conditions, that the salinization process could dramatically intensify in the near future.

  19. Estratégias de uso de água salobra na produção de alface em hidroponia NFT Strategies for use of brackish water in NFT hydroponic lettuce production

    Directory of Open Access Journals (Sweden)

    Márcio S. Alves

    2011-05-01

    Full Text Available Plantas de alface crespa 'Verônica' foram cultivadas em condições hidropônicas, objetivando avaliar três diferentes estratégias de emprego de águas salobras: 1 águas salobras para reposição das perdas por evapotranspiração (ETc e água doce para o preparo da solução nutritiva (SN; 2 águas salobras para o preparo da SN e água doce para reposição da ETc; 3 águas salobras para o preparo da SN e reposição da ETc. Os níveis de salinidade da água foram obtidos pela adição de NaCl à água doce (0,27 dS m-1: 1,45; 2,51; 3,6; 5,41 e 7,5 dS m-1. O experimento foi conduzido em quatro blocos aleatorizados, com quatro repetições por tratamento. Uma estrutura de pesquisa foi construída com 72 parcelas que simulam a técnica do fluxo laminar de nutrientes (NFT. O uso de água salobra apenas para repor a ETc não produziu efeito sobre a produção da alface. Por outro lado, o uso de águas salobras para o preparo da SN e água doce para reposição da ETc, reduziu o rendimento da alface (massa de matéria fresca da parte aérea em 4,99% por (dS m-1. O rendimento foi reduzido em 7% por dS m-1 quando águas salobras foram usadas tanto para o preparo da SN quanto para reposição da ETc. Apesar da redução linear da produção da alface com o aumento da salinidade da água, sintomas depreciativos para a qualidade da alface hidropônica não foram registrados.Plants of crisphead lettuce cv. 'Verônica' were grown under hydroponic conditions aiming to evaluate three different strategies of brackish waters utilization: 1 brackish waters to replace the evapotranspiration loss (ETc and fresh water to prepare nutrient solution (NS; 2 brackish waters to prepare NS and fresh water to replace the ETc; 3 brackish waters to prepare NS and replace ETc. The levels of water salinity were obtained by addition of NaCl to fresh water (0.27 dS m-1: 1.45; 2.51; 3.6; 5.41 and 7.5 dS m-1. The experiment was conducted in randomized blocks with four

  20. High pressure membrane foulants of seawater, brackish water and river water: origin assessed by sugar and bacteriohopanepolyol signatures.

    Science.gov (United States)

    Mondamert, L; Labanowski, J; N'Goye, F; Talbot, H M; Croue, J P

    2011-01-01

    The present work aimed to study the origin of foulant material recovered on membranes used in water treatment. Firstly, sugar signatures were assessed from the monosaccharide composition. As results were not conclusive, a statistical approach using discriminant analysis was applied to the sugar data set in order to predict the origin of the foulant material. Three groups of various origins (algal, microbial, continental dissolved organic matter) were used as sugar references for the prediction. The results of the computation showed that the origin of reverse osmosis (RO) seawater foulant material is influenced by both the location of the water sources and the season. RO brackish water and nanofiltration river water foulant materials had a terrestrial origin. Secondly, bacteriohopanepolyol signatures indicated that RO seawater foulant material had a marine signature, RO brackish water foulant material had both a marine and a terrestrial origin and the nanofiltration river water foulant material contained only a terrestrial signature. PMID:21104476

  1. High pressure membrane foulants of seawater, brackish water and river water: Origin assessed by sugar and bacteriohopanepolyol signatures

    KAUST Repository

    Mondamert, Leslie

    2011-01-01

    The present work aimed to study the origin of foulant material recovered on membranes used in water treatment. Firstly, sugar signatures were assessed from the monosaccharide composition. As results were not conclusive, a statistical approach using discriminant analysis was applied to the sugar data set in order to predict the origin of the foulant material. Three groups of various origins (algal, microbial, continental dissolved organic matter) were used as sugar references for the prediction. The results of the computation showed that the origin of reverse osmosis (RO) seawater foulant material is influenced by both the location of the water sources and the season. RO brackish water and nanofiltration river water foulant materials had a terrestrial origin. Secondly, bacteriohopanepolyol signatures indicated that RO seawater foulant material had a marine signature, RO brackish water foulant material had both a marine and a terrestrial origin and the nanofiltration river water foulant material contained only a terrestrial signature. © 2011 Taylor & Francis.

  2. Differences in osmotolerance in freshwater and brackish water populations of Theodoxus fluviatilis (Gastropoda: Neritidae) are associated with differential protein expression

    OpenAIRE

    Symanowski, Frauke; Hildebrandt, J.-P.

    2010-01-01

    The euryhaline gastropod Theodoxus fluviatilis is found in northern Germany in freshwater or in brackish water habitats in the Baltic Sea. Previous studies have revealed that individuals from both habitats are not distinguishable by morphological characters or by sequence comparison of DNA encoding 16S RNA or cytochrome C. As reported in this study, animals collected in the two habitats differ substantially in their physiological ability to adapt to different salinities. Comparison of accumul...

  3. Stability of a carbon gel electrode when used for the electro-assisted removal of ions from brackish water

    OpenAIRE

    Haro Remón, Marta; Rasines, Gloria; Macías, C.; Ovín Ania, María Concepción

    2011-01-01

    [EN] A porous carbon gel obtained from the poly-condensation of resorcinol and formaldehyde was synthesized and used as an electrode material for the capacitive deionization (CDI) of synthetic brackish water. The desalting capacity of this material was evaluated in terms of applied voltage and zero-voltage regeneration over a number of cycles, and compared to that of commercially available carbon materials (powdered activated carbon and activated carbon cloth). Due to an adequate combination ...

  4. Investigation of changes in the microflora of brackish water passing through power plant cooling systems

    International Nuclear Information System (INIS)

    Changes in the bacterial- and phytoplankton population in the brackish water during the passage of fresh water cooling systems in the community power plant of Kiel (GKK) and in the nuclear power plant of Brunsbuettel were subject of the examinations. In addition, laboratory tests were carried out and a method was developed to determine thermal changes in the bacterial activity (measured as glucose uptake) in the condensator independent on the mechanical influences. Following points describe the starting position in the incoming cooling water of the GKK: 1) The annual cycle of the bacterial activity is temporally delayed in relation to the natural course of the temperature. 2) The annual course of the phytoplankton is primarily regulated by the light and nutrition offered while the temperature is only of indirect importance. 3) The particular organic material is, beside the dissolved organic compounds, important for the biological oxygen household in the Kieler Foerde. Changes in the bacterial population and the phytoplankton flora occur during the passage of the cooling system in the community power plant of Kiel. In the heated water samples behind the condensator, an increase in the bacterial activity by 11% on an average is seen. This increase is also found in the biochemical oxygen consumption after 30 hours. On an average, it is about 19%. Changes in the phytoplankton in the cooling water are only insignificantly due to the thermal influences; here, the hazards are rather due to the mechanical burden. At the KBB, an annual cycle could not be recorded because of the numerous operational disturbances. The bacterial glucose uptake in the river Elbe shows no temperature-dependent fluctuations. (orig./MG)

  5. Effects of snow condition on microbial respiration of Scots pine needle litter in a boreal forest

    Science.gov (United States)

    Ohnuki, Masataka; Domisch, Timo; Dannoura, Masako; Ataka, Mioko; Finér, Leena; Repo, Tapani; Osawa, Akira

    2016-04-01

    Climate warming scenarios predict decreasing snow depths and increasing winter precipitation in boreal forests ("rain on snow"). I These conditions may affect the decomposition and the microbial respiration of leaf litter, contributing a major part of tree litters, To understand how different snow conditions during winter would affect the microbial respiration of Scots pine needle litter in a boreal forest, we conducted a laboratory experiment using needle litter of two age classes (newly dropped and older litter). The experiment simulated four different winter treatments, followed by spring and early summer : (1) ambient snow cover (SNOW), (2) Compressed snow and ice encasement (ICE), (3) frozen flood (FLOOD) and (4) no snow cover at all (NO SNOW). The experiment was carried out in four walk-in dasotrons (n=3) with soil temperatures of -2° C and air temperatures of 2° C during winter and increased to 15° C and 20° C during spring, respectively . Needle litter samples were collected three times (prior to the winter, just after winter and at the end of the experiment). We evaluated the microbial respiration from the litter at several temperatures (-5° C, 0° C, 5° C and 12° C), the SIR index (an index estimating the microbial biomass), and the C/N ratio .And we calculated Q10 value (index of microbial respiration activity) using microbial respiration data. We found significant differences in microbial respiration between the newly dropped and older litter at the beginning and at the end of the experiment. However, there were no significant differences in Q10 value and the SIR (index of microbial biomass) between the different winter treatments. All samples showed decrease of microbial activity with time. Finally, we conclude that the winter snow conditions with mild air temperatures as used in our experiment, are not detrimentally affecting the Scots pine needle litter decomposition and its respiration.

  6. Assessment of the fresh-and brackish-water resources underlying Dunedin and adjacent areas on northern Pinellas County, Florida

    Science.gov (United States)

    Knochenmus, L.A.; Swenson, E.S.

    1996-01-01

    The city of Dunedin is enhancing their potable ground-water resources through desalination of brackish ground water. An assessment of the fresh- and brackish-water resources in the Upper Floridan aquifer was needed to estimate the changes that may result from brackish-water development. The complex hydrogeologic framework underlying Dunedin and adjacent areas of northern Pinellas County is conceptualized as a multilayered sequence of permeable zones and confining and semiconfining units. The permeable zones contain vertically spaced, discrete, water-producing zones with differing water quality. Water levels, water-level responses, and water quality are highly variable among the different permeable zones. The Upper Floridan aquifer is best characterized as a local flow system in most of northern Pinellas County. Pumping from the Dunedin well field is probably not influencing water levels in the aquifer outside Dunedin, but has resulted in localized depressions in the potentiometric surface surrounding production-well clusters. The complex geologic layering combined with the effects of production-well distribution probably contribute to the spatial and temporal variability in chloride concentrations in the Dunedin well field. Chloride concentrations in ground water underlying the Dunedin well field vary both vertically and laterally. In general, water-quality rapidly changes below depths of 400 feet below sea level. Additionally, randomly distributed water-producing zones with higher chloride concentrations may occur at shallow, discrete intervals above 400 feet. A relation between chloride concentration and distance from St. Joseph Sound is not apparent; however, a possible relation exists between chloride concentration and production-well density. Chloride-concentration data from production wells show a consistently increasing pattern that has accelerated since the late 1980's. Chloride-concentration data from 15 observation wells show increasing trends for 6 wells

  7. Hierarchical Ordered Mesoporous Carbon from Phloroglucinol-Glyoxal and its Application in Capacitive Deionization of Brackish Water

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Sheng [ORNL; DePaoli, David W [ORNL; Kiggans, Jim [ORNL; Mayes, Richard T [ORNL; Tsouris, Costas [ORNL; Mahurin, Shannon Mark [ORNL

    2010-01-01

    Templated carbon materials have recently received tremendous attention due to energy storage and separations applications. Hierarchical structures are ideal for increased mass-transport throughout the carbon material. A new ordered mesoporous carbon material has been developed using glyoxal which exhibits a hierarchical structure with pore sizes up to 200 nm. The hierarchical structure arises from the cross linking reagent and not from the standard spinodal decomposition of a secondary solvent. The carbon material was studied for potential application as a capacitive deionization (CDI) electrode for brackish water. Results indicate that the hierarchical structure provides a pathway for faster adsorption kinetics when compared to standard resorcinol-formaldehyde CDI electrodes.

  8. Attenuation of rare earth elements in a boreal estuary

    Science.gov (United States)

    Åström, Mats E.; Österholm, Peter; Gustafsson, Jon Petter; Nystrand, Miriam; Peltola, Pasi; Nordmyr, Linda; Boman, Anton

    2012-11-01

    This study focuses on attenuation of rare earth elements (REE) when a boreal creek, acidified and loaded with REE and other metals as a result of wetland drainage, empties into a brackish-water estuary (salinity extract metals from the settling material. Aluminium, Fe and REE transported by the acidic creek were extensively removed in the inner/central estuary where the acidic water was neutralised, whereas Mn was relatively persistent in solution and thus redistributed to particles and deposited further down the estuary. The REE removal was caused by several contemporary mechanisms: co-precipitation with oxyhydroxides (mainly Al but also Fe), complexation with flocculating humic substances and sorption to suspended particles. Down estuary the dissolved REE pool, remaining after removal, was fractionated: the Humic Model after revision and updating, predicted that the dissolved (humic substances. Acid sulphate soils, the source of the REE and other metals in the creek water, are widespread on coastal plains worldwide and therefore the REE attenuation patterns and mechanisms identified in the studied estuary are relevant for recognition of similar geochemical processes and conditions in a variety of coastal locations.

  9. Biogas production from high-yielding energy crops in boreal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Seppala, M.

    2013-11-01

    In this thesis, the methane production potential of traditional and novel energy crops was evaluated in boreal conditions. The highest methane yield per hectare was achieved with maize (4 000-9 200 m{sup 3}CH{sub 4} ha{sup -1} a{sup -1}) and the second highest with brown knapweed (2 700-6 100 m{sup 3}CH{sub 4} ha{sup -1} a{sup -1}). Recently, the most feasible energy crop, grass, produced 1 200-3 600 m{sup 3}CH{sub 4} ha{sup -1} a{sup -1}. The specific methane yields of traditional and novel energy crops varied from 170-500 l kg{sup -1} volatile solid (VS). The highest specific methane yields were obtained with maize, while the novel energy crops were at a lower range. The specific methane yields decreased in the later harvest time with maize and brown knapweed, and the specific methane yield of the grasses decreased from the 1st to 2nd harvests. Maize and brown knapweed produced the highest total solid (TS) yields per hectare 13-23 tTS ha{sup -1}, which were high when compared with the TS yields of grasses (6-13 tTS ha{sup -1}). The feasibility of maize and brown knapweed in co-digestion with liquid cow manure, in continuously stirred tank reactors (CSTR), was evaluated. According to the CSTR runs, maize and brown knapweed are suitable feeds and have stable processes, producing the highest methane yields (organic loading rate 2 kgVS m{sup -3}d{sup -1}), with maize at 259 l kgVS{sup -1} and brown knapweed at 254 l kgVS{sup -1}. The energy balance (input/output) of the cultivation of the grasses, maize and brown knapweed was calculated in boreal conditions, and it was better when the digestate was used as a fertilizer (1.8-4.8 %) than using chemical fertilizers (3.7-16.2 %), whose production is the most energy demanding process in cultivation. In conclusion, the methane production of maize, grasses and novel energy crops can produce high methane yields and are suitable feeds for anaerobic digestion. The cultivation managements of maize and novel energy crops for

  10. Ontogenetic changes in location and morphology of chloride cells during early life stages of the Nile tilapia Oreochromis niloticus adapted to fresh and brackish water.

    Science.gov (United States)

    Fridman, S; Bron, J E; Rana, K J

    2011-09-01

    Ontogenetic changes in the location, size, density and morphology of chloride cells in the Nile tilapia Oreochromis niloticus adapted to fresh and brackish water are described using Na(+) /K(+) -ATPase immunohistochemistry, light microscopy (LM), scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). The pattern of chloride cell distribution changed during development under both treatments, with chloride cell density decreasing significantly from hatch to 7 days post-hatch, but appearing on the inner opercular area at 3 days post-hatch and increasing significantly thereafter (P larvae. In both treatments, chloride cells located on the outer operculum and tail showed a marked increase in size with age, but cells located on the abdominal epithelium of the yolk sac and the inner operculum showed a significant decrease in size (P larvae from 1 day post-hatch onwards were always significantly larger (P larvae. SEM revealed structural differences in chloride cell apical morphology according to environmental conditions. There appears to be clearly defined temporal staging of the appearance of adaptive mechanisms that confer an ability to cope with varying environmental conditions during early development. PMID:21884103

  11. Boreal forests

    International Nuclear Information System (INIS)

    We review patterns and processes important for biodiversity in the Fennoscandian boreal forest, describe man's past and present impact and outline a strategy for conservation. Natural disturbances, particularly forest fire and gap formation, create much of the structural and functional diversity in forest ecosystems. Several boreal plants and animals are adapted to fire regimes. In contrast, many organisms (epiphytic lichens, fungi, invertebrates) require stable conditions with long continuity in canopy cover. The highly mechanized and efficient Fennoscandian forest industry has developed during the last century. The result is that most natural forest has been lost and that several hundreds of species, mainly cryptograms and invertebrates, are threatened. The forestry is now in a transition from exploitation to sustainable production and has recently incorporated some measures to protect the environment. Programmes for maintaining biodiversity in the boreal forest should include at least three parts. First, the system of forest reserves must be significantly improved through protection of large representative ecosystems and key biotopes that host threatened species. Second, we must restore ecosystem properties that have been lost or altered. Natural disturbance regimes must be allowed to operate or be imitated, for example by artificial fire management. Stand-level management should particularly increase the amount of coarse woody debris, the number of old deciduous trees and large, old conifers, by using partial cutting. Third, natural variation should also be mimicked at the landscape level, for example, by reducing fragmentation and increasing links between landscape elements. Long-term experiments are required to evaluate the success of different management methods in maintaining biodiversity in the boreal forest. (au) 260 refs

  12. Autonomous system without batteries for brackish water desalination; Sistema autonomo sem baterias para dessalinizacao de agua salobra

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Eduardo Henrique Pereira de; Bezerra, Luiz Daniel Santos; Antunes, Fernando Luiz Marcelo [Universidade Federal do Ceara (PPGEE/UFC), Fortaleza, CE (Brazil). Programa de Pos -Graduacao em Engenharia Eletrica

    2008-07-01

    Ones of the goods most precious of the humanity, in the current times, with certainty is the drinking waters. Each scarcer and basic time for survival. In everybody more than 6,000 children die every day victims of some type of illness provoked for contaminated water (WHO, 2003). The underground water for being free of contamination is a good alternative, however its exploration if it becomes each more expensive time, since the water of better quality, is located in deeper sheets. In the state of the Ceara, techniques to explore water of deep well are each more frequent time, however, present a great inconvenience, most of the excavated wells, present brackish water, improper for the human consumption. In the attempt to make possible these wells the water is treated by desalination process. This article presents the practical implementation of a desalination the reverse Osmosis, Pump high-pressure supplied by solar photovoltaic energy system. (author)

  13. Assessment of wind energy to power solar brackish water greenhouse desalination units. A case study from Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoudi, Hacene [Laboratory of Water and Environment, Hassiba Ben Bouali University, Chlef, P.O. Box 151 (Algeria); Faculty of Sciences and Engineering Sciences, Hassiba Ben Bouali University, Chlef (Algeria); Spahis, Nawel [Faculty of Sciences and Engineering Sciences, Hassiba Ben Bouali University, Chlef (Algeria); Goosen, Mattheus F. [Alfaisal University, P.O. Box 50927, Riyadh 11533, KSA (Saudi Arabia); Sablani, Shyam [Biological Systems Engineering, Washington State University, Pullman, WA (United States); Abdul-wahab, Sabah A. [College of Engineering, P.O. Box 33, Sultan Qaboos University, Al-Khod 123, Muscat (Oman); Ghaffour, Noreddine [Middle East Desalination Research Center, P.O. Box 21, P.C. 133, Muscat (Oman); Drouiche, Nadjib [Silicon Technology Development Unit (UDTS), 2 Bd Frantz Fanon BP399 Algiers (Algeria)

    2009-10-15

    The Algerian desert dominates large parts of the country's vast territory, and Algeria is among the countries filling most of the world's largest desert. In fact the country is over 80% desert. Even though more than 80% of the population is located in the northern Mediterranean coastal zone, most of oil and gas fields are located in the country's vast southern desert called Sahara. Furthermore, the desert region is developed into a major tourist destination. This arid zone region is characterized by a lack of potable water. However, in addition to the abundant solar energy, the region is also endowed with important wind and brackish groundwater resources with different qualities. Therefore, a brackish water greenhouse desalination unit that is powered by wind energy is a good solution for desalting groundwater for irrigation purposes in this region. Brackish water can be used to cool the greenhouse, creating the proper climate to grow valuable crops. Moreover, at the same time the fresh water that is produced in this system may be sufficient for the irrigation of crops grown inside the unit. In this study, five typical regions in the Sahara were selected and investigated. These regions were selected since they were areas of traditional agriculture. The frequency distributions of wind speed data were collected from Surface Meteorology and Solar Energy (SSE) statistics developed by NASA and evaluated for a 10-year period. The distributions were used to determine the average wind speed and the available wind power for the five locations. The results indicated that the available wind energy is a suitable resource for power production and can be used to provide the required electricity for the brackish groundwater greenhouse desalination units. (author)

  14. The soil-water flow system beneath a cotton field in arid north-west China, serviced by mulched drip irrigation using brackish water

    Science.gov (United States)

    Li, Xianwen; Jin, Menggui; Huang, Jinou; Yuan, Jingjing

    2015-02-01

    A field experiment was carried out in southern Xinjiang, China, to reveal soil-water flow pattern beneath a combined plastic-mulch (film) and drip-irrigation system using brackish water. The soil-water flow system (SWFS) was characterized from soil surface to the water table based on observed spatio-temporal distribution of total soil-water potential, water content and electric conductivity. Root suction provided a strong inner sink. The results indicated that SWFS determined the soil salinity and moisture distribution. Drip-irrigation events could leach excess salts from the root zone and provide soil conditions with a tolerable salinity level that supports the growth of cotton. High-salinity strips were formed along the wetting front and at the bare soil surface. Hydrogeology conditions, irrigation regime, climate, plant growth and use of mulch would affect potential sources and sinks, boundary conditions and the size of the SWFS. At depth 0-60 cm, the soil salinity at the end of the irrigation season was 1.9 times that at the beginning. Beneath the mulch cover, the soil-water content in the `wide rows' zone (55 cm between the two rows with no drip line) was higher than that in the `narrow rows' zone (15 cm between the two rows with a drip line) due to the strong root-water uptake. The downward water flow below the divergent curved surface of zero flux before irrigation, and the water-table fluctuation with irrigation events, indicated that excessive irrigation occurred.

  15. Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in the Na-Cl brackish waters of northwestern Sardinia, Italy

    Directory of Open Access Journals (Sweden)

    G. Mongelli

    2013-07-01

    conclusion that they are meteoric in origin. A significant consequence of the meteoric origin of the Na-Cl-type water studied here is that the Br / Cl ratio, extensively used to assess the origin of salinity in fresh water, should be used with care in carbonate aquifers that are near the coast. Overall, δ34S and δ18O levels in dissolved SO4 suggest that water–rock interaction is responsible for the Na-Cl brackish composition of the water hosted by the Jurassic and Triassic aquifers of the Nurra, and this is consistent with the geology and lithological features of the study area. Evaporite dissolution may also explain the high Cl content, as halite was detected within the gypsum deposits. Finally, these Na-Cl brackish waters are undersaturated with respect to the more soluble salts, implying that in a climate evolving toward semi-arid conditions, the salinization process could intensify dramatically in the near future.

  16. Early diagenetic high-magnesium calcite and dolomite indicate that coal balls formed in marine or brackish water: Stratigraphic and paleoclimatic implications

    Science.gov (United States)

    Raymond, Anne

    2016-04-01

    Coal balls are carbonate and pyrite permineralizations of peat that contain three-dimensional plant fossils preserved at the cellular level. Coal balls, which occur in Pennsylvanian and earliest Permian equatorial coals, provide a detailed record of terrestrial ecology and tropical climate during the Late Paleozoic Ice Age; yet their depositional environment remains controversial. The exquisite preservation of some coal-ball fossils, e.g. pollen with pollen tubes and leaves with mesophyll, indicates rapid formation. The presence of abundant, cement-filled, void spaces within and between the plant debris in most coal balls indicates that they formed in uncompacted peat, near the surface of the mire. Botanical, taphonomic and isotopic evidence point to a freshwater origin for coal balls. The nearest living relatives of coal ball plants (modern lycopsids, sphenopsids, marratialean ferns and conifers) grow in fresh water. Coal-ball peat contains a high percentage of aerial debris, similar to modern freshwater peat. The stable oxygen isotopes of coal-ball carbonate (δ18O = 16 to 3 per mil) suggest a freshwater origin. However, the widespread occurrence of marine invertebrates and early diagenetic framboidal pyrite in coal balls suggests that many formed in close proximity to marine water. Indeed, carbonate petrology points to a marine or brackish water origin for the first-formed carbonate cements in coal balls. Petrographic and geochemical (microprobe) analysis of coal-ball carbonates in Pennsylvanian coals from the midcontinent of North America (Western Interior Basin, West Pangaea) and the Ruhr and Donets Basins (East Pangaea) indicate that the first formed carbonate is either radaxial, nonstochiometric dolomite or high magnesium calcite (9 - 17 mol % MgCO3, indicating precipitation in marine or brackish water. Although both primary dolomite and high magnesium calcite can form in lacustrine settings, the lakes in which these minerals form occur in carbonate terranes

  17. Depth-dependent molecular composition and photoreactivity of dissolved organic matter in a Boreal Lake under winter and summer conditions

    Directory of Open Access Journals (Sweden)

    M. Gonsior

    2013-05-01

    Full Text Available Transformations of dissolved organic matter (DOM in boreal lakes lead to large greenhouse gas emissions as well as substantial carbon storage in sediments. Using novel molecular characterization approaches and photochemical degradation experiments we studied how seasonal patterns in water column stratification affected the DOM in a Swedish lake under late winter and early summer conditions. Dissolved organic carbon (DOC concentrations were consistently higher above the sediment when compared to surface waters. Solely photobleaching could not explain this difference in DOC because the lake was covered by 40 cm thick ice during late winter sampling and still showed the same DOC trend. The differences in the molecular diversity between surface water DOM in winter and summer were consistent with summertime photobleaching/decarboxylation reactions and a possible bacterial consumption of photo-products. Additional photodegradation experiments using simulated sunlight showed a production of highly oxidized organic molecules and low molecular weight compounds in all late winter samples and also in the deep water sample in summer. In the surface summer DOM sample, few such molecules were produced during the photodegradation experiments confirming that DOM was already photobleached prior to the experiments. This study suggests that photobleaching, and therefore also the ice cover during winter plays a central role in surface DOM structural dynamics with important differences in the molecular composition of DOM between surface and deep boreal lake waters. The release of DOC from boreal lake sediments likely also contribute to this pattern. Photochemical degradation of DOM may be more extensive following ice-out and water column turnover when non-light exposed and thereby photosensitive DOM is photo-mineralized. Hence, the yearly DOM photo-mineralization may be greater than inferred from studies of recently light exposed DOM.

  18. Hepatic pathologies in the brackish water catfish (Chrysichthys nigrodigitatus) from contaminated locations of the Lagos lagoon complex

    Science.gov (United States)

    Olarinmoye, O.; Taiwo, V.; Clarke, E.; Kumolu-Johnson, C.; Aderinola, O.; Adekunbi, F.

    2010-01-01

    Several toxicological studies into the effects of aquatic pollutants on the liver of teleost fish exist in literature. The focus on the liver in these studies is predicated on its central nature in the scheme of biotransformation and excretion of xenobiotics following exposure in polluted water bodies. As a consequence of the latter primary role of the liver in these processes it is regarded as a predilective site for the sub lethal effects of xenobiotics on the organism usually detectable at histological level. Hepatic histopathology recorded in livers from feral populations of the brackish water catfish Chrysichthys nigrodigitatus from locations on the Lagos lagoon complex with significant anthropogenic inputs from denizen populations and industries are presented. Liver sections from sixty specimens from two locations on the Lagos lagoon complex (Badagry lagoon: 6??24'N, 2??56'E; and Lagos lagoon: 6??29'N, 3??22'E) were analysed. Observed pathologies included hydropic degeneration (58%), portal / sinusoidal congestion (33%), hepatic necrosis (26%), hemosiderosis (12%) and foci of cellular alterations (FCA's). No obvious oncologic features were observed; the presence of the hydropic Vacuolation lesion was taken as prelude to the development of neoplasms and discussed as such. ?? 2009, Penkala Bt., Budapest, Hungary.

  19. Rehabilitation of Seven (7) Hydrocarbon Contaminated Sites in a Brackish Water/Lagoon Environment in South Trinidad

    Science.gov (United States)

    Mohammed, Avryl; Ramnath, Kelvin; Dyal, Shyam; Lalla, Francesca; Roopchand, Jaipersad

    2007-12-01

    The Petroleum Company of Trinidad and Tobago Limited operates in a wide diversity of tropical habitats in South Trinidad one of which is a brackish water environment known as the Godineau Swamp. Historically this field was operated by predecessor multinational companies, who at that time employed operational practices based on the absence of legal requirements, that were not environmentally considerate. Following a detailed environmental audit of the field (also known as the Oropouche Field), seven (7) contaminated sites were found, that presented a risk to the lagoon and its associated mangrove swamp ecology. Remediation of the seven (7) sites was done in two (2) phases; phase 1 being sampling and characterization of the waste inclusive of migration and phase 2 the actual on-site soil remediation. Phase 1 conducted during the period December 2004 to February 2005, indicated a total of 19,484 m3 of contaminated material with TPH being the main contaminant. The average concentration of TPH was 3.25%. Phase 2 remediation was initiated in October 2005 and involved the following three (3) aspects to achieve a TPH concentration of less than 1%: ▪ Preparation of waste remediation sites adjacent to contaminated sites and excavation and spreading onto cells ▪ Bioremediation onsite using naturally occurring bacteria and rototilling ▪ Rehabilitation and closure of the site following accepted lab results. The benefits of conducting this project in the petroleum industry are to ensure compliance to the national Sensitive Areas Rules and Draft Waste Management Rules, conformance to ISO 14001 Certification requirements and conservation of biodiversity in the mangrove swamp.

  20. Meteorological pre-processing of incoming solar radiation and heat flux over a sparse boreal forest at a northern site during winter conditions

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Batchvarova, E.

    Measurements from Northern Finland on radiation and turbulent fluxes over a sparse boreal forest with snow-covered ground were analysed. The measurements represent harsh winter conditions characterized by low sun angles. The absorption of incoming solar radiation in clear skies (turbidity) was fo...

  1. Realized niche width of a brackish water submerged aquatic vegetation under current environmental conditions and projected influences of climate change.

    Science.gov (United States)

    Kotta, Jonne; Möller, Tiia; Orav-Kotta, Helen; Pärnoja, Merli

    2014-12-01

    Little is known about how organisms might respond to multiple climate stressors and this lack of knowledge limits our ability to manage coastal ecosystems under contemporary climate change. Ecological models provide managers and decision makers with greater certainty that the systems affected by their decisions are accurately represented. In this study Boosted Regression Trees modelling was used to relate the cover of submerged aquatic vegetation to the abiotic environment in the brackish Baltic Sea. The analyses showed that the majority of the studied submerged aquatic species are most sensitive to changes in water temperature, current velocity and winter ice scour. Surprisingly, water salinity, turbidity and eutrophication have little impact on the distributional pattern of the studied biota. Both small and large scale environmental variability contributes to the variability of submerged aquatic vegetation. When modelling species distribution under the projected influences of climate change, all of the studied submerged aquatic species appear to be very resilient to a broad range of environmental perturbation and biomass gains are expected when seawater temperature increases. This is mainly because vegetation develops faster in spring and has a longer growing season under the projected climate change scenario. PMID:24933438

  2. Branchial Na+:K+:2Cl- cotransporter 1 and Na+/K+-ATPase α-subunit in a brackish water-type ionocyte of the euryhaline freshwater white-rimmed stingray, Himantura signifer

    Directory of Open Access Journals (Sweden)

    Yuen K Ip

    2013-12-01

    Full Text Available Himantura signifer is a freshwater stingray which inhabits rivers in Southeast Asia. It can survive in brackish water but not seawater. In brackish water, it becomes partially ureosmotic, but how it maintains its plasma hypoionic to the external medium is enigmatic because of the lack of a rectal gland. Here, we report for the first time the expression of Na+:K+:2Cl− cotransporter 1 (nkcc1 in the gills of freshwater H. signifer, and its moderate up-regulation (~2-fold in response to brackish water (salinity 20 acclimation. The absence of the Ste20-related proline-alanine-rich kinase and oxidation stress response kinase 1 interaction site from the N-terminus of H. signifer Nkcc1 suggested that it might not be effectively activated by stress kinases in response to salinity changes as in more euryhaline teleosts. The increased activity of Nkcc1 during salt excretion in brackish water would lead to an influx of Na+ into ionocytes, and the maintenance of intracellular Na+ homeostasis would need the cooperation of Na+/K+-ATPase (Nka. We demonstrated for the first time the expression of nkaα1, nkaα2 and nkaα3 in the gills of H. signifer, and the up-regulation of the mRNA expression of nkaα3 and the overall protein abundance of Nkaα in response to acclimation to brackish water. Immunofluorescence microscopy revealed the presence of a sub-type of ionocyte, co-expressing Nkcc1 and Nkaα, near the base of the secondary lamellae in the gills of H. signifer acclimated to brackish water, but this type of ionocyte was absent from the gills of fish kept in fresh water. Hence, there could be a change in the function of the gills of H. signifer from salt absorption to salt excretion during brackish water acclimation in the absence of a functioning rectal gland.

  3. Branchial Na(+):K(+):2Cl(-) cotransporter 1 and Na(+)/K(+)-ATPase α-subunit in a brackish water-type ionocyte of the euryhaline freshwater white-rimmed stingray, Himantura signifer.

    Science.gov (United States)

    Ip, Yuen K; Hiong, Kum C; Wong, Samuel Z H; Ching, Biyun; Chen, Xiu L; Soh, Melody M L; Chng, You R; Ong, Jasmine L Y; Wilson, Jonathan M; Chew, Shit F

    2013-01-01

    Himantura signifer is a freshwater stingray which inhabits rivers in Southeast Asia. It can survive in brackish water but not seawater. In brackish water, it becomes partially ureosmotic, but how it maintains its plasma hypoionic to the external medium is enigmatic because of the lack of a rectal gland. Here, we report for the first time the expression of Na(+):K(+):2Cl(-) cotransporter 1 (nkcc1) in the gills of freshwaterH. signifer, and its moderate up-regulation (~2-fold) in response to brackish water (salinity 20) acclimation. The absence of the Ste20-related proline-alanine-rich kinase and oxidation stress response kinase 1 interaction site from the N-terminus of H. signifer Nkcc1 suggested that it might not be effectively activated by stress kinases in response to salinity changes as in more euryhaline teleosts. The increased activity of Nkcc1 during salt excretion in brackish water would lead to an influx of Na(+) into ionocytes, and the maintenance of intracellular Na(+) homeostasis would need the cooperation of Na(+)/K(+)-ATPase (Nka). We demonstrated for the first time the expression of nkaα1, nkaα2 and nkaα3 in the gills of H. signifer, and the up-regulation of the mRNA expression of nkaα3 and the overall protein abundance of Nkaα in response to acclimation to brackish water. Immunofluorescence microscopy revealed the presence of a sub-type of ionocyte, co-expressing Nkcc1 and Nkaα, near the base of the secondary lamellae in the gills of H. signifer acclimated to brackish water, but this type of ionocyte was absent from the gills of fish kept in fresh water. Hence, there could be a change in the function of the gills of H. signifer from salt absorption to salt excretion during brackish water acclimation in the absence of a functioning rectal gland. PMID:24339817

  4. First European record of the invasive brackish water clam Rangia cuneata (G.B. Sowerby I, 1831) (Mollusca: Bivalvia)

    OpenAIRE

    Verween, A; Kerckhof, F; Vincx, M.; Degraer, S.

    2006-01-01

    A population of Rangia cuneata (G.B. Sowerby I, 1831), an estuarine bivalve, has been recorded in the harbour of Antwerp, Belgium. This species is new to the European brackish water fauna. After initially finding only a few small individuals in August 2005, R. cuneata was encountered frequently in the pipes of the cooling water system of an industrial plant from February 2006 onwards. Before this present record, R. cuneata was only known from the Gulf of Mexico and the Atlantic coast of North...

  5. 基质栽培对微咸水灌溉下不同种类蔬菜生长的影响%Effect of substrate culture on the growth of different vegetables under brackish water irrigation

    Institute of Scientific and Technical Information of China (English)

    翟红梅; 董宝娣; 乔匀周; 师长海; 杨静; 李东晓; 刘月岩; 刘孟雨

    2013-01-01

      环渤海区淡水资源匮乏,咸水资源丰富,为解决水资源短缺以及微咸水灌溉引起土壤盐渍化问题,研究了在微咸水灌溉条件下,基质栽培对番茄、青椒和茄子生长发育的影响,以土壤栽培为对照,基质为腐熟秸秆、珍珠岩和炉渣按质量比1∶1∶1混合,深30 cm ,整个生育期灌溉3 g・L-1微咸水。结果表明:基质栽培条件下番茄和茄子的生长发育受到显著抑制,相对于土壤栽培,株高分别下降44.1%和25.1%,生物量分别下降80.4%和48.9%,产量下降49.2%和27.6%;青椒的株高和生物量下降15.2%和27.0%,但是产量没有显著变化。通过测定基质和土壤的盐分,发现在基质栽培条件下蔬菜受到盐分胁迫,植株耐盐性能降低,细胞膜完整性被破坏,导致番茄、青椒和茄子的光合速率分别下降18.5%、15.3%和14.1%。可见这种基质栽培条件适宜于浅根系作物,不适宜深根系作物,并且基质材料应该选择不含有盐碱土的炉渣。%Bohai Sea region has plenty of brackish water but short of freshwater resources .In attempt to find the so-lution to solve the problems of freshwater shortages and soil salinization caused by brackish water irrigation ,we studied the effect of substrate culture on the growth of tomato ,green pepper and eggplant under brackish water irrigation .The substrate used in this study was made of composting straw ,perlite ,and slag mixed in a mass ratio of 1∶1∶1 .The depth of groove was 30 cm .All vegetables were irrigated with 3 g・L-1 saline water .The results showed the growth and devel-opment of tomato and eggplant was significantly inhibited in substrate culture .Compared with soil cultivation ,the plant height of tomato and eggplant were decreased 44 .1% and 25 .1% respectively ,the biomass was decreased 80 .4% and 48 .9% ,respectively ,and the yield was decreased 49 .2% and 27

  6. Produção de girassol ornamental com uso de águas salobras em sistema hidropônico NFT Production of ornamental sunflower with use of brackish waters in NFT hydroponic system

    Directory of Open Access Journals (Sweden)

    Marlo P Maciel

    2012-02-01

    Full Text Available Plantas de girassol ornamental 'Sol Vermelho' foram cultivadas em hidroponia com o objetivo de avaliar o uso de águas salobras sobre seu rendimento e qualidade da inflorescência. As águas salobras foram usadas para preparar a solução nutritiva e repor as perdas por evapotranspiração. O experimento foi conduzido em delineamento inteiramente aleatorizado com cinco níveis de salinidade da água: 1,51; 2,56; 3,86 e 6,19 dS m-1, obtidos pela adição de NaCl na água doce local (0,47 dS m-1 que também foi usada como testemunha. Cada tratamento foi repetido quatro vezes e cada parcela (com quatro plantas foi construída para simular um sistema independente da técnica do fluxo laminar de nutrientes (NFT. Observou-se uma redução linear causada pelo aumento da salinidade da água sobre a altura das plantas, o diâmetro do caule e a massa da matéria seca da parte aérea. Tanto a altura da planta quanto o diâmetro do caule foram reduzidos em 3,2% e a massa de matéria seca da parte aérea foi reduzida em 5,78% (dS m-1-1, para cada acréscimo unitário da salinidade da água (dS m-1. Por outro lado, a salinidade da água não afetou o tamanho do capítulo do girassol e não foram registrados sintomas de toxicidade causados pela salinidade. Esses resultados sustentam a viabilidade técnica do uso de águas salobras para produção hidropônica de girassol ornamental.Plants of ornamental sunflower 'Sol Vermelho' were grown under hydroponic conditions aiming to evaluate the effects of use of brackish water on its yield and inflorescence (capitulum quality. The brackish waters were utilized to prepare nutrient solution and to replace water due to evapotranspiration loss. The experiment was carried out in a completely randomized experimental design with five levels of water salinity: 1.51; 2.56; 3.86 and 6.19 dS m-1, obtained by addition of NaCl to local fresh water; this fresh water (0.47 dS m-1 was also studied as control treatment. Each

  7. The genus Perissocytheridea Stephenson, 1938 (Crustacea: Ostracoda) and evidence of brackish water facies along the Oligo-Miocene, Pirabas Formation, eastern Amazonia, Brazil

    Science.gov (United States)

    Evangelista Nogueira, Anna Andressa; Ramos, Maria Inês Feijó

    2016-01-01

    Perissocytheridea Stephenson is characteristic of brackish water facies. In 57 samples from the Upper Oligocene to Lower Miocene, from five localities, Pirabas Formation, Pará State, Brazil eleven species have been identified. Among these species, four are new reports: Perissocytheridea punctoreticulata n. sp., Perissocytheridea largulateralis n. sp., Perissocytheridea colini n. sp. and Perissocytheridea pirabensis n. sp.; five species in open nomenclature: Perissocytheridea sp. 1, P. sp. 2, P. sp. 3, P. sp. 4, and P. sp. 5 and two species left in "aff." abbreviation: Perissocytheridea aff. Perissocytheridea pumila and Perissocytheridea aff. Perissocytheridea brachyforma subsp. excavata. The distributional pattern of the Perissocytheridea combined with the occurrence of foraminifera Elphidium and Ammonia in the studied sections supports the presence of the brackish water facies to the respective layers. Their quantitative variation through the studied sections indicate more than one phase of salinity reduction (about >5 and genus has a wide paleobiogeographical occurrence and stratigraphic distribution ranging from the Cretaceous to Recent, and already been recorded in the northern of South America, especially in the Neogene of Solimões Basin, but this is the first report of a neotropical genus to the Oligo-Miocene deposits of Pirabas Formation, northern Brazilian Coast, Pará State.

  8. The role of plant functional groups in methane dynamics in a boreal fen under pristine and water level drawdown conditions

    Science.gov (United States)

    Riutta, T.; Tuittila, E.-S.; Laine, J.

    2012-04-01

    Vegetation and hydrology are important controlling factors in peatland methane dynamics. Vegetation structures (i.e. species composition, physiognomy, density) and productivity are strongly interlinked with moisture conditions (water table level variation), and the methane flux is a result of the vegetation-water table interaction, rather than a direct effect of water table or vegetation. Therefore, observational studies in pristine peatlands have a limited ability to separate the effects of these factors. This study aimed to experimentally quantify the role of the fen ecosystem components - sedges, dwarf shrubs, Sphagnum mosses, and the underlying peat - in methane fluxes in control and experimental water table drawdown conditions and to separate the plant-mediated effects from the effect of altered water table level on methane fluxes. We carried out the experiment in a boreal nutrient-poor fen using two treatments: a vegetation component removal treatment with four levels and a water level treatment with two levels (control and a 15 cm water level draw down). We measured methane fluxes during four growing seasons using a static chamber technique. The first year was a calibration season preceding the water level drawdown treatment. Based on the vegetation removal treatments, plant-mediated fluxes comprised 75% of the total cumulative growing season methane flux (7.8 ± 0.83 g CH4 m-2 from June to September) in the control water level conditions. Sedge and Sphagnum moss mediated fluxes accounted for 48% and 27% of the total flux, respectively. The presence of dwarf shrubs, on the other hand, had a slightly attenuating effect on the fluxes. In water level drawdown conditions, fluxes were significantly lowered (cumulative growing season flux 0.12 ± 0.10 g CH4 m-2) and the presence / absence of the plant groups had hardly any effect on the fluxes. There was a tight, positive relationship between net ecosystem production and methane flux in the control conditions but

  9. Branchial Na+:K+:2Cl− cotransporter 1 and Na+/K+-ATPase α-subunit in a brackish water-type ionocyte of the euryhaline freshwater white-rimmed stingray, Himantura signifer

    OpenAIRE

    YuenKIp; JonathanMWilson; ShitFChew

    2013-01-01

    Himantura signifer is a freshwater stingray which inhabits rivers in Southeast Asia. It can survive in brackish water but not seawater. In brackish water, it becomes partially ureosmotic, but how it maintains its plasma hypoionic to the external medium is enigmatic because of the lack of a rectal gland. Here, we report for the first time the expression of Na+:K+:2Cl− cotransporter 1 (nkcc1) in the gills of freshwater H. signifer, and its moderate up-regulation (~2-fold) in response to brackis...

  10. Excluding the di-unsaturated alkenone in the UK37 index strengthens temperature correlation for the common lacustrine and brackish-water haptophytes

    Science.gov (United States)

    Zheng, Yinsui; Huang, Yongsong; Andersen, Robert A.; Amaral-Zettler, Linda A.

    2016-02-01

    Alkenone unsaturation indices, represented by either UK37 or UK‧37, are important tools for paleoclimate studies. The UK37 index is a reflection of the average number of double bonds from di-, tri-, tetra-unsaturated alkenones, but UK‧37 excludes the C37:4 in the calculation. Extensive studies indicate UK‧37 provides better regressions against in situ Sea Surface Temperatures (SST) than UK37 and is the most widely used SST proxy. However, recent studies have shown that including C37:4 alkenones for lacustrine or brackish water haptophytes such as Ruttnera (Chrysotila) lamellosa and Isochrysis galbana improves temperature correlations although there are still significant deviations at the extreme high and low temperatures. In this study, we use new culture-based calibration experiments alongside published culture data and in situ water column or surface sediment data, to demonstrate that a further improved temperature calibration for alkenones is, in fact, achieved when the di-unsaturated alkenone is excluded from the computation of the unsaturation index. We propose new indices, termed UK″ [UK″37 = C37:3/(C37:3 + C37:4) or UK″38 = C38:3/(C38:3 + C38:4)], for lacustrine, brackish and estuarine waters. Our observation suggests that di-unsaturated alkenones play a less important role than tri- and tetra-unsaturated alkenones in regulating cell functions to temperature variations in lacustrine and brackish waters. We suggest using UK″ indices for paleotemperature reconstructions in the lacustrine and estuarine settings.

  11. Carbon fractions and stocks in organic layers in boreal forest soils—impacts of climatic and nutritional conditions

    OpenAIRE

    Hilli, S. (Samu)

    2011-01-01

    Abstract The SOM in boreal forests contains non-living heterogeneous components resulting from microbial and chemical transformations of organic debris from plant litter. The major components in the plant biomass all decompose at different rates and therefore, contribute variably to the stable storages of soil C. The aims of the current thesis were 1) to explore how climate, soil fertility and initial litter quality affect the decomposition rate of litter, 2) to study how the different ca...

  12. Meteorological pre-processing of incoming solar radiation and heat flux over a sparse boreal forest at a northern site during winter conditions

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Batchvarova, E.

    2001-01-01

    Measurements from Northern Finland on radiation and turbulent fluxes over a sparse boreal forest with snow-covered ground were analysed. The measurements represent harsh winter conditions characterized by low sun angles. The absorption of incoming solar radiation in clear skies (turbidity) was...... found to be a strong function of the solar elevation. At low solar elevation angles, commonly used expressions for turbidity did not fit the measurements well. A simple energy balance type met-processor performed well during daytime, but it was not satisfactory during night time. Simplifications and...

  13. Snow conditions and usability value of pastureland for semi-domesticated reindeer (Rangifer tarandus tarandus in northern boreal forest area

    Directory of Open Access Journals (Sweden)

    Jouko Kumpula

    2009-01-01

    Full Text Available We studied variation in snow conditions and selection of pasture area according to altitude by semi-domesticated reindeer (Rangifer tarandus tarandus during 1999 - 2002 in a pine forest area utilised by forest industry in the Ivalo reindeer herding district, northern Finland. Snow conditions were measured over the course of three winters along equilateral triangles (side 3.5 km for three times per winter. The altitudinal selection of pasture area by reindeer was studied using GPS tracking data (10 977 locations from 29 female reindeer. We observed that interannual weather variation mostly affected the depth, density and hardness of snow in the study area. At the forest landscape level, snow depth and density increased with altitude. Thinnest and deepest snow cover occurred on western and northern slopes, respectively. In contrast, forest harvesting did not seem to affect snow conditions. From spring to autumn, reindeer mainly used higher altitudes in pastures. In early and mid-winter, when snow conditions were easy or moderate reindeer still preferred higher altitudes, but in late winter when snow conditions and food accession were at their most difficult, they preferred lower altitudes. We conclude that especially the use of high elevation forestland pastures may become more difficult for reindeer if the global climatic change causes higher winter precipitation to the northern boreal forest area. In general, the low-elevation forestland areas have primary winter grazing value for reindeer but these areas are also intensively used by forest industry.Abstract in Finnish / Tiivistelmä:Lumiolosuhteet ja laidunten käyttöarvo poronhoidossa pohjoisella havumetsäaluella Lumiolosuhteiden vaihtelua ja porojen (Rangifer tarandus tarandus laidunalueen valintaa maaston korkeuden perusteella tutkittiin vuosina 1999–2002 metsätalouden hyödyntämällä mäntymetsäalueella Ivalon paliskunnassa, Pohjois-Suomessa. Lumiolosuhteet mitattiin kolme kertaa

  14. Adaptive alterations on gill Na(+), K(+)-ATPase activity and mitochondrion-rich cells of juvenile Acipenser sinensis acclimated to brackish water.

    Science.gov (United States)

    Zhao, Feng; Wu, Beibei; Yang, Gang; Zhang, Tao; Zhuang, Ping

    2016-04-01

    Understanding the physiological changes and osmoregulatory strategy is critical for anadromous species to adapt to large changes between freshwater and marine environments. In this study, juvenile Chinese sturgeon (Acipenser sinensis) were acclimated for 2 months to freshwater (FW, c. 0 ‰) and brackish water (BW, 15 ‰). Blood was assessed for changes in osmolality and ions. Gill tissue was assayed for Na(+), K(+)-ATPase (NKA) activity and immunohistochemical analysis on mitochondria-rich cells (MRCs). Serum osmolality and ions concentrations (Na(+), Cl(-) and K(+)) examined, except K(+), increased significantly in those specimens adapted to BW. However, the variations were within the range of effective hyperosmotic adaptation. The specific activity of gill NKA of juveniles adapted to BW was significantly higher (c. 1.6 times) than that of fish adapted to FW. MRCs were mainly presented in the interlamellar region of the filament and at the base of the lamella in either FW- or BW-acclimated individuals. In BW, the number and size of MRCs on filaments greatly increased. However, there was no significant difference in the number and size of the MRCs at the lamella region. Results show that juvenile Chinese sturgeon keep osmotic homeostasis in hyperosmotic environments by increasing gill NKA activity and MRCs' size and number, which is similar to other sturgeons and euryhaline teleosts. PMID:26614501

  15. Controls on variations in MODIS fire radiative power in Alaskan boreal forests: implications for fire severity conditions

    Science.gov (United States)

    Barrett, Kirsten; Kasischke, Eric S.

    2013-01-01

    Fire activity in the Alaskan boreal forest, though episodic at annual and intra-annual time scales, has experienced an increase over the last several decades. Increases in burned area and fire severity are not only releasing more carbon to the atmosphere, but likely shifting vegetation composition in the region towards greater deciduous dominance and a reduction in coniferous stands. While some recent studies have addressed qualitative differences between large and small fire years in the Alaskan boreal forest, the ecological effects of a greater proportion of burning occurring during large fire years and during late season fires have not yet been examined. Some characteristics of wildfires that can be detected remotely are related to fire severity and can provide new information on spatial and temporal patterns of burning. This analysis focused on boreal wildfire intensity (fire radiative power, or FRP) contained in the Moderate Resolution Imaging Spectroradiometer (MODIS) daily active fire product from 2003 to 2010. We found that differences in FRP resulted from seasonality and intra-annual variability in fire activity levels, vegetation composition, latitudinal variation, and fire spread behavior. Our studies determined two general categories of active fire detections: new detections associated with the spread of the fire front and residual pixels in areas that had already experienced front burning. Residual pixels had a lower average FRP than front pixels, but represented a high percentage of all pixels during periods of high fire activity (large fire years, late season burning, and seasonal periods of high fire activity). As a result, the FRP from periods of high fire activity was less intense than those from periods of low fire activity. Differences related to latitude were greater than expected, with higher latitudes burning later in the season and at a higher intensity than lower latitudes. Differences in vegetation type indicate that coniferous vegetation

  16. Novel in situ multiharmonic EQCM-D approach to characterize complex carbon pore architectures for capacitive deionization of brackish water

    International Nuclear Information System (INIS)

    Multiharmonic analysis by electrochemical quartz-crystal microbalance with dissipation monitoring (EQCM-D) is introduced as an excellent tool for quantitative studying electrosorption of ions from aqueous solution in mesoporous (BP-880) or mixed micro-mesoporous (BP-2000) carbon electrodes. Finding the optimal conditions for gravimetric analysis of the ionic content in the charged carbon electrodes, we propose a novel approach to modeling the charge-dependent gravimetric characteristics by incorporation of Gouy-Chapman-Stern electric double layer model for ions electrosorption into meso- and micro-mesoporous carbon electrodes. All three parameters of the gravimetric equation evaluated by fitting it to the experimental mass changes curves were validated using supplementary nitrogen gas sorption analysis and complementing atomic force microscopy. Important overlap between gravimetric EQCM-D analysis of the ionic content of porous carbon electrodes and the classical capacitive deionization models has been established. The necessity and usefulness of non-gravimetric EQCM-D characterizations of complex carbon architectures, providing insight into their unique viscoelastic behavior and porous structure changes, have been discussed in detail. (paper)

  17. Novel in situ multiharmonic EQCM-D approach to characterize complex carbon pore architectures for capacitive deionization of brackish water.

    Science.gov (United States)

    Shpigel, Netanel; Levi, Mikhael D; Sigalov, Sergey; Aurbach, Doron; Daikhin, Leonid; Presser, Volker

    2016-03-23

    Multiharmonic analysis by electrochemical quartz-crystal microbalance with dissipation monitoring (EQCM-D) is introduced as an excellent tool for quantitative studying electrosorption of ions from aqueous solution in mesoporous (BP-880) or mixed micro-mesoporous (BP-2000) carbon electrodes. Finding the optimal conditions for gravimetric analysis of the ionic content in the charged carbon electrodes, we propose a novel approach to modeling the charge-dependent gravimetric characteristics by incorporation of Gouy-Chapman-Stern electric double layer model for ions electrosorption into meso- and micro-mesoporous carbon electrodes. All three parameters of the gravimetric equation evaluated by fitting it to the experimental mass changes curves were validated using supplementary nitrogen gas sorption analysis and complementing atomic force microscopy. Important overlap between gravimetric EQCM-D analysis of the ionic content of porous carbon electrodes and the classical capacitive deionization models has been established. The necessity and usefulness of non-gravimetric EQCM-D characterizations of complex carbon architectures, providing insight into their unique viscoelastic behavior and porous structure changes, have been discussed in detail. PMID:26902741

  18. The impact of fish predation on shallow soft bottoms in brackish waters (SW Finland); an experimental study

    Science.gov (United States)

    Mattila, J.; Bonsdorff, E.

    The impact of fish predation on shallow soft bottoms was studied by field and laboratory experiments. The field manipulations (caging experiments) were carried out in 2 shallow (1.5 m) bays in the northern Baltic Sea. An a priori hypothesis that fish do not structure macrozoobenthic communities in shallow soft-bottom areas was tested. Short-term aquarium experiments clearly showed that perch ( Perca fluviatilis L.), roach ( Rutilus rutilus L.) and ruffe ( Acerina cernua (L.)) are all effective predators on benthic macroinvertebrates ( Corophium volutator) Pallas and Nereis diversicolor O.F. Müller) under laboratory conditions. Thus fish can be considered a potential structuring force on benthic communities in shallow soft-bottom areas. Caging experiments of one to two month's duration (partial and total exclosure of fish and enclosure with perch) induced only minor changes in the benthic community. These results support the a priori hypothesis. One of our main conclusions is, however, that fish predation and other biotic interactions (competition, disturbance, etc.) together with abiotic factors play some role in the structuring processes. Multilevel testing is needed in studies on biotic interactions in the marine environment. Results from a specific environment should not automatically be applied to other kinds of habitats.

  19. Aquaculture, Salt and Brackish Water, Rhode Island Aquaculture Locations; Point Locations for Aquaculture operations in Narragansett Bay and the coastal ponds of Rhode Island., Published in 2005, 1:7200 (1in=600ft) scale, State of Rhode Island and Providence Plantations.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Aquaculture, Salt and Brackish Water dataset, published at 1:7200 (1in=600ft) scale, was produced all or in part from Hardcopy Maps information as of 2005. It...

  20. Aquaculture, Salt and Brackish Water, The G-WIS data are created to support environmental assessments associated with oil and gas exploration, production, and transportation activities in the Gulf of Mexico., Published in 2001, 1:24000 (1in=2000ft) scale, Louisiana State University.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Aquaculture, Salt and Brackish Water dataset, published at 1:24000 (1in=2000ft) scale as of 2001. It is described as 'The G-WIS data are created to support...

  1. Preliminary design of seawater and brackish water reverse osmosis desalination systems driven by low-temperature solar organic Rankine cycles (ORC)

    International Nuclear Information System (INIS)

    In this paper, the coupling between the low-temperature solar organic Rankine cycle (ORC) and seawater and brackish water reverse osmosis desalination units has been carried out. Four substances have been considered as working fluids of the solar cycle (butane, isopentane, R245fa and R245ca). With these four fluids the volumetric flow of fresh water produced per unit of aperture area of stationary solar collector has been calculated. The former has been made with the optimized direct vapour generation (DVG) configuration and heat transfer fluid (HTF) configuration of the solar ORC. In the first one (DVG), working fluid of the ORC is directly heated inside the absorber of the solar collector. In the second one (HTF), a fluid different than the working fluid of the ORC (water in this paper) is heated without phase change inside the absorber of the solar collector. Once this fluid has been heated it is carried towards a heat exchanger where it is cooled. Thermal energy delivered in this cooling process is transferred to the working fluid of the ORC. Influence of condensation temperature of the ORC and regeneration's process effectiveness over productivity of the system has also been analysed. Finally, parameters of several preliminary designs of the low-temperature solar thermal driven RO desalination are supplied. R245fa is chosen as working fluid of the ORC in these preliminary designs. The information of the proposed preliminary designs can also be used, i.e., for the assessment of the use of thermal energy rejected by the solar cycle. Overall analysis of the efficiency of the solar thermal driven RO desalination technology is given with the results presented in this paper and the results obtained with the medium temperature solar thermal RO desalination system presented by the authors in previous papers. This work has been carried out within the framework of the OSMOSOL and POWERSOL projects.

  2. Host-dependent variations in the seasonal prevalence and intensity of heterophyid encysted metacercariae (Digenea: Heterophyidea) in brackish water fish in Egypt.

    Science.gov (United States)

    Elsheikha, Hany M; Elshazly, Attef M

    2008-05-01

    The prevalence of heterophyid (Digenea: Heterophyidae) encysted metacercariae (EMC) in its second intermediate host, the fish Mugil spp. and Tilapia spp. was studied in a subtropical permanent Lake in northeastern Egypt. Seasonal changes in the occurrence of the EMC in different fish hosts were monitored in a longitudinal field survey lasting 12 months from June 2006 to May 2007. This study tested two hypotheses; (i) prevalence and intensity of heterophyid EMC fluctuate seasonally throughout the year and (ii) variation in the prevalence and intensity of heterophyid EMC is host-dependent. A total of 832 fish specimens comprising 5 species collected from Manzala Lake, northeastern Egypt were examined by artificial gastric juice digestion for EMC. All five species of brackish water fish examined were found to harbor the EMC of the family Heterophyidae in their muscles. The overall infection prevalence of EMC over 12 months was 23.2%. The adult flukes recovered from puppies experimentally infected with morphologically different metacercariae from different fish species were compatible with six species belong to five genera of Heterophyidae, namely, Heterophyes heterophyes, Heterophyes aequalis, Pygidiopsis genata, Phagicola sp., Haplorchis sp. and Stictodora sp. EMC of H. heterophyes were most abundant, detected in 56% of the total fish examined. P. genata was ranked second, followed by Phagicola sp., H. aequalis, Haplorchis sp., and Stictodora sp., respectively. Seasonal differences in infection were observed for all heterophyid species studied in all fish species examined. Heterophyid infections reached peak prevalences during the summer season 38.2% followed by spring 26.6% and autumn 19.3% seasons, whereas the lowest prevalence was recorded in the winter 8.7%. Intensity of heterophyid EMC followed the same seasonal pattern, being high during summer months and low in winter months. All fish species were infected with all the heterophyid digeneans, but with different

  3. Morphological Analysis of Anopheles vagus Donitz, 1902 (Diptera : Culicidae in fresh water and brackish water habitats = Variasi Morfologi Anopheles vagus Donitz, 1902 (Diptera : Culicidae dari Habitat Air Tawar dan Air Payau

    Directory of Open Access Journals (Sweden)

    Siti Alfiah

    2014-10-01

    Full Text Available ENGLISHAbstractAnopheles subpictus had habitat variation and showed genetic difference. So, the variation of habitat of An. vagus may support the hypothesa that An. vagus had genetic and morphology variation, same as An. subpictus.The aimed of this research was analyze morphology and chaetotaxy difference between An. vagus in fresh water and brackish water. The subject of the study was An. vagus collected from Kesongo Village, Tuntang Subdistrict, Semarang (fresh water and Jatimalang Village, Purwodadi Subdistrict, Purworejo (brackish water. Anopheles vagus were collected and individually reared. One sample in every batch was used to make larvae skin, pupae skin and adult specimen of An. vagus. The result showed that there were intra and inter population variation between An. vagus in fresh water and brackish water. The variations were on the size and number of hair branches and filaments. The conclution of this research were the morphology and chaetotaxy of female An. vagus in fresh water and brackish water showed no different. Intra and interpopulation An. vagus in fresh water and brackish water were caused by the difference of geography location (allopatric speciation.INDONESIANVariasi habitat terjadi pada An. subpictus, variasi habitat yang berbeda menunjukkan variasi genetik yang berbeda. Oleh karena itu variasi habitat An. vagus diduga akan bepengaruh terhadap variasi genetik dan morfologi. Tujuan penelitian adalah menganalisis perbedaan morfologi dan kaetotaksi Anopheles vagus habitat air tawar dan air payau. Subyek penelitian adalah An. vagus habitat air tawar di Desa Kesongo, Kecamatan Tuntang, Kabupaten Semarang dan An. vagus habitat air payau di Desa Jatimalang, Kecamatan Purwodadi, Kabupaten Purworejo. Anopheles vagus yang diperoleh, di rearing secara individual. Tiap indukan diambil satu sampel keturunannya dan dibuat preparat skin larva, skin pupa dan nyamuk dewasa betina. Hasil menunjukkan bahwa Anopheles vagus betina habitat air

  4. Storm track activity over the North Pacific associated with the Madden-Julian Oscillation under ENSO conditions during boreal winter

    Science.gov (United States)

    Takahashi, Chiharu; Shirooka, Ryuichi

    2014-09-01

    The present study investigates modulation by the Madden-Julian Oscillation (MJO) of storm track activity (STA) over the North Pacific (NP) during boreal winter for El Niño and La Niña periods. STA defined by vertically averaged synoptic eddy kinetic energy (EKE) greatly intensifies over the western North Pacific (WNP) and central eastern North Pacific during La Niña and El Niño years, respectively, when the MJO convection is located over the central Indian Ocean (IO)-Maritime Continent. When the MJO moves into the western central Pacific, the STA in La Niña years is suppressed (enhanced) at higher (lower) latitudes than in El Niño years. Diagnoses of EKE and eddy available potential energy budgets indicate that the difference in STA over the WNP for the MJO phases between El Niño-Southern Oscillation (ENSO) years is mainly contributed by baroclinic energy conversion and potential energy conversion between background and eddy (BCPE). We reveal that BCPE is mainly attributed to intraseasonal baroclinicity and eddy heat flux (EHF) anomalies and their interactions with strong winter mean baroclinic fields in the WNP. Through the EHF, synoptic eddies act to counterbalance an intraseasonal temperature that is primarily caused by the anomalous horizontal advection of mean temperature by MJO-related flow. The intraseasonal circulation and associated temperature and EHF anomalies dominate in northwest (southeast) portion of the NP during La Niña (El Niño), leading to BCPE difference. Changes in the spatial pattern and strength of the NP circulation and STA are caused by dominance of strong MJO amplification over the IO (central Pacific) during La Niña (El Niño).

  5. Variation in Salt Content of Heavily-textured Coastal Saline Soils Leached by Brackish Water%微咸水淋洗重壤质滨海盐土的盐分变化研究

    Institute of Scientific and Technical Information of China (English)

    廉晓娟; 李明悦; 王艳; 张余良; 王立艳; 王正祥

    2011-01-01

    In order to save fresh water resource, it was necessary to explore and utilize reasonably brackish water replacing fresh water to improve saline soils, the author investigated the desalination effect of heavily-textured coastal saline soils leached by brackish water in field plot experiment. The results showed that in the well drained soils, using the brackish water with salinity of 3.5 g/L could lead to a fast and mark desalination effect. Taking saving water and desalination effect into account, the author suggested that an optimal leaching method was to sequentially leaching soil for three times with 1200 m3/hm2 brackish water. This method could decreased total salt content of soil (0-60 cm) to 3 g/kg and even below, make the desalination ratio to 60%, so that soil salt content met the requirement of common landscape plants.%为了节约淡水资源,合理开发利用微咸水代替淡水来改良盐碱地土壤.采用野外小区试验的方法,对不同灌水条件下滨海盐土土壤的脱盐效果进行分析.结果表明:在良好的排水条件下,采用矿化度约3.5 g/L的微咸水淋洗滨海盐土,能使土壤迅速脱盐,脱盐效果明显.综合节水和脱盐效果双重考虑,微咸水淋洗重壤质滨海盐土,以淋洗量1200 m3/hm2,连续淋洗3次为适宜的淋洗方式,能使0~60 cm土壤剖面的全盐量降低到3 g/kg以下,脱盐率达60%以上,土壤盐分含量达到一般绿化植物的生长要求.

  6. Progress in Investigation and Application of High Recovery Brackish Water Membrane Desalination Technology%高回收率膜法苦咸水淡化工艺的应用研究进展

    Institute of Scientific and Technical Information of China (English)

    宋跃飞; 苏现伐; 周建国; 苏保卫; 高从堦

    2015-01-01

    膜法苦咸水淡化过程中,符合环境保护要求的浓排水处理方法成本高昂,所以只有当回收率达到较高值时,在实际运行中才具有经济可行性。目前,在不加剧膜污染的条件下进一步提高苦咸水淡化系统回收率的方法已成为该领域研究热点。本文详细综述了高回收率膜法苦咸水淡化工艺的应用研究进展,包括基于反渗透、纳滤、正渗透、膜蒸馏、电渗析和电容去离子化淡化工艺过程,以及这些过程面临的热点问题,并对此提出了建议。%The costs of environmentally responsible brine disposal methods at inland sites can be prohibitively expensive in membrane brackish water desalination processes. As a result, it is often economically infeasible to develop such ground water sources unless very high product water recovery is attained. High product water recovery in membrane desalination processes is often limited by scaling of sparingly soluble salts when the concentrate above the solubility limits in the highly concentrated brine. Therefore, attempt was currently made to solve or mitigate scaling of membrane for brackish water desalination while remaining or further increasing overall system product water recovery. In this paper, the progress in improving the recovery of brackish water desalination by membrane technology including reverse osmosis (RO), nanofiltration (NF), forward osmosis (FO), membrane distillation (MD), electrodialysis (ED) and capacitive deionization (CDI), the scaling problem therein, as well as critical issues existing in this region were presented and commented extensively. In addition, the problems and suggestions for the current research status are proposed.

  7. 微咸水灌溉对斥水土壤水盐运移的影响%Effect of brackish water irrigation on water and salt movement in repellent soils

    Institute of Scientific and Technical Information of China (English)

    刘春成; 李毅; 郭丽俊; 关冰艺; 廖轶群; 王娟

    2011-01-01

    The existence of soil water-repellency had impacts on crop yields. In order to study soil water and salt movements of water-repellent soils irrigated by brackish water, laboratory soil column infiltration experiments were conducted. Impacts of different mineralization degrees and different water-repellency degrees on the movements of soil water and soil salt were compared for two soil textures. The variations of soil water-repellency during infiltration were also discussed. The results showed that infiltration ability of non-water-repellent soils increased with the increase of mineralization degrees. Both the infiltration rates of wettable and repellent soils could be simply fitted by Kostiakov equation. For the water repellent soils, the infiltration ability was largest at mineral degree of lg/L, but decreased with the increase of mineralization degree when mineralization degree were larger than lg/L. There was good linear relationship between cumulative infiltration and the wetting front distance when irrigated by brackish water. Soil water content and soil salt content at the same depth of the water repellent soil profiles were smaller than those of the wettable soil profiles. To some extent, soil water repellency was caused after irrigated by brackish water. This work indicated that brackish water irrigation had some impacts on distributions of soil water and soil salt as well as water-repellency of salinized soil.%土壤斥水性影响着作物的产量,为了研究微成水灌溉对斥水土壤水盐运移的影响,进行了室内土柱微咸水入渗试验.对比了不同矿化度和斥水程度对两种土质水盐运移的影响,探讨了微咸水入渗后土壤斥水性的变化特征.结果表明,不斥水土壤的入渗能力随矿化度的增加而增加.亲水和斥水土壤的入渗率均可采用Kostiakov公式简单模拟.斥水土壤入渗能力在矿化度为1g/L时达到最大,超过1 g/L后则随矿化度的增大而减小.微咸水入渗的

  8. Report on follow-up for joint research of valuable resources recovery techniques from brackish water; Kansuichu no yuka shigen kaishu gijutsu ni kansuru kenkyu kyoryoku follow up hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    This report describes follow-up for research and development on the recovery of valuable resources, such as magnesium, bromine and boron, contained in the brackish water for manufacture of common salt in the coastal region of Mexico. For the field survey, salt garden, irrigation plant and manufacturing plant of dinning salt were inspected. The optimum site was examined by assuming desalination plant and solar pond. The groundwater in coastal regions is progressively salified. Since the coastal region is a tourist resort with an round-trip area of whales, environmental protection is indispensable. For the joint research with invited researchers, the solar pond system and fresh water generation were studied. As a result, it was found that the solar pond system is an excellent method for keeping thermal energy in a low cost at the salt garden with abundant solar energy, and that the desalination system combined with distilling is the most suitable method. 7 refs., 8 figs., 1 tab.

  9. Effects of PAM on Characteristics of Water and Salt Movement in Soil under Brackish Water Infiltration%微咸水入渗下施加PAM土壤水盐运移特性研究

    Institute of Scientific and Technical Information of China (English)

    王全九; 张继红; 谭帅

    2016-01-01

    土壤改良剂与微咸水灌溉相结合,对于合理开发利用微咸水、改善盐碱土结构及促进作物生长有着重要意义。基于一维垂直土柱积水入渗和水平土柱吸渗试验,研究了微咸水入渗条件下,不同聚丙烯酰胺(polyacrylamide,PAM)施量(0、0.02%、0.04%和0.06%)对盐碱土水盐运移特性的影响。结果表明:(1)微咸水入渗条件下,施加PAM能够降低土壤入渗速率,增加土壤保水性能。(2)施加PAM对Philip及Kostiakov入渗模型参数有显著影响,在PAM施量0.04%时,吸渗率S和经验系数K最小,而经验指数β最大。(3)在PAM施量为0.04%时,土壤饱和体积含水量最大,Brooks-Corey模型进气吸力hd增加了15.30%,土壤持水性能显著提高;土壤水分扩散率最小,水分分布最均匀。(4)施加PAM能够显著提高土层的持水效率和微咸水的淋洗效果,在PAM施量为0.04%时,土层持水效率最高,盐分淋洗量最大。%It is of great significance to use soil amendment in combination with brackish water irrigation in rationalizing the exploitation of brackish water,improving saline soil structure and promoting crop growth. Polyacrylamide(PAM),a kind of organic polymer material,is regarded as an effective soil amendment because of its strong water holding capacity. In this paper,ponding infiltration experiments on one-dimension vertical soil columns and absorbing infiltration experiments on horizontal soil columns were carried out for investigation of effect of PAM application rate(0,0.02%,0.04% and 0.06%)on water and salt movement in soils with brackish water. Results show that(1)PAM reduced soil infiltration rate and enhanced soil water retention capability in the soil under brackish water infiltration,and the soil amended with 0.04% PAM was the highest in soil water retention capability;(2)PAM application significantly affected the parameters of the Philip and Kostiakov infiltration

  10. Relevant factors for membrane fouling in brackish water reverse osmosis desalination%苦咸水反渗透淡化中影响膜面的污染因素∗

    Institute of Scientific and Technical Information of China (English)

    宋跃飞; 李铁梅; 周建国; 苏保卫; 高从堦

    2015-01-01

    Fouling phenomenon, type and degree in brackish water reverse osmosis ( BWRO ) desalination are significantly different from seawater reverse osmosis ( SWRO) process, due to the complex components of brackish water in different regions and the higher concentrate factor ( CF ) value in the majority of BWRO processes. Currently, membrane fouling as one of the bottlenecks for the large⁃scale BWRO application, has attracted in creasing attentions. In this review, overseas and domestic research progresses in application factors influencing the fouling on membrane surface in BWRO desalination were summarized in detail. The fouling components, fouling potential and quality indicators in water resources, and the physical properties influencing membrane fouling were introduced respectively. Two types of pretreatment methods including conventional and membrane technology were analysed, and the advantage of consistently high quality independent of influent associated with for membrane pretreatment was pointed out. In addition, the problems and suggestions for the current research status were proposed.%由于苦咸水的化学组成和浓度分布在不同地区有着显著的差异,以及淡化工艺中普遍较高的浓缩因子( concentrate factor, CF)值(在4—10之间),苦咸水反渗透( brackish water reverse osmosis, BWRO)淡化过程中的膜污染现象、类型和程度较海水反渗透( seawater reverse osmosis, SWRO)淡化过程有明显的不同。目前,膜污染已成为BWRO大规模应用于苦咸水淡化领域的瓶颈之一,如何解决这一问题成为该领域的研究热点。本文详细综述了国内外BWRO淡化过程中影响膜面污染因素的应用研究进展,重点介绍了进水来源污染成分及污染倾向、进水水质优劣指标和进水物性对膜面污染的影响;按照分离技术的不同,分类讨论了常规预处理和膜法预处理工艺,指出后者不易受进水水质变化的

  11. 正渗透—纳滤耦合处理苦咸水脱盐工艺%Technological Processes of Desalination Treatment for Brackish Water with Coupled Forward Osmosis-Nanofiltration System

    Institute of Scientific and Technical Information of China (English)

    时强; 张乾; 阮国岭; 初喜章

    2012-01-01

    Simulating 2 000 mg/L NaCl as brackish water, using divalent salt (Na2SO4, MgSO4, MgCl2 and their mixture solution) as draw solution, the water flux of forward osmosis(FO) for brackish water desalination was investigated. The nanofiltration (NF) performance for the recovery of draw solution was determined by software and experiment, and a dual NF process was designed for the recovery of diluted draw solution. Results show that the water flux of MgSO4 in FO process is lowest, and that of MgCl2 is highest. It is opposite in NF process that the NF performance of MgSO4 is best, and that of MgCl2 is worst. When the diluted draw solution of Na2SO4 is 30 g / L, it could be concentrated to the initial concentration (60 g/L) by a dual stage NF process, and the permeate TDS is lower than 500 mg/L.%以2000 mg/L氯化钠模拟苦咸水,采用二价无机盐作为汲取液,研究了正渗透淡化苦咸水时的水通量;通过软件计算和试验研究了不同组成汲取液的纳滤性能,并且设计了二级纳滤系统用于汲取液的回收.结果表明:相同浓度时硫酸镁汲取液正渗透水通量最低,而氯化镁汲取液水通量最高;相反在纳滤过程中,硫酸镁汲取液性能最佳,氯化镁最差;稀释硫酸钠汲取液浓度为30 g/L时,二级纳滤过程可以将汲取液浓缩至初始浓度(60g/L),并制得浓度低于500 mg/L的产水.

  12. Antioxidant Potential of Bark Extracts from Boreal Forest Conifers

    OpenAIRE

    Jean Legault; Karl Girard-Lalancette; Dominic Dufour; André Pichette

    2013-01-01

    The bark of boreal forest conifers has been traditionally used by Native Americans to treat various ailments and diseases. Some of these diseases involve reactive oxygen species (ROS) that can be prevented by the consumption of antioxidants such as phenolic compounds that can be found in medicinal plants. In this study, ultrasonic assisted extraction has been performed under various solvent conditions (water:ethanol mixtures) on the bark of seven boreal forest conifers used by Native American...

  13. Softwood biochar as a soil amendment material for boreal agriculture

    OpenAIRE

    Tammeorg, Priit

    2014-01-01

    Biochar is a porous carbonaceous solid material produced by pyrolysis. Application of biochar is considered as an efficient way of carbon (C) sequestration since the C in biochar is relatively resistant to microbial degradation. Furthermore, previous research in (sub-) tropical conditions suggests that it may enhance soil fertility and the yields of agricultural crops. To target the lack of knowledge about the effects of biochar in the boreal zone, softwood biochar was added to two boreal soi...

  14. 连续多年地下微咸水灌溉对食葵土壤养分和微生物的影响%The Effect of Consecutive Years with Brackish Water Irrigation on Soil Nutrients and Microorganisms in Sunflower Fields

    Institute of Scientific and Technical Information of China (English)

    郭永昌

    2012-01-01

    采用大田试验,以农十师种植面积最大的食葵为研究对象,研究了以4种不同量的微咸水灌溉对新疆食葵盐碱地的土壤理化性质和微生物特性的影响。结果表明:与渠水灌溉相比,连续多年微咸水灌溉使食葵土壤盐分积累和pH值升高,分别增加31.9%和12.6%,并且造成土壤有效养分降低,碱解氮、速效磷和速效钾分别降低了7.0%、12.4%和45.5%,而且微咸水灌溉明显减少了土壤微生物种群数量和土壤酶活性,因此,长期微咸水灌溉使土壤生物质量下降,不利于农田的持续利用。%A field experiment is carried out to study the effect of four concentrations of brackish water irrigation on physical and chemical properties of soil and microbial properties in sunflowers in the largest agricultural planting area in Xinjiang Production and Construction Corps Agricultural Division 10. The results show that total salt content and pH changes are significantly greater in soil receiving consecutive years with brackish water (P〈0. 05), compared with fresh water irrigation, total soil salt content and pH increase by 31.9% and 12.6%, respectively, and soil nutrients changes are significantly lower in soil receiving consecutive years with brackish water, nitrogen, available phosphorus and potassium are reduced by 7. 0%, 12.4% and 45.5% In the salt affected soil, the soil microbial population and soil enzyme activity are reduced. These results reveal that consecutive years with brackish water irrigation influences not only the chemical and physical characteristics of soils, but also soil biological properties. Therefore, the consecutive years with brackish water irrigation has important implications for soil health and sustainability in arid agricultural areas.

  15. Mineralization of cellulose in frozen boreal soils

    Science.gov (United States)

    Oquist, Mats G.; Segura, Javier; Sparrman, Tobias; Nilsson, Mats; Schleucher, Jurgen

    2015-04-01

    Soils of high-latitude ecosystems store a large fraction of the global soil carbon. In boreal forests, the microbial mineralization of soil organic matter (SOM) during winter can affect the ecosystems net carbon balance. Recent research has shown that microorganisms in the organic surface layer of boreal forest soil can mineralize and grow on simple, soluble monomeric substrates under frozen conditions. However, any substantial impacts of microbial activity in frozen soils on long-term soil carbon balances ultimately depends on whether soil microorganisms can utilize and grow the more complex, polymeric constituents of SOM. In order to evaluate the potential for soil microorganisms to metabolize carbon polymers at low temperatures, we incubated boreal forest soil samples amended with [13C]-cellulose and studied the microbial catabolic and anabolic utilization of the substrate under frozen and unfrozen conditions (-4 and +4°C). Freezing of the soil markedly reduced microbial utilization of the cellulose. The [13C]-CO2 production rate in the samples at +4°C were 0.52 mg CO2 SOM -1 day-1 while rates in the frozen samples (-4°C) were 0.01 mg CO2 SOM -1 day-1. However, newly synthetized [13C]-enriched cell membrane lipids, PLFAs, were detected in soil samples incubated both above and below freezing, confirming that cellulose can sustain also anabolic activity of the microbial populations under frozen conditions. The reduced metabolic rates induced by freezing indicate constraints on exoenzymatic activity, as well as substrate diffusion rates that we can attribute to reduced liquid water content of the frozen soil. We conclude that the microbial population in boreal forest soil has the capacity to metabolize, and grow, on polymeric substrates at temperatures below zero, which involves maintaining exoenzymatic activity in frozen soils. This capacity manifests the importance of SOM mineralization during the winter season and its importance for the net carbon balance of

  16. Ecological Sustainability of Birds in Boreal Forests

    OpenAIRE

    Lisa Venier; Mikko Mönkkönen; Robert Howe; Pekka Helle; JoAnn Hanowski; Gerald Niemi; Daniel Welsh

    1998-01-01

    We review characteristics of birds in boreal forests in the context of their ecological sustainability under both natural and anthropogenic disturbances. We identify the underlying ecological factors associated with boreal bird populations and their variability, review the interactions between boreal bird populations and disturbance, and describe some tools on how boreal bird populations may be conserved in the future. The boreal system has historically been an area with extensive disturbance...

  17. Study on brackish water treatment technology

    Institute of Scientific and Technical Information of China (English)

    HE Xu-wen(何绪文); Xu De-ping (许德平); WU Bing(吴兵); WANG Tong(王通)

    2003-01-01

    Based on the characters of deep well-water quality in Fenxi Mining Group in Liulin, the feasibilities of two treatment technologies which use electrodialysis and reverse osmosis are analyzed. Through analyzing and comparing, reverse osmosis technology has several advantages, such as good treatment effect, convenient operating management and low run-cost.

  18. Uso do rejeito da dessalinização de água salobra para irrigação da erva-sal (Atriplex nummularia The use of the brine from desalting brackish water to irrigate saltbush (Atriplex nummularia

    Directory of Open Access Journals (Sweden)

    Everaldo R. Porto

    2001-04-01

    Full Text Available Com o objetivo de se reduzir os impactos causados pela dessalinização de água salobra proveniente do cristalino no trópico semi-árido brasileiro, a erva-sal (Atriplex nummularia foi cultivada durante um ano, nos campos da Estação Experimental da Embrapa Semi-Árido. As plantas foram irrigadas com rejeito do processo de dessalinização, com concentração salina média de 11,38 dS m-1, e cada uma recebeu 75 L de água por semana, durante 48 semanas. A salinidade média do perfil de solo, da camada de 0 a 90 cm, era de 0,64 dS m-1 antes de se iniciar a irrigação das plantas; depois da colheita das plantas, a salinidade do mesmo perfil de solo foi de 12,74 dS m-1, enquanto a produtividade da erva-sal foi de 6.537,0 kg ha-1 de matéria seca, com teor de proteína bruta de 18,40% nas folhas. A Atriplex apresentou grande potencial de extração de sais do perfil de solo, mas quando as plantas são irrigadas com rejeito de alta concentração salina, a quantidade de sais extraída desse perfil pela planta, é da ordem de 3,93% do total de sais adicionados ao solo pelas irrigações; isto implica no fato de que, para um manejo de água sustentável, há necessidade de se gerar mais informações sobre as relações de solo e água para a erva-sal, nas condições das zonas áridas do Brasil.Looking forward to reducing environmental impacts resulting from desalting brackish water in the region of the crystalline rocks in the semi-arid tropic of Brazil, saltbush (Atriplex nummularia was cultivated during one year in an experimental field of Embrapa Semi-Arid. The plants were irrigated with the brine from the desalting plant which presented a salt concentration of 11.38 dS m-1. Each plant received 75 L of water per week, during 48 weeks. The soil salinity, at the depth of 0-90 cm, of the cropped area averaged 0.64 dS m-1 before starting the irrigation process. After the plants were harvested, the soil salinity in the same profile averaged 12.74 d

  19. Suitable culture conditions and cellular biochemical composition of three diatoms from brackish water%3种半咸水硅藻的适宜培养条件及其细胞生化成分

    Institute of Scientific and Technical Information of China (English)

    曾蓓蓓; 黄旭雄; 危立坤; 刘林林

    2014-01-01

    从上海奉贤一处半咸水池塘分离得到角毛藻(Chaetoceros sp.) SHOU-B98、小环藻(Cyclotella sp.)SHOU-B108和直链藻(Melosira sp.)SHOU-B110.采用单因子实验方法,研究了不同温度、光照强度和盐度对3株硅藻生长的影响,并分析了适宜温度、光照强度和盐度条件下3株硅藻的细胞组成.结果表明:角毛藻SHOU-B98、小环藻SHOU-B108和直链藻SHOU-B110的最适生长温度分别为22.3、20.6和24.7℃;最适光照强度分别为28.0、40.2和69.8 μmol· m-2 ·s-1;最适盐度分别为12.6、6.1和6.7.在适宜培养条件下,角毛藻SHOU-B98、小环藻SHOU-B108和直链藻SHOU-B110的蛋白质含量(占干重)分别为25.88%、21.01%和18.81%;总脂含量分别为10.36%、8.35%和11.34%.小环藻SHOU-B108含有丰富的20∶5n-3(EPA,19.13%)和20∶4n-6(ARA,13.47%).角毛藻SHOU-B98和直链藻SHOU-B110分别含有3.43%和5.90%的22∶ 6n-3(DHA).此3种硅藻富含多不饱和脂肪酸,并且对低盐度有一定的适应性,可作为河口地区特种经济水产动物幼体的饵料微藻.

  20. Conceptualization of sustainable boreal forests development in present-day economics.

    OpenAIRE

    Zhideleva, Valentina

    2014-01-01

    In research of boreal forests conservation and sustainable development mechanism in the climate changes conditions the main aspect is a study of various natural forces and the society, interests of different segments of population, conditions and productivity of forest ecosystems, threats removal dealing with growing of new forest making tree species and spruce stands drying and their interference. To achieve and protect sustainable development of boreal forests there is a need to arrange mon...

  1. Effects of Different Planting Patterns on Cotton Yield and Soil Water-salt under Brackish Water Irrigation before Sowing%微咸水造墒条件下植棉方式对产量与土壤水盐的影响

    Institute of Scientific and Technical Information of China (English)

    张俊鹏; 曹彩云; 冯棣; 孙景生; 李科江; 刘浩

    2013-01-01

    Effects of six planting patterns on cotton soil water-salt movement, seedling rate, leaf area index, yield and fiber quality under irrigation before sowing with 5 g/L brackish water were studied by plot comparative trial. The planting patterns were respectively seeding raising and soil-substrate transplanting with plastic mulching, seeding raising in sand and root-naked transplanting with plastic mulching, seeding raising and soil-substrate transplanting without plastic mulching, seeding raising in sand and root-naked transplanting without plastic mulching, and bunch planting without plastic mulching. The results showed that salt stress towards cotton was reduced by applying plastic film mulching to decrease soil evaporation, improve soil temperature as well as inhibit salt accumulation in surface. Under the film mulching conditions, the cotton seedling rate, leaf area index before blossoming and boll forming stage, pre-frost yield and yield were higher than that without plastic mulching. Fiber quality was also improved. The techniques of seeding raising and soil-substrate transplanting and seeding raising in sand and root-naked transplanting showed a good yield-increasing potential. Especially during the successive overcast days in the middle-late stages of cotton (in 2011 ) , the yield of seedling transplantation cotton was greatly improved.%采用小区对比试验,研究了5g/L微咸水造墒条件下不同种植方式(基质育苗移栽覆膜、沙培育苗移栽覆膜、点播覆膜与基质育苗移栽不覆膜、沙培育苗移栽不覆膜、点播不覆膜)对棉花土壤水盐变化过程、成苗率、叶面积指数、产量以及纤维品质的影响.结果表明,地膜覆盖通过减少土壤蒸发、提高土壤温度和抑制盐分表聚,削弱了盐分胁迫对棉花的危害程度,棉花的成苗率、花铃期前的叶面积指数、霜前花率以及产量均高于无覆盖处理,同时有效地提高了棉花的纤维品质;基质育苗移栽

  2. Russian boreal peatlands dominate the natural European methane budget

    International Nuclear Information System (INIS)

    About 60% of the European wetlands are located in the European part of Russia. Nevertheless, data on methane emissions from wetlands of that area are absent. Here we present results of methane emission measurements for two climatically different years from a boreal peatland complex in European Russia. Winter fluxes were well within the range of what has been reported for the peatlands of other boreal regions before, but summer fluxes greatly exceeded the average range of 5–80 mg CH4 m−2 d−1 for the circumpolar boreal zone. Half of the measured fluxes ranged between 150 and 450 mg CH4 m−2 d−1. Extrapolation of our data to the whole boreal zone of European Russia shows that theses emissions could amount to up to 2.7 ± 1.1 Tg CH4 a−1, corresponding to 69% of the annual emissions from European wetlands or 33% of the total annual natural European methane emission. In 2008, climatic conditions corresponded to the long term mean, whereas the summer of 2011 was warmer and noticeably drier. Counterintuitively, these conditions led to even higher CH4 emissions, with peaks up to two times higher than the values measured in 2008. As Russian peatlands dominate the areal extend of wetlands in Europe and are characterized by very high methane fluxes to the atmosphere, it is evident, that sound European methane budgeting will only be achieved with more insight into Russian peatlands. (letter)

  3. Russian boreal peatlands dominate the natural European methane budget

    Science.gov (United States)

    Schneider, Julia; Jungkunst, Hermann F.; Wolf, Ulrike; Schreiber, Peter; Gažovič, Michal; Miglovets, Mikhail; Mikhaylov, Oleg; Grunwald, Dennis; Erasmi, Stefan; Wilmking, Martin; Kutzbach, Lars

    2016-01-01

    About 60% of the European wetlands are located in the European part of Russia. Nevertheless, data on methane emissions from wetlands of that area are absent. Here we present results of methane emission measurements for two climatically different years from a boreal peatland complex in European Russia. Winter fluxes were well within the range of what has been reported for the peatlands of other boreal regions before, but summer fluxes greatly exceeded the average range of 5-80 mg CH4 m-2 d-1 for the circumpolar boreal zone. Half of the measured fluxes ranged between 150 and 450 mg CH4 m-2 d-1. Extrapolation of our data to the whole boreal zone of European Russia shows that theses emissions could amount to up to 2.7 ± 1.1 Tg CH4 a-1, corresponding to 69% of the annual emissions from European wetlands or 33% of the total annual natural European methane emission. In 2008, climatic conditions corresponded to the long term mean, whereas the summer of 2011 was warmer and noticeably drier. Counterintuitively, these conditions led to even higher CH4 emissions, with peaks up to two times higher than the values measured in 2008. As Russian peatlands dominate the areal extend of wetlands in Europe and are characterized by very high methane fluxes to the atmosphere, it is evident, that sound European methane budgeting will only be achieved with more insight into Russian peatlands.

  4. Decreases in Soil Moisture and Organic Matter Quality Suppress Microbial Decomposition Following a Boreal Forest Fire

    Energy Technology Data Exchange (ETDEWEB)

    Holden, Sandra R.; Berhe, Asmeret A.; Treseder, Kathleen K.

    2015-08-01

    Climate warming is projected to increase the frequency and severity of wildfires in boreal forests, and increased wildfire activity may alter the large soil carbon (C) stocks in boreal forests. Changes in boreal soil C stocks that result from increased wildfire activity will be regulated in part by the response of microbial decomposition to fire, but post-fire changes in microbial decomposition are poorly understood. Here, we investigate the response of microbial decomposition to a boreal forest fire in interior Alaska and test the mechanisms that control post-fire changes in microbial decomposition. We used a reciprocal transplant between a recently burned boreal forest stand and a late successional boreal forest stand to test how post-fire changes in abiotic conditions, soil organic matter (SOM) composition, and soil microbial communities influence microbial decomposition. We found that SOM decomposing at the burned site lost 30.9% less mass over two years than SOM decomposing at the unburned site, indicating that post-fire changes in abiotic conditions suppress microbial decomposition. Our results suggest that moisture availability is one abiotic factor that constrains microbial decomposition in recently burned forests. In addition, we observed that burned SOM decomposed more slowly than unburned SOM, but the exact nature of SOM changes in the recently burned stand are unclear. Finally, we found no evidence that post-fire changes in soil microbial community composition significantly affect decomposition. Taken together, our study has demonstrated that boreal forest fires can suppress microbial decomposition due to post-fire changes in abiotic factors and the composition of SOM. Models that predict the consequences of increased wildfires for C storage in boreal forests may increase their predictive power by incorporating the observed negative response of microbial decomposition to boreal wildfires.

  5. Reserve selection in boreal forest

    OpenAIRE

    Lundström, Johanna

    2013-01-01

    Most boreal forests in North Europe are intensively managed, and the forest landscape is far from its natural stage leading to hundreds of species being threatened in Sweden alone. Reserves are established to protect biodiversity, but since the resources available for conservation do not cover all species in need of protection, effective prioritization is essential. In this thesis, a reserve selection model based on a goal programming approach was developed, finding the optimal age comp...

  6. Predictability of Zonal Means During Boreal Summer

    Science.gov (United States)

    Schubert, Siegfried; Suarez, Max J.; Pegion, Philip J.; Kistler, Michael A.; Kumar, Arun; Einaudi, Franco (Technical Monitor)

    2001-01-01

    This study examines the predictability of seasonal means during boreal summer. The results are based on ensembles of June-July-August (JJA) simulations (started in mid May) carried out with the NASA Seasonal-to-Interannual Prediction Project (NSIPP-1) atmospheric general circulation model (AGCM) forced with observed sea surface temperatures (SSTS) and sea ice for the years 1980-1999. We find that the predictability of the JJA extra-tropical height field is primarily in the zonal mean component of the response to the SST anomalies. This contrasts with the cold season (January-February-March) when the predictability of seasonal means in the boreal extratropics is primarily in the wave component of the El Nino/Southern Oscillation (ENSO) response. Two patterns dominate the interannual variability of the ensemble mean JJA zonal mean height field. One has maximum variance in the tropical/subtropical upper troposphere, while the other has substantial variance in middle latitudes of both hemispheres. Both are symmetric with respect to the equator. A regression analysis suggests that the tropical/subtropical pattern is associated with SST anomalies in the far eastern tropical Pacific and the Indian Ocean, while the middle latitude pattern is forced by SST anomalies in the tropical Pacific just east of the dateline. The two leading zonal height patterns are reproduced in model runs forced with the two leading JJA SST patterns of variability. A comparison with observations shows a signature of the middle latitude pattern that is consistent with the occurrence of dry and wet summers over the United States. We hypothesize that both patterns, while imposing only weak constraints on extratropical warm season continental-scale climates, may play a role in the predilection for drought or pluvial conditions.

  7. Modeling physical and biogeochemical controls over carbon accumulation in a boreal forest soil

    Science.gov (United States)

    Carrasco, J.J.; Neff, J.C.; Harden, J.W.

    2006-01-01

    Boreal soils are important to the global C cycle owing to large C stocks, repeated disturbance from fire, and the potential for permafrost thaw to expose previously stable, buried C. To evaluate the primary mechanisms responsible for both short- and long-term C accumulation in boreal soils, we developed a multi-isotope (12,14C) Soil C model with dynamic soil layers that develop through time as soil organic matter burns and reaccumulates. We then evaluated the mechanisms that control organic matter turnover in boreal regions including carbon input rates, substrate recalcitrance, soil moisture and temperature, and the presence of historical permafrost to assess the importance of these factors in boreal C accumulation. Results indicate that total C accumulation is controlled by the rate of carbon input, decomposition rates, and the presence of historical permafrost. However, unlike more temperate ecosystems, one of the key mechanisms involved in C preservation in boreal soils examined here is the cooling of subsurface soil layers as soil depth increases rather than increasing recalcitrance in subsurface soils. The propagation of the 14C bomb spike into soils also illustrates the importance of historical permafrost and twentieth century warming in contemporary boreal soil respiration fluxes. Both 14C and total C simulation data also strongly suggest that boreal SOM need not be recalcitrant to accumulate; the strong role of soil temperature controls on boreal C accumulation at our modeling test site in Manitoba, Canada, indicates that carbon in the deep organic soil horizons is probably relatively labile and thus subject to perturbations that result from changing climatic conditions in the future. Copyright 2006 by the American Geophysical Union.

  8. Bioaccumulation of microcystins in invasive bivalves: A case study from the boreal lagoon ecosystem

    Directory of Open Access Journals (Sweden)

    Aistė Paldavičienė

    2015-01-01

    Full Text Available In the current study we present the first report on the bioaccumulation of microcystins (MC in zebra mussel Dreissena polymorpha from the eutrophic brackish water Curonian Lagoon. The bioaccumulation capacity was related to age structure of mussels and ambient environmental conditions. We also discuss the relevant implications of these findings for biomonitoring of toxic cyanobacteria blooms in the Curonian Lagoon and potential consequences for D. polymorpha cultivation activities considered for the futures as remediation measure. Samples for the analysis were collected twice per year, in June and September, in 2006, 2007 and 2008, from two sites within the littoral zone of the lagoon. The highest microcystin concentrations were measured in mussels larger than 30 mm length and sampled in 2006 (when a severe toxic cyanobacteria bloom occurred. In the following years, a consistent reduction in bioaccumulated MC concentration was noticed. However, certain amount of microcystin was recorded in mussel tissues in 2007 and 2008, when no cyanotoxins were reported in the phytoplankton. Considering high depuration rates and presence of cyanotoxins in the bottom sediments well after the recorded toxic blooms, we assume mechanism of secondary contamination when microcystin residuals could be uptaken by mussels with resuspended sediment particles.

  9. Effects of boreal forest vegetation on global climate

    Science.gov (United States)

    Bonan, Gordon B.; Pollard, David; Thompson, Starley L.

    1992-10-01

    TERRESTRIAL ecosystems are thought to play an important role in determining regional and global climate1-6 one example of this is in Amazonia, where destruction of the tropical rainforest leads to warmer and drier conditions4-6. Boreal forest ecosystems may also affect climate. As temperatures rise, the amount of continental and oceanic snow and ice is reduced, so the land and ocean surfaces absorb greater amounts of solar radiation, reinforcing the warming in a 'snow/ice/albedo' feedback which results in large climate sensitivity to radiative forcings7-9. This sensitivity is moderated, however, by the presence of trees in northern latitudes, which mask the high reflectance of snow10,11, leading to warmer winter temperatures than if trees were not present12-14. Here we present results from a global climate model which show that the boreal forest warms both winter and summer air temperatures, relative to simulations in which the forest is replaced with bare ground or tundra vegetation. Our results suggest that future redistributions of boreal forest and tundra vegetation (due, for example, to extensive logging, or the influence of global warming) could initiate important climate feedbacks, which could also extend to lower latitudes.

  10. Ecosystem Responses to Partial Harvesting in Eastern Boreal Mixedwood Stands

    Directory of Open Access Journals (Sweden)

    Brian D. Harvey

    2013-05-01

    Full Text Available Partial harvesting has been proposed as a key aspect to implementing ecosystem management in the Canadian boreal forest. We report on a replicated experiment located in boreal mixedwoods of Northwestern Quebec. In the winter of 2000–2001, two partial harvesting treatments, one using a dispersed pattern, and a second, which created a (400 m2 gap pattern, were applied to a 90-year-old aspen-dominated mixed stand. The design also included a clear cut and a control. Over the course of the following eight years, live tree, coarse woody debris, regeneration and ground beetles were inventoried at variable intervals. Our results indicate that all harvesting treatments created conditions favorable to balsam fir (Abies balsamea sapling growth and trembling aspen (Populus tremuloides sapling recruitment. However, balsam fir and trembling aspen regeneration and ground beetles response to gap cuts were closer to patterns observed in clear cuts than in dispersed harvesting. The underlying reasons for these differing patterns can be linked to factors associated with the contrasting light regimes created by the two partial harvesting treatments. The study confirms that partially harvesting is an ecologically sound approach in boreal mixedwoods and could contribute to maintaining the distribution of stand ages at the landscape level.

  11. Methane oxidation: isotopic enrichment factors in freshwater boreal reservoirs

    International Nuclear Information System (INIS)

    Methane oxidation plays a vital role in controlling the flux of CH4 from many ecosystems. Release of the green house gas CH4 to the atmosphere during creation and operation of hydroelectric reservoirs is of concern because of the dramatic changes in C and nutrient cycling that result from flooding. Experimentally flooded reservoirs in the boreal forest at the Experimental Lakes Area, northwestern Ontario, Canada, have been under study for a decade. In these large-scale ecosystem experiments, stable C isotopic ratios are used to determine the importance of CH4 oxidation but quantification requires knowledge of the C isotope enrichment factor associated with CH4 oxidation under the appropriate environmental conditions. Laboratory incubations were used to assess the CH4 oxidation enrichment factors in 3 experimental boreal reservoirs with different soil and vegetation, and flood histories. As a result of flooding, new flooded surfaces were created with different temperature and hydrologic regimes and the importance of CH4 oxidation in controlling the flux of CH4 to the atmosphere changed significantly. However, isotopic ratio data from different systems could not be compared directly because the enrichment factor changed between systems. The enrichment factor in a flooded boreal wetland ecosystem (ELARP) decreased with temperature and the rate of CH4 oxidation increased with temperature. This was in contrast with two flooded upland boreal forest reservoirs (Flooded Upland Dynamics Experiment) where the enrichment factor was smaller than in ELARP and there was little or no temperature effect on the enrichment factors or rates of CH4 oxidation

  12. Sustaining Aquatic Ecosystems in Boreal Regions

    Directory of Open Access Journals (Sweden)

    David Schindler

    1998-12-01

    Full Text Available Few boreal waters are managed in a sustainable manner, because cumulative effects of a variety of human activities are not considered. Fisheries and water quality have declined in most large water bodies of the southern boreal zone. Some of the reasons are direct, including overexploitation of fisheries, alteration of flow patterns, introductions of non-native species, and discharge of eutrophying nutrients and persistent contaminants. However, improper management of watersheds and airsheds also causes degradation of aquatic ecosystems. Clear-cut logging, climatic warming, acid precipitation, and stratospheric ozone depletion are among the more important of these indirect stressors. There are important interactions among these stressors, requiring that they not be treated in isolation. Ecological sustainability of boreal waters would require that exploitation of all parts of the boreal landscape be much lower than it is at present. Unfortunately, management for sustainability is lagging far behind scientific understanding in most countries.

  13. Ozone photochemistry in boreal biomass burning plumes

    OpenAIRE

    M. Parrington; Palmer, P. I.; Lewis, A. C.; J. D. Lee; A. R. Rickard; De Carlo, P; Taylor, J.W.; J. R. Hopkins; S. Punjabi; D. E. Oram; G. Forster; Aruffo, E.; Moller, S. J.; Bauguitte, S. J.-B.; Allan, J. D.

    2013-01-01

    We present an analysis of ozone (O3) photochemistry observed by aircraft measurements of boreal biomass burning plumes over eastern Canada in the summer of 2011. Measurements of O3 and a number of key chemical species associated with O3 photochemistry, including non-methane hydrocarbons (NMHCs), nitrogen oxides (NOx) and total nitrogen containing species (NOy), were made from the UK FAAM BAe-146 research aircraft as part of the "quantifying the impact of BOReal forest fires on Tropospheric ox...

  14. Ozone photochemistry in boreal biomass burning plumes

    OpenAIRE

    M. Parrington; Palmer, P. I.; Lewis, A. C.; J. D. Lee; A. R. Rickard; P. Di Carlo; Taylor, J.W.; J. R. Hopkins; S. Punjabi; D. E. Oram; G. Forster; Aruffo, E.; Moller, S. J.; Bauguitte, S. J.-B.; Allan, J. D.

    2013-01-01

    We present an analysis of ozone photochemistry observed by aircraft measurements of boreal biomass burning plumes over Eastern Canada in the summer of 2011. Measurements of ozone and a number of key chemical species associated with ozone photochemistry, including non-methane hydrocarbons (NMHCs), nitrogen oxides (NOx) and total nitrogen containing species (NOy), were made from the UK FAAM BAe-146 research aircraft as part of the quantifying the impact of BOReal forest fires on tropospheric ox...

  15. Methane oxidation in a boreal climate in an experimental landfill cover composed from mechanically-biologically treated waste.

    Science.gov (United States)

    Einola, J-K M; Sormunen, K M; Rintala, J A

    2008-12-15

    The present study evaluated microbial methane (CH4) oxidation in a boreally located outdoor landfill lysimeter (volume 112 m3, height 3.9 m) filled with mechanically-biologically treated waste (MBT residual) and containing a cover layer made from the same MBT residual. The calculations based on gas emission and pore gas measurements showed that, between April and October 2005, a significant proportion (> 96%) of the methane produced (landfill covers in field conditions in a boreal climate. PMID:18823644

  16. Carbon in boreal coniferous forest soil

    Energy Technology Data Exchange (ETDEWEB)

    Westman, C.J.; Ilvesniemi, H.; Liski, J.; Mecke, M. [Helsinki Univ. (Finland). Dept. of Forest Ecology; Fritze, H.; Helmisaari, H.S.; Pietikaeinen, J.; Smolander, A. [Finnish Forest Research Inst., Vantaa (Finland)

    1996-12-31

    The working hypothesis of the research was that the soil of boreal forests is a large carbon store and the amount of C is still increasing in young soils, like in the forest soils of Finland, which makes these soils important sinks for atmospheric CO{sub 2}. Since the processes defining the soil C balance, primary production of plants and decomposition, are dependent on environmental factors and site properties, it was assumed that the organic carbon pool in the soil is also dependent on the same factors. The soil C store is therefore likely to change in response to climatic warming. The aim of this research was to estimate the C balance of forest soil in Finland and predict changes in the balance in response to changes in climatic conditions. To achieve the aim (1) intensive empirical experimentation on the density of C in different pools in the soil and on fluxes between the pools was done was done, (2) the effect of site fertility and climate on the amount and properties of organic C in forest soil was investigated and (3) dynamic modelling for investigating dynamics of the soil C storage was used

  17. The Elusive Boreal Forest Thaumarchaeota

    Directory of Open Access Journals (Sweden)

    Malin Bomberg

    2016-06-01

    Full Text Available In recent years, Archaea have, with increasing frequency, been found to colonize both agricultural and forest soils in temperate and boreal regions. The as yet uncultured group I.1c of the Thaumarchaeota has been of special interest. These Archaea are widely distributed in mature vegetated acidic soils, but little has been revealed of their physiological and biological characteristics. The I.1c Thaumarchaeota have been recognized as a microbial group influenced by plant roots and mycorrhizal fungi, but appear to have distinct features from their more common soil dwelling counterparts, such as the Nitrosotalea or Nitrososphaera. They appear to be highly dependent on soil pH, thriving in undisturbed vegetated soils with a pH of 5 or below. Research indicate that these Archaea require organic carbon and nitrogen sources for growth and that they may live both aerobically and anaerobically. Nevertheless, pure cultures of these microorganisms have not yet been obtained. This review will focus on what is known to date about the uncultured group I.1c Thaumarchaeota formerly known as the “Finnish Forest Soil” (FFS Archaea.

  18. Investigations of the environmental conditions in Glomfjord and Holandsfjord in 1991-92. Part 2. Model simulation of the impact of changed fresh water supply to Holandsfjord; Undersoekelser av miljoeforhold i Glomfjord og Holandsfjord i 1991-92. Delrapport 2. Modellsimulering av effekter av endret ferskvannstilfoersel til Holandsfjord

    Energy Technology Data Exchange (ETDEWEB)

    Stigebrandt, A.; Molvaer, J.

    1994-12-31

    The development of Svartisen hydroelectric power station at the head of the Holandsfjord, Norway, will almost triple the annual fresh water supply to the fjord. This report describes a mathematical model which simulates the effects of changing the supply of fresh water and of particulate material to the inner and outer parts of the fjord. The model has been used to simulate five different combinations of these two variables. The water discharged from the power station increases the thickness of the brackish water layer, especially in winter. This increases the risk of ice formation. The concentration of phytoplankton above and below the brackish water layer will increase somewhat. The change in light absorption with depth will be relatively small, but also depend on how the supply of particulate material increases or decreases for the two parts of the fjord. The deep water oxygen conditions remain good after the hydro power regulation. 21 refs., 25 refs., 9 tabs.

  19. Disturbance Regimes and Landscape Heterogeneity in the Boreal Forest

    OpenAIRE

    Lyons, Evan Albert

    2015-01-01

    The boreal forest circles the high northern latitudes but it is far from a continuous carpet of evergreen trees. Rather, the boreal forest is a patchwork of land cover types in constant flux as they recover from wildfire and then are burned again. This fast turnover of land cover makes the boreal forest particularly susceptible to rapid change in response to climate. Furthermore, the boreal forest is an important component of the climate system that pumps heat into the atmosphere and signi...

  20. Main dynamics and drivers of boreal forests fire regimes during the Holocene

    Science.gov (United States)

    Molinari, Chiara; Lehsten, Veiko; Blarquez, Olivier; Clear, Jennifer; Carcaillet, Christopher; Bradshaw, Richard HW

    2015-04-01

    Forest fire is one of the most critical ecosystem processes in the boreal megabiome, and it is likely that its frequency, size and severity have had a primary role in vegetation dynamics since the Last Ice Age (Kasischke & Stocks 2000). Fire not only organizes the physical and biological attributes of boreal forests, but also affects biogeochemical cycling, particularly the carbon balance (Balshi et al. 2007). Due to their location at climatically sensitive northern latitudes, boreal forests are likely to be significantly affected by global warming with a consequent increase in biomass burning (Soja et al. 2007), a variation in vegetation structure and composition (Johnstone et al. 2004) and a rise in atmospheric carbon dioxide concentration (Bond-Lamberty et al. 2007). Even if the ecological role of wildfire in boreal forest is widely recognized, a clearer understanding of the environmental factors controlling fire dynamics and how variations in fire regimes impact forest ecosystems is essential in order to place modern fire processes in a meaningful context for projecting ecosystem behaviour in a changing environment (Kelly et al. 2013). Because fire return intervals and successional cycles in boreal forests occur over decadal to centennial timescales (Hu et al. 2006), palaeoecological research seems to be one of the most promising tool for elucidating ecosystem changes over a broad range of environmental conditions and temporal scales. Within this context, our first aim is to reconstruct spatial and temporal patterns of boreal forests fire dynamics during the Holocene based on sedimentary charcoal records. As a second step, trends in biomass burning will be statistically analysed in order to disentangle between regional and local drivers. The use of European and north-American sites will give us the unique possibility to perform a large scale analysis on one of the broadest biome in the world and to underline the different patterns of fire in these two

  1. Aspects of the biodiversity of brackish water foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Jayalakshmy, K.V.; Rao, K.K.

    of species are very valuable, despite giving only very little insight into the highly important biotic constraints of the dynamic processes that establish the real niches of animals. Lee (1974) attempted to quantify the biotic and abiotic parameters for some... that take into account the joint absences are not robust enough to be generally applicable (Field et al., 1982). There- fore the measure used by Bray and Curtis (1957) (Clifford and Stephenson, 1975) has been applied here since it is not affected by joint...

  2. Evaluation of Modern Irrigation Techniques with Brackish Water

    OpenAIRE

    Aboulila, Tarek Selim

    2012-01-01

    Modern irrigation techniques are becoming increasingly important in water-scarce countries especially in arid and semiarid regions. Higher crop production and better water use efficiency are usually achieved by drip irrigation as compared to other irrigation methods. Furthermore, by using drip irrigation simultaneously with brackish irrigation water, some of the water stress due to shortage of fresh water resources can be managed. The objective of the current study was to investigate the infl...

  3. Desalination of brackish waters by electrodialysis. I. Process variable studies

    International Nuclear Information System (INIS)

    This study was carried out with solutions of 5000, 3000 and 1000 ppm of NaCl, and 3000 and 1000 ppm of NaSO4. A stack-pack of 20 pairs membranes, Nepton lonics 61 AZL 183 -cationic- and 111 BZL 183 -anionic- with 220 cm2/membrane was used. For the above mentioned Solutions the following values were determined: Limiting current density; the values of n and K in the expression which relates the L.C.D. with flow rate; dependence of spent energy on flow rate; spent energy and time of operation versus initial current and concentration of the solution, and finally the influence of the concentration potential on the electrodialytic process. A discussion of the results obtained is included. (Author) 18 refs

  4. DNA barcoding identifies Argentine fishes from marine and brackish waters.

    Directory of Open Access Journals (Sweden)

    Ezequiel Mabragaña

    Full Text Available BACKGROUND: DNA barcoding has been advanced as a promising tool to aid species identification and discovery through the use of short, standardized gene targets. Despite extensive taxonomic studies, for a variety of reasons the identification of fishes can be problematic, even for experts. DNA barcoding is proving to be a useful tool in this context. However, its broad application is impeded by the need to construct a comprehensive reference sequence library for all fish species. Here, we make a regional contribution to this grand challenge by calibrating the species discrimination efficiency of barcoding among 125 Argentine fish species, representing nearly one third of the known fauna, and examine the utility of these data to address several key taxonomic uncertainties pertaining to species in this region. METHODOLOGY/PRINCIPAL FINDINGS: Specimens were collected and morphologically identified during crusies conducted between 2005 and 2008. The standard BARCODE fragment of COI was amplified and bi-directionally sequenced from 577 specimens (mean of 5 specimens/species, and all specimens and sequence data were archived and interrogated using analytical tools available on the Barcode of Life Data System (BOLD; www.barcodinglife.org. Nearly all species exhibited discrete clusters of closely related haplogroups which permitted the discrimination of 95% of the species (i.e. 119/125 examined while cases of shared haplotypes were detected among just three species-pairs. Notably, barcoding aided the identification of a new species of skate, Dipturus argentinensis, permitted the recognition of Genypterus brasiliensis as a valid species and questions the generic assignment of Paralichthys isosceles. CONCLUSIONS/SIGNIFICANCE: This study constitutes a significant contribution to the global barcode reference sequence library for fishes and demonstrates the utility of barcoding for regional species identification. As an independent assessment of alpha taxonomy, barcodes provide robust support for most morphologically based taxon concepts and also highlight key areas of taxonomic uncertainty worthy of reappraisal.

  5. Role of mangroves in brackish water fish culture

    Digital Repository Service at National Institute of Oceanography (India)

    Wafar, S.

    Mangroves is a specialized marine ecosystem consisting of a group of plants growing in muddy, loose and wet soils in tropical and subtropical areas, comprising of shallow, coastal waters, deltas, estuaries or lagoons. Besides ecological importance...

  6. DNA Barcoding Identifies Argentine Fishes from Marine and Brackish Waters

    Science.gov (United States)

    Mabragaña, Ezequiel; Díaz de Astarloa, Juan Martín; Hanner, Robert; Zhang, Junbin; González Castro, Mariano

    2011-01-01

    Background DNA barcoding has been advanced as a promising tool to aid species identification and discovery through the use of short, standardized gene targets. Despite extensive taxonomic studies, for a variety of reasons the identification of fishes can be problematic, even for experts. DNA barcoding is proving to be a useful tool in this context. However, its broad application is impeded by the need to construct a comprehensive reference sequence library for all fish species. Here, we make a regional contribution to this grand challenge by calibrating the species discrimination efficiency of barcoding among 125 Argentine fish species, representing nearly one third of the known fauna, and examine the utility of these data to address several key taxonomic uncertainties pertaining to species in this region. Methodology/Principal Findings Specimens were collected and morphologically identified during crusies conducted between 2005 and 2008. The standard BARCODE fragment of COI was amplified and bi-directionally sequenced from 577 specimens (mean of 5 specimens/species), and all specimens and sequence data were archived and interrogated using analytical tools available on the Barcode of Life Data System (BOLD; www.barcodinglife.org). Nearly all species exhibited discrete clusters of closely related haplogroups which permitted the discrimination of 95% of the species (i.e. 119/125) examined while cases of shared haplotypes were detected among just three species-pairs. Notably, barcoding aided the identification of a new species of skate, Dipturus argentinensis, permitted the recognition of Genypterus brasiliensis as a valid species and questions the generic assignment of Paralichthys isosceles. Conclusions/Significance This study constitutes a significant contribution to the global barcode reference sequence library for fishes and demonstrates the utility of barcoding for regional species identification. As an independent assessment of alpha taxonomy, barcodes provide robust support for most morphologically based taxon concepts and also highlight key areas of taxonomic uncertainty worthy of reappraisal. PMID:22174860

  7. Desalination of Saline and Brackish Waters using Carbon Aerogel Technology

    OpenAIRE

    Mohammad Reza Massoudinejad; Hamed Mohammadi; Akbar Eslami; Hossein Najafi; Behzad Rezayi fard; Gholam Hossein Joshani

    2012-01-01

    Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 Background and Objectives: The increasing demand for drinking water has led scientists to the use of saline waters, but existing desalinating processes are very expensive. carbon aerogel is a type of organic aerogel that is suitable for desalination owing to its unique porous structure. Low potential of fouling and deposits, very low wastewater production, ele...

  8. Browning boreal forests of western North America

    Science.gov (United States)

    Verbyla, David

    2011-12-01

    The GIMMS NDVI dataset has been widely used to document a 'browning trend' in North American boreal forests (Goetz et al 2005, Bunn et al 2007, Beck and Goetz 2011). However, there has been speculation (Alcaraz-Segura et al 2010) that this trend may be an artifact due to processing algorithms rather than an actual decline in vegetation activity. This conclusion was based primarily on the fact that GIMMS NDVI did not capture NDVI recovery within most burned areas in boreal Canada, while another dataset consistently showed post-fire increasing NDVI. I believe that the results of Alcaraz-Segura et al (2010) were due simply to different pixel sizes of the two datasets (64 km2 versus 1 km2 pixels). Similar results have been obtained from tundra areas greening in Alaska, with the results simply due to these pixel size differences (Stow et al 2007). Furthermore, recent studies have documented boreal browning trends based on NDVI from other sensors. Beck and Goetz (2011) have shown the boreal browning trend derived from a different sensor (MODIS) to be very similar to the boreal browning trend derived from the GIMMS NDVI dataset for the circumpolar boreal region. Parent and Verbyla (2010) found similar declining NDVI patterns based on NDVI from Landsat sensors and GIMMS NDVI in boreal Alaska. Zhang et al (2008) found a similar 'browning trend' in boreal North America based on a production efficiency model using an integrated AVHRR and MODIS dataset. The declining NDVI trend in areas of boreal North America is consistent with tree-ring studies (D'Arrigo et al 2004, McGuire et al 2010, Beck et al 2011). The decline in tree growth may be due to temperature-induced drought stress (Barber et al 2000) caused by higher evaporative demands in a warming climate (Lloyd and Fastie 2002). In a circumpolar boreal study, Lloyd and Bunn (2007) found that a negative relationship between temperature and tree-ring growth occurred more frequently in warmer parts of species' ranges

  9. Antioxidant Potential of Bark Extracts from Boreal Forest Conifers.

    Science.gov (United States)

    Legault, Jean; Girard-Lalancette, Karl; Dufour, Dominic; Pichette, André

    2013-01-01

    The bark of boreal forest conifers has been traditionally used by Native Americans to treat various ailments and diseases. Some of these diseases involve reactive oxygen species (ROS) that can be prevented by the consumption of antioxidants such as phenolic compounds that can be found in medicinal plants. In this study, ultrasonic assisted extraction has been performed under various solvent conditions (water:ethanol mixtures) on the bark of seven boreal forest conifers used by Native Americans including: Pinus strobus, Pinus resinosa, Pinus banksiana, Picea mariana, Picea glauca, Larix laricina, and Abies balsamea. The total phenolic content, as well as ORACFL potency and cellular antioxidant activity (IC50), were evaluated for all bark extracts, and compared with the standardized water extract of Pinus maritima bark (Pycnogenol), which showed clinical efficiency to prevent ROS deleterious effects. The best overall phenolic extraction yield and antioxidant potential was obtained with Picea glauca and Picea mariana. Interestingly, total phenolic content of these bark extracts was similar to Pycnogenol but their antioxidant activity were higher. Moreover, most of the extracts did not inhibit the growth of human skin fibroblasts, WS1. A significant correlation was found between the total phenolic content and the antioxidant activity for water extracts suggesting that these compounds are involved in the activity. PMID:26784337

  10. Antioxidant Potential of Bark Extracts from Boreal Forest Conifers

    Directory of Open Access Journals (Sweden)

    Jean Legault

    2013-07-01

    Full Text Available The bark of boreal forest conifers has been traditionally used by Native Americans to treat various ailments and diseases. Some of these diseases involve reactive oxygen species (ROS that can be prevented by the consumption of antioxidants such as phenolic compounds that can be found in medicinal plants. In this study, ultrasonic assisted extraction has been performed under various solvent conditions (water:ethanol mixtures on the bark of seven boreal forest conifers used by Native Americans including: Pinus strobus, Pinus resinosa, Pinus banksiana, Picea mariana, Picea glauca, Larix laricina, and Abies balsamea. The total phenolic content, as well as ORACFL potency and cellular antioxidant activity (IC50, were evaluated for all bark extracts, and compared with the standardized water extract of Pinus maritima bark (Pycnogenol, which showed clinical efficiency to prevent ROS deleterious effects. The best overall phenolic extraction yield and antioxidant potential was obtained with Picea glauca and Picea mariana. Interestingly, total phenolic content of these bark extracts was similar to Pycnogenol but their antioxidant activity were higher. Moreover, most of the extracts did not inhibit the growth of human skin fibroblasts, WS1. A significant correlation was found between the total phenolic content and the antioxidant activity for water extracts suggesting that these compounds are involved in the activity.

  11. Does the temporal mismatch hypothesis match in boreal populations?

    Science.gov (United States)

    Vatka, Emma; Rytkönen, Seppo; Orell, Markku

    2014-10-01

    The temporal mismatch hypothesis suggests that fitness is related to the degree of temporal synchrony between the energetic needs of the offspring and their food supply. The hypothesis has been a basis in studying the influence of climate warming on nature. This study enhances the knowledge on prevalence of temporal mismatches and their consequences in boreal populations, and questions the role of the temporal mismatch hypothesis as the principal explanation for the evolution of timing of breeding. To test this, we examined if synchrony with caterpillar prey or timing of breeding per se better explains reproductive output in North European parid populations. We compared responses of temperate-origin species, the great tit (Parus major) and the blue tit (Cyanistes caeruleus), and a boreal species, the willow tit (Poecile montanus). We found that phenologies of caterpillars and great tits, but not of blue tits, have advanced during the past decades. Phenologies correlated with spring temperatures that may function as cues about the timing of the food peak for great and blue tits. The breeding of great and blue tits and their caterpillar food remained synchronous. Synchrony explained breeding success better than timing of breeding alone. However, the synchrony effect arose only in certain conditions, such as with high caterpillar abundances or high breeding densities. Breeding before good synchrony seems advantageous at high latitudes, especially in the willow tit. Thus, the temporal mismatch hypothesis appears insufficient in explaining the evolution of timing of breeding. PMID:25024104

  12. The impact of boreal autumn SST anomalies over the South Pacific on boreal winter precipitation over East Asia

    Science.gov (United States)

    Ao, Juan; Sun, Jianqi

    2016-05-01

    The possible mechanism behind the variability in the dipole pattern of boreal winter precipitation over East Asia is analyzed in this study. The results show that the SST anomalies (SSTAs) over the South Pacific Ocean (SPO) in boreal autumn are closely related to the variability in the dipole pattern of boreal winter precipitation over East Asia. The physical link between the boreal autumn SPO SSTAs and the boreal winter East Asian precipitation dipole pattern is shown to mainly be the seasonal persistence of the SPO SSTAs themselves. The seasonal persistence of the SPO SSTAs can memorize and transport the signal of the boreal autumn SSTAs to the following winter, and then stimulates a meridional teleconnection pattern from the SH to the NH, resulting in a meridional dipole pattern of atmospheric circulation over East Asia in boreal winter. As a major influencing factor, this dipole pattern of the atmospheric circulation can finally lead to the anomalous precipitation dipole pattern over East Asia in boreal winter. These observed physical processes are further confirmed in this study through numerical simulation. The evidence from this study, showing the impact of the SPO SSTAs in boreal autumn, not only deepens our understanding of the variability in East Asian boreal winter precipitation, but also provides a potentially useful predictor for precipitation in the region.

  13. Carbonaceous aerosols from prescribed burning of a boreal forest ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Mazurek, M.A. (Brookhaven National Lab., Upton, NY (United States)); Cofer, W.R. III; Levine, J.S. (National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center)

    1990-10-01

    The identity and ambient mass concentrations of radiatively important carbonaceous aerosols were measured for a boreal forest prescribed burn conducted in northern Ontario, CAN in August 1989. Nonsize-segregated airborne particles were collected for smoldering-fire and full-fire conditions using a helicopter sampling platform. Total carbon (TC), organic carbon (OC) and elemental carbon (EC) were measured. Smoke plume mass concentrations of the OC and EC particles were greatest for full-fire conditions and had ranges of 1.560 to 2.160 mg/m{sup {minus}1} (OC) and 0.120 to 0.160 mg/m{sup {minus}3} (EC) with OC:EC ratios of 10 to 18, respectively. Smoldering fire conditions showed smoke plume OC and EC levels of 0.570--1.030 mg/m{sup {minus}3} (OC) and 0.006--0.050 mg/m{sup {minus}3} (EC) and much higher ratios of OC:EC (21 to 95). These aerosol data indicate the formation of EC particles is greatest during full-fire combustion of boreal forest material relative to smoldering combustion. However, EC particles comprise a minor fraction of the particulate carbon smoke aerosols for both full-fire and smoldering conditions; the major component of carbonaceous smoke aerosols emitted during the prescribed burn is OC. Overall, the OC and EC in-plume smoke aerosol data show nonuniform production of these particles during various stages of the prescribed burn, and major differences in the type of carbonaceous aerosol that is generated (OC versus EC).

  14. Carbonaceous aerosols from prescribed burning of a boreal forest ecosystem

    International Nuclear Information System (INIS)

    The identity and ambient mass concentrations of radiatively important carbonaceous aerosols were measured for a boreal forest prescribed burn conducted in northern Ontario, CAN in August 1989. Nonsize-segregated airborne particles were collected for smoldering-fire and full-fire conditions using a helicopter sampling platform. Total carbon (TC), organic carbon (OC) and elemental carbon (EC) were measured. Smoke plume mass concentrations of the OC and EC particles were greatest for full-fire conditions and had ranges of 1.560 to 2.160 mg/m-1 (OC) and 0.120 to 0.160 mg/m-3 (EC) with OC:EC ratios of 10 to 18, respectively. Smoldering fire conditions showed smoke plume OC and EC levels of 0.570--1.030 mg/m-3 (OC) and 0.006--0.050 mg/m-3 (EC) and much higher ratios of OC:EC (21 to 95). These aerosol data indicate the formation of EC particles is greatest during full-fire combustion of boreal forest material relative to smoldering combustion. However, EC particles comprise a minor fraction of the particulate carbon smoke aerosols for both full-fire and smoldering conditions; the major component of carbonaceous smoke aerosols emitted during the prescribed burn is OC. Overall, the OC and EC in-plume smoke aerosol data show nonuniform production of these particles during various stages of the prescribed burn, and major differences in the type of carbonaceous aerosol that is generated (OC versus EC)

  15. Influence of tree species on continental differences in boreal fires and climate feedbacks

    Science.gov (United States)

    Rogers, Brendan M.; Soja, Amber J.; Goulden, Michael L.; Randerson, James T.

    2015-03-01

    Wildfires are common in boreal forests around the globe and strongly influence ecosystem processes. However, North American forests support more high-intensity crown fires than Eurasia, where lower-intensity surface fires are common. These two types of fire can result in different net effects on climate as a consequence of their contrasting impacts on terrestrial albedo and carbon stocks. Here we use remote-sensing imagery, climate reanalysis data and forest inventories to evaluate differences in boreal fire dynamics between North America and Eurasia and their key drivers. Eurasian fires were less intense, destroyed less live vegetation, killed fewer trees and generated a smaller negative shortwave forcing. As fire weather conditions were similar across continents, we suggest that different fire dynamics between the two continents resulted from their dominant tree species. In particular, species that have evolved to spread and be consumed by crown fires as part of their life cycle dominate North American boreal forests. In contrast, tree species that have evolved to resist and suppress crown fires dominate Eurasian boreal forests. We conclude that species-level traits must be considered in global evaluations of the effects of fire on emissions and climate.

  16. Effects of disturbance and climate change on ecosystem performance in the Yukon River Basin boreal forest

    Science.gov (United States)

    Wylie, Bruce K.; Rigge, Matthew B.; Brisco, Brian; Mrnaghan, Kevin; Rover, Jennifer R.; Long, Jordan

    2014-01-01

    A warming climate influences boreal forest productivity, dynamics, and disturbance regimes. We used ecosystem models and 250 m satellite Normalized Difference Vegetation Index (NDVI) data averaged over the growing season (GSN) to model current, and estimate future, ecosystem performance. We modeled Expected Ecosystem Performance (EEP), or anticipated productivity, in undisturbed stands over the 2000–2008 period from a variety of abiotic data sources, using a rule-based piecewise regression tree. The EEP model was applied to a future climate ensemble A1B projection to quantify expected changes to mature boreal forest performance. Ecosystem Performance Anomalies (EPA), were identified as the residuals of the EEP and GSN relationship and represent performance departures from expected performance conditions. These performance data were used to monitor successional events following fire. Results suggested that maximum EPA occurs 30–40 years following fire, and deciduous stands generally have higher EPA than coniferous stands. Mean undisturbed EEP is projected to increase 5.6% by 2040 and 8.7% by 2070, suggesting an increased deciduous component in boreal forests. Our results contribute to the understanding of boreal forest successional dynamics and its response to climate change. This information enables informed decisions to prepare for, and adapt to, climate change in the Yukon River Basin forest.

  17. Climatic dipoles drive two principal modes of North American boreal bird irruption.

    Science.gov (United States)

    Strong, Courtenay; Zuckerberg, Benjamin; Betancourt, Julio L; Koenig, Walter D

    2015-05-26

    Pine Siskins exemplify normally boreal seed-eating birds that can be sparse or absent across entire regions of North America in one year and then appear in large numbers the next. These dramatic avian "irruptions" are thought to stem from intermittent but broadly synchronous seed production (masting) in one year and meager seed crops in the next. A prevalent hypothesis is that widespread masting in the boreal forest at high latitudes is driven primarily by favorable climate during the two to three consecutive years required to initiate and mature seed crops in most conifers. Seed production is expensive for trees and is much reduced in the years following masting, driving boreal birds to search elsewhere for food and overwintering habitat. Despite this plausible logic, prior efforts to discover climate-irruption relationships have been inconclusive. Here, analysis of more than 2 million Pine Siskin observations from Project FeederWatch, a citizen science program, reveals two principal irruption modes (North-South and West-East), both of which are correlated with climate variability. The North-South irruption mode is, in part, influenced by winter harshness, but the predominant climate drivers of both modes manifest in the warm season as continental-scale pairs of oppositely signed precipitation and temperature anomalies (i.e., dipoles). The climate dipoles juxtapose favorable and unfavorable conditions for seed production and wintering habitat, motivating a push-pull paradigm to explain irruptions of Pine Siskins and possibly other boreal bird populations in North America. PMID:25964328

  18. Palaeodata-informed modelling of large carbon losses from recent burning of boreal forests

    Science.gov (United States)

    Kelly, Ryan; Genet, Helene; McGuire, Anthony; Hu, Feng Sheng

    2016-01-01

    Wildfires play a key role in the boreal forest carbon cycle1, 2, and models suggest that accelerated burning will increase boreal C emissions in the coming century3. However, these predictions may be compromised because brief observational records provide limited constraints to model initial conditions4. We confronted this limitation by using palaeoenvironmental data to drive simulations of long-term C dynamics in the Alaskan boreal forest. Results show that fire was the dominant control on C cycling over the past millennium, with changes in fire frequency accounting for 84% of C stock variability. A recent rise in fire frequency inferred from the palaeorecord5 led to simulated C losses of 1.4 kg C m−2 (12% of ecosystem C stocks) from 1950 to 2006. In stark contrast, a small net C sink of 0.3 kg C m−2 occurred if the past fire regime was assumed to be similar to the modern regime, as is common in models of C dynamics. Although boreal fire regimes are heterogeneous, recent trends6 and future projections7 point to increasing fire activity in response to climate warming throughout the biome. Thus, predictions8 that terrestrial C sinks of northern high latitudes will mitigate rising atmospheric CO2 may be over-optimistic.

  19. Botany: Constraints to growth of boreal forests

    Science.gov (United States)

    Jarvis, Paul; Linder, Sune

    2000-06-01

    Understanding how the growth of trees at high latitudes in boreal forest is controlled is important for projections of global carbon sequestration and timber production in relation to climate change. Is stem growth of boreal forest trees constrained by the length of the growing season when stem cambial cells divide, or by the length of the period when resources can be captured? In both cases, the timing of the thaw in the spring is critical: neither cambial cell division nor uptake of nutrients and carbon dioxide can occur while the soil is frozen. Here we argue, on the basis of long-term observations made in northern Saskatchewan and Sweden, that the time between the spring thaw and the autumn freeze determines the amount of annual tree growth, mainly through temperature effects on carbon-dioxide uptake in spring and on nutrient availability and uptake during summer, rather than on cambial cell division.

  20. Explaining geographic gradients in winter selection of landscapes by boreal caribou with implications under global changes in Eastern Canada.

    Directory of Open Access Journals (Sweden)

    Julien Beguin

    Full Text Available Many animal species exhibit broad-scale latitudinal or longitudinal gradients in their response to biotic and abiotic components of their habitat. Although knowing the underlying mechanism of these patterns can be critical to the development of sound measures for the preservation or recovery of endangered species, few studies have yet identified which processes drive the existence of geographical gradients in habitat selection. Using extensive spatial data of broad latitudinal and longitudinal extent, we tested three hypotheses that could explain the presence of geographical gradients in landscape selection of the endangered boreal woodland caribou (Rangifer tarandus caribou during winter in Eastern Canadian boreal forests: 1 climate-driven selection, which postulates that geographic gradients are surrogates for climatic gradients; 2 road-driven selection, which proposes that boreal caribou adjust their selection for certain habitat classes as a function of proximity to roads; and 3 an additive effect of both roads and climate. Our data strongly supported road-driven selection over climate influences. Thus, direct human alteration of landscapes drives boreal caribou distribution and should likely remain so until the climate changes sufficiently from present conditions. Boreal caribou avoided logged areas two-fold more strongly than burnt areas. Limiting the spread of road networks and accounting for the uneven impact of logging compared to wildfire should therefore be integral parts of any habitat management plan and conservation measures within the range of the endangered boreal caribou. The use of hierarchical spatial models allowed us to explore the distribution of spatially-structured errors in our models, which in turn provided valuable insights for generating alternative hypotheses about processes responsible for boreal caribou distribution.

  1. Ozone photochemistry in boreal biomass burning plumes

    OpenAIRE

    M. Parrington; Palmer, P. I.; Lewis, A. C.; J. D. Lee; A. R. Rickard; P. Di Carlo; Taylor, J.W.; J. R. Hopkins; S. Punjabi; D. E. Oram; G. Forster; Aruffo, E.; Moller, S. J.; S. J.-B. Bauguitte; Allan, J. D.

    2013-01-01

    We present an analysis of ozone photochemistry observed by aircraft measurements of boreal biomass burning plumes over Eastern Canada in the summer of 2011. Measurements of ozone and a number of key chemical species associated with ozone photochemistry, including non-methane hydrocarbons (NMHCs), nitrogen oxides (NOx) and total nitrogen containing species (NOy), were made from the UK FAAM BAe-146 research aircraft as part of the quantifying ...

  2. Carbon sequestration from boreal wildfires via Pyrogenic Carbon production

    Science.gov (United States)

    Santin, Cristina; Doerr, Stefan; Preston, Caroline

    2014-05-01

    Fire releases important quantities of carbon (C) to the atmosphere. Every year, an average of 460 Million ha burn around the globe, generating C emissions equivalent to a third of the current annual contribution from fossil fuel combustion. Over the longer-term wildfires are widely considered as 'net zero C emission events', because C emissions from fires, excluding those associated with deforestation and peatland fires, are balanced by C uptake by regenerating vegetation. This 'zero C emission' scenario, however, may be flawed, as it does not consider the production of pyrogenic C (PyC). During fire, part of the biomass C burnt is emitted to the atmosphere but part is transformed into PyC (i.e. charcoal). The enhanced resistance of PyC to environmental degradation compared to unburnt biomass gives it the potential to sequester C over the medium/long term. Therefore, after complete regeneration of the vegetation, the PyC generated may represent an additional C pool and, hence, recurring fire-regrowth cycles could represent net sinks of atmospheric C. To estimate the quantitative importance of PyC production, accurate data on PyC generation with respect to the fuel combusted are needed. Unfortunately, detailed quantification of fuel prior to fire is normally only available for prescribed and experimental fires, which are usually of low-intensity and therefore not representative of higher-intensity wildfires. Furthermore, what little data is available is usually based on only a specific fraction of the PyC present following burning rather than the whole range of PyC products and pools (i.e. PyC in soil, ash, downed wood and standing vegetation). To address this research gap, we utilized the globally unique FireSmart experimental forest fires in Northwest Canada. They are aimed to reproduce wildfire conditions typical for boreal forest and, at the same time, allow pre-fire fuel assessment, fire behaviour monitoring and immediate post-fire fuel and PyC inventory. This

  3. Decadal change in the boreal summer intraseasonal oscillation

    Science.gov (United States)

    Yamaura, Tsuyoshi; Kajikawa, Yoshiyuki

    2016-06-01

    A decadal change in activity of the boreal summer intraseasonal oscillation (BSISO) was identified at a broad scale. The change was more prominent during August-October in the boreal summer. The BSISO activity during 1999-2008 (P2) was significantly greater than that during 1984-1998 (P1). Compared to P1, convection in the BSISO was enhanced and the phase speed of northward-propagating convection was reduced in P2. Under background conditions, warm sea surface temperature (SST) anomalies in P2 were apparent over the tropical Indian Ocean and the western tropical Pacific. The former supplied favorable conditions for the active convection of the BSISO, whereas the latter led to a strengthened Walker circulation through enhanced convection. This induced descending anomalies over the tropical Indian Ocean. Thermal convection tends to be suppressed by descending anomalies, whereas once an active BSISO signal enters the Indian Ocean, convection is enhanced through convective instability by positive SST anomalies. After P2, the BSISO activity was weakened during 2009-2014 (P3). Compared to P2, convective activity in the BSISO tended to be inactive over the southern tropical Indian Ocean in P3. The phase speed of the northward-propagating convection was accelerated. Under background conditions during P3, warmer SST anomalies over the maritime continent enhance convection, which strengthened the local Hadley circulation between the western tropical Pacific and the southern tropical Indian Ocean. Hence, the convection in the BSISO over the southern tropical Indian Ocean was suppressed. The decadal change in BSISO activity correlates with the variability in seasonal mean SST over the tropical Asian monsoon region, which suggests that it is possible to predict the decadal change.

  4. Caesium-137 in a boreal forest ecosystem. Aspects on the long-term behaviour

    International Nuclear Information System (INIS)

    Cycling of radioactive caesium, particularly the isotope Cs-137, is studied in boreal forest biotopes mainly located at the Vindeln experimental forest, 60 km NW of Umeaa, Sweden, (64 degrees 16'N, 19 degrees 48'E). The distribution of radioactive caesium in this forest ecosystem, prior to and in different periods after the Chernobyl accident, reflects the existence of fast changes particularly at an early stage after the deposition, superimposed on slow redistribution over long time periods. The definite causes to this complex dynamic behaviour are not yet unambiguously established. In this work we use the specific results from local field studies as a basis to describe the general pattern and time dependence of Cs-137 redistribution in a boreal forest. We raise the hypothesis that: 'Cs-137 present in a boreal forest tends towards a homogenous distribution among the living cells of that system'. This hypothesis is based on physiological characteristics concerning transport over cell membranes and intracellular distribution in comparison to potassium, and the apparently conservative conditions prevailing for caesium in boreal ecosystems - e.g. the facts that very little of the radioactive caesium deposited over the forest area is lost from the system by run off, more than 90% of the total deposition of Cs-137 resides in the upper organic horizon in podzol areas, and that the availability in the ecosystem, as can be seen from the Cs-137 concentration in moose meat, is not significantly different in 1985 (i.e. prior to the Chernobyl accident) in comparison to the period 1986-1990. The aim of this work is to elucidate how predictions, based on our hypothesis about redistribution processes in the boreal forest, corroborates with the main features in the time-dependent change of Cs-137 activity, according to measurements on perennial vegetation from the local sites. In particular the implicit dependence of the dynamics of the redistribution processes on primary

  5. Ecohydrology of Interior Alaska boreal forest systems

    Science.gov (United States)

    Cable, J.; Bolton, W. R.

    2012-12-01

    The ecohydrology of boreal forest ecosystems of Interior Alaska is not well understood largely because of challenges posed by the presence of discontinuous permafrost. Near-surface permafrost results in storage-dominated systems with cold, poorly drained soils, and slow growing, low statured coniferous trees (Picea mariana) or CDE's. The transition to permafrost-free areas can occur over a few meters and is accompanied by a vegetation community dominated by large deciduous trees (Populus sp. and Betula sp.) or DDE's. Typically, areas with permafrost are on north facing slopes and valley bottoms, and areas without permafrost are south facing. In Alaska's boreal forest, the permafrost is very warm and vulnerable to the effects of climate change. Once permafrost begins to thaw, the vegetation community shifts from coniferous to deciduous dominated. Streamflow in watersheds with a larger permafrost distribution tends to be higher and more responsive to precipitation events than in watersheds with low permafrost distribution. In fact, precipitation events in the low permafrost areas do not infiltrate past the rooting zone of the deciduous trees (~5-40 cm). This suggests that the deciduous trees may remove water from the system via uptake and transpiration. We focus on how vegetation water use affects boreal forest hydrology in areas of discontinuous permafrost. Specifically, we ask: what are the patterns of vegetation water use in areas with and without permafrost? This study focuses on the CDE and DDE systems. Our research sites are established on low and high locations on each aspect (south facing DDE, north facing CDE) to capture the variability associated with the different hillside drainage properties. At each of the four sites during the growing season, we measured various aspects of plant water use dynamics, including water flux, water content, water sources, depth of water uptake in the soil, and water stress. We use a Bayesian framework to analyze the data. We

  6. Contrasting preferences of arbuscular mycorrhizal and dark septate fungi colonizing boreal and subarctic Avenella flexuosa.

    Science.gov (United States)

    Kauppinen, M; Raveala, K; Wäli, P R; Ruotsalainen, A L

    2014-04-01

    Arbuscular mycorrhizal (AM) and dark septate endophytic (DSE) fungi are ubiquitous in grass roots, but their colonizations may vary according to latitudinal gradient and site conditions. We investigated how vegetation zone (boreal vs. subarctic), humus thickness, and site openness affect root fungal colonizations of the grass Avenella flexuosa. More precisely, we hypothesized that AM and DSE fungal colonizations would have different responses to environmental conditions such that AM fungi could be more common in boreal zone, whereas we expected DSE fungi to be more affected by the amount of humus. We found site openness to affect AM and DSE fungi in a contrasting manner, in interaction with the vegetation zone. AM colonization was high at open coastal dunes, whereas DSE fungi were more common at forested sites, in the boreal zone. Humus thickness affected AM fungi negatively and DSE fungi positively. To conclude, the observed AM and DSE fungal colonization patterns were largely contrasting. AM fungi were favored in seashore conditions characterized by thin humus layer, whereas DSE fungi were favored in conditions of higher humus availability. PMID:24061928

  7. Forest commons in boreal Sweden

    OpenAIRE

    Holmgren, Eva

    2009-01-01

    This thesis examines the influences of Swedish forest commons on forest condition, management and the local economy. The approach is rationalistic, i.e. outcomes of forestry activities are assessed in relation to aims. According to the stated objectives, forest commons should serve as exemplars for improved forest management, focusing on increased and sustained timber production. They should provide sustainable economic support for farmers and the local economy, providing a sound basis for ta...

  8. Examining mechanisms in the final stages of the elimination of boreal tree species on vulnerable sites in boreal Alaska

    Science.gov (United States)

    Juday, G. P.; Jess, R.; Alix, C. M.; Verbyla, D.

    2015-12-01

    The boreal forest of Alaska and western Canada exist in a complex mosaic of environments determined by elevation, aspect of exposure, and longitudinal and latitudinal gradients of change from warm, dry continental to maritime-influenced conditions. This forest region is largely made up of trees with two growth responses to temperature increases. Trees that decrease in growth are termed negative responders, and occupy warm, dry sites at low elevations. Trees that increase in radial growth are termed positive responders, and are largely in western Alaska, and at high elevation of the Brooks and Alaska Ranges. Since the Pacific climate regime shift of the 1970s, mature trees at low elevation sites have experienced increasing climate stress in several quasi-decadal cycles of intensifying drought stress. NDVI trends and tree ring records demonstrating radial growth decline are coherent. Phenological monitoring of spruce height growth also indicates that depletion of spring soil moisture is a critical process driven by the interaction of early warm season temperatures and precipitation. Novel biotic disturbance agents including spruce budworm, outbreaks of which are triggered by warm temperature anomalies related to its biology, and aspen leaf miner are depressing realized growth below climatically predicted levels, suggesting a pathway by which tree death is likely to occur before absolute temperature limits. As a result, insect outbreaks are degrading the otherwise strong long-term climate signal in Alaska boreal trees. However, young tree (> 40 yrs.) regeneration generally does not yet display the symptoms of acute high temperature stress. Overall, on these vulnerable sites, if temperature increases similar to the past 40 years continue, long term survival prospects are questionable because the climate conditions would be outside the limits that have historically defined the species ranges of aspen, Alaska birch, and black and white spruce.

  9. Disturbance legacies and climate jointly drive tree growth and mortality in an intensively studied boreal forest

    OpenAIRE

    B. Bond-Lamberty; Rocha, AV; K. Calvin; Holmes, B; Wang, C; Goulden, ML

    2014-01-01

    Most North American forests are at some stage of post-disturbance regrowth, subject to a changing climate, and exhibit growth and mortality patterns that may not be closely coupled to annual environmental conditions. Distinguishing the possibly interacting effects of these processes is necessary to put short-term studies in a longer term context, and particularly important for the carbon-dense, fire-prone boreal forest. The goals of this study were to combine dendrochronological sampling, inv...

  10. Biomass patterns in boreal-subarctic lake food webs along gradients of light and nutrients

    OpenAIRE

    Thomsson, Gustaf

    2015-01-01

    There is large natural variation in light and nutrient conditions across lakes. In the boreal-subarctic region most lakes are small, shallow and nutrient poor. In such lakes there is often sufficient light to support primary production at the lake bottom. An expectation for the future is that colored dissolved organic matter (cDOM) of terrestrial origin will increase in these lakes. cDOM depresses the underwater light climate but is often associated with elevated pelagic nutrient concentratio...

  11. Different management regimes in a boreal forest landscape : ecological and economic effects

    OpenAIRE

    Fries, Clas; Lämås, Tomas

    2000-01-01

    Five management regimes were theoretically applied and evaluated in a 10 000 ha boreal forest landscape. Four regimes were designed to enhance conditions for biodiversity conservation, by establishing reserves and by modifying stand management. One regime was purely for timber production. Effects on biodiversity were assessed in terms of changes in population sizes within species or as number of species within ecological groups of the Red-listed species in the landscape. Assessments were base...

  12. Rendimento da Atriplex nummularia irrigada com efluentes da criação de tilápia em rejeito da dessalinização de água Behavior of saltbush (Atriplex nummularia irrigated with effluents from tilapia raised in brackish water

    Directory of Open Access Journals (Sweden)

    Everaldo R. Porto

    2006-03-01

    Full Text Available Com o objetivo de avaliar a influência no rendimento da erva-sal (Atriplex nummularia e em algumas características do solo, quando irrigada com efluentes da criação de tilápia (Oreochromis sp. em rejeito da dessalinização de água salobra no semi-árido brasileiro, a erva-sal foi irrigada durante um ano com quatro volumes de efluentes na Embrapa Semi-Árido, em Petrolina, PE, cuja salinidade média foi, de 8,29 dS m-1. O delineamento experimental foi de blocos ao acaso com quatro tratamentos e três repetições. Os tratamentos T1, T2, T3 e T4 correspondem, respectivamente, aos volumes de efluentes aplicados semanalmente, de 75, 150, 225 e 300 L planta-1 . A salinidade média do solo na profundidade 0 - 90 cm foi de 0,40 dS m-1, antes de serem iniciadas as irrigações. Após a colheita, respectivamente para os tratamentos T1, T2, T3 e T4, as salinidades médias dos perfis de solo na mesma profundidade (0 - 90 cm foram de 8,02, 6,09, 4,97 e 4,60 dS m-1 e os rendimentos de matéria seca da erva-sal, de 9,75, 12,26, 14,49 e 13,81 t ha-1. O maior rendimento de matéria seca por litro de efluente aplicado foi para o tratamento T1, com 4,84 g L-1 que apresentou, também, a melhor relação entrada/saída de sal, removendo 13,84% do total de sal incorporado ao solo.Looking forward to reduce environmental impacts resulting from desalinization of brackish water in the region of the crystalline rocks in the semi-arid Brazil, saltbush (Atriplex nummularia was cultivated during one year with four different volumes of aquiculture effluent generated from an intensive tilapia (Oreochromis sp raising system, with a mean salinity of 8.29 dS m-1, in an experimental field of Embrapa Semi-Arid. A completely randomized block design, with four treatments and three replications was used. The treatments T1, T2, T3 and T4 corresponded, respectively, to the weekly volumes of irrigation of 75, 150, 225 and 300 L of water per plant. The mean soil salinity of the

  13. Forest productivity decline caused by successional paludification of boreal soils.

    Science.gov (United States)

    Simard, Martin; Lecomte, Nicolas; Bergeron, Yves; Bernier, Pierre Y; Paré, David

    2007-09-01

    Long-term forest productivity decline in boreal forests has been extensively studied in the last decades, yet its causes are still unclear. Soil conditions associated with soil organic matter accumulation are thought to be responsible for site productivity decline. The objectives of this study were to determine if paludification of boreal soils resulted in reduced forest productivity, and to identify changes in the physical and chemical properties of soils associated with reduction in productivity. We used a chronosequence of 23 black spruce stands ranging in postfire age from 50 to 2350 years and calculated three different stand productivity indices, including site index. We assessed changes in forest productivity with time using two complementary approaches: (1) by comparing productivity among the chronosequence stands and (2) by comparing the productivity of successive cohorts of trees within the same stands to determine the influence of time independently of other site factors. Charcoal stratigraphy indicates that the forest stands differ in their fire history and originated either from high- or low-severity soil burns. Both chronosequence and cohort approaches demonstrate declines in black spruce productivity of 50-80% with increased paludification, particularly during the first centuries after fire. Paludification alters bryophyte abundance and succession, increases soil moisture, reduces soil temperature and nutrient availability, and alters the vertical distribution of roots. Low-severity soil burns significantly accelerate rates of paludification and productivity decline compared with high-severity fires and ultimately reduce nutrient content in black spruce needles. The two combined approaches indicate that paludification can be driven by forest succession only, independently of site factors such as position on slope. This successional paludification contrasts with edaphic paludification, where topography and drainage primarily control the extent and rate

  14. Comparative Modeling Studies of Boreal Water and Carbon Balance

    Science.gov (United States)

    Coughlan, J.; Peterson, David L. (Technical Monitor)

    1997-01-01

    The coordination of the modeling and field efforts for an Intensive Field Campaign (IFC) may resemble the chicken and egg dilemma. This session's theme advocates that early and proactive involvement by modeling teams can produce a scientific and operational benefit for the IFC and Experiment. This talk will provide some examples and suggestions originating from the NASA funded IFC's of the FIFE First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment, Oregon Transect Ecosystem Research (OTTER) and predominately Boreal Ecosystem-Atmosphere Study (BOREAS) Experiments. In February 1994 and prior to the final selection of the BOREAS study sites, a group of funded BOREAS investigators agreed to run their models with data for five community types representing the proposed tower flux sites. All participating models were given identical initial values and boundary conditions and driven with identical climate data. The objectives of the intercomparison exercise were: 1) compare simulation results of participating terrestrial, hydrological, and atmospheric models over selected time frames; 2) learn about model behavior and sensitivity to estimated boreal site and vegetation definitions; 3) prioritize BOREAS field data collection efforts supporting modeling studies; 4) identify individual model deficiencies as early as possible. Out of these objectives evolved some important coordination and science issues for the BOREAS Experiment that can be generalized to IFCs and long term archiving of the data. Some problems are acceptable because they are endemic to maintaining fair and open competition prior to the peer review process. Others are logistical and addressable through application of planning, management, and information sciences. This investigator has identified one source of measurement and model incompatibility that is manifest in the IFC scaling approach. Although intuitively obvious, scaling problems are already more formally defined in

  15. Boreal Forests of Kamchatka: Structure and Composition

    Directory of Open Access Journals (Sweden)

    Markus P. Eichhorn

    2010-09-01

    Full Text Available Central Kamchatka abounds in virgin old-growth boreal forest, formed primarily by Larix cajanderi and Betula platyphylla in varying proportions. A series of eight 0.25–0.30 ha plots captured the range of forests present in this region and their structure is described. Overall trends in both uplands and lowlands are for higher sites to be dominated by L. cajanderi with an increasing component of B. platyphylla with decreasing altitude. The tree line on wet sites is commonly formed by mono-dominant B. ermanii forests. Basal area ranged from 7.8–38.1 m2/ha and average tree height from 8.3–24.7 m, both being greater in lowland forests. Size distributions varied considerably among plots, though they were consistently more even for L. cajanderi than B. platyphylla. Upland sites also contained a dense subcanopy of Pinus pumila averaging 38% of ground area. Soil characteristics differed among plots, with upland soils being of lower pH and containing more carbon. Comparisons are drawn with boreal forests elsewhere and the main current threats assessed. These forests provide a potential baseline to contrast with more disturbed regions elsewhere in the world and therefore may be used as a target for restoration efforts or to assess the effects of climate change independent of human impacts.

  16. Tree species richness decreases while species evenness increases with disturbance frequency in a natural boreal forest landscape.

    Science.gov (United States)

    Yeboah, Daniel; Chen, Han Y H; Kingston, Steve

    2016-02-01

    Understanding species diversity and disturbance relationships is important for biodiversity conservation in disturbance-driven boreal forests. Species richness and evenness may respond differently with stand development following fire. Furthermore, few studies have simultaneously accounted for the influences of climate and local site conditions on species diversity. Using forest inventory data, we examined the relationships between species richness, Shannon's index, evenness, and time since last stand-replacing fire (TSF) in a large landscape of disturbance-driven boreal forest. TSF has negative effect on species richness and Shannon's index, and a positive effect on species evenness. Path analysis revealed that the environmental variables affect richness and Shannon's index only through their effects on TSF while affecting evenness directly as well as through their effects on TSF. Synthesis and applications. Our results demonstrate that species richness and Shannon's index decrease while species evenness increases with TSF in a boreal forest landscape. Furthermore, we show that disturbance frequency, local site conditions, and climate simultaneously influence tree species diversity through complex direct and indirect effects in the studied boreal forest. PMID:26865971

  17. Dioxins, PCBs, and HCB in soil and peat profiles from a pristine boreal catchment

    International Nuclear Information System (INIS)

    The aim of this study was to explore how atmospherically derived soil pollution is affected by environmental processes at two typical boreal catchment landscape type settings: wetlands and forested areas. Measurements of hydrophobic organic compounds (HOCs) in forest soil and peat from an oligotrophic mire at various depths were performed at a remote boreal catchment in northern Sweden. HOCs in peat were evenly distributed throughout the body of the mire while levels of HOCs in the forest soil increased with increased amount of organic matter. Evaluation of HOC composition by principal component analysis (PCA) showed distinct differences between surface soils and deeper soil and peat samples. This was attributed to vertical transport, degradation and/or shifting sources over time. The calculated net vertical transport differed between surface layers (0.3%) and deeper soils (8.0%), suggesting that vertical transport conditions and processes differ in the deeper layers compared to the surface layers. - Two typical boreal landscape types, wetlands and forested areas, show different vertical distribution and net vertical transport of HOCs.

  18. Enzyme activity and microorganisms diversity in soil contaminated with the Boreal 58 WG herbicide.

    Science.gov (United States)

    Kucharski, Jan; Tomkiel, Monika; Baćmaga, Małgorzata; Borowik, Agata; Wyszkowska, Jadwiga

    2016-07-01

    Next-generation herbicides are relatively safe when used properly, but the recommended rates are relatively low, which can lead to overdosing. This study evaluated the responses of soil-dwelling microorganisms and soil enzymes to contamination with the Boreal 58 WG herbicide. The analyzed product contains active ingredients flufenacet and isoxaflutole. All tests were performed under laboratory conditions. The analyzed material was sandy clay. Boreal 58 WG was introduced to soil in four doses. Soil without the addition of the herbicide served as the control. The soil was mixed with the tested herbicide, and its moisture content was maintained at 50% of capillary water capacity. Biochemical and microbiological analyses were performed on experimental days 0, 20, 40, 80 and 160. Accidental contamination of soil with the Boreal 58 WG herbicide led to a relatively minor imbalance in the soil microbiological and biochemical profile. The herbicide dose influenced dehydrogenase activity in only 0.84%, urease activity in 2.04%, β-glucosidase activity in 8.26%, catalase activity in 12.40%, arylsulfatase activity in 12.54%, acid phosphatase activity in 42.11%, numbers of organotrophic bacteria in 18.29%, actinomyces counts in 1.31% and fungi counts in 6.86%. PMID:27050595

  19. Divergent Arctic-Boreal Vegetation Changes between North America and Eurasia over the Past 30 Years

    Directory of Open Access Journals (Sweden)

    Arindam Samanta

    2013-05-01

    Full Text Available Arctic-Boreal region—mainly consisting of tundra, shrub lands, and boreal forests—has been experiencing an amplified warming over the past 30 years. As the main driving force of vegetation growth in the north, temperature exhibits tight coupling with the Normalized Difference Vegetation Index (NDVI—a proxy to photosynthetic activity. However, the comparison between North America (NA and northern Eurasia (EA shows a weakened spatial dependency of vegetation growth on temperature changes in NA during the past decade. If this relationship holds over time, it suggests a 2/3 decrease in vegetation growth under the same rate of warming in NA, while the vegetation response in EA stays the same. This divergence accompanies a circumpolar widespread greening trend, but 20 times more browning in the Boreal NA compared to EA, and comparative greening and browning trends in the Arctic. These observed spatial patterns of NDVI are consistent with the temperature record, except in the Arctic NA, where vegetation exhibits a similar long-term trend of greening to EA under less warming. This unusual growth pattern in Arctic NA could be due to a lack of precipitation velocity compared to the temperature velocity, when taking velocity as a measure of northward migration of climatic conditions.

  20. Winter climate controls soil carbon dynamics during summer in boreal forests

    International Nuclear Information System (INIS)

    Boreal forests, characterized by distinct winter seasons, store a large proportion of the global terrestrial carbon (C) pool. We studied summer soil C-dynamics in a boreal forest in northern Sweden using a seven-year experimental manipulation of soil frost. We found that winter soil climate conditions play a major role in controlling the dissolution/mineralization of soil organic-C in the following summer season. Intensified soil frost led to significantly higher concentrations of dissolved organic carbon (DOC). Intensified soil frost also led to higher rates of basal heterotrophic CO2 production in surface soil samples. However, frost-induced decline in the in situ soil CO2 concentrations in summer suggests a substantial decline in root and/or plant associated rhizosphere CO2 production, which overrides the effects of increased heterotrophic CO2 production. Thus, colder winter soils, as a result of reduced snow cover, can substantially alter C-dynamics in boreal forests by reducing summer soil CO2 efflux, and increasing DOC losses. (letter)

  1. An urban boreal lake basin as a source of CO2 and CH4

    International Nuclear Information System (INIS)

    Up to now, carbon gas fluxes from urban lakes in the boreal zone have seldom been studied. In summer 2005 we investigated fluxes from an urban boreal lake basin in southern Finland with long history of eutrophication and anoxia. Hypolimnetic CO2 and CH4 concentrations were high compared to other boreal lakes. During the open-water period, the lake basin acted as a source of CO2 and CH4 with fluxes of 2.10 mol m-2 and 0.04 mol m-2, respectively. Despite the high oxidation rate (83%), CH4 flux was higher than in other lakes and CH4 contributed 60% to Global Warming Potential. The ratio of carbon emission to accumulation was 4, i.e. emissions were an important route for carbon departure but less so than in rural lakes. Since the lake oxygen conditions affected nutrient availability, there was a positive feedback from hypolimnion to carbon uptake, which was reflected in gas concentrations. - Highlights: → Hypolimnetic CH4 concentrations were higher in the urban lake vs rural lake. → The water basin was a steady source of CO2 and CH4. The annual GWP was due to CH4. → CH4 fluxes were high despite CH4 oxidation i.e. 83%. → Gas emission to carbon accumulation ratio was 4, thus sedimentation was important. → Limiting resources differ between urban and rural lakes during stratification. - Urbanization in the studied boreal lake was reflected in higher than normal hypolimnetic CO2 and CH4 concentrations resulting in considerable carbon gas fluxes, especially in terms of CH4.

  2. Upscaling methane emission hotspots in boreal peatlands

    Science.gov (United States)

    Cresto Aleina, Fabio; Runkle, Benjamin R. K.; Bruecher, Tim; Kleinen, Thomas; Brovkin, Victor

    2016-04-01

    Small-scale surface heterogeneities can influence land-atmosphere fluxes and therefore carbon, water and energy budgets on a larger scale. This effect is of particular relevance for high-latitude ecosystems, because of the great amount of carbon stored in their soils. Upscaling such small-scale surface heterogeneities and their effects to larger scales is a challenging issue in land surface modeling. We developed a novel approach to upscale local methane emissions in a boreal peatland from the micro-topographic scale to the landscape-scale. We based this parameterization on the analysis of the water table pattern generated by the Hummock-Hollow model (Cresto Aleina et al., 2015), a micro-topography resolving model for peatland hydrology and methane emissions. By computing the water table at the micro-topographic scale, the Hummock-Hollow model is able to describe the effects of micro-topography on hydrology and methane emissions in a typical boreal peatland. We introduce the new parameterization of methane hotspots in a global model-like version of the Hummock-Hollow model. This latter version underestimates methane emissions because of the lack of representation of micro-topographic controls on peatland hydrology. We tested the robustness of the parameterization by simulating methane emissions for the present day and for the next century, forcing the model with three different RCP scenarios. The Hotspot parameterization, despite being calibrated for the 1976-2005 climatology, mimics the output of the micro-topography resolving model for all the simulated scenarios. The new approach bridges the scale gap of methane emissions between this version of the model and the configuration explicitly resolving micro-topography.

  3. Bryophyte Evapotranspiration in a Boreal Forest Chronosequence

    Science.gov (United States)

    Bond-Lamberty, B.; Ewers, B.; Angstmann, J.; Gower, S.

    2008-12-01

    Forest water fluxes, in particular evapotranspiration (ET), are less well constrained than are carbon fluxes, and the effect of changing stand age on forest ET is not well understood. We combined field and lab measurements to estimate the bryophyte contribution to ET in a black spruce-dominated boreal chronosequence in Manitoba, Canada. Site ages were 17, 42, 76 and 156 years, and each site contained separate well- and poorly-drained stands (bogs). Field plots (N=4) were surveyed for moss diversity and microtopography; meteorological variables were recorded continuously. Field measurements were made 3-4 times during the growing season using a custom chamber attached to a LI-COR 6400. In addition, large tubs of moss were incubated in a controlled-environment chamber and water loss rates measured via weighing; these tubs were also measured using the same protocol as performed in the field. In the lab, fully-saturated feathermoss and Sphagnum lost water at rates as high as 1.5 and 4.5 mm day-1, respectively, at 25 °C. Over the entire year, modeled bryophyte ET ranged from 0.2-0.3 and 0.2-0.5 mm day-1 in the well- and poorly-drained stands, respectively. During the growing season, these rates were 0.7-0.8 and 0.6- 1.4 mm day-1. Ignoring bog microtopography would have resulted in underestimation of fluxes by ~10%. There was no clear trend of moss ET flux with stand age, except at the very youngest stands, where bryophyte spatial coverage was low. Our results emphasize the important contribution that bryophytes make to the ET flux of boreal forests.

  4. Black (pyrogenic carbon: a synthesis of current knowledge and uncertainties with special consideration of boreal regions

    Directory of Open Access Journals (Sweden)

    C. M. Preston

    2006-01-01

    wildfires, and little direct information on rates and mechanisms for PyC loss. Structural characterization of charred biomass and forest floor from wildfires generally indicates a low level of thermal alteration, with the bulk of the material having H/C ratios still >0.2, and small aromatic cluster sizes. Especially for the more oxidation-resistant BC fraction, a variety of mainly circumstantial evidence suggests very slow decomposition, with turnover on a millennial timescale (in the order of 5–7 ky, also dependent on environmental conditions. However, there is also evidence that some PyC may be lost in only tens to hundreds of years due to a combination of lower thermal alteration and environmental protection. The potential for long-term PyC storage in soil may also be limited by its consumption by subsequent fires. Degraded, functionalized PyC is also incorporated into humified soil organic matter, and is transported eventually to marine sediments in dissolved and particulate form. Boreal production is estimated as 7–17 Tg BC y−1 of solid residues and 2–2.5 Tg BC y−1 as aerosols, compared to global estimates of 40–240 and 10–30 Tg BC y−1, respectively. Primary research needs include basic field data on PyC production and stocks in boreal forests and peatlands, suitable to support C budget modeling, and development of standardized analytical methods and of improved approaches to assess the chemical recalcitrance of typical chars from boreal wildfires. To accomplish these goals effectively will require much greater emphasis on interdisciplinary cooperation.

  5. Black (pyrogenic carbon in boreal forests: a synthesis of current knowledge and uncertainties

    Directory of Open Access Journals (Sweden)

    C. M. Preston

    2006-02-01

    thermal alteration, with the bulk of the material having H/C ratios still >0.2, and small aromatic cluster sizes. For the more chemically-recalcitrant BC fraction, a variety of mainly circumstantial evidence suggests very slow decomposition, with turnover on a millennium timescale (5000–10 000 y, depending on environmental conditions and PyC properties, but the main limitation to PyC storage in soil is likely consumption by subsequent fires. Degraded, functionalized PyC is also incorporated into humified soil organic matter, and is transported to sediments in dissolved and particulate form. Boreal production is estimated as 7–17 Tg BC y−1 of solid residues and 2–2.5 Tg BC y−1 as aerosols. Primary research needs include basic field data on PyC production and stocks in boreal forests and peatlands, suitable to support C budget modeling, and development of standardized analytical methods and of improved approaches to assess the chemical recalcitrance of typical chars from boreal wildfires. To accomplish these goals effectively will require much greater emphasis on interdisciplinary cooperation.

  6. Atmospheric ions, boreal forests and impacts on climate

    Science.gov (United States)

    Manninen, H. E.; Nieminen, T.; Franchin, A.; Järvinen, E.; Kontkanen, J.; Hirsikko, A.; Hõrrak, U.; Mirme, A.; Tammet, H.; Kerminen, V.-M.; Petäjä, T.; Kulmala, M.

    2012-04-01

    than 2 nm in diameter by charging the aerosol sample with unipolar corona chargers (Manninen et al., 2009). According to earlier studies, the atmospheric nucleation and cluster activation take place at the mobility diameter range of 1.5-2 nm. Therefore, the ion spectrometers allow direct measurements at exactly the size where atmospheric nucleation takes place. The results indicate that the ion-induced nucleation contributes ~1-30% to the NPF events in most atmospheric conditions (Manninen et al., 2010). In other words, neutral particle formation seems to dominate over ion-mediated mechanisms, at least in the boreal forest conditions. Acknowledgements. This research was supported by the Academy of Finland Center of Excellence program (project number 1118615). Hirsikko, A. et al.: Atmospheric ions and nucleation: a review of observations, Atmos. Chem. Phys., 11, 767-798, 2011. IPCC, Climate Change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK and New York, NY, USA, 996 pp, 2007. Kulmala, M., and Kerminen, V.-M.: On the growth of atmospheric nanoparticles, Atmos. Res., 90, 132-150, 2008. Manninen, H.E. et al.: Long-term field measurements of charged and neutral clusters using Neutral cluster and Air Ion Spectrometer (NAIS). Boreal Env. Res. 14, 591-605, 2009. Manninen, H.E. et al., EUCAARI ion spectrometer measurements at 12 European sites - analysis of new particle formation events, Atmos. Chem. Phys., 10, 7907-7927, 2010. Mirme, A. et al.: A Wide-range multi-channel Air Ion Spectrometer, Boreal Environ. Res., 12, 247-264, 2007. Tammet, H.: Symmetric inclined grid mobility analyzer for the measurement of charged clusters and fine nanoparticles in atmospheric air. Aerosol Science and Technology, 45, 468 - 479, 2011.

  7. Ozone photochemistry in boreal biomass burning plumes

    Directory of Open Access Journals (Sweden)

    M. Parrington

    2013-01-01

    Full Text Available We present an analysis of ozone photochemistry observed by aircraft measurements of boreal biomass burning plumes over Eastern Canada in the summer of 2011. Measurements of ozone and a number of key chemical species associated with ozone photochemistry, including non-methane hydrocarbons (NMHCs, nitrogen oxides (NOx and total nitrogen containing species (NOy, were made from the UK FAAM BAe-146 research aircraft as part of the quantifying the impact of BOReal forest fires on tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS experiment between 12 July and 3 August 2011. We found that ozone mixing ratios measured in biomass burning plumes were indistinguishable from non-plume measurements, but evaluating them in relationship to measurements of carbon monoxide (CO, total alkyl nitrates (ΣAN and the surrogate species NOz (=NOy - NOx revealed that the potential for ozone production increased with plume age. We used NMHC ratios to estimate photochemical ages of the observed biomass burning plumes between 0 and 15 days. Ozone production, calculated from ΔO3/ΔCO enhancement ratios, increased from 0.020 ± 0.008 ppbv ppbv−1 in plumes with photochemical ages less than 2 days to 0.55 ± 0.29 ppbv ppbv−1 in plumes with photochemical ages greater than 5 days. In comparing ozone mixing ratios with components of the NOy budget we observed that plumes with ages between 2 and 4 days were characterised by high aerosol loading, relative humidity greater than 40%, and low ozone production efficiencies of 8 ppbv ppbv−1 relative to ΣAN and 2 ppbv ppbv−1 relative to NOz. In plumes with ages greater than 4 days, ozone production efficiency increased to 473 ppbv ppbv−1 relative to ΣAN and 155 ppbv ppbv−1 relative to NOz. From the BORTAS measurements we estimated

  8. Ozone photochemistry in boreal biomass burning plumes

    Directory of Open Access Journals (Sweden)

    M. Parrington

    2013-08-01

    Full Text Available We present an analysis of ozone (O3 photochemistry observed by aircraft measurements of boreal biomass burning plumes over eastern Canada in the summer of 2011. Measurements of O3 and a number of key chemical species associated with O3 photochemistry, including non-methane hydrocarbons (NMHCs, nitrogen oxides (NOx and total nitrogen containing species (NOy, were made from the UK FAAM BAe-146 research aircraft as part of the "quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites" (BORTAS experiment between 12 July and 3 August 2011. The location and timing of the aircraft measurements put BORTAS into a unique position to sample biomass burning plumes from the same source region in Northwestern Ontario with a range of ages. We found that O3 mixing ratios measured in biomass burning plumes were indistinguishable from non-plume measurements, but evaluating them in relationship to measurements of carbon monoxide (CO, total alkyl nitrates (ΣAN and the surrogate species NOz (= NOy-NOx revealed that the potential for O3 production increased with plume age. We used NMHC ratios to estimate photochemical ages of the observed biomass burning plumes between 0 and 10 days. The BORTAS measurements provided a wide dynamic range of O3 production in the sampled biomass burning plumes with ΔO3/ΔCO enhancement ratios increasing from 0.020 ± 0.008 ppbv ppbv−1 in plumes with photochemical ages less than 2 days to 0.55 ± 0.29 ppbv ppbv−1 in plumes with photochemical ages greater than 5 days. We found that the main contributing factor to the variability in the ΔO3/ΔCO enhancement ratio was ΔCO in plumes with photochemical ages less than 4 days, and that was a transition to ΔO3 becoming the main contributing factor in plumes with ages greater than 4 days. In comparing O3 mixing ratios with components of the NOy budget, we observed that plumes with ages between 2 and 4 days were characterised

  9. Towards a Manitoba Hydro boreal woodland caribou strategy: Outcomes from Manitoba Hydro boreal woodland caribou workshop

    Directory of Open Access Journals (Sweden)

    Fiona E. Scurrah

    2012-03-01

    Full Text Available Manitoba Hydro is responsible for the continued supply of energy to meet the needs of the province and is committed to protecting the environment when planning the construction and operation of its facilities. Corporate policy dictates ongoing improvement of Environmental Management Systems (EMS in order to meet or surpass regulatory requirements. Environmental objectives are reviewed annually and programs are modified when necessary to address improvements in environmental performance. Manitoba Hydro plans and constructs major transmission projects throughout northern Manitoba which includes areas occupied by boreal woodland caribou. In recognition of the potential issues associated with hydro transmission construction in boreal caribou range, Manitoba Hydro hosted an expert workshop on May 8, 2007 to provide objective advice in the development of a draft corporate strategy that effectively directs targeted monitoring and research for environmental assessment and mitigation. The workshop focused on assessing the potential threats to boreal woodland caribou from a transmission line construction and operation perspective, and identifying appropriate approaches in site selection and environmental assessment (SSEA and long-term monitoring and research. A total of nine threat categories were reviewed to determine the degree and magnitude of potential effects that may result from transmission construction and operation; and of the original nine, five final threat categories were delineated. The main elements of the workshop provided strategic approaches for proactive pre-construction monitoring, research on recruitment and mortality for local populations impacted by ROWs and control areas, and various habitat monitoring, management, and mitigation techniques. Research and monitoring priorities have been identified and continued collaboration with Manitoba Conservation and other land users were also identified.

  10. Evidence for nonuniform permafrost degradation after fire in boreal landscapes

    Science.gov (United States)

    Minsley, Burke J.; Pastick, Neal J.; Wylie, Bruce K.; Brown, Dana R. N.; Andy Kass, M.

    2016-02-01

    Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. We present a combination of multiscale remote sensing, geophysical, and field observations that reveal details of both near-surface (1 m) impacts of fire on permafrost. Along 11 transects that span burned-unburned boundaries in different landscape settings within interior Alaska, subsurface electrical resistivity and nuclear magnetic resonance data indicate locations where permafrost appears to be resilient to disturbance from fire, areas where warm permafrost conditions exist that may be most vulnerable to future change, and also areas where permafrost has thawed. High-resolution geophysical data corroborate remote sensing interpretations of near-surface permafrost and also add new high-fidelity details of spatial heterogeneity that extend from the shallow subsurface to depths of about 10 m. Results show that postfire impacts on permafrost can be variable and depend on multiple factors such as fire severity, soil texture, soil moisture, and time since fire.

  11. Aged anthropogenic iodine in a boreal peat bog

    Energy Technology Data Exchange (ETDEWEB)

    Maillant, S. [Laboratoire Sols et Environnement, UMR 1120 INPL-INRA, 54500 Vandoeuvre-les-Nancy (France); Andra, Direction Scientifique, Service Transferts, 1-7 rue Jean Monnet, 92298 Chatenay-Malabry Cedex (France); Sheppard, M.I. [ECOMatters, P.O. Box 430, Pinawa, Manitoba (Canada); Echevarria, G. [Laboratoire Sols et Environnement, UMR 1120 INPL-INRA, 54500 Vandoeuvre-les-Nancy (France)]. E-mail: Guillaume.Echevarria@ensaia.inpl-nancy.fr; Denys, S. [Laboratoire Sols et Environnement, UMR 1120 INPL-INRA, 54500 Vandoeuvre-les-Nancy (France); Andra, Direction Scientifique, Service Transferts, 1-7 rue Jean Monnet, 92298 Chatenay-Malabry Cedex (France); Villemin, G. [Laboratoire Sols et Environnement, UMR 1120 INPL-INRA, 54500 Vandoeuvre-les-Nancy (France); Tekely, P. [Laboratoire de Methodologie RMN, FRE CNRS 2415, Universite Henri Poincare, Nancy 1, Faculte des Sciences, 54506 Vandoeuvre-les-Nancy (France); Leclerc-Cessac, E. [Andra, Direction Scientifique, Service Transferts, 1-7 rue Jean Monnet, 92298 Chatenay-Malabry Cedex (France); Morel, J.L. [Laboratoire Sols et Environnement, UMR 1120 INPL-INRA, 54500 Vandoeuvre-les-Nancy (France)

    2007-05-15

    This in situ study assesses the long term sorption of I in a natural peat bog, a matter that is scarcely addressed but required for safety studies such as for radioactive waste disposal. Fifteen years after the artificial contamination of a boreal peat bog, the groundwater (piezometers), the peat and the vegetation were resampled to determine I distribution with comparison to the initial situation (1989). Spectroscopic analyses (SS-NMR, electronic microscopy and EDX spectroscopy) were carried out on the peat solids to identify the sorption processes. Over the past 15 a the I has been spreading mostly outwards and possibly upwards in the groundwater. Sorption of I is higher at the surface of the bog (K {sub d} = 37.6 L kg{sup -1}) than at the bottom (K {sub d} = 5.1 L kg{sup -1}), and this is attributed to the oxic/anoxic conditions of the peat layers. The average surface K {sub d} values showed more than a 2-fold increase after 15 a. TEM-EDX analyses of the surface peat showed here for the first time that I was only associated with natural polyphenolic substances contained in humified plant tissues. Plants growing in the bog have not taken up much I with the exception of sedge species ([I]{sub sedgeleaves} is up to 283 mg kg{sup -1})

  12. Aged anthropogenic iodine in a boreal peat bog

    International Nuclear Information System (INIS)

    This in situ study assesses the long term sorption of I in a natural peat bog, a matter that is scarcely addressed but required for safety studies such as for radioactive waste disposal. Fifteen years after the artificial contamination of a boreal peat bog, the groundwater (piezometers), the peat and the vegetation were resampled to determine I distribution with comparison to the initial situation (1989). Spectroscopic analyses (SS-NMR, electronic microscopy and EDX spectroscopy) were carried out on the peat solids to identify the sorption processes. Over the past 15 a the I has been spreading mostly outwards and possibly upwards in the groundwater. Sorption of I is higher at the surface of the bog (K d = 37.6 L kg-1) than at the bottom (K d = 5.1 L kg-1), and this is attributed to the oxic/anoxic conditions of the peat layers. The average surface K d values showed more than a 2-fold increase after 15 a. TEM-EDX analyses of the surface peat showed here for the first time that I was only associated with natural polyphenolic substances contained in humified plant tissues. Plants growing in the bog have not taken up much I with the exception of sedge species ([I]sedgeleaves is up to 283 mg kg-1)

  13. Methane metabolism in a stratified boreal lake

    Science.gov (United States)

    Nykänen, Hannu; Peura, Sari; Kankaala, Paula; Jones, Roger

    2013-04-01

    Stratified lakes, typical of the boreal zone, are naturally anoxic from their bottoms. In these lakes methanogenesis can account for up to half of organic matter degradation. However, a major part of the methane (CH4) is oxidized in the water column before reaching the atmosphere. Since methanotrophs use CH4 as their sole carbon and energy source, much CH4-derived carbon is incorporated into their biomass. Microbially produced CH4 has strongly negative δ13C compared to other carbon forms in ecosystems, making it possible to follow its route in food webs. However, only a few studies have estimated the amount of this microbial biomass or its carbon stable isotopic composition due to difficulties in separating it from other biomass or from other carbon forms in the water column. We estimated methanotrophic biomass from measured CH4 oxidation, and δ13C of the biomass from measured δ13C values of CH4, DIC, POM and DOC. An estimate of the fraction of methanotrophs in total microbial biomass is derived from bacterial community composition measurements. The study was made in, Alinen Mustajärvi, a small (area 0.75 ha, maximum depth 6.5 m, mean depth 4.2 m,), oligotrophic, mesohumic headwater lake located in boreal coniferous forest in southern Finland. CH4 and DIC concentrations and their δ13C were measured over the deepest point of the lake at 1 m intervals. 13C of DOM and POM were analyzed from composite samples from epi-, meta-, and hypolimnion. Evasion of CH4 and carbon dioxide from the lake surface to the atmosphere was estimated with boundary layer diffusion equations. CH4oxidation was estimated by comparing differences between observed concentrations and CH4potentially transported by turbulent diffusion between different vertical layers in the lake and also by actual methanotrophy measurements and from vertical differences in δ13C-CH4. The estimate of CH4 production was based on the sum of oxidized and released CH4. Molecular microbiology methods were used to

  14. Logging and Fire Effects in Siberian Boreal Forests

    Science.gov (United States)

    Kukavskaya, E.; Buryak, L.; Ivanova, G.; Kalenskaya, O.; Bogorodskaya, A.; Zhila, S.; McRae, D.; Conard, S. G.

    2013-12-01

    The Russian boreal zone supports a huge terrestrial carbon pool. Moreover, it is a tremendous reservoir of wood products concentrated mainly in Siberia. The main natural disturbance in these forests is wildfire, which modifies the carbon budget and has potentially important climate feedbacks. In addition, both legal and illegal logging increase landscape complexity and fire hazard. We investigated a number of sites in different regions of Siberia to evaluate the impacts of fire and logging on fuel loads, carbon emissions, tree regeneration, soil respiration, and microbocenosis. We found large variations of fire and logging effects among regions depending on growing conditions and type of logging activity. Partial logging had no negative impact on forest conditions and carbon cycle. Illegal logging resulted in increase of fire hazard, and higher carbon emissions than legal logging. The highest fuel loads and carbon emissions were found on repeatedly burned unlogged sites where first fire resulted in total tree mortality. Repeated fires together with logging activities in drier conditions and on large burned sites resulted in insufficient regeneration, or even total lack of tree seedlings. Soil respiration was less on both burned and logged areas than in undisturbed forest. The highest structural and functional disturbances of the soil microbocenosis were observed on logged burned sites. Understanding current interactions between fire and logging is important for modeling ecosystem processes and for managers to develop strategies of sustainable forest management. Changing patterns in the harvest of wood products increase landscape complexity and can be expected to increase emissions and ecosystem damage from wildfires, inhibit recovery of natural ecosystems, and exacerbate impacts of wildland fire on changing climate and air quality. The research was supported by NASA LCLUC Program, RFBR grant # 12-04-31258, and Russian Academy of Sciences.

  15. Towards sustainable management of boreal forest

    Energy Technology Data Exchange (ETDEWEB)

    Burton, P. J. [Symbios Research and Restoration, Smithers, BC (Canada); Messier, C. [Universite de Quebec a Montreal, GREFi, Dept. of Biological Sciences, Montreal, PQ (Canada); Smith, D. W. [Alberta Univ., Dept. of Civil and Environmental Engineering, Edmonton, AB (Canada); Adamowicz, W. L. [Alberta Univ., Sustainable Forest Management Network and Dept. of Rural Economy, Edmonton, AB (Canada)] (eds.)

    2003-07-01

    This monograph provides a wide ranging review of all matters pertaining to sustainable forest management, including extended definitions and discussions of the components of sustainability and sustainable development, various concepts of forest management and the role of research in the movement towards sustainable forest management. The book pulls together key concepts and advances in sustainable forest management from around the world, especially those applicable in boreal regions. It attempts to report on the state-of-the-art, some new and as yet unproven ideas, and the most up-to-date basic and applied research on the components of sustainable forest management. The subject is presented in 23 separately authored chapters; each with numerous examples, case studies, and scenarios to demonstrate how various elements of the subject are being implemented. The chapters are divided into five broad areas of related topics. The areas are: (1) the goals of sustainable forest management; (2) the social and economic dimensions of sustainability; (3) forest ecology and management; (4 )minimizing the impacts of forest use and fibre processing; and (5) implementing sustainable forest management. Each chapter has its own bibliography; there is an extensive subject index to the volume as a whole.

  16. Upscaling methane emission hotspots in boreal peatlands

    Directory of Open Access Journals (Sweden)

    F. Cresto Aleina

    2015-10-01

    Full Text Available Upscaling the properties and the effects of small-scale surface heterogeneities to larger scales is a challenging issue in land surface modeling. We developed a novel approach to upscale local methane emissions in a boreal peatland from the micro-topographic scale to the landscape-scale. We based this new parameterization on the analysis of the water table pattern generated by the Hummock–Hollow model, a micro-topography resolving model for peatland hydrology. We introduce this parameterization of methane hotspots in a global model-like version of the Hummock–Hollow model, that underestimates methane emissions. We tested the robustness of the parameterization by simulating methane emissions for the next century forcing the model with three different RCP scenarios. The Hotspot parameterization, despite being calibrated for the 1976–2005 climatology, mimics the output of the micro-topography resolving model for all the simulated scenarios. The new approach bridges the scale gap of methane emissions between this version of the model and the configuration explicitly resolving micro-topography.

  17. The importance of micrometeorological variations for photosynthesis and transpiration in a boreal coniferous forest

    DEFF Research Database (Denmark)

    Schurgers, Guy; Lagergren, F.; Molder, M.;

    2015-01-01

    the importance of vertical variations in light, temperature, CO2 concentration and humidity within the canopy for fluxes of photosynthesis and transpiration of a boreal coniferous forest in central Sweden. A leaf-level photosynthesis-stomatal conductance model was used for aggregating these processes...... between abovecanopy and within-canopy humidity, and despite large gradients in CO2 concentration during early morning hours after nights with stable conditions, neither humidity nor CO2 played an important role for vertical heterogeneity of photosynthesis and transpiration....

  18. Disturbance Regimes and Landscape Heterogeneity in the Boreal Forest

    Science.gov (United States)

    Lyons, E. A.; Sheng, Y.

    2014-12-01

    Circling the northern high latitudes, the boreal forest is the largest contiguous forest ecoregion in the world. Far from a homogeneous carpet of trees, the boreal forest is a patchwork of land cover types including evergreen and deciduous trees, meadows, lakes, and wetlands. Due to its size, location, and structure, the boreal forest is an important component of the regional and global climate system through storage of carbon in cold organic soils and direct influence on the solar energy budget. This study integrates remote sensing and GIS products from different sub-fields working in the pan-Arctic region to investigate fire and permafrost-degradation, the land cover shaping processes that help determine the fate of the boreal forest. These disturbance processes are subject to change with climate and hold the potential for rapid change to the structure of the boreal forest. We identify regions at risk for rapid change, quantify the contributions of different disturbance processes, and analyze patterns of post disturbance recovery.

  19. The Silvics of Some East European and Siberian Boreal Forest Tree Species

    OpenAIRE

    Korzukin, M.D.; Rubinina, A.E.; G. B. Bonan; Solomon, A.M.; Antonovsky, M.Y.

    1989-01-01

    In recent years, the boreal forest has received increased scientific attention in light of projected climatic warming to boreal regions from increased concentrations of atmospheric carbon dioxide. The ecological consequences of such a warming could be significant. However, before the consequences of climatic change can be properly investigated, the ecology of boreal forest tree species must be adequately understood. Though the life-histories of many North American boreal forest tree species a...

  20. Climate Variation and Disturbance Regime Affect Stand Composition and Structure of the Boreal Forests in Southwest Yukon of Canada

    OpenAIRE

    Shyam K. Paudel; Simard, Suzanne W.; Craig R. Nitschke; John L. Innes

    2015-01-01

    The cold and dry boreal forests of the Southwest Yukon are dominated by white spruce (Picea glauca), trembling aspen (Populus tremuloides) and balsam poplar (Populus balsamifera), and the variability in structure and composition of stands depends on the favourability of disturbance, climate and site conditions for stimulating regeneration. In this study, we investigated relationships between stand structure and ecological, climatic and disturbance factors in the southwest Yukon...

  1. Simulating the effects of fire disturbance and vegetation recovery on boreal ecosystem carbon fluxes

    Science.gov (United States)

    Yi, Y.; Kimball, J. S.; Jones, L. A.; Zhao, M.

    2011-12-01

    Fire related disturbance and subsequent vegetation recovery has a major influence on carbon storage and land-atmosphere CO2 fluxes in boreal ecosystems. We applied a synthetic approach combining tower eddy covariance flux measurements, satellite remote sensing and model reanalysis surface meteorology within a terrestrial carbon model framework to estimate fire disturbance and recovery effects on boreal ecosystem carbon fluxes including gross primary production (GPP), ecosystem respiration and net CO2 exchange (NEE). A disturbance index based on MODIS land surface temperature and NDVI was found to coincide with vegetation recovery status inferred from tower chronosequence sites. An empirical algorithm was developed to track ecosystem recovery status based on the disturbance index and used to nudge modeled net primary production (NPP) and surface soil organic carbon stocks from baseline steady-state conditions. The simulations were conducted using a satellite based terrestrial carbon flux model driven by MODIS NDVI and MERRA reanalysis daily surface meteorology inputs. The MODIS (MCD45) burned area product was then applied for mapping recent (post 2000) regional disturbance history, and used with the disturbance index to define vegetation disturbance and recovery status. The model was then applied to estimate regional patterns and temporal changes in terrestrial carbon fluxes across the entire northern boreal forest and tundra domain. A sensitivity analysis was conducted to assess the relative importance of fire disturbance and recovery on regional carbon fluxes relative to assumed steady-state conditions. The explicit representation of disturbance and recovery effects produces more accurate NEE predictions than the baseline steady-state simulations and reduces uncertainty regarding the purported missing carbon sink in the high latitudes.

  2. Spatial climate-dependent growth response of boreal mixedwood forest in western Canada

    Science.gov (United States)

    Jiang, Xinyu; Huang, Jian-Guo; Stadt, Kenneth J.; Comeau, Philip G.; Chen, Han Y. H.

    2016-04-01

    The western Canadian mixedwood boreal forests were projected to be significantly affected by regional drought. However, drought degrees were spatially different across elevations, longitudes and latitudes, which might cause different tree growth responses to climate change in different sub-regions within western Canada. In this way, regional classification of western Canadian boreal forests and understanding spatial tree growth responses to climate might be necessary for future forest management and monitoring. In this paper, tree-ring chronologies of two dominant tree species, trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench.) Voss), were obtained from mixed forest stands distributed across western Canada to study spatial tree growth response to climate based on three regional classification schemes (a phytogeographic sub-region classification, a natural sub-region classification and non-classification). Phytogeographic sub-region classification was estimated based on tree ring samples we collected in this study, while natural sub-region classification was previously developed based on analysis of regional differences in vegetation, soil, site and climate conditions. Results showed that air temperature did not significantly increase, while drought stress became more severe between 1985 to 2010. Relationships between trembling aspen growth and temperature differed between north and south parts of the study area, resulting from spatial difference in water supply. Trembling aspen growth was influenced by temperature or moisture variables of the previous years. White spruce growth was influenced primarily by moisture variables (current or previous year), and response coefficients between white spruce and drought conditions (represented by drought code) were negative in all phytogeographic sub-regions, suggesting that white spruce was more sensitive to drought stress under climate change. As a late-successional dominant species

  3. Effects of climatic changes on carbon dioxide and water vapor fluxes in boreal forest ecosystems of European part of Russia

    International Nuclear Information System (INIS)

    Effects of possible climatic and vegetation changes on H2O and CO2 fluxes in boreal forest ecosystems of the central part of European Russia were quantified using modeling and experimental data. The future pattern of climatic conditions for the period up to 2100 was derived using the global climatic model ECHAM5 (Roeckner et al 2003 The Atmospheric General Circulation Model ECHAM 5. PART I: Model Description, Report 349 (Hamburg: Max-Planck Institute for Meteorology) p 127) with the A1B emission scenario. The possible trends of future vegetation changes were obtained by reconstructions of vegetation cover and paleoclimatic conditions in the Late Pleistocene and Holocene, as provided from pollen and plant macrofossil analysis of profiles in the Central Forest State Natural Biosphere Reserve (CFSNBR). Applying the method of paleoanalogues demonstrates that increasing the mean annual temperature, even by 1-2 deg. C, could result in reducing the proportion of spruce in boreal forest stands by up to 40%. Modeling experiments, carried out using a process-based Mixfor-SVAT model, show that the expected future climatic and vegetation changes lead to a significant increase of net ecosystem exchange (NEE) and gross primary productivity (GPP) of the boreal forests. Despite the expected warming and moistening of the climate, the modeling experiments indicate a relatively weak increase of annual evapotranspiration (ET) and even a reduction of transpiration (TR) rates of forest ecosystems compared to present conditions.

  4. Disentangling the responses of boreal stream assemblages to low stressor levels of diffuse pollution and altered channel morphology.

    Science.gov (United States)

    Turunen, Jarno; Muotka, Timo; Vuori, Kari-Matti; Karjalainen, Satu Maaria; Rääpysjärvi, Jaana; Sutela, Tapio; Aroviita, Jukka

    2016-02-15

    Non-point diffuse pollution from land use and alteration of hydromorphology are among the most detrimental stressors to stream ecosystems. We explored the independent and interactive effects of morphological channel alteration (channelization for water transport of timber) and diffuse pollution on species richness and community structure of four organism groups in boreal streams: diatoms, macrophytes, macroinvertebrates, and fish. Furthermore, the effect of these stressors on stream condition was evaluated by Ecological Quality Ratios (EQR) from the national Water Framework Directive (WFD) assessment system. We grouped 91 study sites into four groups that were impacted by either diffuse pollution or hydromorphological alteration, by both stressors, or by neither one. Macroinvertebrate richness was reduced by diffuse pollution, whereas other biological groups were unaltered. Hydromorphological modification had no effect on taxon richness of any of the assemblages. Community structure of all groups was significantly affected by diffuse pollution but not by hydromorphology. Similarly, EQRs indicated negative response by diatoms, macroinvertebrates and fish to diffuse pollution, but not to hydromorphological alteration. Agricultural diffuse pollution thus affected species identities and abundances rather than taxonomic richness. Our results suggest that channelization of boreal streams for timber transport has not altered hydromorphological conditions sufficiently to have a strong impact on stream biota, whereas even moderate nutrient enrichment may be ecologically harmful. Controlling diffuse pollution and associated land use stressors should be prioritized over restoration of in-stream habitat structure to improve the ecological condition of boreal streams. PMID:26706766

  5. Modeling methane emissions from boreal peatlands

    Science.gov (United States)

    Raivonen, Maarit; Smolander, Sampo; Mäkelä, Jarmo; Tomasic, Marin; Aalto, Tuula; Markkanen, Tiina; Susiluoto, Jouni; Kleinen, Thomas; Brovkin, Victor; Rinne, Janne; Lohila, Annalea; Aurela, Mika; Vesala, Timo

    2014-05-01

    Natural wetlands are a significant source of methane (CH4): they have been estimated to account for about 30% of total global CH4 emissions. At the moment, the emission estimates are highly uncertain. These natural emissions respond to climatic variability, so it is necessary to understand their dynamics, in order to be able to predict how they affect the greenhouse-gas balance in the future. We have developed a model of CH4 production and transport in boreal peatlands. The aim is to make it a part of JSBACH, the land component of the Earth System Model of MPI Hamburg. The soil carbon model of JSBACH simulates peatland carbon processes like peat accumulation and decomposition and our CH4 module simulates production of CH4 as a proportion of the anaerobic peat decomposition, transport of CH4 and oxygen between the soil and the atmosphere, and oxidation of CH4 by methanotrophic microbes. The model has the three main pathways for transport: diffusion in aerenchymatous plants and in peat pores (water and air filled) and CH4 ebullition. The oxidation of CH4 depends on the oxygen concentrations in the peat. The model is largely based on existing models of CH4 production and transport but it includes some modifications that we will present here. We also will present the results of the first validations against observational data. The datasets are from two Finnish peatland sites, Siikaneva (southern) and Lompolojänkkä (northern Finland). Measurements of eddy covariance CH4 and CO2 fluxes and meteorological variables, as well as diverse ecological studies have been carried out on both sites over several years.

  6. Regional Assessment of soil organic matter profile distribution in the boreal forest ecosystems of Russia

    Science.gov (United States)

    Meshalkina, Joulia; Belousova, Nataliya; Vasenev, Ivan

    2015-04-01

    Boreal forest ecosystems play one of the key roles in the Global Change challenges responses. The soil carbon stocks are principal regulators of their environmental functions. Boreal forest soil cover is characterized by mutually increased spatial variability in soil organic matter content (SOMC) that one need to take into attention in its current and future environmental functions state assessment including the potential of regional soil organic matter stocks changes due to Global Change and inverse ones. Knowledge of the regional regularities in SOMC profile vertical distribution allows improving their soil environmental functions prediction land quality evaluation. More than 900 profiles of SOMC distribution were studied using the database Boreal that contains data on Russian boreal soils developed in drained conditions on loamy soil forming rocks. These soil profiles belong to seven main types of forest soils of Russian classification and six major regions of Russia. The predomination of accumulation profile type was observed for all cases. Thus the vertical distribution of OMC in the profiles of boreal soils can be described as follow: the layer of maximum OMC is replaced by the layer of dramatic OMC reduction; then the layer of minimal OMC extends up to 2.5 m. The layer of maximal OMC accumulation has the low depth of 5-15 cm. It carried out in different genetic horizons: A1, A1A2, A2, B, AB; sometimes it captures the A2B horizon or the upper part of the illuvial horizon. The OMC in this layer increases from the northern taiga to the southern taiga and from the European part of Russia to Siberia. The second layer is characterized by its depth and by the gradient of OMC decreasing. A great variety of the both parameters is observed. The layer of the sharp OMC fall most often fits with the eluvial horizons A2 or А2В or even the upper part of the Вt (textural) or Bm (metamorphic) horizons. The layer of permanently small OMC may begin in any genetic horizon

  7. Winter radiation extinction and reflection in a boreal pine canopy: measurements and modelling

    International Nuclear Information System (INIS)

    Predicting the rate of snow melt and intercepted snow sublimation in boreal forests requires an understanding of the effects of snow-covered conifers on the exchange of radiant energy. This study examined the amount of intercepted snow on a jack pine canopy in the boreal forest of central Saskatchewan and the shortwave and net radiation exchange with this canopy, to determine the effect of intercepted snow and canopy structure on shortwave radiation reflection and extinction and net radiation attenuation in a boreal forest. The study focused on clear sky conditions, which are common during winter in the continental boreal forest. Intercepted snow was found to have no influence on the clear-sky albedo of the canopy, the extinction of short wave radiation by the canopy or ratio of net radiation at the canopy top to that at the surface snow cover. Because of the low albedo of the snow-covered canopy, net radiation at the canopy top remains positive and a large potential source of energy for sublimation. The canopy albedo declines somewhat as the extinction efficiency of the underlying canopy increases. The extinction efficiency of short wave radiation in the canopy depends on solar angle because of the approximately horizontal orientation of pine branches. For low solar angles above the horizon, the extinction efficiency is quite low and short wave transmissivity through the canopy is relatively high. As the solar angle increases, extinction increases up to angles of about 50°, and then declines. Extinction of short wave radiation in the canopy strongly influences the attenuation of net radiation by the canopy. Short wave radiation that is extinguished by branches is radiated as long wave, partly downwards to the snow cover. The ratio of net radiation at the canopy top to that at the snow cover surface increases with the extinction of short wave radiation and is negative for low extinction efficiencies. For the pine canopy examined, the daily mean net radiation at

  8. Contribution to climate stability via expansion of azonal boreal forests in the Ukrainian Carpathians

    Energy Technology Data Exchange (ETDEWEB)

    Nijnik, M. [Wageningen Univ. (Netherlands). Agricultural Economics and Rural Policy Group

    2002-10-01

    Since World War II, the forests in Ukraine's Carpathian region have suffered over exploitation. The upper border of the Carpathian forests crept to a lower elevation with the contraction of the azonal boreal forests of the Ukraine and the ability of the forests to perform their shelter functions and climate stabilization has decreased. For that reason, Ukraine has initiated a program for afforestation and reforestation which is aimed at planting trees in about 2 million hectares of low-productivity and waste lands and creating forest stands along rivers, canals and water bodies. It is expected that this program will increase the forest area by nearly 20 per cent, considerably improving the environmental situation in the country. Afforestation will lessen the threat of further degradation of the upper layer of fertile soil, and stabilize micro climate conditions as well as the water balance of the rivers. The forest resource base of the country will also increase. This study assessed the potential effects of the expansion of azonal boreal forests in the Carpathians on the carbon cycle and climate stability. It also addressed policy implementation costs. Initially, the study will consider a storage option, where trees are planted for a period of 50 years. Results show that afforestation and reforestation in the Carpathian mountains for the sole purpose of carbon uptake would not be very beneficial. However, the benefit would lie in soil and water protection. Future studies will focus on developing a dynamic optimization model to indicate optimal expansion of azonal boreal forests in the Carpathians. 15 refs., 2 tabs., 4 figs.

  9. Ocean-atmosphere coupling and the boreal winter MJO

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hye-Mi; Hoyos, Carlos D.; Webster, Peter J. [Georgia Institute of Technology, School of Earth and Atmospheric Science, Atlanta, GA (United States); Kang, In-Sik [Seoul National University, School of Earth and Environmental Science, Seoul (Korea, Republic of)

    2010-10-15

    The influence of ocean-atmosphere coupling on the simulation and prediction of the boreal winter Madden-Julian Oscillation (MJO) is examined using the Seoul National University coupled general circulation model (CGCM) and atmospheric - only model (AGCM). The AGCM is forced with daily SSTs interpolated from pentad mean CGCM SSTs. Forecast skill is examined using serial extended simulations spanning 26 different winter seasons with 30-day forecasts commencing every 5 days providing a total of 598 30-day simulations. By comparing both sets of experiments, which share the same atmospheric components, the influence of coupled ocean-atmosphere processes on the simulation and prediction of MJO can be studied. The mean MJO intensity possesses more realistic amplitude in the CGCM than in AGCM. In general, the ocean-atmosphere coupling acts to improve the simulation of the spatio-temporal evolution of the eastward propagating MJO and the phase relationship between convection (OLR) and SST over the equatorial Indian Ocean and the western Pacific. Both the CGCM and observations exhibit a near-quadrature relationship between OLR and SST, with the former lagging by about two pentads. However, the AGCM shows a less realistic phase relationship. As the initial conditions are the same in both models, the additional forcing by SST anomalies in the CGCM extends the prediction skill beyond that of the AGCM. To test the applicability of the CGCM to real-time prediction, we compute the Real-time Multivariate MJO (RMM) index and compared it with the index computed from observations. RMM1 (RMM2) falls away rapidly to 0.5 after 17-18 (15-16) days in the AGCM and 18-19 (16-17) days in the CGCM. The prediction skill is phase dependent in both the CGCM and AGCM. (orig.)

  10. The influence, implications and feedbacks of an intensifying fire regime in Alaska’s boreal forest

    Science.gov (United States)

    Beck, P. S.; Goetz, S. J.; Mack, M. C.; Alexander, H. D.; Randerson, J. T.; Loranty, M. M.; Jin, Y.

    2009-12-01

    Wildfires are the primary disturbance agent in boreal forests. Fires cause short-lived emissions but are followed by decades of vegetative regrowth with water and nutrient cycling modified relative to pre-fire conditions. In addition, surface characteristics change during both the fire event and the ensuing regrowth, thus modify albedo related radiative forcings. Extreme fire years, in terms of the number and intensity of fires and the extent of area burned, have become more prevalent in Alaska as the climate has warmed. Continuation of this trend suggests a new fire regime is likely to change successional trajectories of the boreal landscape and associated feedbacks to climate. Using a newly developed map of deciduous versus evergreen (D:E) tree cover, and a database of fire events, we investigated how increased fire severity in Alaska promotes successional trajectories that favor increased abundance of deciduous trees. The D:E map was created using MODIS observations at 500m spatial resolution and field data on stand composition, combined with higher resolution Landsat imagery. Our results indicate that burn severity influenced the relative abundance of deciduous and evergreen vegetation in the decades following fire, but varied locally with the length of the growing season and other site conditions. We combined these findings with MODIS-derived albedo products and field observations, as well as with modeled estimates of carbon pools, to estimate the changes in carbon storage and radiative forcings associated with vegetation succession following disturbance over the past half century.

  11. Regional extent of permafrost and boreal forest degradations in the central Yakutia by ALOS-PALSAR and AVNIR2 images

    Science.gov (United States)

    Iijima, Yoshihiro; Fedorov, Alexander; Abe, Konomi; Ise, Hajime; Masuzawa, Tadashi

    2013-04-01

    Wet climate with largely increased in precipitation during summer and snow accumulation during winter had continued 4 years since 2004 winter in eastern Siberia. Soil moisture in the active layer had been significantly increased corresponding with thawing of permafrost near the surface during following years. The perennially water-logged active layer furthermore exacerbated the boreal forest habitat, namely withered and dead forests widely extended in this region. In the present study, we have attempted to extract the region of degraded boreal forest based on the analysis of satellite data in the left and right banks of Lena River near Yakutsk, along with expansion of the water surface area in relation to permafrost degradation. We utilized ALOS-PALSAR and AVNIR2 images taken during 2006 through 2009. After geocoding and noise reduction of PALSAR images, classification of water surface area including water-logged ground was performed with supervised classification using the threshold of a microwave backscattering coefficient. Then, we compared the distribution of the water-logged area between multi-years. In addition, during the same period, supervised classification of grassland and boreal forest was conducted using AVNIR2 images. Then, both classifications were overlaid and the multi-years change in degraded boreal forest due to water-logged conditions was extracted as well. Boreal forest in the left bank of the Lena River distributes on river terrace where density of alas lakes is quite low due to consisting of sandy loam soil with underlying permafrost with less ground ice content. In this area, water surface area expanded in concaved terrain and along the valley year by year in conjunction with change from forest to grassland. On the other hand, forest in the right bank of the Lena River distributed in the region with very high density of alas lakes due to underlying ice rich permafrost. During the same period, alas lakes expanded and boreal forest on the

  12. Adaptation and mitigation strategies in Northern Eurasian boreal forests

    OpenAIRE

    A. Shvidenko; F. Kraxner; Obersteiner, M.; D. Schepaschenko

    2011-01-01

    Boreal forests of Northern Eurasia are experiencing ongoing changes in climate, strong impacts by humans including transformation of previously untouched landscapes, and dramatically accelerating disturbance regimes. Current global and regional climatic models predict for this region the most dramatic climatic change over the globe. Unregulated and often destructive anthropogenic impacts on the environment and natural landscapes may substantially accelerate the negative consequences of climat...

  13. Resilience of Alaska’s boreal forest to climatic change

    Science.gov (United States)

    Chapin, F.S.; McGuire, Anthony; Ruess, R.W.; Hollingsworth, Teresa N.; Mack, M.C.; Johnstone, J.F.; Kasischke, E.S.; Euskirchen, E.S.; Jones, J.B.; Jorgenson, M.T.; Kielland, K.; Kofinas, G.; Turetsky, M.R.; Yarie, J.; Lloyd, A.H.; Taylor, D.L.

    2010-01-01

    This paper assesses the resilience of Alaska’s boreal forest system to rapid climatic change. Recent warming is associated with reduced growth of dominant tree species, plant disease and insect outbreaks, warming and thawing of permafrost, drying of lakes, increased wildfire extent, increased postfire recruitment of deciduous trees, and reduced safety of hunters traveling on river ice. These changes have modified key structural features, feedbacks, and interactions in the boreal forest, including reduced effects of upland permafrost on regional hydrology, expansion of boreal forest into tundra, and amplification of climate warming because of reduced albedo (shorter winter season) and carbon release from wildfires. Other temperature-sensitive processes for which no trends have been detected include composition of plant and microbial communities, long-term landscape-scale change in carbon stocks, stream discharge, mammalian population dynamics, and river access and subsistence opportunities for rural indigenous communities. Projections of continued warming suggest that Alaska’s boreal forest will undergo significant functional and structural changes within the next few decades that are unprecedented in the last 6000 years. The impact of these social–ecological changes will depend in part on the extent of landscape reorganization between uplands and lowlands and on policies regulating subsistence opportunities for rural communities.

  14. Resilience of Alaska's Boreal Forest to Climatic Change

    Science.gov (United States)

    Chapin, F. S., III; McGuire, A. D.; Ruess, R. W.; Hollingsworth, T. N.; Mack, M. C.; Johnstone, J. F.; Kasischke, E. S.; Euskirchen, E. S.; Jones, J. B.; Jorgenson, M. T.; Kielland, K.; Kofinas, G. P.; Turetsky, M. R.; Yarie, J.; Lloyd, A. H.; Taylor, D. L.

    2010-01-01

    This paper assesses the resilience of Alaska s boreal forest system to rapid climatic change. Recent warming is associated with reduced growth of dominant tree species, plant disease and insect outbreaks, warming and thawing of permafrost, drying of lakes, increased wildfire extent, increased postfire recruitment of deciduous trees, and reduced safety of hunters traveling on river ice. These changes have modified key structural features, feedbacks, and interactions in the boreal forest, including reduced effects of upland permafrost on regional hydrology, expansion of boreal forest into tundra, and amplification of climate warming because of reduced albedo (shorter winter season) and carbon release from wildfires. Other temperature-sensitive processes for which no trends have been detected include composition of plant and microbial communities, long-term landscape-scale change in carbon stocks, stream discharge, mammalian population dynamics, and river access and subsistence opportunities for rural indigenous communities. Projections of continued warming suggest that Alaska s boreal forest will undergo significant functional and structural changes within the next few decades that are unprecedented in the last 6000 years. The impact of these social ecological changes will depend in part on the extent of landscape reorganization between uplands and lowlands and on policies regulating subsistence opportunities for rural communities.

  15. Global climate change adaptation: examples from Russian boreal forests

    International Nuclear Information System (INIS)

    The Russian Federation contains approximately 20% of the world's timber resources and more than half of all boreal forests. These forests play a prominent role in environmental protection and economic development at global, national, and local levels, as well as, provide commodities for indigenous people and habitat for a variety of plant and animal species. The response and feedbacks of Russian boreal forests to projected global climate change are expected to be profound. Current understanding of the vulnerability of Russian forest resources to projected climate change is discussed and examples of possible adaptation measures for Russian forests are presented including: (1) artificial forestation techniques that can be applied with the advent of failed natural regeneration and to facilitate forest migration northward; (2) silvicultural measures that can influence the species mix to maintain productivity under future climates; (3) identifying forests at risk and developing special management adaption measures for them: (4) alternative processing and uses of wood and non-wood products from future forests; and (5) potential future infrastructure and transport systems that can be employed as boreal forests shift northward into melting permafrost zones. Current infrastructure and technology can be employed to help Russian boreal forests adapt to projected global environmental change, however many current forest management practices may have to be modified. Application of this technical knowledge can help policymakers identify priorities for climate change adaptation

  16. Moss-nitrogen input to boreal forest soils

    DEFF Research Database (Denmark)

    Rousk, Kathrin; Jones, Davey; DeLuca, Thomas

    2014-01-01

    Cyanobacteria living epiphytically on mosses in pristine, unpolluted areas fix substantial amounts of atmospheric nitrogen (N) and therefore represent a primary source of N in N-limited boreal forests. However, the fate of this N is unclear, in particular, how the fixed N2 enters the soil and bec...

  17. Mosaic boreal landscapes with open and forested wetlands

    International Nuclear Information System (INIS)

    We review patterns and processes important for biodiversity in the Fennoscandian boreal forest, describe man's past and present impact and outline a strategy for conservation. The boreal landscape was earlier characterized by a mosaic of open and forested wetlands and forests. Drainage and felling operation have largely changed that pattern. Several organisms depend upon the landscape mosaic. Natural ecotones between mire and forest provide food resources predictable in space and time contrasting to unpredictable edges in the silvicultured landscape. The mosaic is also a prerequisite for organisms dependent on non-substitutable resources in the landscape. The importance of swamp forests has increased as they function as refugia for earlier more widespread old-growth species. Programmes for maintaining biodiversity in the boreal landscape should include the following points. First, the natural mosaic with open and forested wetlands must be maintained. Second, swamp forests must receive a general protection as they often constitute the only old-growth patches in the landscape. Third, we need to restore earlier disturbance regimes. Present strategy plans for conservation are insufficient, as they imply that a too large proportion of boreal organisms will not be able to survive outside protected areas. Instead, we need to focus more on how to preserve organisms in the man-influenced landscape. As a first step we need to understand how organisms are distributed in landscapes at various spatial scales. We need studies in landscapes where the original mosaic has faced various degrees of fragmentation. (au) 124 refs

  18. Atrazine and terbutryn degradation in deposits from groundwater environment within the boreal region in Lahti, Finland.

    Science.gov (United States)

    Talja, K Marja; Kaukonen, Sanna; Kilpi-Koski, Johanna; Malin, Ismo; Kairesalo, Timo; Romantschuk, Martin; Tuominen, Jari; Kontro, Merja H

    2008-12-24

    The degradation of pesticides atrazine and terbutryn was investigated under aerobic and anaerobic conditions in the northern boreal region subsurface deposits and sterilized controls from the depths of 6.3-21.0 m below the surface and 1.2-16.9 m below the groundwater table. During 1.3-1.7 years of laboratory incubation, atrazine degradation under aerobic conditions varied from rapid (half-live 38 days) to no degradation. Anaerobically, atrazine half-lives were 430-829 days. Organic matter, nitrogen, and lead in deposits correlated positively with the atrazine concentration in groundwater. Aerobic and anaerobic terbutryn half-lives were 193-644 and 266-400 days, respectively. Microbial aerobic atrazine and terbutryn degradation was confirmed in the deep deposits near the water table. Under aerobic conditions, the high amounts of Cr, Mn, Ni, and Zn in deposits decreased the chemical degradation of terbutryn. PMID:19053391

  19. Forest harvest contribution to Boreal freshwater methyl mercury load

    Science.gov (United States)

    Kronberg, Rose-Marie; Drott, Andreas; Jiskra, Martin; Wiederhold, Jan G.; Björn, Erik; Skyllberg, Ulf

    2016-06-01

    Effects of Boreal forest harvest on mercury (Hg) and methyl mercury (MeHg) soil pools and export by stream runoff were quantified by comparing 10 reference watersheds (REFs) covered by >80 year old Norway spruce (Picea abies Karst.) forests with 10 similar watersheds subjected to clear-cutting (CCs). While total Hg soil storage did not change, MeHg pools increased seven times (p = 0.006) in the organic topsoil 2 years after clear-cutting. In undulating terrain, situated above the postglacial marine limit (ML) of the ancient Baltic Sea, the mass ratio between flux-weighted MeHg and dissolved organic carbon (MeHg/DOC) in stream runoff increased 1.8 times (p wetlands. The most robust measure, MeHg/DOC, was used to calculate MeHg loadings to Boreal headwaters. If the forest harvest effect lasts 10 years, clear-cutting increases MeHg runoff by 12-20% in Sweden and 2% in the Boreal zone as a whole. In Sweden, having intensely managed forests, 37% and 56% of MeHg are exported from peatlands and forest soils, respectively, and forest clear-cutting is adding another 6.6%. In the Boreal zone as a whole peatlands and forests soils contribute with 53% and 46%, respectively, and clear-cutting is estimated to add another 1.0%. An expected rapid increase in Boreal forest harvest and disturbance urge for inclusion of land use effects in mercury biogeochemical cycling models at different scales.

  20. Surface pool dynamics and climate in boreal peatland of the La Grande River watershed

    International Nuclear Information System (INIS)

    A study was conducted to investigate the influence of climate on the morphological changes of boreal peatlands of the La Grande (LG) River watershed. In particular, changes in 100 pools from 3 boreal peatlands of different trophic status were examined in relation to their regional meteorological data. Aerial photographs from 1977 and 1999 were used to measure area, perimeter, length and width axes of 35 pools in each of the 3 peatlands from LG1, LG2 and LG3. Results show changes in size and shape of pools during the studied periods. The total area covered by pools decreased between 1977 and 1999. At LG1, a decrease of 246 m2 was measured between 1986 and 1990. At LG2, the total area covered by pools decreased by 3320 m2 between 1984 and 1999, and at LG3 the area decreased by 2634 m2 between 1979 and 1988. The changes appear to be related to seasonal or inter-annual variations of precipitation and evapotranspiration regime. Spatial variability response of pools to changes in hydrological condition indicates their different level of sensitivity

  1. Interactions between hydrology and water chemistry shape bacterioplankton biogeography across boreal freshwater networks.

    Science.gov (United States)

    Niño-García, Juan Pablo; Ruiz-González, Clara; Del Giorgio, Paul A

    2016-07-01

    Disentangling the mechanisms shaping bacterioplankton communities across freshwater ecosystems requires considering a hydrologic dimension that can influence both dispersal and local sorting, but how the environment and hydrology interact to shape the biogeography of freshwater bacterioplankton over large spatial scales remains unexplored. Using Illumina sequencing of the 16S ribosomal RNA gene, we investigate the large-scale spatial patterns of bacterioplankton across 386 freshwater systems from seven distinct regions in boreal Québec. We show that both hydrology and local water chemistry (mostly pH) interact to shape a sequential structuring of communities from highly diverse assemblages in headwater streams toward larger rivers and lakes dominated by fewer taxa. Increases in water residence time along the hydrologic continuum were accompanied by major losses of bacterial richness and by an increased differentiation of communities driven by local conditions (pH and other related variables). This suggests that hydrology and network position modulate the relative role of environmental sorting and mass effects on community assembly by determining both the time frame for bacterial growth and the composition of the immigrant pool. The apparent low dispersal limitation (that is, the lack of influence of geographic distance on the spatial patterns observed at the taxonomic resolution used) suggests that these boreal bacterioplankton communities derive from a shared bacterial pool that enters the networks through the smallest streams, largely dominated by mass effects, and that is increasingly subjected to local sorting of species during transit along the hydrologic continuum. PMID:26849312

  2. Optimal conservation resource allocation under variable economic and ecological time discounting rates in boreal forest.

    Science.gov (United States)

    Mazziotta, Adriano; Pouzols, Federico Montesino; Mönkkönen, Mikko; Kotiaho, Janne S; Strandman, Harri; Moilanen, Atte

    2016-09-15

    Resource allocation to multiple alternative conservation actions is a complex task. A common trade-off occurs between protection of smaller, expensive, high-quality areas versus larger, cheaper, partially degraded areas. We investigate optimal allocation into three actions in boreal forest: current standard forest management rules, setting aside of mature stands, or setting aside of clear-cuts. We first estimated how habitat availability for focal indicator species and economic returns from timber harvesting develop through time as a function of forest type and action chosen. We then developed an optimal resource allocation by accounting for budget size and habitat availability of indicator species in different forest types. We also accounted for the perspective adopted towards sustainability, modeled via temporal preference and economic and ecological time discounting. Controversially, we found that in boreal forest set-aside followed by protection of clear-cuts can become a winning cost-effective strategy when accounting for habitat requirements of multiple species, long planning horizon, and limited budget. It is particularly effective when adopting a long-term sustainability perspective, and accounting for present revenues from timber harvesting. The present analysis assesses the cost-effective conditions to allocate resources into an inexpensive conservation strategy that nevertheless has potential to produce high ecological values in the future. PMID:27262031

  3. Mastodon herbivory in mid-latitude late-Pleistocene boreal forests of eastern North America

    Science.gov (United States)

    Teale, Chelsea L.; Miller, Norton G.

    2012-07-01

    Skeletal remains of the extinct American mastodon have often been found with deposits of short, decorticated twigs intermixed with plant fragments presumed to be gastrointestinal or fecal material. If such deposits are digesta, paleobotanical evidence may be used to analyze mastodon foraging strategy, with implications for assessing habitat selection, ecological roles, and response to environmental change. To identify components of mastodon diet in mid-latitude late-Pleistocene boreall forests of eastern North America, plant macrofossils and pollen from a molar socket (Hyde Park site, New York) were compared with dispersed deposits associated with skeletal remains (Hiscock and Chemung sites, New York). Similar macrofossil condition and twig morphology among samples, but difference from a modern boreal fen analog, confirmed the deposits were digesta. Comparison of twigs with material from other paleontological sites and modern elephants suggested dimensions generally indicative of digesta. Picea formed the bulk of each sample but Pinus may have been locally important. Wintertime browsing of Salix and Populus, and springtime consumption of Alnus, were indicated. Evidence for Cyperaceae, Gramineae, and Compositae was ambiguous. If conifers, broadleaf trees, shrubs, and herbs were necessary to fulfill dietary requirements, mastodons would have been nutritionally stressed by rapid late-Pleistocene decrease in vegetational diversity.

  4. Satellite chlorophyll fluorescence measurements reveal large-scale decoupling of photosynthesis and greenness dynamics in boreal evergreen forests.

    Science.gov (United States)

    Walther, Sophia; Voigt, Maximilian; Thum, Tea; Gonsamo, Alemu; Zhang, Yongguang; Köhler, Philipp; Jung, Martin; Varlagin, Andrej; Guanter, Luis

    2016-09-01

    Mid-to-high latitude forests play an important role in the terrestrial carbon cycle, but the representation of photosynthesis in boreal forests by current modelling and observational methods is still challenging. In particular, the applicability of existing satellite-based proxies of greenness to indicate photosynthetic activity is hindered by small annual changes in green biomass of the often evergreen tree population and by the confounding effects of background materials such as snow. As an alternative, satellite measurements of sun-induced chlorophyll fluorescence (SIF) can be used as a direct proxy of photosynthetic activity. In this study, the start and end of the photosynthetically active season of the main boreal forests are analysed using spaceborne SIF measurements retrieved from the GOME-2 instrument and compared to that of green biomass, proxied by vegetation indices including the Enhanced Vegetation Index (EVI) derived from MODIS data. We find that photosynthesis and greenness show a similar seasonality in deciduous forests. In high-latitude evergreen needleleaf forests, however, the length of the photosynthetically active period indicated by SIF is up to 6 weeks longer than the green biomass changing period proxied by EVI, with SIF showing a start-of-season of approximately 1 month earlier than EVI. On average, the photosynthetic spring recovery as signalled by SIF occurs as soon as air temperatures exceed the freezing point (2-3 °C) and when the snow on the ground has not yet completely melted. These findings are supported by model data of gross primary production and a number of other studies which evaluated in situ observations of CO2 fluxes, meteorology and the physiological state of the needles. Our results demonstrate the sensitivity of space-based SIF measurements to light-use efficiency of boreal forests and their potential for an unbiased detection of photosynthetic activity even under the challenging conditions interposed by evergreen

  5. Observation and modelling of HOx radicals in a boreal forest

    Science.gov (United States)

    Hens, K.; Novelli, A.; Martinez, M.; Auld, J.; Axinte, R.; Bohn, B.; Fischer, H.; Keronen, P.; Kubistin, D.; Nölscher, A. C.; Oswald, R.; Paasonen, P.; Petäjä, T.; Regelin, E.; Sander, R.; Sinha, V.; Sipilä, M.; Taraborrelli, D.; Tatum Ernest, C.; Williams, J.; Lelieveld, J.; Harder, H.

    2014-08-01

    Measurements of OH and HO2 radicals were conducted in a pine-dominated forest in southern Finland during the HUMPPA-COPEC-2010 (Hyytiälä United Measurements of Photochemistry and Particles in Air - Comprehensive Organic Precursor Emission and Concentration study) field campaign in summer 2010. Simultaneous side-by-side measurements of hydroxyl radicals were conducted with two instruments using chemical ionization mass spectrometry (CIMS) and laser-induced fluorescence (LIF), indicating small systematic disagreement, OHLIF / OHCIMS = (1.31 ± 0.14). Subsequently, the LIF instrument was moved to the top of a 20 m tower, just above the canopy, to investigate the radical chemistry at the ecosystem-atmosphere interface. Comprehensive measurements including observations of many volatile organic compounds (VOCs) and the total OH reactivity were conducted and analysed using steady-state calculations as well as an observationally constrained box model. Production rates of OH calculated from measured OH precursors are consistent with those derived from the steady-state assumption and measured total OH loss under conditions of moderate OH reactivity. The primary photolytic sources of OH contribute up to one-third to the total OH production. OH recycling, which occurs mainly by HO2 reacting with NO and O3, dominates the total hydroxyl radical production in this boreal forest. Box model simulations agree with measurements for hydroxyl radicals (OHmod. / OHobs. = 1.00 ± 0.16), while HO2 mixing ratios are significantly under-predicted (HO2mod. / HO2obs. = 0.3 ± 0.2), and simulated OH reactivity does not match the observed OH reactivity. The simultaneous under-prediction of HO2 and OH reactivity in periods in which OH concentrations were simulated realistically suggests that the missing OH reactivity is an unaccounted-for source of HO2. Detailed analysis of the HOx production, loss, and recycling pathways suggests that in periods of high total OH reactivity there are

  6. Observation and modelling of HOx radicals in a boreal forest

    Directory of Open Access Journals (Sweden)

    K. Hens

    2014-08-01

    Full Text Available Measurements of OH and HO2 radicals were conducted in a pine-dominated forest in southern Finland during the HUMPPA-COPEC-2010 (Hyytiälä United Measurements of Photochemistry and Particles in Air – Comprehensive Organic Precursor Emission and Concentration study field campaign in summer 2010. Simultaneous side-by-side measurements of hydroxyl radicals were conducted with two instruments using chemical ionization mass spectrometry (CIMS and laser-induced fluorescence (LIF, indicating small systematic disagreement, OHLIF / OHCIMS = (1.31 ± 0.14. Subsequently, the LIF instrument was moved to the top of a 20 m tower, just above the canopy, to investigate the radical chemistry at the ecosystem–atmosphere interface. Comprehensive measurements including observations of many volatile organic compounds (VOCs and the total OH reactivity were conducted and analysed using steady-state calculations as well as an observationally constrained box model. Production rates of OH calculated from measured OH precursors are consistent with those derived from the steady-state assumption and measured total OH loss under conditions of moderate OH reactivity. The primary photolytic sources of OH contribute up to one-third to the total OH production. OH recycling, which occurs mainly by HO2 reacting with NO and O3, dominates the total hydroxyl radical production in this boreal forest. Box model simulations agree with measurements for hydroxyl radicals (OHmod. / OHobs. = 1.00 ± 0.16, while HO2 mixing ratios are significantly under-predicted (HO2mod. / HO2obs. = 0.3 ± 0.2, and simulated OH reactivity does not match the observed OH reactivity. The simultaneous under-prediction of HO2 and OH reactivity in periods in which OH concentrations were simulated realistically suggests that the missing OH reactivity is an unaccounted-for source of HO2. Detailed analysis of the HOx production, loss, and recycling pathways suggests that in periods of high total OH reactivity

  7. Physiological response in the European flounder (Platichthys flesus) to variable salinity and oxygen conditions

    DEFF Research Database (Denmark)

    Lundgreen, Kim; Kiilerich, Pia; Tipsmark, Christian Kølbæk;

    2008-01-01

    (water Po2 = 158 mmHg) and then subjected to 48 h of continued normoxia or hypoxia at a level (Po2 = 54 mmHg) close to but above the critical Po2. Plasma osmolality, [Na+] and [Cl-] increased with increasing salinity, but the rises were limited, reflecting an effective extracellular osmoregulation......Physiological mechanisms involved in acclimation to variable salinity and oxygen levels and their interaction were studied in European flounder. The fish were acclimated for two weeks to freshwater (1 ‰ salinity), brackish water (11 ‰) or full strength seawater (35 ‰) under normoxic conditions...... erythrocytic nucleoside triphosphate content, a common mechanism for increasing blood O2 affinity. It is concluded that moderate hypoxia induced an energy saving decrease in branchial Na+/K+-ATPase activity, which did not compromise extracellular osmoregulation....

  8. Who is the new sheriff in town regulating boreal forest growth?

    Science.gov (United States)

    Park Williams, A.; Xu, Chonggang; McDowell, Nate G.

    2011-12-01

    the wettest 20 sites (green line), 19 sites with intermediate annual precipitation (black line) and the driest 20 sites (brown line). Error bars in (a)-(c) are standard errors. Perhaps an even bigger mystery is what the future has in store at the cold ecotone where boreal forest gives way to arctic tundra. Just as for warmer sites, there tends to be a temperature threshold at cold and intermediate sites, above which further warming no longer positively influences growth rate (figures 1(a) and (b)). Rather than reverse sign once this threshold is surpassed, growth-temperature relationships at cold and intermediate sites tend to simply disappear or at least diminish. This is because metabolic rates are slow in the cold, but are optimal under moderately warmer conditions (Tjoelker et al 2009). As temperature increases into a range of variability that no longer limits metabolic rate, a host of other climatic and soil-related factors can limit or promote growth and seedling recruitment. At some cool treeline sites, rapidly rising temperatures may have already surpassed the level that supports optimal growth, as negative relationships have emerged between temperature and growth rate in most decades (McGuire et al 2010). In a recent contribution to this important body of research, Andreu-Hayles et al (2011) studied growth-temperature relations within a white spruce population growing at the northern treeline in Alaska. Consistent with observations elsewhere in boreal forests, Andreu-Hayles et al discovered that a positive and significant relationship between ring widths and June-July temperature during 1901-1950 disappeared during 1951-2000. Interestingly, ring widths and temperature both increased throughout the 20th century at this treeline site, in contrast to recent trends at many other sites in Alaska where warming is outpacing ring widths (e.g., D'Arrigo et al 2008). At the site studied by Andreu-Hayles et al, it seems recent warming has caused a release of white

  9. Carbonaceous aerosols from prescribed burning of a boreal forest ecosystem. Revision

    Energy Technology Data Exchange (ETDEWEB)

    Mazurek, M.A. [Brookhaven National Lab., Upton, NY (United States); Cofer, W.R. III; Levine, J.S. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center

    1990-10-01

    The identity and ambient mass concentrations of radiatively important carbonaceous aerosols were measured for a boreal forest prescribed burn conducted in northern Ontario, CAN in August 1989. Nonsize-segregated airborne particles were collected for smoldering-fire and full-fire conditions using a helicopter sampling platform. Total carbon (TC), organic carbon (OC) and elemental carbon (EC) were measured. Smoke plume mass concentrations of the OC and EC particles were greatest for full-fire conditions and had ranges of 1.560 to 2.160 mg/m{sup {minus}1} (OC) and 0.120 to 0.160 mg/m{sup {minus}3} (EC) with OC:EC ratios of 10 to 18, respectively. Smoldering fire conditions showed smoke plume OC and EC levels of 0.570--1.030 mg/m{sup {minus}3} (OC) and 0.006--0.050 mg/m{sup {minus}3} (EC) and much higher ratios of OC:EC (21 to 95). These aerosol data indicate the formation of EC particles is greatest during full-fire combustion of boreal forest material relative to smoldering combustion. However, EC particles comprise a minor fraction of the particulate carbon smoke aerosols for both full-fire and smoldering conditions; the major component of carbonaceous smoke aerosols emitted during the prescribed burn is OC. Overall, the OC and EC in-plume smoke aerosol data show nonuniform production of these particles during various stages of the prescribed burn, and major differences in the type of carbonaceous aerosol that is generated (OC versus EC).

  10. Frost-ring chronologies as dendroclimatic proxies of boreal environments

    Science.gov (United States)

    Payette, Serge; Delwaide, Ann; Simard, Martin

    2010-01-01

    Frost rings are formed in tree stems when growing-season frosts affect immature wood cells, producing collapsed cells within annual tree rings. Open boreal forests are most susceptible to record growing-season frost because they lack the greenhouse effect commonly observed in closed forests. Here we present a novel method to construct regional frost-ring chronologies in lichen-black spruce woodlands of the boreal forest zone. Because the ability of trees to form frost rings depends on several factors (including bark thickness and ring width), we used two models to produce a Frost Composite Index based on a frost susceptibility window of cambial age growing-season frost activity may be used as dendroclimatic proxies of climate variability and may give insights into future risks of frost damage in a warming climate.

  11. Boreal ecosystems and landscapes: structures, processes and conservation of biodiversity

    International Nuclear Information System (INIS)

    This is a scientific summation of a research program on 'Remnant habitats in production landscapes' that was initiated and supported by the Swedish Environmental Protection Agency (SEPA). Ideas on conservation research and some preliminary results from this program were earlier published as the book 'Ecological principles of nature conservation. Applications in temperate and boreal environments'. The various projects in the total research program have now been implemented and completed and primary results have been published in international journals on ecology and conservation. Here we try to synthesize the data from various aspects and try to deduce suitable conservation management for boreal ecosystems and landscapes. Ecologists from outside the program but with similar scientific background and approaches have also been involved as authors. A number of original ideas discussed in the first book have been retained here in order to make our approaches and findings easily understandable. (EG)

  12. Recent burning of boreal forests exceeds fire regime limits of the past 10,000 years

    OpenAIRE

    Kelly, Ryan; Chipman, Melissa L.; Philip E Higuera; Stefanova, Ivanka; Brubaker, Linda B.; Hu, Feng Sheng

    2013-01-01

    Wildfire activity in boreal forests is anticipated to increase dramatically, with far-reaching ecological and socioeconomic consequences. Paleorecords are indispensible for elucidating boreal fire regime dynamics under changing climate, because fire return intervals and successional cycles in these ecosystems occur over decadal to centennial timescales. We present charcoal records from 14 lakes in the Yukon Flats of interior Alaska, one of the most flammable ecoregions of the boreal forest bi...

  13. Monitoring forest cover change in boreal forests: a methodological approach

    OpenAIRE

    KISSIYAR Ouns; BARTALEV SVYATOSLAV; ACHARD Frederic

    2014-01-01

    The purpose of this study is to develop a monitoring tool for boreal forest cover change on continental level at high resolution. The system is based on Landsat satellite imagery and has been implemented for the period 1990-2000-2010. For the identification and classification of the forest cover within a large amount of satellite imagery, a robust methodological approach combining multi-date image segmentation and cluster based supervised automated classification was chosen. Thus, an object b...

  14. Forest edges in boreal landscapes - factors affecting edge influence

    OpenAIRE

    Jansson, Ulrika

    2009-01-01

    The boreal forest in Fennoscandia has been subjected to major loss and fragmentation of natural forests due to intensive forestry. This has resulted in that forest edges are now abundant and important landscape features. Edges have documented effects on the structure, function and biodiversity in forests. Edge influence on biodiversity is complex and depends on interactions between many local and regional factors. This thesis focuses on sharp forest edges and their potential to influence biod...

  15. Boreal forest albedo and its spatial and temporal variation

    OpenAIRE

    Kuusinen, Nea

    2014-01-01

    Surface albedo refers to the fraction of solar irradiance that is reflected by a surface. Accurate characterisation of the albedo of various land cover types is required for evaluating the energy exchange between the Earth s surface and the atmosphere. The optical and structural properties of a surface determine its albedo. Boreal forest albedo can vary due to factors such as tree species composition, forest structure, understorey vegetation composition, and seasonal changes in vegetation and...

  16. Forest landscape change in boreal Sweden 1850-2000

    OpenAIRE

    Axelsson, Anna-Lena

    2001-01-01

    In the project described in this thesis, structural changes that have occurred in the boreal Swedish forest during the last 150 years were studied through analysis of historical records. Historical perspectives on forest landscapes provide a better understanding of natural disturbance dynamics as well as anthropogenic changes and a frame of reference for assessing current ecological patterns and processes. The studies were performed at various spatial scales, and were conducted in two differe...

  17. Photosynthesis of ground vegetation in boreal Scots pine forests

    OpenAIRE

    Kulmala, Liisa

    2011-01-01

    Research on carbon uptake in boreal forests has mainly focused on mature trees, even though ground vegetation species are effective assimilators and can substantially contribute to the CO2 uptake of forests. Here, I examine the photosynthesis of the most common species of ground vegetation in a series of differently aged Scots pine stands, and at two clear-cut sites with substantial differences in fertility. In general, the biomass of evergreen species was highest at poor sites and below cano...

  18. Recreation and tourism induced changes in northern boreal environments

    OpenAIRE

    Kangas, K. (Katja)

    2009-01-01

    Abstract The popularity of nature-based tourism has increased worldwide and peripheral areas with conservational value, like protected areas, are attractive destinations. The recreational use and construction of tourism facilities can cause environmental degradation and decrease the conservational and recreational value of areas if not well planned and managed. The aim of this thesis was to improve our knowledge of recreation and tourism induced changes in northern boreal environments. Dir...

  19. The fate of airborne lead pollution in boreal forest soils

    OpenAIRE

    Klaminder, Jonatan

    2005-01-01

    Lead has a more than three-millennia-long pollution history in Europe. Metal production, burning of coal and use of leaded petrol resulted in a significant pollution of the atmosphere. As a consequence of atmospheric fallout, the Swedish boreal forest is strongly contaminated by airborne lead pollution. High levels of lead in the soil and soil pore water are of concern because the soil fauna, plants and aquatic biota may respond negatively to this toxic element. The fate of the accumulated po...

  20. Aquatic ecosystem responses to Holocene climate change and biome development in boreal, central Asia

    Science.gov (United States)

    Mackay, Anson W.; Bezrukova, Elena V.; Leng, Melanie J.; Meaney, Miriam; Nunes, Ana; Piotrowska, Natalia; Self, Angela; Shchetnikov, Alexander; Shilland, Ewan; Tarasov, Pavel; Wang, Luo; White, Dustin

    2012-05-01

    Boreal ecosystems are highly vulnerable to climate change, and severe ecological impacts in the near future are virtually certain to occur. We undertook a multiproxy study on an alpine lake (ESM-1) at the modern tree-line in boreal, southern Siberia. Steppe and tundra biomes were extensive in eastern Sayan landscapes during the early Holocene. Boreal forest quickly expanded by 9.1 ka BP, and dominated the landscape until c 0.7 ka BP, when the greatest period of compositional turnover occurred. At this time, alpine meadow landscape expanded and Picea obovata colonised new habitats along river valleys and lake shorelines, because of prevailing cool, moist conditions. During the early Holocene, chironomid assemblages were dominated by cold stenotherms. Diatoms for much of the Holocene were dominated by alkaliphilous, fragilarioid taxa, up until 0.2 ka BP, when epiphytic species expanded, indicative of increased habitat availability. C/N mass ratios ranged between 9.5 and 13.5 (11.1-15.8 C/N atomic ratios), indicative of algal communities dominating organic matter contributions to bottom sediments with small, persistent contributions from vascular plants. However, δ13C values increased steadily from -34.9‰ during the early Holocene (9.3 ka BP) to -24.8‰ by 0.6 ka BP. This large shift in magnitude may be due to a number of factors, including increasing within-lake productivity, increasing disequilibrium between the isotopic balance of the lake with the atmosphere as the lake became isotopically ‘mature’, and declining soil respiration linked to small, but distinct retreat in forest biomes. The influence of climatic variables on landscape vegetation was assessed using redundancy analysis (RDA), a linear, direct ordination technique. Changes in July insolation at 60 °N significantly explained over one-fifth of the variation in species composition, while changes in estimates of northern hemisphere temperature and ice-rafted debris events in the North Atlantic

  1. Predicting Climate Change Impacts to the Canadian Boreal Forest

    Directory of Open Access Journals (Sweden)

    Trisalyn A. Nelson

    2014-03-01

    Full Text Available Climate change is expected to alter temperature, precipitation, and seasonality with potentially acute impacts on Canada’s boreal. In this research we predicted future spatial distributions of biodiversity in Canada’s boreal for 2020, 2050, and 2080 using indirect indicators derived from remote sensing and based on vegetation productivity. Vegetation productivity indices, representing annual amounts and variability of greenness, have been shown to relate to tree and wildlife richness in Canada’s boreal. Relationships between historical satellite-derived productivity and climate data were applied to modelled scenarios of future climate to predict and map potential future vegetation productivity for 592 regions across Canada. Results indicated that the pattern of vegetation productivity will become more homogenous, particularly west of Hudson Bay. We expect climate change to impact biodiversity along north/south gradients and by 2080 vegetation distributions will be dominated by processes of seasonality in the north and a combination of cumulative greenness and minimum cover in the south. The Hudson Plains, which host the world’s largest and most contiguous wetland, are predicted to experience less seasonality and more greenness. The spatial distribution of predicted trends in vegetation productivity was emphasized over absolute values, in order to support regional biodiversity assessments and conservation planning.

  2. Carbon balance and climate change in boreal forests

    Energy Technology Data Exchange (ETDEWEB)

    Bhatti, J. S.; Laird, L. D.; Banfield, E. [Canadian Forest Service, Northern Forestry Centre, Edmonton, AB (Canada); Van Kooten, G. C. [Victoria Univ., Dept. of Economics, Victoria, BC (Canada); Apps, M. J. [Canadian Forest Service, Pacific Forestry Centre, Victoria, BC (Canada); Campbell, I. D. [Natural Resources Canada, Geological Survey of Canada, Ottawa, ON (Canada); Campbell, C. [Canadian Forest Service, Ottawa, ON (Canada); Turetsky, M. R. [U. S. Geological Survey, Western Region Center, Menlo Park, CA (United States); Yu, Z. [Lehigh Univ., Earth and Environmental Sciences, Bethlehem, PA (United States)

    2003-07-01

    Carbon is exchanged between terrestrial ecosystems and the atmosphere through photosynthesis, respiration, decomposition, and combustion, hence its importance to global climate. To explain that role, this chapter discusses the role of the boreal forest in the carbon cycle, the expected impacts of climate change on the boreal ecosystem, and the effects of various natural and human factors on the carbon balance of the forest. Economic and forest management issues in relation to carbon resources of the forest are also explored in light of the Kyoto Protocol commitments to reduce greenhouse gas emissions, along with challenges to sustainable forest management seen from the vantage point of climatic change. Among natural disasters, fire, infestation by insects and pathogens,storms, floods, and landslides receive attention, whereas in the area of human impacts attention is focused on land-use practices, and forest stand and landscape-level management. An overview of the Kyoto Protocol, Canada's commitments, the concepts of emissions trading, and carbon credits and the role of forestry, is provided. Other subjects explored include options for minimizing carbon emission in boreal forestry, and the economic impacts of adaptation to climate change on forestry. 245 refs., 5 tabs., 13 figs.

  3. Struvite crystallization under a marine/brackish aquaculture condition.

    Science.gov (United States)

    Zhang, Xuedong; Hu, Jianmei; Spanjers, Henri; van Lier, Jules B

    2016-10-01

    The results in this study show that struvite was formed in the digester at pH 7.7 due to the magnesium naturally present and the released ammonia and phosphate, resulting in low phosphate concentration in the digester. Apparently the digester already provided proper conditions for struvite formation. Under the brackish condition, the estimated thermodynamic solubility product and enthalpy change of struvite formation were 10(-13.06) and 25.7kJmol(-1), respectively. The average crystal size under marine/brackish condition decreased with pH, but increased with temperature. X-ray diffraction measurements indicate struvite (NH4MgPO4·6H2O) and dittmarite (NH4MgPO4·H2O) were predominant phosphorus species produced in filtrates of the digester. However, struvite and newberyite (HMgPO4·3H2O) were the predominant species precipitated from synthetic brackish waters after dosing MgCl2. It is pronounced that (waste)water characteristics played also an important role on the nature of phosphate precipitates. Under high NH4(+) condition, phosphorus precipitates containing ammonia were dominant, compared to other amorphous phosphates. PMID:27469096

  4. Changing Boreal Fire Regimes: Impacts on Permafrost Soils and Forest Succession in Siberian Larch Forests

    Science.gov (United States)

    Alexander, H. D.; Mack, M. C.; Natali, S.; Loranty, M. M.; Davydov, S. P.; Zimov, N.

    2014-12-01

    Fire activity has increased across the boreal forest biome in conjuction with climate warming and drying. Because these forests contain a large proportion of global terrestrial carbon (C) stocks, there has been great interest in understanding feedbacks between a changing fire regime and climate warming. An important mechanism by which increased fire activity may alter boreal C balance is by consuming the soil organic layer (SOL). Fire removal of the SOL may alter germination microsites and tree recruitment, thereby altering forest successional trajectories and C accumulation and storage. In permafrost soils, loss of the insulating SOL can increase soil temperature and active layer depth, impacting growth and survival conditions for both soil microbes and vegetation. To assess fire severity effects on permafrost soils and tree recruitment, we conducted plot-level experimental burns in July 2012 in a larch forest near Cherskii, Siberia. We achieved four burn severity treatments based on residual SOL depths: control, low (> 8 cm), moderate (5-8 cm), and high severity (2-5 cm). For two growing seasons post-fire, we measured thaw depth, soil moisture, and soil temperature. We sowed larch seeds in fall 2012 and 2013 and quantified seedling establishment and vegetation re-growth for two growing seasons. Immediately post-fire, thaw depth increased rapidly with increasing fire severity, and this trend has persisted for two years. In 2013 and 2014, thaw depth was ~ 40 cm deeper in high severity plots compared to controls, likely due to lower summer soil insulation, higher black char cover, and higher surface soil temperatures. We observed little to no larch recruitment in unburned and low severity plots, but new seedling density was ~5 seedlings m-2 in moderate and high severity plots, which had low cover of other vegetation types and high soil moisture. Findings suggest that increased fire severity may increase larch recruitment and provide favorable soil conditions for

  5. Threshold responses in regional runoff from a heterogeneous low relief terrain - Western Canada's Boreal Plains

    Science.gov (United States)

    Devito, Kevin; Anderson, Axel; Kettridge, Nick; Mendoza, Carl; Petrone, Rich; Silins, Uldis; Smith, Kevin; Waddington, Mike

    2014-05-01

    Runoff from larger catchments (>1000km) in the continental Boreal Plains (BP) eco-region of Western Canada, although low, can range over 3 orders of magnitude (4 mm to 350 mm/yr) among years and be difficult to predict. This region of western Canada is experiencing unprecedentedly rapid and large-scale industrial development. There is a need to assess and understand the dominant controls on the temporal and spatial threshold responses of regional runoff generation to be able to predict and mitigate the potential impacts of land use and effectiveness of reclamation practices on surface water quantity and quality. The Boreal Plain climate has regional moisture deficit (Pdeciduous and conifers forests, with some areas greater that 50 % of the surface is covered be wetlands ecosystems, mostly peatland.. Process based and experimental studies of forest-wetland hydrologic linkages show that at the local scale forested areas infrequently generate runoff because of high storage capability of the deep soils and effective transpiration capabilities of the trees. This contrasts wetlands that saturate readily due to lower soil storage capabilities and less effective evaporative processes, which results in persistent lateral surface or near surface runoff from wetland complexes. We examine the interaction among the wetland and forest HUs, the glacial landforms HRAs and decadal climate cycles on the threshold response of regional runoff in a range of catchments (50 ha to 50000 km2) from the Boral Plain of Alberta. Annual runoff (mm) and efficiency (RC) were poorly correlated with annual precipitation, but showed a strong threshold relationship with multi-year cumulative moisture deficit (CMD). Changes in precipitation patterns result in decadal cycles of dry (CMD 200 mm) states occurring every 2-3 decades. The differing CMD states altered the hydrologic connectivity among different portions of HRA's and HUs within catchments. During dry states base flow conditions ranged by over

  6. The hydrological effects of harvesting at Boreal Plain, Alberta

    Science.gov (United States)

    Kiyani, Ghasemali; Yew Gan, Thian; Devito, Kevin

    2010-05-01

    Unique hydrological characteristics of Boreal Plain environment such as sub-humid climate, deep glacial deposits, and significant heterogeneity in soil and vegetation type creates a complicated hydrology in the region. The study of hydrological effects of harvesting in Boreal Plain, which is occurring at an unprecedented rate for oil and gas exploration and timber harvesting, is necessary for a sustainable forest management. However there are a few previous studies addressing the hydrological effects of harvesting on quantity and quality of water in Boreal Plain. This paper reports on an on-going paired catchments experimental study at Alpac Catchment Experiment (ACE: 55N 112W) area near Lac La Biche, Alberta started in early 2005. A 2-km2 catchment (H2) was harvested almost 70% in winter 2006. Later, the harvesting occurred sequentially within the bigger catchment (H1, 10 km2) i.e. 29% in 2007 and 19% in 2008 totally account for about 80% of aspen forest. Finally, the smallest catchments was harvested approximately 90% in summer 2008. The collected pre- and post harvest data have been used to assess the effect of harvesting on the catchment overall responses and soil moisture. The pre-harvest streamflow data collected at H1 and its reference catchment R1 show that unit area runoff of both catchments are matched fairly good, and may be used to assess changes in streamflow after harvesting. An increase in soil moisture and soil temperature after harvesting was observed in H2, but little to no change in streamflow response. This suggests the dominance of soil moisture in the catchment, which might be a promising indicator for tracking the effect of harvesting. The field data is then used to drive the hydrological model MISBA to simulate the water and energy cycling in the Boreal Plain. By adding a reservoir to MISBA to simulate the significant soil storage characteristic of the Boreal Plain, and by applying different catchment discretization schemes based on soil

  7. Nitrogen balance along a boreal forest fire chronosequence

    Science.gov (United States)

    Palviainen, Marjo; Pumpanen, Jukka; Berninger, Frank; Heinonsalo, Jussi; Sun, Hui; Köster, Egle; Köster, Kajar

    2016-04-01

    Fire is a major natural disturbance factor in boreal forests, and the frequency of forest fires is predicted to increase due to climate change in boreal regions. Because boreal forests comprise 30% of the global forest area, increases in the annual area burned may have significant implications for global carbon and nitrogen (N) cycles. The productivity of boreal forests is limited by low N availability. Fires cause N loss from ecosystems through oxidation and volatilization of N stored in biomass and soil. N balance may be poorly buffered against forest fires especially in sub-arctic ecosystems where atmospheric N deposition is low. Although forest fires alter N dynamics, there are little quantitative data available on N pools and fluxes through post-fire succession in sub-arctic boreal forests. We studied changes in N pools and fluxes, and the overall N balance across a 155-year forest fire chronosequence in sub-arctic Scots pine (Pinus sylvestris) forests in Värriö Strict Nature Reserve situated in Finnish Lapland (67°46' N, 29°35' E). Soil was the largest N pool in all forest age classes and comprised 69-82% of the total ecosystem N pool. The total ecosystem N pool varied from 622 kg ha-1 in the recently burned forest to 960 kg ha-1 in the 155-year-old forest. The forests were N sinks in all age classes the annual N accumulation rate being 2.28 kg ha-1 yr-1 which was distributed almost equally between soil and biomass. The observed changes in ecosystem N pools were consistent with the computed N balance 2.10 kg ha-1 yr-1 over the 155-year post-fire period (Balance= (atmospheric deposition + N fixation) - (leaching + N2O emissions)). The results indicated that N deposition is an important component of the N balance and the N outputs are small (13% of the inputs) in the studied ecosystems. N2O fluxes were negligible (≤ 0.01 kg ha-1 yr-1) compared to the other N fluxes. The biological N fixation increased with succession and constituted 9% of the total N

  8. Fire impacts on European Boreal soils: A review

    Science.gov (United States)

    Pereira, Paulo; Oliva, Marc; Cerda, Artemi

    2016-04-01

    Fire is an important natural disturbance in boreal ecosystems, fundamental to understand plant distribution (Ryan, 2002; Wallenius et al., 2004; Granstrom, 2001). Nevertheless, nowadays the intense and successful, fire suppression measures are changing their ecological role (Pereira et al., 2013a,b). This is consequence of the lack of understanding of stakeholders and decision makers about the role of the fire in the ecosystems (Mierasukas and Pereira, 2013; Pereira et al., 2016). This fire suppression measures are increasing the amount of fuel accumulation and the risk of severe wildfires, which can increase of frequency and severity in a context of climate change. Fire is a good tool for landscape management and restoration of degraded ecosystems (Toivanen and Kotiaho, 2007). Fire is considered a soil forming factor (Certini, 2014) and in boreal environments it has been observed that low fire severities, do not change importantly soil properties, mean fire severities induce positive impacts on soil, since add an important amounts of nutrients into soil profile and high severity fires had negative impacts due to the high consumption of organic matter (Vanha-Majamaa et al., 2007; Pereira et al., 2014). References Certini, G., 2014. Fire as a soil-forming factor. Ambio, 43, 191-195 Granstrom A. 2001. Fire management for biodiversity in the European Boreal forest. Scandinavian Journal of Forest Research 3: 62-69. Mierauskas, P., Pereira, P. (2013) Stakeholders perception about prescribed fire use in Lithuania. First results, Flamma, 4(3), 157-161. Pereira, P., Cerdà, A., Jordán, A., Bolutiene, V., Úbeda, X., Pranskevicius, M., Mataix-Solera, J. (2013) Spatio-temporal vegetation recuperation after a grassland fire in Lithuania, Procedia Environmental Sciences, 19:856-864 Pereira, P., Mierauskas, P., Ubeda, X., Mataix-Solera, J.,Cerda, A. (2012) Fire in protected areas - the effect of the protection and importance of fire management, Environmental Research

  9. Tree Water Use May Significantly Impact Boreal Hydrology

    Science.gov (United States)

    Young, J. M.; Bolton, W. R.

    2013-12-01

    The ecohydrology of boreal forest ecosystems of Interior Alaska is not well understood largely because of challenges posed by the presence of discontinuous permafrost. Near-surface permafrost results in storage-dominated systems with cold, poorly drained soils, and slow growing, low statured coniferous trees (Picea mariana) or CDE's. The transition to permafrost-free areas can occur over a few meters and is accompanied by a vegetation community dominated by large deciduous trees (Populus sp. and Betula sp.) or DDE's. Typically, areas with permafrost are on north facing slopes and valley bottoms, and areas without permafrost are south facing. In Alaska's boreal forest, the permafrost is very warm and vulnerable to the effects of climate change. Once permafrost begins to thaw, the vegetation community shifts from coniferous to deciduous dominated. Streamflow in watersheds with a larger permafrost distribution tends to be higher and more responsive to precipitation events than in watersheds with low permafrost distribution. In fact, precipitation events in the low permafrost areas do not infiltrate past the rooting zone of the deciduous trees (~5-40 cm). This suggests that the deciduous trees may remove water from the system via uptake and transpiration. We focus on how vegetation water use affects boreal forest hydrology in areas of discontinuous permafrost. Specifically, we ask: what are the patterns of vegetation water use in areas with and without permafrost? This study focuses on the CDE and DDE systems. Our research sites are established on low and high locations on each aspect (south facing DDE, north facing CDE) to capture the variability associated with the different hillside drainage properties. At each of the four sites during the growing season, we measured various aspects of plant water use dynamics, including water flux, water content, water sources, depth of water uptake in the soil, and water stress. We use a Bayesian framework to analyze the data. We

  10. Functional Diversity of Boreal Bog Plant Species Decreases Seasonal Variation of Ecosystem Carbon Sink Function

    Science.gov (United States)

    Korrensalo, A.

    2015-12-01

    Species diversity has been found to decrease the temporal variance of productivity of a plant community, and diversity in species responses to environmental factors seems to make a plant community more stable in changing conditions. Boreal bogs are nutrient poor peatland ecosystems where the number of plant species is low but the species differ greatly in their growth form. In here we aim to assess the role of the variation in photosynthesis between species for the temporal variation in ecosystem carbon sink function. To quantify the photosynthetic properties and their seasonal variation for different bog plant species we measured photosynthetic parameters and stress-inducing chlorophyll fluorescence of vascular plant and Sphagnum moss species in a boreal bog over a growing season. We estimated monthly gross photosynthesis (PG) of the whole study site based on species level light response curves and leaf area development. The estimated PG was further compared with a gross primary production (GPP) estimate measured by eddy covariance (EC) technique. The sum of upscaled PG estimates agreed well with the GPP estimate measured by the EC technique. The contributions of the species and species groups to the ecosystem level PG changed over the growing season. The sharp mid-summer peak in sedge PG was balanced by more stable PG of evergreen shrubs and Sphagna. Species abundance rather than differences in photosynthetic properties between species and growth forms determined the most productive plants on the ecosystem scale. Sphagna had lower photosynthesis and clorophyll fluorescence than vascular plants but were more productive on the ecosystem scale throughout the growing season due to their high areal coverage. These results show that the diversity of growth forms stabilizes the seasonal variation of the ecosystem level PG in an ombrotrophic bog ecosystem. This may increase the resilience of the ecosystem to changing environmental conditions.

  11. New datasets for quantifying snow-vegetation-atmosphere interactions in boreal birch and conifer forests

    Science.gov (United States)

    Reid, T. D.; Essery, R.; Rutter, N.; Huntley, B.; Baxter, R.; Holden, R.; King, M.; Hancock, S.; Carle, J.

    2012-12-01

    Boreal forests exert a strong influence on weather and climate by modifying the surface energy and radiation balance. However, global climate and numerical weather prediction models use forest parameter values from simple look-up tables or maps that are derived from limited satellite data, on large grid scales. In reality, Arctic landscapes are inherently heterogeneous, with highly variable land cover types and structures on a variety of spatial scales. There is value in collecting detailed field data for different areas of vegetation cover, to assess the accuracy of large-scale assumptions. To address these issues, a consortium of researchers funded by the UK's Natural Environment Research Council have collected extensive data on radiation, meteorology, snow cover and canopy structure at two contrasting Arctic forest sites. The chosen study sites were an area of boreal birch forest near Abisko, Sweden in March/April 2011 and mixed conifer forest at Sodankylä, Finland in March/April 2012. At both sites, arrays comprising ten shortwave pyranometers and four longwave pyrgeometers were deployed for periods of up to 50 days, under forest plots of varying canopy structures and densities. In addition, downwelling longwave irradiance and global and diffuse shortwave irradiances were recorded at nearby open sites representing the top-of-canopy conditions. Meteorological data were recorded at all sub-canopy and open sites using automatic weather stations. Over the same periods, tree skin temperatures were measured on selected trees using contact thermocouples, infrared thermocouples and thermal imagery. Canopy structure was accurately quantified through manual surveys, extensive hemispherical photography and terrestrial laser scans of every study plot. Sub-canopy snow depth and snow water equivalent were measured on fine-scale grids at each study plot. Regular site maintenance ensured a high quality dataset covering the important Arctic spring period. The data have several

  12. Effects of warming on the structure and function of a boreal black spruce forest

    Energy Technology Data Exchange (ETDEWEB)

    Stith T.Gower

    2010-03-03

    A strong argument can be made that there is a greater need to study the effect of warming on boreal forests more than on any other terrestrial biome. Boreal forests, the second largest forest biome, are predicted to experience the greatest warming of any forest biome in the world, but a process-based understanding of how warming will affect the structure and function of this economically and ecologically important forest biome is lacking. The effects of warming on species composition, canopy structure and biogeochemical cycles are likely to be complex; elucidating the underlying mechanisms will require long-term whole-ecosystem manipulation to capture all the complex feedbacks (Shaver et al. 2000, Rustad et al. 2001, Stromgren 2001). The DOE Program for Ecosystem Research funded a three year project (2002-2005) to use replicated heated chambers on soil warming plots in northern Manitoba to examine the direct effects of whole-ecosystem warming. We are nearing completion of our first growing season of measurements (fall 2004). In spite of the unforeseen difficulty of installing the heating cable, our heating and irrigation systems worked extremely well, maintaining environmental conditions within 5-10% of the specified design 99% of the time. Preliminary data from these systems, all designed and built by our laboratory at the University of Wisconsin, support our overall hypothesis that warming will increase the carbon sink strength of upland boreal black spruce forests. I request an additional three years of funding to continue addressing the original objectives: (1) Examine the effect of warming on phenology of overstory, understory and bryophyte strata. Sap flux systems and dendrometer bands, monitored by data loggers, will be used to quantify changes in phenology and water use. (2) Quantify the effects of warming on nitrogen and water use by overstory, understory and bryophytes. (3) Compare effects of warming on autotrophic respiration and above- and belowground

  13. Production of peroxy nitrates in boreal biomass burning plumes over Canada during the BORTAS campaign

    Science.gov (United States)

    Busilacchio, Marcella; Di Carlo, Piero; Aruffo, Eleonora; Biancofiore, Fabio; Dari Salisburgo, Cesare; Giammaria, Franco; Bauguitte, Stephane; Lee, James; Moller, Sarah; Hopkins, James; Punjabi, Shalini; Andrews, Stephen; Lewis, Alistair C.; Parrington, Mark; Palmer, Paul I.; Hyer, Edward; Wolfe, Glenn M.

    2016-03-01

    PNs produced during biomass burning is significant in the O3 budget. The implication of these observations is that fire emissions in some cases, for example boreal forest fires and in the conditions reported here, may influence more long-lived precursors of O3 than short-lived pollutants, which in turn can be transported and eventually diluted in a wide area.

  14. Boreal summer continental monsoon rainfall and hydroclimate anomalies associated with the Asian-Pacific Oscillation

    Science.gov (United States)

    Zhao, Ping; Wang, Bin; Zhou, Xiuji

    2012-09-01

    With the twentieth century analysis data (1901-2002) for atmospheric circulation, precipitation, Palmer drought severity index, and sea surface temperature (SST), we show that the Asian-Pacific Oscillation (APO) during boreal summer is a major mode of the earth climate variation linking to global atmospheric circulation and hydroclimate anomalies, especially the Northern Hemisphere (NH) summer land monsoon. Associated with a positive APO phase are the warm troposphere over the Eurasian land and the relatively cool troposphere over the North Pacific, the North Atlantic, and the Indian Ocean. Such an amplified land-ocean thermal contrast between the Eurasian land and its adjacent oceans signifies a stronger than normal NH summer monsoon, with the strengthened southerly or southwesterly monsoon prevailing over tropical Africa, South Asia, and East Asia. A positive APO implies an enhanced summer monsoon rainfall over all major NH land monsoon regions: West Africa, South Asia, East Asia, and Mexico. Thus, APO is a sensible measure of the NH land monsoon rainfall intensity. Meanwhile, reduced precipitation appears over the arid and semiarid regions of northern Africa, the Middle East, and West Asia, manifesting the monsoon-desert coupling. On the other hand, surrounded by the cool troposphere over the North Pacific and North Atlantic, the extratropical North America has weakened low-level continental low and upper-level ridge, hence a deficient summer rainfall. Corresponding to a high APO index, the African and South Asian monsoon regions are wet and cool, the East Asian monsoon region is wet and hot, and the extratropical North America is dry and hot. Wet and dry climates correspond to wet and dry soil conditions, respectively. The APO is also associated with significant variations of SST in the entire Pacific and the extratropical North Atlantic during boreal summer, which resembles the Interdecadal Pacific Oscillation in SST. Of note is that the Pacific SST anomalies

  15. The summertime Boreal forest field measurement intensive (HUMPPA-COPEC-2010: an overview of meteorological and chemical influences

    Directory of Open Access Journals (Sweden)

    J. Williams

    2011-05-01

    Full Text Available This paper describes the background, instrumentation, goals, and the regional influences on the HUMPPA-COPEC intensive field measurement campaign, conducted at the Boreal forest research station SMEAR II (Station for Measuring Ecosystem-Atmosphere Relation in Hyytiälä, Finland from 12 July–12 August 2010. The prevailing meteorological conditions during the campaign are examined and contrasted with those of the past six years. Back trajectory analyses show that meteorological conditions at the site were characterized by a higher proportion of southerly flow. As a result the summer of 2010 was anomalously warm and high in ozone making the campaign relevant for the analysis of possible future climates. A comprehensive land use analysis, provided on both 5 and 50 km scales, shows that the main vegetation types surrounding the site on both the regional and local scales are: coniferous forest (Scots pine and/or Norway spruce; mixed forest (Birch and conifers; and woodland scrub (e.g. Willows, Aspen; indicating that the campaign results can be taken as representative of the Boreal forest ecosystem. In addition to the influence of biogenic emissions, the measurement site was occasionally impacted by sources other than vegetation. Specific tracers have been used here to identify the time periods when such sources have impacted the site namely: biomass burning (acetonitrile and CO, urban anthropogenic pollution (pentane and SO2 and the nearby Korkeakoski sawmill (enantiomeric ratio of chiral monoterpenes. None of these sources dominated the study period, allowing the Boreal forest summertime emissions to be assessed and contrasted with various other source signatures.

  16. The summertime Boreal forest field measurement intensive (HUMPPA-COPEC-2010: an overview of meteorological and chemical influences

    Directory of Open Access Journals (Sweden)

    J. Williams

    2011-10-01

    Full Text Available This paper describes the background, instrumentation, goals, and the regional influences on the HUMPPA-COPEC intensive field measurement campaign, conducted at the Boreal forest research station SMEAR II (Station for Measuring Ecosystem-Atmosphere Relation in Hyytiälä, Finland from 12 July–12 August 2010. The prevailing meteorological conditions during the campaign are examined and contrasted with those of the past six years. Back trajectory analyses show that meteorological conditions at the site in 2010 were characterized by a higher proportion of southerly flow than in the other years studied. As a result the summer of 2010 was anomalously warm and high in ozone making the campaign relevant for the analysis of possible future climates. A comprehensive land use analysis, provided on both 5 and 50 km scales, shows that the main vegetation types surrounding the site on both the regional and local scales are: coniferous forest (Scots pine and/or Norway spruce; mixed forest (Birch and conifers; and woodland scrub (e.g. Willows, Aspen; indicating that the campaign results can be taken as representative of the Boreal forest ecosystem. In addition to the influence of biogenic emissions, the measurement site was occasionally impacted by sources other than vegetation. Specific tracers have been used here to identify the time periods when such sources have impacted the site namely: biomass burning (acetonitrile and CO, urban anthropogenic pollution (pentane and SO2 and the nearby Korkeakoski sawmill (enantiomeric ratio of chiral monoterpenes. None of these sources dominated the study period, allowing the Boreal forest summertime emissions to be assessed and contrasted with various other source signatures.

  17. Fluxes of Dissolved Organic Carbon within Soils across a Boreal Forest Ecosystem Latitudinal Transect

    Science.gov (United States)

    Bowering, K.; Edwards, K.; Billings, S. A.; Skinner, A.; Warren, J.; Ziegler, S. E.

    2013-12-01

    The movement of dissolved organic carbon (DOC) can represent a significant flux of C within soils, and may be a critical flux of C from the terrestrial into the aquatic environment. Further, these fluxes can represent an important source of C to deeper mineral horizons where stabilization mechanisms may exist. However the quantity and quality of this C flux is largely unknown, and regulating factors that are influenced by climate and land-use change are poorly understood. This movement of C is of particular interest in the boreal forest, where large soil C stocks are vulnerable to the impacts of climate change. Laboratory experiments have demonstrated that warming, in the absence of moisture limitation, can increase the rate of production of DOC in soils directly through increased decomposition rates; however, this has been difficult to test under field conditions where seasonality, intact soil, and hydrological systems influence DOC production and movement. To assess the impact of climate warming on DOC fluxes occurring through the organic soil layer of the eastern North American boreal forest, we sampled passive lysimeters installed at 3 sites along a latitudinal transect in Newfoundland and Labrador, Canada. Separated by just over 5° latitude, mean annual temperature at these sites were 4°C, 2.1°C, and -0.5°C from lowest to highest latitude. Six lysimeters were sampled from each site and collections were made at least three times annually for two consecutive years (2011-2013). Soils tend to freeze over-winter in the high-latitude site whereas they rarely freeze in the low-latitude site. The low-latitude site also experiences more variable precipitation, with a longer snow-free season and more precipitation falling during single events. Rates of DOC flux increased with decreasing latitude, indicating greater DOC transport through soils in forests experiencing a warmer climate. DOC fluxes calculated over different seasonal time periods ranged from 4.6 to 20

  18. Methane emission modeling with MCMC calibration for a boreal peatland

    Science.gov (United States)

    Raivonen, Maarit; Smolander, Sampo; Susiluoto, Jouni; Backman, Leif; Li, Xuefei; Markkanen, Tiina; Kleinen, Thomas; Makela, Jarmo; Aalto, Tuula; Rinne, Janne; Brovkin, Victor; Vesala, Timo

    2016-04-01

    Natural wetlands, particularly peatlands of the boreal latitudes, are a significant source of methane (CH4). At the moment, the emission estimates are highly uncertain. These natural emissions respond to climatic variability, so it is necessary to understand their dynamics, in order to be able to predict how they affect the greenhouse gas balance in the future. We have developed a model of CH4 production, oxidation and transport in boreal peatlands. It simulates production of CH4 as a proportion of anaerobic peat respiration, transport of CH4 and oxygen between the soil and the atmosphere via diffusion in aerenchymatous plants and in peat pores (water and air filled), ebullition and oxidation of CH4 by methanotrophic microbes. Ultimately, we aim to add the model functionality to global climate models such as the JSBACH (Reick et al., 2013), the land surface scheme of the MPI Earth System Model. We tested the model with measured methane fluxes (using eddy covariance technique) from the Siikaneva site, an oligotrophic boreal fen in southern Finland (61°49' N, 24°11' E), over years 2005-2011. To give the model estimates regional reliability, we calibrated the model using Markov chain Monte Carlo (MCMC) technique. Although the simulations and the research are still ongoing, preliminary results from the MCMC calibration can be described as very promising considering that the model is still at relatively early stage. We will present the model and its dynamics as well as results from the MCMC calibration and the comparison with Siikaneva flux data.

  19. Remote estimation of net CO2 emission from boreal ecosystems

    Science.gov (United States)

    Rogers, C. A.; Strachan, I. B.

    2010-12-01

    Hydroelectricity is the main source of power in the province of Quebec, Canada. While hydroelectricity is considered to be a relatively green source of energy, reservoir creation is a land use change that involves flooding terrestrial ecosystems and thus a loss of greenhouse gas (GHG) uptake as well as direct GHG emission from decomposing vegetation. Both the lost sink for GHGs and direct emission from the reservoir surface must be included in estimating the net GHG emission attributable to the reservoir’s construction. These emissions can be determined using techniques such as eddy covariance, however, such methods are often costly and time consuming, and require frequent access to remote locations. Remote sensing is able to provide spatially continuous data over large areas, minimizing the need for ground based measurements. We tested the ability of the photochemical reflectance index (PRI) and normalized difference vegetation index (NDVI) to predict fluxes of carbon dioxide in areas representative of boreal forests and peatlands flooded by the Eastmain 1 hydroelectric reservoir in the James Bay region of Quebec, Canada. We collected spectral measurements from hand-held and helicopter-based platforms, as well as continuously monitored the indices PRI and NDVI from tower-mounted sensors at a forest and peatland site. We then compared the vegetation indices to net fluxes of carbon dioxide measured by eddy covariance at each site. PRI was related to fluxes at both the forest and peatland sites, suggesting it is possible to remotely estimate carbon dioxide uptake by vegetation in boreal forests and peatlands and thus greenhouse gas emissions resulting from land use changes in boreal regions, such as reservoir inundation.

  20. Disturbance legacies and climate jointly drive tree growth and mortality in an intensively studied boreal forest.

    Science.gov (United States)

    Bond-Lamberty, Ben; Rocha, Adrian V; Calvin, Katherine; Holmes, Bruce; Wang, Chuankuan; Goulden, Michael L

    2014-01-01

    Most North American forests are at some stage of post-disturbance regrowth, subject to a changing climate, and exhibit growth and mortality patterns that may not be closely coupled to annual environmental conditions. Distinguishing the possibly interacting effects of these processes is necessary to put short-term studies in a longer term context, and particularly important for the carbon-dense, fire-prone boreal forest. The goals of this study were to combine dendrochronological sampling, inventory records, and machine-learning algorithms to understand how tree growth and death have changed at one highly studied site (Northern Old Black Spruce, NOBS) in the central Canadian boreal forest. Over the 1999-2012 inventory period, mean tree diameter increased even as stand density and basal area declined significantly. Tree mortality averaged 1.4 ± 0.6% yr-(1), with most mortality occurring in medium-sized trees; new recruitment was minimal. There have been at least two, and probably three, significant influxes of new trees since stand initiation, but none in recent decades. A combined tree ring chronology constructed from sampling in 2001, 2004, and 2012 showed several periods of extreme growth depression, with increased mortality lagging depressed growth by ~5 years. Higher minimum and maximum air temperatures exerted a negative influence on tree growth, while precipitation and climate moisture index had a positive effect; both current- and previous-year data exerted significant effects. Models based on these variables explained 23-44% of the ring-width variability. We suggest that past climate extremes led to significant mortality still visible in the current forest structure, with decadal dynamics superimposed on slower patterns of fire and succession. These results have significant implications for our understanding of previous work at NOBS, the carbon sequestration capability of old-growth stands in a disturbance-prone landscape, and the sustainable management of

  1. Probing the debromination of the flame retardant decabromodiphenyl ether in sediments of a boreal lake.

    Science.gov (United States)

    Orihel, Diane M; Bisbicos, Tommy; Darling, Colin T R; Dupuis, Alain P; Williamson, Mary; Muir, Derek C G

    2016-03-01

    After decades of use of polybrominated diphenyl ethers (PBDEs) as flame retardants, a large reservoir of these toxins has accumulated in ecosystems worldwide. The present study used an innovative approach to examine whether the fully brominated PBDE decabromodiphenyl ether (decaBDE) degrades to more toxic congeners in aquatic environments. The authors incubated intact sediment microcosms with high-purity [(13)C]decaBDE in a remote boreal lake to assess its debromination under ambient conditions. Although the addition of [(13)C]decaBDE increased total PBDE concentrations in sediment more than 10-fold, the relative amount of [(13)C]decaBDE in sediment did not change significantly over a 1-mo incubation. However, observation of small quantities of lower-brominated [(13)C]BDEs lent support to the hypothesis that decaBDE is slowly debrominated. The authors observed a significant increase in octaBDEs and nonaBDEs in profundal, but not littoral, sediment over 30 d. A second experiment in which sediment was incubated under different light and oxygen regimes yielded a surprising result-oxygen significantly stimulated the formation of octaBDEs and nonaBDEs. The authors also conducted a large-scale in situ enclosure experiment in which they followed the fate of experimentally added decaBDE in sediment over 26 mo, but that study yielded little evidence of decaBDE debromination. Overall, the authors suggest that the debromination of decaBDE occurs very slowly, if at all, in natural sediment of boreal lakes, in contrast to the rapid degradation kinetics reported by most laboratory-based studies, which are usually conducted by dissolving decaBDE in organic solvents. The findings reinforce the need for field studies on contaminant fate to inform environmental policy decisions. PMID:26332257

  2. Disentangling legacy effects from environmental filters of postfire assembly of boreal tree assemblages.

    Science.gov (United States)

    Brown, Carissa D; Liu, Juxin; Yan, Guohua; Johnstone, Jill F

    2015-11-01

    Disturbance plays a key role in driving ecological responses by creating opportunities for new ecological communities to assemble and by directly influencing the outcomes of assembly. Legacy effects (such as seed banks) and environmental filters can both influence community assembly, but their effects are impossible to separate with observational data. Here, we used seeding experiments in sites covering a broad range of postdisturbance conditions to tease apart the effects of seed availability, environmental factors, and disturbance characteristics on early community assembly after fire. We added seed of four common boreal trees to experimental plots in 55 replicate sites in recently burned areas of black spruce forest in northwestern North America. Seed addition treatments increased the probability of occurrence for all species, indicating a widespread potential for seed limitation to affect patterns of recruitment after fire. Small-seeded. species (aspen and birch) were most sensitive to environmental factors such as soil moisture and organic layer depth, suggesting a role for niche-based environmental filtering in community assembly. Fire characteristics related to severity and frequency were also important drivers of seedling regeneration, indicating the potential for disturbance to mediate environmental filters and legacy effects on seed availability. Because effects of seed availability are typically impossible to disentangle from environmental constraints on recruitment in observational studies, legacy effects contingent on vegetation history may be misinterpreted as being driven by strong environmental filters. Results from the seeding experiments suggest that vegetation legacies affecting seed availability play a pivotal role in shaping patterns of community assembly after fire in these low-diversity boreal forests. PMID:27070021

  3. Bryophyte-cyanobacteria associations contribute to ecosystem-N-budget of boreal forest

    Science.gov (United States)

    Salemaa, Maija; Lindroos, Antti-Jussi; Merilä, Päivi; Mäkipää, Raisa; Smolander, Aino

    2014-05-01

    Bryophytes frequently dominate the ground vegetation on the forest floor in boreal region. Northern ecosystems are often nitrogen limited, and therefore biological nitrogen (N2) fixation of bryophyte-associated microbes is an important source of new N. In this study we estimated the N stock of bryophyte layer and the N input rate by N2 fixation of bryophyte-cyanobacteria associations at the ecosystem level. We studied 12 intensively monitored forest ecosystem plots (ICP Forests Level II) along a latitudinal gradient in Finland during 2009-2013. The total biomass and N stock of the bryophytes varied 700-2000 kg ha-1 and 9-23 kg ha-1, respectively. N2 fixation rate associated to bryophytes increased towards the north and was at highest 1-2 kg N ha-1 year-1 (based on the bryophyte biomass in the monitoring plots). This N input was at the same level as the N deposition in the northern Finland (1.5 kg N ha-1 year-1). In comparison, via needle litterfall and other tree litter c.a. 5 kg N ha-1 is annually returned to the nutrient cycle. In southern Finland, very low rates of N2 fixation were found probably because of inhibition by the anthropogenic N deposition. The upper parts of the bryophyte shoots showed 2-3 times higher N2-fixing rate than the lower parts, but differences between Hylocomium splendens and Pleurozium schreberi were minor. However, Dicranum species showed much lower N2 fixation rates compared to these two species. The moisture level of bryophytes and light/temperature conditions regulated strongly the rate of N2-fixing activity. The results showed that the bryophyte layer significantly contributes to the N input and plays an important role in controlling the N and C balances of boreal forests.

  4. No diurnal variation in rate or carbon isotope composition of soil respiration in a boreal forest

    International Nuclear Information System (INIS)

    This study evaluated the diurnal variability in the rate and stable carbon isotope ratio ((delta)13C) of soil respiration in a northern boreal forest, measured with opaque chambers after the removal of understory vegetation. The experiment was conducted in June and August 2004 at the Picea abies L. Karst-dominated Flakaliden Research Forest in northern Sweden, using unfertilized girdled-tree plots and unfertilized non-girdled tree plots. Soil respiration and (delta)13C of soil-respired carbon dioxide (CO2) were measured every 4 hours on 6 plots, with a total of 11 sampling times over each 48 hour period. The purpose was to clarify an earlier study regarding the origin of diurnal patterns of soil CO2 flux. This study explored whether the diurnal patterns were the result of photosynthetic CO2 uptake during the day by the understory or whether there were underlying trends in soil respiration driven by plant root allocation. The sampling campaigns undertaken in this study investigated whether diurnal variations in soil respiration rate and (delta)13C exist in this ecosystem when no understory vegetation is present. Shoot photosynthesis and environmental parameters were measured simultaneously. Despite significant variations in climatic conditions and shoot photosynthetic rates in non-girdled trees, no diurnal patterns in soil respiration rates and (delta)13C were noted in either treatment. The lack of detectable diurnal changes in both treatments indicates that modeling of daily boreal forest carbon balances based on single instantaneous measurements are unlikely to be misconstrued by substantial diurnal trends. However, it was suggested that spatial variable should be accounted for, given the large standard errors. The impact of tree girdling on soil respiration rates also emphasized the significance of canopy photosynthesis in driving soil processes. 37 refs., 2 figs

  5. Successional change in photosynthetic capacities after wildfires across the North American boreal forests

    Science.gov (United States)

    Tahara, N.; Ueyama, M.; Iwata, H.; Ichii, K.; Harazono, Y.; Nagano, H.

    2015-12-01

    Wildfire is a major disturbance across the North American boreal forests. Canopy ecophysiology is important to understand recovery of carbon dioxide and water vapor fluxes after wildfires. We developed a big-leaf model coupled photosynthesis (Farquhar et al., 1980) and stomatal conductance (Ball et al., 1987) models. We inputted eddy covariance data from fire chronosequence across the North American boreal forests into the big-leaf model for optimizing parameters: maximum carboxylation rate at 25℃ (Vcmax25) and stomatal conductance parameters. The model was optimized with a global optimization technique: SCE-UA method (Duan et al., 1994). The estimated canopy-scale parameters were then downscaled into a leaf scale (vcmax25; values per sun leaf area) using a two-leaf radiation transfer model (de Pury and Farquhar, 1997) and leaf area index. We used 6 sites from two fire chronosequence in Alaska (1~, 3~, 5~, 15~ and 80~ years after fire; Liu et al., 2005; Iwata et al., 2011) and 6 sites from a Canadian chronosequence study (6~, 15~, 23~, 40~ and 74~ years after fire; Goulden et al., 2010). Preliminary results showed clear seasonal variations in canopy-scale Vcmax25 with the maximum during the summer. In Alaska, the downscaled vcmax25 for four years after fire exceeded those of mature forests, indicating that the photosynthetic capacity recovered quickly in the early successional stage. This quick recovery was not seen in gross primary productivity. We will show the variations of the ecophysiological parameters in terms of environment conditions and stand age. References Ball et al., 1987: In Progress in Photosynthesis Research, 221-224. de Pury and Farquhar, 1997: Plant, Cell and Environ., 20, 537-557. Duan et al., 1994: J. Hydrology, 158, 265-284. Farquhar et al., 1980: Planta, 149, 78-90. Goulden et al., 2010: Global Change Biol., 17, 855-871. Iwata et al., 2011: SOLA., 7, 105-108. Liu et al., 2005: J. Geophys. Res., 110, D13101.

  6. Summer fluxes of nitrous oxide from boreal forest

    Czech Academy of Sciences Publication Activity Database

    Macháčová, Kateřina; Pihlatie, M.; Halmeenmäki, E.; Pavelka, Marian; Dušek, Jiří; Bäck, J.; Urban, Otmar

    Brno: Global Change Research Centre, The Czech Academy of Sciences, v. v. i., 2015 - (Urban, O.; Šprtová, M.; Klem, K.), s. 78-81 ISBN 978-80-87902-10-3. [Global Change: A Complex Challenge /4th/. Brno (CZ), 23.03.2015-24.03.2015] R&D Projects: GA MŠk(CZ) LO1415; GA MŠk EE2.3.20.0246 Institutional support: RVO:67179843 Keywords : boreal forest * greenhouse gases * forest ecosystem * Picea abies * Pinus Silvestris Subject RIV: EH - Ecology, Behaviour

  7. Hydrogen peroxide distribution, production, and decay in boreal lakes

    OpenAIRE

    Häkkinen, P J; Anesio, Alexandre Magno; Granéli, Wilhelm

    2004-01-01

    The distribution, production, and decay of hydrogen peroxide (H2O2) were studied in 10 boreal lakes of differing physical-chemical characteristics. Diurnal and vertical fluctuations in H2O2 concentration were followed in the lakes by sampling at six depths three times per day. In addition, incubations of water filtered through 0.2-mu mesh were made under artificial irradiation to study the abiotic production and decay of H2O2. H2O2 concentrations after 8 h of artificial irradiation were signi...

  8. Radionuclide transport and bioaccumulation processes in upland and boreal environments

    International Nuclear Information System (INIS)

    In order to access the impact of a proposed repository for radioactive waste in Cumbria, England, it is necessary to evaluate the processes affecting the transfer of radionuclides in natural and semi-natural environments and to derive relevant modelling parameters. To date, two environments, upland temperate and boreal, have been considered. It is intended to extend this work to include information and data for alpine and tundra environments. A critical review of the literature for the four appropriate ecosystems is being carried out and an electronic database of relevant parameter values is being created

  9. Gamma-ray irradiation of a boreal forest ecosystem

    International Nuclear Information System (INIS)

    A long-term radiation ecology research project called Field Irradiator - Gamma (FIG) began at the Whiteshell Nuclear Research Establishment in 1968. The experimental area is in southeastern Manitoba and is located on the western edge of the Precambrian shield. The project studies the ecological effects continuous exposure to a gradient of gamma radiation has on a mixed boreal forest ecosystem. The gradient ranges from 1 to 460,000 times the natural background radiation level. This paper describes the forest, the gamma irradiator and its radiation field, and the research program

  10. The affection of boreal forest changes on imbalance of Nature (Invited)

    Science.gov (United States)

    Tana, G.; Tateishi, R.

    2013-12-01

    Abstract: The balance of nature does not exist, and, perhaps, never has existed [1]. In other words, the Mother Nature is imbalanced at all. The Mother Nature is changing every moment and never returns to previous condition. Because of the imbalance of nature, global climate has been changing gradually. To reveal the imbalance of nature, there is a need to monitor the dynamic changes of the Earth surface. Forest cover and forest cover change have been grown in importance as basic variables for modelling of global biogeochemical cycles as well as climate [2]. The boreal area contains 1/3 of the earth's trees. These trees play a large part in limiting harmful greenhouse gases by aborbing much of the earth's carbon dioxide (CO2) [3]. The boreal area mainly consists of needleleaf evergreen forest and needleleaf deciduous forest. Both of the needleleaf evergreen forest and needleleaf deciduous forest play the important roles on the uptake of CO2. However, because of the dormant period of needleleaf evergreen forest are shorter than that of needleleaf deciduous forest, needleleaf evergreen forest makes a greater contribution to the absorbtion of CO2. Satellite sensor because of its ability to observe the Earth continuously, can provide the opportunity to monitor the dynamic changes of the Earth. In this study, we used the MODerate resolution Imaging Spectroradiometer (MODIS) satellite data to monitor the dynamic change of boreal forest area which are mainly consist from needleleaf evergreen forest and needleleaf deciduous forest during 2003-2012. Three years MODIS data from the year 2003, 2008 and 2012 were used to detect the forest changed area. A hybrid change detection method which combines the threshold method and unsupervised classification method was used to detect the changes of forest area. In the first step, the difference of Normalized Difference Vegetation Index (NDVI) of the three years were calculated and were used to extract the changed areas by the

  11. CO2 and CH4 fluxes and carbon balance in the atmospheric interaction of boreal peatlands

    International Nuclear Information System (INIS)

    Release of CO2 from peat was studied using IR analyzer in a range of boreal peatlands under varying nutrient status and moisture conditions. Root associated CO2 efflux was separated from the total release by experiments both in the field and in a greenhouse. Emissions of CO2 and CH4 (the latter by gas chromatography) were measured during the snow-covered period and their contribution to the annual fluxes of these gases was inspected. Ecosystem exchange of CO2 under varying irradiation, temperature and moisture conditions was measured at different microsites at two peatland sites with different nutrient ecology. One site represented minerotrophic conditions during a wet growing season and the other site ombrotrophic conditions during an exceptionally dry growing season. Annual carbon balances were compiled for the two sites, and the role of the microsites in the annual carbon balance and CH4 release was studied. The Holocene history of CO2 sequestration and CH4 emission dynamics in a raised mire were simulated using lateral and vertical growth rates derived from radiocarbon ages of peat samples from mire bottom and vertical cores. The model was formulated for a geographic information system (GIS). Artificial or natural lowering of water table increased CO2 release from peat. A drought lasting from late May to July caused a 90 g C m2 net loss in the annual C balance of a natural ombrotrophic bog. In drained forested sites the increase in peat CO2 release could be even 100 %, but the development of the tree layer at least partially compensated for these losses. Wet conditions induced a net accumulation of 67 g C m-2a-1 in the minerotrophic fen site, while the long term average accumulation rate is estimated to be only 15 g C m-2a-1 for Finnish fens. Carbon balance in boreal peatlands is thus extremely sensitive to year-to-year climatic variations. Root activity of vascular plants contributed to the total peat CO2 efflux by 10-40 % as root respiration and root

  12. Modelling soil temperature and moisture and corresponding seasonality of photosynthesis and transpiration in a boreal spruce ecosystem

    Directory of Open Access Journals (Sweden)

    S. H. Wu

    2012-05-01

    Full Text Available Recovery of photosynthesis and transpiration is strongly restricted by low temperatures in air and/or soil during the transition period from winter to spring in boreal zones. The extent to which air temperature (Ta and soil temperature (Ts influence the seasonality of photosynthesis and transpiration of a boreal spruce ecosystem was investigated using a process-based ecosystem model (CoupModel together with eddy covariance (EC data from one eddy flux tower and nearby soil measurements at Knottåsen, Sweden. A Monte Carlo based uncertainty method (GLUE provided prior and posterior distributions of simulations representing a wide range of soil conditions and performance indicators. The simulated results showed sufficient flexibility to predict the measured cold and warm Ts in the moist and dry plots around the eddy flux tower. Moreover, the model presented a general ability to describe both biotic and abiotic processes for the Norway spruce stand. The dynamics of sensible heat fluxes were well described the corresponding latent heat fluxes and net ecosystem exchange of CO2. The parameter ranges obtained are probably valid to represent regional characteristics of boreal conifer forests, but were not easy to constrain to a smaller range than that produced by the assumed prior distributions. Finally, neglecting the soil temperature response function resulted in fewer behavioural models and probably more compensatory errors in other response functions for regulating the seasonality of ecosystem fluxes.

  13. Impacts of chronic anthropogenic noise from energy-sector activity on abundance of songbirds in the boreal forest.

    Science.gov (United States)

    Bayne, Erin M; Habib, Lucas; Boutin, Stan

    2008-10-01

    The effects of human activities in forests are often examined in the context of habitat conversion. Changes in habitat structure and composition are also associated with increases in the activity of people with vehicles and equipment, which results in increases in anthropogenic noise. Anthropogenic noise may reduce habitat quality for many species, particularly those that rely on acoustic signals for communication. We compared the density and occupancy rate of forest passerines close to versus far from noise-generating compressor stations and noiseless well pads in the boreal forest of Alberta, Canada. Using distance-based sampling, we found that areas near noiseless energy facilities had a total passerine density 1.5 times higher than areas near noise-producing energy sites. The White-throated Sparrow (Zonotrichia albicollis), Yellow-rumped Warbler (Dendroica coronata), and Red-eyed Vireo (Vireo olivaceus) were less dense in noisy areas. We used repeat sampling to estimate occupancy rate for 23 additional species. Seven had lower conditional or unconditional occupancy rates near noise-generating facilities. One-third of the species examined showed patterns that supported the hypothesis that abundance is influenced by anthropogenic noise. An additional 4 species responded negatively to edge effects. To mitigate existing noise impacts on birds would require approximately $175 million. The merits of such an effort relative to other reclamation actions are discussed. Nevertheless, given the $100 billion energy-sector investment planned for the boreal forest in the next 10 years, including noise suppression technology at the outset of construction, makes noise mitigation a cost-effective best-management practice that might help conserve high-quality habitat for boreal birds. PMID:18616740

  14. Size-mediated tree transpiration along soil drainage gradients in a boreal black spruce forest wildfire chronosequence.

    Science.gov (United States)

    Angstmann, J L; Ewers, B E; Kwon, H

    2012-05-01

    Boreal forests are crucial to climate change predictions because of their large land area and ability to sequester and store carbon, which is controlled by water availability. Heterogeneity of these forests is predicted to increase with climate change through more frequent wildfires, warmer, longer growing seasons and potential drainage of forested wetlands. This study aims at quantifying controls over tree transpiration with drainage condition, stand age and species in a central Canadian black spruce boreal forest. Heat dissipation sensors were installed in 2007 and data were collected through 2008 on 118 trees (69 Picea mariana (Mill.) Britton, Sterns & Poggenb. (black spruce), 25 Populus tremuloides Michx. (trembling aspen), 19 Pinus banksiana Lamb. (jack pine), 3 Larix laricina (Du Roi) K. Koch (tamarack) and 2 Salix spp. (willow)) at four stand ages (18, 43, 77 and 157 years old) each containing a well- and poorly-drained stand. Transpiration estimates from sap flux were expressed per unit xylem area, J(S), per unit ground area, E(C) and per unit leaf area, E(L), using sapwood (A(S)) and leaf (A(L)) area calculated from stand- and species-specific allometry. Soil drainage differences in transpiration were variable; only the 43- and 157-year-old poorly-drained stands had ∼ 50% higher total stand E(C) than well-drained locations. Total stand E(C) tended to decrease with stand age after an initial increase between the 18- and 43-year-old stands. Soil drainage differences in transpiration were controlled primarily by short-term physiological drivers such as vapor pressure deficit and soil moisture whereas stand age differences were controlled by successional species shifts and changes in tree size (i.e., A(S)). Future predictions of boreal climate change must include stand age, species and soil drainage heterogeneity to avoid biased estimates of forest water loss and latent energy exchanges. PMID:22539635

  15. Changing Arctic ecosystems--the role of ecosystem changes across the Boreal-Arctic transition zone on the distribution and abundance of wildlife populations

    Science.gov (United States)

    McNew, Lance; Handel, Colleen; Pearce, John; DeGange, Anthony R.; Holland-Bartels, Leslie; Whalen, Mary

    2013-01-01

    Arctic and boreal ecosystems provide important breeding habitat for more than half of North America’s migratory birds as well as many resident species. Northern landscapes are projected to experience more pronounced climate-related changes in habitat than most other regions. These changes include increases in shrub growth, conversion of tundra to forest, alteration of wetlands, shifts in species’ composition, and changes in the frequency and scale of fires and insect outbreaks. Changing habitat conditions, in turn, may have significant effects on the distribution and abundance of wildlife in these critical northern ecosystems. The U.S. Geological Survey (USGS) is conducting studies in the Boreal–Arctic transition zone of Alaska, an environment of accelerated change in this sensitive margin between Arctic tundra and boreal forest.

  16. Nitrogen balance of a boreal Scots pine forest

    Directory of Open Access Journals (Sweden)

    J. F. J. Korhonen

    2012-08-01

    Full Text Available The productivity of boreal forests is considered to be limited by low nitrogen (N availability. Increased atmospheric N deposition has altered the functioning and N cycling of these N-sensitive ecosystems. The most important components of N pools and fluxes were measured in a boreal Scots pine stand in Hyytiälä, Southern Finland. The measurement at the site allowed direct estimations of nutrient pools in the soil and biomass, inputs from the atmosphere and outputs as drainage flow and gaseous losses from two micro-catchments. N was accumulating to the system with a rate of 7 kg N ha−1 yr−1. Nitrogen input as atmospheric deposition was 7.4 kg N ha−1 yr−1. Dry deposition and organic N in wet deposition contributed over half of the input in deposition. Total outputs were 0.4 kg N ha−1 yr−1, the most important outputs being N2O emission to the atmosphere and organic N flux in drainage flow. Nitrogen uptake and retranslocation were as important sources of N for plant growth. Most of the uptaken N originated from decomposition of organic matter, and the fraction of N that could originate directly from deposition was about 30%. In conclusion, atmospheric N deposition fertilizes the site considerably.

  17. Controls on CH4 flux from an Alaskan boreal wetland

    Science.gov (United States)

    Moosavi, Sadredin C.; Crill, Patrick M.; Pullman, Erik R.; Funk, Dale W.; Peterson, Kim M.

    1996-06-01

    Factors controlling the flux of the radiatively important trace gas methane (CH4) from boreal wetlands were examined at three sites along a moisture gradient from a treed low-shrub bog to an open floating graminoid bog in Fairbanks, Alaska. In the summer of 1992 average static chamber flux measurements were -0.02, 71.5, and 289 mg CH4/m2/d in dry, wet, and floating mat communities, respectively. In contrast, the warmer, drier 1993 field season flux measurements were -0.02, 42.9 and 407 mg CH4/m2/d. The data indicate that despite net oxidation of CH4 in the dry regions of the bog, the wetland is a net source of CH4, with fluxes ranging across three orders of magnitude between different plant communities. Comparison with water levels suggests that CH4 flux is turned on and off by changes in site hydrology. In sites where sufficient moisture is present for methanogenesis to occur, CH4 flux appears to be temperature limited, responding exponentially to soil temperature changes. The combined effects of hydrology and temperature create hot spots of CH4 flux within boreal wetlands. The plant communities within Lemeta Bog respond differently to changes in temperature and moisture availability, creating both positive and negative feedbacks to potential global climate change.

  18. What governs the presence of residual vegetation in boreal wildfires?

    Science.gov (United States)

    Araya, Yikalo H.; Remmel, Tarmo K.; Perera, Ajith H.

    2016-04-01

    Wildfires are frequent boreal forest disturbances in Canada, and emulating their patterns with forest harvesting has emerged as a common forest management goal. Wildfires contain many patches of residual vegetation of various size, shape, and composition; understanding their characteristics provides insights for improved emulation criteria. We studied the occurrence of residual vegetation within eleven boreal wildfire events in a natural setting; fires ignited by lightning, no suppression efforts, and no prior anthropogenic disturbances. Relative importance of the measurable geo-environmental factors and their marginal effects on residual presence are studied using Random Forests. These factors included distance from natural firebreaks (wetland, bedrock and non-vegetated areas, and water), land cover, and topographic variables (elevation, slope, and ruggedness index). We present results at spatial resolutions ranging from four to 64 m while emphasizing four and 32 m since they mimic IKONOS- and Landsat-type images. Natural firebreak features, especially the proximity to wetlands, are among the most important variables that explain the likelihood residual occurrence. The majority of residual vegetation areas are concentrated within 100 m of wetlands. Topographic variables, typically important in rugged terrain, are less important in explaining the presence of residuals within our study fires.

  19. Stocks, Chemistry, and Sensitivity to Climate Change of Dead Organic Matter Along the Canadian Boreal Forest Transect Case Study

    Energy Technology Data Exchange (ETDEWEB)

    Preston, C.M.; Norris, C. [Pacific Forestry Centre, Natural Resources Canada, Victoria, BC, V8Z 1M5 (Canada); Bhatti, J.S. [Northern Forestry Centre, Natural Resources Canada, Edmonton, AB, T6H 3S5 (Canada); Flanagan, L.B. [Department of Biological Sciences, University of Lethbridge, Lethbridge, AB, T1K 3M4 (Canada)

    2006-01-15

    Improving our ability to predict the impact of climate change on the carbon (C) balance of boreal forests requires increased understanding of site-specific factors controlling detrital and soil C accumulation. Jack pine (Pinus banksiana) and black spruce (Picea mariana) stands along the Boreal Forest Transect Case Study (BFTCS) in northern Canada have similar C stocks in aboveground vegetation and large woody detritus, but thick forest floors of poorly-drained black spruce stands have much higher C stocks, comparable to living biomass. Their properties indicate hindered decomposition and N cycling, with high C/N ratios, strongly stratified and depleted d13C and d15N values, high concentrations of tannins and phenolics, and 13C nuclear magnetic resonance (NMR) spectra typical of poorly decomposed plant material, especially roots and mosses. The thinner jack pine forest floor appears to be dominated by lichen, with char in some samples. Differences in quantity and quality of aboveground foliar and woody litter inputs are small and unlikely to account for the contrasts in forest floor accumulation and properties. These are more likely associated with site conditions, especially soil texture and drainage, exacerbated by increases in sphagnum coverage, forest floor depth, and tannins. Small changes in environmental conditions, especially reduced moisture, could trigger large C losses through rapid decomposition of forest floor in poorly drained black spruce stands in this region.

  20. The Effect of Bark Borer Herbivory on BVOC Emissions in Boreal Forests and Implications for SOA Formation

    Science.gov (United States)

    Faiola, Celia; Joutsensaari, Jorma; Holopainen, Jarmo; Yli-Juuti, Taina; Kokkola, Harri; Blande, James; Guenther, Alex; Virtanen, Annele

    2015-04-01

    Herbivore outbreaks are expected to increase as a result of climate change. These outbreaks can have significant effects on the emissions of biogenic volatile organic compound (BVOC) from vegetation, which contribute to the formation of secondary organic aerosol (SOA). We have synthesized the published results investigating changes to BVOC emissions from herbivory by the pine weevil, Hylobius abietis--a bark borer herbivore. Previous lab experiments have shown that bark borer herbivory on Scots pine trees increases monoterpene emissions 4-fold and sesquiterpene emissions 7-fold. Norway spruce exhibits a similar response. The BVOCs most impacted were linalool, beta-phellandrene, limonene, alpha-pinene, beta-pinene, myrcene, and sesquiterpenes like beta-farnesene, beta-bourbonene, and longifolene. The quantitative results from these studies were used to estimate potential impacts of bark borer herbivory on BVOC emissions at a regional scale using the Model of Emissions of Gases and Aerosols from Nature (MEGAN). MEGAN was run under baseline and herbivore outbreak conditions for a typical boreal forest environment in spring. Emissions output from MEGAN was used to run a microphysical box model to estimate the SOA formation potential under baseline and outbreak conditions. This estimate could provide us with an upper limit to the potential impact of bark borer outbreaks on SOA formation in a boreal forest.

  1. National recovery strategy for woodland caribou (Rangifer tarandus caribou, boreal population, in Canada

    Directory of Open Access Journals (Sweden)

    Dave Hervieux

    2007-04-01

    Full Text Available Recovery planning for the boreal population of woodland caribou is a complex task, spanning eight Canadian provinces and territories. To accommodate unique situations across the country, recovery planning for this Species at Risk Act-listed threatened species is occurring at both provincial/ territorial and national levels. The national recovery strategy strives to identify nationally important issues and provide direction for provinces and territories as they plan and implement boreal caribou recovery within their jurisdictions. The national vision is to conserve and recover boreal caribou and their habitat across Canada. Specific goals are to: 1 Prevent extirpation of local boreal caribou populations from all existing caribou ranges; and 2 Maintain or enhance local boreal caribou populations at or to self-sustaining levels within all existing caribou ranges; and 3 Maintain or enhance boreal caribou habitat to support self-sustaining local populations. Nineteen broad national approaches are identified. These approaches include items relating to: habitat planning and management, caribou population monitoring and management, management of human-caused mortality, management of other wildlife species, consideration of government legislation and policy,promotion of stewardship and public outreach, and research. Specific outcomes are provided for each stated recovery approach. For more information on Canada's national recovery strategy for the boreal population of woodland caribou please see www.speciesatrisk.gc.ca/recovery/default_e.cfm

  2. Morphological Studies of Synechocystis sp. UNIWG under Polyhydroxyalkanoate Accumulating Conditions

    Directory of Open Access Journals (Sweden)

    Yew, S. P.

    2005-01-01

    Full Text Available Some cyanobacteria are capable of producing polyhydroxyalkanoate (PHA, among which is the unicellular Synechocystis sp. Here, we report the identification and preliminary characterization of a newly isolated strain of Synechocystis sp. UNIWG that is capable of accumulating unusually high number of PHA granules. This cyanobacterium was isolated from oil-contaminated brackish water sample from Wadi Gaza, Palestine. Surprisingly, Nile Blue A staining of PHA-accumulating cells failed to reveal the accumulated PHA granules. Ultrastructural analysis of Synechocystis sp. UNIWG cells grown under nitrogen limiting conditions revealed the presence of up to 17 electron-transparent granules in the cell cytoplasm. Gas chromatography analysis further revealed that these cells contain up to 14 wt% poly(3-hydroxybutyrate of the cell dry weight. Ultrastructural analysis also revealed that Synechocystis sp. UNIWG cells from the growth phase were covered with a dense layer of pilus like structures. However, these pilus-like structures were not observed in cells from the PHA-accumulation phase. The possible roles of these pilus-like structures and PHA accumulation for the survival of this cyanobacterium is discussed here.

  3. Seventeen-year trends in spring and autumn phenophases of Betula pubescens in a boreal environment

    Science.gov (United States)

    Poikolainen, Jarmo; Tolvanen, Anne; Karhu, Jouni; Kubin, Eero

    2016-08-01

    Trends in the timing of spring and autumn phenophases of Betula pubescens were investigated in the southern, middle, and northern boreal zones in Finland. The field observations were carried out at 21 sites in the Finnish National Phenological Network in 1997-2013. The effective temperature sum of the thermal growth period, i.e. the sum of the positive differences between diurnal mean temperatures and 5 °C (ETS1), increased annually on average by 6-7 degree day units. Timing of bud burst remained constant in the southern and middle boreal zones but advanced annually by 0.5 day in the northern boreal zone. The effective temperature sum at bud burst (ETS2) showed no trend in the southern and middle boreal zones, whereas ETS2 increased on average from 20-30 to 50 degree day units in the northern boreal zone, almost to the same level as in the other zones. Increase in ETS2 indicates that the trees did not start their growth in very early spring despite warmer spring temperatures. The timing of leaf colouring and leaf fall remained almost constant in the southern boreal zones, whereas these advanced annually by 0.3 and 0.6 day in the middle boreal zone and by 0.6 and 0.4 day in the northern boreal zone, respectively. The duration of the growth period remained constant in all boreal zones. The results indicate high buffering capacity of B. pubescens against temperature changes. The study also shows the importance of the duration of phenological studies: some trends in spring phenophases had levelled out, while new trends in autumn phases had emerged after earlier studies in the same network for a shorter observation period.

  4. Seventeen-year trends in spring and autumn phenophases of Betula pubescens in a boreal environment

    Science.gov (United States)

    Poikolainen, Jarmo; Tolvanen, Anne; Karhu, Jouni; Kubin, Eero

    2015-12-01

    Trends in the timing of spring and autumn phenophases of Betula pubescens were investigated in the southern, middle, and northern boreal zones in Finland. The field observations were carried out at 21 sites in the Finnish National Phenological Network in 1997-2013. The effective temperature sum of the thermal growth period, i.e. the sum of the positive differences between diurnal mean temperatures and 5 °C (ETS1), increased annually on average by 6-7 degree day units. Timing of bud burst remained constant in the southern and middle boreal zones but advanced annually by 0.5 day in the northern boreal zone. The effective temperature sum at bud burst (ETS2) showed no trend in the southern and middle boreal zones, whereas ETS2 increased on average from 20-30 to 50 degree day units in the northern boreal zone, almost to the same level as in the other zones. Increase in ETS2 indicates that the trees did not start their growth in very early spring despite warmer spring temperatures. The timing of leaf colouring and leaf fall remained almost constant in the southern boreal zones, whereas these advanced annually by 0.3 and 0.6 day in the middle boreal zone and by 0.6 and 0.4 day in the northern boreal zone, respectively. The duration of the growth period remained constant in all boreal zones. The results indicate high buffering capacity of B. pubescens against temperature changes. The study also shows the importance of the duration of phenological studies: some trends in spring phenophases had levelled out, while new trends in autumn phases had emerged after earlier studies in the same network for a shorter observation period.

  5. Potential for Monitoring Snow Cover in Boreal Forests by Combining MODIS Snow Cover and AMSR-E SWE Maps

    Science.gov (United States)

    Riggs, George A.; Hall, Dorothy K.; Foster, James L.

    2009-01-01

    Monitoring of snow cover extent and snow water equivalent (SWE) in boreal forests is important for determining the amount of potential runoff and beginning date of snowmelt. The great expanse of the boreal forest necessitates the use of satellite measurements to monitor snow cover. Snow cover in the boreal forest can be mapped with either the Moderate Resolution Imaging Spectroradiometer (MODIS) or the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) microwave instrument. The extent of snow cover is estimated from the MODIS data and SWE is estimated from the AMSR-E. Environmental limitations affect both sensors in different ways to limit their ability to detect snow in some situations. Forest density, snow wetness, and snow depth are factors that limit the effectiveness of both sensors for snow detection. Cloud cover is a significant hindrance to monitoring snow cover extent Using MODIS but is not a hindrance to the use of the AMSR-E. These limitations could be mitigated by combining MODIS and AMSR-E data to allow for improved interpretation of snow cover extent and SWE on a daily basis and provide temporal continuity of snow mapping across the boreal forest regions in Canada. The purpose of this study is to investigate if temporal monitoring of snow cover using a combination of MODIS and AMSR-E data could yield a better interpretation of changing snow cover conditions. The MODIS snow mapping algorithm is based on snow detection using the Normalized Difference Snow Index (NDSI) and the Normalized Difference Vegetation Index (NDVI) to enhance snow detection in dense vegetation. (Other spectral threshold tests are also used to map snow using MODIS.) Snow cover under a forest canopy may have an effect on the NDVI thus we use the NDVI in snow detection. A MODIS snow fraction product is also generated but not used in this study. In this study the NDSI and NDVI components of the snow mapping algorithm were calculated and analyzed to determine how they changed

  6. Do protozoa control the elimination of Vibrio cholerae in brackish water?

    Czech Academy of Sciences Publication Activity Database

    Martínez-P., M. E.; Macek, Miroslav; Castro-G., M. T.

    2004-01-01

    Roč. 89, č. 2 (2004), s. 215-227. ISSN 1434-2944 R&D Projects: GA MŠk(CZ) ME 296 Grant ostatní: UNAM/DGAPA/PAPIT(MX) IN216796 Keywords : ciliate feeding * selectivity * toxin producing bacteria Subject RIV: EE - Microbiology, Virology Impact factor: 0.742, year: 2004

  7. Isolation and evaluation of oil-producing microalgae from subtropical coastal and brackish waters.

    Directory of Open Access Journals (Sweden)

    David K Y Lim

    Full Text Available Microalgae have been widely reported as a promising source of biofuels, mainly based on their high areal productivity of biomass and lipids as triacylglycerides and the possibility for cultivation on non-arable land. The isolation and selection of suitable strains that are robust and display high growth and lipid accumulation rates is an important prerequisite for their successful cultivation as a bioenergy source, a process that can be compared to the initial selection and domestication of agricultural crops. We developed standard protocols for the isolation and cultivation for a range of marine and brackish microalgae. By comparing growth rates and lipid productivity, we assessed the potential of subtropical coastal and brackish microalgae for the production of biodiesel and other oil-based bioproducts. This study identified Nannochloropsis sp., Dunaniella salina and new isolates of Chlorella sp. and Tetraselmis sp. as suitable candidates for a multiple-product algae crop. We conclude that subtropical coastal microalgae display a variety of fatty acid profiles that offer a wide scope for several oil-based bioproducts, including biodiesel and omega-3 fatty acids. A biorefinery approach for microalgae would make economical production more feasible but challenges remain for efficient harvesting and extraction processes for some species.

  8. The distribution and ecology of the fresh- and brackish-water Medusae of the world

    OpenAIRE

    Dumont, H.J.

    1994-01-01

    Limnocnida and Craspedacusta are the two main genera of Cnidaria from continental waters which have a free-swimming medusa in their life cycle. Both originated in tropical-subtropical Asia, but Limnocnida is also found in Africa, with one species (L. tanganjicae) perhaps endemic to lake Tanganyika. Halmomises from Trinidad, and two genera (Mansariella, Keralica) from India have limited ranges. No freshwater medusae evolved in Europe and the Americas (aside from Trinidad), but Craspedacusta so...

  9. Integration of Ultrafiltration and Reverse Osmosis on purification of brackish waters: optimization trials

    OpenAIRE

    Travesset Mezquita, Marc

    2012-01-01

    Ultrafiltration (UF), due to its reliability, robustness and stable quality of the water produced , offers technical advantages over conventional pretreatments such as sand filtration coupled with coagulation/flocculation or activated carbon. In this study, the real case of a prototype designed, commissioned and operated consisting of an advanced Ultrafiltration unit (DOW™ UF) followed by a Reverse Osmosis system (Filmtec ™ Reverse Osmosis elements) is evaluated. The work prese...

  10. Hatching success in brackish water of Perca fluviatilis eggs obtained from the western Baltic Sea

    DEFF Research Database (Denmark)

    Christensen, Emil Aputsiaq Flindt; Skovrind, Mikkel; Olsen, Morten Tange;

    2016-01-01

    population genetically among other European perch populations, individual egg samples were sequenced for a 390 base pair fragment of the mtDNA Dloop region. Hatching occurred at all four salinities, with no statistical differences among treatments. Successful hatching at 12 ‰ is well above salinities of 7......‰, which has previously been the highest reported from in vivo studies. This discrepancy is likely to be a result of methodological differences (e.g. different temperature) or perhaps interspecific variability in egg hatching abilities among perch populations. The perch from the present study consisted of...

  11. Echinicola shivajiensis sp. nov., a novel bacterium of the family "Cyclobacteriaceae" isolated from brackish water pond

    Digital Repository Service at National Institute of Oceanography (India)

    Srinivas, T.N.R.; Tryambak, B.K.; AnilKumar, P.

    . Colonies were circular, 1-3 mm in diameter, smooth, shiny, orange, translucent and raised with entire margin on marine agar. The strain was positive for oxidase, catalase, phosphatase and arginine dihydrolase activities and negative for lysine... with entire margins. Grows at 5 to 40 o C with an optimum temperature of 30-37 o C and tolerates up to 12.0% (w/v) NaCl. Grows at pH 6 to 12 with an optimum pH of 7-8.5. Oxidase, catalase, arginine dihydrolase, Ala-Phe-Pro-arylamidase, β-galactosidase, β...

  12. CONCENTRATED SOLAR DISTILLATION AS A MEANS TO PURIFY SALINE/BRACKISH WATER

    Science.gov (United States)

    Initial experiments focused on the ability of the lens to deliver enough energy to produce water with minimal salt content. Raw sample waters were prepared using quantities of Epsom salt (MgSO47H2O) dissolved in purchased distilled water. Three separate ...

  13. Selective removal of arsenic and monovalent ions from brackish water reverse osmosis concentrate.

    Science.gov (United States)

    Xu, Pei; Capito, Marissa; Cath, Tzahi Y

    2013-09-15

    Concentrate disposal and management is a considerable challenge for the implementation of desalination technologies, especially for inland applications where concentrate disposal options are limited. This study has focused on selective removal of arsenic and monovalent ions from brackish groundwater reverse osmosis (RO) concentrate for beneficial use and safe environmental disposal using in situ and pre-formed hydrous ferric oxides/hydroxides adsorption, and electrodialysis (ED) with monovalent permselective membranes. Coagulation with ferric salts is highly efficient at removing arsenic from RO concentrate to meet a drinking water standard of 10 μg/L. The chemical demand for ferric chloride however is much lower than ferric sulfate as coagulant. An alternative method using ferric sludge from surface water treatment plant is demonstrated as an efficient adsorbent to remove arsenic from RO concentrate, providing a promising low cost, "waste treat waste" approach. The monovalent permselective anion exchange membranes exhibit high selectivity in removing monovalent anions over di- and multi-valent anions. The transport of sulfate and phosphate through the anion exchange membranes was negligible over a broad range of electrical current density. However, the transport of divalent cations such as calcium and magnesium increases through monovalent permselective cation exchange membranes with increasing current density. Higher overall salt concentration reduction is achieved around limiting current density while higher normalized salt removal rate in terms of mass of salt per membrane area and applied energy is attained at lower current density because the energy unitization efficiency decreases at higher current density. PMID:23892312

  14. Nitrification in brackish water recirculating aquaculture system integrated with activated packed bed bioreactor.

    Science.gov (United States)

    Rejish Kumar, V J; Joseph, Valsamma; Philip, Rosamma; Bright Singh, I S

    2010-01-01

    Recirculation aquaculture systems (RAS) depend on nitrifying biofilters for the maintenance of water quality, increased biosecurity and environmental sustainability. To satisfy these requirements a packed bed bioreactor (PBBR) activated with indigenous nitrifying bacterial consortia has been developed and commercialized for operation under different salinities for instant nitrification in shrimp and prawn hatchery systems. In the present study the nitrification efficiency of the bioreactor was tested in a laboratory level recirculating aquaculture system for the rearing of Penaeus monodon for a period of two months under higher feeding rates and no water exchange. Rapid setting up of nitrification was observed during the operation, as the volumetric total ammonia nitrogen removal rates (VTR) increased with total ammonia nitrogen (TAN) production in the system. The average Volumetric TAN Removal Rates (VTR) at the feeding rate of 160 g/day from 54-60th days of culture was 0.1533+/-0.0045 kg TAN/m(3)/day. The regression between VTR and TAN explained 86% variability in VTR (P<0.001). The laboratory level RAS demonstrated here showed high performance both in terms of shrimp biomass yield and nitrification and environmental quality maintenance. Fluorescent in-situ Hybridization analysis of the reactor biofilm ensured the presence of autotrophic nitrifier groups such as Nitrosococcus mobilis lineage, Nitrobacter spp and phylum Nitrospira, the constituent members present in the original consortia used for activating the reactors. This showed the stability of the consortia on long term operation. PMID:20150717

  15. Effects of predicted climatic changes on distribution of organic contaminants in brackish water mesocosms

    International Nuclear Information System (INIS)

    Predicted consequences of future climate change in the northern Baltic Sea include increases in sea surface temperatures and terrestrial dissolved organic carbon (DOC) runoff. These changes are expected to alter environmental distribution of anthropogenic organic contaminants (OCs). To assess likely shifts in their distributions, outdoor mesocosms were employed to mimic pelagic ecosystems at two temperatures and two DOC concentrations, current: 15 °C and 4 mg DOC L−1 and, within ranges of predicted increases, 18 °C and 6 mg DOC L−1, respectively. Selected organic contaminants were added to the mesocosms to monitor changes in their distribution induced by the treatments. OC partitioning to particulate matter and sedimentation were enhanced at the higher DOC concentration, at both temperatures, while higher losses and lower partitioning of OCs to DOC were observed at the higher temperature. No combined effects of higher temperature and DOC on partitioning were observed, possibly because of the balancing nature of these processes. Therefore, changes in OCs' fates may largely depend on whether they are most sensitive to temperature or DOC concentration rises. Bromoanilines, phenanthrene, biphenyl and naphthalene were sensitive to the rise in DOC concentration, whereas organophosphates, chlorobenzenes (PCBz) and polychlorinated biphenyls (PCBs) were more sensitive to temperature. Mitotane and diflufenican were sensitive to both temperature and DOC concentration rises individually, but not in combination. - Highlights: • More contaminants remained in the ecosystem at higher organic carbon levels. • More contaminants were lost in the higher temperature treatments. • The combined effects are competitive with respect to contaminant cycling. • The individual properties of each contaminant determine their respective fate

  16. Effects of predicted climatic changes on distribution of organic contaminants in brackish water mesocosms

    Energy Technology Data Exchange (ETDEWEB)

    Ripszam, M., E-mail: matyas.ripszam@chem.umu.se [Department of Chemistry, Umea University, 901 87 Umeå (Sweden); Gallampois, C.M.J. [Department of Chemistry, Umea University, 901 87 Umeå (Sweden); Berglund, Å. [Department of Ecology and Environmental Sciences, Umeå University, 901 87 Umeå (Sweden); Larsson, H. [Umeå Marine Sciences Centre, Umeå University, Norrbyn, 905 71 Hörnefors (Sweden); Andersson, A. [Department of Ecology and Environmental Sciences, Umeå University, 901 87 Umeå (Sweden); Tysklind, M.; Haglund, P. [Department of Chemistry, Umea University, 901 87 Umeå (Sweden)

    2015-06-01

    Predicted consequences of future climate change in the northern Baltic Sea include increases in sea surface temperatures and terrestrial dissolved organic carbon (DOC) runoff. These changes are expected to alter environmental distribution of anthropogenic organic contaminants (OCs). To assess likely shifts in their distributions, outdoor mesocosms were employed to mimic pelagic ecosystems at two temperatures and two DOC concentrations, current: 15 °C and 4 mg DOC L{sup −1} and, within ranges of predicted increases, 18 °C and 6 mg DOC L{sup −1}, respectively. Selected organic contaminants were added to the mesocosms to monitor changes in their distribution induced by the treatments. OC partitioning to particulate matter and sedimentation were enhanced at the higher DOC concentration, at both temperatures, while higher losses and lower partitioning of OCs to DOC were observed at the higher temperature. No combined effects of higher temperature and DOC on partitioning were observed, possibly because of the balancing nature of these processes. Therefore, changes in OCs' fates may largely depend on whether they are most sensitive to temperature or DOC concentration rises. Bromoanilines, phenanthrene, biphenyl and naphthalene were sensitive to the rise in DOC concentration, whereas organophosphates, chlorobenzenes (PCBz) and polychlorinated biphenyls (PCBs) were more sensitive to temperature. Mitotane and diflufenican were sensitive to both temperature and DOC concentration rises individually, but not in combination. - Highlights: • More contaminants remained in the ecosystem at higher organic carbon levels. • More contaminants were lost in the higher temperature treatments. • The combined effects are competitive with respect to contaminant cycling. • The individual properties of each contaminant determine their respective fate.

  17. Assessing various drought indicators in representing summer drought in boreal forests in Finland

    Science.gov (United States)

    Gao, Y.; Markkanen, T.; Thum, T.; Aurela, M.; Lohila, A.; Mammarella, I.; Kämäräinen, M.; Hagemann, S.; Aalto, T.

    2016-01-01

    Droughts can have an impact on forest functioning and production, and even lead to tree mortality. However, drought is an elusive phenomenon that is difficult to quantify and define universally. In this study, we assessed the performance of a set of indicators that have been used to describe drought conditions in the summer months (June, July, August) over a 30-year period (1981-2010) in Finland. Those indicators include the Standardized Precipitation Index (SPI), the Standardized Precipitation-Evapotranspiration Index (SPEI), the Soil Moisture Index (SMI), and the Soil Moisture Anomaly (SMA). Herein, regional soil moisture was produced by the land surface model JSBACH of the Max Planck Institute for Meteorology Earth System Model (MPI-ESM). Results show that the buffering effect of soil moisture and the associated soil moisture memory can impact on the onset and duration of drought as indicated by the SMI and SMA, while the SPI and SPEI are directly controlled by meteorological conditions. In particular, we investigated whether the SMI, SMA and SPEI are able to indicate the Extreme Drought affecting Forest health (EDF), which we defined according to the extreme drought that caused severe forest damages in Finland in 2006. The EDF thresholds for the aforementioned indicators are suggested, based on the reported statistics of forest damages in Finland in 2006. SMI was found to be the best indicator in capturing the spatial extent of forest damage induced by the extreme drought in 2006. In addition, through the application of the EDF thresholds over the summer months of the 30-year study period, the SPEI and SMA tended to show more frequent EDF events and a higher fraction of influenced area than SMI. This is because the SPEI and SMA are standardized indicators that show the degree of anomalies from statistical means over the aggregation period of climate conditions and soil moisture, respectively. However, in boreal forests in Finland, the high initial soil moisture

  18. Fractionation of U, Th, Ra and Pb from boreal forest soils by sequential extractions

    International Nuclear Information System (INIS)

    Highlights: • A five-step sequential extraction was performed to boreal forest soil samples. • Extractions gave information about mobility and sorption of natural radionuclides. • Fractionation of U, Th, Pb and Ra varied between the sample depth and grain size. • U, Pb and Fe fractionation suggested more reducing conditions in the subsoil samples. • Ra was the only radionuclide that could be regarded as mobile. - Abstract: To determine the mobility of natural radionuclides in boreal forest soil, a five-step sequential extraction procedure was carried out on soil samples taken from various depths down to 3 m on Olkiluoto Island, Finland, where there are plans to construct a spent nuclear fuel disposal repository in the bedrock. The extracted fractions studied were exchangeable, acid-soluble, reducible, oxidizable and tightly bound. It was found that the extractability of most of the radionuclides studied was dependent on the sample grain size and depth. All the elements were concentrated in the smallest grain size samples (<0.063 mm). The extraction behaviour of Th, however, did not vary with sample depth, and only about 10% of the Th was extracted by the time of the final extraction step. Stable Pb and 210Pb, as well as Ba and Ra concentrations were strongly correlated in the extractions. Radium and Ba were leached more readily than the other elements; approximately 17% of the total Ra was found in the first fraction extracted, representing exchangeable ions. Uranium was more mobile in the topsoil horizons than in the lower horizons. In the topsoil samples, an average of 51% of the extractable U was leached in the second extraction step, representing the elements soluble in weak acids, whereas only 13% of the U in the subsoil samples was extracted in this step. This is probably due to changes in soil redox conditions lower down the soil profile. The extraction behaviour of Pb and Fe also suggests the presence of more reducing conditions in the deeper soil

  19. Microwave snow emission modeling uncertainties in boreal and subarctic environments

    Science.gov (United States)

    Roy, Alexandre; Royer, Alain; St-Jean-Rondeau, Olivier; Montpetit, Benoit; Picard, Ghislain; Mavrovic, Alex; Marchand, Nicolas; Langlois, Alexandre

    2016-03-01

    This study aims to better understand and quantify the uncertainties in microwave snow emission models using the Dense Media Radiative Theory Multi-Layer model (DMRT-ML) with in situ measurements of snow properties. We use surface-based radiometric measurements at 10.67, 19 and 37 GHz in boreal forest and subarctic environments and a new in situ data set of measurements of snow properties (profiles of density, snow grain size and temperature, soil characterization and ice lens detection) acquired in the James Bay and Umiujaq regions of Northern Québec, Canada. A snow excavation experiment - where snow was removed from the ground to measure the microwave emission of bare frozen ground - shows that small-scale spatial variability (less than 1 km) in the emission of frozen soil is small. Hence, in our case of boreal organic soil, variability in the emission of frozen soil has a small effect on snow-covered brightness temperature (TB). Grain size and density measurement errors can explain the errors at 37 GHz, while the sensitivity of TB at 19 GHz to snow increases during the winter because of the snow grain growth that leads to scattering. Furthermore, the inclusion of observed ice lenses in DMRT-ML leads to significant improvements in the simulations at horizontal polarization (H-pol) for the three frequencies (up to 20 K of root mean square error). However, representation of the spatial variability of TB remains poor at 10.67 and 19 GHz at H-pol given the spatial variability of ice lens characteristics and the difficulty in simulating snowpack stratigraphy related to the snow crust. The results also show that, in our study with the given forest characteristics, forest emission reflected by the snow-covered surface can increase the TB up to 40 K. The forest contribution varies with vegetation characteristics and a relationship between the downwelling contribution of vegetation and the proportion of pixels occupied by vegetation (trees) in fisheye pictures was found

  20. Microform-related community patterns of methane-cycling microbes in boreal Sphagnum bogs are site specific.

    Science.gov (United States)

    Juottonen, Heli; Kotiaho, Mirkka; Robinson, Devin; Merilä, Päivi; Fritze, Hannu; Tuittila, Eeva-Stiina

    2015-09-01

    Vegetation and water table are important regulators of methane emission in peatlands. Microform variation encompasses these factors in small-scale topographic gradients of dry hummocks, intermediate lawns and wet hollows. We examined methane production and oxidization among microforms in four boreal bogs that showed more variation of vegetation within a bog with microform than between the bogs. Potential methane production was low and differed among bogs but not consistently with microform. Methane oxidation followed water table position with microform, showing higher rates closer to surface in lawns and hollows than in hummocks. Methanogen community, analysed by mcrA terminal restriction fragment length polymorphism and dominated by Methanoregulaceae or 'Methanoflorentaceae', varied strongly with bog. The extent of microform-related variation of methanogens depended on the bog. Methanotrophs identified as Methylocystis spp. in pmoA denaturing gradient gel electrophoresis similarly showed effect of bog, and microform patterns were stronger within individual bogs. Our results suggest that methane-cycling microbes in boreal Sphagnum bogs with seemingly uniform environmental conditions may show strong site-dependent variation. The bog-intrinsic factor may be related to carbon availability but contrary to expectations appears to be unrelated to current surface vegetation, calling attention to the origin of carbon substrates for microbes in bogs. PMID:26220310

  1. Cloud effects from boreal forest fire smoke: evidence for ice nucleation from polarization lidar data and cloud model simulations

    International Nuclear Information System (INIS)

    Polarization lidar observations from the interior of Alaska have revealed unusual supercooled altocumulus cloud conditions in the presence of boreal forest fire smoke from local and regional fires. At temperatures of about -15 deg. C, the lidar data show ice nucleation prior to liquid cloud formation (i.e. below water saturation), as well as the occasional glaciation of the liquid layer. Thus the smoke aerosol appears to act as ice nuclei that become activated in updrafts before the liquid cloud forms, as the concentrated aqueous organic solutions are diluted sufficiently to allow them to freeze heterogeneously. This haze particle freezing process is similar to the production of cirrus ice crystals homogeneously at much colder temperatures. To test this hypothesis, cloud microphysical model simulations constrained by the measurements were performed. They indicate that this heterogeneous ice nucleation scenario can be supported by the cloud model. Although ice formation in this manner may generally act in the atmosphere, the boreal smoke particles produce an unusually dramatic effect in the lidar data. We conclude that smoke-induced ice nucleation occurs at moderate supercooled temperatures either through the effects of raised soil/dust particles embedded in the smoke droplets, coated soot aerosol or through the nucleation via certain organic solutions

  2. Tracking changes of forest carbon density following mega-fires: comparison studies in the Yellowstone National Park and Boreal Forests of Northeast China

    Science.gov (United States)

    Zhao, Feng; Huang, Chengquan; Huang, Chao; He, Hong; Zhu, Zhiliang

    2016-04-01

    Wildfires and post-fire management directly change C stored in biomass and soil pools, and can have indirect impacts on long-term C balance. Two mega fires occurred in the Yellowstone National Park (YNP) and the boreal forests of Northeast China in 1988 and 1987, respectively, making them ideal sites to examine and compare the effects of management and disturbances on regional carbon dynamics. In this study, we quantified effects of the 1988 Yellowstone fires on YNP carbon storages and fluxes. And then we tracked and modeled post-1988 forest carbon stocks change in YNP, and compared with simulation results of carbon stock changes in post-1987 fire boreal forests of Northeast China. Preliminary results show that in YNP, the mega fires in 1988 were responsible for an immediate loss of 900 g/m2 ecosystem average C density and it would take about a decade before the YNP ecosystem recover to the pre-fire average C condition. In boreal forests of Northeast China, fire reduced aboveground and belowground carbon by 230±60 g/m2 and 460±340 g/m2, respectively.

  3. Differential Atmospheric Controls on Transpiration of Boreal Trees: A Potential Factor in Pre-mature Tree Mortality in Green-Tree Retention Strategies

    Science.gov (United States)

    Bladon, K. D.; Silins, U.; Lieffers, V. J.

    2004-05-01

    Green-tree retention, a harvesting strategy that involves the preservation of isolated and interconnected patches of live trees within the boundaries of harvested areas, is assumed to emulate natural disturbance, while preserving forest canopy continuity for wildlife habitat, maintaining forest biodiversity, and many other landscape level objectives. Unfortunately, many of the retention trees die within a few years after harvesting, thus much of the desired function of these trees is lost. This research focuses on understanding the relationship between changes in micro-climate following harvesting and transpiration, potentially leading to drought-induced mortality of aspen, balsam poplar, white spruce, and white birch. Continuous measurements of whole-tree water use (sap flow) and micro-climate were taken before and after harvesting of two adjacent boreal mixedwood stands in west-central Alberta in the summer of 2003. Differences in micro-climate including radiation, air temperature, relative humidity and wind penetration into the canopy produced large differences in atmospheric moisture demand (PET) between partially harvested (green-tree retention) and undisturbed forest canopies. The variability in atmospheric conditions created large differences in sap flow velocity and transpiration rates among these four boreal species. Differential transpiration rates among species will be discussed in context of atmospheric controls on water use and drought tolerance of boreal trees with differing autecology and/or hydraulic architecture.

  4. Large-Scale Modeling Shows Little Impact of 20th-Century Changes in Temperature and Fire on the Central Canadian Boreal Forest

    Science.gov (United States)

    Bond-Lamberty, B.; Peckham, S.; Ahl, D. E.; Gower, S. T.

    2006-12-01

    Boreal forests are predicted to experience relatively large climate change (IPCC 2001), and the fire dynamics of this region may not be in equilibrium with the changing climate (Flannigan et al. 1998, Kasischke & Stocks 2000). Here we investigate how well a biogeochemical model can simulate observed 20^{th}-century changes in the structure and function of the boreal forest. Biome-BGC was used to simulate a 1000 km x 1000 km section (6-8% of the global boreal forest) of central Canadian forest at 1 km2 resolution. Historical climate, disturbance, and CO2 forcing data were used to drive the model; three dynamic vegetation types (evergreen needleleaf tree, broadleaf deciduous tree, and moss) were employed. Soil type, drainage, and other site conditions were represented as accurately as available data allowed. Assuming that the forest was at a carbon-neutral steady state in 1948, CO2 and disturbance frequency changes had small (<20 g C m-2 yr-1) and opposite effects on forest C balance by 2005; in particular, the C losses from more frequent fires were almost balanced by the C uptake of post-disturbance deciduous forests. Precipitation changes had the largest effects on C balance, with the overall forest shifting from being neutral to a small source of C, while interannual variability increased. Such a shift is smaller than can be measured using current biometric and eddy covariance techniques.

  5. Uncovering the Minor Contribution of Land-Cover Change in Upland Forests to the Net Carbon Footprint of a Boreal Hydroelectric Reservoir.

    Science.gov (United States)

    Dessureault, Pierre-Luc; Boucher, Jean-François; Tremblay, Pascal; Bouchard, Sylvie; Villeneuve, Claude

    2015-07-01

    Hydropower in boreal conditions is generally considered the energy source emitting the least greenhouse gas per kilowatt-hour during its life cycle. The purpose of this study was to assess the relative contribution of the land-use change on the modification of the carbon sinks and sources following the flooding of upland forested territories to create the Eastmain-1 hydroelectric reservoir in Quebec's boreal forest using Carbon Budget Model of the Canadian Forest Sector. Results suggest a carbon sink loss after 100 yr of 300,000 ± 100,000 Mg CO equivalents (COe). A wildfire sensitivity analysis revealed that the ecosystem would have acted as a carbon sink as long as carbon flux estimate resulted in emissions of 4 ± 2 g COe kWh as a contribution to the carbon footprint calculation, one-eighth what was obtained in a recent study that used less precise and less sensitive estimates. Consequently, this study significantly reduces the reported net carbon footprint of this reservoir and reveals how negligible the relative contribution of the land-use change in upland forests to the total net carbon footprint of a hydroelectric reservoir in the boreal zone can be. PMID:26437092

  6. Mirror image hydrocarbons from Tropical and Boreal forests

    Directory of Open Access Journals (Sweden)

    J. Williams

    2007-01-01

    Full Text Available Monoterpenes, emitted in large quantities by trees to attract pollinators and repel herbivores, can exist in mirror image forms called enantiomers. In this study such enantiomeric pairs have been measured in ambient air over extensive forest ecosystems in South America and northern Europe. For the dominant monoterpene, α-pinene, the (−-form was measured in large excess over the (+-form over the Tropical rainforest, whereas the reverse was observed over the Boreal forest. Interestingly, over the Tropical forest (−-α-pinene did not correlate with its own enantiomer, but correlated well with isoprene. The results indicate a remarkable ecosystem scale enantiomeric fingerprint and a nexus between the biosphere and atmosphere.

  7. Nitrogen balance of a boreal Scots pine forest

    Directory of Open Access Journals (Sweden)

    J. F. J. Korhonen

    2013-02-01

    Full Text Available The productivity of boreal forests is considered to be limited by low nitrogen (N availability. Increased atmospheric N deposition has altered the functioning and N cycling of these N-sensitive ecosystems by increasing the availability of reactive nitrogen. The most important components of N pools and fluxes were measured in a boreal Scots pine stand in Hyytiälä, Southern Finland. The measurements at the site allowed direct estimations of nutrient pools in the soil and biomass, inputs from the atmosphere and outputs as drainage flow and gaseous losses from two micro-catchments. N was accumulating in the system, mainly in woody biomass, at a rate of 7 kg N ha−1 yr−1. Nitrogen input as atmospheric deposition was 7.4 kg N ha−1 yr−1. Dry deposition and organic N in wet deposition contributed over half of the inputs in deposition. Total outputs were 0.4 kg N ha−1 yr−1, the most important outputs being N2O emission to the atmosphere and organic N flux in drainage flow. Nitrogen uptake and retranslocation were equally important sources of N for plant growth. Most of the assimilated N originated from decomposition of organic matter, and the fraction of N that could originate directly from deposition was about 30%. In conclusion, atmospheric N deposition fertilizes the site considerably, but there are no signs of N saturation. Further research is needed to estimate soil N2 fluxes (emission and fixation, which may amount up to several kg N ha−1 yr−1.

  8. Methane dynamics in different boreal ewline lake types

    Directory of Open Access Journals (Sweden)

    S. Juutinen

    2008-09-01

    Full Text Available This study explores the variability in concentrations of dissolved CH4 and annual flux estimates in the pelagic zone in a statistically defined sample of 207 lakes in Finland. The lakes were situated representatively in the boreal zone, where the mean annual air temperature ranges from −2.8 to 5.9°C. We examined how lake CH4 dynamics related to regional lake types assessed according to the EU water framework directive. Ten lake types were defined on the basis of water chemistry, color, and size. Lakes were sampled for dissolved CH4 concentrations four times per year, at four different depths at the deepest point of each lake. We found that CH4 concentrations and fluxes to the atmosphere tended to be high in nutrient rich calcareous lakes, and that the shallow lakes had the greatest surface water concentrations. CH4 content in the hypolimnion was related to oxygen and nutrient concentrations, and lake depth or area. The surface water CH4 concentration was related to the depth or area of lake. Methane close to the bottom can be viewed as proxy of lake status in terms of frequency of anoxia and nutrient levels. Median CH4 release from randomly selected lakes was 45 mmol m−2 a−1. Shallow lakes had the highest median CH4 effluxes, with the clear shallow lake type having the smallest median. Our data, combined with other studies, suggest that lake surface area could be used for an approximation of CH4 release from lakes. Shallow small lakes common in boreal and arctic landscapes may have disproportional significance with respect to CH4 release.

  9. Differences in fire regimes and fire-climate feedbacks in North American and Eurasian boreal forests.

    Science.gov (United States)

    Rogers, B. M.; Randerson, J. T.; Soja, A. J.

    2012-12-01

    Boreal forests contribute 9% of current annual fire emissions and contain nearly 40% of the world's terrestrial carbon stocks. Temperatures are projected to increase by the greatest magnitudes in high latitudes and lead to increased frequencies of forest fires. However, because of variations in climate and species-driven forest structure, fire regimes of North American and Eurasian boreal forests are distinctly different. These differences are generally not accounted for in global models. We quantified variations in fire and burn severity between the two continents using MODIS fire radiative power, differenced Normalized Burn Ratio, and spring albedo. These metrics suggest that Eurasian boreal fires are on average less than half as severe as those in North America. We examine how boreal forest fires may respond to 21st century climate change using the Community Land Model, and consider how these regimes may feed back to climate through fire-emitted aerosols, greenhouse gas fluxes, and land surface characteristics.

  10. Differentiating moss from higher plants is critical in studying the carbon cycle of the boreal biome.

    Science.gov (United States)

    Yuan, Wenping; Liu, Shuguang; Dong, Wenjie; Liang, Shunlin; Zhao, Shuqing; Chen, Jingming; Xu, Wenfang; Li, Xianglan; Barr, Alan; Andrew Black, T; Yan, Wende; Goulden, Mike L; Kulmala, Liisa; Lindroth, Anders; Margolis, Hank A; Matsuura, Yojiro; Moors, Eddy; van der Molen, Michiel; Ohta, Takeshi; Pilegaard, Kim; Varlagin, Andrej; Vesala, Timo

    2014-01-01

    The satellite-derived normalized difference vegetation index (NDVI), which is used for estimating gross primary production (GPP), often includes contributions from both mosses and vascular plants in boreal ecosystems. For the same NDVI, moss can generate only about one-third of the GPP that vascular plants can because of its much lower photosynthetic capacity. Here, based on eddy covariance measurements, we show that the difference in photosynthetic capacity between these two plant functional types has never been explicitly included when estimating regional GPP in the boreal region, resulting in a substantial overestimation. The magnitude of this overestimation could have important implications regarding a change from a current carbon sink to a carbon source in the boreal region. Moss abundance, associated with ecosystem disturbances, needs to be mapped and incorporated into GPP estimates in order to adequately assess the role of the boreal region in the global carbon cycle. PMID:24967601

  11. Vulnerability of the boreal forest to climate change: are managed forests more susceptible?

    International Nuclear Information System (INIS)

    This paper postulates that forests dominated by younger seral stages are less vulnerable to climate change that those composed of mature and overmature stands. To support this analysis, an overview of expected changes in climate conditions was provided. Expected changes include higher maximum temperatures, higher minimum temperatures and a decrease in periods of intense cold and fewer frost days; reduction in the diurnal temperature range; an increase in the apparent heat index; greater numbers of intense precipitation; and, increased risk of drought associated with air mass movements. A comparison between conditions in a managed forest mosaic and natural forests was made, with managed forests differing due to efforts to regulate the age structure. The inversion in the age structure of forest mosaics creates significant changes in structural characteristics and composition, including greater hardwood components and more even-aged stands. It was concluded that in Canada, managed boreal forests are younger and have less black spruce and more hardwoods and fir, making younger forests less vulnerable to fire and more amenable to fire control due to increased accessibility. It was also noted that because of their relative youth, managed forests are more vulnerable to regeneration failure and that managed forests with more balsam fir and trembling aspen are at greater risk for insect outbreaks. In addition, wind throw, a threat to older forests, is not significant in managed forests. 15 refs., 1 tab., 2 figs

  12. The oxidation capacity of the boreal forest: first simulated reactivities of O3 and NO3

    Directory of Open Access Journals (Sweden)

    D. Mogensen

    2014-12-01

    Full Text Available Using the 1D atmospheric chemistry–transport model SOSAA, we have investigated the atmospheric reactivity of a boreal forest ecosystem during the HUMPPA-COPEC-10 campaign (summer 2010, at SMEAR II in Southern Finland. For the very first time, we present vertically resolved model simulations of the NO3- and O3-reactivity (R together with the modelled and measured reactivity of OH. We find that OH is the most reactive oxidant (R~3 s−1 followed by NO3 (R~0.07 s−1 and O3 (R~2 × 10−5 s−1. The missing OH-reactivity was found to be large in accordance with measurements (~65% as would be expected from the chemical subset described in the model. The accounted OH radical sinks were inorganic compounds (~41%, mainly due to reaction with CO, emitted monoterpenes (~14% and oxidised biogenic volatile organic compounds (~44%. The missing reactivity is expected to be due to unknown biogenic volatile organic compounds and their photoproducts, indicating that the true main sink of OH is not expected to be inorganic compounds. The NO3 radical was found to react mainly with primary emitted monoterpenes (~60% and inorganic compounds (~37%, including NO2. NO2 is, however, only a temporary sink of NO3 under the conditions of the campaign and does not affect the NO3 concentration. We discuss the difference between instantaneous and steady state reactivity and present the first boreal forest steady state lifetime of NO3 (113 s. O3 almost exclusively reacts with inorganic compounds (~91%, mainly NO, but also NO2 during night and less with primary emitted sesquiterpenes (~6% and monoterpenes (~3%. When considering the concentration of the oxidants investigated, we find that O3 is the oxidant that is capable of removing pollutants fastest. As part of this study, we developed a simple empirical parameterisation for conversion of measured spectral irradiance into actinic flux. Further, the meteorological conditions were evaluated using radiosonde observations and

  13. Spatial variations in the trophic structure of soil animal communities in boreal forests of Pechora-Ilych Nature Reserve

    Science.gov (United States)

    Goncharov, A. A.; Khramova, E. Yu.; Tiunov, A. V.

    2014-05-01

    Soil animal communities and detrital food webs are spatially compartmentalized. In old-growth boreal forests the dynamics of dominating plant species forms a considerable heterogeneity of edaphic conditions in the soil layer. We demonstrate a strong difference in total and relative abundance of main trophic groups of soil macrofauna in four microsites, i.e. under tree crowns, in gaps, in mounds and in pits created by fallen spruce trees. The variation in the functional structure of soil animal communities is likely related to different availability of key energy resources (leaf litter, roots and root deposits) in the microsites studied. However, results of the stable isotope analysis suggest that mobile litter-dwelling predators occupy very similar trophic positions in different microsites. The compartmentalization of soil invertebrate communities caused by the vegetation-induced mosaic of edaphic conditions seemingly does not lead to spatial isolation of local food webs that are integrated at the top trophic levels.

  14. The effect of altered macroclimate on N-fixation by boreal feather mosses

    OpenAIRE

    Gundale, Michael J.; Wardle, David A.; Nilsson, Marie-Charlotte

    2012-01-01

    Plant productivity is predicted to increase in boreal forests owing to climate change, but this may depend on whether N inputs from biological N-fixation also increases. We evaluated how alteration of climatic factors affects N input from a widespread boreal N-fixer, i.e. cyanobacteria associated with the feather moss Pleurozium schreberi. In each of 10 forest stands in northern Sweden, we established climate-change plots, including a control (ambient climate) plot and three plots experiencin...

  15. Modeling the effects of organic nitrogen uptake by plants on the carbon cycling of boreal ecosystems

    Directory of Open Access Journals (Sweden)

    Q. Zhu

    2013-08-01

    Full Text Available Boreal forest and tundra are the major ecosystems in the northern high latitudes in which a large amount of carbon is stored. These ecosystems are nitrogen-limited due to slow mineralization rate of the soil organic nitrogen. Recently, abundant field studies have found that organic nitrogen is another important nitrogen supply for boreal ecosystems. In this study, we incorporated a mechanism that allowed boreal plants to uptake small molecular amino acids into a process-based biogeochemical model, the Terrestrial Ecosystem Model (TEM, to evaluate the impact of organic nitrogen uptake on ecosystem carbon cycling. The new version of the model was evaluated at both boreal forest and tundra sites. We found that the modeled organic nitrogen uptake accounted for 36–87% of total nitrogen uptake by plants in tundra ecosystems and 26–50% for boreal forests, suggesting that tundra ecosystem might have more relied on the organic form of nitrogen than boreal forests. The simulated monthly gross ecosystem production (GPP and net ecosystem production (NEP tended to be larger with the new version of the model since the plant uptake of organic nitrogen alleviated the soil nitrogen limitation especially during the growing season. The sensitivity study indicated that the most important factors controlling the plant uptake of organic nitrogen were the maximum root uptake rate (Imax and the radius of the root (r0 in our model. The model uncertainty due to uncertain parameters associated with organic nitrogen uptake at tundra ecosystem was larger than at boreal forest ecosystems. This study suggests that considering the organic nitrogen uptake by plants is important to boreal ecosystem carbon modeling.

  16. The influence of boreal forest fires on the global distribution of non-methane hydrocarbons

    OpenAIRE

    Lewis, A. C.; Evans, M J; J. R. Hopkins; S. Punjabi; Read, K A; Andrews, S; Moller, S. J.; Carpenter, L. J.; J. D. Lee; A. R. Rickard; Palmer, P. I.; M. Parrington

    2012-01-01

    Boreal forest fires are a significant source of chemicals to the atmosphere including numerous non-methane hydrocarbons (NMHCs). We report airborne measurements of NMHCs, acetone and methanol from > 500 whole air samples collected over Eastern Canada, including interception of several different boreal biomass burning plumes. From these and concurrent measurements of carbon monoxide (CO) we derive fire emission ratios for 29 different species relative to the emission of CO. These range from...

  17. The role of colloidal matter in transfer of chemical elements in the boreal zone (European Russia)

    OpenAIRE

    Ilina, Svetlana

    2012-01-01

    The objective of this thesis was to study element speciation and migration in the boreal environments (Karelia and Central Russia). Specific goals were to i) characterize the molecular weight distribution of trace elements and organic matter (OM) in various types of natural waters, ii) reveal the TE colloidal forms dependence in the continuum soil solution - bog - stream - feeding and terminal lakes in the surface waters of boreal watersheds, and iii) quantify the dependence of stable and rad...

  18. Traditional use of medicinal plants in the boreal forest of Canada: review and perspectives

    OpenAIRE

    Uprety Yadav; Asselin Hugo; Dhakal Archana; Julien Nancy

    2012-01-01

    Abstract Background The boreal forest of Canada is home to several hundred thousands Aboriginal people who have been using medicinal plants in traditional health care systems for thousands of years. This knowledge, transmitted by oral tradition from generation to generation, has been eroding in recent decades due to rapid cultural change. Until now, published reviews about traditional uses of medicinal plants in boreal Canada have focused either on particular Aboriginal groups or on restricte...

  19. Annual cycle of volatile organic compound exchange between a boreal pine forest and the atmosphere

    OpenAIRE

    Rantala, P.; Aalto, J; Taipale, R.; T. M. Ruuskanen; J. Rinne

    2015-01-01

    Long-term flux measurements of volatile organic compounds (VOC) over boreal forests are rare, although the forests are known to emit considerable amounts of VOCs into the atmosphere. Thus, we measured fluxes of several VOCs and oxygenated VOCs over a Scots-pine-dominated boreal forest semi-continuously between May 2010 and December 2013. The VOC profiles were obtained with a proton transfer reaction mass spectrometry, and the fluxes were calculated using vertical concentrati...

  20. Annual cycle of volatile organic compound exchange between a boreal pine forest and the atmosphere

    OpenAIRE

    Rantala, P.; Aalto, J; Taipale, R.; T. M. Ruuskanen; J. Rinne

    2015-01-01

    Long-term flux measurements of volatile organic compounds (VOC) over boreal forests are rare, although the forests are known to emit considerable amounts of VOCs into the atmosphere. Thus, we measured fluxes of several VOCs and oxygenated VOCs over a Scots pine dominated boreal forest semi-continuously between May 2010 and December 2013. The VOC profiles were obtained with a proton-transfer-reaction mass-spectrometry, and the fluxes were calculated using vertical concentrati...

  1. The Effect of Pollution on Newly-Formed Particle Composition in Boreal Forest

    Science.gov (United States)

    Vaattovaara, Petri

    2010-05-01

    Petri Vaattovaara (1), Tuukka Petäjä (2), Jorma Joutsensaari (1), Pasi Miettinen (1), Boris Zaprudin (1,6), Aki Kortelainen (1), Juha Heijari (3,7), Pasi Yli-Pirilä (3), Pasi Aalto (2), Doug R. Worsnop (4), and Ari Laaksonen(1,5) (1) University of Eastern Finland, Finland (2) University of Helsinki, Finland (3) University of Eastern Finland, Finland (4) Aerodyne Research Inc., USA (5) Finnish Meteorological Institute, Finland (6) Currently at University of Turku, Finland (7) Currently at Maritime Research Centre, Finland Email address of the Corresponding author: Petri.Vaattovaara@uef.fi The geographical extent of the tropical, temperate and boreal forests is about 30% of the Earth's land surface. Those forests are located around the world in different climate zones effecting widely on atmospheric composition via new particle formation. The Boreal forests solely cover one third of the forests extent and are one of the largest vegetation environments, forming a circumpolar band throughout the northern hemisphere continents, with a high potential to affect climate processes [1]. In order to more fully understand the possible climatic effects of the forests, the properties of secondary organic aerosols (SOA) in varying conditions (e.g. a change in meteorological parameters or in the concentrations of biogenic and antropogenic trace gases) need to be better known. In this study, we applied the UFO-TDMA (ultrafine organic tandem differential mobility analyzer [2]) and the UFH-TDMA (ultrafine hygroscopicity tandem differential mobility analyzer [3]) methods parallel to shed light on the evolution of the nucleation and Aitken mode particle compositions (via physic-chemical properties) at a virgin boreal forest site in varying conditions. The measurements were carried out at Hyytiälä forest station in Northern Europe (Finland) during 15 spring nucleation events. We also carried out a statistical analysis using linear correlations in order to explain the variability in

  2. Fire severity influences the response of soil microbes to a boreal forest fire

    Science.gov (United States)

    Holden, Sandra R.; Rogers, Brendan M.; Treseder, Kathleen K.; Randerson, James T.

    2016-03-01

    Wildfire activity is projected to increase in boreal forests as a result of climate warming. The consequences of increased wildfire activity for soil carbon (C) storage in boreal forests may depend on the sensitivity of soil microbes to fire severity, but microbial responses to boreal forest fire severity are not well known. Here, we combine remote sensing of fire severity and field sampling to characterize the response of soil microbial biomass per g soil, microbial respiration of CO2 per g soil, and fungal groups to fire severity in a boreal forest ecosystem. We used remote sensing measurements of differenced normalized burn ratio from Landsat as a measure of fire severity. Our results demonstrate that fire severity controls soil microbial responses to boreal forest fires. In comparison to unburned stands, burned stands had a 52% and 56% reduction in soil microbial biomass and basal respiration, respectively. Within burned stands, we found that microbial biomass and basal respiration significantly declined with increasing fire severity. In addition, mycorrhizal taxa and basidiomycetes displayed particularly low tolerances for severe fire. Although wildfires result in the immediate loss of soil C, our study provides evidence that decreases in microbial biomass and respiration following high severity fires may reduce the capacity of the soil microbial community to decompose soil C over longer time scales. Therefore, models of C cycle responses to climate warming may need to represent the sensitivity of microbial biomass and fungal community composition to fire severity in boreal forests.

  3. Interannual variability of Antarctic Oscillation and its influence on East Asian climate during boreal winter and spring

    Institute of Scientific and Technical Information of China (English)

    FAN; Ke; WANG; Huijun

    2006-01-01

    The interannual variability of Antarctic Oscillation (AAO) and its influence on East Asian climate during both boreal winter and spring are addressed. The results show that the positive AAO anomaly decreases the cold activity over East Asia during both boreal winter and spring. AAO-related barotropic meridional teleconnection from Antarctic to Arctic is found through analysis of mean meridional circulations. This meridional teleconnection is remarkable over Eurasia during boreal winter and over the Pacific Ocean during boreal spring. The results also show that zonal mean zonal wind at high latitudes in Southern Hemisphere has well positive correlation with that of Eurasia during boreal winter and has negative correlation with Pacific North American teleconnection (PNA) during boreal spring, which again display the meridional teleconnection. Thus, local meridional teleconnection is a possible linkage for interaction of circulations at mid-high latitudes between both hemispheres.

  4. De weekdieren van de Nederlandse brakwatergebieden (Mollusca)

    OpenAIRE

    Kuijper, W.J.

    2000-01-01

    The molluscs of the brackish waters in the Netherlands (Mollusca) The Netherlands is a river delta rich in brackish waters. The organisms in these waters need to be adapted to extreme conditions, especially large fluctuations in chlorinity. However, several species occur optimally in this habitat. In this paper a review is presented of the molluscs living in brackish waters in the Netherlands. All available data from literature, collections, literature and databanks were compiled for this cau...

  5. Trophic cascades, invasive species and body-size hierarchies interactively modulate climate change responses of ecotonal temperate–boreal forest

    OpenAIRE

    Lee E. Frelich; Peterson, Rolf O; Dovčiak, Martin; Peter B. Reich; Vucetich, John A.; Eisenhauer, Nico

    2012-01-01

    As the climate warms, boreal tree species are expected to be gradually replaced by temperate species within the southern boreal forest. Warming will be accompanied by changes in above- and below-ground consumers: large moose (Alces alces) replaced by smaller deer (Odocoileus virginianus) above-ground, and small detritivores replaced by larger exotic earthworms below-ground. These shifts may induce a cascade of ecological impacts across trophic levels that could alter the boreal to temperate f...

  6. Factors affecting the sorption of cesium in a nutrient-poor boreal bog

    International Nuclear Information System (INIS)

    135Cs is among the most important radionuclides in the long-term safety assessments of spent nuclear fuel, due to its long half-life of 2.3 My and large inventory in spent nuclear fuel. Batch sorption experiments were conducted to evaluate the sorption behavior of radiocesium (134Cs) in the surface moss, peat, gyttja, and clay layers of 7-m-deep profiles taken from a nutrient-poor boreal bog. The batch distribution coefficient (Kd) values of radiocesium increased as a function of sampling depth. The highest Kd values, with a geometric mean of 3200 L/kg dry weight (DW), were observed in the bottom clay layer and the lowest in the 0.5–1.0 m peat layer (50 L/kg DW). The maximum sorption in all studied layers was observed at a pH between 7 and 9.5. The in situ Kd values of 133Cs in surface Sphagnum moss, peat and gyttja samples were one order of magnitude higher than the Kd values obtained using the batch method. The highest in situ Kd values (9040 L/kg DW) were recorded for the surface moss layer. The sterilization of fresh surface moss, peat, gyttja and clay samples decreased the sorption of radiocesium by 38%, although the difference was not statistically significant. However, bacteria belonging to the genera Pseudomonas, Paenibacillus, Rhodococcus and Burkholderia isolated from the bog were found to remove radiocesium from the solution under laboratory conditions. The highest biosorption was observed for Paenibacillus sp. V0-1-LW and Pseudomonas sp. PS-0-L isolates. When isolated bacteria were added to sterilized bog samples, the removal of radiocesium from the solution increased by an average of 50% compared to the removal recorded for pure sterilized peat. Our results demonstrate that the sorption of radiocesium in the bog environment is dependent on pH and the type of the bog layer and that common environmental bacteria prevailing in the bog can remove cesium from the solution phase. - Highlights: • pH and the type of the bog layer affect the sorption

  7. Modelling and measurement of solar induced fluorescence in a boreal scots pine canopy

    Science.gov (United States)

    Nichol, C. J.; Drolet, G.; Atherton, J.; Wade, T. J.; Porcar-Castell, A.; Levula, J.; Nikinmaa, E.; Vesala, T.

    2012-12-01

    Terrestrial sun induced chlorophyll fluorescence (Fs) is emitted by chlorophyll molecules in the photosystems of higher plants. The signal originates from the photosynthetic machinery and is thus expected to respond to changes in environmental conditions such as light and physiological stress. This therefore makes Fs an attractive tool to provide insight into a plants photosynthetic performance over traditional reflectance based approaches utilised in vegetation remote sensing applications. A number of Fs retrieval methods from optical data have been documented and these share a common basis; that the fractional depth of the Fraunhofer lines decreases due to infilling by solar induced fluorescence (Fs). Here we presents results from two (linked) studies that demonstrates the challenge of retrieving Fs from, firstly, continuous irradiance and radiance measurements collected over a boreal canopy from a custom built continuously operating optical system, and secondly, we present a coupled physiological-radiative transfer model that predicts changes in the apparent reflectance of a leaf, due to chlorophyll fluorescence that occur on timescales of seconds to minutes. The biochemical model is based on a detailed model of the dynamics of the fate of absorbed light energy through photosystem II. The radiative transfer component is derived from empirically obtained fluorescence excitation-emission matrices and the PROSPECT leaf model. A Markov Chain Monte Carlo (MCMC) algorithm was used to optimise biochemical model parameters by fitting model simulations of transient chlorophyll fluorescence to measured reflectance spectra. The model successfully simulated the transient fluorescence decay curve and reproduced yield estimates for photochemical and non-photochemical quenching when validated against an independent data-set. The biochemical model is driven solely by incident radiation, to scale to the canopy and to use the model on trans-seasonal time scales the effects of

  8. An assessment of fire occurrence regime and performance of Canadian fire weather index in south central Siberian boreal region

    Directory of Open Access Journals (Sweden)

    T. Chu

    2014-07-01

    Full Text Available Wildfire is the dominant natural disturbance in Eurasian boreal region, which acts as a major driver of the global carbon cycle. An effectiveness of wildfire management requires suitable tools for fire prevention and fire risk assessment. This study aims to investigate fire occurrence patterns in relation to fire weather conditions in the remote south central Siberia region. The Canadian Fire Weather Index derived from large-scale meteorological reanalysis data was evaluated with respects to fire regimes during 14 consecutive fire seasons in south central Siberian environment. All the fire weather codes and indices, including the Fine Fuel Moisture Code (FFMC, the Duff Moisture Code (DMC, the Drought Code (DC, the Buildup Index (BUI, the Initial Spread Index (ISI, and the Fire Weather Index (FWI, were highly reflected inter-annual variation of fire activity in south central Siberia. Even though human-caused fires were major events in Russian boreal forest including south central Siberia, extreme fire years were strongly correlated with ambient weather conditions (e.g. Arctic Oscillation, air temperature, relative humidity and wind, showing by in-phase (or positive linear relationship and significant wavelet coherence between fire activity and DMC, ISI, BUI, and FWI. Time series observation of 14 fire seasons showed that there was an average of about 3 months lags between the peaks of fire weather conditions and fire activity, which should take into account when using coarse scale fire weather indices in the assessment of fire danger in the study area. The results are expected to contribute to a better reconstruction and prediction of fire activity using large-scale reanalysis data in remote regions in which station data are very few.

  9. A Geographic Perspective on Factors Controlling Post-Fire Succession in Boreal Black Spruce Forests in Western North America

    Science.gov (United States)

    Kasischke, E. S.; Kane, E. S.; Genet, H.; Turetsky, M. R.; ODonnell, J. A.; Hoy, E.; Barrett, K.; Baltzer, J. L.

    2014-12-01

    Recent changes to climate and the fire regime have resulted in a number of distinct changes to patterns of post-fire succession in the boreal forest region of western North America. In interior Alaska and Yukon, these responses include a shift from spruce to deciduous dominated forests in black spruce forests that experienced exposure of mineral soils from deep burning of surface organic soils, as well as low seedling recruitment in white spruce forests as a result of moisture stress. In this presentation, we will use a physical geography framework to analyze factors controlling low seedling recruitment in recently burned black spruce forests in Alaska. This approach allows for understanding how changes in the biologic components of black spruce forest ecosystems (e.g., biogeography) are controlled by factors related to geomorphology and climate over multiple spatial and temporal scales. In particular, this framework will be used to examine how the interactions between fire, climate, topography and soil texture influence pre-fire and post-fire permafrost conditions, which interact to have a strong influence on variations in soil moisture. In turn, recent changes to climate combined with variations in soil moisture controlled by differences in permafrost conditions (ground ice content, active layer thickness) can be used to explain variations in post-fire seedling recruitment in black spruce forests, where low recruitment is occurring on the sites with the driest soils. In addition, we will examine the need for further research in other boreal forest regions of western North America where the presence of pine species (jack and lodgepole) that are absent in Alaska, as well as differences in soils and permafrost conditions, are likely resulting in additional patterns of post-fire succession as a result of recent changes to climate and the fire regime.

  10. Biomass production efficiency controlled by management in temperate and boreal ecosystems

    Science.gov (United States)

    Campioli, M.; Vicca, S.; Luyssaert, S.; Bilcke, J.; Ceschia, E.; Chapin, F. S., III; Ciais, P.; Fernández-Martínez, M.; Malhi, Y.; Obersteiner, M.; Olefeldt, D.; Papale, D.; Piao, S. L.; Peñuelas, J.; Sullivan, P. F.; Wang, X.; Zenone, T.; Janssens, I. A.

    2015-11-01

    Plants acquire carbon through photosynthesis to sustain biomass production, autotrophic respiration and production of non-structural compounds for multiple purposes. The fraction of photosynthetic production used for biomass production, the biomass production efficiency, is a key determinant of the conversion of solar energy to biomass. In forest ecosystems, biomass production efficiency was suggested to be related to site fertility. Here we present a database of biomass production efficiency from 131 sites compiled from individual studies using harvest, biometric, eddy covariance, or process-based model estimates of production. The database is global, but dominated by data from Europe and North America. We show that instead of site fertility, ecosystem management is the key factor that controls biomass production efficiency in terrestrial ecosystems. In addition, in natural forests, grasslands, tundra, boreal peatlands and marshes, biomass production efficiency is independent of vegetation, environmental and climatic drivers. This similarity of biomass production efficiency across natural ecosystem types suggests that the ratio of biomass production to gross primary productivity is constant across natural ecosystems. We suggest that plant adaptation results in similar growth efficiency in high- and low-fertility natural systems, but that nutrient influxes under managed conditions favour a shift to carbon investment from the belowground flux of non-structural compounds to aboveground biomass.

  11. Response of the boreal forest ecosystem to climatic change and its silvicultural implications

    Energy Technology Data Exchange (ETDEWEB)

    Kellomaeki, S.; Haenninen, H.; Karjalainen, T. [Joensuu Univ. (Finland). Faculty of Forestry] [and others

    1996-12-31

    During the next 100 years, the mean annual temperature is expected to be 1-6 deg C higher than at present. It is also expected to be accompanied by a lengthening of the thermal growing season and increased precipitation. Consequently, climatic change will increase the uncertainty of the management of forest ecosystems in the future. In this context, this research project aimed to outline the ecological and silvicultural implications of climatic change with regard to (1) how the expected climatic change might modify the functioning and structure of the boreal forest ecosystem, and (2) how the silvicultural management of the forest ecosystem should be modified in order to maintain sustainable forest yield under changing climatic conditions. The experimental component of the project concerned first the effect that elevating temperature and elevating concentration of atmospheric carbon have on the ontogenetic development of Scots pine (Pinus sylvestris L) and on the subsequent increase in frost damage during winter. The second part of the study looked the effect of elevating temperature and elevating concentration of atmospheric carbon on the growth of Scots pine through photosynthesis, respiration, transpiration, nutrient supply, and changes in crown structure. This experiment was utilised in several subprojects of the overall project

  12. The influence of boreal spring Arctic Oscillation on the subsequent winter ENSO in CMIP5 models

    Science.gov (United States)

    Chen, Shangfeng; Chen, Wen; Yu, Bin

    2016-06-01

    This study examines the influence of boreal spring Arctic Oscillation (AO) on the subsequent winter El Niño-Southern Oscillation (ENSO) using 15 climate model outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Results show that, out of the 15 CMIP5 models, CCSM4 and CNRM-CM5 can well reproduce the significant AO-ENSO connection. These two models capture the observed spring AO related anomalous cyclone (anticyclone) over the subtropical western-central North Pacific, and westerly (easterly) winds over the tropical western-central Pacific. In contrast, the spring AO-related anomalous circulation over the subtropical North Pacific is insignificant in the other 13 models, and the simulations in these models cannot capture the significant influence of the spring AO on ENSO. Further analyses indicate that the performance of the CMIP5 simulations in reproducing the AO-ENSO connection is related to the ability in simulating the spring North Pacific synoptic eddy intensity and the spring AO's Pacific component. Strong synoptic-scale eddy intensity results in a strong synoptic eddy feedback on the mean flow, leading to strong cyclonic circulation anomalies over the subtropical North Pacific, which contributes to a significant AO-ENSO connection. In addition, a strong spring AO's Pacific component and associated easterly wind anomalies to its south may provide more favorable conditions for the development of spring AO-related cyclonic circulation anomalies over the subtropical North Pacific.

  13. Nitrous oxide uptake rates in boreal coniferous forests are associated with soil characteristics

    Science.gov (United States)

    Siljanen, Henri; Biasi, Christina; Martikainen, Pertti

    2014-05-01

    Nitrous oxide (N2O) is a strong greenhouse gas and a significant contributor to the destruction of the ozone layer. The radiative forcing of N2O is considered to be 320 more efficient than carbon dioxide.The major portion of global N2O is emitted from agricultural soils. There are studies suggesting that N2O has also a sink in forest soils. However there is relatively limited knowledge on factors controlling N2O consumption in forest soils. Hence N2O consumption was studied in boreal coniferous forests having different forest cover, soil chemical and physical structure and land-use history. The N2O consumption was measured by static chamber technique in the field across spatio-seasonal sampling design. Typical and atypical denitrifiers were quantified with nosZ functional gene marker. Additionally chemical and physical environmental parameters were analyzed to link N2O flux, microbial community and composition of soils. Nitrous oxide uptake could be associated with specific ecosystem and environmental conditions. Soil physical structure and land-use history were shown to be prior factors determining the strength of the uptake rate.

  14. Trade-Offs in Resource Allocation Among Moss Species Control Decomposition in Boreal Peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Turetsky, M. R.; Crow, S. E.; Evans, R. J.; Vitt, D. H.; Wieder, R. K.

    2008-01-01

    We separated the effects of plant species controls on decomposition rates from environmental controls in northern peatlands using a full factorial, reciprocal transplant experiment of eight dominant bryophytes in four distinct peatland types in boreal Alberta, Canada. Standard fractionation techniques as well as compound-specific pyrolysis molecular beam mass spectrometry were used to identify a biochemical mechanism underlying any interspecific differences in decomposition rates. We found that over a 3-year field incubation, individual moss species and not micro-environmental conditions controlled early stages of decomposition. Across species, Sphagnum mosses exhibited a trade-off in resource partitioning into metabolic and structural carbohydrates, a pattern that served as a strong predictor of litter decomposition. Decomposition rates showed a negative co-variation between species and their microtopographic position, as species that live in hummocks decomposed slowly but hummock microhabitats themselves corresponded to rapid decomposition rates. By forming litter that degrades slowly, hummock mosses appear to promote the maintenance of macropore structure in surface peat hummocks that aid in water retention. Many northern regions are experiencing rapid climate warming that is expected to accelerate the decomposition of large soil carbon pools stored within peatlands. However, our results suggest that some common peatland moss species form tissue that resists decomposition across a range of peatland environments, suggesting that moss resource allocation could stabilize peatland carbon losses under a changing climate.

  15. Seasonal variation of CCN concentrations and aerosol activation properties in boreal forest

    Directory of Open Access Journals (Sweden)

    S.-L. Sihto

    2011-12-01

    Full Text Available As a part of EUCAARI activities, the annual cycle of cloud condensation nuclei (CCN concentrations and critical diameter for cloud droplet activation as a function of supersaturation were measured using a CCN counter and a HTDMA (hygroscopicity tandem differential mobility analyzer at SMEAR II station, Hyytiälä, Finland. The critical diameters for CCN activation were estimated from (i the measured CCN concentration and particle size distribution data, and (ii the hygroscopic growth factors by applying κ-Köhler theory, in both cases assuming an internally mixed aerosol. The critical diameters derived by these two methods were in good agreement with each other. The effect of new particle formation on the diurnal variation of CCN concentration and critical diameters was studied. New particle formation was observed to increase the CCN concentrations by 70–110%, depending on the supersaturation level. The average value for the κ-parameter determined from hygroscopicity measurements was κ = 0.18 and it predicted well the CCN activation in boreal forest conditions in Hyytiälä. The derived critical diameters and κ-parameter confirm earlier findings with other methods, that aerosol particles at CCN sizes in Hyytiälä are mostly organic, but contain also more hygrosopic, probably inorganic salts like ammonium sulphate, making the particles more CCN active than pure secondary organic aerosol.

  16. Aged boreal biomass burning aerosol size distributions from BORTAS 2011

    Science.gov (United States)

    Sakamoto, K. M.; Allan, J. D.; Coe, H.; Taylor, J. W.; Duck, T. J.; Pierce, J. R.

    2014-09-01

    Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number size-distributions in climate model inventories lead to uncertainties in the CCN concentrations and forcing estimates derived from these models. The BORTAS-B measurement campaign was designed to sample boreal biomass-burning outflow over Eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size-distribution of aged biomass-burning emissions (aged ∼1-2 days) from boreal wildfires in Northwestern Ontario. The composite median size-distribution yields a single dominant accumulation mode with Dpm = 230 nm (number-median diameter), σ = 1.7, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA / ΔCO) along the path of Flight b622 show values of 0.05-0.18 μg m-3 ppbv-1 with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA production/evaporation within the aged plume over the sampling period. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution corresponding to the BORTAS-B aged size-distributions. The model was restricted to coagulation and dilution processes based on the insignificant net OA production/evaporation derived from the ΔOA / ΔCO enhancement ratios. We estimate that the fresh-plume median diameter was in the range of 59-94 nm with modal widths in the range of 1.7-2.8 (the ranges are due to uncertainty in the entrainment rate). Thus, the size of the freshly emitted particles is relatively unconstrained due to the uncertainties in the

  17. Aged Boreal Biomass Burning Size Distributions from Bortas 2011

    Science.gov (United States)

    Pierce, J. R.; Sakamoto, K.; Allan, J. D.; Coe, H.; Taylor, J.; Duck, T.

    2014-12-01

    Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are strong functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number size-distributions in climate model inventories lead to uncertainties in the CCN concentrations and forcing estimates derived from these models. The BORTAS-B measurement campaign was designed to sample boreal biomass-burning outflow over Eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size-distribution of aged biomass-burning emissions (aged ~ 1.5 - 2 days) from boreal wildfires in Northwestern Ontario. The composite median size-distribution yields a single dominant accumulation mode with Dpm = 232 nm, σ = 1.7, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA/ΔCO) along the path of Flight b622 show values of 0.08-0.18 μg m-3 ppbv-1 with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA production/evaporation within the aged plume over the sampling period. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution and flux corresponding to the BORTAS-B aged size-distributions. The model was restricted to coagulation and dilution processes only based on the insignificant net OA production/evaporation derived from the ΔOA/ΔCO enhancement ratios. Depending on the, we estimate that the fresh-plume median diameter was in the range of 59-94 nm with modal widths in the range of 1.7-2.8. Thus, the size of the freshly emitted particles is somewhat unconstrained due to the uncertainties in the plume dilution rates.

  18. Arctic Boreal Vulnerability Experiment (ABoVE) Science Cloud

    Science.gov (United States)

    Duffy, D.; Schnase, J. L.; McInerney, M.; Webster, W. P.; Sinno, S.; Thompson, J. H.; Griffith, P. C.; Hoy, E.; Carroll, M.

    2014-12-01

    The effects of climate change are being revealed at alarming rates in the Arctic and Boreal regions of the planet. NASA's Terrestrial Ecology Program has launched a major field campaign to study these effects over the next 5 to 8 years. The Arctic Boreal Vulnerability Experiment (ABoVE) will challenge scientists to take measurements in the field, study remote observations, and even run models to better understand the impacts of a rapidly changing climate for areas of Alaska and western Canada. The NASA Center for Climate Simulation (NCCS) at the Goddard Space Flight Center (GSFC) has partnered with the Terrestrial Ecology Program to create a science cloud designed for this field campaign - the ABoVE Science Cloud. The cloud combines traditional high performance computing with emerging technologies to create an environment specifically designed for large-scale climate analytics. The ABoVE Science Cloud utilizes (1) virtualized high-speed InfiniBand networks, (2) a combination of high-performance file systems and object storage, and (3) virtual system environments tailored for data intensive, science applications. At the center of the architecture is a large object storage environment, much like a traditional high-performance file system, that supports data proximal processing using technologies like MapReduce on a Hadoop Distributed File System (HDFS). Surrounding the storage is a cloud of high performance compute resources with many processing cores and large memory coupled to the storage through an InfiniBand network. Virtual systems can be tailored to a specific scientist and provisioned on the compute resources with extremely high-speed network connectivity to the storage and to other virtual systems. In this talk, we will present the architectural components of the science cloud and examples of how it is being used to meet the needs of the ABoVE campaign. In our experience, the science cloud approach significantly lowers the barriers and risks to organizations

  19. Studies of microwave scattering and canopy architecture for boreal forests

    Science.gov (United States)

    Lockhart, G. Lance; Gogineni, S. P.

    1994-01-01

    Our primary objectives during the last year have been to develop a helicopter-borne radar system for measuring microwave backscatter from vegetation and to use this system to study the characteristics of backscatter from the boreal forest. Our research is aimed at refining the current microwave models and using these improvements for more accurate interpretation of SAR data. SAR data are very useful for monitoring the boreal forest region because of the microwave signal's ability to penetrate clouds and to see at night. Meeting these objectives involves several stages of development. The first stage is the design and implementation of a frequency-modulated continuous-wave (FM-CW) radar system with the capability of measuring backscatter at three frequencies and four polarizations at each frequency. These requirements necessitate a twelve-channel radar system. Using three frequencies is advantageous because it allows us to look at different parts of the canopy. For instance, the lower frequency signal penetrates deeper into the canopy and allows us to see the ground while the high frequency signal is scattered more by the leaves and needles and typically does not penetrate to the floor of the forest. We designed the radar starting with the antenna system. We then developed the intermediate frequency (IF) and radio frequency (RF) sections of the radar. Also, the need to collect data from twelve channels during each flight line presented a complex data acquisition problem that we solved by using a high-speed data acquisition board. After construction, the radar was tested at the lab. We performed extensive testing of the IF and RF systems of the radar during this time. Once we were satisfied with the operation of the radar it was shipped to Canada for use in the second intensive field campaign (IFC-2) from July 16 - August 8, 1994. During IFC-2, we collected backscatter data over the experimental sites in the southern study area (SSA). Additionally, we used a ground

  20. Tropical influence on boreal summer mid-latitude stationary waves

    Energy Technology Data Exchange (ETDEWEB)

    Douville, Herve [Meteo-France/CNRM-GAME, Toulouse (France); CNRM/GMGEC/VDR, Toulouse (France); Bielli, S.; Deque, M.; Tyteca, S.; Voldoire, A. [Meteo-France/CNRM-GAME, Toulouse (France); Cassou, C. [CNRS-Cerfacs, Toulouse (France); Hall, N.M.J. [CNES/LEGOS, Toulouse (France)

    2011-11-15

    While organized tropical convection is a well-known source of extratropical planetary waves, state-of-the-art climate models still show serious deficiencies in simulating accurately the atmospheric response to tropical sea surface temperature (SST) anomalies and the associated teleconnections. In the present study, the remote influence of the tropical atmospheric circulation is evaluated in ensembles of global boreal summer simulations in which the Arpege-Climat atmospheric General Circulation Model (GCM) is nudged towards 6-h reanalyses. The nudging is applied either in the whole tropical band or in a regional summer monsoon domain. Sensitivity tests to the experimental design are first conducted using prescribed climatological SST. They show that the tropical relaxation does not improve the zonal mean extratropical climatology but does lead to a significantly improved representation of the mid-latitude stationary waves in both hemispheres. Low-pass filtering of the relaxation fields has no major effect on the model response, suggesting that high-frequency tropical variability is not responsible for extratropical biases. Dividing the nudging strength by a factor 10 only decreases the magnitude of the response. Model errors in each monsoon domain contribute to deficiencies in the model's mid-latitude climatology, although an exaggerated large-scale subsidence in the central equatorial Pacific appears as the main source of errors for the representation of stationary waves in the Arpege-Climat model. Case studies are then conducted using either climatological or observed SST. The focus is first on summer 2003 characterized by a strong and persistent anticyclonic anomaly over western Europe. This pattern is more realistic in nudging experiments than in simulations only driven by observed SST, especially when the nudging domain is centred over Central America. Other case studies also show a significant tropical forcing of the summer mid-latitude stationary waves

  1. Large contribution of boreal upland forest soils to a catchment-scale CH4 balance in a wet year

    Science.gov (United States)

    Lohila, Annalea; Aalto, Tuula; Aurela, Mika; Hatakka, Juha; Tuovinen, Juha-Pekka; Kilkki, Juho; Penttilä, Timo; Vuorenmaa, Jussi; Hänninen, Pekka; Sutinen, Raimo; Viisanen, Yrjö; Laurila, Tuomas

    2016-03-01

    Upland forest soils affect the atmospheric methane (CH4) balance, not only through the soil sink but also due to episodic high emissions in wet conditions. We measured methane fluxes and found that during a wet fall the forest soil turned from a CH4 sink into a large source for several months, while the CH4 emissions from a nearby wetland did not increase. When upscaled to the whole catchment area the contribution of forests amounted to 60% of the annual CH4 emission from the wetlands, while in a normal year the forest soil consumes 10% of the wetland emission. The period of high upland soil emission was also captured by the nearby atmospheric concentration measurement station. Since the land cover within the catchment is representative of larger regions, our findings imply that upland forests in the boreal zone constitute an important part in the global CH4 cycle not previously accounted for.

  2. The bud break process and its variation among local populations of boreal black spruce.

    Science.gov (United States)

    Rossi, Sergio; Bousquet, Jean

    2014-01-01

    Phenology of local populations can exhibit adaptations to the current environmental conditions resulting from a close interaction between climate and genotype. The bud break process and its variations among populations were analyzed in greenhouse by monitoring the growth resumption in black spruce [Picea mariana (Mill.) BSP] seedlings originating from seeds of five stands across the closed boreal forest in Quebec, Canada. Bud break lasted 15 days and occurred earlier and quicker in northern provenances. Provenance explained between 10.2 and 32.3% of the variance in bud break, while the families accounted for a smaller but still significant part of the variance. The late occurrence of one phenological phase corresponded to a delayed occurrence of the others according to linear relationships. A causal model was proposed in the form of a chain of events with each phase of bud break being related to the previous and successive one, while no link was observed between non-adjacent phases. The adaptation of black spruce populations along the latitudinal gradient points toward a strategy based on rapid physiological processes triggered by temperature increase inducing high metabolic activity. The variation observed in bud break reflects an evolutionary trade-off between maximization of security and taking advantage of the short growing season. This work provides evidence of the phenological adaptations of black spruce to its local environmental conditions while retaining sizeable genetic diversity within populations. Because of the multigenic nature of phenology, this diversity should provide some raw material for adaptation to changing local environmental conditions. PMID:25389430

  3. Uptake, turnover and transport of radiocaesium in boreal forest ecosystems

    International Nuclear Information System (INIS)

    The study was mainly addressed to aspects on the redistribution of the Chernobyl fallout within and output from a coniferous forest ecosystem. The only detected pathway for Cs to exit the ecosystem was via discharge from mires. About 40% of the deposition on mires discharged via stream water during the snow-melt 1986. The residual fraction discharged at an annual rate of 30% from water saturated fractions and about 2% from drier fractions of the studied mire. No loss of Cs from ridges and moraine slopes to ground water was detected. The main transfer from the canopy to the forest floor occurred during the first year. The estimated transfer from throughfall and litterfall during May 1986 to May 1996 was 50% of the estimated total deposition in the ecosystem. The contribution from herbivory was estimated to 1% of the deposition. In 1987 the fraction of Cs that was retained in the above ground parts of a Scots pine stand was only 4%. The Cs intercepted in mosses and lichens were slowly transferred to the litter and humus layers. Cs in vegetation with green parts above ground during the fallout decreased rapidly during the first vegetation season The ranking in Cs of the studied plants was fireweed 137Cs. Moose meat, berries and mushrooms produced in the boreal region will give rise to a small but significant internally absorbed dose to man during several years. 57 refs, 9 figs, 5 tabs

  4. The behaviour of radioactive caesium in a boreal forest ecosystem

    International Nuclear Information System (INIS)

    The distribution of radioactive caesium (Cs-134 and Cs-137) in a boreal forest ecosystem is studied with focus in the dynamics of the turnover in, and loss from, the system. Measurements of the distribution in soil and vegetation, as well as the loss of radioactive caesium by run-off from a catchment, constitute the basis for an analysis of the caesium budget in the system. Comparisons of the distribution of 'old' Cs-137, i.e. originating from fallout due to the atmospheric nuclear weapons test, and that due to deposition after the accident in Chernobyl 1986 are used for extrapolations to future situations concerning transport of Cs-137 via the food chains over berries and moose to man. The exposure in a long term perspective due to the average intake of Cs-137 in the Swedish population by consumption of meat, milk, and milk products (i.e. of an agricultural origin) is compared to that due to ingestion of the forest products: berries (bilberry, lingonberries, and cloudberries) and moose meat. (au) (34 refs.)

  5. Project SKEG : re-establishing peatlands in Alberta boreal forests

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, C. [Shell Canada Ltd., Calgary, AB (Canada)

    2008-04-01

    Scientific protocols for oil and gas remediation projects in the peatlands region of Alberta's boreal forests were discussed. Peatlands in Alberta occupy an estimated 103,000 km{sup 2} of the province, and act as water storage reservoirs in addition to filtering precipitation as its moves into groundwater. While providing a habitat for a variety of animals, peatlands are a significant carbon sink. The gravel roads and well site pads placed in Alberta's peatlands are having an impact on the peatland ecosystem, and in some cases oil and gas activities have reduced the carbon sink capacity of peatlands by 50 per cent. This paper provided details of a project planned by Shell Canada to reclaim peatlands disturbed by oil and gas activities. The project aimed to re-establish major species after a period of 3 years while establishing a ground layer mat over a period of 10 years with peatland flora similar to its surroundings. Optimal levels of the well pads will be identified, and pH level and water flow into the pad will be monitored and controlled. Appropriate plants will be selected for the paludifying reclamation process. Amendments for enhancing the plant establishment and organic matter accumulation will also be investigated. It was concluded that the project is expected to take place in 2008. 1 fig.

  6. Effects of ionizing radiation on the boreal forest

    International Nuclear Information System (INIS)

    The Field-Irradiator-Gamma (FIG) project chronically exposed a section of the boreal forest to ionizing radiation by placing a 137Cs source on tope of a 20-m tower at a forest site in southeastern Manitoba. The irradiation continued from 1973 to 1986 and the forest was exposed to radiological dose rates ranging from 65 mGy.h-1 to 0.005 mGy.h-1 along a gradient extending 500 m from the source. The irradiation killed the tree canopy close to the irradiator, resulting in the formation of a herbaceous zone of vegetation at high dose rates. After 14 years of irradiation, some tree species were still being affected at dose rates as low as about 1 mGy.h-1. The data gathered at the FIG site can be used to identify radiological dose rates that forest communities can tolerate. This information allows decisions to be made concerning guidelines for protection of the general environment from radionuclide emissions from various anthropogenic sources, such as nuclear reactors and uranium tailings. This report reviews the previous data collected at the FIG site during the pre-irradiation and irradiation phases and the methodology used to establish a baseline for future comparisons. Permanently marked sampling plots are a particular strength to the study, whereby researchers can compare the present forest community with that measured during the past 25 years. (author). 53 refs., 6 tabs., 22 figs

  7. Multi-Sensor Characterization of the Boreal Forest: Initial Findings

    Science.gov (United States)

    Reith, Ernest; Roberts, Dar A.; Prentiss, Dylan

    2001-01-01

    Results are presented in an initial apriori knowledge approach toward using complementary multi-sensor multi-temporal imagery in characterizing vegetated landscapes over a site in the Boreal Ecosystem-Atmosphere Study (BOREAS). Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and Airborne Synthetic Aperture Radar (AIRSAR) data were segmented using multiple endmember spectral mixture analysis and binary decision tree approaches. Individual date/sensor land cover maps had overall accuracies between 55.0% - 69.8%. The best eight land cover layers from all dates and sensors correctly characterized 79.3% of the cover types. An overlay approach was used to create a final land cover map. An overall accuracy of 71.3% was achieved in this multi-sensor approach, a 1.5% improvement over our most accurate single scene technique, but 8% less than the original input. Black spruce was evaluated to be particularly undermapped in the final map possibly because it was also contained within jack pine and muskeg land coverages.

  8. Methane production and consumption in grassland and boreal ecosystems

    Science.gov (United States)

    Schimel, David S.; Burke, Ingrid C.; Johnston, Carol; Pastor, John

    1994-01-01

    The objectives of the this project were to develop a mechanistic understanding of methane production and oxidation suitable for incorporation into spatially explicit models for spatial extrapolation. Field studies were undertaken in Minnesota, Canada, and Colorado to explore the process controls over the two microbial mediated methane transformations in a range of environments. Field measurements were done in conjunction with ongoing studies in Canada (the Canadian Northern Wetlands Projects: NOWES) and in Colorado (The Shortgrass Steppe Long Term Ecological Research Project: LTER). One of the central hypotheses of the proposal was that methane production should be substrate limited, as well as being controlled by physical variables influencing microbial activity (temperature, oxidation status, and pH). Laboratory studies of peats from Canada and Minnesota (Northern and Southern Boreal) were conducted with amendments of a methanogenic substrate at multiple temperatures and at multiple pHs (the latter by titrating samples). The studies showed control by substrate, pH, and temperature in order in anaerobic samples. Field and laboratory manipulations of natural plant litter, rather than an acetogenic substrate, showed similarly large effects. The studies concluded that substrate is an important control over methanogenesis, that substrate availability in the field is closely coupled to the chemistry of the dominant vegetation influencing its decomposition rate, that most methane is produced from recent plant litter, and that landscape changes in pH are an important control, highly correlated with vegetation.

  9. Age of vegetation simulated by Boreal ALFRESCO for the state of Alaska. Dataset generated in 2010. NAD83, Alaska Albers projection, http://spatialreference.org/ref/epsg/3338/

    Data.gov (United States)

    Arctic Landscape Conservation Cooperative — These rasters represent output from the Boreal ALFRESCO (Alaska Frame Based Ecosystem Code) model. Boreal ALFRESCO operates on an annual time step, in a landscape...

  10. Traditional use of medicinal plants in the boreal forest of Canada: review and perspectives

    Directory of Open Access Journals (Sweden)

    Uprety Yadav

    2012-01-01

    Full Text Available Abstract Background The boreal forest of Canada is home to several hundred thousands Aboriginal people who have been using medicinal plants in traditional health care systems for thousands of years. This knowledge, transmitted by oral tradition from generation to generation, has been eroding in recent decades due to rapid cultural change. Until now, published reviews about traditional uses of medicinal plants in boreal Canada have focused either on particular Aboriginal groups or on restricted regions. Here, we present a review of traditional uses of medicinal plants by the Aboriginal people of the entire Canadian boreal forest in order to provide comprehensive documentation, identify research gaps, and suggest perspectives for future research. Methods A review of the literature published in scientific journals, books, theses and reports. Results A total of 546 medicinal plant taxa used by the Aboriginal people of the Canadian boreal forest were reported in the reviewed literature. These plants were used to treat 28 disease and disorder categories, with the highest number of species being used for gastro-intestinal disorders, followed by musculoskeletal disorders. Herbs were the primary source of medicinal plants, followed by shrubs. The medicinal knowledge of Aboriginal peoples of the western Canadian boreal forest has been given considerably less attention by researchers. Canada is lacking comprehensive policy on harvesting, conservation and use of medicinal plants. This could be explained by the illusion of an infinite boreal forest, or by the fact that many boreal medicinal plant species are widely distributed. Conclusion To our knowledge, this review is the most comprehensive to date to reveal the rich traditional medicinal knowledge of Aboriginal peoples of the Canadian boreal forest. Future ethnobotanical research endeavours should focus on documenting the knowledge held by Aboriginal groups that have so far received less attention

  11. CH4 and N2O dynamics in the boreal forest–mire ecotone

    OpenAIRE

    Tupek, B.; K. Minkkinen; J. Pumpanen; Vesala, T; Nikinmaa, E.

    2015-01-01

    In spite of advances in greenhouse gas research, the spatiotemporal CH4 and N2O dynamics of boreal landscapes remain challenging, e.g., we need clarification of whether forest–mire transitions are occasional hotspots of landscape CH4 and N2O emissions during exceptionally high and low ground water level events. In our study, we tested the differences and drivers of CH4 and N2O dynamics of forest/mire types in field conditions along the soil moisture gradient of the fo...

  12. Fourteen Years of Pond Monitoring in Boreal Plain, northern Alberta, Canada: The effects of climate variability and harvesting practices

    Science.gov (United States)

    Abnizova, A.; Devito, K. J.; Petrone, R. M.

    2013-12-01

    Western Boreal forest of Canada is experiencing rapid increase in rates of cumulative impacts of disturbance for resource extraction, climate change and forest fires. To understand their sensitivity and response to multi-decadal natural and anthropogenic disturbances a long-term (1998-2013) and extensive pond ecosystem monitoring has been conducted on the Boreal Plains at the Utikuma Region Study Area (URSA) (56o N, 115o W). Hydrological, chemical and nutrient data were collected along a forest-peatland-pond transect in a paired catchment aspen harvest study in the area underlain by fine-grained till moraines glacial deposits. The aims of this study were (1) to identify the main characteristics in pond hydrologic regime, specifically water level dynamics, both seasonally and between years; (2) to identify factors controlling variation in measured hydro-chemistry and nutrients; and (3) to provide evidence on how water quality conditions in the ponds are changing on long (multi-year to decadal) time scales in response to harvesting practices and climatic trends during wet and dry cycles. No difference in pond or catchment hydrologic and hydro-chemical response was observed between harvested and reference sites pre- or post- harvesting. Wetland and pond waters were not affected by the harvesting practices due to lack of hydrologic connectivity between pond and forest systems. The hydrologic relationship between forestlands and open-water wetlands is a response in their water balance differences driven by their storage characteristics. Temporal trends in ponds' water levels, chemical and nutrient concentrations during the 14 year record were most closely related to relative connectivity to groundwater systems and flow direction in response to climatic cycles and vegetation water use and were the most useful parameters for characterizing duration and type of connectivity during wet and dry cycles. Using empirical relationships from such long-term monitoring, this study

  13. Carbon stock and carbon turnover in boreal and temperate forests - Integration of remote sensing data and global vegetation models

    Science.gov (United States)

    Thurner, Martin; Beer, Christian; Carvalhais, Nuno; Forkel, Matthias; Tito Rademacher, Tim; Santoro, Maurizio; Tum, Markus; Schmullius, Christiane

    2016-04-01

    Long-term vegetation dynamics are one of the key uncertainties of the carbon cycle. There are large differences in simulated vegetation carbon stocks and fluxes including productivity, respiration and carbon turnover between global vegetation models. Especially the implementation of climate-related mortality processes, for instance drought, fire, frost or insect effects, is often lacking or insufficient in current models and their importance at global scale is highly uncertain. These shortcomings have been due to the lack of spatially extensive information on vegetation carbon stocks, which cannot be provided by inventory data alone. Instead, we recently have been able to estimate northern boreal and temperate forest carbon stocks based on radar remote sensing data. Our spatially explicit product (0.01° resolution) shows strong agreement to inventory-based estimates at a regional scale and allows for a spatial evaluation of carbon stocks and dynamics simulated by global vegetation models. By combining this state-of-the-art biomass product and NPP datasets originating from remote sensing, we are able to study the relation between carbon turnover rate and a set of climate indices in northern boreal and temperate forests along spatial gradients. We observe an increasing turnover rate with colder winter temperatures and longer winters in boreal forests, suggesting frost damage and the trade-off between frost adaptation and growth being important mortality processes in this ecosystem. In contrast, turnover rate increases with climatic conditions favouring drought and insect outbreaks in temperate forests. Investigated global vegetation models from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT, are able to reproduce observation-based spatial climate - turnover rate relationships only to a limited extent. While most of the models compare relatively well in terms of NPP, simulated

  14. Cross-scale ensemble predictions of dissolved organic carbon dynamics in a network of contrasting boreal forest streams

    Science.gov (United States)

    Oni, S. K.; Futter, M.; Teutschbein, C.; Laudon, H.

    2013-12-01

    Climate is an important driver of dissolved organic carbon (DOC) dynamics in boreal forest catchments. Understanding climate impacts and plausible future trajectories of DOC requires significant modelling efforts. While numerous biogeochemical models have been used to understand climate related controls on DOC, they are inherently uncertain as no single model represents all relevant processes. Here we present an ensemble modelling approach using outputs from 15 regional climate models (RCM) to project future soil temperature and stream flows which, in turn, are used to drive two models of surface water DOC. INCA-C is a process-based model of DOC operating at a catchment scale and RIM is a hillslope-scale empirical model. Models were applied to Svartberget, a pristine boreal catchment in northern Sweden. Svartberget contains streams draining forest (C2), mire (C4) and a mixture of forest and mire landscape elements (C7). RCM outputs suggest that Svartberget will experience warmer, wetter conditions in the future with temperature and precipitation increasing by up to 5oC and 36% respectively. Warmer air temperatures are projected to lead to a warming in soil temperature of approximately 2oC. While there is some uncertainty in the expected change in annual runoff (-14 to 29%), all RCMs agreed on a shift in spring melt from May to April. Both RIM (NS 0.52 - 0.62) and INCA-C (NS 0.49 - 0.50) performed well in representing present day stream [DOC]. However, they differ in their future projections. INCA-C and RIM model projections were in close agreement for C2, suggesting increases in stream [DOC] of about 20%. However, INCA-C projected a decrease (-31%) while RIM projected minimal changes (-5 to +6%) in [DOC] in C4. Both models projected an increase in [DOC] of 13% in C7. There was greater uncertainty in RIM-estimated DOC fluxes than those simulated with INCA-C. This study shows the importance of using an ensemble of climate projections and multiple models applied to a

  15. Peatland use and transport of particulate organic matter in boreal headwater catchments

    Science.gov (United States)

    Marttila, Hannu; Karjalainen, Satu-Maaria; Nieminen, Mika; Kløve, Bjørn

    2014-05-01

    Peatland use can cause increased transport of particulate organic matter (POM) causing deteriorated water quality and especially siltation of stream beds. Even though topic has gained major attention among stakeholders it has received only minor efforts to solve the main sources and properties of transported particles. The development of effective management practices and evaluation of purification efficiency demands understanding of the sources of particulate matter in peat dominated catchments with various land uses and hydrological conditions. The objectives of this study were: (1) to determinate physical properties of POM in headwater brooks affected by different peatland uses, and; (2) to identity the sources of transported material by using sediment fingerprinting methods. For this purpose, two headwater catchments under peat extraction and peatland forestry land uses with 8 sampling points were monitored for 2 years using time integrated suspended sediment samplers. Data was completed by gap samples from 50 other headwater locations with different upstream land uses: pristine, peatland forestry and peat extraction. For the sources analysis, disturbed topsoil, stream bed sediment, banks of ditches and brooks, algae and various vegetation types were identified as the potential sediment sources. Stable isotopes (δ13C, δ15N) and C/N ratio were analyzed to discriminate between the possible sources. Results are further scaled against different land uses, landscape elements and seasonal hydrological conditions in headwaters. This paper presents the preliminary results from a two year study aiming to show various patterns in transport of POM in boreal headwater catchments. Due to strong land-water relationship in headwaters, further information on the properties of particles is needed to assess the downstream impacts of land use.

  16. The characteristics of sea fog with different airflow over the Huanghai Sea in boreal spring

    Institute of Scientific and Technical Information of China (English)

    HUANG Jian; WANG Xin; ZHOU Wen; HUANG Huijun; WANG Dongxiao; ZHOU Faxiu

    2010-01-01

    Using the observations from ICOADS datasets and contemporaneous NCEP/NCAR reanalysis datasets during 1960-2002, the study classifies the airflows in favor of sea fog over the Huang-hai (Yellow) Sea in boreal spring (April-May) with the method of trajectory analysis, and analyzes the changes of proportions of warm and cold sea fogs along different paths of airflow. According to the heat balance equation, we investigate the relationships between the marine meteorological conditions and the proportion of warm and cold sea fog along different airflow paths. The major results are summarized as follows. (1) Sea fogs over the Huanghai Sea in spring are not only warm fog but also cold fog. The proportion of warm fog only accounts for 44% in April, while increases as high as 57% in May. (2) Four primary airflow paths leading to spring sea fog are identified. They are originated from the northwest, east, southeast and southwest of the Huanghai Sea, respectively. The occurrence ratios of the warm sea fog along the east and southeast airflow paths are high of 55% and 70%, while these along the southwest and northwest airflow paths are merely 17.9% and 50%. (3) The key physical processes governing the warm/cold sea fog are heat advection transport, longwave radiation cooling at fog top, solar shortwave warming and latent heat flux between air-sea interfaces. (4) The characteristics of sea fog along the four airflow paths relate closely to the conditions of water vapor advection, and the vertical distribution of relative humidity.

  17. Patterns of cross-continental variation in tree seed mass in the Canadian Boreal Forest.

    Directory of Open Access Journals (Sweden)

    Jushan Liu

    Full Text Available Seed mass is an adaptive trait affecting species distribution, population dynamics and community structure. In widely distributed species, variation in seed mass may reflect both genetic adaptation to local environments and adaptive phenotypic plasticity. Acknowledging the difficulty in separating these two aspects, we examined the causal relationships determining seed mass variation to better understand adaptability and/or plasticity of selected tree species to spatial/climatic variation. A total of 504, 481 and 454 seed collections of black spruce (Picea mariana (Mill. B.S.P., white spruce (Picea glauca (Moench Voss and jack pine (Pinus banksiana Lamb across the Canadian Boreal Forest, respectively, were selected. Correlation analyses were used to determine how seed mass vary with latitude, longitude, and altitude. Structural Equation Modeling was used to examine how geographic and climatic variables influence seed mass. Climatic factors explained a large portion of the variation in seed mass (34, 14 and 29%, for black spruce, white spruce and jack pine, respectively, indicating species-specific adaptation to long term climate conditions. Higher annual mean temperature and winter precipitation caused greater seed mass in black spruce, but annual precipitation was the controlling factor for white spruce. The combination of factors such as growing season temperature and evapotranspiration, temperature seasonality and annual precipitation together determined seed mass of jack pine. Overall, sites with higher winter temperatures were correlated with larger seeds. Thus, long-term climatic conditions, at least in part, determined spatial variation in seed mass. Black spruce and Jack pine, species with relatively more specific habitat requirements and less plasticity, had more variation in seed mass explained by climate than did the more plastic species white spruce. As traits such as seed mass are related to seedling growth and survival, they

  18. Quantification of nitrous oxide (N2O) uptake in boreal forest soils by combining isotopic and microbial approaches

    Science.gov (United States)

    Welti, Nina; Siljanen, Henri; Biasi, Christina; Martikainen, Pertti

    2015-04-01

    The amount of nitrous oxide (N2O) produced during denitrification is highly regulated by the function of the last reductase enzyme (nitrous oxide reductase; nosZ) which is known to be inhibited by oxygen, low pH and low temperature, which are typical characteristics of boreal peatlands and some forest soils. Denitrification can be a sink for N2O, if the last step of the process is very efficient. Generally, the N2O sink potential of soils is poorly constrained; while uptake rates were often observed in field studies, the data was rejected as analytical errors or artifacts. This led to the question: when and by which mechanisms does N2O uptake occur in natural boreal forests? In order to answer this question, we established a 15N2O tracer experiment where the production of 15N2 and consumption of 15N2O were quantified in aerobic and anaerobic conditions followed by abundance analyses of genes and transcripts. The laboratory incubations were complemented with molecular approaches which linked the N2O dynamics with individual microbial species and transcriptomics. The abundance of denitrifying functional genes and gene transcripts reducing nitrous oxide (nosZ) were quantified throughout the experiment with sacrificial sampling in order to solve the role of typical and atypical denitrifying populations on N2O consumption. For this study, a Finnish boreal spruce forest and peatland were selected where previous field measurements have revealed negative N2O fluxes (i.e. N2O uptake). Soil horizons were selected in both the organic layer and uppermost mineral soil layer and in the peat layers 0-10 cm and 10-20 cm, where oxygen is limited and N2O uptake occurs at the field scale. 15N-N2O (99 AT %) was added to an initial N2O concentration of 1.7 ppm. All soils were flushed with 100% helium prior to the N2O addition to ensure that the NO3 stocks were reduced, leaving the added N2O as the sole activator of N2O uptake and primary N source. Aerobic N2O uptake was quantified in

  19. Fire cycle of the Canada's boreal region and its potential response to global change

    Institute of Scientific and Technical Information of China (English)

    ZHANG Quan-fa; CHEN Wen-jun

    2007-01-01

    Interactions of fire cycle and plant species' reproductive characteristics could determine vegetation distribution pattern of a landscape. In Canada's boreal region, fire cycles before the Little Ice Age (c. 1850s) ranged from 30-130 years and 25-234 years afterwards until the settlement period (c. 1930s) when longer fire cycles occurred in response to climatic change and human interference. Analysis indicated that fire cycles were correlated with growing season (April-October) temperature and precipitation departure from the 1961-1990 normal, varying by regions. Assuming that wildfires will respond to future warming similar to the manner during the past century, an assessment using climatic change scenarios CGCM1, CGCM2 and HadCM2 indicates fire cycles would divert to a range of 80-140 years in the west taiga shield, more than 700 years for the east boreal shield and east taiga shield, and 300-400 years for the boreal plains in 2050.

  20. Contribution of vegetation and water table on isoprene emission from boreal peatland microcosms

    DEFF Research Database (Denmark)

    Tiiva, Päivi; Faubert, Patrick; Räty, Sanna;

    2009-01-01

    Boreal peatlands are substantial sources of isoprene, a reactive hydrocarbon. However, it is not known how much mosses, vascular plants and peat each contribute to isoprene emission from peatlands. Furthermore, there is no information on the effects of declining water table depth on isoprene...... emission in these naturally wet ecosystems, although water table is predicted to decline due to climate warming. We studied the relative contribution of mosses vs. vascular plants to isoprene emission in boreal peatland microcosms in growth chambers by removing either vascular vegetation or both vascular...... vegetation and mosses. The microcosms represented wet hollows and dry hummocks of a boreal ombrotrophic bog. A water table drawdown treatment was applied to the hollows with naturally high water table. The mean (±SE) isoprene emission from hummocks with intact vegetation, 30 ± 6 µg m-2 h-1, was decreased by...

  1. Assessment of the APCC Coupled MME Suite in Predicting the Distinctive Climate Impacts of Two Flavors of ENSO during Boreal Winter

    Science.gov (United States)

    Jeong, Hye-In; Lee, Doo Young; Karumuri, Ashok; Ahn, Joong-Bae; Lee, June-Yi; Luo, Jing-Jia; Schemm, Jae-Kyung E.; Hendon, Harry H.; Braganza, Karl; Ham, Yoo-Geun

    2012-01-01

    Forecast skill of the APEC Climate Center (APCC) Multi-Model Ensemble (MME) seasonal forecast system in predicting two main types of El Nino-Southern Oscillation (ENSO), namely canonical (or cold tongue) and Modoki ENSO, and their regional climate impacts is assessed for boreal winter. The APCC MME is constructed by simple composite of ensemble forecasts from five independent coupled ocean-atmosphere climate models. Based on a hindcast set targeting boreal winter prediction for the period 19822004, we show that the MME can predict and discern the important differences in the patterns of tropical Pacific sea surface temperature anomaly between the canonical and Modoki ENSO one and four month ahead. Importantly, the four month lead MME beats the persistent forecast. The MME reasonably predicts the distinct impacts of the canonical ENSO, including the strong winter monsoon rainfall over East Asia, the below normal rainfall and above normal temperature over Australia, the anomalously wet conditions across the south and cold conditions over the whole area of USA, and the anomalously dry conditions over South America. However, there are some limitations in capturing its regional impacts, especially, over Australasia and tropical South America at a lead time of one and four months. Nonetheless, forecast skills for rainfall and temperature over East Asia and North America during ENSO Modoki are comparable to or slightly higher than those during canonical ENSO events.

  2. boreal forest when timber prices and tree growth are stochastic

    Institute of Scientific and Technical Information of China (English)

    Timo Pukkala

    2015-01-01

    Background:Decisions on forest management are made under risk and uncertainty because the stand development cannot be predicted exactly and future timber prices are unknown. Deterministic calculations may lead to biased advice on optimal forest management. The study optimized continuous cover management of boreal forest in a situation where tree growth, regeneration, and timber prices include uncertainty. Methods:Both anticipatory and adaptive optimization approaches were used. The adaptive approach optimized the reservation price function instead of fixed cutting years. The future prices of different timber assortments were described by cross-correlated auto-regressive models. The high variation around ingrowth model was simulated using a model that describes the cross-and autocorrelations of the regeneration results of different species and years. Tree growth was predicted with individual tree models, the predictions of which were adjusted on the basis of a climate-induced growth trend, which was stochastic. Residuals of the deterministic diameter growth model were also simulated. They consisted of random tree factors and cross-and autocorrelated temporal terms. Results:Of the analyzed factors, timber price caused most uncertainty in the calculation of the net present value of a certain management schedule. Ingrowth and climate trend were less significant sources of risk and uncertainty than tree growth. Stochastic anticipatory optimization led to more diverse post-cutting stand structures than obtained in deterministic optimization. Cutting interval was shorter when risk and uncertainty were included in the analyses. Conclusions:Adaptive optimization and management led to 6%–14%higher net present values than obtained in management that was based on anticipatory optimization. Increasing risk aversion of the forest landowner led to earlier cuttings in a mature stand. The effect of risk attitude on optimization results was small.

  3. Riparian zone controls on base cation concentrations in boreal streams

    Directory of Open Access Journals (Sweden)

    J. L. J. Ledesma

    2013-01-01

    Full Text Available Forest riparian zones are a major in control of surface water quality. Base cation (BC concentrations, fluxes, and cycling in the riparian zone merit attention because of increasing concern of negative consequences for re-acidification of surface waters from future climate and forest harvesting scenarios. We present a two-year study of BC and silica (Si flow-weighted concentrations from 13 riparian zones and 14 streams in a boreal catchment in northern Sweden. The Riparian Flow-Concentration Integration Model (RIM was used to estimate riparian zone flow-weighted concentrations and tested to predict the stream flow-weighted concentrations. Spatial variation in BC and Si concentrations as well as in flow-weighted concentrations was related to differences in Quaternary deposits, with the largest contribution from lower lying silty sediments and the lowest contribution from wetland areas higher up in the catchment. Temporal stability in the concentrations of most elements, a remarkably stable Mg / Ca ratio in the soil water and a homogeneous mineralogy suggest that the stable patterns found in the riparian zones are a result of distinct mineralogical upslope groundwater signals integrating the chemical signals of biological and chemical weathering. Stream water Mg / Ca ratio indicates that the signal is subsequently maintained in the streams. RIM gave good predictions of Ca, Mg, and Na flow-weighted concentrations in headwater streams. The difficulty in modelling K and Si suggests a stronger biogeochemical influence on these elements. The observed chemical dilution effect with flow in the streams was related to variation in groundwater levels and element concentration profiles in the riparian zones. This study provides a first step toward specific investigations of the vulnerability of riparian zones to changes induced by forest management or climate change, with focus on BC or other compounds.

  4. Simulation of Snow Processes Beneath a Boreal Scots Pine Canopy

    Institute of Scientific and Technical Information of China (English)

    LI Weiping; LUO Yong; XIA Kun; LIU Xin

    2008-01-01

    A physically-based multi-layer snow model Snow-Atmosphere-Soil-Transfer scheme (SAST) and a land surface model Biosphere-Atmosphere Transfer Scheme (BATS) were employed to investigate how boreal forests influence snow accumulation and ablation under the canopy. Mass balance and energetics of snow beneath a Scots pine canopy in Finland at different stages of the 2003-2004 and 2004-2005 snow seasons are analyzed. For the fairly dense Scots pine forest, drop-off of the canopy-intercepted snow contributes, in some cases, twice as much to the underlying snowpack as the direct throughfall of snow. During early winter snow melting, downward turbulent sensible and condensation heat fluxes play a dominant role together with downward net longwave radiation. In the final stage of snow ablation in middle spring, downward net all-wave radiation dominates the snow melting. Although the downward sensible heat flux is comparable to the net solar radiation during this period, evaporative cooling of the melting snow surface makes the turbulent heat flux weaker than net radiation. Sensitivities of snow processes to leaf area index (LAI) indicate that a denser canopy speeds up early winter snowmelt, but also suppresses melting later in the snow season. Higher LAI increases the interception of snowfall, therefore reduces snow accumulation under the canopy during the snow season; this effect and the enhancement of downward longwave radiation by denser foliage outweighs the increased attenuation of solar radiation, resulting in earlier snow ablation under a denser canopy. The difference in sensitivities to LAI in two snow seasons implies that the impact of canopy density on the underlying snowpack is modulated by interannual variations of climate regimes.

  5. Boreal wildfire emissions from Alaska, USA and Zabaikalsky krai, Russia 2002-2012

    Science.gov (United States)

    Barrett, Kirsten

    2015-04-01

    Boreal forests are the largest terrestrial biome, and account for 27% of global forest cover and a major sink of atmospheric carbon. Increasing wildfire activity in some boreal regions threatens accumulated carbon stocks through combustion, decomposition, and reduced potential for future uptake. There is substantial spatial variability in boreal wildfire characteristics, particularly at the continental scale, which results from differences in climate and vegetation composition between boreal forests in Eurasia and North America. Quantifying boreal wildfire characteristics such as frequency and intensity at a global scale is possible using active fire detection datasets such as those available from AVHRR and MODIS. This study uses the MODIS MCD14ML to compare wildfire emissions (calculated from Fire Radiative Energy) from Interior Alaska, USA and Zabaikalsky krai, Russia between 2002 and 2012. Both regions have experienced increasing fire frequency and severity over the last several decades, likely in response to changing temperature and precipitation regimes. The two regions are similar in size and cumulative emissions, but boreal wildfires in Alaska are generally more intense and produce more emissions per unit area. Wildfire emissions in the Alaskan Interior are also higher due to a longer "residence time" of fires, which may smoulder in the duff layer for several weeks after a front has passed. This "residual burning" accounted for an average of 64% of active fire detections in Interior Alaska, and 47% of those from Zabaikalye, although interannual variability was substantial. The fraction of residual burning was higher in both regions during larger fire years, when presumably more biomass is available to sustain combustion. The relationship between burned area and fraction of residual burning was stronger in Alaska, possibly due to a greater tendency for ground fires to smoulder in thick duff layers found in black spruce-sphagnum dominated areas. Although

  6. Understanding Long-Term Boreal Soil Carbon Accumulation: Insight from a Dynamic Layered Soil Model

    Science.gov (United States)

    Carrasco, J. J.; Harden, J. W.; Neff, J. C.

    2004-12-01

    Despite repeated fire disturbance, low-lying boreal forests have managed to accumulate large and globally significant stocks of C. Furthermore, boreal soils have historically occupied discontinuous and continuous permafrost zones and currently are experiencing a warming climate. Combined, these factors may result in loss of permafrost and increase in decomposition of the soil C. However, before attempting to assess the potential for future change in boreal soil C, the decadal to millennial mechanisms of soil C cycling and accumulation must be well understood. To that end, we developed a dynamic layered long-term soil C model to specifically address: 1) the influence of the soil thermal regime, 2) substrate recalcitrance through humification, and 3) the role of permafrost on the preservation and accumulation of boreal soil C. We included radiocarbon in our model so that we could compare soil C stocks as well as radiocarbon distribution to observations from a well studied Old Black Spruce (OBS) site in Manitoba, Canada. Using parameters from the literature, our results indicate that the accumulation of boreal soil C is dependent on the interaction between the soil thermal regime and humification. While these factors account for much of the soil C accumulation observed at OBS, the weighted average radiocarbon in the modeled deep soil was too new, suggesting a lack of preservation and accumulation of old soil C. However, upon inclusion of a permafrost layer for several centuries, not only the C accumulation and distribution between shallow and deep soil layers improved, but the weighted average radiocarbon markedly improved with respect to the OBS site. Our results suggest that: 1) in the absence of permafrost, deep soil C turnover time is on the order of 200-300 y rather than the previous estimates of up to and greater than 1000 y and 2) the legacy from recent shifts in boreal climate and permafrost must be considered when evaluating current observations.

  7. Implications of floristic and environmental variation for carbon cycle dynamics in boreal forest ecosystems of central Canada

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zicheng; Apps, M.J.; Bhatti, J.S. [Canadan Forest Service, Edmonton (Canada). Northern Forestry Centre

    2002-06-01

    Species composition, detritus, and soil data from 97 boreal forest stands along a transect in central Canada were analysed using Correspondence Analysis to determine the dominant environmental/site variables that differentiate these forest stands. Picea mariana stands were densely clustered together on the understorey DCA plot, suggesting a consistent understorey species composition (feather mosses and Ericaceae), whereas Populus tremuloides stands had the most diverse understorey species composition (ca. 30 species, mostly shrubs and herbs). Pinus banksiana stands had several characteristic species of reindeer lichens (Cladina spp.), but saplings and Pinus seedlings were rare. Although climatic variables showed large variation along the transect, the CCA results indicated that site conditions are more important in determining species composition and differentiating the stand types. Forest floor characteristics (litter and humus layer, woody debris, and drainage) appear to be among the most important site variables. Stands of Picea had significantly higher average carbon (C) densities in the combined litter and humus layer (43,530 kg-C/ha) than either Populus (25,500 kg-C/ha) or Pinus (19,400 kg-C/ha). The thick surface organic layer in lowland Picea stands plays an important role in regulating soil temperature and moisture, and organic-matter decomposition, which in turn affect the ecosystem C-dynamics. During forest succession after a stand-replacing disturbance (e.g. fires), tree biomass and surface organic layer thickness increase in all stand types as forests recover; however, woody biomass detritus first decreases and then increases after ca. 80 yr. Soil C densities show slight decrease with ages in Populus stands, but increase in other stand types. These results indicate the complex C-transfer processes among different components (tree biomass, detritus, forest floor, and soil) of boreal ecosystems at various stages of succession.

  8. Regional-scale surface flux observations across the boreal forest during BOREAS

    DEFF Research Database (Denmark)

    Oncley, S.P.; Lenschow, D.H.; Campos, T.L.;

    1997-01-01

    A major role of the National Center for Atmospheric Research (NCAR) Electra aircraft during the Boreal Ecosystem-Atmosphere Study (BOREAS) was to measure fluxes of momentum, sensible and latent heat, carbon dioxide, and ozone on a transect that crossed the entire boreal forest biome. The observat...... along the transect. Lakes are also found to be large sinks of available radiant energy. Regional ground storage of heat is estimated to be about 30% of the net radiation over the forest, and 40% over the subarctic tundra, largely due to the presence of lakes....

  9. Plants go with the flow : predicting spatial distribution of plant species in the boreal forest

    OpenAIRE

    Zinko, Ursula

    2004-01-01

    The main objectives of this thesis are to study if a topographic wetness index (TWI) could be used as a tool for predicting the spatial distribution of vascular plant species richness in the boreal forest as well as to study congruence in species richness between vascular plants, liverworts, mosses and lichens. A wetness index ln(a/tanβ) based on topography was used to assign a specific TWI-value to every 20 x 20m grid in two 25 km2 boreal forest landscapes (differing in average soil pH) in n...

  10. Effect of Tree Species and Mycorrhizal Colonization on the Archaeal Population of Boreal Forest Rhizospheres▿

    OpenAIRE

    Bomberg, Malin; Timonen, Sari

    2008-01-01

    Group 1.1c Crenarchaeota are the predominating archaeal group in acidic boreal forest soils. In this study, we show that the detection frequency of 1.1c crenarchaeotal 16S rRNA genes in the rhizospheres of the boreal forest trees increased following colonization by the ectomycorrhizal fungus Paxillus involutus. This effect was very clear in the fine roots of Pinus sylvestris, Picea abies, and Betula pendula, the most common forest trees in Finland. The nonmycorrhizal fine roots had a clearly ...

  11. Short-term Response of Breeding Barred Owls to Forestry in a Boreal Mixedwood Forest Landscape

    OpenAIRE

    Ben T. Olsen; Susan J. Hannon; Gordon S. Court

    2006-01-01

    Forestry and other activities are increasing in the boreal mixedwood of Alberta, with a concomitant decrease in older forest. The Barred Owl (Strix varia) is an old-growth indicator species in some jurisdictions in North America. Hence, we radio-tagged Barred Owls in boreal mixedwood in Alberta to determine whether harvesting influenced habitat selection. We used three spatial scales: nest sites, i.e., nest tree and adjacent area of 11.7 m radius around nests, nesting territory of 1000 m radi...

  12. Differentiating moss from higher plants is critical in studying the carbon cycle of the boreal biome

    DEFF Research Database (Denmark)

    Yuan, Wenping; Liu, Shuguang; Dong, Wenjie;

    2014-01-01

    The satellite-derived normalized difference vegetation index (NDVI), which is used for estimating gross primary production (GPP), often includes contributions from both mosses and vascular plants in boreal ecosystems. For the same NDVI, moss can generate only about one-third of the GPP that...... vascular plants can because of its much lower photosynthetic capacity. Here, based on eddy covariance measurements, we show that the difference in photosynthetic capacity between these two plant functional types has never been explicitly included when estimating regional GPP in the boreal region, resulting...

  13. Geoelectrical investigation for the assessment of groundwater conditions: a case study

    Directory of Open Access Journals (Sweden)

    M. Nakhaei

    2005-06-01

    Full Text Available An electrical resistivity survey involving Vertical Electrical Soundings (VES was carried out in the Shooro Basin in Southeast Iran in order to study groundwater conditions such as depth, thickness and aquifer boundaries. Vertical electrical soundings by Schlumberger array were conducted in this area. The resistivity Schlumberger soundings which have a maximum current electrode spacing (AB ranging from 200 m to 600 m were carried out at 207 positions in 19 profiles. Interpretation of these soundings indicates the presence of an alluvial aquifer. This aquifer is divided into eastern and western parts by the Shooro River, which comprises a variable thickness and resistivity of deposits. The average permeability coefficient and resistivity in the western part, especially southwest is higher than the eastern part of the aquifer. Therefore, it seems that Shooro River follows a fault zone in the region. The high resistivity of west part is due to the water quality and the existence of alluvial fan with coarse grain materials. Low aquifer resistivities in the east are associated with finer materials and also brackish water infiltration from the adjacent basin mainly in the central part of the aquifer. Furthermore, zones with high yield potential have been determined in this research based on the resistivity data.

  14. Atmospheric impact of abandoned boreal organic agricultural soils depends on hydrological conditions

    Energy Technology Data Exchange (ETDEWEB)

    Maljanen, M.; Martikainen, P.J. [Univ. of Eastern Finland, Kuopio (Finland). Dept. of Environmental Science], E-Mail: marja.maljanen@uef.fi; Hytonen, J. [Finnish Forest Research Inst., Kannus (Finland); Makiranta, P.; Minkkinen, K. [Helsinki Univ. (Finland). Dept. of Forest Sciences; Laine, J. [Finnish Forest Research Inst., Parkano (Finland)

    2013-09-01

    Drained agricultural peat soils are significant sources of carbon dioxide (CO{sub 2}) but also small sinks for methane (CH{sub 4}). Leaving these soils without any cultivation practice could be an option to mitigate GHG emissions. To test this hypothesis, we measured, over a three year period, net CO{sub 2} exchange and fluxes of CH{sub 4} for five agricultural peat soils that had been abandoned for 20-30 years. Annually, the sites were either small net sinks or sources of CO{sub 2} and CH{sub 4} (-7,8 to 530 g CO{sub 2}-Cm {sup -2} and -0,41 to 1,8 g CH{sub 4}m{sup -2}). Including N{sub 2}O emissions from our previous study, the net (CH{sub 4}+CO{sub 2}+N{sub 2}O) emissions as CO{sub 2} equivalents were lower than in cultivated peat soils and were lowest in the wet year. Therefore, high GHG emissions from these soils could be avoided if the water table is maintained close to the soil surface when photosynthesis is favoured over respiration. (orig.)

  15. Forest Fires Under Abnormal Weather Conditions in Central Siberia

    OpenAIRE

    E. N. Valendik; Ye. K. Kisilyakhov; V. A. Ryzhkova; E. I. Ponomarev; J. G. Goldammer

    2014-01-01

    Occurrence of forest fires and their development to large and catastrophic wildfires are considered for Central Siberia taiga subzones under abnormal drought conditions. The combination of natural conditions that determine the appearance and spread of these fires are given for drought conditions. A map of the large wildfires distribution in the boreal forest subzones of Central Siberia is compiled for 1979 to 2011. A brief analysis is made of dry periods and their relation to the planetary a...

  16. The role of forest floor and trees to the ecosystem scale methane budget of boreal forests

    Science.gov (United States)

    Pihlatie, Mari; Halmeenmäki, Elisa; Peltola, Olli; Haikarainen, Iikka; Heinonsalo, Jussi; Santalahti, Minna; Putkinen, Anuliina; Fritze, Hannu; Urban, Otmar; Machacova, Katerina

    2016-04-01

    Boreal forests are considered as a sink of atmospheric methane (CH4) due to the activity of CH4 oxidizing bacteria (methanotrophs) in the soil. This soil CH4 sink is especially strong for upland forest soils, whereas forests growing on organic soils may act as small sources due to the domination of CH4 production by methanogens in the anaerobic parts of the soil. The role of trees to the ecosystem-scale CH4 fluxes has until recently been neglected due to the perception that trees do not contribute to the CH4 exchange, and also due to difficulties in measuring the CH4 exchange from trees. Findings of aerobic CH4 formation in plants and emissions from tree-stems in temperate and tropical forests during the past decade demonstrate that our understanding of CH4 cycling in forest ecosystems is not complete. Especially the role of forest canopies still remain unresolved, and very little is known of CH4 fluxes from trees in boreal region. We measured the CH4 exchange of tree-stems and tree-canopies from pine (Pinus sylvestris), spruce (Picea abies) and birch (Betula pubescens, Betula pendula) trees growing in Southern Finland (SMEAR II station) on varying soil conditions, from upland mineral soils to paludified soil. We compared the CH4 fluxes from trees to forest-floor CH4 exchange, both measured by static chambers, and to CH4 fluxes measured above the forest canopy by a flux gradient technique. We link the CH4 fluxes from trees and forest floor to physiological activity of the trees, such as transpiration, sap-flow, CO2 net ecosystem exchange (NEE), soil properties such as temperature and moisture, and to the presence of CH4 producing methanogens and CH4 oxidizing methanotrophs in trees or soil. The above canopy CH4 flux measurements show that the whole forest ecosystem was a small source of CH4 over extended periods in the spring and summer 2012, 2014 and 2015. Throughout the 2013-2014 measurements, the forest floor was in total a net sink of CH4, with variation

  17. Reconstruction of Holocene carbon dynamics in a large boreal peatland complex, southern Finland

    Science.gov (United States)

    Mathijssen, Paul J. H.; Väliranta, Minna; Korrensalo, Aino; Alekseychik, Pavel; Vesala, Timo; Rinne, Janne; Tuittila, Eeva-Stiina

    2016-06-01

    Holocene peatland development and associated carbon (C) dynamics were reconstructed for a southern boreal Finnish peatland complex with fen and bog areas. In order to assess the role of local factors and long-term allogenic climate forcing in peatland development patterns, we studied a total of 18 peat cores and reconstructed vertical peat growth and lateral peat area expansion rates, the C accumulation rate (CAR), past vegetation composition and past methane (CH4) fluxes. We combined fossil plant data with measured contemporary CH4 flux - vegetation relationship data to reconstruct CH4 fluxes over time. When these reconstructions were added to the CAR estimations, a more complete picture of Holocene-scale C dynamics was achieved. Basal peat ages showed that expansion of the peat area was rapid between 11,000 and 8000 cal. BP, but decreased during the dry mid-Holocene and is probably currently limited by basal topography. A similar pattern was observed for peat growth and CAR in the fen core, whereas in the bog core CAR increased after ombrotrophication, i.e. after 4400 cal. BP. The effect of fire on vegetation and CAR was more conspicuous at the bog site than at the fen site. The CH4 flux reconstructions showed that during the Holocene CH4 emissions at the fen site decreased from 19 ± 15 to 16 ± 8 g CH4 m-2 yr-1 and at the bog site from 20 ± 15 to 14 ± 8 g CH4 m-2 yr-1. Our results suggest that a combination of changing climate, fire events and local conditions have modified the autogenic peatland development and C dynamics.

  18. Long-Term Satellite Detection of Post-Fire Vegetation Trends in Boreal Forests of China

    Directory of Open Access Journals (Sweden)

    Kunpeng Yi

    2013-12-01

    Full Text Available This paper describes the long-term effects on vegetation following the catastrophic fire in 1987 on the northern Great Xing’an Mountain by analyzing the AVHRR GIMMS 15-day composite normalized difference vegetation index (NDVI dataset. Both temporal and spatial characteristics were analyzed for natural regeneration and tree planting scenarios from 1984 to 2006. Regressing post-fire NDVI values on the pre-fire values helped identify the NDVI for burnt pixels in vegetation stands. Stand differences in fire damage were classified into five levels: Very High (VH, High (H, Moderate (M, Low (L and Slight (S. Furthermore, intra-annual and inter-annual post-fire vegetation recovery trajectories were analyzed by deriving a time series of NDVI and relative regrowth index (RRI values for the entire burned area. Finally, spatial pattern and trend analyses were conducted using the pixel-based post-fire annual stands regrowth index (SRI with a nonparametric Mann-Kendall (MK statistics method. The results show that October was a better period compared to other months for distinguishing the post- and pre-fire vegetation conditions using the NDVI signals in boreal forests of China because colored leaves on grasses and shrubs fall down, while the leaves on healthy trees remain green in October. The MK statistics method is robustly capable of detecting vegetation trends in a relatively long time series. Because tree planting primarily occurred in the severely burned area (approximately equal to the Medium, High and Very High fire damage areas following the Daxing’anling fire in 1987, the severely burned area exhibited a better recovery trend than the lightly burned regions. Reasonable tree planting can substantially quicken the recovery and shorten the restoration time of the target species. More detailed satellite analyses and field data will be required in the future for a more convincing validation of the results.

  19. Measurement and modeling of bryophyte evaporation in a boreal forest chronosequence

    Energy Technology Data Exchange (ETDEWEB)

    Bond-Lamberty, Benjamin; Gower, Stith T.; Amiro, Brian; Ewers, Brent

    2011-01-19

    The effects of changing climate and disturbance on forest water cycling are not well understood. In particular bryophytes contribute significantly to forest evapotranspiration (ET) in poorly-drained boreal forests, but few studies have directly measured this flux and how it changes with stand age and soil drainage. We used large chambers to measure bryophyte evaporation (E) in Canadian Picea mariana forests of varying ages and soil drainages, as well under controlled laboratory conditions, and modeled daily E using site-specific meteorological data to drive a Penman-Monteith-based model. Field measurements of E averaged 0.37 mm day-1, and ranged from 0.03 (Pleurozium schreberii in a 77-year-old dry stand) to 1.43 mm day-1 (Sphagnum riparium in a 43-year-old bog). canopy resistance ranged from ~0 (at 25 °C, some values were <0) to ~1500 s m-1 for dry, cold (5 °C) mosses. In the laboratory, moss canopy resistance was constant until a moss water content of ~6 g g-1 and then climbed sharply with further drying; no difference was observed between the three moss groups (feather mosses, hollow mosses, and hummock mosses) tested. Modeled annual E fluxes from bryophytes ranged from 0.4 mm day-1, in the well-drained stands, to ~1 mm day-1 in the 43-year-old bog, during the growing season. Eddy covariance data imply that bryophytes contributed 18-31% and 49-69% to the total ET flux, at the well- and poorly-drained stands respectively. Bryophyte E was greater in bogs than in upland stands, was driven by low-lying mosses, and did not vary with stand age; this suggests that shifts in forest age due to increasing fire will have little effect on the bryophyte contribution to ET.

  20. Reconstruction of Holocene carbon dynamics in a large boreal peatland complex, southern Finland

    Science.gov (United States)

    Mathijssen, Paul J. H.; Väliranta, Minna; Korrensalo, Aino; Alekseychik, Pavel; Vesala, Timo; Rinne, Janne; Tuittila, Eeva-Stiina

    2016-06-01

    Holocene peatland development and associated carbon (C) dynamics were reconstructed for a southern boreal Finnish peatland complex with fen and bog areas. In order to assess the role of local factors and long-term allogenic climate forcing in peatland development patterns, we studied a total of 18 peat cores and reconstructed vertical peat growth and lateral peat area expansion rates, the C accumulation rate (CAR), past vegetation composition and past methane (CH4) fluxes. We combined fossil plant data with measured contemporary CH4 flux - vegetation relationship data to reconstruct CH4 fluxes over time. When these reconstructions were added to the CAR estimations, a more complete picture of Holocene-scale C dynamics was achieved. Basal peat ages showed that expansion of the peat area was rapid between 11,000 and 8000 cal. BP, but decreased during the dry mid-Holocene and is probably currently limited by basal topography. A similar pattern was observed for peat growth and CAR in the fen core, whereas in the bog core CAR increased after ombrotrophication, i.e. after 4400 cal. BP. The effect of fire on vegetation and CAR was more conspicuous at the bog site than at the fen site. The CH4 flux reconstructions showed that during the Holocene CH4 emissions at the fen site decreased from 19 ± 15 to 16 ± 8 g CH4 m-2 yr-1 and at the bog site from 20 ± 15 to 14 ± 8 g CH4 m-2 yr-1. Our results suggest that a combination of changing climate, fire events and local conditions have modified the autogenic peatland development and C dynamics.

  1. Regional Heat Sources and the Active and Break Phases of Boreal Summer Intraseasonal Variability

    Energy Technology Data Exchange (ETDEWEB)

    Annamalai, H; Sperber, K R

    2003-12-15

    The boreal summer intraseasonal variability (BSISV) associated with the 30-50 day mode is represented by the co-existence of three components, poleward propagation of convection over the Indian and tropical west Pacific longitudes and eastward propagation along the equator. The hypothesis that the three components influence each other has been investigated using observed OLR, NCEP-NCAR reanalysis, and solutions from an idealized linear model. The null hypothesis is that the three components are mutually independent. Cyclostationary EOF (CsEOF) analysis is applied on filtered OLR to extract the life-cycle of the BSISV. The dominant mode of CsEOF is significantly tied to observed rainfall over the Indian subcontinent. The components of the heating patterns from CsEOF analysis serve as prescribed forcings for the linear model. This allows us to ascertain which heat sources and sinks are instrumental in driving the large-scale monsoon circulation during the BSISV life-cycle. We identify three new findings: (1) the circulation anomalies that develop as a Rossby wave response to suppressed convection over the equatorial Indian Ocean associated with the previous break phase of the BSISV precondition the ocean-atmosphere system in the western Indian Ocean and trigger the next active phase of the BSISV, (2) the development of convection over the tropical west Pacific forces descent anomalies to the west. This, in conjunction with the weakened cross-equatorial flow due to suppressed convective anomalies over the equatorial Indian Ocean reduce the tropospheric moisture over the Arabian Sea, and promote westerly wind anomalies that do not recurve over India. As a result the low-level cyclonic vorticity shifts from India to southeast Asia and break conditions are initiated over India, and (3) the circulation anomalies forced by equatorial Indian Ocean convective anomalies significantly influence the active/break phases over the tropical west Pacific. Our model solutions support

  2. The reasons for conceptual contradictions in evaluating hydrological role of boreal forests

    Directory of Open Access Journals (Sweden)

    A. A. Onuchin

    2015-04-01

    Full Text Available The paper attempts to resolve contradictions in the evaluation of the hydrological significance of the boreal forest. The article focuses on the study of the hydrological cycle mainly at the local level in connection with the specificity of vegetation and background of climate. It is stated that the ratio between evaporation and runoff in the warm season is mainly determined by the productivity of land, and less by the type of vegetation, whether forests or other types of land. This effect is due to the fact that the root systems of large trees act as «powerful submersible pumps», evaporating moisture including from the lower soil horizons. In the cold season, when precipitation falls as snow and is permanently preserved in the snow cover, the intensity and direction of the flow of water is not associated with the productivity of vegetation, and is mainly determined by the type of vegetation (forest, treeless space and by environmental conditions. It is argued that the ambiguity of the impact of forests on the redistribution of precipitation between evaporation and runoff is due mainly features balance of the snow moisture, which is defined as the structure of the forest cover as well as the environment. Concepts of the geographically-determined hydrological role of forests are suggested. The results explain the contradictions in the hydrological role of forests (water consumption and water yield and may be useful in the formation of land-use strategies in the regions where relationship problems of water resources and forest cover are relevant.

  3. Understanding COS Fluxes in a Boreal Forest: Towards COS-Based GPP Estimates.

    Science.gov (United States)

    Chen, H.; Kooijmans, L.; Franchin, A.; Keskinen, H.; Levula, J.; Mammarella, I.; Maseyk, K. S.; Pihlatie, M.; Praplan, A. P.; Seibt, U.; Sun, W.; Vesala, T.

    2015-12-01

    Carbonyl Sulfide (COS) is a promising new tracer that can be used to partition the Net Ecosystem Exchange into gross primary production (GPP) and respiration. COS and CO2 vegetation fluxes are closely related as these gases share the same diffusion pathway into stomata, which makes COS a potentially powerful tracer for GPP. While vegetative uptake is the largest sink of COS, the environmental drivers are poorly understood, and soil fluxes represent an important but relatively unconstrained component. Therefore, the realization of the COS tracer method requires proper characterization of both soil and ecosystem fluxes. A campaign to provide better constrained soil and ecosystem COS flux data for boreal forests took place in the summer of 2015 at the SMEAR II site in Hyytiälä, Finland. Eddy covariance flux measurements were made above the forest canopy on an Aerodyne continuous-wave quantum cascade laser (QCL) system that is capable of measuring COS, CO2, CO and H2O. Soil COS fluxes were obtained using modified LI-COR LI-8100 chambers together with high accuracy concentration measurements from another Aerodyne QCL instrument. The same instrument alternately measured concentrations in and above the canopy on a cycle through 4 heights, which will be used to calculate ecosystem fluxes using the Radon-tracer method, providing ecosystem fluxes under low-turbulent conditions. We will compare ecosystem fluxes from both eddy covariance and profile measurements and show estimates of the fraction of ecosystem fluxes attributed to the soil component. With the better understanding of ecosystem and soil COS fluxes, as obtained with this dataset, we will be able to derive COS-based GPP estimates for the Hyytiälä site.

  4. Modelling Regional Surface Energy Exchange and Boundary Layer Development in Boreal Sweden — Comparison of Mesoscale Model (RAMS Simulations with Aircraft and Tower Observations

    Directory of Open Access Journals (Sweden)

    Meelis Mölder

    2012-10-01

    Full Text Available Simulation of atmospheric and surface processes with an atmospheric model (RAMS during a period of ten days in August 2001 over a boreal area in Sweden were compared to tower measurements and aircraft measurements of vertical profiles as well as surface fluxes from low altitude flights. The shape of the vertical profiles was simulated reasonably well by the model although there were significant biases in absolute values. Surface fluxes were less well simulated and the model showed considerable sensitivity to initial soil moisture conditions. The simulations were performed using two different land cover databases, the original one supplied with the RAMS model and the more detailed CORINE database. The two different land cover data bases resulted in relatively large fine scale differences in the simulated values. The conclusion of this study is that RAMS has the potential to be used as a tool to estimate boundary layer conditions and surface fluxes and meteorology over a boreal area but also that further improvement is needed.

  5. Effect of water level drawdown on decomposition in boreal peatlands

    Science.gov (United States)

    Straková, Petra; Penttilä, Timo; Laiho, Raija

    2010-05-01

    Plant litter production and decomposition are key processes in element cycling in most ecosystems. In peatlands, there has been a long-term imbalance between litter production and decay caused by high water levels (WL) and consequent anoxia. This has resulted in peatlands being a significant sink of carbon (C) from the atmosphere. However, peatlands are experiencing both "natural" (global climate change) and anthropogenic (ditching) changes that threaten their ability to retain this ecosystem identity and function. Many of these alterations can be traced back to WL drawdown, which can cause increased aeration, higher acidity, falling temperatures, and a greater probability of drought. Such changes are also associated with an increasing decomposition rate, and therefore a greater amount of C released back to the atmosphere. Yet studies about how the overall C balance of peatlands will be affected have come up with conflicting conclusions, demonstrating that the C store could increase, decrease, or remain static. A factor that has been largely overlooked is the change in litter type composition following persistent WL drawdown. It is the aim of our study, then, to help to resolve this issue. We studied the effects of short-term (ca. 4 years) and long-term (ca. 40 years) persistent WL drawdown on the decomposition of numerous types of above-ground and below-ground plant litters at three boreal peatland sites: bog, oligotrophic fen and mesotrophic fen. We thus believe that enough permutations have been created to obtain a good assessment of how each factor, site nutrient level, WL regime, and litter type composition, influences decomposition. We used the litter bag method to measure the decomposition rates: placed measured amounts of plant litter, or cellulose strips as a control, into closed mesh bags, and installed the bags in the natural environment for decomposition for each litter type for varying amounts of time. Following litter bag recovery, the litter was

  6. Carbon dioxide and water vapour exchange from understory species in boreal forest.

    NARCIS (Netherlands)

    Heijmans, M.M.P.D.; Arp, W.J.; Chapin, F.S.

    2004-01-01

    Although recent eddy covariance measurements in boreal forests provide CO2 and energy exchange data for the whole ecosystem, very little is known about the role of the understory vegetation. We conducted chamber flux measurements in an Alaskan black spruce forest in order to compare CO2 and water va

  7. Emaciation and larval filarioid nematode infection in boreal owls (Aegolius funereus).

    Science.gov (United States)

    Larrat, Sylvain; Dallaire, André D; Lair, Stéphane

    2012-01-01

    Microfilariae are considered non-pathogenic in wild birds. The objective of the current communication is to report host reactions to microfilarial infection of unusual intensity in emaciated boreal owls (Aegolius funereus). An unusually large number of boreal owls (n = 21) were submitted to the Canadian Cooperative Wildlife Health Center-Quebec Region for post-mortem examination during the winter of 2009. Nineteen out of 21 birds were considered emaciated based on atrophy of adipose tissue and pectoral muscles and suboptimal weight. A microscopic examination of a subset of nine owls revealed the presence of microfilariae in six owls. Three of the birds with a heavy parasite burden had masses of larval nematodes obstructing large vessels of the lungs. The emaciated owls are believed to have died from starvation due to a cyclic decrease in prey abundance in the boreal forest. This cycle also drives winter movements of boreal owls to urbanized areas of southern Quebec, presumably accounting for the large number of birds submitted in 2009. In the most severely infected owls, the extreme microfilarial burden might have caused an alteration in circulatory dynamics, gaseous exchanges and also probably some metabolic cost. Consequently, microfilariae could have significantly contributed to the death of some of these owls. PMID:22834547

  8. Evidence for shift from acidobacteria to proteobacteria dominance in soil profile of boreal acid sulphate soils

    Czech Academy of Sciences Publication Activity Database

    Chroňáková, Alica; Bryndová, Michala; Otáhalová, Šárka; Yli-Halla, M.; Šimek, Miloslav

    Dijon : INRA, 2014. s. 276. [Global Soil Biodiversity Conference. Assessing soil biodiversity and its role for ecosystem services /1./. 02.12.2014-05.12.2014, Dijon] Institutional support: RVO:60077344 Keywords : boreal acid sulphate soils * soil profile * bacteria community structure * subsoil horizons Subject RIV: EH - Ecology, Behaviour

  9. Optimal conservation resource allocation under variable economic and ecological time discounting rates in boreal forest

    DEFF Research Database (Denmark)

    Mazziotta, Adriano; Montesino Pouzols, Federico; Mönkkönen, Mikko;

    2016-01-01

    Resource allocation to multiple alternative conservation actions is a complex task. A common trade-off occurs between protection of smaller, expensive, high-quality areas versus larger, cheaper, partially degraded areas. We investigate optimal allocation into three actions in boreal forest: current...

  10. Radiocarbon dating of fluvial organic matter reveals land-use impacts in boreal peatlands

    DEFF Research Database (Denmark)

    Hulatt, Chris J.; Kaartokallio, Hermanni; Oinonen, Markku;

    2014-01-01

    This study measured the effects of land use on organic matter released to surface waters in a boreal peat catchment using radiocarbon dating of particulate and dissolved organic carbon (POC and DOC), DOC concentration, stable carbon and nitrogen isotope composition, and optical measurements...

  11. Boreal Forests in Permafrost Landscapes: Changing Structure and Function in Response to Climate Warming

    Science.gov (United States)

    Baltzer, J. L.; Quinton, W. L.; Sonnentag, O.

    2014-12-01

    Boreal forests occupy latitudes that are experiencing the greatest rates of warming on earth, a pattern that is expected to continue over the coming decades. Much of the Boreal is underlain by permafrost, which can be expected to have important consequences for forest structure, composition and functioning as the climate warms. The southern margin of permafrost is especially susceptible to warming, since in this region, the permafrost is discontinuous, relatively thin, warm and ice-rich. In the discontinuous permafrost zone, permafrost often forms the physical foundation on which trees develop, forming tree-covered peat plateaus where trees contribute to permafrost maintenance and aggradation processes through reductions in radiation load and changes in snow accumulation. Forests are restricted to peat plateaus while wetland communities occupy intervening permafrost-free areas. The extent and distribution of each land cover type is an important determinant of how boreal forest-wetland landscapes in the discontinuous permafrost zone function as part of the climate system. Climate warming is rapidly thawing permafrost leading to ground surface subsidence and transformation of the forests into wetlands, increasing both the areal extent and connectivity of the latter. In this presentation, we will use an integrative framework at the ForestGEO Scotty Creek Forest Dynamics Plot site near Fort Simpson, Northwest Territories, Canada to demonstrate the changes in ecological, hydrological and biosphere-atmosphere interactions within this boreal forest-wetland landscape characterized by rapidly degrading permafrost.

  12. A framework for modelling the annual cycle of trees in boreal and temperate regions

    NARCIS (Netherlands)

    Hänninen, H.; Kramer, K.

    2007-01-01

    Models of the annual development cycle of trees in boreal and temperate regions were reviewed and classified on the basis of their ecophysiological assumptions. In our classification we discern two main categories of tree development: 1) fixed sequence development, which refers to irreversible ontog

  13. Negligible in-stream processing of dissolved organic matter in low order boreal streams

    Science.gov (United States)

    Kothawala, Dolly; Ji, Xing; Laudon, Hjalmar; Ågren, Anneli; Futter, Martyn; Köhler, Stephan; Tranvik, Lars

    2016-04-01

    Low order boreal streams have been considered to be reactive interfaces where dissolved organic matter (DOM) enters inland waters from the surrounding catchment soils. Disentangling the relative influence of key environmental factors suspected to influence stream water DOM composition is highly relevant for predicting the reactivity, and fate of terrestrial DOM. Here, we examined changes to DOM composition using optical approaches from 17 boreal streams, ranging from first to fourth order, over 14 months. We identified two specific fluorescing components, which expressed either a clear mire-wetland or forest signature, providing distinct molecular markers of land cover that is typical of the boreal ecozone. In fact, land cover alone explained 49% of the variability in stream DOM composition. In contrast, seasonal fluctuations in hydrology only contributed to minor shifts (8%) in DOM composition. Perhaps most intriguingly, in-stream transformations to DOM composition were undetectable, suggesting that the extent of in-stream processing was negligible. These findings suggest that low order boreal streams act as passive pipes rather than active reactors. Ultimately, we find that that in-stream processing of DOM was restricted by water residence times (less than 2 days). In summary, these results now leave us better equipped to predict where in the landscape, and when during the year, key DOM transformations may occur within the aquatic conduit.

  14. An age-calibrated record of upper Campanian – Maastrichtian climate change in the Boreal Realm

    DEFF Research Database (Denmark)

    Thibault, Nicolas Rudolph; Schovsbo, Niels; Harlou, Rikke;

    temperatures (SSTs) in the Boreal Realm. Three warming events punctuate the overall cooling trend of the latest Cretaceous: (1) the late Campanian climatic optimum (73.9–71.6 Ma) is characterized by maximum SSTs of 20°C, (2) the mid-Maastrichtian warming (69.7–68 Ma) is characterized by stable SSTs around 17°C...

  15. Modelling Holocene carbon accumulation and methane emissions of boreal wetlands – an Earth system model approach

    Directory of Open Access Journals (Sweden)

    R. J. Schuldt

    2013-03-01

    Full Text Available Since the Last Glacial Maximum, boreal wetlands have accumulated substantial amounts of peat, estimated at 180–621 Pg of carbon. Wetlands have significantly affected the atmospheric greenhouse gas composition in the past and will play a significant role in future changes of atmospheric CO2 and CH4 concentrations. In order to investigate those changes with an Earth system model, biogeochemical processes in boreal wetlands need to be accounted for. Thus, a model of peat accumulation and decay was developed and included in the land surface model JSBACH of the Max Planck Institute Earth System Model (MPI-ESM. Here we present the evaluation of model results from 6000 yr BP to the pre-industrial period. Over this period of time, 240 Pg of peat carbon accumulated in the model in the areas north of 40° N. Simulated peat accumulation rates agree well with those reported for boreal wetlands. The model simulates CH4 emissions of 49.3 Tg CH4 yr−1 for 6000 yr BP and 51.5 Tg CH4 yr−1 for pre-industrial times. This is within the range of estimates in the literature, which range from 32 to 112 Tg CH4 yr−1 for boreal wetlands. The modelled methane emission for the West Siberian Lowlands and Hudson Bay Lowlands agree well with observations. The rising trend of methane emissions over the last 6000 yr is in agreement with measurements of Antarctic and Greenland ice cores.

  16. Strengthening of the boreal winter Hadley circulation and its connection with ENSO

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Empirical orthogonal function (EOF) analysis is carried out for the year-to-year variability of the boreal winter (DJF)mass stream function of the mean meridional circulation (MMC) during the period 1948-2005. The results demonstrate that it is dominated by the equatorially asymmetric and symmetric modes. Further analysis shows that the former mode is linked with the boreal winter Hadley cell mainly on the decadal time-scale, and the latter on the interannual time-scale. The asymmetric mode index (AMI) with a clear upward trend contributes to the decadal strengthening of the boreal Hadley circulation, and is closely correlated with the tropical SST warming, especially in the region of Indo-west Pacific warm pool (INWP). Furthermore, the AMI also contributes to the abrupt change of the correlation coefficient between the boreal Hadley circulation and ENSO after 1976. The symmetric mode index (SMI) with robust and stable linkage with ENSO shows a significant interannual variability, suggesting that the variability of the Hadley circulation is mainly associated with ENSO on the interannual time-scale.

  17. Hydrogeochemical conditions at the Haestholmen site

    International Nuclear Information System (INIS)

    The characterisation and interpretation of groundwater geochemistry has been ongoing at several study sites for spent fuel disposal in Finland since the late 1980s. The former evaluation of the Haestholmen groundwater from depths to 240 m was performed between 1980 and 1992 during the investigations for the construction of the reactor waste repository. Haestholmen was included in the site characterisation programme for spent fuel disposal in 1997. The sampling of groundwater down to 1000 m was started in 1997 from deep boreholes and this study presents the evaluation of the hydro-geochemistry at Haestholmen extending below 200m. The dilute HCO3-rich groundwater seems to be limited to the upper 60 m and it is probably controlled by subhorizontal zone R1. According to the tritium data, the dilute groundwater is recently infiltrated, less than 45 years ago. Brackish SO4-rich groundwater has been obtained from a depth of about 60 m to a depth of about 600 m. The data show a strong input of the Litorina sea water mixed in the groundwater system as well as input of glacial melt water in the brackish ground-water layer. The infiltration of Litorina sea water is based on marine Br/Cl ratios, δO-18/δH-2, and δS-34 data. The C-14 datings, together with a higher salinity than the present Baltic indicate a Litorina Sea water origin. Melt water is interpreted according to decreasing δH-2 and δO-18 with salinity and depth in the brackish water layer. The saline groundwater is obtained from below 600 m. Stable isotope (δO-18 and δH-2) results, high Ca/Cl, Ca/Mg and Br/Cl ratios suggest a hydrothermal saline end-member. However, the marine signature is also observable in saline water, which is interpreted to originate from the Pre-Weichselian Sea, possibly from the Eem Sea. In accordance with another study site, Olkiluoto, the hydrochemistry of Haestholmen seems to contain a layered sequence of climatic and shoreline changes from modern times through former Baltic stages in

  18. Hydrogeochemical conditions at the Haestholmen site

    Energy Technology Data Exchange (ETDEWEB)

    Luukkonen, A.; Pitkaenen, P. [VTT Communities and Infrastructure, Espoo (Finland); Ruotsalainen, P. [Fintact Oy (Finland); Leino-Forsman, H. [VTT Chemical Technology, Espoo (Finland); Snellman, M. [Posiva Oy, Helsinki (Finland)

    1999-06-01

    The characterisation and interpretation of groundwater geochemistry has been ongoing at several study sites for spent fuel disposal in Finland since the late 1980s. The former evaluation of the Haestholmen groundwater from depths to 240 m was performed between 1980 and 1992 during the investigations for the construction of the reactor waste repository. Haestholmen was included in the site characterisation programme for spent fuel disposal in 1997. The sampling of groundwater down to 1000 m was started in 1997 from deep boreholes and this study presents the evaluation of the hydro-geochemistry at Haestholmen extending below 200m. The dilute HCO{sub 3}-rich groundwater seems to be limited to the upper 60 m and it is probably controlled by subhorizontal zone R1. According to the tritium data, the dilute groundwater is recently infiltrated, less than 45 years ago. Brackish SO{sub 4}-rich groundwater has been obtained from a depth of about 60 m to a depth of about 600 m. The data show a strong input of the Litorina sea water mixed in the groundwater system as well as input of glacial melt water in the brackish ground-water layer. The infiltration of Litorina sea water is based on marine Br/Cl ratios, {delta}O-18/{delta}H-2, and {delta}S-34 data. The C-14 datings, together with a higher salinity than the present Baltic indicate a Litorina Sea water origin. Melt water is interpreted according to decreasing {delta}H-2 and {delta}O-18 with salinity and depth in the brackish water layer. The saline groundwater is obtained from below 600 m. Stable isotope ({delta}O-18 and {delta}H-2) results, high Ca/Cl, Ca/Mg and Br/Cl ratios suggest a hydrothermal saline end-member. However, the marine signature is also observable in saline water, which is interpreted to originate from the Pre-Weichselian Sea, possibly from the Eem Sea. In accordance with another study site, Olkiluoto, the hydrochemistry of Haestholmen seems to contain a layered sequence of climatic and shoreline changes

  19. Contribution of Soil Surface CO2 Efflux to Boreal Forest Net Ecosystem Flux: Measurements and Modeling

    Science.gov (United States)

    Niinisto, S. M.; Kellomaki, S.

    2001-05-01

    The aims of the study are to assess the contribution of measured soil surface CO2 efflux to boreal forest net ecosystem flux and to test whether modeled component fluxes such as leaf and surface soil fluxes are consistent with the net flux measured from a tower over a forest stand. Net ecosystem flux was measured continuously in a boreal Scots pine forest in eastern Finland (62° 52'N, 30° 49'E) during the growing period in 2000. Height and diameter of trees in this 50-year-old stand ranged from 10 to 13 m and from 9 to 12 cm, respectively, for 80 % of trees. Eddy-flux measurements were made at the top of a 32-m tower, about 20 m above the canopy. Wind velocity and virtual temperature were measured with a three-axis sonic anemometer. CO2 fluctuations at 32 m were continuously monitored with a CO2 analyzer. Raw data were sampled at 10 Hz and 1/2 hr fluxes calculated. Soil surface CO2 efflux was measured on the top of a feather moss or lichen cover with an IRGA and four automated open dynamic chambers, each equipped with a PAR sensor and air temperature probe. Chambers of 19 cm diameter were made of transparent PMMA. Measurements were made twice per hr, lasting 1 min each. Periods considered in this study included both early and late season conditions, since data from the automated soil surface efflux measurements were available from May to June as well as from August to September. In this study, we aim to compare the measured soil surface CO2 efflux with simultaneously measured net ecosystem flux. The performance of the automated chambers will be tested by comparing with simultaneous measurements from a dark closed static chamber at the same site. A simple regression model, using soil surface temperature as an independent variable, will be built using the static dark chamber data from the previous years. A rough correction for the carbon uptake of moss will be made. This model could be validated later with automated measurements. To investigate further the

  20. Using dissolved organic matter (DOM) composition to detect permafrost thaw in arctic and boreal watersheds

    Science.gov (United States)

    ODonnell, J. A.; Aiken, G.; Walvoord, M. A.; Butler, K.

    2013-12-01

    Permafrost thaw can profoundly alter hydrology and carbon dynamics in northern high-latitude regions. Thawing of permafrost has been detected through monitoring of borehole temperatures and active layer thickness (ALT), but these measurements have limited spatial inference and primarily reflect local conditions. Remote sensing analyses have been useful for detecting thermokarst features, yet have limited application in upland forests or in ice-poor regions not susceptible to ground subsidence. Analysis of stream discharge time-series (e.g. recession flow analysis) can be a powerful tool for detecting watershed-scale changes in ALT, but long-term hydrologic data is sparse in many northern regions. Given the large pool of organic carbon (C) in permafrost soils, most research has focused on how permafrost thaw impacts C released to the atmosphere. However, permafrost thaw may also modify the lateral flux of C from terrestrial to aquatic systems, often through increasing groundwater discharge to stream flow. Here, we present data from arctic (n=36) and boreal rivers (n=60) of Alaska to address the question: can DOM character in rivers be used as a tool for detecting permafrost thaw in high-latitude watersheds? We hypothesize that the chemical composition of DOM is sensitive to permafrost configuration as a control on (1) groundwater transit times, (2) microbial processing, and (3) stabilization in mineral soils. Using measurements of DOM optical properties, chemical fractionation, and 14C-DOC, we distinguished DOM character between supra- and sub-permafrost aquifers. DOM transported from supra-permafrost soils to rivers is subject to seasonal thawing and re-freezing of the active layer. DOC concentrations peaked during spring snowmelt (7.5 to 41.7 mgC L-1), when frozen soils confine subsurface flow to organic-soil horizons, and declined during summer (2.6 to 27.3 mgC L-1), when soils of the active layer thaw. Δ14C-DOC in three boreal rivers also declined seasonally

  1. The role of lakes in carbon cycling in boreal catchments

    Energy Technology Data Exchange (ETDEWEB)

    Rantakari, M.

    2010-07-01

    Lakes are an important component of ecosystem carbon cycle through both organic carbon sequestration and carbon dioxide and methane emissions, although they cover only a small fraction of the Earth's surface area. Lake sediments are considered to be one of rather permanent sinks of carbon in boreal regions and furthermore, freshwater ecosystems process large amounts of carbon originating from terrestrial sources. These carbon fluxes are highly uncertain especially in the changing climate. The present study provides a large-scale view on carbon sources and fluxes in boreal lakes situated in different landscapes. We present carbon concentrations in water, pools in lake sediments, and carbon gas (CO{sub 2} and CH{sub 4}) fluxes from lakes. The study is based on spatially extensive and randomly selected Nordic Lake Survey (NLS) database with 874 lakes. The large database allows the identification of the various factors (lake size, climate, and catchment land use) determining lake water carbon concentrations, pools and gas fluxes in different types of lakes along a latitudinal gradient from 60 deg N to 69 deg N. Lakes in different landscapes vary in their carbon quantity and quality. Carbon (C) content (total organic and inorganic carbon) in lakes is highest in agriculture and peatland dominated areas. In peatland rich areas organic carbon dominated in lakes but in agricultural areas both organic and inorganic C concentrations were high. Total inorganic carbon in the lake water was strongly dependent on the bedrock and soil quality in the catchment, especially in areas where human influence in the catchment is low. In inhabited areas both agriculture and habitation in the catchment increase lake TIC concentrations, since in the disturbed soils both weathering and leaching are presumably more efficient than in pristine areas. TOC concentrations in lakes were related to either catchment sources, mainly peatlands, or to retention in the upper watercourses. Retention

  2. Land management strategies for the long-term persistence of boreal woodland caribou in central Saskatchewan

    Directory of Open Access Journals (Sweden)

    A. Alan Arsenault

    2011-09-01

    Full Text Available We investigated landscape changes and their potential effects on woodland caribou-boreal ecotype (Rangifer tarandus caribou within a portion of the Smoothstone-Wapaweka Woodland Caribou Management Unit (SW-WCMU. The SW-WCMU is one of eight areas delineated by the Province of Saskatchewan for potential recovery planning efforts for boreal caribou, and is one of four management units located on the Boreal Plain Ecozone. The Prince Albert Greater Ecosystem (PAGE study area was selected within the SW-WCMU for intensive study from 2004 - 2008. Studies focused on quantifying a suite of landscape and population parameters. This paper presents a summary of study results to date and recommends land management strategies intended to contribute to the long-term viability of boreal caribou in the central boreal plain ecoregion of Saskatchewan. The PAGE study area has undergone structural changes from an area that historically presented a lesser amount but well connected mature coniferous forest, to a currently larger amount of mature coniferous stands fragmented by a highly developed network of roads and trails. Movement data pointed to highly clustered use of the landscape by small groups of caribou and smaller home ranges when compared to 15 years ago. Calving sites were located within each individual home range in treed peatland and distant from hardwood/mixedwood forest stands, roads and trails access. Adult annual survival rates were low, averaging 73% over the course of the study. In order to ensure a self-sustaining population level, study results clearly point to the need for landscape restoration to reduce the level of anthropogenic disturbances in some key parts of the study area. Key strategies include retention of mature softwood forest interior proximate to local areas of caribou activity, protection of calving habitat, improving structural connectivity, planning disturbances (forest harvesting, fire salvage, resource exploration, access

  3. Canopy interaction with precipitation and sulphur deposition in two boreal forests of Quebec, Canada

    International Nuclear Information System (INIS)

    The interaction of atmospheric sulphur (S) was investigated within the canopies of two boreal forests in Québec, Canada. The net canopy exchange approach, i.e. the difference between S–SO4 in throughfall and precipitation, suggests high proportion of dry deposition in winter (up to 53%) as compared to summer (1–9%). However, a 3.5‰ decrease in δ18O–SO4 throughfall in summer compared to incident precipitation points towards a much larger proportion of dry deposition during the warm season. We suggest that a significant fraction of dry deposition (about 1.2 kg ha−1 yr−1, representing 30–40% of annual wet S deposition) which contributed to the decreased δ18O–SO4 in throughfall was taken up by the canopy. Overall, these results showed that, contrary to what is commonly considered, S interchanges in the canopy could be important in boreal forests with low absolute atmospheric S depositions. - Highlights: ► We investigated sulphur interactions with the canopy of two boreal forests, Québec. ► Sulphur interchanges within the canopy were large and vary with seasons. ► About 1.2 kg S–SO4 ha−1 yr−1 was taken up by the canopy during warm seasons. ► This represents 30–40% of annual wet S–SO4 deposition. ► Canopy uptake must be considered for sulphur budget estimations in boreal forests. - The equivalent of 30–40% of annual wet S–SO4 deposition was taken up by the canopy of two boreal forests during warm seasons.

  4. A new empirical method to predict carbon dioxide evasion from boreal lakes

    Science.gov (United States)

    Hastie, Adam; Lauerwald, Ronny; Weyhenmeyer, Gesa; Sobek, Sebastian; Regnier, Pierre

    2016-04-01

    Carbon dioxide evasion from lakes (F CO2) is an important component of the global carbon budget. In this study, empirical models have been developed to predict CO2 partial pressure (pCO2) in boreal lakes at the 0.5° grid scale, with the aim of producing the first map of F CO2 from these high latitude aquatic systems. Approximately 57,000 samples of lake pCO2 from Sweden and Finland were used to train the models. Significant seasonality in pCO2 was identified and thus data were split into two categories based on water temperature; 0-4.5° C and >4.5° C. The lake pCO2 data and various globally available, environmental parameters such as elevation, terrestrial net primary production (NPP) and climate (temperature T, rainfall R) were spatially aggregated to a 0.5° resolution. Preliminary results from multiple regression analyses suggest that a significant proportion of the variability in boreal lake pCO2 can be explained using these globally available parameters. For water temperatures above 4.5° C, the explained proportion of the variability in lake pCO2 is particularly high (r2= 0.7). Following further refinement and validation, a map of estimated lake pCO2 for the entire boreal region will be established. This map will then be combined with lake surface area data from the GLObal WAter BOdies database (GLOWABO, Verpoorter et al., 2014), and a calculation of gas exchange velocity k to produce the first map of boreal lake F CO2. Finally, IPCC projections of the selected environmental predictors (T, NPP, and R) will be used to estimate future F CO2 from boreal lakes and their sensitivity to climate change.

  5. Decomposition of soil organic matter from boreal black spruce forest: Environmental and chemical controls

    Science.gov (United States)

    Wickland, K.P.; Neff, J.C.

    2008-01-01

    Black spruce forests are a dominant covertype in the boreal forest region, and they inhabit landscapes that span a wide range of hydrologic and thermal conditions. These forests often have large stores of soil organic carbon. Recent increases in temperature at northern latitudes may be stimulating decomposition rates of this soil carbon. It is unclear, however, how changes in environmental conditions influence decomposition in these systems, and if substrate controls of decomposition vary with hydrologic and thermal regime. We addressed these issues by investigating the effects of temperature, moisture, and organic matter chemical characteristics on decomposition of fibric soil horizons from three black spruce forest sites. The sites varied in drainage and permafrost, and included a "Well Drained" site where permafrost was absent, and "Moderately well Drained" and "Poorly Drained" sites where permafrost was present at about 0.5 m depth. Samples collected from each site were incubated at five different moisture contents (2, 25, 50, 75, and 100% saturation) and two different temperatures (10??C and 20??C) in a full factorial design for two months. Organic matter chemistry was analyzed using pyrolysis gas chromatography-mass spectrometry prior to incubation, and after incubation on soils held at 20??C, 50% saturation. Mean cumulative mineralization, normalized to initial carbon content, ranged from 0.2% to 4.7%, and was dependent on temperature, moisture, and site. The effect of temperature on mineralization was significantly influenced by moisture content, as mineralization was greatest at 20??C and 50-75% saturation. While the relative effects of temperature and moisture were similar for all soils, mineralization rates were significantly greater for samples from the "Well Drained" site compared to the other sites. Variations in the relative abundances of polysaccharide-derivatives and compounds of undetermined source (such as toluene, phenol, 4-methyl phenol, and

  6. Impact of forest harvesting on water quality and fluorescence characteristics of dissolved organic matter in eastern Canadian Boreal Shield lakes in summer

    Science.gov (United States)

    Glaz, P.; Gagné, J.-P.; Archambault, P.; Sirois, P.; Nozais, C.

    2015-12-01

    Forestry activities in the Canadian Boreal region have increased in the last decades, raising concerns about their potential impact on aquatic ecosystems. Water quality and fluorescence characteristics of dissolved organic matter (DOM) were measured over a 3-year period in eight eastern Boreal Shield lakes: four lakes were studied before, 1 and 2 years after forest harvesting (perturbed lakes) and compared with four undisturbed reference lakes (unperturbed lakes) sampled at the same time. ANOVAs showed a significant increase in total phosphorus (TP) in perturbed lakes when the three sampling dates were considered and in DOC concentrations when considering 1 year before and 1 year after the perturbation only. At 1 year post-clear cutting DOC concentrations were about 15 % greater in the perturbed lakes at ~ 15 mgC L-1 compared to 12.5 mgC L-1 in the unperturbed lakes. In contrast, absorbance and fluorescence measurements showed that all metrics remained within narrow ranges compared to the range observed in natural waters, indicating that forest harvesting did not affect the nature of DOM characterized with spectroscopic techniques. These results confirm an impact of forestry activities 1 year after the perturbation. However, this effect seems to be mitigated 2 years after, indicating that the system shows high resilience and may be able to return to its original condition in terms of water quality parameters assessed in this study.

  7. Dichlobenil and 2,6-dichlorobenzamide (BAM) dissipation in topsoil and deposits from groundwater environment within the boreal region in southern Finland.

    Science.gov (United States)

    Pukkila, Veera; Kontro, Merja H

    2014-02-01

    BAM (2,6-dichlorobenzamide) is a metabolite of pesticide dichlobenil and a common groundwater contaminant. Dichlobenil and BAM half-lives were determined in five Finnish subsurface deposits and in topsoil. Aerobic and anaerobic conditions with sterilized controls were included in this 1.4-year incubation experiment. In subsurface deposits, dichlobenil half-life varied from 157 days to no degradation and that of BAM from 314 days to no degradation. Microbes and oxygen enhanced dichlobenil and BAM dissipation rates in some deposits. However, dichlobenil and BAM concentrations were most significantly affected by deposit characteristics, especially carbon and nitrogen amounts. Also low pH, cadmium, iron, zinc, manganese and lead correlated with low dichlobenil and/or BAM concentrations. In mineral topsoil, dissipation was faster with half-lives of 41-54 days for dichlobenil, and 182-261 days for BAM. Dichlobenil was depleted completely in surface soil, but BAM was not dissipated below 55-81 % of the initial concentration. Generally, dichlobenil and BAM dissipation in samples from the northern boreal region was similar to that reported for the temperate region. BAM was persistent in topsoil and subsurface deposits, indicating long-term persistence problems in groundwater also within the northern boreal region. PMID:24057965

  8. Drought tolerance and growth in populations of a wide-ranging tree species indicate climate change risks for the boreal north.

    Science.gov (United States)

    Montwé, David; Isaac-Renton, Miriam; Hamann, Andreas; Spiecker, Heinrich

    2016-02-01

    Choosing drought-tolerant planting stock in reforestation programs may help adapt forests to climate change. To inform such reforestation strategies, we test lodgepole pine (Pinus contorta Doug. ex Loud. var latifolia Englm.) population response to drought and infer potential benefits of a northward transfer of seeds from drier, southern environments. The objective is addressed by combining dendroecological growth analysis with long-term genetic field trials. Over 500 trees originating from 23 populations across western North America were destructively sampled in three experimental sites in southern British Columbia, representing a climate warming scenario. Growth after 32 years from provenances transferred southward or northward over long distances was significantly lower than growth of local populations. All populations were affected by a severe natural drought event in 2002. The provenances from the most southern locations showed the highest drought tolerance but low productivity. Local provenances were productive and drought tolerant. Provenances from the boreal north showed lower productivity and less drought tolerance on southern test sites than all other sources, implying that maladaptation to drought may prevent boreal populations from taking full advantage of more favorable growing conditions under projected climate change. PMID:26463121

  9. Variations in fire severity and frequency as a driver of changes in succession and long-term patterns of carbon storage in Alaskan boreal forests

    Science.gov (United States)

    Johnstone, J.; Kasischke, E. S.; Bourgeau-Chavez, L.; Chapin, F. S.

    2005-12-01

    Black spruce is the dominant forest cover type in the North American boreal region (they represent some 57 percent of all forests in this region). These spruce forests are a major North American terrestrial carbon reservoir because cold ground temperatures lead to low decomposition rates and the building up of carbon-rich layers of dead organic matter over century and longer time scales. The surface organic layers and living vegetation of these forests contain an estimated 22.6 Gt of carbon, with nearly two-thirds of this amount stored in the surface organic layer lying on top of mineral soil. There has been a significant increase in fire activity the boreal forest region of North America, with annual area burned doubling between the 1960s and 1990s in association with warming climates. This rise in temperature and disturbance from fire brings into question the fate of the large carbon reservoir present in the black spruce forests of this region. Here we present a conceptual framework based on a state-factors model that can be used to examine how variations in the fire regime alter successional pathways and carbon storage in the black spruce forests of Alaska. In particular, we focus on the factors and site conditions that will allow black spruce forests to switch to successional trajectories containing a significant deciduous component. To illustrate the concepts presented in this framework, results from recent research will be presented.

  10. Radiation regime and canopy architecture in a boreal aspen forest

    International Nuclear Information System (INIS)

    This study was part of the Boreal Ecosystem-Atmosphere Study (BOREAS). It took place in a mature aspen forest in Prince Albert National Park, Saskatchewan, Canada. The aspen trees were 21.5 m high with a 2–3 m high hazelnut understory. The objectives were: (1) to compare the radiation regime beneath the overstory before and after leaf emergence; (2) to infer the structural characteristics of the aspen canopy leaf inclination and clumping; (3) to determine the seasonal course of the leaf area index (L) for both the overstory and understory. Above-stand radiation measurements were made on a 39m walk-up tower, and understory radiation measurements were made on a tram which moved horizontally back and forth at 0.10 m s−1 on a pair of steel cables 65m in length suspended 4 m above the ground. In addition, several LI-COR LAI-2000 Plant Canopy Analyzers were used to determine the effective leaf area index and the zenith angle dependent extinction coefficient (G(θ)) for both the aspen and the hazelnut throughout the growing season. These measurements were supplemented with destructive sampling of the hazelnut at the peak of the growing season. Before leaf emergence, the ratios of below- to above-aspen solar radiation (S), photosynthetic photon flux density (PPFD) and net radiation (Rn) during most of the day were 0.58, 0.55 and 0.47, respectively. By midsummer, these ratios had fallen to 0.33, 0.26 and 0.26, respectively. The aspen G(θ) was relatively invariant with θ, within ±0.05 of 0.5 throughout the growing season, indicating a spherical distribution of leaf inclination angles (i.e. the leaves were randomly inclined). The hazelnut G(θ) has a cosine response with respect to θ, which was consistent with the generally planophile leaf distribution for hazelnut. Using canopy gap size distribution theories developed by Chen and Black (1992b, Agric. For. Meteorol., 60: 249–266) and Chen and Cihlar (1995a, Appl. Opt., 34: 6211–6222) based on Miller and Norman

  11. The impact of bryophytes on the carbon stocks of northern boreal forest soils

    Science.gov (United States)

    Hagemann, U.; Moroni, M. T.; Shaw, C. H.; Kurz, W. A.

    2012-04-01

    Dead organic matter (DOM), organic layer, and mineral soil carbon (C) dynamics in cool and humid northern boreal forests are expected to differ from those of drier or warmer boreal forests, because processes such as paludification and woody debris (WD) burial within the organic layer by overgrowing moss are more pronounced in regions with low average temperatures, vigorous moss layers, and long fire-return intervals. However, very few studies have provided field-measured data for these mostly remote regions. Hence, C cycling models such as the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) have rarely been validated with field data from northern boreal forest soils, resulting in large uncertainties for estimated C stocks in a large proportion of the boreal forest ecozone. We present (i) measured data on organic layer and mineral soil (0-45 cm) C stocks in 18 old-growth and disturbed high-boreal black spruce stands in Labrador, Canada; (ii) a comparison of field-measured soil C stocks with those predicted using the CBM-CFS3; and (iii) special characteristics of the DOM and soil C dynamics of northern boreal forest soils that require modifications of model parameters and structure. Measured organic layer C stocks (30.4-47.4 Mg C ha-1) were within the range reported for other boreal forests. However, mineral soil C stocks (121.5-208.1 Mg C ha-1) contributed 58-76% to total ecosystem C stocks. Mineral soil C stocks were thus considerably higher than observed in other upland boreal forests in drier or warmer regions, but similar to values reported for black spruce on poorly drained sites and peat soils. In addition, large amounts of deadwood C (4.7-18.2 Mg C ha-1) were found to be buried within the organic layer, contributing up to 31% to total organic layer C stocks. The comparison of field-measured and CBM-CFS3 modeled C stocks showed that organic layer and mineral soil DOM in Labrador black spruce stands likely decays at lower rates than assumed by CBM

  12. Modeling regional to global CH4 emissions of boreal and arctic wetlands

    Science.gov (United States)

    Petrescu, A. M. R.; van Beek, L. P. H.; van Huissteden, J.; Prigent, C.; Sachs, T.; Corradi, C. A. R.; Parmentier, F. J. W.; Dolman, A. J.

    2010-12-01

    Methane (CH4) emission from boreal, arctic and subarctic wetlands constitutes a potentially positive feedback to global climate warming. Many process-based models have been developed, but high uncertainties remain in estimating the amount of CH4 released from wetlands at the global scale. This study tries to improve estimates of CH4 emissions by up-scaling a wetland CH4 emission model, PEATLAND-VU, to the global scale with a spatial resolution of 0.5° for the period 2001-2006. This up-scaling was based on the global circum-arctic distribution of wetlands with hydrological conditions being specified by a global hydrological model, PCR-GLOBWB. In addition to the daily hydrological output from PCR-GLOBWB, comprising water table depths and snow thickness, the parameterization included air temperature as obtained from the ECMWF Operational Archive. To establish the uncertainty in the representations of the circum-arctic distribution of wetlands on the CH4 emission, several existing products were used to aggregate the emissions. Using the description of potential peatlands from the FAO Digital Soil Map of the World and the representation of floodplains by PCR-GLOBWB, the average annual flux over the period 2001-2006 was estimated to be 78 Tg yr-1. In comparison, the six-year average CH4 fluxes were 37.7, 89.4, 145.6, and 157.3 Tg yr-1 for different estimates of wetland extends based on the studies by Matthews and Fung, Prigent et al., Lehner and Döll, and Kaplan, respectively. This study shows the feasibility to estimate interannual variations in CH4 emissions by coupling hydrological and CH4 emission process models. It highlights the importance of an adequate understanding of hydrology in quantifying the total emissions from northern hemispheric wetlands and shows how knowledge of the sub-grid variability in wetland extent helps to prescribe relevant hydrological conditions to the emission model as well as to identify the uncertainty associated with existing wetland

  13. Assessing various drought indicators in representing drought in boreal forests in Finland

    Science.gov (United States)

    Gao, Y.; Markkanen, T.; Thum, T.; Aurela, M.; Lohila, A.; Mammarella, I.; Hagemann, S.; Aalto, T.

    2015-08-01

    Droughts can impact on forest functioning and production, and even lead to tree mortality. However, drought is an elusive phenomenon that is difficult to quantify and define universally. In this study, we assessed the performance of a set of indicators that have been used to describe drought conditions in the summer months (June, July, August) over a 30 year period (1981-2010) in Finland. Those indicators include the Standardized Precipitation Index (SPI), the Standardized Precipitation-Evapotranspiration Index (SPEI), the Soil Moisture Index (SMI) and the Soil Moisture Anomaly (SMA). Herein, regional soil moisture was produced by the land surface model JSBACH. While SPI, SPEI, and SMA show a degree of anomalies from the statistical means over a period, SMI is directly connected to plant available water and closely dependent on soil properties. Moreover, the buffering effect of soil moisture and the associated soil moisture memory can impact on the onset and duration of drought as indicated by the SMI and SMA, whereas SPI and SPEI are directly controlled by meteorological conditions. In particular, we investigated whether the SMI, SMA and SPEI are able to indicate the Extreme Drought affecting Forest health (EDF) in Finland. EDF thresholds for these indicators are suggested, based on the spatially representative statistics of forest health observations in the exceptional dry year 2006. Our results showed that SMI was the best indicator in capturing the spatial extent of forest damage induced by the extreme drought in 2006. In addition, the derived thresholds were applied to those indicators to capture EDF events over the summer months of the 30 year study period. The SPEI and SMA showed more frequent EDF events over the 30 year period, and typically described a higher fraction of influenced area than SMI. In general, the suggested EDF thresholds for those indicators may be used for the indication of EDF events in Finland or other boreal forests areas in the context

  14. Assessing various drought indicators in representing drought in boreal forests in Finland

    Directory of Open Access Journals (Sweden)

    Y. Gao

    2015-08-01

    Full Text Available Droughts can impact on forest functioning and production, and even lead to tree mortality. However, drought is an elusive phenomenon that is difficult to quantify and define universally. In this study, we assessed the performance of a set of indicators that have been used to describe drought conditions in the summer months (June, July, August over a 30 year period (1981–2010 in Finland. Those indicators include the Standardized Precipitation Index (SPI, the Standardized Precipitation–Evapotranspiration Index (SPEI, the Soil Moisture Index (SMI and the Soil Moisture Anomaly (SMA. Herein, regional soil moisture was produced by the land surface model JSBACH. While SPI, SPEI, and SMA show a degree of anomalies from the statistical means over a period, SMI is directly connected to plant available water and closely dependent on soil properties. Moreover, the buffering effect of soil moisture and the associated soil moisture memory can impact on the onset and duration of drought as indicated by the SMI and SMA, whereas SPI and SPEI are directly controlled by meteorological conditions. In particular, we investigated whether the SMI, SMA and SPEI are able to indicate the Extreme Drought affecting Forest health (EDF in Finland. EDF thresholds for these indicators are suggested, based on the spatially representative statistics of forest health observations in the exceptional dry year 2006. Our results showed that SMI was the best indicator in capturing the spatial extent of forest damage induced by the extreme drought in 2006. In addition, the derived thresholds were applied to those indicators to capture EDF events over the summer months of the 30 year study period. The SPEI and SMA showed more frequent EDF events over the 30 year period, and typically described a higher fraction of influenced area than SMI. In general, the suggested EDF thresholds for those indicators may be used for the indication of EDF events in Finland or other boreal forests

  15. Seasonal Effects of Habitat on Sources and Rates of Snowshoe Hare Predation in Alaskan Boreal Forests.

    Directory of Open Access Journals (Sweden)

    Dashiell Feierabend

    Full Text Available Survival and predation of snowshoe hares (Lepus americanus has been widely studied, yet there has been little quantification of the changes in vulnerability of hares to specific predators that may result from seasonal changes in vegetation and cover. We investigated survival and causes of mortalities of snowshoe hares during the late increase, peak, and decline of a population in interior Alaska. From June 2008 to May 2012, we radio-tagged 288 adult and older juvenile hares in early successional and black spruce (Picea mariana forests and, using known-fate methods in program MARK, evaluated 85 survival models that included variables for sex, age, and body condition of hares, as well as trapping site, month, season, year, snowfall, snow depth, and air temperature. We compared the models using Akaike's information criterion with correction for small sample size. Model results indicated that month, capture site, and body condition were the most important variables in explaining survival rates. Survival was highest in July, and more generally during summer, when alternative prey was available to predators of hares. Low survival rates coincided with molting periods, breeding activity in the spring, and the introduction of juveniles to the sample population in the fall. We identified predation as the cause of mortality in 86% of hare deaths. When the source of predation could be determined, hares were killed more often by goshawks (Accipiter gentilis than other predators in early successional forest (30%, and more often by lynx (Lynx canadensis than other predators in black spruce forest (31%. Great horned owls (Bubo virginianus and coyotes (Canis latrans represented smaller proportions of hare predation, and non-predatory causes were a minor source (3% of mortality. Because hares rely on vegetative cover for concealment from predators, we measured cover in predation sites and habitats that the hares occupied and concluded that habitat type had a

  16. Short-term effects of thinning, clear-cutting and stump harvesting on methane exchange in a boreal forest

    Directory of Open Access Journals (Sweden)

    E. Sundqvist

    2014-03-01

    Full Text Available Forest management practices can alter soil conditions, affecting the consumption and production processes that control soil methane (CH4 exchange. We studied the short-term effects of thinning, clear-cutting and stump harvesting on the CH4 exchange between soil and atmosphere at a boreal forest site in central Sweden, using an undisturbed plot as the control. Chambers in combination with a high precision laser gas analyser were used for continuous measurements. Both the undisturbed plot and the thinned plot were net sinks of CH4, whereas the clear-cut plot and the stump harvested plot were net CH4 sources. The CH4 uptake at the thinned plot was reduced in comparison to the undisturbed plot. The shift from sink to source at the clear-cut and stump harvested plots was probably due to a rise of the water table and an increase in soil moisture, leading to lower gas diffusivity and more reduced conditions which favour CH4 production by archea. Reduced evapotranspiration after harvesting leads to wetter soils, decreased CH4 consumption and increased CH4 production, and should be accounted for in the CH4 budget of managed forests.

  17. Climate change alters the structure of arctic marine food webs due to poleward shifts of boreal generalists

    OpenAIRE

    Kortsch, Susanne; Primicerio, Raul; Fossheim, Maria; Dolgov, Andrey V.; Aschan, Michaela

    2015-01-01

    Climate-driven poleward shifts, leading to changes in species composition and relative abundances, have been recently documented in the Arctic. Among the fastest moving species are boreal generalist fish which are expected to affect arctic marine food web structure and ecosystem functioning substantially. Here, we address structural changes at the food web level induced by poleward shifts via topological network analysis of highly resolved boreal and arctic food webs of the ...

  18. The role of soil pH in linking groundwater flow and plant species density in boreal forest landscapes

    OpenAIRE

    Zinko, Ursula; Dynesius, Mats; Nilsson, Christer; Seibert, Jan

    2006-01-01

    In hilly boreal landscapes topography governs groundwater flow which strongly influences soil development, and thus vegetation composition. Soil pH is known to correlate well with plant species density and composition, but in boreal forests this relationship has been little studied. Previously, we successfully used a topography-based hydrological index, the topographical wetness index (TWI), as an approximation of the variation in groundwater flow to predict local plant species density in a b...

  19. Differences in satellite-derived NOx emission factors between Eurasian and North American boreal forest fires

    Science.gov (United States)

    Schreier, S. F.; Richter, A.; Schepaschenko, D.; Shvidenko, A.; Hilboll, A.; Burrows, J. P.

    2015-11-01

    Current fire emission inventories apply universal emission factors (EFs) for the calculation of NOx emissions over large biomes such as boreal forest. However, recent satellite-based studies over tropical and subtropical regions have indicated spatio-temporal variations in EFs within specific biomes. In this study, satellite measurements of tropospheric NO2 vertical columns (TVC NO2) from the GOME-2 instrument and fire radiative power (FRP) from MODIS are used for the estimation of fire emission rates (FERs) of NOx over Eurasian and North American boreal forests. The retrieval of TVC NO2 is based on a stratospheric correction using simulated stratospheric NO2 instead of applying the reference sector method, which was used in a previous study. The model approach is more suitable for boreal latitudes. TVC NO2 and FRP are spatially aggregated to a 1° × 1° horizontal resolution and temporally averaged to monthly values. The conversion of the satellite-derived tropospheric NO2 columns into production rates of NOx from fire (Pf) is based on the NO2/NOx ratio as obtained from the MACC reanalysis data set and an assumed lifetime of NOx. A global land cover map is used to define boreal forests across these two regions in order to evaluate the FERs of NOx for this biome. The FERs of NOx, which are derived from the gradients of the linear relationship between Pf and FRP, are more than 30% lower for North American than for Eurasian boreal forest fires. We speculate that these discrepancies are mainly related to the variable nitrogen content in plant tissues, which is higher in deciduous forests dominating large parts in Eurasia. In order to compare the obtained values with EFs found in the literature, the FERs are converted into EFs. The satellite-based EFs of NOx are estimated at 0.83 and 0.61 g kg-1 for Eurasian and North American boreal forests, respectively, which is in good agreement with the value found in a recent emission factor compilation. However, recent fire

  20. Sources and sinks of carbon in boreal ecosystems of interior Alaska: a review

    Science.gov (United States)

    Douglas, Thomas A.; Jones, Miriam C.; Hiemstra, Christopher A.

    2014-01-01

    Boreal regions store large quantities of carbon but are increasingly vulnerable to carbon loss due to disturbance and climate warming. The boreal region, underlain by discontinuous permafrost, presents a challenging landscape for itemizing current and potential carbon sources and sinks in the boreal soil and vegetation. The roles of fire, forest succession, and the presence (or absence) of permafrost on carbon cycle, vegetation, and hydrologic processes have been the focus of multidisciplinary research in this area for the past 20 years. However, projections of a warming future climate, an increase in fire severity and extent, and the potential degradation of permafrost could lead to major landscape process changes over the next 20 to 50 years. This provides a major challenge for predicting how the interplay between land management activities and impacts of climate warming will affect carbon sources and sinks in Interior Alaska. To assist land managers in adapting and managing for potential changes in the Interior Alaska carbon cycle we developed this review paper incorporating an overview of the climate, ecosystem processes, vegetation types, and soil regimes in Interior Alaska with a focus on ramifications for the carbon cycle. Our objective is to provide a synthesis of the most current carbon storage estimates and measurements to support policy and land management decisions on how to best manage carbon sources and sinks in Interior Alaska. To support this we have surveyed relevant peer reviewed estimates of carbon stocks in aboveground and belowground biomass for Interior Alaska boreal ecosystems. We have also summarized methane and carbon dioxide fluxes from the same ecosystems. These data have been converted into the same units to facilitate comparison across ecosystem compartments. We identify potential changes in the carbon cycle with climate change and human disturbance including how compounding disturbances can affect the boreal system. Finally, we provide

  1. Changes in microbial decomposition across a fire chronosequence in Alaskan boreal forests

    Science.gov (United States)

    Holden, S. R.; Treseder, K. K.

    2012-12-01

    Climate warming in boreal forests is likely to increase the frequency and severity of wildfires, with uncertain consequences for soil microbial communities and soil carbon dynamics. This uncertainty is germane because an estimated 90-290 Pg carbon resides in the soils of boreal forests, accounting for 12-42% of global soil organic carbon. Previous work suggests that fires stimulate microbial decomposition, in part due to post-fire increases in soil temperature. However, this hypothesis has rarely been directly tested in a field setting. The objectives of this study were (1) to quantify changes in microbial decomposition following boreal forest fires and (2) to elucidate the mechanisms controlling post-fire changes in microbial decomposition. To address objective 1, we measured the decomposition rate of aspen and black spruce litter across a fire chronosequence in boreal forests of interior Alaska. This fire chronosequence contains sites that burned in 2010, 2004, 1999, 1987, and two "control" sites that are ~100 years old. After one year of decomposition, aspen and black spruce litter decomposing at recently burned sites lost significantly less mass in comparison to mature stands. Decomposition rates increased with the time since fire (Aspen: r2 = 0.691, P microbial biomass (P = 0.005) and lower hydrolytic extracellular enzyme activity (P = 0.001) than mature stands. To address objective 2, we set up a reciprocal transplant to isolate the effects of the soil environment, organic matter origin, and microbial community origin on post-fire microbial decomposition. These main effects were crossed in a full factorial design with two levels of each factor (burned or unburned). We found that organic matter decomposing at a recently burned site lost significantly less mass than organic matter decomposing at an unburned site (P = 0.029), regardless of the organic matter origin or microbial community origin. Overall, we found no evidence that boreal wildfires stimulate

  2. Adapting fire management to future fire regimes: impacts on boreal forest composition and carbon balance in Canadian National Parks

    Science.gov (United States)

    de Groot, W. J.; Flannigan, M. D.; Cantin, A.

    2009-04-01

    The effects of future fire regimes altered by climate change, and fire management in adaptation to climate change were studied in the boreal forest region of western Canada. Present (1975-90) and future (2080-2100) fire regimes were simulated for several National Parks using data from the Canadian (CGCM1) and Hadley (HadCM3) Global Climate Models (GCM) in separate simulation scenarios. The long-term effects of the different fire regimes on forests were simulated using a stand-level, boreal fire effects model (BORFIRE). Changes in forest composition and biomass storage due to future altered fire regimes were determined by comparing current and future simulation results. This was used to assess the ecological impact of altered fire regimes on boreal forests, and the future role of these forests as carbon sinks or sources. Additional future simulations were run using adapted fire management strategies, including increased fire suppression and the use of prescribed fire to meet fire cycle objectives. Future forest composition, carbon storage and emissions under current and adapted fire management strategies were also compared to determine the impact of various future fire management options. Both of the GCM's showed more severe burning conditions under future fire regimes. This includes fires with higher intensity, greater depth of burn, greater total fuel consumption and shorter fire cycles (or higher rates of annual area burned). The Canadian GCM indicated burning conditions more severe than the Hadley GCM. Shorter fire cycles of future fire regimes generally favoured aspen, birch, and jack pine because it provided more frequent regeneration opportunity for these pioneer species. Black spruce was only minimally influenced by future fire regimes, although white spruce declined sharply. Maintaining representation of pure and mixed white spruce ecosystems in natural areas will be a concern under future fire regimes. Active fire suppression is required in these areas. In

  3. Response of CH4 emission to moss removal and N addition in boreal peatland of Northeast China

    Directory of Open Access Journals (Sweden)

    H. N. Meng

    2014-02-01

    Full Text Available Boreal peatlands are an important natural source of atmospheric methane (CH4. Recently, boreal peatlands have been experiencing increased nitrogen (N input and decreased moss production. However, little is known about the interactive effect of moss and N availability on CH4 emission in boreal peatlands. In this study, the effects of moss removal and N addition (6 g N m−2 yr−1 on CH4 emission were examined during the growing seasons of 2011 to 2013 in a boreal peatland in the Great Hinggan Mountain of Northeast China. Notably, the response of CH4 emission to moss removal and N addition varied with experimental duration. Moss removal and N addition did not affect CH4 emission in 2011 and 2012, but respectively declined CH4 emission by 50% and 66% in 2013. However, moss removal and N addition did not produce an interactive effect on CH4 emission. Specifically, moss removal plus N addition had no effect on CH4 emission in 2011 and 2012, but decreased CH4 emission by 68% in 2013. These results suggest that the effects of moss removal and N enrichment on CH4 emission are time-dependent in boreal peatlands, and also imply that increased N loading and decreased moss growth would independently inhibit CH4 emission in the boreal peatlands of Northeast China.

  4. Recent NDVI-Based Variation in Growth of Boreal Intact Forest Landscapes and Its Correlation with Climatic Variables

    Directory of Open Access Journals (Sweden)

    Jiaxin Jin

    2016-04-01

    Full Text Available Intact Forest Landscape (IFL is of great value in protecting biodiversity and supporting core ecological processes. It is important to analyze the spatial variation in the growth dynamics of IFL. This study analyzed the change of the Normalized Difference Vegetation Index (NDVI during the growing season (April–October for boreal (45° N–70° N IFLs and the correlation with climatic variables over the period of 2000–2013. Our results show 85.5% of boreal IFLs did not show a significant change in the NDVI after 2000, and only 10.2% and 4.3% exhibited a statistically significant increase (greening or decrease (browning in NDVI, respectively. About 60.9% of the greening boreal IFLs showed that an increasing NDVI was significantly correlated to climatic variables, especially an increasing growing season temperature (over 47.0%. For browning boreal IFLs, a decrease in temperature or an increase in dormancy period precipitation could be the prime reason for a significant decrease in the NDVI. However, about 64.6% of the browning boreal IFLs were insensitive to any of the climatic variables, indicating other factors, such as fire, had caused the browning. Although it did not show a significant trend, the NDVI of 51.3% of no-change boreal IFLs significantly correlated to climatic variables, especially growing season temperatures (over 37.6%.

  5. Modulation of the boreal wintertime Madden-Julian oscillation by the stratospheric quasi-biennial oscillation

    Science.gov (United States)

    Yoo, Changhyun; Son, Seok-Woo

    2016-02-01

    Madden-Julian oscillation (MJO), the dominant mode of intraseasonal variability in the tropical troposphere, has a significant impact on global weather and climate. Here we present that the year-to-year variation of the MJO activity shows significant changes with the quasi-biennial oscillation (QBO) in the tropical stratosphere. Specifically, the boreal winter MJO amplitude, evaluated by various metrics, is typically stronger than normal during the QBO easterly phase at 50 hPa and weaker than normal during the QBO westerly phase at 50 hPa. This relationship, which is possibly mediated by the QBO-related static stability and/or vertical wind shear changes in the tropical upper troposphere and lower stratosphere, is robust whether or not the activeness of the MJO or QBO is taken into account. This result suggests a new potential route from the stratosphere that regulates the organized tropical convection, helping to improve the prediction skill of the boreal winter MJO.

  6. In search of a critical habitat concept for woodland caribou, boreal population

    Directory of Open Access Journals (Sweden)

    Gerald D. Racey

    2007-04-01

    Full Text Available A hierarchical approach to critical habitat identification has been proposed in the draft National Recovery Strategy for the Woodland Caribou (Rangifer tarandus caribou, Boreal Population. This approach proposes that critical habitat for boreal caribou be identified as equivalent with caribou ranges and their composite range components, and that it be consistent with the biological needs of a wild, self-sustaining local population of woodland caribou. These components include seasonal ranges, high use areas and calving sites, each of which provide for important ecological functions and are subject to specific risks from human development activities. Protection of critical habitat is accomplished through management of the amount and type of human developments and potential natural disturbances, not by prohibiting all activity. This approach to critical habitat sets the stage for management and monitoring of habitat at spatial and temporal scales appropriate for conservation of a wide ranging species such as woodland caribou.

  7. Offset of the potential carbon sink from boreal forestation by decreases in surface albedo

    International Nuclear Information System (INIS)

    Carbon uptake by forestation is one method proposed to reduce net carbon dioxide emissions to the atmosphere and so limit the radiative forcing of climate change. But the overall impact of forestation on climate will also depend on other effects associated with the creation of new forests. In particular the albedo of a forested landscape is generally lower than that of cultivated land, especially when snow is lying, and decreasing albedo exerts a positive radiative forcing on climate. Here I simulate the radiative forcings associated with changes in surface albedo as a result of forestation in temperate and boreal forest areas, and translate these forcings into equivalent changes in local carbon stock for comparison with estimated carbon sequestration potentials. I suggest that in many boreal forest areas, the positive forcing induced by decreases in albedo can offset the negative forcing that is expected from carbon sequestration. Some high-latitude forestation activities may therefore increase climate change, rather that mitigating it as intended

  8. Arctic and boreal ecosystems of western North America as components of the climate system

    Science.gov (United States)

    Chapin, F. S., III; McGuire, A.D.; Randerson, J.; Pielke, R., Sr.; Baldocchi, D.; Hobbie, S.E.; Roulet, Nigel; Eugster, W.; Kasischke, E.; Rastetter, E.B.; Zimov, S.A.; Running, S.W.

    2000-01-01

    Synthesis of results from several Arctic and boreal research programmes provides evidence for the strong role of high-latitude ecosystems in the climate system. Average surface air temperature has increased 0.3??C per decade during the twentieth century in the western North American Arctic and boreal forest zones. Precipitation has also increased, but changes in soil moisture are uncertain. Disturbance rates have increased in the boreal forest; for example, there has been a doubling of the area burned in North America in the past 20 years. The disturbance regime in tundra may not have changed. Tundra has a 3-6-fold higher winter albedo than boreal forest, but summer albedo and energy partitioning differ more strongly among ecosystems within either tundra or boreal forest than between these two biomes. This indicates a need to improve our understanding of vegetation dynamics within, as well as between, biomes. If regional surface warming were to continue, changes in albedo and energy absorption would likely act as a positive feedback to regional warming due to earlier melting of snow and, over the long term, the northward movement of treeline. Surface drying and a change in dominance from mosses to vascular plants would also enhance sensible heat flux and regional warming in tundra. In the boreal forest of western North America, deciduous forests have twice the albedo of conifer forests in both winter and summer, 50-80% higher evapotranspiration, and therefore only 30-50% of the sensible heat flux of conifers in summer. Therefore, a warming-induced increase in fire frequency that increased the proportion of deciduous forests in the landscape, would act as a negative feedback to regional warming. Changes in thermokarst and the aerial extent of wetlands, lakes, and ponds would alter high-latitude methane flux. There is currently a wide discrepancy among estimates of the size and direction of CO2 flux between high-latitude ecosystems and the atmosphere. These

  9. Regional-scale surface flux observations across the boreal forest during BOREAS

    DEFF Research Database (Denmark)

    Oncley, S.P.; Lenschow, D.H.; Campos, T.L.; Davis, K.J.; Mann, J.

    study area to the subarctic tundra. Typical midsummer, midday, large-scale net ecosystem exchanges of carbon dioxide were about -10 mu mol m(-2) s(-1) for primarily deciduous forests, about -6 mu mol m(-2) s(-1) for the primarily coniferous regions between and including the two BOREAS study areas, and......A major role of the National Center for Atmospheric Research (NCAR) Electra aircraft during the Boreal Ecosystem-Atmosphere Study (BOREAS) was to measure fluxes of momentum, sensible and latent heat, carbon dioxide, and ozone on a transect that crossed the entire boreal forest biome. The...... along the transect. Lakes are also found to be large sinks of available radiant energy. Regional ground storage of heat is estimated to be about 30% of the net radiation over the forest, and 40% over the subarctic tundra, largely due to the presence of lakes....

  10. Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest.

    Science.gov (United States)

    Hasselquist, Niles J; Metcalfe, Daniel B; Inselsbacher, Erich; Stangl, Zsofia; Oren, Ram; Näsholm, Torgny; Högberg, Peter

    2016-04-01

    The central role that ectomycorrhizal (EM) symbioses play in the structure and function of boreal forests pivots around the common assumption that carbon (C) and nitrogen (N) are exchanged at rates favorable for plant growth. However, this may not always be the case. It has been hypothesized that the benefits mycorrhizal fungi convey to their host plants strongly depends upon the availability of C and N, both of which are rapidly changing as a result of intensified human land use and climate change. Using large-scale shading and N addition treatments, we assessed the independent and interactive effects of changes in C and N supply on the transfer of N in intact EM associations with -15 yr. old Scots pine trees. To assess the dynamics of N transfer in EM symbioses, we added trace amounts of highly enriched 5NO3(-) label to the EM-dominated mor-layer and followed the fate of the 15N label in tree foliage, fungal chitin on EM root tips, and EM sporocarps. Despite no change in leaf biomass, shading resulted in reduced tree C uptake, ca. 40% lower fungal biomass on EM root tips, and greater 15N label in tree foliage compared to unshaded control plots, where more 15N label was found in fungal biomass on EM colonized root tips. Short-term addition of N shifted the incorporation of 15N label from EM fungi to tree foliage, despite no significant changes in below-ground tree C allocation to EM fungi. Contrary to the common assumption that C and N are exchanged at rates favorable for plant growth, our results show for the first time that under N-limited conditions greater C allocation to EM fungi in the field results in reduced, not increased, N transfer to host trees. Moreover, given the ubiquitous nature of mycorrhizal symbioses, our results stress the need to incorporate mycorrhizal dynamics into process-based ecosystem models to better predict forest C and N cycles in light of global climate change. PMID:27220217

  11. Seasonal and inter-annual variability of energy exchange above a boreal Scots pine forest

    Directory of Open Access Journals (Sweden)

    S. Launiainen

    2010-12-01

    Full Text Available Twelve-years of eddy-covariance measurements conducted above a boreal Scots pine forest in Hyytiälä, Southern Finland, were analyzed to assess the seasonal and inter-annual variability of surface conductance (gs and energy partitioning. The gs had distinct annual course, driven by the seasonal cycle of the Scots pine. Low gs (2–3 mm s−1 in April cause the sensible heat flux to peak in May–June while evapotranspiration takes over later in July–August when gs is typically 5–7 mm s−1. Hence, during normal years Bowen ratio decreases from 4–6 in April to 0.7–0.9 in August. Sensitivity of gs to ambient vapor pressure deficit (D was relatively constant but the reference value at D = 1 kPa varied seasonally and between years. Only two drought episodes when volumetric soil moisture content in upper mineral soil decreased below 0.15 m3 m−3 occurred during the period. Below this threshold value, transpiration was strongly reduced, which promoted sensible heat exchange increasing Bowen ratio to 3–4. Annual evapotranspiration varied between 218 and 361 mm and accounted between 50% and 90% of equilibrium evaporation. The forest floor contributed between 16 and 25% of the total evapotranspiration on annual scale. The fraction stayed similar over the observed range of environmental conditions including drought periods. The inter-annual variability of evapotranspiration could not be linked to any mean climate variable while the summertime sensible heat flux and net radiation were well explained by global radiation. The energy balance closure varied annually between 0.66 and 0.95 and had a distinct seasonal cycle with worse closure in spring when a large proportion of available energy is partitioned into sensible heat.

  12. The Uncertainty of Biomass Estimates from Modeled ICESat-2 Returns Across a Boreal Forest Gradient

    Science.gov (United States)

    Montesano, P. M.; Rosette, J.; Sun, G.; North, P.; Nelson, R. F.; Dubayah, R. O.; Ranson, K. J.; Kharuk, V.

    2014-01-01

    The Forest Light (FLIGHT) radiative transfer model was used to examine the uncertainty of vegetation structure measurements from NASA's planned ICESat-2 photon counting light detection and ranging (LiDAR) instrument across a synthetic Larix forest gradient in the taiga-tundra ecotone. The simulations demonstrate how measurements from the planned spaceborne mission, which differ from those of previous LiDAR systems, may perform across a boreal forest to non-forest structure gradient in globally important ecological region of northern Siberia. We used a modified version of FLIGHT to simulate the acquisition parameters of ICESat-2. Modeled returns were analyzed from collections of sequential footprints along LiDAR tracks (link-scales) of lengths ranging from 20 m-90 m. These link-scales traversed synthetic forest stands that were initialized with parameters drawn from field surveys in Siberian Larix forests. LiDAR returns from vegetation were compiled for 100 simulated LiDAR collections for each 10 Mg · ha(exp -1) interval in the 0-100 Mg · ha(exp -1) above-ground biomass density (AGB) forest gradient. Canopy height metrics were computed and AGB was inferred from empirical models. The root mean square error (RMSE) and RMSE uncertainty associated with the distribution of inferred AGB within each AGB interval across the gradient was examined. Simulation results of the bright daylight and low vegetation reflectivity conditions for collecting photon counting LiDAR with no topographic relief show that 1-2 photons are returned for 79%-88% of LiDAR shots. Signal photons account for approximately 67% of all LiDAR returns, while approximately 50% of shots result in 1 signal photon returned. The proportion of these signal photon returns do not differ significantly (p greater than 0.05) for AGB intervals greater than 20 Mg · ha(exp -1). The 50m link-scale approximates the finest horizontal resolution (length) at which photon counting LiDAR collection provides strong model

  13. Seasonal and inter annual variability of energy exchange above a boreal Scots pine forest

    Directory of Open Access Journals (Sweden)

    S. Launiainen

    2010-08-01

    Full Text Available Twelve-years of eddy-covariance measurements conducted above a boreal Scots pine forest in Hyytiälä, Southern Finland, were analyzed to assess the seasonal and inter-annual variability of surface conductance (gs and energy partitioning. The gs had distinct annual course, driven by the seasonal cycle of the Scots pine. Low gs (2–3 mm s−1 in April restricted transpiration in springtime and caused the sensible heat flux to peak in May–June while evapotranspiration takes over later in July–August when gs is typically 5–7 mm s−1. Hence, during normal years Bowen ratio decreases from 4–6 in April to 0.7–0.9 in August. Sensitivity of gs to ambient vapor pressure deficit (D was relatively constant but the reference value at D=1 kPa varied seasonally and between years. Only two drought episodes when volumetric soil moisture content in upper mineral soil decreased below 0.15 m3 m−3 occurred during the period. Below this threshold value transpiration was strongly reduced, which promoted sensible heat exchange increasing Bowen ratio to 3–4. Annual evapotranspiration varied between 218 and 361 mm and accounted between 50% and 90% of equilibrium evaporation. The forest floor contributed between 16 and 25% of the total evapotranspiration on annual scale. The fraction stayed similar over the observed range of environmental conditions including drought. The inter-annual variability of evapotranspiration could not be linked to any mean climate parameter while the summertime sensible heat flux and net radiation were well explained by global radiation. The energy balance closure varied annually between 0.66 and 0.95 and had a distinct seasonal cycle with worse closure in spring when large proportion of available energy is partitioned into sensible heat.

  14. Hydroxyl radical measurements and oxidation capacity in a boreal forest environment

    Science.gov (United States)

    Hens, K.; Tatum Ernest, C.; Novelli, A.; Paasonen, P.; Sipilä, M.; Petäjä, T.; Nölscher, A.; Taraborrelli, D.; Keronen, P.; Trawny, K.; Kubistin, D.; Oswald, R.; Axinte, R.; Hosaynali Beygi, Z.; Auld, J.; Klüpfel, T.; Mesarchaki, E.; Song, W.; Valverde Canossa, J.; González Orozco, D.; Königstedt, R.; Bohn, B.; Rudolf, M.; Fischer, H.; Williams, J.; Crowley, J.; Martinez, M.; Harder, H. D.; Lelieveld, J.

    2012-12-01

    Forests cover about one third of the earth's total land surface and are known to be an important global source of biogenic volatile organic compounds (BVOCs) that are partly very reactive towards OH. Different types of forests are known to emit various characteristic BVOCs significantly influencing atmospheric oxidation chemistry. Measurements of OH and HO2 radicals in forest environments, however, reveal a serious lack of understanding of the underlying processes. The HUMPPA-COPEC intensive field campaign took place in summer 2010 at the SMEAR II station, located in Hyytiälä, Southern Finland, as collaboration between the Max Planck Institute for Chemistry and the University of Helsinki. The main goal of the campaign was to investigate the summertime emissions and photochemistry in a boreal forest. Comprehensive measurements including observations of many VOCs, HOx, and total OH reactivity were conducted to increase our understanding of atmospheric self-cleaning processes based on detailed analysis of production and loss mechanisms of the hydroxyl radical. Also the HOx budget in a coniferous forest was examined by using direct calculations from measured species as well as an observationally constrained chemical box model in steady state. For HUMPPA-COPEC chemical reaction schemes considering isoprene as the predominant primary BVOC lead to an over prediction of the measured OH concentration by a factor of up to 4. However, only a minor fraction of the measured total OH reactivity can be explained by measured isoprene. A preliminary terpene mechanism, taking the most abundant terpenes measured during HUMPPA-COPEC-2010 and their oxidation products into account, improves the agreement between simulated and measured OH, but is not sufficient to explain the missing OH reactivity in all cases. HO2 is described reasonably well by the model for conditions where the modeled and measured total OH reactivity agree. For lower than measured reactivity, the HO2 mixing ratios

  15. Dissolved Organic Carbon in Boreal Black Spruce Forest: Sources, Chemistry, and Biodegradability

    Science.gov (United States)

    Wickland, K. P.; Neff, J. C.; Aiken, G. R.

    2006-12-01

    Northern terrestrial ecosystems are commonly characterized by large stores of soil organic matter and are a major source of dissolved organic carbon (DOC) to aquatic systems. Recent changes in climate may be impacting the fate of terrestrial DOC in these high latitude ecosystems. Terrestrially-derived DOC can be metabolized by microbes in soils, sorbed to mineral soils, or transported to ground or surface waters. To understand what determines the fate of terrestrial DOC in northern ecosystems, it is essential to quantify the chemical nature and potential biodegradability of this DOC, and to know how factors such as vegetation and hydrology influence these qualities. We examined the chemistry and potential biodegradability of DOC from black spruce forest, a dominant ecosystem type in the boreal regions of Alaska and Canada. Over the course of one year, soil pore waters were collected from three black spruce sites that spanned a range of hydrologic regimes and permafrost extents, designated as well drained (WD), moderately well drained (MD), and poorly drained (PD), and from thermokarst wetlands (TW) that had formed within the PD site due to permafrost melting. DOC chemistry was characterized using XAD resin fractionation, UV-Vis absorbance, and DOC fluorescence measurements. Potential biodegradability was assessed by incubating the samples for one month, and measuring CO2 production over time. We also measured chemistry and potential biodegradability of DOC leached from dominant vegetation species. Soil pore water DOC from all sites was dominated by hydrophobic acids and was highly aromatic, while the chemical composition of vegetation leachate DOC varied with species. There was no seasonal variability in soil pore water DOC chemistry or biodegradability; however DOC collected from PD was less biodegradable than DOC from the other sites (6% loss vs. 13-15% loss). The potential biodegradability of vegetation-derived DOC ranged from 10%-90% loss, and was strongly

  16. Composition and temporal behavior of ambient ions in the boreal forest

    OpenAIRE

    Ehn, M.; Junninen, H.; T. Petäjä; Kurtén, T.; Kerminen, V.-M.; S. Schobesberger; Manninen, H.E.; I. K. Ortega; Vehkamäki, H.; Kulmala, M.; Worsnop, D. R.

    2010-01-01

    A recently developed atmospheric pressure interface mass spectrometer (APi-TOF) measured the negative and positive ambient ion composition at a boreal forest site. As observed in previous studies, the negative ions were dominated by strong organic and inorganic acids (e.g. malonic, nitric and sulfuric acid), whereas the positive ions consisted of strong bases (e.g. alkyl pyridines and quinolines). Several new ions and clusters of ions were identified based on their exact masses, made possible...

  17. Ammonia and nitric acid emissions from wetlands and boreal forest fires

    International Nuclear Information System (INIS)

    NASA has developed a sensing technique involving collection of gases on a metal oxide denuder surface that is capable of simultaneous, sensitive measurements of HNO3 and NH3. This chapter presents the results of a study of the applicability of the denuder technique for measurements of HNO3 and NH3 in a smoke plume during biomass burning and discusses measurements made during three prescribed fires in temperature wetlands and boreal ecosystems

  18. Multi-trophic resilience of boreal lake ecosystems to forest fires

    Science.gov (United States)

    Lewis, Tyler L.; Lindberg, Mark S.; Schmutz, Joel A.; Bertram, M.R.

    2014-01-01

    Fires are the major natural disturbance in the boreal forest, and their frequency and intensity will likely increase as the climate warms. Terrestrial nutrients released by fires may be transported to boreal lakes, stimulating increased primary productivity, which may radiate through multiple trophic levels. Using a before-after-control-impact (BACI) design, with pre- and postfire data from burned and unburned areas, we examined effects of a natural fire across several trophic levels of boreal lakes, from nutrient and chlorophyll levels, to macroinvertebrates, to waterbirds. Concentrations of total nitrogen and phosphorus were not affected by the fire. Chlorophyll levels were also unaffected, likely reflecting the stable nutrient concentrations. For aquatic invertebrates, we found that densities of three functional feeding groups did not respond to the fire (filterers, gatherers, scrapers), while two groups increased (shredders, predators). Amphipods accounted for 98% of shredder numbers, and we hypothesize that fire-mediated habitat changes may have favored their generalist feeding and habitat ecology. This increase in amphipods may, in turn, have driven increased predator densities, as amphipods were the most numerous invertebrate in our lakes and are commonly taken as prey. Finally, abundance of waterbird young, which feed primarily on aquatic invertebrates, was not affected by the fire. Overall, ecosystems of our study lakes were largely resilient to forest fires, likely due to their high initial nutrient concentrations and small catchment sizes. Moreover, this resilience spanned multiple trophic levels, a significant result for ecologically similar boreal regions, especially given the high potential for increased fires with future climate change.

  19. Moose population density and habitat productivity as drivers of ecosystem processes in northern boreal forests

    OpenAIRE

    Persson, Inga-Lill

    2003-01-01

    Ungulates have traditionally been viewed as consumers of plants and prey for predators, but recent studies have revealed that they also can have a significant indirect impact on fundamental ecosystem processes and biodiversity. In my thesis, I focus on how moose (Alces alces) can affect the boreal forests ecosystem in Sweden. Because of its wide distribution and at present high population densities we can expect moose to be important. The outcome depends on moose density as well as habitat pr...

  20. Biotic stress accelerates formation of climate-relevant aerosols in boreal forests

    Directory of Open Access Journals (Sweden)

    J. Joutsensaari

    2015-04-01

    Full Text Available Boreal forests are a major source of climate-relevant biogenic secondary organic aerosols (SOA and will be greatly influenced by increasing temperature. Global warming is predicted to increase emissions of reactive biogenic volatile organic compounds (BVOC from vegetation directly, but will also induce large-scale insect outbreaks, which significantly increase emissions of reactive BVOC. Thus, climate change factors could substantially accelerate the formation of biogenic SOA in the troposphere. In this study, we have combined results from field and laboratory experiments, satellite observations and global scale modelling in order to evaluate the effects of insect herbivory and large-scale outbreaks on SOA formation and the Earth's climate. Field measurements demonstrated 11-fold and 20-fold increases in monoterpene and sesquiterpene emissions, respectively, from damaged trees during a pine sawfly (Neodiprion sertifer outbreak in eastern Finland. Laboratory chamber experiments showed that feeding by pine weevils (Hylobius abietis increased VOC emissions from Scots pine and Norway spruce seedlings by 10–50 fold resulting in 200–1000 fold increases in SOA masses formed via ozonolysis. The influence of insect damage on aerosol concentrations in boreal forests was studied with a global chemical transport model GLOMAP and MODIS satellite observations. Global scale modelling was performed using a 10-fold increase in monoterpene emission rates and assuming 10% of the boreal forest area was experiencing outbreak. Results showed a clear increase in total particulate mass (local max. 480% and cloud condensation nuclei concentrations (45%. Satellite observations indicated a two-fold increase in aerosol optical depth (AOD over western Canada's pine forests in August during a bark beetle outbreak. These results suggest that more frequent insect outbreaks in a warming climate could result in substantial increase in biogenic SOA formation in the boreal

  1. Diverse growth trends and climate responses across Eurasia’s boreal forest

    Science.gov (United States)

    Hellmann, Lena; Agafonov, Leonid; Charpentier Ljungqvist, Fredrik; Churakova (Sidorova, Olga; Düthorn, Elisabeth; Esper, Jan; Hülsmann, Lisa; Kirdyanov, Alexander V.; Moiseev, Pavel; Myglan, Vladimir S.; Nikolaev, Anatoly N.; Reinig, Frederick; Schweingruber, Fritz H.; Solomina, Olga; Tegel, Willy; Büntgen, Ulf

    2016-07-01

    The area covered by boreal forests accounts for ∼16% of the global and 22% of the Northern Hemisphere landmass. Changes in the productivity and functioning of this circumpolar biome not only have strong effects on species composition and diversity at regional to larger scales, but also on the Earth’s carbon cycle. Although temporal inconsistency in the response of tree growth to temperature has been reported from some locations at the higher northern latitudes, a systematic dendroecological network assessment is still missing for most of the boreal zone. Here, we analyze the geographical patterns of changes in summer temperature and precipitation across northern Eurasia >60 °N since 1951 AD, as well as the growth trends and climate responses of 445 Pinus, Larix and Picea ring width chronologies in the same area and period. In contrast to widespread summer warming, fluctuations in precipitation and tree growth are spatially more diverse and overall less distinct. Although the influence of summer temperature on ring formation is increasing with latitude and distinct moisture effects are restricted to a few southern locations, growth sensitivity to June–July temperature variability is only significant at 16.6% of all sites (p ≤ 0.01). By revealing complex climate constraints on the productivity of Eurasia’s northern forests, our results question the a priori suitability of boreal tree-ring width chronologies for reconstructing summer temperatures. This study further emphasizes regional climate differences and their role on the dynamics of boreal ecosystems, and also underlines the importance of free data access to facilitate the compilation and evaluation of massively replicated and updated dendroecological networks.

  2. Source characterization of Highly Oxidized Multifunctional Compounds in a Boreal Forest Environment using Positive Matrix Factorization

    OpenAIRE

    Yan, Chao; Nie, Wei; Äijälä, Mikko; Rissanen, Matti P.; Canagaratna, Manjula R.; Massoli, Paola; Junninen, Heikki; Jokinen, Tuija; Sarnela, Nina; Häme, Silja; Schobesberger, Siegfried; Canonaco, Francesco; Prevot, Andre S. H.; Petäjä, Tuukka; Kulmala, Markku

    2016-01-01

    Highly oxidized multifunctional compounds (HOMs) have been demonstrated to be important for atmospheric secondary organic aerosols (SOA) and new particle formation (NPF), yet it remains unclear which the main atmospheric HOM formation pathways are. In this study, a nitrate ion based Chemical Ionization Atmospheric-Pressure-interface Time-of-flight mass spectrometer (CI-APi-TOF) was deployed to measure HOMs in the boreal forest in Hyytiälä, southern Finland. Positive matrix factorization (PMF)...

  3. A Simulation Model of Environmental Processes and Vegetation Patterns in Boreal Forests: Test Case Fairbanks, Alaska

    OpenAIRE

    Bonan, G. B.

    1988-01-01

    In this study, a simulation model of environmental processes in upland boreal forests was combined with a gap model of species-specific demographic responses to these processes. Required parameters consisted of easily obtainable climatic, soils, and species parameters. The model successfully reproduced seasonal patterns of solar radiation, soil moisture, and depths of freeze and thaw for different topographies at Fairbanks, Alaska. The model also adequately simulated stand structure and veget...

  4. A GIS-based landscape analysis of dissolved organic carbon in boreal headwater streams

    OpenAIRE

    Andersson, Jan-Olov

    2009-01-01

    In boreal catchments, stream water chemistry is influenced and controlled by several landscape factors. The influence of spatially distributed variables is in turn dependent on the hydrological scale. Headwater streams have larger variability of water chemistry, and thus together represent a large biodiversity, and therefore need to be monitored in official environmental assessments. One objective of this study was, using Geographical Information Systems (GIS), to analyse co-variation between...

  5. Relationships among fires, fungi, and soil dynamics in Alaskan Boreal Forests

    OpenAIRE

    Treseder, Kathleen K.; Mack, M. C.; Cross, A

    2004-01-01

    Fires are critical pathways of carbon loss from boreal forest soils, whereas microbial communities form equally critical controls over carbon accumulation between fires. We used a chronosequence in Alaska to test Read's hypothesis that arbuscular mycorrhizal fungi should dominate ecosystems with low accumulation of surface litter, and ectomycorrhizal fungi should proliferate where organic horizons are well-developed. This pattern is expected because ectomycorrhizal fungi display a greater cap...

  6. Remote sensing of snow-cover for the boreal forest zone using microwave rada

    OpenAIRE

    Luojus, Kari

    2009-01-01

    This doctoral dissertation describes the development of an operationally feasible snow monitoring methodology utilizing spaceborne synthetic aperture radar (SAR) imagery, intended for hydrological applications on the boreal forest zone. The snow-covered area (SCA) estimation methodology developed is characterized using extensive satellite-based datasets, including SAR-based estimation and optical reference data gathered during the snow-melt seasons of 1997-1998, 2000-2002 and 2004-2006 from n...

  7. Sustainable Development of the Boreal Forest: Interaction of Ecological, Social, and Business Feedbacks

    OpenAIRE

    Gail Whiteman; Stuart Chapin, F.

    1998-01-01

    Humans are an integral component of ecosystems, just as the products of ecosystems are critical to social systems. To understand the future state of the boreal forest, we must understand the ecological, social, economic, and business interactions that link ecological and social systems into a common regional system, as well as the feedbacks that govern changes in these interactions. We analyze the negative feedbacks that promoted a sustainable interaction between ecological and social systems...

  8. Massive mortality of aspen following severe drought along the southern edge of the Canadian boreal forest

    OpenAIRE

    Michaelian, Michael; Hogg, Edward H.; Hall, Ronald J.; Arsenault, Eric

    2011-01-01

    Drought-induced, regional-scale dieback of forests has emerged as a global concern that is expected to escalate under model projections of climate change. Since 2000, drought of unusual severity, extent, and duration has affected large areas of western North America, leading to regional-scale dieback of forests in the southwestern US. We report on drought impacts on forests in a region farther north, encompassing the transition between boreal forest and prairie in western Canada. A central qu...

  9. Short-term controls on the age of microbial carbon sources in boreal forest soils

    OpenAIRE

    Czimczik, C; Trumbore, S

    2007-01-01

    [1] One predicted positive feedback of increasing temperatures in the boreal region is carbon (C) loss through enhanced microbial decomposition of soil organic matter (SOM). The degree to which temperature sensitivity for decomposition varies across a range of C-substrates remains uncertain. Using incubations, we tested whether microorganisms shift to more recalcitrant substrates (with longer turnover times) at higher temperatures at low or increased soil moisture. We measured the radiocarbon...

  10. Biotic stress accelerates formation of climate-relevant aerosols in boreal forests

    Science.gov (United States)

    Joutsensaari, J.; Yli-Pirilä, P.; Korhonen, H.; Arola, A.; Blande, J. D.; Heijari, J.; Kivimäenpää, M.; Mikkonen, S.; Hao, L.; Miettinen, P.; Lyytikäinen-Saarenmaa, P.; Faiola, C. L.; Laaksonen, A.; Holopainen, J. K.

    2015-11-01

    Boreal forests are a major source of climate-relevant biogenic secondary organic aerosols (SOAs) and will be greatly influenced by increasing temperature. Global warming is predicted to not only increase emissions of reactive biogenic volatile organic compounds (BVOCs) from vegetation directly but also induce large-scale insect outbreaks, which significantly increase emissions of reactive BVOCs. Thus, climate change factors could substantially accelerate the formation of biogenic SOAs in the troposphere. In this study, we have combined results from field and laboratory experiments, satellite observations and global-scale modelling in order to evaluate the effects of insect herbivory and large-scale outbreaks on SOA formation and the Earth's climate. Field measurements demonstrated 11-fold and 20-fold increases in monoterpene and sesquiterpene emissions respectively from damaged trees during a pine sawfly (Neodiprion sertifer) outbreak in eastern Finland. Laboratory chamber experiments showed that feeding by pine weevils (Hylobius abietis) increased VOC emissions from Scots pine and Norway spruce seedlings by 10-50 fold, resulting in 200-1000-fold increases in SOA masses formed via ozonolysis. The influence of insect damage on aerosol concentrations in boreal forests was studied with a global chemical transport model GLOMAP and MODIS satellite observations. Global-scale modelling was performed using a 10-fold increase in monoterpene emission rates and assuming 10 % of the boreal forest area was experiencing outbreak. Results showed a clear increase in total particulate mass (local max. 480 %) and cloud condensation nuclei concentrations (45 %). Satellite observations indicated a 2-fold increase in aerosol optical depth over western Canada's pine forests in August during a bark beetle outbreak. These results suggest that more frequent insect outbreaks in a warming climate could result in substantial increase in biogenic SOA formation in the boreal zone and, thus

  11. Influence of glacial landform hydrology on phosphorus budgets of shallow lakes on the Boreal Plain, Canada

    Science.gov (United States)

    Plach, Janina M.; Ferone, Jenny-Marie; Gibbons, Zabrina; Smerdon, Brian D.; Mertens, Alexander; Mendoza, Carl A.; Petrone, Richard M.; Devito, Kevin J.

    2016-04-01

    A comparative study of three shallow lake catchments in contrasting glacial landscapes (coarse-textured outwash, fine-textured-till hummocky moraines and glacio-lacustrine clay-till plains) demonstrated a distinct landform control on the proportion and type of surface and groundwater sources influencing total phosphorus ([P]) and total dissolved phosphorus ([DP]) concentrations, and P budgets of lakes on the Boreal Plain of the Western Boreal Forest, Alberta, Canada. Lakes located on fine-textured landforms had high [P] and [DP] (median 148 and 148 μg L-1 glacio-lacustrine plains; 99 and 63 μg L-1 moraine, respectively) linked to shallow groundwater loadings from near-surface peat with high [P] from adjacent wetlands. In contrast, the lowest lake [P] and [DP] (median 50 and 11 μg L-1, respectively) occurred on the coarse-textured landform, reflecting greater inputs of deep mineral-groundwater with low [P] from quartz-rich substrates. Annual lake P budgets reflected lake connectivity to the surrounding landform and relative contributions of P by surface versus groundwater. They also reflected distinct scales of groundwater (larger-scale versus short, shallow-flow paths) with differing [P] between landform types and occurrence of internal biogeochemical P cycling within landforms. A regional lake survey reflected trends from the catchment-scale, linking landform type to potential P sources as well as topographic position to potential trophic status across the Boreal Plain. Together, the results provide a conceptual framework for the scale of interactions between lakes and surrounding source waters influencing P loadings in differing hydrogeological landscapes, important to management strategies and predicting impacts of land-use disturbances on productivity of Boreal Plain lakes.

  12. Carbon-sequestration and ecosystem services in the boreal ecoregion of Alaska

    Science.gov (United States)

    Wang, B.; Manies, K.; Labay, K.; Johnson, W. N.; Harden, J. W.

    2011-12-01

    Managing public lands for carbon (C) sequestration is increasingly discussed as a component of national carbon policies. However, management of public land to facilitate carbon sequestration must be considered in the context of other management mandates and the effects on other ecosystem services. Of the United States Fish and Wildlife Service's (USFWS) National Wildlife Refuge lands in Alaska, about 35% are in the boreal ecoregion; primarily in the Intermountain and the Alaska Range Transition ecoregions. These refuges were established to conserve wildlife habitat, fulfill treaty obligations, provide for continued subsistence uses, and ensure necessary water quality and quantity. One of the major factors in determining ecosystem distribution in the boreal ecoregion is disturbance. Fire is the dominant disturbance for Alaska's boreal region. Most USFWS refuge lands are managed with "limited" suppression, where fires burn naturally and are monitored to assure the protection of human life, property, and site specific values (such as historical or religious). However, there is increasing interest in biomass harvest and combustion for local energy production. Harvest and fire can have differing effects on both the spatial and temporal aspects of carbon storage. The current biomass harvest for energy production proposals are considered to be C neutral because they focus on "hazardous" biomass which would burn naturally or in a prescribed burn. The goal of this effort is to explore the relation between C storage and other public land management priorities, as well as, to explore how disturbance type (fire and harvest) affect C storage and boreal ecosystem distribution in the context of wildlife habitat and subsistence use management priorities. We present a conceptual model that defines the linkages among these management priorities, a data gap analysis, and scenarios to be evaluated.

  13. Combining MODIS and Landsat imagery to estimate and map boreal forest cover loss

    Science.gov (United States)

    Potapov, P.; Hansen, M.C.; Stehman, S.V.; Loveland, T.R.; Pittman, K.

    2008-01-01

    Estimation of forest cover change is important for boreal forests, one of the most extensive forested biomes, due to its unique role in global timber stock, carbon sequestration and deposition, and high vulnerability to the effects of global climate change. We used time-series data from the MODerate Resolution Imaging Spectroradiometer (MODIS) to produce annual forest cover loss hotspot maps. These maps were used to assign all blocks (18.5 by 18.5??km) partitioning the boreal biome into strata of high, medium and low likelihood of forest cover loss. A stratified random sample of 118 blocks was interpreted for forest cover and forest cover loss using high spatial resolution Landsat imagery from 2000 and 2005. Area of forest cover gross loss from 2000 to 2005 within the boreal biome is estimated to be 1.63% (standard error 0.10%) of the total biome area, and represents a 4.02% reduction in year 2000 forest cover. The proportion of identified forest cover loss relative to regional forest area is much higher in North America than in Eurasia (5.63% to 3.00%). Of the total forest cover loss identified, 58.9% is attributable to wildfires. The MODIS pan-boreal change hotspot estimates reveal significant increases in forest cover loss due to wildfires in 2002 and 2003, with 2003 being the peak year of loss within the 5-year study period. Overall, the precision of the aggregate forest cover loss estimates derived from the Landsat data and the value of the MODIS-derived map displaying the spatial and temporal patterns of forest loss demonstrate the efficacy of this protocol for operational, cost-effective, and timely biome-wide monitoring of gross forest cover loss. ?? 2008 Elsevier Inc.

  14. Revealing sources of biological methane production in boreal upland forests (metafor): forest floor flux

    Czech Academy of Sciences Publication Activity Database

    Halmeenmäki, E.; Macháčová, Kateřina; Santalahti, M.; Fritze, H.; Heinonsalo, J.; Pihlatie, M.

    Helsinky : Finnish association for aerosol research FAAR, 2014 - (Kulmala, M.; Lintunen, A.; Kontkanen, J.), s. 270-272 ISBN 978-952-7091-01-2. ISSN 0784-3496. - (Report series in aerosol science. 157). [International Aerosol Conference 2014. Busan (KR), 28.08.2014-02.09.2014] Institutional support: RVO:67179843 Keywords : methane * boreal upland forest * forest floor emission * flux Subject RIV: EH - Ecology, Behaviour

  15. Landscape control of uranium and thorium in boreal streams : spatiotemporal variability and the role of wetlands

    OpenAIRE

    F. Lidman; C. M. Mörth; H. Laudon

    2012-01-01

    The concentrations of uranium and thorium in ten partly nested streams in the boreal forest region were monitored over a two-year period. The investigated catchments ranged from small headwaters (0.1 km2) up to a fourth-order stream (67 km2). Considerable spatiotemporal variations were observed, with little or no correlation between streams. The fluxes of both uranium and thorium varied substantially between the subcatchments, ranging from 1.7 to ...

  16. Principal results of Boreal - Tethyan correlation of the Jurassic – Cretaceous boundary by magnetostratigraphy

    Czech Academy of Sciences Publication Activity Database

    Houša, Václav; Pruner, Petr; Zakharov, V.; Košťák, M.; Chadima, Martin; Rogov, M.; Šlechta, Stanislav; Mazuch, M.

    Tunis : Faculty of Sciences of Bizerte ; Faculty of Sciences of Tunis ; Tunisian Association of Natural Sciences, 2008 - (Boughdiri, M.; Soussi, M.). s. 81-82 [International Symposium of IGCP 506 /5./. 28.03.2008-31.03.2008, Hammamet] R&D Projects: GA ČR GA205/07/1365 Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetostratigraphy * Boreal-Tethyan correlation * Jurassic * Cretaceous boundary Subject RIV: DB - Geology ; Mineralogy

  17. Long-Range and Deep Convective Transport of Boreal Forest Fire Emissions

    OpenAIRE

    Damoah, Richard

    2006-01-01

    Boreal forest fire emissions have strong impact on the concentrations of atmospheric trace gases and aerosols on local, regional and even continental scales. This dissertation investigates the impact of long-range transport of forest fire emissions on the atmosphere. It uses Satellite and lidar measurements with Lagrangian particle dispersion model FLEXPART to understand the transport processes. The satellite data provided a unique opportunity for validating the model simulations of troposphe...

  18. ACE-FTS observations of pyrogenic trace species in boreal biomass burning plumes during BORTAS

    Directory of Open Access Journals (Sweden)

    K. A. Tereszchuk

    2012-12-01

    Full Text Available To further our understanding of the effects of biomass burning emissions on atmospheric composition, the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS campaign was conducted on 12 July to 3 August 2011 during the Boreal forest fire season in Canada. The simultaneous aerial, ground and satellite measurement campaign sought to record instances of Boreal biomass burning to measure the tropospheric volume mixing ratios (VMRs of short- and long-lived trace molecular species from biomass burning emissions. The goal was to investigate the connection between the composition and the distribution of these pyrogenic outflows and their resulting perturbation to atmospheric chemistry, with particular focus on oxidant species to determine the overall impact on the oxidizing capacity of the free troposphere.

    Measurements of pyrogenic trace species in Boreal biomass burning plumes were made by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS onboard the Canadian Space Agency (CSA SCISAT-1 satellite during the BORTAS campaign. Even though most biomass burning smoke is typically confined to the boundary layer, emissions are often injected directly into the upper troposphere via fire-related convective processes, thus allowing space-borne instruments to measure these pyrogenic outflows. An extensive set of 15 molecules, CH3OH, CH4, C2H2, C2H6, C3H6O, CO, HCN, HCOOH, HNO3, H2CO, NO, NO2, OCS, O3 and PAN have been analyzed. Included in this analysis is the calculation of age-dependent sets of enhancement ratios for each of the species.

  19. Earlier springs decrease peak summer productivity in North American boreal forests

    International Nuclear Information System (INIS)

    In the northern high latitudes, alternative hypotheses with regards to how warming-related shifts in seasonality influence ecosystem productivity exist. Increased plant growth associated with a longer growing season may enhance ecosystem productivity, but shifts to earlier springs may also negatively influence soil moisture status and productivity during the peak of the growing season. Here, we analyzed nearly three decades (1982–2008) of observational records and derived products, including satellite microwave and optical imagery as well as upscaled ecosystem flux observations, to better understand how shifts in seasonality impact hydrology and productivity in the North American boreal forests. We identified a dominant adverse influence of earlier springs on peak summer forest greenness, actual evapotranspiration and productivity at interannual time scales across the drier western and central sections of the North American boreal forests. In the vast regions where this spring onset mechanism operates, ecosystem productivity gains from earlier springs during the early portion of the growing season are effectively cancelled through corresponding losses in the later portion. Our results also indicate that recent decadal shifts towards earlier springs and associated drying in the midst of the growing season over western North American boreal forests may have contributed to the reported declines in summer productivity and increases in tree mortality and fire activity. With projections of accelerated northern high-latitude warming and associated shifts to earlier springs, persistent soil moisture deficits in peak summer may be an effective mechanism for regional-scale boreal forest dieback through their strong influence on productivity, tree mortality and disturbance dynamics. (letter)

  20. Habitat requirements of juvenile salmonids:towards ecologically-based fisheries management in boreal streams

    OpenAIRE

    Mäki-Petäys, A. (Aki)

    1999-01-01

    Abstract For effective management of stream salmonids, it is essential to (i) assess the productive potential of a stream in relation to species-specific habitat requirements, and to (ii) identify the key factors underlying any bottleneck periods during the life cycle of a fish. For this purpose, this PhD-thesis focuses on the mechanisms of habitat selection by juvenile salmonids in boreal streams. Habitat preference curves for depth, water velocity, substrate and instream cover for br...

  1. Linking landscape characteristics, streamwater acidity and brown trout (Salmo trutta) distributions in a boreal stream network

    OpenAIRE

    Buffam, Ishi

    2007-01-01

    Perturbations of stream ecosystems are often mediated by the terrestrial watershed, making the understanding of linkages between watersheds and streams essential. In this thesis I explore the connections between landscape characteristics, streamwater acidity and brown trout (Salmo trutta) distributions in Krycklan, a 67 km2 boreal stream network in northern Sweden. The study focuses on hydrochemical changes during the snowmelt-driven spring flood, a period of episodic acidity which is thought...

  2. Influence of airborne chemical substances on the behaviour of radionuclides in boreal forest ecosystems

    International Nuclear Information System (INIS)

    Atmospheric deposition of chemical substances may influence the behaviour of radionuclides in soil and their uptake in plants. This is a fact that has so far received limited attention in radioecological studies. This paper presents briefly two cases where differences in atmospheric deposition of heavy metals from a strong pollution source and marine aerosols, respectively, influence the turnover of radionuclides in natural boreal ecosystems. (au)

  3. Disturbance in boreal spruce forest - immediate dynamics from stand to understorey level

    OpenAIRE

    Hautala, Harri

    2008-01-01

    The immediate effects of two human-related vegetation disturbances, (1) green tree retention (GTR) patch felling and scarification by harrowing and (2) experimental understorey vegetation layer removal, were examined in boreal forest stands in Finland. Effects of GTR patch felling and scarification on tree uprootings, on coarse woody debris (CWD) and on epixylic plant community were followed in upland and in paludified forest types. Uprootings increased considerably during 2-3 years afte...

  4. Controls on snowmelt water mean transit times in northern boreal catchments

    OpenAIRE

    Lyon, S. W.; H. Laudon; Seibert, Jan; Morth, M.; D. Tetzlaff; K. H. Bishop

    2010-01-01

    Catchment-scale transit times for water are increasingly being recognized as an important control on geochemical processes. In this study, snowmelt water mean transit times (MTTs) were estimated for the 15 Krycklan research catchments in northern boreal Sweden. The snowmelt water MTTs were assumed to be representative of the catchment-scale hydrologic response during the spring thaw period and, as such, may be considered to be a component of the catchment's overall MTT. These snowmelt water M...

  5. Effects of weather on survival in populations of boreal toads in Colorado

    Science.gov (United States)

    Scherer, R. D.; Muths, E.; Lambert, B.A.

    2008-01-01

    Understanding the relationships between animal population demography and the abiotic and biotic elements of the environments in which they live is a central objective in population ecology. For example, correlations between weather variables and the probability of survival in populations of temperate zone amphibians may be broadly applicable to several species if such correlations can be validated for multiple situations. This study focuses on the probability of survival and evaluates hypotheses based on six weather variables in three populations of Boreal Toads (Bufo boreas) from central Colorado over eight years. In addition to suggesting a relationship between some weather variables and survival probability in Boreal Toad populations, this study uses robust methods and highlights the need for demographic estimates that are precise and have minimal bias. Capture-recapture methods were used to collect the data, and the Cormack-Jolly-Seber model in program MARK was used for analysis. The top models included minimum daily winter air temperature, and the sum of the model weights for these models was 0.956. Weaker support was found for the importance of snow depth and the amount of environmental moisture in winter in modeling survival probability. Minimum daily winter air temperature was positively correlated with the probability of survival in Boreal Toads at other sites in Colorado and has been identified as an important covariate in studies in other parts of the world. If air temperatures are an important component of survival for Boreal Toads or other amphibians, changes in climate may have profound impacts on populations. Copyright 2008 Society for the Study of Amphibians and Reptiles.

  6. Vulnerability to climate-induced changes in ecosystem services of boreal forests

    Science.gov (United States)

    Holmberg, Maria; Rankinen, Katri; Aalto, Tuula; Akujärvi, Anu; Nadir Arslan, Ali; Liski, Jari; Markkanen, Tiina; Mäkelä, Annikki; Peltoniemi, Mikko

    2016-04-01

    Boreal forests provide an array of ecosystem services. They regulate climate, and carbon, water and nutrient fluxes, and provide renewable raw material, food, and recreational possibilities. Rapid climate warming is projected for the boreal zone, and has already been observed in Finland, which sets these services at risk. MONIMET (LIFE12 ENV/FI/000409, 2.9.2013 - 1.9.2017) is a project funded by EU Life programme about Climate Change Indicators and Vulnerability of Boreal Zone Applying Innovative Observation and Modeling Techniques. The coordinating beneficiary of the project is the Finnish Meteorological Institute. Associated beneficiaries are the Natural Resources Institute Finland, the Finnish Environment Institute and the University of Helsinki. In the MONIMET project, we use state-of-the-art models and new monitoring methods to investigate the impacts of a warming climate on the provision of ecosystem services of boreal forests. This poster presents results on carbon storage in soil and assessment of drought indices, as a preparation for assessing the vulnerability of society to climate-induced changes in ecosystem services. The risk of decreasing provision of ecosystem services depends on the sensitivity of the ecosystem as well as its exposure to climate stress. The vulnerability of society, in turn, depends on the risk of decreasing provision of a certain service in combination with society's demand for that service. In the next phase, we will look for solutions to challenges relating to the quantification of the demand for ecosystem services and differences in spatial extent and resolution of the information on future supply and demand.

  7. Response of water use efficiency to summer drought in boreal Scots pine forests in Finland

    OpenAIRE

    Gao, Yao; Markkanen, Tiina; Aurela, Mika; Mammarella, Ivan; Thum, Tea; Tsuruta, Aki; YANG, HUIYI; Aalto, Tuula

    2016-01-01

    The influence of drought on plant functioning has received considerable attention in recent years, although our understanding of the response of carbon and water coupling in terrestrial ecosystems remains unclear. In this study, we investigated the response of water use efficiency to summer drought in boreal forests at daily time scales mainly using eddy covariance flux data. In addition, simulation results from the JSBACH land surface model were evaluated against the observed results. ...

  8. Boreal winter comparison of auroral images from Polar UVI and IMAGE FUV

    Science.gov (United States)

    Spann, J. F.; Germany, G.; Maddox, W.; Fillingim, M.; Parks, G.; Mende, S.

    2004-12-01

    Same-scene images made with Polar UVI and IMAGE FUV are compared for the boreal winter of 2000-2001. The results of the comparison are used to determine whether the use of both instruments could lead to a better evaluation of the average precipitation and total energy input than with either one individually. These results are a part of a broader investigation to quantitatively compare conjugate images using both instruments and to correlate observed asymmetries with solar wind and seasonal parameters.

  9. Pathways for Methanogenesis and Diversity of Methanogenic Archaea in Three Boreal Peatland Ecosystems

    OpenAIRE

    P. E. Galand; Fritze, H.; Conrad, R.; K. Yrjälä

    2005-01-01

    The main objectives of this study were to uncover the pathways used for methanogenesis in three different boreal peatland ecosystems and to describe the methanogenic populations involved. The mesotrophic fen had the lowest proportion of CH4 produced from H2-CO2. The oligotrophic fen was the most hydrogenotrophic, followed by the ombrotrophic bog. Each site was characterized by a specific group of methanogenic sequences belonging to Methanosaeta spp. (mesotrophic fen), rice cluster-I (oligotro...

  10. Regional Instability in the Abundance of Open Stands in the Boreal Forest of Eastern Canada

    OpenAIRE

    Rija Rapanoela; Frédéric Raulier; Sylvie Gauthier

    2016-01-01

    Fires are a key disturbance of boreal forests. In fact, they are the main source of renewal and evolution for forest stands. The variability of fire through space and time results in a diversified forest mosaic, altering their species composition, structure and productivity. A resilient forest is assumed to be in a state of dynamic equilibrium with the fire regime, so that the composition, age structure and succession stages of forests should be consistent with the fire regime. Dense spruce-m...

  11. Soil carbon stocks and their rates of accumulation and loss in a boreal forest landscape

    Science.gov (United States)

    Rapalee, G.; Trumbore, S.E.; Davidson, E.A.; Harden, J.W.; Veldhuis, H.

    1998-01-01

    Boreal forests and wetlands are thought to be significant carbon sinks, and they could become net C sources as the Earth warms. Most of the C of boreal forest ecosystems is stored in the moss layer and in the soil. The objective of this study was to estimate soil C stocks (including moss layers) and rates of accumulation and loss for a 733 km2 area of the BOReal Ecosystem-Atmosphere Study site in northern Manitoba, using data from smaller-scale intensive field studies. A simple process-based model developed from measurements of soil C inventories and radiocarbon was used to relate soil C storage and dynamics to soil drainage and forest stand age. Soil C stocks covary with soil drainage class, with the largest C stocks occurring in poorly drained sites. Estimated rates of soil C accumulation or loss are sensitive to the estimated decomposition constants for the large pool of deep soil C, and improved understanding of deep soil C decomposition is needed. While the upper moss layers regrow and accumulate C after fires, the deep C dynamics vary across the landscape, from a small net sink to a significant source. Estimated net soil C accumulation, averaged for the entire 733 km2 area, was 20 g C m-2 yr-1 (28 g C m-2 yr-1 accumulation in surface mosses offset by 8 g C m-2 yr-1 lost from deep C pools) in a year with no fire. Most of the C accumulated in poorly and very poorly drained soils (peatlands and wetlands). Burning of the moss layer in only 1% of uplands would offset the C stored in the remaining 99% of the area. Significant interannual variability in C storage is expected because of the irregular occurrence of fire in space and time. The effects of climate change and management on fire frequency and on decomposition of immense deep soil C stocks are key to understanding future C budgets in boreal forests.

  12. Maintaining animal assemblages through single-species management: the case of threatened caribou in boreal forest.

    Science.gov (United States)

    Bichet, Orphé; Dupuch, Angélique; Hébert, Christian; Le Borgne, Hélène Le; Fortin, Daniel

    2016-03-01

    With the intensification of human activities, preserving animal populations is a contemporary challenge of critical importance. In this context, the umbrella species concept is appealing because preserving a single species should result in the protection of multiple co-occurring species. Practitioners, though, face the task of having to find suitable umbrellas to develop single-species management guidelines. In North America, boreal forests must be managed to facilitate the recovery of the threatened boreal caribou (Rangifer tarandus). Yet, the effect of caribou conservation on co-occurring animal species remains poorly documented. We tested if boreal caribou can constitute an effective umbrella for boreal fauna. Birds, small mammals, and insects were sampled along gradients of post-harvest and post-fire forest succession. Predictive models of occupancy were developed from the responses of 95 species to characteristics of forest stands and their surroundings. We then assessed the similarity of species occupancy expected between simulated harvested landscapes and a 90 000-km2 uncut landscape. Managed landscapes were simulated based on three levels of disturbance, two timber-harvest rotation cycles, and dispersed or aggregated cut-blocks. We found that management guidelines that were more likely to maintain caribou populations should also better preserve animal assemblages. Relative to fragmentation or harvest cycle, we detected a stronger effect of habitat loss on species assemblages. Disturbing 22%, 35%, and 45% of the landscape should result, respectively, in 80%, 60%, and 40% probability for caribou populations to be sustainable; in turn, this should result in regional species assemblages with Jaccard similarity indices of 0.86, 0.79, and 0.74, respectively, relative to the uncut landscape. Our study thus demonstrates the value of single-species management for animal conservation. Our quantitative approach allows for the evaluation of management guidelines prior

  13. The microbial communities and potential greenhouse gas production in boreal acid sulphate, non-acid sulphate, and reedy sulphidic soils

    International Nuclear Information System (INIS)

    Acid sulphate (AS) soils along the Baltic coasts contain significant amounts of organic carbon and nitrogen in their subsoils. The abundance, composition, and activity of microbial communities throughout the AS soil profile were analysed. The data from a drained AS soil were compared with those from a drained non-AS soil and a pristine wetland soil from the same region. Moreover, the potential production of methane, carbon dioxide, and nitrous oxide from the soils was determined under laboratory conditions. Direct microscopic counting, glucose-induced respiration (GIR), whole cell hybridisation, and extended phospholipid fatty acid (PLFA) analysis confirmed the presence of abundant microbial communities in the topsoil and also in the deepest Cg2 horizon of the AS soil. The patterns of microbial counts, biomass and activity in the profile of the AS soil and partly also in the non-AS soil therefore differed from the general tendency of gradual decreases in soil profiles. High respiration in the deepest Cg2 horizon of the AS soil (5.66 μg C g− 1 h− 1, as compared to 2.71 μg C g− 1 h− 1 in a top Ap horizon) is unusual but reasonable given the large amount of organic carbon in this horizon. Nitrous oxide production peaked in the BCgc horizon of the AS and in the BC horizon of the non-AS soil, but the peak value was ten-fold higher in the AS soil than in the non-AS soil (82.3 vs. 8.6 ng N g− 1d− 1). The data suggest that boreal AS soils on the Baltic coast contain high microbial abundance and activity. This, together with the abundant carbon and total and mineral nitrogen in the deep layers of AS soils, may result in substantial gas production. Consequently, high GHG emissions could occur, for example, when the generally high water table is lowered because of arable farming. - Highlights: •Boreal acid sulphate soils contain large amounts of organic C and N in subsoils. •Microbial communities throughout the acid sulphate soil profile were analysed.

  14. Uncoupled organic matter burial and quality in boreal lake sediments over the Holocene

    Science.gov (United States)

    Chmiel, Hannah E.; Niggemann, Jutta; Kokic, Jovana; Ferland, Marie-Ève; Dittmar, Thorsten; Sobek, Sebastian

    2015-09-01

    Boreal lake sediments are important sites of organic carbon (OC) storage, which have accumulated substantial amounts of OC over the Holocene epoch; the temporal evolution and the strength of this Holocene carbon (C) sink is, however, not well constrained. In this study we investigated the temporal record of carbon mass accumulation rates (CMARs) and assessed qualitative changes of terrestrially derived OC in the sediment profiles of seven Swedish boreal lakes, in order to evaluate the variability of boreal lake sediments as a C sink over time. CMARs were resolved on a short-term (centennial) and long-term (i.e., over millennia of the Holocene) timescale, using radioactive lead (210Pb) and carbon (14C) isotope dating. Sources and degradation state of terrestrially derived OC were identified and characterized by molecular analyses of lignin phenols. We found that CMARs varied substantially on both short-term and long-term scales and that the variability was mostly attributed to sedimentation rates and uncoupled from the OC content in the sediment profiles. The lignin phenol analyses revealed that woody material from gymnosperms was a dominant and constant OC source to the sediments over the Holocene. Furthermore, lignin-based degradation indices, such as acid-to-aldehyde ratios, indicated that postdepositional degradation in the sediments was very limited on longer timescales, implying that terrestrial OC is stabilized in the sediments on a permanent basis.

  15. Growth decline linked to warming-induced water limitation in hemi-boreal forests.

    Directory of Open Access Journals (Sweden)

    Xiuchen Wu

    Full Text Available Hemi-boreal forests, which make up the transition from temperate deciduous forests to boreal forests in southern Siberia, have experienced significant warming without any accompanying increase in precipitation during the last 80 years. This climatic change could have a profound impact on tree growth and on the stability of forest ecosystems in this region, but at present evidence for these impacts is lacking. In this study, we report a recent dramatic decline in the growth of hemi-boreal forests, based on ring width measurements from three dominant tree-species (Pinus sylvestris, Larix sibirica and Larix gmelinii, sampled from eight sites in the region. We found that regional tree growth has become increasingly limited by low soil water content in the pre- and early-growing season (from October of the previous year to July of the current year over the past 80 years. A warming-induced reduction in soil water content has also increased the climate sensitivity of these three tree species. Beginning in the mid-1980s, a clear decline in growth is evident for both the pine forests and the larch forests, although there are increasing trends in the proxy of soil water use efficiencies. Our findings are consistent with those from other parts of the world and provide valuable insights into the regional carbon cycle and vegetation dynamics, and should be useful for devising adaptive forest management strategies.

  16. Pinus sylvestris as a missing source of nitrous oxide and methane in boreal forest

    Science.gov (United States)

    Machacova, Katerina; Bäck, Jaana; Vanhatalo, Anni; Halmeenmäki, Elisa; Kolari, Pasi; Mammarella, Ivan; Pumpanen, Jukka; Acosta, Manuel; Urban, Otmar; Pihlatie, Mari

    2016-03-01

    Boreal forests comprise 73% of the world’s coniferous forests. Based on forest floor measurements, they have been considered a significant natural sink of methane (CH4) and a natural source of nitrous oxide (N2O), both of which are important greenhouse gases. However, the role of trees, especially conifers, in ecosystem N2O and CH4 exchange is only poorly understood. We show for the first time that mature Scots pine (Pinus sylvestris L.) trees consistently emit N2O and CH4 from both stems and shoots. The shoot fluxes of N2O and CH4 exceeded the stem flux rates by 16 and 41 times, respectively. Moreover, higher stem N2O and CH4 fluxes were observed from wet than from dry areas of the forest. The N2O release from boreal pine forests may thus be underestimated and the uptake of CH4 may be overestimated when ecosystem flux calculations are based solely on forest floor measurements. The contribution of pine trees to the N2O and CH4 exchange of the boreal pine forest seems to increase considerably under high soil water content, thus highlighting the urgent need to include tree-emissions in greenhouse gas emission inventories.

  17. Vulnerability of groundwater resources to interaction with river water in a boreal catchment

    Directory of Open Access Journals (Sweden)

    A. Rautio

    2015-02-01

    Full Text Available A low altitude aerial infrared (AIR survey was conducted to identify hydraulic connections between aquifers and rivers, and to map spatial surface temperature patterns along boreal rivers. In addition, the stable isotopic compositions (δ18O, δD, dissolved silica (DSi concentrations and electrical conductivity of water in combination with AIR data were used as tracers to verify the observed groundwater discharge into the river system in a boreal catchment. The results of AIR surveys and hydrogeochemical studies performed in the boreal catchment are presented. Based on low temperature anomalies in the AIR survey, around 370 groundwater–surface water interaction sites were located along the main river channel and its tributaries (203 km altogether. On the basis of AIR survey, the longitudinal temperature patterns of the studied rivers differed noticeably. The stable isotopes and DSi composition revealed major differences between the studied rivers. The interaction locations identified in the proximity of 12 municipal water intake plants during the low-flow seasons should be considered as potential risk areas for water intake plants during flood periods (groundwater quality deterioration due to bank infiltration, and should be taken under consideration in river basin management under changing climatic situations.

  18. Growth decline linked to warming-induced water limitation in hemi-boreal forests.

    Science.gov (United States)

    Wu, Xiuchen; Liu, Hongyan; Guo, Dali; Anenkhonov, Oleg A; Badmaeva, Natalya K; Sandanov, Denis V

    2012-01-01

    Hemi-boreal forests, which make up the transition from temperate deciduous forests to boreal forests in southern Siberia, have experienced significant warming without any accompanying increase in precipitation during the last 80 years. This climatic change could have a profound impact on tree growth and on the stability of forest ecosystems in this region, but at present evidence for these impacts is lacking. In this study, we report a recent dramatic decline in the growth of hemi-boreal forests, based on ring width measurements from three dominant tree-species (Pinus sylvestris, Larix sibirica and Larix gmelinii), sampled from eight sites in the region. We found that regional tree growth has become increasingly limited by low soil water content in the pre- and early-growing season (from October of the previous year to July of the current year) over the past 80 years. A warming-induced reduction in soil water content has also increased the climate sensitivity of these three tree species. Beginning in the mid-1980s, a clear decline in growth is evident for both the pine forests and the larch forests, although there are increasing trends in the proxy of soil water use efficiencies. Our findings are consistent with those from other parts of the world and provide valuable insights into the regional carbon cycle and vegetation dynamics, and should be useful for devising adaptive forest management strategies. PMID:22916142

  19. An Analysis of Drought Indicators for Detecting Dry Spells over Boreal Forest

    Science.gov (United States)

    Gao, Y.; Markkanen, T.; Aalto, T.

    2014-12-01

    Regional-scale impacts of drought on forest growth also take place in high-latitude boreal region, as in low- and middle-latitudes. A variety of drought indicators have been developed in the past, in order to quantify the duration and intensity of drought. The aims of this study are: 1) to investigate the relationships between various drought indicators and forest CO2 exchange in boreal area; 2) to evaluate the drought indicators based on modeled results from JSBACH land surface model through comparing to the observation based drought indicators, aiming to reliable future drought prediction. The standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) are calculated from both observational and modeled climate variables over 30 years (1981-2010). The soil moisture index (SMI) is also processed using available 5-layer soil moisture in JSBACH modeled results. Those indicators are developed for multiple time scales to capture the beginning and ending points when the forest in this boreal area responds to certain drought episodes. The different responses from coniferous, deciduous and mixed forest types to drought will also be studied.

  20. The boreal summer intraseasonal oscillation simulated by four Chinese AGCMs participating in the CMIP5 project

    Science.gov (United States)

    Zhao, Chongbo; Zhou, Tianjun; Song, Lianchun; Ren, Hongli

    2014-09-01

    The performances of four Chinese AGCMs participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) in the simulation of the boreal summer intraseasonal oscillation (BSISO) are assessed. The authors focus on the major characteristics of BSISO: the intensity, significant period, and propagation. The results show that the four AGCMs can reproduce boreal summer intraseasonal signals of precipitation; however their limitations are also evident. Compared with the Climate Prediction Center Merged Analysis of Precipitation (CMAP) data, the models underestimate the strength of the intraseasonal oscillation (ISO) over the eastern equatorial Indian Ocean (IO) during the boreal summer (May to October), but overestimate the intraseasonal variability over the western Pacific (WP). In the model results, the westward propagation dominates, whereas the eastward propagation dominates in the CMAP data. The northward propagation in these models is tilted southwest-northeast, which is also different from the CMAP result. Thus, there is not a northeast-southwest tilted rain belt revolution off the equator during the BSISO's eastward journey in the models. The biases of the BSISO are consistent with the summer mean state, especially the vertical shear. Analysis also shows that there is a positive feedback between the intraseasonal precipitation and the summer mean precipitation. The positive feedback processes may amplify the models' biases in the BSISO simulation.

  1. Are Boreal Ovenbirds, Seiurus aurocapilla, More Prone to Move across Inhospitable Landscapes in Alberta's Boreal Mixedwood Forest than in Southern Québec's Temperate Deciduous Forest?

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    Marc Bélisle

    2007-12-01

    Full Text Available Population life-history traits such as the propensity to move across inhospitable landscapes should be shaped by exposure to landscape structure over evolutionary time. Thus, birds that recently evolved in landscapes fragmented by natural disturbances such as fire would be expected to show greater behavioral and morphological vagility relative to conspecifics that evolved under less patchy landscapes shaped by fewer and finer-scaled disturbances, i.e., the resilience hypothesis. These predictions are not new, but they remain largely untested, even for well-studied taxa such as neotropical migrant birds. We combined two experimental translocation, i.e., homing, studies to test whether Ovenbird, Seiurus aurocapilla, from the historically dynamic boreal mixedwood forest of north-central Alberta (n = 55 is more vagile than Ovenbird from historically less dynamic deciduous forest of southern Québec (n = 89. We found no regional difference in either wing loading or the response of homing Ovenbird to landscape structure. Nevertheless, this study presents a heuristic framework that can advance the understanding of boreal landscape dynamics as an evolutionary force.

  2. A 750 year ice core record of past biogenic emissions and wild fires from Siberian boreal forests

    Science.gov (United States)

    Eichler, Anja; Schwikowski, Margit; Brütsch, Sabina; Olivier, Susanne; Papina, Tatyana; Tinner, Willy

    2010-05-01

    Direct emissions from forests and forest fires represent an important source of gaseous precursors of aerosols and soot that can significantly alter the regional radiation balance. Long-term records of gaseous and particulate emissions are available for Northern America and the Amazon Basin, whereas the historical development of emissions from Siberian forests, comprising about 20% of the world's forested area, is unknown so far. Here we investigate ice core ammonium, formate, nitrate, potassium, and charcoal records for the last 750 years, representing direct biogenic and biomass burning emissions from boreal Siberian forests in the pre-industrial era. Biogenic emissions were found to be closely related to changes in temperature following variations in solar activity. Emissions from forest fire activities do not show a long-term trend, but a period of strongly increased frequency around 1600-1670. The reasons are most probably exceptionally dry conditions in the period 1550-1600 and increased temperatures. In addition, anthropogenic emissions have caused a strong increase of the ammonium and nitrate concentrations and a drop of the formate concentrations in the last 60 years.

  3. Parsimonious Model for Simulating Total Mercury and Methylmercury in Boreal Streams Based on Riparian Flow Paths and Seasonality.

    Science.gov (United States)

    Eklöf, Karin; Kraus, Andrea; Futter, Martyn; Schelker, Jakob; Meili, Markus; Boyer, Elizabeth W; Bishop, Kevin

    2015-07-01

    The complexity of mercury (Hg) biogeochemistry has made it difficult to model surface water concentrations of both total Hg (THg) and especially methylmercury (MeHg), the species of Hg having the highest potential for bioaccumulation. To simulate THg and MeHg variation in low-order streams, we have adapted a conceptual modeling framework where a continuum of lateral flows through riparian soils determines streamflow concentrations. The model was applied to seven forest catchments located in two boreal regions in Sweden spanning a range of climatic, soil, and forest management conditions. Discharge, and simulated riparian soil water concentrations profiles, represented by two calibrated parameters, were able to explain much of the variability of THg and MeHg concentrations in the streams issuing from the catchments (Nash Sutcliffe (NS) up to 0.54 for THg and 0.58 for MeHg). Model performance for all catchments was improved (NS up to 0.76 for THg and 0.85 for MeHg) by adding two to four parameters to represent seasonality in riparian soil water THg and MeHg concentrations profiles. These results are consistent with the hypothesis that riparian flow-pathways and seasonality in riparian soil concentrations are the major controls on temporal variation of THg and MeHg concentrations in low-order streams. PMID:25970167

  4. The uptake of Ni2+ and Ag+ by bacterial strains isolated from a boreal nutrient-poor bog

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    Merja Lusa

    2016-05-01

    Full Text Available We studied the uptake of Ni2+ and Ag+ by bacterial strains of Paenibacillus, Pseudomonas, Burkholderia and Rhodococcus isolated from an acidic nutrient-poor boreal bog. The tests were run in two different growth media at two temperatures; +4 °C and +20 °C. All bacterial strains removed Ni2+ and Ag+ from the solution with highest efficiencies shown by one of the Pseudomonas sp. and one of the Paenibacillus sp. strains. Highest Ni2+ uptake was found in 1% Tryptone solution, whereas the highest removal of Ag+ was obtained using 1% Yeast extract. Temperature affected the uptake of Ni2+ and Ag+, but statistically significant difference was found only for Ni2+. Based on tests carried out for the bacteria in nutrient broths and for fresh samples taken from varying depth up to seven meters from the ombrotrophic bog, from which the bacteria were isolated, we estimated that in in situ conditions of the bog the uptake of Ni2+ by bacteria accounts for approximately 0.02% of the total sorption in the uppermost moss layer, 0.01% in the peat layer, 0.02% in the gyttja layer and 0.1% in the bottom clay layer of the bog. For Ag+ the corresponding values were 2.3% in the moss layer, 0.04% in the peat layer, 0.2% in the gyttja and 0.03% in the clay layer.

  5. Estimation of potential and actual evapotranspiration of boreal forest ecosystems in the European part of Russia during the Holocene

    International Nuclear Information System (INIS)

    A simple regression model for calculating annual actual evapotranspiration (ET) and potential evapotranspiration (PET), as well as annual transpiration (TR) of mature boreal forests grown in the European part of Russia in the Holocene using paleoclimatic and paleobotanical data (air temperature, precipitation, forest species compositions) is presented. The model is based on nonlinear approximations of annual values of ET, TR and PET obtained by the Levenberg–Marquardt method using the results of numerical simulations of ET, TR and PET provided by a process-based Mixfor-SVAT model for forests with different species compositions under various thermal and moistening conditions. The results of ET, TR and PET reconstructions for the Holocene show large variability and high correlation with the air temperature pattern. Minimal values of ET and PET are obtained for the Younger Dryas cold phase (11.0–10.0 14C kyr BP) when ET varied between 320 and 370 mm yr−1 and PET varied between 410 and 480 mm yr−1. During the Late Atlantic periods of the Holocene (4.5–5.1 14C kyr BP), ET and PET reached maximal values (ET: 430–450 mm yr−1 and PET: 550–570 mm yr−1).

  6. Toward Conservation of Canada’s Boreal Forest Avifauna: Design and Application of Ecological Models at Continental Extents

    Directory of Open Access Journals (Sweden)

    Steven G. Cumming

    2010-12-01

    Full Text Available Human development is increasing pressure on North America’s mainly intact boreal forest. We outline the need for a comprehensive synthesis of existing data and for effective scientific tools to support conservation of this biome and of the birds that depend on it. To illustrate how broad collaborations can address these needs, we introduce and report on the Boreal Avian Modelling Project. This is a new partnership involving universities, government, private, and nongovernment groups that was created to develop spatially explicit, predictive models of boreal bird habitat associations across Canada. This initiative is designed to improve our understanding of the influence of environmental factors and human activities on boreal bird species, leading to spatially explicit predictive models of the distribution of av