WorldWideScience

Sample records for boreal forest ecosystems

  1. 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

  2. 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

  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. 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.

  6. 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).

  7. 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)

  8. 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

  9. 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...

  10. Influence of different tree-harvesting intensities on forest soil carbon stocks in boreal and northern temperate forest ecosystems

    DEFF Research Database (Denmark)

    Clarke, Nicholas; Gundersen, Per; Jönsson-Belyazid, Ulrika; Kjønaas, O. Janne; Persson, Tryggve; Sigurdsson, Bjarni D.; Stupak, Inge; Vesterdal, Lars

    2015-01-01

    ) stocks. This paper reviews the findings in the scientific literature concerning the effects of harvesting of different intensities on SOC stocks and fluxes in boreal and northern temperate forest ecosystems to evaluate the evidence for significant SOC losses following biomass removal. An overview of...... SOC stocks in boreal and northern temperate forest ecosystems, which is in any case species-, site- and practice-specific. Properly conducted long-term experiments are therefore necessary to enable us to clarify the relative importance of different harvesting practices on the SOC stores, the key...

  11. 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

  12. 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.

  13. Declining plant nitrogen supply and carbon accumulation in ageing primary boreal forest ecosystems

    Science.gov (United States)

    Högberg, Mona N.; Yarwood, Stephanie A.; Trumbore, Susan; Högberg, Peter

    2016-04-01

    Boreal forest soils are commonly characterized by a low plant nitrogen (N) supply. A high tree below-ground allocation of carbon (C) to roots and soil microorganisms in response to the shortage of N may lead to high microbial immobilisation of N, thus aggravating the N limitation. We studied the N supply at a Swedish boreal forest ecosystem chronosequence created by new land rising out of the sea due to iso-static rebound. The youngest soils develop with meadows by the coast, followed by a zone of dinitrogen fixing alder trees, and primary boreal conifer forest on ground up to 560 years old. With increasing ecosystem age, the proportion of microbial C out of the total soil C pool from the youngest to the oldest coniferous ecosystem was constant (c. 1-1.5%), whereas immobilised N (microbial N out of total soil N) increased and approached the levels commonly observed in similar boreal coniferous forests (c. 6-7 %), whereas gross N mineralization declined. Simultaneously, plant foliar N % decreased and the natural abundance of N-15 in the soil increased. More specifically, the difference in N-15 between plant foliage and soil increased, which is related to greater retention of N-15 relative to N-14 by ectomycorrhizal fungi as N is taken up from the soil and some N is transferred to the plant host. In the conifer forest, where these changes were greatest, we found increased fungal biomass in the F- and H-horizons of the mor-layer, in which ectomycorrhizal fungi are known to dominate (the uppermost horizon with litter and moss is dominated by saprotrophic fungi). Hence, we propose that the decreasing N supply to the plants and the subsequent decline in plant production in ageing boreal forests is linked to high tree belowground C allocation to C limited ectomycorrhizal fungi (and other soil microorganisms), a strong sink for available soil N. Data on organic matter C-14 suggested that the largest input of recently fixed plant C occurred in the younger coniferous forest

  14. Distribution and retention of cesium in Swedish boreal forest ecosystems

    International Nuclear Information System (INIS)

    The retention and distribution of cesium in forest environments are being studied at three locations in Sweden. The main part of the cesium found in the soil was recovered in horizons rich in organic matter. The cesium was retained in the soil organic matter in a more or less extractable form. As different soil types have a different distribution pattern of organic matter the distribution of cesium will depend on the forest soil type. The clay content in Swedish forest soils is in general low which will mitigate the retention of cesium in the soil mineral horizons. The cesium present in the tree was considered to be an effect of assimilation by the tissues in the canopy as well as by the roots. The redistribution of cesium within the trees was extensive which was considered to be an effect of a high mobility of cesium in the close system of a forest environment. The cesium will remain in the forest environment for a considerable time but can be removed by forest practice, by leaching out of the soil profile or by the radioactive decay. (au)

  15. Tree Species Linked to Large Differences in Ecosystem Carbon Distribution in the Boreal Forest of Alaska

    Science.gov (United States)

    Melvin, A. M.; Mack, M. C.; Johnstone, J. F.; Schuur, E. A. G.; Genet, H.; McGuire, A. D.

    2014-12-01

    In the boreal forest of Alaska, increased fire severity associated with climate change is altering plant-soil-microbial feedbacks and ecosystem carbon (C) dynamics. The boreal landscape has historically been dominated by black spruce (Picea mariana), a tree species associated with slow C turnover and large soil organic matter (SOM) accumulation. Historically, low severity fires have led to black spruce regeneration post-fire, thereby maintaining slow C cycling rates and large SOM pools. In recent decades however, an increase in high severity fires has led to greater consumption of the soil organic layer (SOL) during fire and subsequent establishment of deciduous tree species in areas previously dominated by black spruce. This shift to a more deciduous dominated landscape has many implications for ecosystem structure and function, as well as feedbacks to global C cycling. To improve our understanding of how boreal tree species affect C cycling, we quantified above- and belowground C stocks and fluxes in adjacent, mid-successional stands of black spruce and Alaska paper birch (Betula neoalaskana) that established following a 1958 fire near Fairbanks, Alaska. Although total ecosystem C pools (aboveground live tree biomass + dead wood + SOL + top 10 cm of mineral soil) were similar for the two stand types, the distribution of C among pools was markedly different. In black spruce, 78% of measured C was found in soil pools, primarily in the SOL, where spruce contained twice the C stored in paper birch (4.8 ± 0.3 vs. 2.4 ± 0.1 kg C m-2). In contrast, aboveground biomass dominated ecosystem C pools in birch forest (6.0 ± 0.3 vs. 2.5 ± 0.2 kg C m-2 in birch and spruce, respectively). Our findings suggest that tree species exert a strong influence over plant-soil-microbial feedbacks and may have long-term effects on ecosystem C sequestration and storage that feedback to the climate system.

  16. Comparing soil biogeochemical processes in novel and natural boreal forest ecosystems

    Directory of Open Access Journals (Sweden)

    S. A. Quideau

    2013-04-01

    Full Text Available Emulating the variability that exists in the natural landscape prior to disturbance should be a goal of soil reconstruction and land reclamation efforts following resource extraction. Long-term ecosystem sustainability within reclaimed landscapes can only be achieved with the re-establishment of biogeochemical processes between reconstructed soils and plants. In this study, we assessed key soil biogeochemical attributes (nutrient availability, organic matter composition, and microbial communities in reconstructed, novel, anthropogenic ecosystems covering different reclamation treatments following open-cast mining for oil extraction. We compared the attributes to those present in a range of natural soils representative of mature boreal forest ecosystems in the same area of northern Alberta. Soil nutrient availability was determined in situ with resin probes, organic matter composition was described with 13C nuclear magnetic resonance spectroscopy and soil microbial community structure was characterized using phospholipid fatty acid analysis. Significant differences among natural ecosystems were apparent in nutrient availability and seemed more related to the dominant tree cover than to soil type. When analyzed together, all natural forests differed significantly from the novel ecosystems, in particular with respect to soil organic matter composition. However, there was some overlap between the reconstructed soils and some of the natural ecosystems in nutrient availability and microbial communities, but not in organic matter characteristics. Hence, our results illustrate the importance of considering the range of natural landscape variability, and including several soil biogeochemical attributes when comparing novel, anthropogenic ecosystems to the mature ecosystems that constitute ecological targets.

  17. Comparing soil biogeochemical processes in novel and natural boreal forest ecosystems

    Science.gov (United States)

    Quideau, S. A.; Swallow, M. J. B.; Prescott, C. E.; Grayston, S. J.; Oh, S.-W.

    2013-08-01

    Emulating the variability that exists in the natural landscape prior to disturbance should be a goal of soil reconstruction and land reclamation efforts following resource extraction. Long-term ecosystem sustainability within reclaimed landscapes can only be achieved with the re-establishment of biogeochemical processes between reconstructed soils and plants. In this study, we assessed key soil biogeochemical attributes (nutrient availability, organic matter composition, and microbial communities) in reconstructed, novel, anthropogenic ecosystems, covering different reclamation treatments following open-cast mining for oil extraction. We compared the attributes to those present in a range of natural soils representative of mature boreal forest ecosystems in the same area of Northern Alberta. Soil nutrient availability was determined in situ with resin probes, organic matter composition was described with 13C nuclear magnetic resonance spectroscopy and soil microbial community structure was characterized using phospholipid fatty acid analysis. Significant differences among natural ecosystems were apparent in nutrient availability and seemed more related to the dominant tree cover than to soil type. When analyzed together, all natural forests differed significantly from the novel ecosystems, in particular with respect to soil organic matter composition. However, there was some overlap between the reconstructed soils and some of the natural ecosystems in nutrient availability and microbial communities, but not in organic matter characteristics. Hence, our results illustrate the importance of considering the range of natural landscape variability and including several soil biogeochemical attributes when comparing novel, anthropogenic ecosystems to the mature ecosystems that constitute ecological targets.

  18. 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.

  19. Natural disturbance impacts on ecosystem services and biodiversity in temperate and boreal forests.

    Science.gov (United States)

    Thom, Dominik; Seidl, Rupert

    2016-08-01

    In many parts of the world forest disturbance regimes have intensified recently, and future climatic changes are expected to amplify this development further in the coming decades. These changes are increasingly challenging the main objectives of forest ecosystem management, which are to provide ecosystem services sustainably to society and maintain the biological diversity of forests. Yet a comprehensive understanding of how disturbances affect these primary goals of ecosystem management is still lacking. We conducted a global literature review on the impact of three of the most important disturbance agents (fire, wind, and bark beetles) on 13 different ecosystem services and three indicators of biodiversity in forests of the boreal, cool- and warm-temperate biomes. Our objectives were to (i) synthesize the effect of natural disturbances on a wide range of possible objectives of forest management, and (ii) investigate standardized effect sizes of disturbance for selected indicators via a quantitative meta-analysis. We screened a total of 1958 disturbance studies published between 1981 and 2013, and reviewed 478 in detail. We first investigated the overall effect of disturbances on individual ecosystem services and indicators of biodiversity by means of independence tests, and subsequently examined the effect size of disturbances on indicators of carbon storage and biodiversity by means of regression analysis. Additionally, we investigated the effect of commonly used approaches of disturbance management, i.e. salvage logging and prescribed burning. We found that disturbance impacts on ecosystem services are generally negative, an effect that was supported for all categories of ecosystem services, i.e. supporting, provisioning, regulating, and cultural services (P paradox', documenting that disturbances can put ecosystem services at risk while simultaneously facilitating biodiversity. A detailed investigation of disturbance effect sizes on carbon storage and

  20. 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

  1. 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.

  2. Soil organic matter cycling in novel and natural boreal forest ecosystems

    Science.gov (United States)

    Norris, C. E.; Mercier Quideau, S.

    2013-12-01

    The uplands of the western boreal forest of Canada are characterized by a mosaic of pure and mixed stands of aspen (Populus tremuloides Michx.) and spruce (Picea glauca (Moench) Voss). In addition to natural ecosystems, the region is now home to novel ecosystems; i.e., ecosystems composed of reclaimed stands formed from trees planted on constructed anthropogenic soils. To understand potential differences in functioning of these novel ecosystems, we must first better understand the functioning of their natural counterparts. Here we present results on both the characterization and cycling of soil organic matter in novel and natural ecosystems found in the Athabasca oil sands region. Soil organic matter from 42 long term monitoring sites was evaluated for long chain (≥ C21) n-alkane composition. The survey showed that n-alkanes were more concentrated and had distinct signatures in natural compared to novel ecosystems. Mineral soils from reclaimed stands showed a distinct microbial community structure from natural aspen and spruce stands, as was demonstrated using phospholipid fatty acids (PLFAs) as microbial biomarkers following addition of 13C-glucose in a laboratory incubation. Further probing by compound specific analysis of the 13C-enriched PLFAs determined that microbial incorporation of 13C-glucose was different among soils. In a field incubation using 15N labeled aspen litter added to the forest floor of reclaimed, harvested and mature natural aspen stands, the microbial community readily incorporated the tracer and nitrogen was cycled to the above-ground vegetation on all sites. In addition, the amendment of leaf litter to the forest floor also increased soil moisture and soil microbial biomass on both the reclaimed and harvested sites. Utilizing stable isotope tracers in addition to a multi-faceted experimental approach has provided insightful results on the development of soil biogeochemical cycling in novel ecosystems.

  3. Importance of the forest canopy to fluxes of methyl mercury and total mercury to boreal ecosystems.

    Science.gov (United States)

    St Louis, V L; Rudd, J W; Kelly, C A; Hall, B D; Rolfhus, K R; Scott, K J; Lindberg, S E; Dong, W

    2001-08-01

    The forest canopy was an important contributor to fluxes of methyl mercury (MeHg) and total mercury (THg) to the forest floor of boreal uplands and wetlands and potentially to downstream lakes, at the Experimental Lakes Area (ELA), northwestern Ontario. The estimated fluxes of MeHg and THg in throughfall plus litterfall below the forest canopy were 2 and 3 times greater than annual fluxes by direct wet deposition of MeHg (0.9 mg of MeHg ha(-1)) and THg (71 mg of THg ha(-1)). Almost all of the increased flux of MeHg and THg under the forest canopy occurred as litterfall (0.14-1.3 mg of MeHg ha(-1) yr(-1) and 110-220 mg of THg ha(-1) yr(-1)). Throughfall added no MeHg and approximately 9 mg of THg ha(-1) yr(-1) to wet deposition at ELA, unlike in other regions of the world where atmospheric deposition was more heavily contaminated. These data suggest that dry deposition of Hg on foliage as an aerosol or reactive gaseous Hg (RGM) species is low at ELA, a finding supported by preliminary measurements of RGM there. Annual total deposition from throughfall and litterfall under a fire-regenerated 19-yr-old jack pine/birch forest was 1.7 mg of MeHg ha(-1) and 200 mg of THg ha(-1). We found that average annual accumulation of MeHg and THg in the surficial litter/fungal layer of soils since the last forest fire varied between 0.6 and 1.6 mg of MeHg ha(-1) and between 130 and 590 mg of THg ha(-1) among sites differing in drainage and soil moisture. When soil Hg accumulation sites were matched with similar sites where litterfall and throughfall were collected, measured fluxes of THg to the forest floor (sources) were similar to our estimates of longterm soil accumulation rates (sinks), suggesting that the Hg in litterfall and throughfall is a new and not a recycled input of Hg to forested ecosystems. However, further research is required to determine the proportion of Hg in litterfall that is being biogeochemically recycled within forest and wetland ecosystems and, thus, does

  4. 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

  5. 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.

  6. 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

  7. A MESO-β SCALE SIMULATION OF THE EFFECTS OF BOREAL FOREST ECOSYSTEM ON THE LOWER ATMOSPHERE

    Institute of Scientific and Technical Information of China (English)

    王汉杰; Yi-Fan LI; Aloysius K.LO

    2001-01-01

    Based on the Intensive Field Campaign (IFC-I) data of Boreal Ecosystem-Atmosphere Study(BOREAS), a three-dimensional meso-β scale model is used to simulate the effect of boreal forests on the lower atmosphere. A fine horizontal resolution of 2 km × 2 km is used in order to distinguish the vegetative heterogeneity in the boreal region. A total of 20 × 25 grid points cover the entire sub modeling area in BOREAS' South Study Area (SSA). The ecosystem types and their coverage in each grid square are extracted from the North American Land Cover Characteristics Data Base(NALCCD) generated by the U.S. Geographical Survey (USGS) and the University of Nebraska Lincoln (UNL). The topography of the study area is taken from the Digital Elevation Map (DEM)of USGS. The model outputs include the components of the energy balance budget within the canopy and at the ground, the turbulence parameters in the atmospheric boundary layer and the wind,temperature and humidity profiles extending up to a height of 1500 m. In addition to the fine time nd spatial step, the unique feature of the present model is the incorporation of both dynamic and biological effects of the Boreal forest into the model parameterization scheme. The model results compare favorably with BOREAS' IFC-1 data in 1994 when the forest was in the luxuriant growing period.

  8. Vapor pressure deficit controls on fire ignition and fire spread in boreal forest ecosystems

    Directory of Open Access Journals (Sweden)

    F. Sedano

    2014-01-01

    Full Text Available Climate-driven changes in the fire regime within boreal forest ecosystems are likely to have important effects on carbon cycling and species composition. In the context of improving fire management options and developing more realistic scenarios of future change, it is important to understand how meteorology regulates different fire processes, including ignition, daily fire spread rates, and cumulative annual burned area. Here we combined MODIS active fires (MCD14ML, MODIS imagery (MOD13A1 and ancillary historic fire perimeter information to produce a dataset of daily fire spread maps of Alaska for the period 2002–2011. This approach provided a spatial and temporally continuous representation of fire progression and a precise identification of ignition and extinction locations and dates for each wildfire. The fire-spread maps were analyzed together with daily vapor pressure deficit (VPD observations from the North American Regional Reanalysis (NARR and lightning strikes from the Alaska Lightning Detection Network (ALDN. We found a significant relationship between daily VPD and probability that a lightning strike would develop into a fire ignition. In the first 5 days after ignition, above average VPD increased the probability that fires would grow to large or very large sizes. Strong relationships also were identified between VPD and burned area at several levels of temporal and spatial aggregation. As a consequence of regional coherence in meteorology, ignition, daily fire spread rates, and fire extinction events were often synchronized across different fires in interior Alaska. At a regional scale, the sum of positive VPD anomalies during the fire season was positively correlated with annual burned area during the NARR era (1979–2011; R2 = 0.45. Some of the largest fires we mapped had slow initial growth, indicating opportunities may exist for suppression efforts to adaptively manage these forests for climate change. The results of our

  9. 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)

  10. Can We Use Forest Inventory Mapping as a Coarse Filter in Ecosystem Based Management in the Black Spruce Boreal Forest?

    OpenAIRE

    Chafi Chaieb; Nicole J Fenton; Benoit Lafleur; Yves Bergeron

    2015-01-01

    Forest inventory mapping is used worldwide to describe forests at a large spatial scale via the delimitation of portions of the landscape that are structurally homogeneous. Consequently, there is a significant amount of descriptive forest data in forest inventory maps, particularly with the development of ecosystem classification, which represents a significant potential for use in ecosystem based management. With this study we propose to test whether forest inventory maps can be used to desc...

  11. Inclusion of Additional Plant Species and Trait Information in Dynamic Vegetation Modeling of Arctic Tundra and Boreal Forest Ecosystem

    Science.gov (United States)

    Euskirchen, E. S.; Patil, V.; Roach, J.; Griffith, B.; McGuire, A. D.

    2015-12-01

    Dynamic vegetation models (DVMs) have been developed to model the ecophysiological characteristics of plant functional types in terrestrial ecosystems. They have frequently been used to answer questions pertaining to processes such as disturbance, plant succession, and community composition under historical and future climate scenarios. While DVMs have proved useful in these types of applications, it has often been questioned if additional detail, such as including plant dynamics at the species-level and/or including species-specific traits would make these models more accurate and/or broadly applicable. A sub-question associated with this issue is, 'How many species, or what degree of functional diversity, should we incorporate to sustain ecosystem function in modeled ecosystems?' Here, we focus on how the inclusion of additional plant species and trait information may strengthen dynamic vegetation modeling in applications pertaining to: (1) forage for caribou in northern Alaska, (2) above- and belowground carbon storage in the boreal forest and lake margin wetlands of interior Alaska, and (3) arctic tundra and boreal forest leaf phenology. While the inclusion of additional information generally proved valuable in these three applications, this additional detail depends on field data that may not always be available and may also result in increased computational complexity. Therefore, it is important to assess these possible limitations against the perceived need for additional plant species and trait information in the development and application of dynamic vegetation models.

  12. Integrating modelling and remote sensing to identify ecosystem performance anomalies in the boreal forest, Yukon River Basin, Alaska

    Science.gov (United States)

    Wylie, B.K.; Zhang, L.; Bliss, Norman B.; Ji, Lei; Tieszen, Larry L.; Jolly, W. M.

    2008-01-01

    High-latitude ecosystems are exposed to more pronounced warming effects than other parts of the globe. We develop a technique to monitor ecological changes in a way that distinguishes climate influences from disturbances. In this study, we account for climatic influences on Alaskan boreal forest performance with a data-driven model. We defined ecosystem performance anomalies (EPA) using the residuals of the model and made annual maps of EPA. Most areas (88%) did not have anomalous ecosystem performance for at least 6 of 8 years between 1996 and 2004. Areas with underperforming EPA (10%) often indicate areas associated with recent fires and areas of possible insect infestation or drying soil related to permafrost degradation. Overperforming areas (2%) occurred in older fire recovery areas where increased deciduous vegetation components are expected. The EPA measure was validated with composite burn index data and Landsat vegetation indices near and within burned areas.

  13. 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.

  14. Mobility of radiocaesium in boreal forest ecosystems: Influence of precipitation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Steinnes, E. [Department of Chemistry, Norwegian University of Science and Technology (Norway); Gjelsvik, R.; Skuterud, L.; Thoerring, H. [Norwegian Radiation Protection Authority (Norway)

    2014-07-01

    Mobility and plant uptake of Cs in soils is generally limited by the presence of clay minerals in the soil. However, cations supplied by precipitation may substantially influence the mobility of radiocaesium in natural surface soil and subsequent transfer to food chains. The chemical composition of precipitation shows substantial variation among different areas in Norway for two main reasons. At sites close to the coast the atmospheric supply of marine cations and anions is many-fold greater than in regions shielded from marine influence by mountains. The southernmost part of the country has been, and still is, substantially affected by soil acidification due to long-range atmospheric transport of acidifying substances from areas elsewhere in Europe. This may explain a much higher greater uptake of {sup 137}Cs from the Chernobyl accident in moose in this region than elsewhere (Steinnes et al., 2009), in spite of the fact that some areas farther north received substantially greater fallout. Similarly a much greater transfer of {sup 137}Cs to natural birch forest vegetation is evident from the more acidified soils in the south than in comparable ecosystems elsewhere in the country (Thoerring et al., 2012). Repeated recordings of activity levels in natural surface soils showed faster leaching of Chernobyl {sup 137}Cs relative to inland areas not only in the south but also in coastal areas farther north (Gjelsvik and Steinnes, 2013), indicating that the amounts of marine cations in precipitation also has an appreciable effect on the Cs leaching. The geographical leaching differences still became less prominent with time. Recent lysimeter experiments with undisturbed soil columns obtained from an area receiving high radiocaesium deposition from the Chernobyl accident, applying precipitation with ionic composition characteristic of the different regions mentioned above, did not change the current depth distribution of {sup 137}Cs. However, acidic precipitation increased

  15. Mobility of radiocaesium in boreal forest ecosystems: Influence of precipitation chemistry

    International Nuclear Information System (INIS)

    Mobility and plant uptake of Cs in soils is generally limited by the presence of clay minerals in the soil. However, cations supplied by precipitation may substantially influence the mobility of radiocaesium in natural surface soil and subsequent transfer to food chains. The chemical composition of precipitation shows substantial variation among different areas in Norway for two main reasons. At sites close to the coast the atmospheric supply of marine cations and anions is many-fold greater than in regions shielded from marine influence by mountains. The southernmost part of the country has been, and still is, substantially affected by soil acidification due to long-range atmospheric transport of acidifying substances from areas elsewhere in Europe. This may explain a much higher greater uptake of 137Cs from the Chernobyl accident in moose in this region than elsewhere (Steinnes et al., 2009), in spite of the fact that some areas farther north received substantially greater fallout. Similarly a much greater transfer of 137Cs to natural birch forest vegetation is evident from the more acidified soils in the south than in comparable ecosystems elsewhere in the country (Thoerring et al., 2012). Repeated recordings of activity levels in natural surface soils showed faster leaching of Chernobyl 137Cs relative to inland areas not only in the south but also in coastal areas farther north (Gjelsvik and Steinnes, 2013), indicating that the amounts of marine cations in precipitation also has an appreciable effect on the Cs leaching. The geographical leaching differences still became less prominent with time. Recent lysimeter experiments with undisturbed soil columns obtained from an area receiving high radiocaesium deposition from the Chernobyl accident, applying precipitation with ionic composition characteristic of the different regions mentioned above, did not change the current depth distribution of 137Cs. However, acidic precipitation increased the mobility of Cs added

  16. Proceedings of a symposium on the reclamation and restoration of boreal peatland and forest ecosystems : towards a sustainable future

    Energy Technology Data Exchange (ETDEWEB)

    Bhatti, J. [Natural Resources Canada, Ottawa, ON (Canada); Foote, L.; Moran, S. [Alberta Univ., Edmonton, AB (Canada); Nadeau, L. [Northern Alberta Inst. of Technology, Edmonton, AB (Canada); Rochefort, L. [Laval Univ., Quebec City, PQ (Canada); Short, P. [Canadian Sphagnum Peat Moss Association, St. Albert, AB (Canada); Vitt, D.H. [Southern Illinois Univ., Carbondale, IL (United States); Wieder, K. [Villanova Univ., Villanova, PA (United States)] (comps.)

    2010-07-01

    Disturbances in Canada's boreal forest occur in both upland forests and in peatlands. These disturbances originate from both anthropogenic and natural causes, particularly fire. Techniques for the restoration, as well as the reclamation of peatlands and forests impacted by agriculture, urban development, or oil and gas activities, have made significant advancement over the last decade and these techniques need to be incorporated into the regulation and management of peatland and forest ecosystems. This symposium addressed the issue of how this research is affected by climate change. The sessions were entitled: (1) reclaiming forest and forest soils impacted by oil and gas production, (2) influence of oil sands development on forest communities, (3) understanding the importance of peatland and forest carbon in the twenty-first century, (4) reclaiming wetlands on mined oil sands tailing, (5) disturbance in peatlands and its relevance to minimizing disturbance footprints and informing reclamation efforts, and (6) restoration and management of harvested peatlands. The symposium featured 37 presentations, of which 6 have been catalogued separately for inclusion in this database. refs., tabs., figs.

  17. Application of a catchment characterization hydrologic model for exploring parameter sensitivities in a boreal forest, discontinuous permafrost ecosystem

    Science.gov (United States)

    Morton, D.; Bolton, W. R.; Young, J.; Hinzman, L. D.

    2013-12-01

    Many of the expected climate-driven changes in sub-arctic ecosystems, such as increased temperature and precipitation, decreased permafrost extent, tree-line expansion and vegetation composition, have been identified as potential mechanisms that may lead to shifts in the Arctic Ocean freshwater budget. Understanding the feedback mechanisms of the water cycle are paramount, in that small changes may result in dramatic threshold changes in the hydrology, ecology and surface energy balance. As part of a study on how vegetation water use and permafrost dynamics impact stream flow in the boreal forest discontinuous permafrost zone, we are integrating a vegetation water use model and a simple, first-order, non-linear hydrological model, utilizing a Bayesian analysis approach to fully account for and propagate uncertainty through this modeling system. With an overall goal of improving parameterizations of large-scale hydrological models, we are constructing a simple and portable hydrologic model within a Bayesian framework. Thus, uncertainty associated with the evaporation (E), transpiration (T), precipitation (P), and streamflow (Q) submodels will be propagated into the final hydrology model. An immediate application of the modeling system will be used to explore the hydrological impacts of different vegetation distributions found in the boreal forest. In this work, we describe the basic structure of this flexible, object-oriented model and test its performance against collected basin data from headwater catchments of varying permafrost extent and ecosystem structure (deciduous versus coniferous vegetation). We will also do analyses to assess model sensitivity to each parameter (E, T, P, Q) and to different climate scenarios. This model is a major advancement for hydrological models that will aid in assessing sources of uncertainty in boreal hydrological systems.

  18. Recent Tree-growth Responses to Warming Vary by Geographic Region and Ecosystem Type within the Boreal Forest-tundra Transition Zone in Alaska

    Science.gov (United States)

    Sherriff, R.; Miller, A. E.

    2015-12-01

    A critical concern for boreal ecosystems centers on broad-scale responses to warming; i.e., where warming will lead to declining growth and mortality, or enhanced growth and greater productivity. However, few studies have synthesized tree growth along biogeographic gradients in an attempt to address this issue. We sought to develop a broader understanding of how trees have responded to recent warming for a dominant conifer species from the southern boreal to the western forest margin, an area expected to show signs of an early-stage boreal biome shift. A new 30-site network of ring-width chronologies (1216 trees >4cm dbh) were evaluated for growth differences in Picea glauca across low-elevation, closed forests, open woodlands, and altitudinal treeline from southern interior boreal forest to the western forest-tundra margin. Regional temperature records were used to evaluate 1) whether tree growth near western treeline, which experiences cooler summers but warmer winters than in the interior, showed greater sensitivity to temperature than interior sites, 2) if the temperature-growth response varied through time, across ecosystem types, and by tree age, and 3) if there was a temperature-growth threshold. Positive growth trends since the 1980s in many open stands were consistent with the predicted expansion of western and altitudinal treeline. However, years with temperatures >13oC corresponded with a growth plateau or decline at all but the altitudinal treeline sites regardless of geographic location. Closed-canopy stands showed growth declines, high spruce beetle activity, and less resiliency to further warming. Warming leads to markedly different responses according to ecosystem type and biogeographical setting at the boreal forest-tundra margin. Low-elevation forests are less resilient to further warming where temperatures have already reached threshold levels and further spruce beetle outbreaks occur, even at the western margin of boreal forest.

  19. Sensitivity of Spruce/Moss Boreal Forest Net Ecosystem Productivity to Seasonal Anomalies in Weather

    Science.gov (United States)

    Frolking, Steve

    1997-01-01

    Abstract. A process-oriented, daily time step model of a spruce/moss boreal ecosystem simulated 1994 and 1995 productivity for a Boreal Ecosystem-Atmosphere Study site near Thompson, Manitoba. Simulated black spruce net primary productivity (NPP) was 139 g C m(exp -2) in 1994 and 112 in 1995; feathermoss NPP was 13.0 g C m(exp -2) in 1994 and 9.7 in 1995; decomposition was 126 g C m(exp -2) in 1994 and 130 in 1995; net ecosystem productivity (NEP) was an uptake of 26.3 g C m(exp -2)in 1994 and 2.5 in 1995. A very dry period for the first half of the 1995 summer was the major cause of that year's lower productivity. Sensitivity simulations explored the impact of 2-month long warmer, cooler, wetter, and drier spells on ecosystem productivity. Warmer summers decreased spruce NPP, moss NPP, and NEP; cooler summers had the opposite effect. Earlier snowmelt (due to either warmer spring temperatures or reduced winter precipitation) increased moss and spruce NPP; later snowmelt had the opposite effect. The largest effect on decomposition was a 5% reduction due to a drier summer. One-month droughts (April through October) were also imposed on 1975 base year weather. Early summer droughts reduced moss annual NPP by -30-40%; summer droughts reduced spruce annual NPP by 10%; late summer droughts increased moss NPP by about 20% due to reduced respiration; May to September monthly droughts reduced heterotrophic respiration by about 10%. Variability in NEP was up to roughly +/- 35%. Finally, 1975 growing season precipitation was redistributed into frequent, small rainstorms and infrequent, large rainstorms. These changes had no effect on spruce NPP. Frequent rainstorms increased decomposition by a few percent, moss NPP by 50%, and NEP by 20%. Infrequent rainstorms decreased decomposition by 5%, moss NPP by 50% and NEP by 15%. The impact of anomalous weather patterns on productivity of this ecosystem depended on their timing during the year. Multiyear data sets are necessary to

  20. 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

  1. 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).

  2. Ecosystem types of boreal forest in the North Klondike River Valley, Yukon Territory, Canada, and their productivity potentials.

    Science.gov (United States)

    Kojima, S

    1996-01-01

    Vegetation, environmental characteristics, and forest productivity were studied in the boreal forest in the North Klondike River Valley, Yukon Territory, Canada. The concept and approach of biogeoclimatic ecosystem classification were followed. For the treed vegetation, five ecosystem types were distinguished based on vegetation structure and physical and chemical properties of soils. They were: 1) spruce-lichen type, 2) spruce-moss type, 3) spruce-Equisetum type, 4) spruce-willow type, and 5) bog forest type. These types were differentiated mainly by moisture regime and base status of soils. The sequence of the ecosystem types reflected their topographical position from slope summit to valley bottom. The spruce-lichen type developed in the driest and nutritionally impoverished habitats, the spruce-Equisetum type occurred in moist and nutritionally enriched sites, and the spruce-moss type was found in between them. The bog forest type occurred where peat had accumulated sufficiently to generate ombrotrophic conditions in habitats of high water table underlain with permafrost. The spruce-willow type developed along small creeks where substrates were very coarse. Tree growth characteristics were measured, except for the bog forest type that did not have trees over 5 m tall. Total volume of standing trees ranged from 29 to 582 m(3)/ha, with an overall mean of 216.9 m(3)/ha. The spruce-Equisetum type exhibited the highest figure, 413.5 m(3)/ha, while spruce-lichen type the lowest one, 87.7 m(3)/ha. Mean annual increment ranged from 0.15 to 2.66 m(3)/ha, with an overall mean of 1.10 m(3)/ha. A similar tendency was noted for all other forestry characteristics, i.e., the spruce-Equisetum type showed the highest productivity while the spruce-lichen type the lowest. This tendency was considered to be attributed to the availability of moisture and basic cations in soils. PMID:24198010

  3. Role of de novo biosynthesis in ecosystem scale monoterpene emissions from a boreal Scots pine forest

    OpenAIRE

    Taipale, R.; Kajos, M. K.; J. Patokoski; Rantala, P.; Ruuskanen, T. M.; J. Rinne

    2010-01-01

    Monoterpene emissions from Scots pine have traditionally been assumed to originate as evaporation from specialized storage pools. More recently, the significance of de novo emissions, originating directly from monoterpene biosynthesis, has been recognized. To study the role of biosynthesis in the ecosystem scale, we measured monoterpene emissions from a Scots pine dominated forest in southern Finland using the disjunct eddy covariance method combined with proton transfer reaction mass ...

  4. Role of de novo biosynthesis in ecosystem scale monoterpene emissions from a boreal Scots pine forest

    OpenAIRE

    Taipale, R.; Kajos, M. K.; J. Patokoski; Rantala, P.; Ruuskanen, T. M.; J. Rinne

    2011-01-01

    Monoterpene emissions from Scots pine have traditionally been assumed to originate as evaporation from specialized storage pools. More recently, the significance of de novo emissions, originating directly from monoterpene biosynthesis, has been recognized. To study the role of biosynthesis at the ecosystem scale, we measured monoterpene emissions from a Scots pine dominated forest in southern Finland using the disjunct eddy covariance method combined with proton transfer reaction mass spectro...

  5. Functional Responses and Resilience of Boreal Forest Ecosystem after Reduction of Deer Density

    OpenAIRE

    Bachand, Marianne; Pellerin, Stéphanie; Moretti, Marco; Aubin, Isabelle; Tremblay, Jean-Pierre; Steeve D. Côté; Poulin, Monique

    2014-01-01

    The functional trait-based approach is increasingly used to predict responses of ecological communities to disturbances, but most studies target a single taxonomic group. Here, we assessed the resilience of a forest ecosystem to an overabundant herbivore population by assessing changes in 19 functional traits for plant, 13 traits for ground beetle and 16 traits for songbird communities after six years of controlled browsing on Anticosti Island (Quebec, Canada). Our results indicated that plan...

  6. Can We Use Forest Inventory Mapping as a Coarse Filter in Ecosystem Based Management in the Black Spruce Boreal Forest?

    Directory of Open Access Journals (Sweden)

    Chafi Chaieb

    2015-04-01

    Full Text Available Forest inventory mapping is used worldwide to describe forests at a large spatial scale via the delimitation of portions of the landscape that are structurally homogeneous. Consequently, there is a significant amount of descriptive forest data in forest inventory maps, particularly with the development of ecosystem classification, which represents a significant potential for use in ecosystem based management. With this study we propose to test whether forest inventory maps can be used to describe not only stand characteristics but also dynamic processes. The results indicate that stand types identifiable in forest inventory maps do not in fact represent unique developmental stages, but rather confound stands at multiple developmental stages that may be undergoing different ecological processes. The reasons for this are linked to both the interaction between succession, fire severity and paludification. Finally, some aspects of the process of forest inventory mapping itself contribute to the disjunction between forest types and forest succession. Given the low similarity between spruce mapping types and their actual description following forest inventories, it would be too ambitious to infer the dynamic aspects of spruce forest by map units.

  7. Enabling intelligent copernicus services for carbon and water balance modeling of boreal forest ecosystems - North State

    Science.gov (United States)

    Häme, Tuomas; Mutanen, Teemu; Rauste, Yrjö; Antropov, Oleg; Molinier, Matthieu; Quegan, Shaun; Kantzas, Euripides; Mäkelä, Annikki; Minunno, Francesco; Atli Benediktsson, Jon; Falco, Nicola; Arnason, Kolbeinn; Storvold, Rune; Haarpaintner, Jörg; Elsakov, Vladimir; Rasinmäki, Jussi

    2015-04-01

    The objective of project North State, funded by Framework Program 7 of the European Union, is to develop innovative data fusion methods that exploit the new generation of multi-source data from Sentinels and other satellites in an intelligent, self-learning framework. The remote sensing outputs are interfaced with state-of-the-art carbon and water flux models for monitoring the fluxes over boreal Europe to reduce current large uncertainties. This will provide a paradigm for the development of products for future Copernicus services. The models to be interfaced are a dynamic vegetation model and a light use efficiency model. We have identified four groups of variables that will be estimated with remote sensed data: land cover variables, forest characteristics, vegetation activity, and hydrological variables. The estimates will be used as model inputs and to validate the model outputs. The earth observation variables are computed as automatically as possible, with an objective to completely automatic estimation. North State has two sites for intensive studies in southern and northern Finland, respectively, one in Iceland and one in state Komi of Russia. Additionally, the model input variables will be estimated and models applied over European boreal and sub-arctic region from Ural Mountains to Iceland. The accuracy assessment of the earth observation variables will follow statistical sampling design. Model output predictions are compared to earth observation variables. Also flux tower measurements are applied in the model assessment. In the paper, results of hyperspectral, Sentinel-1, and Landsat data and their use in the models is presented. Also an example of a completely automatic land cover class prediction is reported.

  8. Behaviour of 137Cs in the Boreal forest ecosystem of central Sweden

    International Nuclear Information System (INIS)

    Behaviour of Chernobyl fallout 137Cs in a coniferous forest ecosystem in central Sweden was investigated between 1990 and 1994. Results demonstrated that forest soil belongs to nutrient deficient type, and deposited fallout 137Cs from Chernobyl nuclear accident (CNA) was retained (85%) in the upper 5 cm of humic forest soil layer, with a venial migration deeper into soil profile. No correlation between forest soil exchangeable and total potassium (K+) and 137Cs transfer parameters was observed. However, addition of K+, found to efficiently reduce 137Cs uptake by sheep's fescue and the addition of stable caesium (133Cs+) enhanced it. The addition of ammonium (NH4+) was slightly stimulating the uptake of 137Cs by sheep's fescue in the first cut only. Field plants showed a considerably reduction in their 137Cs activity concentrations. Relative to their 137Cs levels of 1986-89, a little reduction in heather (16%) occurred eight years after CNA. In contrast the reductions in lingonberry and bilberry were 87% and 68%, respectively. Three fractions of forest soil bound 137Cs were observed due to sequential extraction procedure (SEP). The first, is easily extractable 137Cs fraction (F1+F2), it comprises 22% of total forest soil 137Cs inventory in the upper 5 cm layer. The second, is soil organically and biologically bound 137Cs (F3+F4) comprises about 30% of soil bound 137Cs. This fraction might be accounted for long-term soil available 137Cs for plant uptake after bio-degradation processes by soil microorganisms. The third, is the residual fraction (F5), it comprises more than 35% of total forest soil 137Cs inventory, and may be associated with soil components which are probably of organic nature. Sorption of 137Cs by zeolite (Mordenite) revealed that soil bound 137Cs is to some extent more mobile in forest soils with high OM% and low pH than those with low OM%. 99 refs

  9. Effects of Conversion from Boreal Forest to Arctic Steppe on Soil Communities and Ecosystem Carbon Pools

    Science.gov (United States)

    Han, P. D.; Natali, S.; Schade, J. D.; Zimov, N.; Zimov, S. A.

    2014-12-01

    The end of the Pleistocene marked the extinction of a great variety of arctic megafauna, which, in part, led to the conversion of arctic grasslands to modern Siberian larch forest. This shift may have increased the vulnerability of permafrost to thawing because of changes driven by the vegetation shift; the higher albedo of grassland and low insulation of snow trampled by animals may have decreased soil temperatures and reduced ground thaw in the grassland ecosystem, resulting in protection of organic carbon in thawed soil and permafrost. To test these hypothesized impacts of arctic megafauna, we examined an experimental reintroduction of large mammals in northeast Siberia, initiated in 1988. Pleistocene Park now contains 23 horses, three musk ox, one bison, and several moose in addition to the native fauna. The park is 16 square km with a smaller enclosure (animals spend most of their time and our study was focused. We measured carbon-pools in forested sites (where scat surveys showed low animal use), and grassy sites (which showed higher use), within the park boundaries. We also measured thaw depth and documented the soil invertebrate communities in each ecosystem. There was a substantial difference in number of invertebrates per kg of organic soil between the forest (600 ± 250) and grassland (300 ± 250), though these differences were not statistically significant they suggest faster nutrient turnover in the forest or a greater proportion of decomposition by invertebrates than other decomposers. While thaw depth was deeper in the grassland (60 ± 4 cm) than in the forest (40 ± 6 cm), we did not detect differences in organic layer depth or percent organic matter between grassland and forest. However, soil in the grassland had higher bulk density, and higher carbon stocks in the organic and mineral soil layers. Although deeper thaw depth in the grassland suggests that more carbon is available to microbial decomposers, ongoing temperature monitoring will help

  10. Role of de novo biosynthesis in ecosystem scale monoterpene emissions from a boreal Scots pine forest

    Directory of Open Access Journals (Sweden)

    R. Taipale

    2010-11-01

    Full Text Available Monoterpene emissions from Scots pine have traditionally been assumed to originate as evaporation from specialized storage pools. More recently, the significance of de novo emissions, originating directly from monoterpene biosynthesis, has been recognized. To study the role of biosynthesis in the ecosystem scale, we measured monoterpene emissions from a Scots pine dominated forest in southern Finland using the disjunct eddy covariance method combined with proton transfer reaction mass spectrometry. The interpretation of the measurements was based on a hybrid emission algorithm describing both de novo and pool emissions. During the measurement period May–August 2007, the monthly medians of daytime emissions were 170, 280, 180, and 180 μg m−2 h−1. The emission potential for both de novo and pool emissions exhibited a decreasing summertime trend. The ratio of the de novo emission potential to the total emission potential varied between 30% and 46%. Although the monthly changes were not significant, the ratio always differed statistically from zero, i.e., the role of de novo biosynthesis was evident. The hybrid approach showed promising potential for the improvement of the ecosystem scale emission modelling. Given this feature and the significant role of biosynthesis, we recommend incorporating both de novo and pool emissions into the monoterpene emission algorithms for Scots pine dominated forests.

  11. Role of de novo biosynthesis in ecosystem scale monoterpene emissions from a boreal Scots pine forest

    Science.gov (United States)

    Taipale, R.; Kajos, M. K.; Patokoski, J.; Rantala, P.; Ruuskanen, T. M.; Rinne, J.

    2011-08-01

    Monoterpene emissions from Scots pine have traditionally been assumed to originate as evaporation from specialized storage pools. More recently, the significance of de novo emissions, originating directly from monoterpene biosynthesis, has been recognized. To study the role of biosynthesis at the ecosystem scale, we measured monoterpene emissions from a Scots pine dominated forest in southern Finland using the disjunct eddy covariance method combined with proton transfer reaction mass spectrometry. The interpretation of the measurements was based on a correlation analysis and a hybrid emission algorithm describing both de novo and pool emissions. During the measurement period May-August 2007, the monthly medians of daytime emissions were 200, 290, 180, and 200 μg m-2 h-1. The emissions were partly light dependent, probably due to de novo biosynthesis. The emission potential for both de novo and pool emissions exhibited a decreasing summertime trend. The ratio of the de novo emission potential to the total emission potential varied between 30 % and 46 %. Although the monthly changes were not significant, the ratio always differed statistically from zero, suggesting that the role of de novo biosynthesis was observable. Given the uncertainties in this study, we conclude that more accurate estimates of the contribution of de novo emissions are required for improving monoterpene emission algorithms for Scots pine dominated forests.

  12. Role of de novo biosynthesis in ecosystem scale monoterpene emissions from a boreal Scots pine forest

    Directory of Open Access Journals (Sweden)

    R. Taipale

    2011-08-01

    Full Text Available Monoterpene emissions from Scots pine have traditionally been assumed to originate as evaporation from specialized storage pools. More recently, the significance of de novo emissions, originating directly from monoterpene biosynthesis, has been recognized. To study the role of biosynthesis at the ecosystem scale, we measured monoterpene emissions from a Scots pine dominated forest in southern Finland using the disjunct eddy covariance method combined with proton transfer reaction mass spectrometry. The interpretation of the measurements was based on a correlation analysis and a hybrid emission algorithm describing both de novo and pool emissions. During the measurement period May–August 2007, the monthly medians of daytime emissions were 200, 290, 180, and 200 μg m−2 h−1. The emissions were partly light dependent, probably due to de novo biosynthesis. The emission potential for both de novo and pool emissions exhibited a decreasing summertime trend. The ratio of the de novo emission potential to the total emission potential varied between 30 % and 46 %. Although the monthly changes were not significant, the ratio always differed statistically from zero, suggesting that the role of de novo biosynthesis was observable. Given the uncertainties in this study, we conclude that more accurate estimates of the contribution of de novo emissions are required for improving monoterpene emission algorithms for Scots pine dominated forests.

  13. Functional responses and resilience of boreal forest ecosystem after reduction of deer density.

    Directory of Open Access Journals (Sweden)

    Marianne Bachand

    Full Text Available The functional trait-based approach is increasingly used to predict responses of ecological communities to disturbances, but most studies target a single taxonomic group. Here, we assessed the resilience of a forest ecosystem to an overabundant herbivore population by assessing changes in 19 functional traits for plant, 13 traits for ground beetle and 16 traits for songbird communities after six years of controlled browsing on Anticosti Island (Quebec, Canada. Our results indicated that plants were more responsive to 6 years of reduced browsing pressure than ground beetles and songbirds. However, co-inertia analysis revealed that ground beetle communities responded in a similar way than plant communities with stronger relationships between plant and ground beetle traits at reduced deer density, a pattern not detected between plant and songbird. High deer density favored plants species that reproduce vegetatively and with abiotic pollination and seed dispersal, traits implying little interaction with animal. On the other hand, traits found at reduced deer density mostly involved trophic interaction. For example, plants in this treatment had fleshy fruits and large seeds dispersed by birds or other animals whereas ground beetle species were carnivorous. Overall, our results suggest that plant communities recovered some functional components to overabundant herbivore populations, since most traits associated with undisturbed forests were reestablished after six years of deer reduction. The re-establishment of functional plant communities with traits involving trophic interaction induces changes in the ground-beetle trait community, but forest structure remains likely insufficiently heterogeneous to shift the songbird trait community within six years.

  14. Functional responses and resilience of boreal forest ecosystem after reduction of deer density.

    Science.gov (United States)

    Bachand, Marianne; Pellerin, Stéphanie; Moretti, Marco; Aubin, Isabelle; Tremblay, Jean-Pierre; Côté, Steeve D; Poulin, Monique

    2014-01-01

    The functional trait-based approach is increasingly used to predict responses of ecological communities to disturbances, but most studies target a single taxonomic group. Here, we assessed the resilience of a forest ecosystem to an overabundant herbivore population by assessing changes in 19 functional traits for plant, 13 traits for ground beetle and 16 traits for songbird communities after six years of controlled browsing on Anticosti Island (Quebec, Canada). Our results indicated that plants were more responsive to 6 years of reduced browsing pressure than ground beetles and songbirds. However, co-inertia analysis revealed that ground beetle communities responded in a similar way than plant communities with stronger relationships between plant and ground beetle traits at reduced deer density, a pattern not detected between plant and songbird. High deer density favored plants species that reproduce vegetatively and with abiotic pollination and seed dispersal, traits implying little interaction with animal. On the other hand, traits found at reduced deer density mostly involved trophic interaction. For example, plants in this treatment had fleshy fruits and large seeds dispersed by birds or other animals whereas ground beetle species were carnivorous. Overall, our results suggest that plant communities recovered some functional components to overabundant herbivore populations, since most traits associated with undisturbed forests were reestablished after six years of deer reduction. The re-establishment of functional plant communities with traits involving trophic interaction induces changes in the ground-beetle trait community, but forest structure remains likely insufficiently heterogeneous to shift the songbird trait community within six years. PMID:24587362

  15. Discrimination against C18O16O during photosynthesis and the oxygen isotope ratio of respired CO2 in boreal forest ecosystems

    International Nuclear Information System (INIS)

    Our objective was to analyze factors that influence changes in the oxygen isotope ratio (δ18O) of atmospheric CO2 within boreal forest ecosystems. We made measurements in the three major forest types (black spruce, jack pine, and aspen) at the southern and northern ends of the boreal forest in central Canada. This research was part of a larger study, the Boreal Ecosystem-Atmosphere Study (BOREAS). In terrestrial ecosystems the δ18O value of atmospheric CO2 is strongly influenced by isotope effects that occur during photosynthesis and respiration. Of primary importance is an equilibrium isotope effect that occurs between oxygen in CO2 and oxygen in soil water and plant chloroplast water. During the equilibrium reaction the oxygen isotope ratio of CO2 becomes enriched in 18O relative to that of water. We measured seasonal changes in the oxygen isotope ratio of (1) water input to the ecosystems (precipitation), (2) water taken up by the major plant species from the soil (plant stem water), and (3) water in plant leaves. We used this information in calculations of isotope discrimination during photosynthesis and soil respiration. Discrimination against C18O16O during photosynthetic gas exchange (ΔA) (influenced by equilibration with chloroplast water) averaged approximately 21‰ at midday and was similar for all forest types. In contrast, CO2 released during plant and soil respiration had an average δ18O value of −14.4‰ but was less depleted in 18O than would be expected for respired CO2 in isotopic equilibrium with soil water. This effect was most pronounced in black spruce sites because of the extensive coverage of moss on the ground surface and the observation that water in the upper moss layers can have an oxygen isotope ratio substantially different from water in deeper soil layers. (author)

  16. Discrimination against C18O16O during photosynthesis and the oxygen isotope ratio of respired CO2 in boreal forest ecosystems

    Science.gov (United States)

    Flanagan, Lawrence B.; Brooks, J. Renee; Varney, Gregory T.; Ehleringer, James R.

    1997-03-01

    Our objective was to analyze factors that influence changes in the oxygen isotope ratio (δ18O) of atmospheric CO2 within boreal forest ecosystems. We made measurements in the three major forest types (black spruce, jack pine, and aspen) at the southern and northern ends of the boreal forest in central Canada. This research was part of a larger study, the Boreal Ecosystem-Atmosphere Study (BOREAS). In terrestrial ecosystems the δ18O value of atmospheric CO2 is strongly influenced by isotope effects that occur during photosynthesis and respiration. Of primary importance is an equilibrium isotope effect that occurs between oxygen in CO2 and oxygen in soil water and plant chloroplast water. During the equilibrium reaction the oxygen isotope ratio of CO2 becomes enriched in 18O relative to that of water. We measured seasonal changes in the oxygen isotope ratio of (1) water input to the ecosystems (precipitation), (2) water taken up by the major plant species from the soil (plant stem water), and (3) water in plant leaves. We used this information in calculations of isotope discrimination during photosynthesis and soil respiration. Discrimination against C18O16O during photosynthetic gas exchange (ΔA) (influenced by equilibration with chloroplast water) averaged approximately 21‰ at midday and was similar for all forest types. In contrast, CO2 released during plant and soil respiration had an average δ18O value of -14.4‰ but was less depleted in 18O than would be expected for respired CO2 in isotopic equilibrium with soil water. This effect was most pronounced in black spruce sites because of the extensive coverage of moss on the ground surface and the observation that water in the upper moss layers can have an oxygen isotope ratio substantially different from water in deeper soil layers.

  17. Impact of Temperature Increase and Precipitation Alteration at Climate Change on Forest Productivity and Soil Carbon in Boreal Forest Ecosystems in Canada and Russia: Simulation Approach with the EFIMOD Model

    OpenAIRE

    Chertov, Oleg

    2010-01-01

    The results of EFIMOD model simulations to specify a possible effect of forthcoming climate warming allowed for preliminary quantification of the effects of this environmental change on boreal forests in North America and Europe. In Central Canada, the black spruce and jack pine forests respond to climate warming, fire, harvesting and insects by significant modification of net primary productivity (NPP), soil respiration (Rs), net ecosystem production (NEP) and pools of tree biomass and soil ...

  18. Distribution and retention of cesium and strontium in Swedish boreal forest ecosystems

    International Nuclear Information System (INIS)

    The retention and distribution of cesium, and to some extent strontium, in forest environments are being studied at three sites in Sweden. The main part of the cesium found in the soil was recovered in horizons rich in organic matter. The cesium was retained in the soil organic matter in a more or less extractable form. As different soil types have a different distribution pattern of organic matter, the distribution of cesium will depend on the forest soil type. The clay content in Swedish forest soils is, in general, low which will mitigate the retention of cesium in the soil mineral horizons. The cesium and strontium present in the trees was considered to be an effect of assimilation by the tissues in the canopy as well as by the roots. The redistribution of cesium within the trees was extensive which was considered to be the effect of a high mobility of cesium in the trees. The recovery of strontium-90 in pines, in relation to the deposition rate was higher compared to the relative recovery of cesium-137, 30 years after deposition. The cesium and strontium will remain in the forest environment for a considerable time but can be reduced by forest practice, by leaching out of the soil profile or by radioactive decay

  19. Comparing soil biogeochemical processes in novel and natural boreal forest ecosystems

    OpenAIRE

    S. A. Quideau; M. J. B. Swallow; C. E. Prescott; S. J. Grayston; Oh, S.-W.

    2013-01-01

    Emulating the variability that exists in the natural landscape prior to disturbance should be a goal of soil reconstruction and land reclamation efforts following resource extraction. Long-term ecosystem sustainability within reclaimed landscapes can only be achieved with the re-establishment of biogeochemical processes between reconstructed soils and plants. In this study, we assessed key soil biogeochemical attributes (nutrient availability, organic matter composition, and...

  20. Comparing soil biogeochemical processes in novel and natural boreal forest ecosystems

    OpenAIRE

    S. A. Quideau; M. J. B. Swallow; C. E. Prescott; S. J. Grayston; S.-W. Oh

    2013-01-01

    Emulating the variability that exists in the natural landscape prior to disturbance should be a goal of soil reconstruction and land reclamation efforts following resource extraction. Long-term ecosystem sustainability within reclaimed landscapes can only be achieved with the re-establishment of biogeochemical processes between reconstructed soils and plants. In this study, we assessed key soil biogeochemical attributes (nutrient availability, organic matter composition, and microbial ...

  1. Thorium and uranium in soil fractions and certain macromycete species in boreal forest ecosystems

    Directory of Open Access Journals (Sweden)

    M. M. Vinichuk

    2012-07-01

    Full Text Available The content of thorium (Th and uranium (U in fractions of soil edaphosphere, rhizosphere, rhizoplane, fungal mycelium and fruit bodies were investigated. The concentrations of thorium in edaphosphere and rhizosphere fractions and mycelia of fungi are not different significantly and vary in the range of 0.74–1.45 mg kg–1 dry matter. The concentration of thorium in the rhizoplane fraction is 4 times lower than in the bulk soil – edaphosphere. The concentrations of uranium in edaphosphere, rhizosphere and rhizoplane fractions and fungi mycelium are not significantly different and vary between 3.11 and 9.36 mg kg–1 dry matter. The content of the studied natural isotopes in fruit bodies of fungi is 270 times lower than in the bulk soil: biological absorption coefficients of uranium and thorium in fruit bodies are on average 0.035 and 0.006, respectively. The contents of thorium and uranium in fungal mycelium and fruit bodies increase with increasing their concentrations in the soil. It is shown that in the fungi mycelium of the upper (0–5 cm layer of forest soil can be allocated 2.0–5.0 and 1.4–2.7 % of the total thorium and uranium soil content, respectively.

  2. Boreal forest CO2 exchange and evapotranspiration predicted by nine ecosystem process models: Intermodel comparisons and relationships to field measurements

    OpenAIRE

    Amthor, J. S.; J. M. Chen; Clein, J. S.; Frolking, S. E.; Goulden, M. L.; R. F. Grant; J. S. Kimball; A. W. King; Mcguire, A. D.; Nikolov, N. T.; Potter, C.S.; Wang, S.; Wofsy, S.C.

    2001-01-01

    Nine ecosystem process models were used to predict CO2 and water vapor exchanges by a 150-year-old black spruce forest in central Canada during 1994–1996 to evaluate and improve the models. Three models had hourly time steps, five had daily time steps, and one had monthly time steps. Model input included site ecosystem characteristics and meteorology. Model predictions were compared to eddy covariance (EC) measurements of whole-ecosystem CO2 exchange and evapotranspiration, to chamber measure...

  3. 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...

  4. Carbon Isotope Composition of Ecosystem Respired Carbon Dioxide in Three Boreal Forest Ecosystems: Measurements and Model Calculations

    Science.gov (United States)

    Cai, T.; Flanagan, L. B.

    2007-12-01

    We conducted measurements of seasonal and inter-annual variation in the carbon isotope composition of ecosystem respired CO2 (δR) in aspen, black spruce and jack pine dominated ecosystems in northern Saskatchewan during 2004-2006 as part of the Fluxnet-Canada Research Network. All three sites showed relatively small variation (approximately -26 to -29 per mil) in δR values during the entire study. The measurements were strongly correlated with modeled δ13C values of ecosystem respired CO2. The model calculated leaf CO2 assimilation, stomatal conductance and chloroplast CO2 concentration separately for sunlit and shaded leaves within multiple canopy layers, and, therefore, allowed us to estimate canopy photosynthetic 13C discrimination. All three sites showed variation in canopy 13C discrimination in response to environmental conditions in a manner consistent with well-known leaf-level studies. Specifically, 13C discrimination was positively correlated with soil moisture and negatively correlated with photon flux density, air temperature and vapor pressure deficit. As a consequence a strong diurnal pattern was observed for 13C discrimination. The measured δR values also varied in response to environmental conditions in a manner consistent with well-known leaf-level studies of photosynthetic 13C discrimination, but with a dampened response caused by the contribution of heterotrophic respiration, which had a constant δ13C value. These results indicate that the stable isotope composition of respired CO2 is a useful ecosystem-scale tool to study constraints to photosynthesis and acclimation of ecosystems to environmental stress.

  5. 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...

  6. 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).

  7. Manganese in the litter fall-forest floor continuum of boreal and temperate pine and spruce forest ecosystems

    DEFF Research Database (Denmark)

    Berg, Björn; Erhagen, Björn; Johansson, Maj-Britt;

    2015-01-01

    We have reviewed the literature on the role of manganese (Mn) in the litter fall-to-humus subsystem. Available data gives a focus on North European coniferous forests. Manganese concentrations in pine (Pinus spp.) foliar litter are highly variable both spatially and temporally within the same...... from pine needle litter significantly faster (p < 0.001) than that from the Mn-richer litter of Norway spruce. Over Northern Europe concentrations of total Mn in mor humus as well as extractable Mn in the mineral soil increase with decreasing MAT and over a climatic gradient the Mn concentrations in...... carbon (C) in mor layers under Norway spruce as compared to Scots pine as well as the higher amount of C in mineral soil under spruce. The increase in nitrogen (N) concentration in humus, following N fertilization resulted in a decrease in that of Mn. We have found four cases – empirical – with negative...

  8. Modeling Analysis of Primary Controls on Net Ecosystem Productivity of Seven Boreal and Temperate Coniferous Forests Across a Continental Transect

    OpenAIRE

    McCaughey, J. Harry; Margolis, Hank A; Coursolle, Carole; Bourque, Charles P. A.; Black, T. Andrew; Barr, Alan G.; Arain, M. Altaf; Yuan, Fengming; Wofsy, Steven C.

    2008-01-01

    Process-based models are effective tools to synthesize and/or extrapolate measured carbon (C) exchanges from individual sites to large scales. In this study, we used a C- and nitrogen (N)-cycle coupled ecosystem model named CN-CLASS (Carbon Nitrogen-Canadian Land Surface Scheme) to study the role of primary climatic controls and site-specific C stocks on the net ecosystem productivity (NEP) of seven intermediate-aged to mature coniferous forest sites across an east–west continental transect i...

  9. Browning boreal forests of western North America

    Science.gov (United States)

    Verbyla, David

    2011-12-01

    Forest Ecol. Manag. 227 219-32 Berg E E, Hillman K M, Dial R and DeRuwe A 2009 Recent woody invasion of wetlands on the Kenai Peninsula Lowlands, south-central Alaska: a major regime shift after 18 000 years of wet Sphagnum-sedge peat recruitment Canadian J. Forest Res. 39 2033-46 Brabets T P and Walvoord M A 2009 Trends in streamflow in the Yukon River Basin from 1944 to 2004 and the influence of the Pacific Decadal Oscillation J. Hydrol. 371 108-19 Bunn A G, Goetz S J, Kimball J S and Zhang K 2007 Northern high-latitude ecosystems respond to climate change EOS Trans. Am. Geophys. Union 88 333-40 D'Arrigo R, Kaufmann R K, Davi N, Jacoby G C, Laskowski C, Myneni R B and Cherubini P 2004 Thresholds for warming-induced growth decline at elevational tree line in the Yukon Territory, Canada Glob. Biogeochem. Cycles 18 GB3021 Goetz S J, Bunn A G, Fiske G J and Houghton R A 2005 Satellite-observed photosynthetic trends across boreal North America associated with climate and fire disturbance Proc. Natl Acad. Sci. USA 102 13521-5 Lloyd A H and Bunn A G 2007 Responses of the circumpolar boreal forest to the 20th century climate variability Environ. Res. Lett. 2 045013 Lloyd A H and Fastie C L 2002 Spatial and temporal variability in the growth and climate response of treeline trees in Alaska Clim. Change 52 481-509 Malmström C and Raffa K R 2000 Biotic disturbance agents in the boreal forest: considerations for vegetation change models Glob. Change Biol. 6 (Suppl. 1) 35-48 McGuire A D, Ruess R W, Lloyd A, Yarie J, Clein J S and Juday G P 2010 Vulnerability of white spruce tree growth in interior Alaska in response to climate variability: dendrochronological, demographic, and experimental perspectives Canadian J. Forest Res. 40 1197-209 Michealian M, Hogg E H, Hall R J and Arsenault E 2011 Massive mortality of aspen following severe drought along the southern edge of the Canadian boreal forest Glob. Change Biol. 17 2084-94 Parent M B and Verbyla D 2010 The browning of Alaska

  10. 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

  11. 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

  12. 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.

  13. Variability in Fire Frequency and Forest Composition in Canada's Southeastern Boreal Forest: A Challenge for Sustainable Forest Management

    OpenAIRE

    Mike Flannigan; Sylvie Gauthier; Christopher Carcaillet; Yves Bergeron; Pierre J.H. Richard; Prairie, Yves T.

    1998-01-01

    Because some consequences of fire resemble the effects of industrial forest harvesting, forest management is often considered as a disturbance having effects similar to those of natural disturbances. Although the analogy between forest management and fire disturbance in boreal ecosystems has some merit, it is important to recognize that it has limitations. First, normal forest rotations truncate the natural forest stand age distribution and eliminate over-mature forests from the landscape. Se...

  14. 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.

  15. 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...

  16. 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.

  17. 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...

  18. 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.

  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. Effects of acid precipitation on a boreal forest ecosystem. Ion budgets and changes in water chemistry for the Laflamme Lake watershed

    Energy Technology Data Exchange (ETDEWEB)

    Papineau, M.

    1987-01-01

    Data on surface waters have been gathered at the Laflamme Lake Watershed in Quebec as part of an ion budget research program. This watershed was set up in 1980 to assess the effects of long range transport of airborne pollutants on a boreal forest ecosystem receiving moderate to high sulphate loading. Precipitation data indicates that between 1981 and 1984, the average pH of water falling onto the watershed was 4.4, that precipitation quality is cyclic and that loading is episodic. The main components of precipitation on an equivalent basis are sulfate, hydrogen, nitrate and ammonium ions. ALthough the sulphate to nitrate ration is 2:1 on a yearly basis, nitrate ions are more important than sulphates in January. Since water and pollutants build up in the snowpack, spring melt is a critical period during which concentrations in surface waters and exports from the watershed are modifed for many parameters especially hydrogen and bicarbonate ions. Lake water quality is characteristic of lakes that are very sensitive to acidification. High sulfate values seem to indicate that the watershed has been affected by atmospheric loading. The average pH of the lake (6.4) indicates that the lake is not yet greatly acidified. Important buffering occurs in the soil and surficial deposits of the watershed. Stream water is slightly less mineralized, slightly more acidic and shows more pronounced changes in water quality than lake water. Over the last five years, sulfate, conductivity and some heavy metal levels have increased in surface waters while no significant trends were seen for pH and alkalinity. In other Quebec monitoring lakes, trends of decreasing pH were seen during this period. When wet loading is compared to stream output, hydrogen and nitrate ions are seen to be retained in the watershed while Ca, Mg, Na, K, sulphate and chloride are lost. 63 refs. 31 figs. 32 tabs.

  1. Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO2 efflux

    OpenAIRE

    S. M. Niinistö; Kellomäki, S.; J. Silvola

    2011-01-01

    Our objectives were to identify factors related to temporal variation of soil CO2 efflux in a boreal pine forest and to evaluate simple predictive models of temporal variation of soil CO2 efflux. Soil CO2 efflux was measured with a portable chamber in a Finnish Scots pine forest for three years, with a fourth year for model evaluation. Plot averages for soil CO2 efflux ranged from 0.04 to 0.90 g CO2 m−2 h−1 during the snow-free period, i.e. May–October, and from 0.04 to 0.13...

  2. Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO2 efflux

    OpenAIRE

    Kellomäki, S.; J. Silvola; S. M. Niinistö

    2011-01-01

    Our objectives were to identify factors related to temporal variation of soil CO2 efflux in a boreal pine forest and to evaluate simple predictive models of temporal variation of soil CO2 efflux. Soil CO2 efflux was measured with a portable chamber in a Finnish Scots pine forest for three years, with a fourth year for model evaluation. Plot averages for soil CO2 efflux ranged from 0.04 to 0.90 g CO2 m−2 h−1 during the snow-free period, i.e. May–October, and from 0.04 to 0.13 g CO2 m−2 h−1 in ...

  3. 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.

  4. Biogeochemistry in forest ecosystems

    OpenAIRE

    Saint-André, Laurent

    2014-01-01

    Scientific objectives : - Analyse biogeochemical cycles (major and micro-nutrients; stocks and fluxes, processes and driving parameters) in forest ecosystems - Formalise this knowledge into concepts and models to predict ecosystem modifications to environmental changes. - Human and social issues - Propose management rules to ensure the sustainability of forest ecosystems in a changing environment.

  5. Distribution of 210Pb and 210Po concentrations in wild berries and mushrooms in boreal forest ecosystems

    International Nuclear Information System (INIS)

    The activity concentrations and distribution of 210Pb and 210Po in wild berries and edible mushrooms were investigated in Finnish forests. The main study areas were located in Scots pine (Pinus sylvestris L.) forests in southern and northern Finland. The activity concentrations of 210Pb and 210Po in blueberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) samples decreased in the order: stems > leaves > berries (i.e. fruits). The activity ratios of 210Po/210Pb in the wild berry samples were mainly higher than one, indicating elevated activity concentrations of polonium in the samples. In mushrooms the activity concentrations of 210Pb and especially 210Po were higher than in fruits of the wild berries. The highest activity concentration of 210Pb was detected in Cortinarius armillatus L. (16.2 Bq kg-1 d.w.) and the lowest in Leccinum vulpinum L. (1.38 Bq kg-1 d.w.). The 210Po activity concentrations of the whole fruiting bodies ranged from 7.14 Bq kg-1 d.w. (Russula paludosa L.) to 1174 Bq kg-1 d.w. (L. vulpinum L.). In general, the highest activity concentrations of 210Po were recorded in boletes. The caps of mushrooms of the Boletaceae family showed higher activity concentrations of 210Po compared to the stipes. In most of the mushrooms analyzed, the activity concentrations of 210Po were higher than those of 210Pb. 210Po and 210Pb dominate the radiation doses received via ingestion of wild berries and mushrooms in northern Finland, while in southern Finland the ingested dose is dominated by 137Cs from the Chernobyl fallout.

  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. Variability in Fire Frequency and Forest Composition in Canada's Southeastern Boreal Forest: A Challenge for Sustainable Forest Management

    Directory of Open Access Journals (Sweden)

    Mike Flannigan

    1998-12-01

    Full Text Available Because some consequences of fire resemble the effects of industrial forest harvesting, forest management is often considered as a disturbance having effects similar to those of natural disturbances. Although the analogy between forest management and fire disturbance in boreal ecosystems has some merit, it is important to recognize that it has limitations. First, normal forest rotations truncate the natural forest stand age distribution and eliminate over-mature forests from the landscape. Second, in the boreal mixedwoods, natural forest dynamics following fire may involve a gradual replacement of stands of intolerant broadleaf species by mixedwood and then softwood stands, whereas current silvicultural practices promote successive rotations of similarly composed stands. Third, the large fluctuations observed in fire frequency during the Holocene limit the use of a single fire cycle to characterize natural fire regimes. Short fire cycles generally described for boreal ecosystems do not appear to be universal; rather, shifts between short and long fire cycles have been observed. These shifts imply important changes in forest composition at the landscape and regional levels. All of these factors create a natural variability in forest composition that should be maintained by forest managers concerned with the conservation of biodiversity. One avenue is to develop silvicultural techniques that maintain a spectrum of forest compositions over the landscape.

  8. 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...

  9. 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.

  10. 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.

  11. 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.

  12. Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO2 efflux

    Directory of Open Access Journals (Sweden)

    S. Kellomäki

    2011-11-01

    Full Text Available Our objectives were to identify factors related to temporal variation of soil CO2 efflux in a boreal pine forest and to evaluate simple predictive models of temporal variation of soil CO2 efflux. Soil CO2 efflux was measured with a portable chamber in a Finnish Scots pine forest for three years, with a fourth year for model evaluation. Plot averages for soil CO2 efflux ranged from 0.04 to 0.90 g CO2 m−2 h−1 during the snow-free period, i.e. May–October, and from 0.04 to 0.13 g CO2 m−2 h−1 in winter. Soil temperature was a good predictor of soil CO2 efflux. A quadratic model of ln-transformed efflux explained 76–82 % of the variation over the snow-free period. The results revealed an effect of season: at a given temperature of the organic layer, soil CO2 efflux was higher later in the snow-free period (in August and September than in spring and early summer (in May and June. Regression coefficients for temperature (approximations of a Q10 value of month-specific models decreased with increasing average soil temperatures. Efflux in July, the month of peak photosynthesis, showed no clear response to temperature or moisture. Inclusion of a seasonality index, degree days, improved the accuracy of temperature response models to predict efflux for the fourth year of measurements, which was not used in building of regression models. During peak efflux from mid-July to late-August, efflux was underestimated with the models that included degree days as well as with the models that did not. The strong influence of the flux of photosynthates belowground and the importance of root respiration could explain the relative temperature insensitivity observed in July and together with seasonality of growth of root and root-associated mycorrhizal fungi could explain partial failure of models to predict magnitude of efflux in the peak season from mid-July to August. The effect of moisture early in the season was confounded by simultaneous advancement of

  13. 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.

  14. 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.

  15. 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

  16. Adaptation of forest ecosystems, forests and forestry to climate change. FINADAPT Working Paper 4

    OpenAIRE

    KellomÀki, Seppo; Strandman, Harri; Nuutinen, Tuula; Peltola, Heli; Korhonen, Kari T.; VÀisÀnen, Hannu

    2005-01-01

    In this study, an ecosystem model (Sima), capable of predicting ecosystem level functioning of boreal forests, was used together with a permanent sample plot data of the Finnish national forest inventory (measured in 1995) and different climate scenarios to analyze, how increase in temperature, precipitation and atmospheric carbon dioxide concentration may effect forest growth and dynamics in Finnish conditions. The simulations showed that the forest ecosystems are most impacted in the most n...

  17. 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.

  18. 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...

  19. Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO2 efflux

    Directory of Open Access Journals (Sweden)

    S. Kellomäki

    2011-03-01

    Full Text Available Our objectives were to identify factors related to temporal variation of soil CO2 efflux in a boreal pine forest and to evaluate simple predictive models of temporal variation of soil CO2 efflux. Soil CO2 efflux was measured with a portable chamber in a Finnish Scots pine forest for three years, with a fourth year for model evaluation. Plot averages for soil CO2 efflux ranged from 0.04 to 0.90 g CO2 m−2 h−1 during the snow-free period, i.e. May–October, and from 0.04 to 0.13 g CO2 m−2 h−1 in winter. Soil temperature was a good predictor of soil CO2 efflux. A quadratic model of ln-transformed efflux explained 76–82% of the variation over the snow-free period. The results revealed strong seasonality: at a given soil temperature, soil CO2 efflux was higher later in the snow-free period than in spring and early summer. Regression coefficients for temperature (approximations of a Q10 value of month-specific models decreased with increasing average soil temperatures. Efflux in July, the month of peak photosynthesis, showed no clear response to temperature or moisture. Inclusion of a seasonality index, degree days, improved the accuracy of temperature response models to predict efflux for the fourth year of measurements, which was not used in building of regression models. Underestimation during peak efflux (mid-July to late-August remained uncorrected. The strong influence of the flux of photosynthates belowground and the importance of root respiration could explain the relative temperature insensitivity observed in July and together with seasonality of growth of root and root-associated mycorrhizal fungi could explain partial failure of models to predict magnitude of efflux in the peak season from mid-July to August. The effect of moisture early in the season was confounded by simultaneous advancement of the growing season and increase in temperature. In a dry year, however, the effect of drought was evident as soil CO2 efflux was some 30

  20. 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.

  1. Patchwork policy, fragmented forests: In-situ oil sands, industrial development, and the ecological integrity of Alberta's boreal forest

    International Nuclear Information System (INIS)

    Environmental impacts of current oil sands industry activities and the potential cumulative impacts of new in-situ oil sands development on the boreal forest of northeastern Alberta are reviewed. The objective is to improve understanding of the impacts of existing industrial activity on the broader boreal forest ecosystem, and the environmental implications of further disturbance to this ecosystem from future development of heavy and conventional fossil fuel reserves in the province. The report also outlines elements of a boreal forest use framework that could assist in managing industrial activity within ecologically sustainable limits and makes recommendations for specific actions that need to be taken by government and industry to guide future development decisions. The top 50 key landscape areas of interest in the province, identified by the World Wildlife Federation, based primarily on a series of reports by Alberta Environmental Protection, are briefly described. Implications of failure to act are also outlined. 138 end-notes, 8 tabs., 16 figs

  2. 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.

  3. 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

  4. 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

  5. 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....

  6. Responses of aboveground and belowground forest carbon stocks to disturbances in boreal forests of Northeastern China

    Science.gov (United States)

    Huang, Chao; He, Hong S.; Hawbaker, Todd J.; Liang, Yu; Gong, Peng; Wu, Wuzhiwei; Zhu, Zhiliang

    2016-04-01

    Boreal forests represents about 1/3 of forest area and 1/3 of forest carbon on earth. Carbon dynamics of boreal forests are sensitive to climate change, natural (e.g., fire) and anthropogenic (e.g., harvest) disturbances. Field-based studies suggest that disturbances alter species composition, stand structure, and litter decomposition, and have significant effects on boreal forest carbon dynamics. Most of these studies, however, covered a relatively short period of time (e.g., few decades), which is limited in revealing such long-term effects of disturbances. Models are therefore developed as important tools in exploring the long-term (e.g., hundreds of years) effects of disturbances on forest carbon dynamics. In this study, we applied a framework of coupling forest ecosystem and landscape model to evaluating the effect of fire, harvest and their interactions on carbon stocks in a boreal forest landscape of Northeastern China. We compared the simulation results under fire, harvest and fire-harvest interaction scenarios with the simulated value of succession scenario at 26 landtypes over 150 years at a 10-year time step. Our results suggest that aboveground and belowground carbon are significantly reduced by fire and harvest over 150years. Fire reduced aboveground carbon by 2.3±0.6 ton/ha, harvest by 6.0±1.4 ton/ha, and fire and harvest interaction by 8.0±1.9 tons/ha. Fire reduced belowground carbon by 4.6±3.4 ton/ha, harvest by 5.0±3.5 ton/ha, and fire-harvest interaction by 5.7±3.7 tons/ha. The divergent response of carbon stocks among landtypes and between disturbance scenarios was due to the spatial interactions between fire, harvest, and species composition. Our results indicated that boreal forests carbon stocks prediction needs to consider the effects of fire and harvest for improving the estimation accuracy.

  7. USDA forest service global change research: Monitored ecosystems, northern linkages

    International Nuclear Information System (INIS)

    Foresters and natural resource managers have traditionally based long-term plans (i.e., 100+ year harvest cycles) on the assumption of stable landscapes and climate. Global climate change undercuts these assumptions and may alter or invalidate some accepted natural resource management practices and paradigms. Possible changes in biomass productivity, shifting of forest species' latitudinal or elevational limits, and rapid changes in forest community species and age class composition, all have major implications for management of the nation's forests. The USDA Forest Service is undertaking a national research program to assess rates, significant processes, and management implications of possible climatic change for the nation's forests and related resources. Pacific Region Forest Service global change research places major emphasis on understanding and monitoring forest processes in the northern boreal forest and the sub-arctic taiga of Alaska, which is potentially sensitive to climatic warming and to shifts in precipitation regime. A major terrestrial carbon pool, taiga forests and organic soils may also be important in the flux of greenhouse gases between landscape and atmosphere. Forest Service research emphasizes an ecosystem approach, incorporating landscape- and watershed-level field research with smaller-scale studies of forest ecosystem response mechanisms. Ecological monitoring is critical, and includes establishment of a monitoring mega-transect from northern latitudinal tree line to mediterranean/dry temperate forest/shrublands. Emphasis is placed on the most critical Pacific Region ecosystems: northern boreal forest (taiga), moist temperate forest, and mediterranean/dry temperate forest (chaparral/southern Ponderosa pine)

  8. Predicting Forest Floor Consumption From Wildland Fire in Boreal forests of Alaska

    Science.gov (United States)

    Ottmar, R. D.

    2010-12-01

    Forest fires are one of the dominant ecological force shaping the distribution and structure of boreal ecosystems. Many areas of the boreal forests of Alaska often contain deep layers of moss, duff, and peat, resulting in large pools of sequestered carbon and biomass that potentially can burn and smolder for long periods of time during these wildfires creating hazardous smoke episodes for local residents and communities and causing detrimental landscape impacts. Research to quantify forest floor consumption is critical for effective modeling fire effects such as smoke emissions, regional haze, global warming, permafrost melting, erosion, and plant succession. Forest floor reduction was measured at 18 black and white spruce and birch-aspen prescribed fires between 1990-2004 and 24 black and white spruce sites on 6 wildfires during 2003 and 2004. Three of the sites were part of the large international Frostfire project near Fairbanks, Alaska, and were used as an independent test data set. Several forest floor reduction equations were developed, of which one is presented in this presentation. The double parameter equation uses upper forest floor fuel moisture content and preburn forest floor depth as independent variables. The fuel moisture content of the upper forest floor can be obtained from forest floor samples that are collected, oven dried, and weighed to determine gravimetric fuel moisture content. The preburn forest floor depths require onsite measurements to be collected. The forest floor consumption model has been incorporated into Consume, a software package used by land managers and scientists to predict fuel consumption during wildland fires.

  9. 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...

  10. Long-term effects of single potassium fertilization on 137Cs levels in plants and fungi in a boreal forest ecosystem

    International Nuclear Information System (INIS)

    We examined the long-term effects of a single application of potassium (K) fertilizer (100 kg K ha-1) in 1992 on 137Cs uptake in a forest ecosystem in central Sweden. 137Cs activity concentrations were determined in three low-growing perennial shrubs, heather (Calluna vulgaris), lingonberry (Vaccinium vitis-idaea) and bilberry (Vaccinium myrtillus), and in four wild fungal species (Cortinarius semisanguineus, Lactarius rufus, Rozites caperata and Suillus variegatus). Uptake of 137Cs by plants and fungi growing on K-fertilized plots 17 years after application of the K fertilizer was significantly lower than in corresponding species growing in a non-fertilized control area. The 137Cs activity concentration was 21-58% lower in fungal sporocarps and 40-61% lower in plants in the K-fertilized area compared with the control. Over the study period, this decrease in 137Cs activity concentration was more consistent in plants than in fungi, although the effect was statistically significant and strongly pronounced in all species. The effect of K fertilization in reducing 137Cs activity concentration in fungi and plants decreased over time but was still significant in 2009, 17 years after fertilization. This suggests that application of K fertilizer to forests is an appropriate and effective long-term measure to decrease radiocaesium accumulation in plants and fungi. - Research highlights: → Effects of potassium fertilizer on 137Cs uptake by plants and fungi are investigated. → 137Cs activity concentrations in forest plants decreased even within the first year. → The most significant reduction occurred over the first 7-8 years. → The reduction in fungi was less pronounced, but still statistically significant.

  11. 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

  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. 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

  14. Ectomycorrhizal-Dominated Boreal and Tropical Forests Have Distinct Fungal Communities, but Analogous Spatial Patterns across Soil Horizons

    OpenAIRE

    McGuire, Krista L.; Allison, Steven D.; Fierer, Noah; Treseder, Kathleen K.

    2013-01-01

    Fungi regulate key nutrient cycling processes in many forest ecosystems, but their diversity and distribution within and across ecosystems are poorly understood. Here, we examine the spatial distribution of fungi across a boreal and tropical ecosystem, focusing on ectomycorrhizal fungi. We analyzed fungal community composition across litter (organic horizons) and underlying soil horizons (0–20 cm) using 454 pyrosequencing and clone library sequencing. In both forests, we found significant clu...

  15. 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.

  16. 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...

  17. Thermokarst rates intensify due to climate change and forest fragmentation in an Alaskan boreal forest lowland.

    Science.gov (United States)

    Lara, Mark J; Genet, Hélène; McGuire, Anthony D; Euskirchen, Eugénie S; Zhang, Yujin; Brown, Dana R N; Jorgenson, Mark T; Romanovsky, Vladimir; Breen, Amy; Bolton, William R

    2016-02-01

    Lowland boreal forest ecosystems in Alaska are dominated by wetlands comprised of a complex mosaic of fens, collapse-scar bogs, low shrub/scrub, and forests growing on elevated ice-rich permafrost soils. Thermokarst has affected the lowlands of the Tanana Flats in central Alaska for centuries, as thawing permafrost collapses forests that transition to wetlands. Located within the discontinuous permafrost zone, this region has significantly warmed over the past half-century, and much of these carbon-rich permafrost soils are now within ~0.5 °C of thawing. Increased permafrost thaw in lowland boreal forests in response to warming may have consequences for the climate system. This study evaluates the trajectories and potential drivers of 60 years of forest change in a landscape subjected to permafrost thaw in unburned dominant forest types (paper birch and black spruce) associated with location on elevated permafrost plateau and across multiple time periods (1949, 1978, 1986, 1998, and 2009) using historical and contemporary aerial and satellite images for change detection. We developed (i) a deterministic statistical model to evaluate the potential climatic controls on forest change using gradient boosting and regression tree analysis, and (ii) a 30 × 30 m land cover map of the Tanana Flats to estimate the potential landscape-level losses of forest area due to thermokarst from 1949 to 2009. Over the 60-year period, we observed a nonlinear loss of birch forests and a relatively continuous gain of spruce forest associated with thermokarst and forest succession, while gradient boosting/regression tree models identify precipitation and forest fragmentation as the primary factors controlling birch and spruce forest change, respectively. Between 1950 and 2009, landscape-level analysis estimates a transition of ~15 km² or ~7% of birch forests to wetlands, where the greatest change followed warm periods. This work highlights that the vulnerability and resilience of

  18. Radionuclides in forest ecosystems

    International Nuclear Information System (INIS)

    Some regions within Austria were highly contaminated (> 50 kBq m-2) with radiocaesium by the deposition event following the Chernobyl reactor accident in 1986. Monitoring carried out by several Austrian institutions showed that in contrast to agricultural products radiocaesium levels in wild berries, mushrooms and game meat from forest ecosystems remained considerably higher over the years. To find reasons for this contrasting radioecological behavior and for the derivation of model input parameters, an extended study about the distribution of 137Cs within three Austrian forest stands was carried out between 1987 and 1997. Results of this and subsequent studies are summarized and include the following ecosystem compartments: forest soils, litter, trees, bilberry, mushrooms, mosses, ferns, lichen, other vegetation, insects, small mammals, game animals and surface water. Besides the investigation of radioecological behavior an estimation of pool sizes and transfer rates as well as radioecological residence half times for 137Cs in different forest species was used to compile a radiocaesium balance for the years 1988 and 1996. Soil proved to be an effective sink for radiocaesium contamination, but in long-term perspective it can act as a source for the contamination of vegetation and higher levels of the food-chain as well. Due to the high standing biomass trees represent the largest 'living' radiocaesium pool within the investigated forest stand. Dose estimations based on average consume habits gave no significant increase (less than 0.4 %) of the annual average population radiation dose due to the ingestion of forest products from the investigated forest stands. (author)

  19. 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.

  20. 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.

  1. 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....

  2. Spatially explicit fire-climate history of the boreal forest-tundra (Eastern Canada) over the last 2000 years

    OpenAIRE

    Payette, Serge; Filion, Louise; Delwaide, Ann

    2007-01-01

    Across the boreal forest, fire is the main disturbance factor and driver of ecosystem changes. In this study, we reconstructed a long-term, spatially explicit fire history of a forest-tundra region in northeastern Canada. We hypothesized that current occupation of similar topographic and edaphic sites by tundra and forest was the consequence of cumulative regression with time of forest cover due to compounding fire and climate disturbances. All fires were mapped and dated per 100 year interva...

  3. 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.

  4. 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.

  5. 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

  6. 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)

  7. 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

  8. Pinus sylvestris as a missing source of nitrous oxide and methane in boreal forest

    OpenAIRE

    Katerina Machacova; Jaana Bäck; Anni Vanhatalo; Elisa Halmeenmäki; Pasi Kolari; Ivan Mammarella; Jukka Pumpanen; Manuel Acosta; Otmar Urban; Mari Pihlatie

    2016-01-01

    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...

  9. 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...

  10. 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. ...

  11. 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.

  12. 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.

  13. The climate responses of tropical and boreal ecosystems with an improved land surface model (JULES)

    Science.gov (United States)

    Harper, Anna; Friedlingstein, Pierre; Cox, Peter; Wiltshire, Andy; Jones, Chris

    2016-04-01

    The Joint UK Land Environment Simulator (JULES) is the land surface of the next generation UK Earth System Model (UKESM1). Recently, JULES was updated with new plant functional types and physiology based on a global plant trait database. These developments improved the simulation of terrestrial gross and net primary productivity on local and global scales, and enabled a more realistic representation of the global distribution of vegetation. In this study, we explore the present-day distribution of ecosystems and their vulnerability to climate change in JULES with these improvements, focusing on tropical and boreal ecosystems. Changes to these ecosystems will have implications for biogeophysical and biogeochemical feedbacks to climate change and need to be understood. First, we examine the simulated and observed rainforest-savannah boundary, which is strongly related to annual precipitation and the maximum climatological water deficit. Second, we assess the length of growing season and biomass stored in boreal ecosystems, where 20th century warming has likely extended the growing season. In each case, we first evaluate the ability of JULES to capture observed climate-vegetation relationships and trends. Finally, we run JULES to 2100 using climate data from 3 models and 2 RCP scenarios, and examine potential 21st century changes to these ecosystems. For example, do the tropical forests shrink in response to changes in tropical rainfall seasonality? And, how does the composition of boreal ecosystems change in response to climate warming? Given the potential for climate feedbacks and the inherent value in these ecosystems, it is essential to assess their responses to a range of climate change scenarios.

  14. 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...

  15. 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...

  16. 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.

  17. 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.

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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.

  3. 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)

  4. Changing sources and sinks of carbon in boreal ecosystems of Interior Alaska: Current and future perspectives

    Science.gov (United States)

    Douglas, T. A.; Jones, M.; Hiemstra, C. A.

    2012-12-01

    Future climate scenarios predict a roughly 5°C increase in mean annual air temperatures for the Alaskan Interior over the next 80 years. Increasing temperatures and greater frequency and severity of climate-induced disturbances such as wildfires will be enough to initiate permafrost degradation in many areas of Alaska, leading to major changes in surface hydrology and ecosystem structure and function. This, in turn, is expected to alter the current inventories of carbon sources and sinks in the region and provide a management challenge for carbon itemization efforts. To assist land managers in adapting and planning for potential changes in Interior Alaska carbon cycling we synthesize information on climate, ecosystem processes, vegetation, and soil, permafrost, and hydrologic regimes in Interior Alaska. Our goal is to provide an assessment of the current and likely future regime of Interior Alaska carbon sources and sinks. For our carbon assessment we: 1) synthesize the most recent results from numerous studies on the carbon cycle with a focus on research from the Alaskan boreal biome, 2) assemble a summary of estimates of carbon sources in soil and vegetation in Interior Alaska, 3) categorize carbon sources and sinks for predominant Interior Alaska ecosystems, and 4) identify expected changes in sources and sinks with climate change and human activities. This information is used to provide recommendations on potential actions land managers can take to minimize carbon export from the boreal forest. Though the results from our project are geared primarily toward policy makers and land managers we also provide recommendations for filling research gaps that currently present uncertainty in our understanding of the carbon cycle in boreal forest ecosystems of Interior Alaska.

  5. 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

  6. 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.

  7. Ca isotope cycling in a forested ecosystem

    Science.gov (United States)

    Holmden, Chris; Bélanger, Nicolas

    2010-02-01

    Reports of large Ca isotope fractionations between trees and soils prompted this study of a Boreal forest ecosystem near La Ronge, Saskatchewan, to improve understanding of this phenomenon. The results on five tree species (black spruce, trembling aspen, white spruce, jack pine, balsam poplar) confirm that nutrient Ca uptake by plants favors the light isotopes, thus driving residual Ca in plant available soil pools towards enrichment in the heavy isotopes. Substantial within-tree fraction occurs in tissues formed along the transpiration stream, with low δ 44Ca values in fine roots (2 mm), intermediate values in stemwood, and high values in foliage. Separation factors between different plant tissues are similar between species, but the initial fractionation step in the tips of the fine roots is species specific, and/or sensitive to the local soil environment. Soil water δ 44Ca values appear to increase with depth to at least 35 cm below the top of the forest floor, which is close to the deepest level of fine roots. The heavy plant fractionated signature of Ca in the finely rooted upper soils filters downward where it is retained on ion exchange sites, leached into groundwater, and discharged into surface waters. The relationship between Ca uptake by tree fine roots and the pattern of δ 44Ca enrichment with soil depth was modeled for two Ca pools: the forest floor (litter) and the underlying (upper B) mineral soil. Six study plots were investigated along two hillside toposequences trending upwards from a first order stream. We used allometric equations describing the Ca distribution in boreal tree species to calculate weighted average δ 44Ca values for the stands in each plot and estimate Ca uptake rates. The δ 44Ca value of precipitation was measured, and soil weathering signatures deduced, by acid leaching of lower B mineral soils. Steady state equations were used to derive a set of model Ca fluxes and fractionation factors for each plot. The model reproduces

  8. Fungal Community Shifts in Structure and Function across a Boreal Forest Fire Chronosequence.

    Science.gov (United States)

    Sun, Hui; Santalahti, Minna; Pumpanen, Jukka; Köster, Kajar; Berninger, Frank; Raffaello, Tommaso; Jumpponen, Ari; Asiegbu, Fred O; Heinonsalo, Jussi

    2015-11-01

    Forest fires are a common natural disturbance in forested ecosystems and have a large impact on the microbial communities in forest soils. The response of soil fungal communities to forest fire is poorly documented. Here, we investigated fungal community structure and function across a 152-year boreal forest fire chronosequence using high-throughput sequencing of the internal transcribed spacer 2 (ITS2) region and a functional gene array (GeoChip). Our results demonstrate that the boreal forest soil fungal community was most diverse soon after a fire disturbance and declined over time. The differences in the fungal communities were explained by changes in the abundance of basidiomycetes and ascomycetes. Ectomycorrhizal (ECM) fungi contributed to the increase in basidiomycete abundance over time, with the operational taxonomic units (OTUs) representing the genera Cortinarius and Piloderma dominating in abundance. Hierarchical cluster analysis by using gene signal intensity revealed that the sites with different fire histories formed separate clusters, suggesting differences in the potential to maintain essential biogeochemical soil processes. The site with the greatest biological diversity had also the most diverse genes. The genes involved in organic matter degradation in the mature forest, in which ECM fungi were the most abundant, were as common in the youngest site, in which saprotrophic fungi had a relatively higher abundance. This study provides insight into the impact of fire disturbance on soil fungal community dynamics. PMID:26341215

  9. 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.

  10. On forest ecosystem health and its Connotations

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper cursorily introduced some ideas and approaches of ecosystem health researches. The definition and connotations of forest ecosystem health have also been expatiated. Defining forest ecosystem health has been discussed from the management objective approach, ecosystem approach, and integration approach. To impel the relative researches in China, more attention on the properties of a forest ecosystem should be paid.

  11. The Boreal Ecosystem Research and Monitoring Sites (BERMS): A Canadian Contribution to CEOP

    Science.gov (United States)

    Barr, A. G.; Goodison, B.; Crawford, B.

    2004-05-01

    The Boreal Ecosystem Research and Monitoring Sites (BERMS) program is providing the Canadian contribution to the WCRP Coordinated Enhanced Observing Period (CEOP) initiative of the Global Energy and Water Experiment. The BERMS super-site, which is located at the southern edge of the boreal forest in central Saskatchewan Canada, currently operates ten flux towers in a variety of ecosystems in a study area of 120 x 100 km. These sites were originally established to study the energy, water and carbon cycles of the Canadian boreal forest in relation to inter-annual climate variability for different ecosystems. The area has also been used as a super-site for developing and validating remotely-sensed information and products, especially for snow cover. It was the site of a major validation effort for snow-water equivalent determination for AMSR-E. The sites are the flagship sites in Canada for studying the energy, water and carbon cycles in a cold-climate region and are well suited to the CEOP investigation. Five of the tower flux sites were first established in 1993-4 as part of the Boreal Ecosystem-Atmosphere Study (BOREAS) and have continued since 1997 as part of the BERMS program. Five additional sites have been recently established in young forest stands following disturbance by fire and harvest, with particular focus on the carbon cycle. The data from the three mature, long-term sites in Aspen, Black Spruce and Jack Pine have been submitted to CEOP. The BERMS program has served as a model for the Canadian field flux program of network-wide standardization in instrumentation and data post-processing, data management, and government-university collaboration. The modern, automated data management system has allowed provision of data for CEOP studies in a timely manner and within the CEOP data policy and guidelines. This presentation will provide an overview of the BERMS program and related remote sensing studies as they relate to CEOP, with particular focus on data

  12. Challenges in Modeling Disturbance Regimes and Their Impacts in Arctic and Boreal Ecosystems (Invited)

    Science.gov (United States)

    McGuire, A. D.; Rupp, T. S.; Kurz, W.

    2013-12-01

    Disturbances in arctic and boreal terrestrial ecosystems influence services provided by these ecosystems to society. In particular, changes in disturbance regimes in northern latitudes have uncertain consequences for the climate system. A major challenge for the scientific community is to develop the capability to predict how the frequency, severity and resultant impacts of disturbance regimes will change in response to future changes in climate projected for northern high latitudes. Here we compare what is known about drivers and impacts of wildfire, phytophagous insect pests, and thermokarst disturbance to illustrate the complexities in predicting future changes in disturbance regimes and their impacts in arctic and boreal regions. Much of the research on predicting fire has relied on the use of drivers related to fire weather. However, changes in vegetation, such as increases in broadleaf species, associated with intensified fire regimes have the potential to influence future fire regimes through negative feedbacks associated with reduced flammability. Phytophagous insect outbreaks have affected substantial portions of the boreal region in the past, but frequently the range of the tree host is larger than the range of the insect. There is evidence that a number of insect species are expanding their range in response to climate change. Major challenges to predicting outbreaks of phytophagous insects include modeling the effects of climate change on insect growth and maturation, winter mortality, plant host health, the synchrony of insect life stages and plant host phenology, and changes in the ranges of insect pests. Moreover, Earth System Models often simplify the representation of vegetation characteristics, e.g. the use of plant functional types, providing insufficient detail to link to insect population models. Thermokarst disturbance occurs when the thawing of ice-rich permafrost results in substantial ground subsidence. In the boreal forest, thermokarst can

  13. 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

  14. 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.

  15. Large-scale variation in boreal and temperate forest carbon turnover rate related to climate

    Science.gov (United States)

    Thurner, Martin; Beer, Christian; Carvalhais, Nuno; Forkel, Matthias; Santoro, Maurizio; Tum, Markus; Schmullius, Christiane

    2016-05-01

    Vegetation carbon turnover processes in forest ecosystems and their dominant drivers are far from being understood at a broader scale. Many of these turnover processes act on long timescales and include a lateral dimension and thus can hardly be investigated by plot-level studies alone. Making use of remote sensing-based products of net primary production (NPP) and biomass, here we show that spatial gradients of carbon turnover rate (k) in Northern Hemisphere boreal and temperate forests are explained by different climate-related processes depending on the ecosystem. k is related to frost damage effects and the trade-off between growth and frost adaptation in boreal forests, while drought stress and climate effects on insects and pathogens can explain an elevated k in temperate forests. By identifying relevant processes underlying broadscale patterns in k, we provide the basis for a detailed exploration of these mechanisms in field studies, and ultimately the improvement of their representations in global vegetation models (GVMs).

  16. 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.

  17. 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.

  18. 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...

  19. Site carbon storage along productivity gradients of a late-seral southern Boreal forest

    Energy Technology Data Exchange (ETDEWEB)

    Kranabetter, J.M. [British Columbia Ministry of Forests and Range, Victoria, BC (Canada)

    2009-05-15

    This study examined the total ecosystem carbon (TEC) range of late-seral southern Boreal forests that encompassed a typical gradient of upland plant communities and soils. Stand ages were approximately 180 years old. The study examined major pools of ecosystem carbon (C) effected by timber harvesting for use in forest management C accounting. C content was determined using a combination of direct measures and key parameter estimates of tree biomass, soil bulk density, and specific gravity of decayed wood. The aim of the study was to refine estimates for TEC as a function of plant association and indices of site productivity. The study was also conducted to obtain baseline data on the theoretical upper bounds of C pools among soil and organic horizons, coarse woody debris, and tree biomass in late-seral boreal stands. Soil, coarse woody debris, and forest biomass parameters were compared among plant associations in a randomized incomplete block design. The study showed that TEC was lowest on dry, poor-Cladonia sites and highest on subhydric, very rich-Devil's club sites. It was concluded that while C inventories based on zonal sites may be useful for developing broad estimates of TEC, they are likely to be inaccurate for detailed landscape analyses. 50 refs., 4 tabs., 2 figs.

  20. 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

  1. Reconciling Harvest Intensity and Plant Diversity in Boreal Ecosystems: Does Intensification Influence Understory Plant Diversity?

    Science.gov (United States)

    Kershaw, H Maureen; Morris, Dave M; Fleming, Robert L; Luckai, Nancy J

    2015-11-01

    Overall demand for forest products in the boreal forest is increasing to supply growing bio-energy demands in addition to traditional forest products. As a result, there is a need to refine current forest policies to reconcile production and ecosystem function within the context of ecologically sustainable management. This study assessed understory plants' richness, evenness, and diversity in six harvested boreal black spruce-dominated stands situated on loam, sand, and peat site types 15 years after the application of four harvest treatments of increasing biomass removals. Treatments included uncut, stem-only harvest, full-tree harvest, and full-tree harvest + blading of O horizon. Following canopy removal, species richness and diversity (Shannon's and Simpson's indices) increased on all soil types. The more than doubling of slash loading on the stem-only treatment plots compared to the full-tree plots led to significantly lower species diversity on loam sites; however, the reverse was observed on peat sites where the slash provided warmer, drier microsites facilitating the establishment of a broader array of species. Preexisting ericaceous shrub and sphagnum components continued to dominate on the peat sites. Compositional shifts were most evident for the full-tree + bladed treatment on all soil types, with increases in herbaceous cover including ruderal species. The results suggest that the intensification of harvesting on plant diversity varies with soil type, and these differential results should be considered in the refinement of forest biomass-harvesting guidelines to ensure ecological sustainability and biodiversity conservation over a broad suite of soil types. PMID:26092048

  2. Reconciling Harvest Intensity and Plant Diversity in Boreal Ecosystems: Does Intensification Influence Understory Plant Diversity?

    Science.gov (United States)

    Kershaw, H. Maureen; Morris, Dave M.; Fleming, Robert L.; Luckai, Nancy J.

    2015-11-01

    Overall demand for forest products in the boreal forest is increasing to supply growing bio-energy demands in addition to traditional forest products. As a result, there is a need to refine current forest policies to reconcile production and ecosystem function within the context of ecologically sustainable management. This study assessed understory plants' richness, evenness, and diversity in six harvested boreal black spruce-dominated stands situated on loam, sand, and peat site types 15 years after the application of four harvest treatments of increasing biomass removals. Treatments included uncut, stem-only harvest, full-tree harvest, and full-tree harvest + blading of O horizon. Following canopy removal, species richness and diversity (Shannon's and Simpson's indices) increased on all soil types. The more than doubling of slash loading on the stem-only treatment plots compared to the full-tree plots led to significantly lower species diversity on loam sites; however, the reverse was observed on peat sites where the slash provided warmer, drier microsites facilitating the establishment of a broader array of species. Preexisting ericaceous shrub and sphagnum components continued to dominate on the peat sites. Compositional shifts were most evident for the full-tree + bladed treatment on all soil types, with increases in herbaceous cover including ruderal species. The results suggest that the intensification of harvesting on plant diversity varies with soil type, and these differential results should be considered in the refinement of forest biomass-harvesting guidelines to ensure ecological sustainability and biodiversity conservation over a broad suite of soil types.

  3. Managing a boreal forest landscape for providing timber, storing and sequestering carbon

    DEFF Research Database (Denmark)

    Triviño, María; Juutinen, Artti; Mazziotta, Adriano; Miettinen, Kaisa; Podkopaev, Dmitry; Reunanen, Pasi; Mönkkönen, Mikko

    -offs between a provisioning (revenues from timber selling) and regulating (carbon storage and sequestration) ecosystem services among seven alternative forest management regimes in a large boreal forest production landscape. First, we estimate the potential of the landscape to produce harvest revenues and...... store/sequester carbon across a 50-year time period. Then, we identify conflicts between harvest revenues and carbon storage and sequestration. Finally, we apply multiobjective optimization to find optimal combinations of forest management regimes that maximize harvest revenues and carbon storage....../sequestration. Our results show that no management regime alone is able to either maximize harvest revenues or carbon services and that a combination of different regimes is needed. We also show that with a relatively little economic investment (5% decrease in harvest revenues), a substantial increase in carbon...

  4. Models parameterization for SWE retrievals from passive microwave over Canadian boreal forest

    Science.gov (United States)

    Roy, A.; Royer, A.; Langlois, A.; Montpetit, B.

    2012-12-01

    Boreal forest is the world largest northern land biome and has important impact and feedback on climate. Snow in this ecosystem changed drastically surface energy balance (albedo, turbulent fluxes). Furthermore, snow is a freshwater reservoir influencing hydrological regime and is an important source of energy through hydroelectricity. Passive microwave remote sensing is an appealing approach for characterizing the properties of snow at the synoptic scale; images are available at least twice a day for northern regions where meteorological stations and networks are generally sparse. However, major challenge such as forest canopy contribution and snow grain size within the snowpack, which have both huge impact on passive microwave signature from space-born sensors, must be well parameterized to retrieve variables of interest like Snow water equivalent (SWE). In this presentation, we show advances made in boreal forest τ-ω (forest transmissivity and scattering) and QH (soil reflectivity) models parameterization, as well as snow grains consideration development in the microwave snow emission. In the perspective of AMSR-E brightness temperature (Tb) assimilation in the Canadian Land surface scheme (CLASS), we used a new version of a multi-layer snow emission model: DMRT-ML. First, based on two distinct Tb datasets (winter airborne and summer space-borne), τ-ω and QH models are parameterized at 4 frequencies (6.9, 10.7, 18.7 and 36.5 GHz) for dense boreal forest sites. The forest transmissivity is then spatialized by establishing a relationship with forest structure parameters (LAI and stem volume). Secondly, snow surface specific area (SSA) was parameterized in DMRT-ML based on SWIR reflectance measurements for SSA calculation, as well as snow characteristics (temperature, density, height) and radiometric (19 & 37 GHz) measurements conducted on 20 snowpits in different open environments (grass, tundra, dry fen). Analysis shows that a correction factor must be

  5. 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

  6. Timing of plant phenophases since 1752 in the boreal forest environment

    Science.gov (United States)

    Kubin, Eero; Tolvanen, Anne; Karhu, Jouni; Valkama, Jari

    2016-04-01

    almost constant in the southern boreal zone. Effective temperature sum is important for the timing of the bud burst. The timing of phenological phenomena of forest vegetation, berry and seed crops reflects information about the response of the forest environment to the changes in the environmental factors. The global warming will be at its most powerful in the northern latitudes and this phenomenon is predicted to become increasingly more powerful in the future. Study of the regional differences will yield information about the changes in the northern limits of distribution of different plant species, and these changes can significantly affect the quantitative proportions of plant species. These changes, in turn, have an indirect impact on the entire ecosystem and the sources of livelihood relying on it. Phenological monitoring is nowadays more important than ever especially in boreal regions, where spring temperatures are elevated. Compilation and documentation of observations on plant phenophases play a key role in working out the rate of global climate change. To utilize citizen-science data together with the scientific monitoring will be discussed in the conference.

  7. Retrieval of seasonal dynamics of forest understory reflectance from semi-arid to boreal forests using MODIS BRDF data

    Science.gov (United States)

    Pisek, Jan; Chen, Jing; Kobayashi, Hideki; Rautiainen, Miina; Schaepman, Michael; Karnieli, Arnon; Sprintsin, Michael; Ryu, Youngryel; Nikopensius, Maris; Raabe, Kairi

    2016-04-01

    Ground vegetation (understory) provides an essential contribution to the whole-stand reflectance signal in many boreal, sub-boreal, and temperate forests. Accurate knowledge about forest understory reflectance is urgently needed in various forest reflectance modelling efforts. However, systematic collections of understory reflectance data covering different sites and ecosystems are almost missing. Measurement of understory reflectance is a real challenge because of an extremely high variability of irradiance at the forest floor, weak signal in some parts of the spectrum, spectral separability issues of over- and understory and its variable nature. Understory can consist of several sub-layers (regenerated tree, shrub, grasses or dwarf shrub, mosses, lichens, litter, bare soil), it has spatially-temporally variable species composition and ground coverage. Additional challenges are introduced by patchiness of ground vegetation, ground surface roughness, and understory-overstory relations. Due to this variability, remote sensing might be the only means to provide consistent data at spatially relevant scales. In this presentation, we report on retrieving seasonal courses of understory Normalized Difference Vegetation Index (NDVI) from multi-angular MODIS BRDF/Albedo data. We compared satellite-based seasonal courses of understory NDVI against an extended collection of different types of forest sites with available in-situ understory reflectance measurements. These sites are distributed along a wide latitudinal gradient on the Northern hemisphere: a sparse and dense black spruce forests in Alaska and Canada, a northern European boreal forest in Finland, hemiboreal needleleaf and deciduous stands in Estonia, a mixed temperate forest in Switzerland, a cool temperate deciduous broadleaf forest in Korea, and a semi-arid pine plantation in Israel. Our results indicated the retrieval method performs well particularly over open forests of different types. We also demonstrated

  8. Nitrogen dynamics in managed boreal forests: Recent advances and future research directions.

    Science.gov (United States)

    Sponseller, Ryan A; Gundale, Michael J; Futter, Martyn; Ring, Eva; Nordin, Annika; Näsholm, Torgny; Laudon, Hjalmar

    2016-02-01

    Nitrogen (N) availability plays multiple roles in the boreal landscape, as a limiting nutrient to forest growth, determinant of terrestrial biodiversity, and agent of eutrophication in aquatic ecosystems. We review existing research on forest N dynamics in northern landscapes and address the effects of management and environmental change on internal cycling and export. Current research foci include resolving the nutritional importance of different N forms to trees and establishing how tree-mycorrhizal relationships influence N limitation. In addition, understanding how forest responses to external N inputs are mediated by above- and belowground ecosystem compartments remains an important challenge. Finally, forestry generates a mosaic of successional patches in managed forest landscapes, with differing levels of N input, biological demand, and hydrological loss. The balance among these processes influences the temporal patterns of stream water chemistry and the long-term viability of forest growth. Ultimately, managing forests to keep pace with increasing demands for biomass production, while minimizing environmental degradation, will require multi-scale and interdisciplinary perspectives on landscape N dynamics. PMID:26744052

  9. Nitrogen and carbon reallocation in fungal mycelia during decomposition of boreal forest litter.

    Directory of Open Access Journals (Sweden)

    Johanna B Boberg

    Full Text Available Boreal forests are characterized by spatially heterogeneous soils with low N availability. The decomposition of coniferous litter in these systems is primarily performed by basidiomycete fungi, which often form large mycelia with a well-developed capacity to reallocate resources spatially- an advantageous trait in heterogeneous environments. In axenic microcosm systems we tested whether fungi increase their biomass production by reallocating N between Pinus sylvestris (Scots pine needles at different stages of decomposition. We estimated fungal biomass production by analysing the accumulation of the fungal cell wall compound chitin. Monospecific systems were compared with systems with interspecific interactions. We found that the fungi reallocated assimilated N and mycelial growth away from well-degraded litter towards fresh litter components. This redistribution was accompanied by reduced decomposition of older litter. Interconnection of substrates increased over-all fungal C use efficiency (i.e. the allocation of assimilated C to biomass rather than respiration, presumably by enabling fungal translocation of growth-limiting N to litter with higher C quality. Fungal connection between different substrates also restricted N-mineralization and production of dissolved organic N, suggesting that litter saprotrophs in boreal forest ecosystems primarily act to redistribute rather than release N. This spatial integration of different resource qualities was hindered by interspecific interactions, in which litters of contrasting quality were colonised by two different basidiomycete species. The experiments provide a detailed picture of how resource reallocation in two decomposer fungi leads to a more efficient utilisation of spatially separated resources under N-limitation. From an ecosystem point of view, such economic fungal behaviour could potentially contribute to organic matter accumulation in the litter layers of boreal forests.

  10. Charcoal reflectance reveals early holocene boreal deciduous forests burned at high intensities.

    Science.gov (United States)

    Hudspith, Victoria A; Belcher, Claire M; Kelly, Ryan; Hu, Feng Sheng

    2015-01-01

    Wildfire size, frequency, and severity are increasing in the Alaskan boreal forest in response to climate warming. One of the potential impacts of this changing fire regime is the alteration of successional trajectories, from black spruce to mixed stands dominated by aspen, a vegetation composition not experienced since the early Holocene. Such changes in vegetation composition may consequently alter the intensity of fires, influencing fire feedbacks to the ecosystem. Paleorecords document past wildfire-vegetation dynamics and as such, are imperative for our understanding of how these ecosystems will respond to future climate warming. For the first time, we have used reflectance measurements of macroscopic charcoal particles (>180μm) from an Alaskan lake-sediment record to estimate ancient charring temperatures (termed pyrolysis intensity). We demonstrate that pyrolysis intensity increased markedly from an interval of birch tundra 11 ky ago (mean 1.52%Ro; 485°C), to the expansion of trees on the landscape ~10.5 ky ago, remaining high to the present (mean 3.54%Ro; 640°C) irrespective of stand composition. Despite differing flammabilities and adaptations to fire, the highest pyrolysis intensities derive from two intervals with distinct vegetation compositions. 1) the expansion of mixed aspen and spruce woodland at 10 cal. kyr BP, and 2) the establishment of black spruce, and the modern boreal forest at 4 cal. kyr BP. Based on our analysis, we infer that predicted expansion of deciduous trees into the boreal forest in the future could lead to high intensity, but low severity fires, potentially moderating future climate-fire feedbacks. PMID:25853712

  11. Forest restoration, biodiversity and ecosystem functioning

    OpenAIRE

    Aerts Raf; Honnay Olivier

    2011-01-01

    Abstract Globally, forests cover nearly one third of the land area and they contain over 80% of terrestrial biodiversity. Both the extent and quality of forest habitat continue to decrease and the associated loss of biodiversity jeopardizes forest ecosystem functioning and the ability of forests to provide ecosystem services. In the light of the increasing population pressure, it is of major importance not only to conserve, but also to restore forest ecosystems. Ecological restoration has rec...

  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. A boreal invasion in response to climate change? Range shifts and community effects in the borderland between forest and tundra

    OpenAIRE

    Elmhagen, Bodil; Kindberg, Jonas; Hellström, Peter; Angerbjörn, Anders

    2015-01-01

    It has been hypothesized that climate warming will allow southern species to advance north and invade northern ecosystems. We review the changes in the Swedish mammal and bird community in boreal forest and alpine tundra since the nineteenth century, as well as suggested drivers of change. Observed changes include (1) range expansion and increased abundance in southern birds, ungulates, and carnivores; (2) range contraction and decline in northern birds and carnivores; and (3) abundance decli...

  14. 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.

  15. Simulating boreal forest carbon dynamics after stand-replacing fire disturbance: insights from a global process-based vegetation model

    Science.gov (United States)

    Yue, C.; Ciais, P.; Luyssaert, S.; Cadule, P.; Harden, J.; Randerson, J.; Bellassen, V.; Wang, T.; Piao, S.L.; Poulter, B.; Viovy, N.

    2013-01-01

    Stand-replacing fires are the dominant fire type in North American boreal forests. They leave a historical legacy of a mosaic landscape of different aged forest cohorts. This forest age dynamics must be included in vegetation models to accurately quantify the role of fire in the historical and current regional forest carbon balance. The present study adapted the global process-based vegetation model ORCHIDEE to simulate the CO2 emissions from boreal forest fire and the subsequent recovery after a stand-replacing fire; the model represents postfire new cohort establishment, forest stand structure and the self-thinning process. Simulation results are evaluated against observations of three clusters of postfire forest chronosequences in Canada and Alaska. The variables evaluated include: fire carbon emissions, CO2 fluxes (gross primary production, total ecosystem respiration and net ecosystem exchange), leaf area index, and biometric measurements (aboveground biomass carbon, forest floor carbon, woody debris carbon, stand individual density, stand basal area, and mean diameter at breast height). When forced by local climate and the atmospheric CO2 history at each chronosequence site, the model simulations generally match the observed CO2 fluxes and carbon stock data well, with model-measurement mean square root of deviation comparable with the measurement accuracy (for CO2 flux ~100 g C m−2 yr−1, for biomass carbon ~1000 g C m−2 and for soil carbon ~2000 g C m−2). We find that the current postfire forest carbon sink at the evaluation sites, as observed by chronosequence methods, is mainly due to a combination of historical CO2 increase and forest succession. Climate change and variability during this period offsets some of these expected carbon gains. The negative impacts of climate were a likely consequence of increasing water stress caused by significant temperature increases that were not matched by concurrent increases in precipitation. Our simulation

  16. Forest-climate feedbacks mediated through fire in the Eastern boreal forests of Canada

    Science.gov (United States)

    Bernier, P. Y.; Girardin, M. P.; Desjardins, R. L.; Gauthier, S.; Karimi-Zindashty, Y.; Worth, D.; Beaudoin, A.; Luo, Y.; Wang, S.

    2010-12-01

    Boreal forests are one of the largest biomes on earth, covering 27% of the world’s forests. In Canada, the dynamics of the boreal forests are largely dominated by large scale disturbances, with crown fires being the most geographically and temporally common. The probability of fire occurrence is strongly coupled to climate, making fire regimes quite variable across the country. Recent trends in fire regimes as well as predicted trends under climate scenarios also vary spatially. We present the results of two studies in which we have evaluated the climate - fire - forest feedbacks in parts of the boreal forest. Results show that feedbacks can be substantial and can alter the importance and even the direction of forest impacts on the climate system. The first feedback investigated was the link between fire-driven changes in forest cover properties and albedo in the boreal forests of Eastern Canada. Repeated disturbances in closed canopy forest dominated by black spruce (Picea mariana) on coarse soils sometimes push stands into an alternate stable open lichen woodland state. These lichen woodlands have a high albedo on account of the pale ground cover. Calculations show that the increase in albedo due to the opening of the canopy has a greater radiative forcing effect than that of the CO2 emitted to the atmosphere on account of the burning of the original forest. In these regions, climate-driven fire regimes thus generate a negative feedback to the climate system through their effects on forest cover properties. The second feedback investigated is linked to a recent decrease in fire frequency in Eastern Canada, and how this decrease might be affecting the growth-enhancing effect of a warmer climate because of its impact on the age-class distribution of the forest. The fire regime drives the age class distribution of forest landscapes. Since age class distribution drives landscape-level productivity, we have studied how this effect interacts with climate warming in

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

    Science.gov (United States)

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

    2012-11-01

    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 forest transition. Deer are more likely to browse saplings of temperate tree species, and European earthworms favour seedlings of boreal tree species more than temperate species, potentially hindering the ability of temperate tree species to expand northwards. We hypothesize that warming-induced changes in consumers will lead to novel plant communities by changing the filter on plant species success, and that above- and below-ground cascades of trophic interactions will allow boreal tree species to persist during early phases of warming, leading to an abrupt change at a later time. The synthesis of evidence suggests that consumers can modify the climate change-induced transition of ecosystems. PMID:23007083

  18. Impacts of a changing fire frequency on soil carbon stocks in interior Alaskan boreal forests

    Science.gov (United States)

    Hoy, E.; Kasischke, E. S.

    2011-12-01

    Vast reservoirs of carbon are present in the deep organic soils found in high northern latitude boreal forest ecosystems (> 200 Pg C in the ground layer alone), and these soils are susceptible to wildland fires, greatly impacting boreal forest carbon cycling. Recent climate change has resulted in a significant increase in average area burned across the North American boreal forest, which in turn has resulted in increasing fire frequency in many areas. In interior Alaska, black spruce (Picea mariana) forests represent 45% of the landscape, and are the prevailing forest type (66% of all forests); the deep organic soils in these black spruce forests represent the dominant terrestrial carbon reservoir in this region (1140.4 ± 117.3 Tg C). This research assesses the impacts of changes in fire frequency on carbon reservoirs present in surface organic soils in black spruce forests using a combination of geospatial and field data. The vulnerability of the landscape to more frequent reburning has been examined through analyses of landcover, topography and burned area data. Currently over 30% of the interior has burned since 1950, and 5% of the interior has burned 2 or more times in that period. In addition to the GIS analysis, field-based research has shown the impacts of fire frequency on the amount of residual soil organic matter remaining following fire. Using data collected from multiple black spruce stands located throughout the interior of Alaska we have seen differences between the amount of organic matter remaining following burning in mature and immature burned stands. It has been seen that while mature stands had deeper organic soils prior to burning, more frequent burning resulted in the loss of less organic material during burning and finally, less organic matter remained after the fire in immature burned stands (2.5 cm in immature burned stands compared with 10.1 cm in mature burned stands). Through this better understanding of frequent reburning within black

  19. Sorption of niobium on boreal forest soil

    International Nuclear Information System (INIS)

    The sorption of niobium (Nb) was investigated on humus and mineral soil samples taken from various depths of a four-metre deep forest soil pit on Olkiluoto Island, southwestern Finland. Mass distribution coefficients, Kd, were determined in batch sorption tests. The steady state of Nb sorption was observed in the mineral soil samples already after one week of equilibration, and sorption decreased with depth from a very high value of 185000 mL/g at 0.7 m to 54000 mL/g at 3.4 m. The reason behind this decrease is probably the tenfold reduction in the specific surface area of the soil at the same depth range. Distribution coefficients were clearly lower in the humus layer (1000 mL/g). The Kd values determined in pure water at a pH range of 4.7-6.5 were at a high level (above 55000 mL/g), but decreased dramatically above pH 6.5, corresponding to the change in the major Nb species from the neutral Nb(OH)5 to the low-sorbing anionic Nb(OH)6- and Nb(OH)72-. However, the Kd values in the model soil solution were in the slightly alkaline range an order of magnitude higher than in pure water, which is probably caused by the formation of calcium niobate surface precipitate or electrostatic interaction between surface-sorbed calcium and solute Nb. Among nine soil constituent minerals kaolinite performed best in retaining Nb in both pure water and model soil solution at pH 8, whereas potassium feldspar showed the poorest sorption. The Kd value for kaolinite was above 500000 mL/g in both solutions, while the respective potassium feldspar values were in the range of 120-220 mL/g.

  20. Sorption of niobium on boreal forest soil

    Energy Technology Data Exchange (ETDEWEB)

    Soederlund, Mervi; Hakanen, Martti; Lehto, Jukka [Helsinki Univ. (Finland). Lab. of Radiochemistry

    2015-07-01

    The sorption of niobium (Nb) was investigated on humus and mineral soil samples taken from various depths of a four-metre deep forest soil pit on Olkiluoto Island, southwestern Finland. Mass distribution coefficients, K{sub d}, were determined in batch sorption tests. The steady state of Nb sorption was observed in the mineral soil samples already after one week of equilibration, and sorption decreased with depth from a very high value of 185000 mL/g at 0.7 m to 54000 mL/g at 3.4 m. The reason behind this decrease is probably the tenfold reduction in the specific surface area of the soil at the same depth range. Distribution coefficients were clearly lower in the humus layer (1000 mL/g). The K{sub d} values determined in pure water at a pH range of 4.7-6.5 were at a high level (above 55000 mL/g), but decreased dramatically above pH 6.5, corresponding to the change in the major Nb species from the neutral Nb(OH){sub 5} to the low-sorbing anionic Nb(OH){sub 6}{sup -} and Nb(OH){sub 7}{sup 2-}. However, the K{sub d} values in the model soil solution were in the slightly alkaline range an order of magnitude higher than in pure water, which is probably caused by the formation of calcium niobate surface precipitate or electrostatic interaction between surface-sorbed calcium and solute Nb. Among nine soil constituent minerals kaolinite performed best in retaining Nb in both pure water and model soil solution at pH 8, whereas potassium feldspar showed the poorest sorption. The K{sub d} value for kaolinite was above 500000 mL/g in both solutions, while the respective potassium feldspar values were in the range of 120-220 mL/g.

  1. Countermeasure in forest ecosystems

    International Nuclear Information System (INIS)

    It is suggested that for economic reasons local governments in the areas of Sweden which are most contaminated from the Chernobyl major nuclear accident, as well as the forest companies, should have an interest in countermeasures for reducing the Cesium-137 acitivity concentrations in moose. This viewpoint is explained. Potassium fertilizing experiments were carried out on rocky ground with a shallow layer of soil or at a boggy area with peat soil. By fertilizing the heater, eaten by moose Cesium-137 activity could be reduced by 50%. The mean value was 11,000 Bq kg-1. The decrease occuring within 2-3 months also showed that there is an exchange of radiocesium in heather plants. There was found a large seasonal variation in the Cesium-137 activity concentration in roe-deer, so another countermeasure was to change the time of the hunting season from August to May where cesium activity in the meat was lowest. Deer were also given salt licks with Geisesalt (resulting in 50% reduction) and cesiumbinder in their fodder (as yet no reliable results) in furhter attempts to reduce cesium activity in their meat. Results are presented in the form of graphs. (AB)

  2. 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

  3. Altitudinal vs Latitudinal Climactic Drivers: A Comparison of a Relict Picea and Abies Forest in the Southern Appalachians versus the Hemi-Boreal Transition Zone off Southern Canada

    Science.gov (United States)

    Evans, A.; Lafon, C. W.

    2015-12-01

    Identification of biotic and abiotic determinants of tree species range limits is critical for understanding the effects of climate change on species distributions. Upward shifts of species distributions in montane areas have been widely reported but there have been few reports of latitudinal range retractions. Previous studies have indicated that southern latitudinal limits of a species range are dictated by biotic factors such as competition while others have suggested that abiotic factors, such as temperature, dictate these limits. We investigated the potential climatic gradients at the southern latitudinal limit of the Spruce (Picea) and Fir (Abies) species that dominate the Canadian boreal forest community as well as relict boreal forests containing similar species found in the high elevation areas of the Southern Appalachians. Existing research has suggested that relict ecosystems are more sensitive to climate change and can be indicative of future changes at latitudinal range limits. Expanding on this literature, we hypothesized that we would see similar gradients in climatic variables at the southern latitudinal limit of the Canadian boreal forest and those in the relict boreal forests southern Appalachians acting as controlling factors of these species distributions. We used forty years of climate data from weather stations along the southern edge of the boreal forest in the Canadian Shield provinces, species distribution data from the Canadian National Forest Inventory, (CNFI) geospatial data from the National Park Service (NPS), and historical weather data from the National Oceanic and Atmospheric Administration (NOAA) to perform our analysis. Our results indicate different climate variables act as controls of warm edge range limits of the Canadian boreal forest than those of the relict boreal forest of the southern Appalachians. However, we believe range retractions of the relict forest may be indicative of a more gradual response of similar species

  4. Habitat associations drive species vulnerability to climate change in boreal forests

    DEFF Research Database (Denmark)

    Mazziotta, Adriano; Triviño, Maria; Tikkanen, Olli Pekka;

    2016-01-01

    Species climate change vulnerability, their predisposition to be adversely affected, has been assessed for a limited portion of biodiversity. Our knowledge of climate change impacts is often based only on exposure, the magnitude of climatic variation in the area occupied by the species, even...... scenarios. However, climate change will potentially reduce habitat suitability for ~9–43 % of the threatened deadwood-associated species. This loss is likely caused by future increase in timber extraction and decomposition rates causing higher deadwood turnover, which have a strong negative effect on boreal...... forest biodiversity. Our results are species- and scenario-specific. Diversified forest management and restoration ensuring deadwood resources in the landscape would allow the persistence of species whose capacity of delivering important supporting ecosystem services can be undermined by climate change....

  5. 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

  6. 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.

  7. Management to conserve forest ecosystems

    Science.gov (United States)

    Robbins, C.S.

    1984-01-01

    Historically, management of forests for wildlife has emphasized creation of openings and provision for a maximum of edge habitats. Wildlife managers have believed, quite logically, that increased sunlight enhances productivity among plants and insects, resulting in greater use by game animals and other wildlife. Recent studies comparing breeding bird populations of extensive forests with those of isolated woodlots have shown that the smaller woodlots, especially those under 35 ha (about 85 acres), lack many species that are typical of the larger tracts. The missing species can be predicted, and basically are the neotropical migrants. These long-distance migrants share several characteristics that make them especially vulnerable to reproductive failure in situations where predation and cowbird parasitism are high: they are primarily single-brooded, open nesters that lay small clutches on or near the ground. Edge habitats and forest openings attract cowbirds and predators. The edge species of birds, which are mostly permanent residents or short-distance migrants, are well adapted to survive and reproduce in small isolated woodlands without the benefit of special habitat management. The obligate forest interior species, on the other hand, are decreasing in those parts of North America where extensive forests are being replaced by isolated woodlands. If we are to preserve ecosystems intact for the benefit of future generations, and maintain a viable gene pool for the scarcer species, we must think in terms of retaining large, unbroken tracts of forest and of limiting disturbance in the more remote portions of these tracts.

  8. 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

  9. Radionuclide transfer in forest ecosystems

    International Nuclear Information System (INIS)

    The behaviour of radionuclides in forest ecosystems differs substantially from the other ecosystems. The contamination of various forest products is commonly quantified using the Aggregated Transfer Factor (Tag in m2 kg-1) which integrates various environmental parameters including soil and plant type, root distribution as well as nature and vertical distribution of the deposits. This review aims at compiling the most relevant quantitative information on radionuclide transfers to forest biota including trees, understorey vegetation, mushrooms, berries and game animals. For both radiocaesium and radiostrontium in trees, the order of magnitude of mean Tag values is 10-3 m2.kg-1 (dry weight). The transfer of radionuclides to mushrooms and berries is high, in comparison with foodstuffs grown in agricultural systems. Concerning caesium uptake by mushrooms, the transfer is characterized by a very large variability of Tag, from 10-3 to 101 m2.kg-1 (dry weight). For berries, typical values are around 0.01 to 0.1 m2.kg-1 (dry weight). Transfer of radioactive caesium to game animals and reindeer and the rate of activity reduction, quantified as an ecological half-life, reflect the soil and pasture conditions at individual locations. Even if, the importance of radioactive contamination of forests as a significant source of the population exposure is recognized, most of the data refer to caesium and to a lesser extent, strontium. Data for other radionuclides are rather limited. (author)

  10. Priming effects in boreal black spruce forest soils: quantitative evaluation and sensitivity analysis.

    Directory of Open Access Journals (Sweden)

    Zhaosheng Fan

    Full Text Available Laboratory studies show that introduction of fresh and easily decomposable organic carbon (OC into soil-water systems can stimulate the decomposition of soil OC (SOC via priming effects in temperate forests, shrublands, grasslands, and agro-ecosystems. However, priming effects are still not well understood in the field setting for temperate ecosystems and virtually nothing is known about priming effects (e.g., existence, frequency, and magnitude in boreal ecosystems. In this study, a coupled dissolved OC (DOC transport and microbial biomass dynamics model was developed to simultaneously simulate co-occurring hydrological, physical, and biological processes and their interactions in soil pore-water systems. The developed model was then used to examine the importance of priming effects in two black spruce forest soils, with and without underlying permafrost. Our simulations showed that priming effects were strongly controlled by the frequency and intensity of DOC input, with greater priming effects associated with greater DOC inputs. Sensitivity analyses indicated that priming effects were most sensitive to variations in the quality of SOC, followed by variations in microbial biomass dynamics (i.e., microbial death and maintenance respiration, highlighting the urgent need to better discern these key parameters in future experiments and to consider these dynamics in existing ecosystem models. Water movement carries DOC to deep soil layers that have high SOC stocks in boreal soils. Thus, greater priming effects were predicted for the site with favorable water movement than for the site with limited water flow, suggesting that priming effects might be accelerated for sites where permafrost degradation leads to the formation of dry thermokarst.

  11. Ectomycorrhizal-dominated boreal and tropical forests have distinct fungal communities, but analogous spatial patterns across soil horizons.

    Directory of Open Access Journals (Sweden)

    Krista L McGuire

    Full Text Available Fungi regulate key nutrient cycling processes in many forest ecosystems, but their diversity and distribution within and across ecosystems are poorly understood. Here, we examine the spatial distribution of fungi across a boreal and tropical ecosystem, focusing on ectomycorrhizal fungi. We analyzed fungal community composition across litter (organic horizons and underlying soil horizons (0-20 cm using 454 pyrosequencing and clone library sequencing. In both forests, we found significant clustering of fungal communities by site and soil horizons with analogous patterns detected by both sequencing technologies. Free-living saprotrophic fungi dominated the recently-shed leaf litter and ectomycorrhizal fungi dominated the underlying soil horizons. This vertical pattern of fungal segregation has also been found in temperate and European boreal forests, suggesting that these results apply broadly to ectomycorrhizal-dominated systems, including tropical rain forests. Since ectomycorrhizal and free-living saprotrophic fungi have different influences on soil carbon and nitrogen dynamics, information on the spatial distribution of these functional groups will improve our understanding of forest nutrient cycling.

  12. 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.

  13. 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

  14. 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.

  15. Acid Precipitation and the Forest Ecosystem

    Science.gov (United States)

    Dochinger, Leon S.; Seliga, Thomas A.

    1975-01-01

    The First International Symposium on Acid Precipitation and the Forest Ecosystem dealt with the potential magnitude of the global effects of acid precipitation on aquatic ecosystems, forest soils, and forest vegetation. The problem is discussed in the light of atmospheric chemistry, transport, and precipitation. (Author/BT)

  16. 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...

  17. 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...

  18. Simulations of atmospheric OH, O3 and NO3 reactivities within and above the boreal forest

    DEFF Research Database (Denmark)

    Mogensen, D.; Gierens, R.; Crowley, J. N.;

    2015-01-01

    Using the 1-D 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 ...

  19. Comprehensive radiative forcing assesment highlights trade-offs in climate mitigation potential of managed boreal forests

    Science.gov (United States)

    Kalliokoski, Tuomo; Berninger, Frank; Bäck, Jaana; Boy, Michael; Kuusinen, Nea; Mäkelä, Annikki; Matthies, Brent; Minkkinen, Kari; Mogensen, Ditte; Peltoniemi, Mikko; Sievänen, Risto; Zhou, Luxi; Vanhatalo, Anni; Valsta, Lauri; Nikinmaa, Eero

    2016-04-01

    Boreal forests have an important role in the mitigation of climate change. In this study we evaluated four key climate impacts of forest management: (1) carbon sequestration (in forest ecosystems and wood products), (2) surface albedo of forest area, (3) forest originating Secondary Organic Aerosols (SOA) and (4) avoided CO2-emissions from wood energy and product substitution. We calculated their net effect at both a single stand and regional level using Finland as a case study. We made analyses both in current climate up to a year 2050 and in the projected climate of year 2050. At the stand level, the carbon sequestration effect and avoided CO2 emissions due to substituted materials dominated in net RF in current climate. The warming effect of surface albedo of forest cover was lower or of same magnitude than cooling effect of SOAs. Together, the rarely considered SOAs and product substitution corresponded over 70% of the total cooling effect of forest cover. The cooling effect of net radiative forcing increased along the increasing site fertility. Although the carbon stocks of broadleaved trees were smaller than that of conifers their total radiative cooling effect was larger due to the integrated albedo and aerosol effects. In the projected climate of 2050, the radiative cooling of aerosols approached the level of forest carbon fixation. These results emphasize the need for holistic evaluation of climate impacts over simple carbon sequestration analysis to understand the role of forest management in climate change mitigation. Landscape level analyses emphasized the broad range of options to reach the cooling effect. The lowest harvest regime, 50% of current annual increment (CAI), yielded the largest cooling effect. Yet, harvests up to CAI produced only slightly less cooling RF if avoided emissions were considered. This result was highly sensitive to used substitution factors. Our result highlights that the combination of intensive harvests and the use of wood

  20. Modeling the forest transition: forest scarcity and ecosystem service hypotheses.

    Science.gov (United States)

    Satake, Akiko; Rudel, Thomas K

    2007-10-01

    An historical generalization about forest cover change in which rapid deforestation gives way over time to forest restoration is called "the forest transition." Prior research on the forest transition leaves three important questions unanswered: (1) How does forest loss influence an individual landowner's incentives to reforest? (2) How does the forest recovery rate affect the likelihood of forest transition? (3) What happens after the forest transition occurs? The purpose of this paper is to develop a minimum model of the forest transition to answer these questions. We assume that deforestation caused by landowners' decisions and forest regeneration initiated by agricultural abandonment have aggregated effects that characterize entire landscapes. These effects include feedback mechanisms called the "forest scarcity" and "ecosystem service" hypotheses. In the forest scarcity hypothesis, forest losses make forest products scarcer, which increases the economic value of forests. In the ecosystem service hypothesis, the environmental degradation that accompanies the loss of forests causes the value of ecosystem services provided by forests to decline. We examined the impact of each mechanism on the likelihood of forest transition through an investigation of the equilibrium and stability of landscape dynamics. We found that the forest transition occurs only when landowners employ a low rate of future discounting. After the forest transition, regenerated forests are protected in a sustainable way if forests regenerate slowly. When forests regenerate rapidly, the forest scarcity hypothesis expects instability in which cycles of large-scale deforestation followed by forest regeneration repeatedly characterize the landscape. In contrast, the ecosystem service hypothesis predicts a catastrophic shift from a forested to an abandoned landscape when the amount of deforestation exceeds the critical level, which can lead to a resource degrading poverty trap. These findings imply

  1. The biogeochemistry of atmospherically derived Pb in the boreal forest of Sweden

    International Nuclear Information System (INIS)

    The use of stable Pb isotopes for tracing Pb contamination within the environment has strongly increased our understanding of the fate of airborne Pb contaminants within the boreal forest. This paper presents new stable Pb isotope (206Pb/207Pb ratio) measurements of solid soil samples, stream water (from a mire outlet and a stream draining a forest dominated catchment) and components of Picea abies (roots, needles and stemwood), and synthesizes some of the authors' recent findings regarding the biogeochemistry of Pb within the boreal forest. The data clearly indicate that the biogeochemical cycling of Pb in the present-day boreal forest ecosystem is dominated by pollution Pb from atmospheric deposition. The 206Pb/207Pb ratios of the mor layer (O-horizon), forest plants and stream water (mainly between 1.14 and 1.20) are similar to atmospheric Pb pollution (1.14-1.19), while the local geogenic Pb of the mineral soil (C-horizon) has high ratios (>1.30). Roots and basal stemwood of the analyzed forest trees have higher 206Pb/207Pb ratios (1.15-1.30) than needles and apical stemwood (1.14-1.18), which indicate that the latter components are more dominated by pollution derived Pb. The low 206Pb/207Pb ratios of the mor layer suggest that the upward transport of Pb as a result of plant uptake is small (-2 a-1) in comparison to atmospheric inputs (∼0.5 mg m-2 a-1) and annual losses with percolating soil-water (∼2 mg m-2 a-1); consequently, the Pb levels in the mor layer are now decreasing while the pool of Pb in the mineral soil is increasing. Streams draining mires appear more strongly affected by pollution Pb than streams from forested catchments, as indicated by Pb concentrations about three times higher and lower 206Pb/207Pb ratios (1.16 ± 0.01 in comparison to 1.18 ± 0.02). To what extent stream water Pb levels will respond to the build-up of Pb in deeper mineral soil layers remains uncertain

  2. Ecosystem Services and Forest Management in the Nordic Countries

    DEFF Research Database (Denmark)

    Filyushkina, Anna

    expert judgment method (the Delphi technique) was applied to preservation of biodiversity and habitat in the boreal zone. Results suggested that management intensity has a negative effect on the potential to preserve biodiversity and habitat. A wide range of estimates was provided by respondents for...... functional forms of relationships between preservation of biodiversity and forest characteristics, suggesting little agreement. The findings support the usefulness of the Delphi method as a complementary technique for in depth analysis of ecosystem services provision. A choice experiment approach was applied...

  3. A model inter-comparison study of forest growth on two coastal and boreal forest landscapes in Canada

    Science.gov (United States)

    Bernier, P. Y.; Wang, Z.; Grant, R. F.; Arain, A.; Chen, B.; Chen, J.; Coops, N.; Govind, A.; Guindon, L.; Hember, R.; Kurz, W. A.; Peng, C.; Price, D. T.; Stinson, G.; Sun, J.; Trofymow, J. A.

    2009-05-01

    Projection of carbon stocks in Canada is presently accomplished using CBM-CFS3, an inventory-based model. We have performed a comparison exercise among 6 process-based models of forest growth (Can-IBIS, INTEC, ECOSYS, 3PG, TRIPLEX, CN-CLASS) and CBM-CFS3 as part of an effort to better capture inter-annual climate variability in the carbon accounting of Canada's forests. Comparisons were made on multi-decadal simulations for a Pacific Coastal Douglas-fir forest (2500ha, Oyster River, British Columbia) and a Boreal Black Spruce forest (3825ha, Chibougamau, Quebec). Models were initiated using reconstructions of forest composition and biomass from 1920 (Oyster River, OR) and 1928 (Chibougamau, CH), followed by transition to current forest composition as derived from recent forest inventories (OR 1999, CH 1998). Forest management events and natural disturbances over the simulation period were provided as maps and disturbance impacts on a number of carbon pools were simulated using the same transfer coefficients parameters as CBM-CFS3. Simulations were conducted from 1920 to 2006 for OR, and from 1928 to 1998 for CH. For CH, final above-ground tree biomass in 1998 was also extracted from the independent forest inventory. The coastal OR area initially contained about four times more ecosystem C than the boreal CH area. CBM- CFS3 simulations suggest a decline in ecosystem carbon by about 200 Mg C ha-1, dominated by a loss of biomass and woody debris C, over the 86-year period in OR as the entire area transitioned from coastal old- growth to second growth conditions. In CH, a smaller proportion of the area was affected by management and the CBM-CFS3 estimated a small net increase in total ecosystem C of about 11 Mg C ha-1 over 70 years, almost all attributed to increased biomass. Changes in tree biomass at CH were 10% less than estimates derived by difference between successive inventories. The source of this small simulation bias is attributable to the underlying growth

  4. Boreal ditched forest and peatland are more vulnerable to forest fire than unditched areas

    Science.gov (United States)

    Köhler, Stephan J.; Granath, Gustav; Landahl, Anna; Fölster, Jens

    2016-04-01

    During summer of 2014 the largest wildfire in Swedish modern history occurred. The fire was ignited in a forest close to the Swedish town Sala and incinerated a total of 14 000 ha. The frequency of wildfires is expected to increase, due to effects of climate change such as increased temperature and decreased precipitation during the summer months. Wildfires can have a considerable impact on aquatic ecosystems and previous studies of wildfires have shown elevated concentrations of nutrients, cat- and anions. The area of the fire mainly consists of forestland, peatland and lakes and has been affected by acidification and intensive forestry. To assess the fire severity and the effects on the water chemistry, the fire severity were analyzed and classified using aerial phtographs and high resolution LIDAR data. The analysis indicated that increased fire intensity caused increased fire severity and that drained forested areas were more vulnerable to fire than undrained peatland. Measurements of water chemistry were conducted at nine streams and ten lakes inside the affected area. At two sites sensors for multiple parameters were deployed. During the initial three months of the post-fire period large peaks of ammonia-N and sulphate were observed in the streams and in a majority of the lakes while DOC was suppressed. In one stream Gärsjöbäcken the median concentrations of ammonia-N were 79 times higher after the fire. Due to nitrification the elevated concentrations of ammonia-N-nitrogen caused elevated concentrations of nitrate-nitrogen. The initial peak of sulphate caused a drop in ANC but after the peak had past ANC increased due to elevated concentrations of base cations. Correlation analysis of fire severity and water chemistry indicated that the maximum concentrations of ammonia-N increased with severely burned canopies in drained forested peatlands and in scorched open peatland. In a future climate with increased dry spells extensive ditching operations in

  5. 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.

  6. Simulating effects of fire disturbance and climate change on boreal forest productivity and evapotranspiration

    International Nuclear Information System (INIS)

    We used a terrestrial ecosystem process model, BIOME-BGC, to investigate historical climate change and fire disturbance effects on regional carbon and water budgets within a 357,500 km2 portion of the Canadian boreal forest. Historical patterns of increasing atmospheric CO2, climate change, and regional fire activity were used as model drivers to evaluate the relative effects of these impacts to spatial patterns and temporal trends in forest net primary production (NPP) and evapotranspiration (ET). Historical trends of increasing atmospheric CO2 resulted in overall 13% and 5% increases in annual NPP and ET from 1994 to 1996, respectively. NPP was found to be relatively sensitive to changes in air temperature (Ta), while ET was more sensitive to precipitation (P) change within the ranges of observed climate variability (e.g., +/-2 oC for Ta and +/-20% for P). In addition, the potential effect of climate change related warming on NPP is exacerbated or offset depending on whether these changes are accompanied by respective decreases or increases in precipitation. Historical fire activity generally resulted in reductions of both NPP and ET, which consumed an average of approximately 6% of annual NPP from 1959 to 1996. Areas currently occupied by dry conifer forests were found to be subject to more frequent fire activity, which consumed approximately 8% of annual NPP. The results of this study show that the North American boreal ecosystem is sensitive to historical patterns of increasing atmospheric CO2, climate change and regional fire activity. The relative impacts of these disturbances on NPP and ET interact in complex ways and are spatially variable depending on regional land cover and climate gradients. (author)

  7. Assessment of boreal forest historical C dynamics in the Yukon River Basin: relative roles of warming and fire regime change

    Science.gov (United States)

    Yuan, F.M.; Yi, S.H.; McGuire, A.D.; Johnson, K.D.; Liang, J.; Harden, J.W.; Kasischke, E.S.; Kurz, W.A.

    2012-01-01

    Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ∼0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink

  8. Assessment of boreal forest historical C dynamics in Yukon River Basin: relative roles of warming and fire regime change

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Fengming [ORNL; Yi, Shuhua [Cold and Arid Regions Environmental and Engineering Research Institute, CAS; McGuire, A. David [University of Alaska; Johnson, Kristopher D [University of Alaska, Fairbanks; Liang, Jingjing [University of Alaska, Fairbanks; Harden, Jennifer [USGS, Menlo Park, CA; Kasischke, Eric S. [University of Maryland, College Park; Kurz, Werner [Canadian Forest Service

    2012-01-01

    Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ;0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink

  9. Connecting forest ecosystem and microwave backscatter models

    Science.gov (United States)

    Kasischke, Eric S.; Christensen, Norman L., Jr.

    1990-01-01

    A procedure is outlined to connect data obtained from active microwave remote sensing systems with forest ecosystem models. The hierarchy of forest ecosystem models is discussed, and the levels at which microwave remote sensing data can be used as inputs are identified. In addition, techniques to utilize forest ecosystem models to assist in the validation of theoretical microwave backscatter models are identified. Several examples to illustrate these connecting processes are presented.

  10. 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

  11. Contribution of Soil CO2 Efflux to the Carbon Balance of Mature Deciduous and Coniferous Boreal Forests

    Science.gov (United States)

    Gaumont-Guay, D.; Black, A. T.; Barr, A.; McCaughey, H.; Kljun, N.; Morgenstern, K.; Nesic, Z.

    2004-05-01

    The Boreal Ecosystem Research and Monitoring Sites (BERMS) science team (now part of the Fluxnet Canada Research Network) is making long-term measurements of net CO2 ecosystem exchange (NEE) between the atmosphere and several Canadian boreal forests using the eddy covariance (EC) technique. In order to better understand and constrain the annual carbon budgets obtained with EC, automated soil CO2 efflux chamber systems were established in three of these stands. This study analyses continuous measurements of soil (Rs) and ecosystem (Re) respiration (i.e., soil CO2 efflux and nighttime NEE, respectively) made in 2003 in one deciduous (trembling aspen, SOA) and two coniferous (black spruce, SOBS and jack pine, SOJP) southern boreal forests. These forests are located 80 km apart in central Saskatchewan, Canada, and offer a unique opportunity to compare the response of different forest ecosystems to similar climate forcings. 2003 was characterized by an unprecented drought in western Canada, which significantly reduced the sink strength of these forests. The values of NEE in 2003 were -97, -62 and -29 g C m-2 y-1 (minus sign means uptake by ecosystem) for the respective sites. Overall, the measurements of Rs and Re using the two independent approaches agreed well. Re was largely dominated by Rs at all three sites, the latter accounting for more than 80% of total Re. Annual estimates of Rs were greater at SOA than at SOBS and SOJP, and likely reflect the higher productivity of the deciduous forest. The approximate values of Rs for the respective sites were 920, 600 and 540 g C m-2 y-1 in 2003. The spatial variability of Rs was greater at SOBS than at SOA and SOJP and was related to the heterogeneous nature of the moss-dominated forest-floor. The temporal variability of Rs at all sites was strongly controlled by soil temperature. The annual R10 and Q10 values computed from the relationships of Rs as a function of soil temperature at the 2-cm depth were 4.06, 2.43 and 1

  12. 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.

  13. Patterns of NPP, GPP, Respiration and NEP During Boreal Forest Succession

    Energy Technology Data Exchange (ETDEWEB)

    Goulden, Michael L.; McMillan, Andrew; Winston, Greg; Rocha, Adrian; Manies, Kristen; Harden, Jennifer W.; Bond-Lamberty, Benjamin

    2010-12-15

    We deployed a mesonet of year-round eddy covariance towers in boreal forest stands that last burned in ~1850, ~1930, 1964, 1981, 1989, 1998, and 2003 to understand how CO2 exchange changes during secondary succession.The strategy of using multiple methods, including biometry and micrometeorology, worked well. In particular, the three independent measures of NEP during succession gave similar results. A stratified and tiered approach to deploying eddy covariance systems that combines many lightweight and portable towers with a few permanent ones is likely to maximize the science return for a fixed investment. The existing conceptual models did a good job of capturing the dominant patterns of NPP, GPP, Respiration and NEP during succession. The initial loss of carbon following disturbance was neither as protracted nor large as predicted. This muted response reflects both the rapid regrowth of vegetation following fire and the prevalence of standing coarse woody debris following the fire, which is thought to decay slowly. In general, the patterns of forest recovery from disturbance should be expected to vary as a function of climate, ecosystem type and disturbance type. The NPP decline at the older stands appears related to increased Rauto rather than decreased GPP. The increase in Rauto in the older stands does not appear to be caused by accelerated maintenance respiration with increased biomass, and more likely involves increased allocation to fine root turnover, root metabolism, alternative forms of respiration, mycorrhizal relationships, or root exudates, possibly associated with progressive nutrient limitation. Several studies have now described a similar pattern of NEP following boreal fire, with 10-to-15 years of modest carbon loss followed by 50-to-100 years of modest carbon gain. This trend has been sufficiently replicated and evaluated using independent techniques that it can be used to quantify the likely effects of changes in boreal fire frequency and

  14. 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

  15. The impact of boreal deciduous and evergreen forests on atmospheric CO2 seasonality

    Science.gov (United States)

    Welp, L.; Graven, H. D.; Keeling, R. F.; Bi, J.

    2015-12-01

    The seasonal cycle of atmospheric CO2 is largely controlled by the terrestrial biosphere. It is well known that the seasonal amplitude of net ecosystem productivity (NEP) is the largest in the far north, where forest productivity is compressed into a short growing season. Since 1960, the seasonal amplitude of atmospheric CO2 north of 45N has increased by 35-55%. The increase in the seasonal amplitude is a difficult benchmark for coupled climate-carbon models to replicate. In fact, the models vary widely in their mean seasonal cycle representation. The boreal region has a strong influence on CO2 seasonality at Barrow. Deciduous and evergreen plant functional types (PFTs) have different patterns of NEP. We identified four pairs of nearby deciduous and evergreen forest PFTs with eddy covariance measurements. Evergreen forests show an early peak in NEP in May-June, while deciduous forests have a larger peak in NEP later in June-July. The influence of each PFT on the seasonal cycle at Barrow was computed from atmospheric transport results. We normalized the amplitude influence by the growing season NEP of the tower-based PFT flux and found that deciduous forests have 1.4 to 1.8 times more influence (per unit of growing season NEP) at Barrow than evergreen PFT. This diagnosis depends on the timing of the sharp seasonal draw-down at Barrow, which occurs too late to be explained by evergreen forests. The cycle at Barrow therefore appears to be strongly influenced by deciduous PFT, despite the dominance of evergreen PFTs in boreal forests. This paradoxical conclusion is also reached when examining the seasonality of land surface fluxes calculated using atmospheric inverse methods. We examine how these different PFTs, and possible trends in relative abundance, affect the seasonality of atmosphere CO2 using FluxNet data and atmospheric transport modelling. Our results highlight the importance of parameterizing multiple PFTs or individual species within grid cells in models in

  16. ASPECTS REGARDING LEGAL PROTECTION OF FOREST ECOSYSTEMS

    Directory of Open Access Journals (Sweden)

    Cristian Popescu

    2012-12-01

    Full Text Available The first legislative concerns for the protection and exploitation of forests are occurring since the eighteenth century. Forest of the country has always been a priority for environmental policy. The institutional framework for forestry organization in Romania is represented mainly by the Ministry of Environment and National Administration of Forests – Romsilva. First Romanian Forest Code was adopted on 19 June 1881. In present, the main law governing the forest is given by Law No. 46 of March 19, 2008 (Forest Code. Forests are resources of interest economic, social, recreational, ecological and biological. Biodiversity conservation of forest ecosystems involves the sustainable management by applying intensive treatments that promote natural regeneration of species of fundamental natural forest type and forest conservation and quasi virgin. The main way to conserve forest ecosystems is represented by the establishment of protected areas of national interest.

  17. Decadal and long-term boreal soil carbon and nitrogen sequestration rates across a variety of ecosystems

    Science.gov (United States)

    Manies, Kristen L.; Harden, Jennifer W.; Fuller, Christopher C.; Turetsky, Merritt R.

    2016-08-01

    Boreal soils play a critical role in the global carbon (C) cycle; therefore, it is important to understand the mechanisms that control soil C accumulation and loss for this region. Examining C & nitrogen (N) accumulation rates over decades to centuries may provide additional understanding of the dominant mechanisms for their storage, which can be masked by seasonal and interannual variability when investigated over the short term. We examined longer-term accumulation rates, using 210Pb and 14C to date soil layers, for a wide variety of boreal ecosystems: a black spruce forest, a shrub ecosystem, a tussock grass ecosystem, a sedge-dominated ecosystem, and a rich fen. All ecosystems had similar decadal C accumulation rates, averaging 84 ± 42 gC m-2 yr-1. Long-term (century) C accumulation rates were slower than decadal rates, averaging 14 ± 5 gC m-2 yr-1 for all ecosystems except the rich fen, for which the long-term C accumulation rates was more similar to decadal rates (44 ± 5 and 76 ± 9 gC m-2 yr-1, respectively). The rich fen also had the highest long-term N accumulation rates (2.7 gN m-2 yr-1). The lowest N accumulation rate, on both a decadal and long-term basis, was found in the black spruce forest (0.2 and 1.4 gN m-2 yr-1, respectively). Our results suggest that the controls on long-term C and N cycling at the rich fen is fundamentally different from the other ecosystems, likely due to differences in the predominant drivers of nutrient cycling (oxygen availability, for C) and reduced amounts of disturbance by fire (for C and N). This result implies that most shifts in ecosystem vegetation across the boreal region, driven by either climate or succession, will not significantly impact regional C or N dynamics over years to decades. However, ecosystem transitions to or from a rich fen will promote significant shifts in soil C and N storage.

  18. Organic matter biogeochemistry in the western boreal forest of Canada (Invited)

    Science.gov (United States)

    Norris, C. E.; Mercier Quideau, S.

    2013-12-01

    The western boreal forest of Canada is characterized by mixed and pure stands of aspen (Populus tremuloides Michx.), spruce (Picea glauca (Moench) Voss) and pine (Pinus banksiana Lamb.). This study presents results on the characterization and cycling of soil organic matter in these boreal ecosystems derived from examining both climatic and edaphic gradients. The extent of decomposition for pine forest floors was observed to decrease with increasing stand age and decreasing temperature along a latitudinal climatic transect as determined by solid state nuclear magnetic resonance. In a survey of mature aspen, spruce and pine sites, forest floors reflected the dominant vegetative inputs as demonstrated by long chain (≥ C21) n-alkane biomarkers. Utilizing a range of techniques, including compound-specific analysis of phospholipid fatty acids in a laboratory incubation, we determined that while soil microbial communities under aspen and spruce both readily consumed 13C-glucose, their structures remained unique. We also were interested in determining the response of aspen and spruce soil microbial communities to more complex vegetation inputs, and consequently generated double labelled (13C and 15N) aspen litter using multiple pulses of 13CO2(g) and K15NO3(l). Enriched aspen leaves were then applied in the field to the forest floors of aspen and spruce stands. Nitrogen cycling readily occurred on both sites as evidenced by 15N enrichment of above-ground vegetation. While the soil microbial community structures remained distinct between the two stand types across the field incubation, there was overlap in terms of the microorganisms involved in the decomposition of the applied organic matter.

  19. 3D simulation of boreal forests: structure and dynamics in complex terrain and in a changing climate

    Science.gov (United States)

    Brazhnik, Ksenia; Shugart, Herman H.

    2015-10-01

    To understand how the Siberian boreal forests may respond to near-future climate change, we employed a modeling approach and examined thresholds for significant and irreversible changes in forest structure and composition that are likely to be reached by mid-21st century. We applied the new spatially-explicit gap-dynamics model SIBBORK toward the understanding of how transition zones, namely treelines, which are notoriously undersampled and difficult to model, may change in the near future. We found that a 2 °C change in annual average air temperature significantly altered the structure, composition, and productivity of boreal forests stands both in the northern and the southern treeline ecotones. Treeline migration occurs at smaller temperature changes. Based on the current (1990-2014) observed warming trends, a 2 °C increase in annual average temperature compared to historical climate (1961-1990) is likely to be experienced at the northern treeline by 2040 and at the southern treeline by 2050. With regards to the forest biome, the most significant warming to date has been predicted and observed in Siberia. A 2 °C increase in annual average temperature compared to the second half of the 19th century is smaller than the predictions of even the most conservative RCP2.6 climate change scenario (IPCC 2013), and has previously been assumed to not likely result in dramatic changes to ecosystems or biome shifts. We show that at a +2 °C change, biome shifts from forest to steppe are likely to occur across a large area in southern Siberia. These changes in land cover will inevitably result in changes in the biodiversity, carbon storage, and the ecosystem services provided by the boreal forests of southern Siberia.

  20. 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

  1. Molecular and microscopic analysis of the gut contents of abundant rove beetle species (Coleoptera, Staphylinidae) in the boreal balsam fir forest of Quebec, Canada

    OpenAIRE

    Jan Klimaszewski; Marie-Josee Morency; Philippe Labrie; Armand Seguin; David Langor; Timothy Work; Caroline Bourdon; Evelyne Thiffault; David Pare; Alfred Newton; Margaret Thayer

    2013-01-01

    Experimental research on beetle responses to removal of logging residues following clearcut harvesting in the boreal balsam fir forest of Quebec revealed several abundant rove beetle (Staphylinidae) species potentially important for long-term monitoring. To understand the trophic affiliations of these species in forest ecosystems, it was necessary to analyze their gut contents. We used microscopic and molecular (DNA) methods to identify the gut contents of the following rove beetles: Atheta c...

  2. 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

  3. Coupling of soil prokaryotic diversity and plant diversity across latitudinal forest ecosystems

    OpenAIRE

    Jun-Tao Wang; Yuan-Ming Zheng; Hang-Wei Hu; Jing Li; Li-Mei Zhang; Bao-Dong Chen; Wei-Ping Chen; Ji-Zheng He

    2016-01-01

    The belowground soil prokaryotic community plays a cardinal role in sustaining the stability and functions of forest ecosystems. Yet, the nature of how soil prokaryotic diversity co-varies with aboveground plant diversity along a latitudinal gradient remains elusive. By establishing three hundred 400-m2 quadrats from tropical rainforest to boreal forest in a large-scale parallel study on both belowground soil prokaryote and aboveground tree and herb communities, we found that soil prokaryotic...

  4. Multielement composition of the aerosols of the forest fires of boreal forests upon burning of forest combustibles

    International Nuclear Information System (INIS)

    The results of the SRXFA determination of the multielement composition of aerosols forming on fires in the boreal forests of Siberia are given. A comparison of the multielement composition of aerosols in the convective column of large forest fires and smoke plumes of surface fires with that of atmospheric aerosols of the Siberian region shows that the mass concentration of all analyzed elements exceeds the background values upon fires. A substantial change is observed in the quantitative composition of the aerosols

  5. 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.

  6. 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

    G P, Alix C, Barber V A, Winslow S E, Sousa E E, Heiser P, Herriges J D and Goetz S J 2011 Changes in forest productivity across Alaska consistent with biome shift Ecol. Lett. 14 373-9 Berner L T, Beck P S A, Bunn A G, Lloyd A H and Goetz S J 2011 High-latitude tree growth and satellite vegetation indices: correlations and trends in Russia and Canada (1982-2008) J. Geophys. Res. 116 G01015 Bunn A G and Goetz S J 2006 Trends in satellite-observed circumpolar photosynthetic activity from 1982 to 2003: the influence of seasonality, cover type, and vegetation density Earth Interact. 10 1-19 D'Arrigo R, Jacoby G, Buckley B, Sakulich J, Frank D, Wilson R, Curtis A and Anchukaitis K 2009 Tree growth and inferred temperature variability at the North American Arctic treeline Glob. Planet. Change 65 71-82 D'Arrigo R, Wilson R, Liepert B, Cherubini P 2008 On the 'divergence problem' in northern forests: a review of the tree-ring evidence and possible causes Glob. Planet. Change 60 289-305 Davi N K, Jacoby G C and Wiles G C 2003 Boreal temperature variability inferred from maximum latewood density and tree-ring width data, Wrangell Mountain region, Alaska Quatern. Res. 60 252-62 Flexas J, Bota J, Loreto F, Cornic G and Sharkey T 2004 Diffusive and metabolic limitations to photosynthesis under drought and salinity in C3 plants Plant Biol. 6 269-79 Goetz S J, Bunn A G, Fiske G J and Houghton R 2005 Satellite-observed photosynthetic trends across boreal North America associated with climate and fire disturbance Proc. Natl Acad. Sci. USA 102 13521-5 Goetz S J, Kimball J S, Mack M C and Kasischke E S 2011 Scoping completed for an experiment to assess vulnerability of Arctic and boreal ecosystems EOS Trans. Am. Geophys. Union 92 150-1 McDowell N G 2011 Mechanisms linking drought, hydraulics, carbon metabolism, and vegetation mortality Plant Physiol. 155 1051-9 McGuire A D, Ruess R W, Lloyd A, Yarie J, Clein J S and Juday G P 2010 Vulnerability of white spruce tree growth in interior

  7. 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.

  8. Estimating aboveground biomass in the boreal forests of the Yukon River Basin, Alaska

    Science.gov (United States)

    Ji, L.; Wylie, B. K.; Nossov, D.; Peterson, B.; Waldrop, M. P.; McFarland, J.; Alexander, H. D.; Mack, M. C.; Rover, J. A.; Chen, X.

    2011-12-01

    Quantification of aboveground biomass (AGB) in Alaska's boreal forests is essential to accurately evaluate terrestrial carbon stocks and dynamics in northern high-latitude ecosystems. However, regional AGB datasets with spatially detailed information (DBH) or basal diameter (BD) for live and dead trees and shrubs (>1 m tall), which were converted to plot-level AGB using allometric equations. We acquired Landsat Enhanced Thematic Mapper Plus (ETM+) images from the Web Enabled Landsat Data (WELD) that provides multi-date composites of top-of-atmosphere reflectance and brightness temperature for Alaska. From the WELD images, we generated a three-year (2008 - 2010) image composite for the Yukon River Basin using a series of compositing criteria including non-saturation, non-cloudiness, maximal normalize difference vegetation index (NDVI), and maximal brightness temperature. Airborne lidar datasets were acquired for two sub-regions in the central basin in 2009, which were converted to vegetation height datasets using the bare-earth digital surface model (DSM) and the first-return DSM. We created a multiple regression model in which the response variable was the field-observed AGB and the predictor variables were Landsat-derived reflectance, brightness temperature, and spectral vegetation indices including NDVI, soil adjusted vegetation index (SAVI), enhanced vegetation index (EVI), normalized difference infrared index (NDII), and normalized difference water index (NDWI). Principal component analysis was incorporated in the regression model to remedy the multicollinearity problems caused by high correlations between predictor variables. The model fitted the observed data well with an R-square of 0.62, mean absolute error of 29.1 Mg/ha, and mean bias error of 3.9 Mg/ha. By applying this model to the Landsat mosaic, we generated a 30-m AGB map for the boreal forests in the Yukon River Basin. Validation of the Landsat-derived AGB using the lidar dataset indicated a

  9. Seasonality and nitrogen supply modify carbon partitioning in understory vegetation of a boreal coniferous forest.

    Science.gov (United States)

    Hasselquist, N J; Metcalfe, D B; Marshall, J D; Lucas, R W; Högberg, P

    2016-03-01

    Given the strong coupling between the carbon (C) and nitrogen (N) cycles, there is substantial interest in understanding how N availability affects C cycling in terrestrial ecosystems, especially in ecosystems limited by N. However, most studies in temperate and boreal forests have focused on the effects of N addition on tree growth. By comparison, less is known about the effects of N availability on the cycling of C in understory vegetation despite some evidence that dwarf shrubs, mosses, and lichens play an important role in the forest C balance. In this study, we used an in situ 13CO2 pulse-labeling technique to examine the short-term dynamics of C partitioning in understory vegetation in three boreal Pinus sylvestris forest stands exposed to different rates of N addition: a low and high N addition that receive annual additions of NH4NO3 of 20 and 100 kg N/ha, respectively, and this is a typo. It should be an unfertilized control. Labeling was conducted at two distinct periods (early vs. late growing season), which provided a seasonal picture of how N addition affects C dynamics in understory vegetation. In contrast to what has been found in trees, there was no obvious trend in belowground C partitioning in ericaceous plants in response to N additions or seasonality. Increasing N addition led to a greater percentage of 13C being incorporated into ericaceous leaves with a high turnover, whereas high rates of N addition strongly reduced the incorporation of 13C into less degradable moss tissues. Addition of N also resulted in a greater percentage of the 13C label being respired back to the atmosphere and an overall reduction in total understory carbon use efficiency. Taken together, our results suggest a faster cycling of C in understory vegetation with increasing N additions; yet the magnitude of this general response was strongly dependent on the amount of N added and varied seasonally. These results provide some of the first in situ C and N partitioning

  10. Patterns of NPP, GPP, respiration, and NEP during boreal forest succession

    Science.gov (United States)

    Goulden, M.L.; Mcmillan, A.M.S.; Winston, G.C.; Rocha, A.V.; Manies, K.L.; Harden, J.W.; Bond-Lamberty, B. P.

    2011-01-01

    We combined year-round eddy covariance with biometry and biomass harvests along a chronosequence of boreal forest stands that were 1, 6, 15, 23, 40, 74, and 154 years old to understand how ecosystem production and carbon stocks change during recovery from stand-replacing crown fire. Live biomass (Clive) was low in the 1 and 6 year old stands, and increased following a logistic pattern to high levels in the 74 and 154year old stands. Carbon stocks in the forest floor (Cforest floor) and coarse woody debris (CCWD) were comparatively high in the 1year old stand, reduced in the 6 through 40year old stands, and highest in the 74 and 154year old stands. Total net primary production (TNPP) was reduced in the 1 and 6year old stands, highest in the 23 through 74year old stands and somewhat reduced in the 154year old stand. The NPP decline at the 154year old stand was related to increased autotrophic respiration rather than decreased gross primary production (GPP). Net ecosystem production (NEP), calculated by integrated eddy covariance, indicated the 1 and 6 year old stands were losing carbon, the 15year old stand was gaining a small amount of carbon, the 23 and 74year old stands were gaining considerable carbon, and the 40 and 154year old stands were gaining modest amounts of carbon. The recovery from fire was rapid; a linear fit through the NEP observations at the 6 and 15year old stands indicated the transition from carbon source to sink occurred within 11-12 years. The NEP decline at the 154year old stand appears related to increased losses from Clive by tree mortality and possibly from Cforest floor by decomposition. Our findings support the idea that NPP, carbon production efficiency (NPP/GPP), NEP, and carbon storage efficiency (NEP/TNPP) all decrease in old boreal stands. ?? 2010 Blackwell Publishing Ltd.

  11. 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...

  12. 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.

  13. 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.

  14. Understanding the Effect of Land Cover Classification on Model Estimates of Regional Carbon Cycling in the Boreal Forest Biome

    Science.gov (United States)

    Kimball, John; Kang, Sinkyu

    2003-01-01

    The original objectives of this proposed 3-year project were to: 1) quantify the respective contributions of land cover and disturbance (i.e., wild fire) to uncertainty associated with regional carbon source/sink estimates produced by a variety of boreal ecosystem models; 2) identify the model processes responsible for differences in simulated carbon source/sink patterns for the boreal forest; 3) validate model outputs using tower and field- based estimates of NEP and NPP; and 4) recommend/prioritize improvements to boreal ecosystem carbon models, which will better constrain regional source/sink estimates for atmospheric C02. These original objectives were subsequently distilled to fit within the constraints of a 1 -year study. This revised study involved a regional model intercomparison over the BOREAS study region involving Biome-BGC, and TEM (A.D. McGuire, UAF) ecosystem models. The major focus of these revised activities involved quantifying the sensitivity of regional model predictions associated with land cover classification uncertainties. We also evaluated the individual and combined effects of historical fire activity, historical atmospheric CO2 concentrations, and climate change on carbon and water flux simulations within the BOREAS study region.

  15. 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.

  16. 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

  17. Carbon balance of an old hemi-boreal pine forest in Southern Estonia determined by different methods

    Science.gov (United States)

    Soosaar, Kaido; Repp, Kalev; Lõhmus, Krista; Uri, Veiko; Rannik, Kaire; Krasnova, Alisa; Ostonen, Ivika; Kukumägi, Mai; Maddison, Martin; Mander, Ülo

    2016-04-01

    The Soontaga Forest Station is located in hemi-boreal 200-years old pine forest (South Estonia; 58o01'N 26o04'E) with a second layer of spruce. The station has the instrumentation to assess the exchange of carbon dioxide (net ecosystem exchange, NEE), soil respiration, tree biomass (above and below ground biomass) and different environmental and meteorological parameters. In this study we quantified carbon balance by analyzing eddy-covariance CO2 flux data (carbon exchange) vs chamber-based measurements (ecosystem respiration) and CO2assimilation (soil and biomass). The annual NEE in this mature coniferous forest was -2.3 t C ha yr‑1, showing a clear diurnal and seasonal trend. During the daytime in summer the forest sequestered CO2, while during the night and late night CO2 emitted from the ecosystem to the atmosphere. Within the growing period, the sequestration of CO2 by plants was greater than soil respiration. Thus, the ecosystem sequestered carbon. Most of the carbon is bound in tree biomass (above and below ground biomass) but as well into soil, while the sequestration in soil increases with stand age. In addition, the biomass of understory, especially belowground litter, is playing essential part in carbon input. A modelling approach of long-term C budget in the Soontaga pine forest is presented.

  18. Form, quantity, and fate of nitrogen inputs along a boreal forest climate transect

    Science.gov (United States)

    VandenBoer, T. C.; Edwards, K.; Ziegler, S. E.

    2013-12-01

    The cycling and fate of soil organic matter, a globally significant carbon (C) reservoir, is intimately linked to the availability and form of nitrogen (N). Nitrogen inputs to remote ecosystems from the atmosphere have been accelerated by increases in agricultural fertilizer use, and fossil fuel use. Such inputs may influence the biogeochemistry of high latitude ecosystems where soil organic matter reservoirs are particularly vulnerable to climate change. The Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect (NL-BELT) network has been actively monitoring C and N pools across three watershed regions spanning 47° to 53° N to understand boreal forest ecosystem responses to a warming climate. Litterfall inputs exhibited decreasing stable nitrogen isotope (d15N) values from south to north along the transect (-2, -3, and -6 ‰) and also among litter sources (deciduous > green needles > brown needles). These regional trends in d15N persist in the bryophytic biomass and throughout the soil organic horizons. Litterfall C:N increased from approximately 55 in the south to 75 in the north. In each region, C:N also exhibited consistent patterns between litterfall input types, with C:N of brown needles > deciduous > green needles. Differences between green and brown needle litterfall C:N increased along this climate gradient indicating that trees increased their N-resorption from south to north, perhaps due to increased N-limitation. Two possible phenomena could explain the trends observed: i) atmospheric N-inputs vary in quantity and composition with latitude along the transect; and/or ii) more rapid recycling of N at the most southern site reduces N-limitation relative to cooler regions. Fractionation during long-range transport of atmospheric reactive-N leads to depletion of 15N and subsequent deposition to the NL-BELT regions could explain these observations. The forms and quantities of atmospheric N-inputs are not constrained for the NL-BELT forests and

  19. Annual Dynamics of Green House Gases in a Swedish Boreal Forested Catchment

    Science.gov (United States)

    Oquist, M. G.; Klemedtsson, L.; Bishop, K.; Grip, H.; Laudon, H.; Nilsson, M.

    2003-04-01

    We investigated the spatial and temporal variation of CO_2, CH_4 and N_2O in a boreal forested catchment with respect to their atmospheric exchange and their below-ground concentration dynamics. The measurements were carried out at three sites distributed along a gently sloping 22 m transect draining into a small creek. Vegetation was dominated by a 95 year old Norway spruce stand and soil types ranged from organic (a riparian zone histosol) to mineral (podzol on sandy till). Soil gas concentrations (at 5, 10, 20, 40 and 60 cm depth) were measured weekly for 18 months, while gas fluxes were measured weekly during the snow-free season and at 4 campaigns during the winter season. During the growing season average CO_2 efflux from the three sites ranged from 0.7--1.8 g m-2 d-1, while CH_4 displayed a net uptake rate of 0.1--0.3 mg m-2 d-1. Detectable amounts of N_2O emissions appeared sporadically, but never exceeded 0.04 mg m-2 d-1. The variation in CO_2 flux had the same temporal pattern as the variation in soil temperature (5--25 cm depth; r^2 = 0.6--0.85), while ca 40% of the differences in CH_4 consumption could be accounted for by the variations in soil moisture in the top 20 cm. During winter, fluxes of CO_2 and CH_4 were of the same order of magnitude as during summer, but the N_2O emissions were considerably higher, averaging around 0.4 mg m-2 d-1. Furthermore, soil gas concentrations of N_2O during winter showed a strong positive temperature correlation with a ca10-fold increase in concentration per ^oC (r^2 = 0.93). Our results stress the importance of the winter season for the greenhouse gas dynamics of the boreal landscape, and also that both N_2O and CH_4 exchange have the potential to influence how these ecosystems interact with the Earth's radiative balance. Moreover, the strength of atmospheric CH_4 consumption rates in these systems appears to be indifferent to season, which has implications for regional estimates of CH_4 budgets. The temperature

  20. Impacts of Climate Change on Forest Ecosystems in Northeast China

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Ying; ZHAO Chun-Yu; JIA Qing-Yu

    2013-01-01

    This paper reviews the studies and research on climate change impacts on the forest ecosystems in Northeast China. The results show that in the context of global and regional warming, the growing season of coniferous forests has been increasing at an average rate of 3.9 d per decade. Regional warming favors the growth of temperate broad-leaved forests and has a detrimental effect on the growth of boreal coniferous forests. Over the past hundred years, the forest edge of the cool temperate zone in the southern Daxing’anling region has retreated 140 km northward. From 1896 to 1986, the northern boundary of broad-leaved forests in Heilongjiang province has extended northwestward about 290 km. Future climatic changes (until 2060) may lead to the northern deciduous needle forests moving out of China’s territory altogether. The occurrence cycles of pests and diseases have shortened; their distribution ranges have expanded. The life cycle of tent caterpillars (Malacosoma neustria testacea Motschulsky) has shortened from 14-15 years in the past to 8-10 years now. The pine caterpillar (Dendrolimus tabulaeformis Tsai et Liu), which has spread within western Liaoning province and the nearby areas, can now be found in the north and west. Lightning fires in the Daxing’anling region have significantly increased since 1987, and August has become the month when lightning fires occur most frequently. Overall, the net primary productivity (NPP) of forest in Northeast China has increased. The NPP in 1981 was around 0.27 Pg C, and increased to approximately 0.40 Pg C in 2002. With the current climate, the broad-leaved Korean pine forest ecosystem acts as a carbon sink, with a carbon sink capacity of 2.7 Mg C hm-2. Although the carbon sink capacity of the forest ecosystems in Northeast China has been weakened since 2003, the total carbon absorption will still increase. The forest ecosystems in Northeast China are likely to remain a significant carbon sink, and will play a

  1. 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

  2. Climatic factors and reindeer grazing -- the effects on soil carbon dynamics in subarctic boreal pine forest.

    Science.gov (United States)

    Köster, Kajar; Köster, Egle; Berninger, Frank; Pumpanen, Jukka

    2016-04-01

    Reindeer (Rangifer tarandus L.) are the most important large mammalian herbivores in the northern ecosystems, affecting plant diversity, soil nutrient cycling and soil organic matter decomposition. Changes caused by reindeer in vegetation have indirect effects on physical features of the soil e.g. soil microclimate, root biomass and also on soil carbon dynamics. In a field experiment in Finnish Lapland, Värriö Strict Nature Reserve (67° 46' N, 29° 35' E) we investigated how the reindeer grazing in subarctic boreal forest combined with climate (air temperature and precipitation) affects soil temperature, soil water content, and ultimately the CO2 efflux from forest soils. The study was carried out in the growing seasons of the years 2013 and 2014, where 2013 was an extremely dry year (specially the summer), and the year 2014 was a "normal" year in means of precipitations. Our study areas are located in the northern boreal subarctic coniferous forest at the zone of the last intact forest landscapes in Fennoscandia, where large areas of relatively undisturbed subarctic Scots pine (Pinus sylvestris L.) forests can still be found. We established the experiment as a split plot experiment with 2 blocks and 5 sub-plots per treatment that were divided into grazed and non-grazed parts, separated with a fence. The sample plots are located along the borderline between Finland and Russia, where the ungrazed area was excluded from reindeer already in 1918, to prevent the Finnish reindeer from going to the Russian side and there are not many reindeer on Russian side of the area. Our study showed that in subarctic mature pine forests, soil temperatures were higher, and soil water content was fluctuating more on grazed areas compared to non-grazed areas in both years. In both years, the soil water content on the grazed area was highest in June. The situation changed somewhere in the second half of July when the moisture content in the non-grazed area was higher. We found

  3. Remote Sensing of Boreal Forest Biophysical and Inventory Parameters: A Review

    Science.gov (United States)

    Lutz, D. A.; Washington-Allen, R. A.

    2007-12-01

    Vegetation makes up nearly 70 % of the Earth's terrestrial surface and products from vegetated systems are vitally important for human populations. The growing need to manage vegetation resources at regional and global spatial scales has led to the increased use of remote sensing technologies among forestry scientists and managers for use in their investigation and supervision of forested landscapes. With a panoply of extant and developing airborne and satellite sensors, as well as multiple analysis techniques, there is a need to discern the most acceptable methods in which to examine remotely sensed imagery for forest ecosystem parameters. This includes both biophysical and inventory indicators. This study investigates the methods used to examine plant parameters in the boreal forest, and attempts to derive the most appropriate methods for extracting information regarding plant structure and stand information. A suggested methodology is constructed for use by remote sensors and forest managers. Specifically, we reviewed the literature on the remote sensing of boreal forests that featured airborne and satellite optical, passive and active radar, and lidar systems in order to determine if common frameworks for monitoring and assessing change in forest biophysical and inventory parameters could be developed. Other important remote sensing techniques such as change detection and land cover identification were also examined. Our review considered the purpose of each study, the type of sensor(s) used [e.g., Landsat or Lidar], where the study occurred, the methods used, including what vegetation and soil parameters or processes were considered, and the remote sensing indicator developed to measure this parameter [e.g., the normalized difference vegetation index (NDVI) is a surrogate for phytomass, LAI, land cover type, and other plant parameters]. We also investigated how the measured indicators were calibrated and validated as well as the limitations of the sensors that

  4. 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...

  5. 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.

  6. 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.

  7. 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 ...

  8. 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

  9. 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.

  10. 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.

  11. 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...

  12. 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...

  13. 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.

  14. Carbon-nitrogen interactions in forest ecosystems

    DEFF Research Database (Denmark)

    Gundersen, Per; Berg, Bjørn; Currie, W.S.;

    This report is a summary of the main results from the EU project “Carbon – Nitrogen Interactions in Forest Ecosystems” (CNTER). Since carbon (C) and nitrogen (N) are bound together in organic matter we studied both the effect of N deposition on C cycling in forest ecosystems, and the effect of C...... accumulation on N storage and release. Based on compiled databases on element pools and fluxes from several hundred forest sites, process studies in long-term nitrogen manipulation experiments and modelling efforts we estimated C sequestration and N retention in European forest soils. Further, we studied the...... impact of forest management on C sequestration, N retention and N leaching....

  15. Coupling of soil prokaryotic diversity and plant diversity across latitudinal forest ecosystems

    Science.gov (United States)

    Wang, Jun-Tao; Zheng, Yuan-Ming; Hu, Hang-Wei; Li, Jing; Zhang, Li-Mei; Chen, Bao-Dong; Chen, Wei-Ping; He, Ji-Zheng

    2016-01-01

    The belowground soil prokaryotic community plays a cardinal role in sustaining the stability and functions of forest ecosystems. Yet, the nature of how soil prokaryotic diversity co-varies with aboveground plant diversity along a latitudinal gradient remains elusive. By establishing three hundred 400-m2 quadrats from tropical rainforest to boreal forest in a large-scale parallel study on both belowground soil prokaryote and aboveground tree and herb communities, we found that soil prokaryotic diversity couples with the diversity of herbs rather than trees. The diversity of prokaryotes and herbs responds similarly to environmental factors along the latitudinal gradient. These findings revealed that herbs provide a good predictor of belowground biodiversity in forest ecosystems, and provide new perspective on the aboveground and belowground interactions in forest ecosystems.

  16. 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

  17. 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

  18. The impact of climate change on forest fire danger rating in China's boreal forest

    Institute of Scientific and Technical Information of China (English)

    YANG Guang; DI Xue-ying; GUO Qing-xi; SHU Zhan; ZENG Tao; YU Hong-zhou; WANG Chao

    2011-01-01

    The Great Xing'an Mountains boreal forests were focused on in the northeastern China.The simulated future climate scenarios of IPCC SRES A2a and B2a for both the baseline period of 1961-1990 and the future scenario periods were downscaled by the Delta Method and the Weather Generator to produce daily weather data.After the verification with local weather and fire data, the Canadian Forest Fire Weather Index System was used to assess the forest fire weather situation under climate change in the study region.An increasing trend of fire weather severity was found over the 21st century in the study region under the both future climate change scenarios, compared to the 1961-1990 baseline period.The annual mean/maximum fire weather index was predicted to rise continuously during 2010-2099, and by the end of the 21st century it is predicted to rise by 22%-52% across much of China's boreal forest.The significant increases were predicted in the spring from of April to June and in the summer from July to August.In the summer, the fire weather index was predicted to be higher than the current index by as much as 148% by the end of the 21st century.Under the scenarios of SRES A2a and B2a, both the chance of extremely high fire danger occurrence and the number of days of extremely high fire danger occurrence was predieted to increase in the study region.It is anticipated that the number of extremely high fire danger days would increase from 44 days in 1980s to 53-75 days by the end of the 21st century.

  19. Regional Instability in the Abundance of Open Stands in the Boreal Forest of Eastern Canada

    Directory of Open Access Journals (Sweden)

    Rija Rapanoela

    2016-05-01

    Full Text Available 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-moss stands tend, however, to diminish in favour of more open stands similar to spruce-lichen stands when subjected to more frequent and recurring disturbances. This study therefore focused on the effects of spatial and temporal variations in burn rates on the proportion of open stands over a large geographic area (175,000 km2 covered by black spruce (Picea mariana (Mill. Britton, Sterns, Poggenb.. The study area was divided into 10 different zones according to burn rates, as measured using fire-related data collected between 1940 and 2006. To test if the abundance of open stands was unstable over time and not in equilibrium with the current fire regime, forest succession was simulated using a landscape dynamics model that showed that the abundance of open stands should increase progressively over time in zones where the average burn rate is high. The proportion of open stands generated during a specific historical period is correlated with the burn rate observed during the same period. Rising annual burn rates over the past two decades have thereby resulted in an immediate increase in the proportion of open stands. There is therefore a difference between the current proportion of open stands and the one expected if vegetation was in equilibrium with the disturbance regime, reflecting an instability that may significantly impact the way forest resources are managed. It is apparent from this study that forestry planning should consider the risks associated

  20. 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...

  1. Forest restoration, biodiversity and ecosystem functioning

    Directory of Open Access Journals (Sweden)

    Aerts Raf

    2011-11-01

    Full Text Available Abstract Globally, forests cover nearly one third of the land area and they contain over 80% of terrestrial biodiversity. Both the extent and quality of forest habitat continue to decrease and the associated loss of biodiversity jeopardizes forest ecosystem functioning and the ability of forests to provide ecosystem services. In the light of the increasing population pressure, it is of major importance not only to conserve, but also to restore forest ecosystems. Ecological restoration has recently started to adopt insights from the biodiversity-ecosystem functioning (BEF perspective. Central is the focus on restoring the relation between biodiversity and ecosystem functioning. Here we provide an overview of important considerations related to forest restoration that can be inferred from this BEF-perspective. Restoring multiple forest functions requires multiple species. It is highly unlikely that species-poor plantations, which may be optimal for above-ground biomass production, will outperform species diverse assemblages for a combination of functions, including overall carbon storage and control over water and nutrient flows. Restoring stable forest functions also requires multiple species. In particular in the light of global climatic change scenarios, which predict more frequent extreme disturbances and climatic events, it is important to incorporate insights from the relation between biodiversity and stability of ecosystem functioning into forest restoration projects. Rather than focussing on species per se, focussing on functional diversity of tree species assemblages seems appropriate when selecting tree species for restoration. Finally, also plant genetic diversity and above - below-ground linkages should be considered during the restoration process, as these likely have prominent but until now poorly understood effects at the level of the ecosystem. The BEF-approach provides a useful framework to evaluate forest restoration in an

  2. Heterogeneity of hemiboreal forests related to ecosystems functioning.

    Science.gov (United States)

    Krasnov, Dmitrii; Noe, Steffen M.; Krasnova, Alisa; Niinemets, Ülo

    2014-05-01

    Heterogeneity is one of the key components of sustainable development of every living system. Boreal and hemiboreal terrestrial systems have less biodiversity compared to tropical (or more southern). Heterogeneity provides the source for restocking of ecosystem living components, irregular distribution of nutrients, places for living (medium for living). Main components of forest horizontal heterogeneity are related to: horizontal distribution of dominant species, soil properties, topography and as natural as human disturbances. Soil as a main source for nutrient supply plays important role in the functioning of terrestrial ecosystems. The understanding of principles (regularity) of spatial distribution of such soil properties as soil acidity, available for living organisms nutrients, soil moisture and temperature, soil density and the role of tree dominant and co-dominate species can give deeper knowledge about ecosystem functioning. The models based on this knowledge can be more precise and give possibilities to predict behavior of ecosystem in terms of global climate change. The aim of the project is to assess spatial distribution and changing of soil properties related to spatial distribution of vegetation, microtopography and landscape position. The project was done in the frame of SMEAR Estonia.

  3. Insect pest management in forest ecosystems

    Science.gov (United States)

    Dahlsten, Donald L.; Rowney, David L.

    1983-01-01

    Understanding the role of insects in forest ecosystems is vital to the development of environmentally and economically sound pest management strategies in forestry Most of the research on forest insects has been confined to phytophagous species associated with economically important tree species The roles of most other insects in forest environments have generally been ignored, including the natural enemies and associates of phytophagous species identified as being important In the past few years several investigations have begun to reevaluate the role of phytophagous species responsible for perturbation in forest ecosystems, and it appears that these species may be playing an important role in the primary productivity of those ecosystems Also, there is an increasing awareness that forest pest managers have been treating the symptoms and not the causes of the problems in the forest Many insect problems are associated with poor sites or sites where trees are growing poorly because of crowding As a result, there is considerable emphasis on the hazard rating of stands of trees for their susceptibility to various phytophagous insects The next step is to manipulate forest stands to make them less susceptible to forest pest complexes A thinning study in California is used as an example and shows that tree mortality in ponderosa pine ( Pinus ponderosa) attributable to the western pine beetle ( Dendroctonus brevicomis) can be reduced by commercial thinning to reduce stocking

  4. 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...

  5. Restoring the Nitrogen Cycle in the Boreal Forest - a Case Study from Northern Alberta

    Science.gov (United States)

    Masse, Jacynthe; Grayston, Sue; Prescott, Cindy; Quideau, Sylvie

    2014-05-01

    The Athabasca oil sands deposit, located in the boreal forests of Northern Alberta, is one of the largest single oil deposits in the world. This deposit rests underneath 40,200 square kilometres of land. To date, an area of about 715 square kilometres has been disturbed by oil sands mining activity (Government of Alberta, 2013). Following surface mining, companies have the legal obligation to restore soil-like profiles that can support the previous land capabilities (Powter et al., 2012). Because of its importance for site productivity, re-establishment of the nitrogen cycle between these reconstructed soils and plants is one of the most critical factors required to insure long term sustainability of reclaimed boreal landscape. High nitrogen deposition recorded in the oil sands area combined with the high level of nitrate found in reclaimed soils raised concerns about the possibility of these reclaimed soils being in early stages of N saturation (Laxton et al 2010; Hemsley, 2012), although little evidence of net nitrification in these reclaimed soils suggests the contrary (Laxton et al. 2012). To date, results on the behaviour of the nitrogen cycle in the reclaimed sites are contradictory. A systematic study of the nitrogen cycle, and especially rates of gross mineralization, nitrification and denitrification, is needed. Our research aimed at 1) measuring the gross rates of nitrogen transformations under different vegetation treatments in both reclaimed and naturally-disturbed (fire) sites and 2) characterizing the microbial communities participating in the nitrogen cycle within the same soils. A series of 20 soils, covering different vegetation treatments (plots planted with aspen (Populus tremuloides), spruce (Picea glauca) and grassland) were investigated. Gross nitrogen transformation rates were measured using 15N pool-dilution (Müller et al. 2007). Microbial communities participating in the N-cycle were characterized using qPCR and pyrosequencing. Differences

  6. Nitrogen Alters Fungal Communities in Boreal Forest Soil: Implications for Carbon Cycling

    Science.gov (United States)

    Allison, S. D.; Treseder, K. K.

    2005-12-01

    One potential effect of climate change in high latitude ecosystems is to increase soil nutrient availability. In particular, greater nitrogen availability could impact decomposer communities and lead to altered rates of soil carbon cycling. Since fungi are the primary decomposers in many high-latitude ecosystems, we used molecular techniques and field surveys to test whether fungal communities and abundances differed in response to nitrogen fertilization in a boreal forest ecosystem. We predicted that fungi that degrade recalcitrant carbon would decline under nitrogen fertilization, while fungi that degrade labile carbon would increase, leading to no net change in rates of soil carbon mineralization. The molecular data showed that basidiomycete fungi dominate the active fungal community in both fertilized and unfertilized soils. However, we found that fertilization reduced peak mushroom biomass by 79%, although most of the responsive fungi were ectomycorrhizal and therefore their capacity to degrade soil carbon is uncertain. Fertilization increased the activity of the cellulose-degrading enzyme beta-glucosidase by 78%, while protease activity declined by 39% and polyphenol oxidase, a lignin-degrading enzyme, did not respond. Rates of soil respiration did not change in response to fertilization. These results suggest that increased nitrogen availability does alter the composition of the fungal community, and its potential to degrade different carbon compounds. However, these differences do not affect the total flux of CO2 from the soil, even though the contribution to CO2 respiration from different carbon pools may vary with fertilization. We conclude that in the short term, increased nitrogen availability due to climate warming or nitrogen deposition is more likely to alter the turnover of individual carbon pools rather than total carbon fluxes from the soil. Future work should determine if changes in fungal community structure and associated differences in

  7. 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.

  8. 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...

  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. 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...

  11. 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...

  12. Mountain pine beetle host-range expansion threatens the boreal forest.

    Science.gov (United States)

    Cullingham, Catherine I; Cooke, Janice E K; Dang, Sophie; Davis, Corey S; Cooke, Barry J; Coltman, David W

    2011-05-01

    The current epidemic of the mountain pine beetle (MPB), an indigenous pest of western North American pine, has resulted in significant losses of lodgepole pine. The leading edge has reached Alberta where forest composition shifts from lodgepole to jack pine through a hybrid zone. The susceptibility of jack pine to MPB is a major concern, but there has been no evidence of host-range expansion, in part due to the difficulty in distinguishing the parentals and their hybrids. We tested the utility of a panel of microsatellite loci optimized for both species to classify lodgepole pine, jack pine and their hybrids using simulated data. We were able to accurately classify simulated individuals, and hence applied these markers to identify the ancestry of attacked trees. Here we show for the first time successful MPB attack in natural jack pine stands at the leading edge of the epidemic. This once unsuitable habitat is now a novel environment for MPB to exploit, a potential risk which could be exacerbated by further climate change. The consequences of host-range expansion for the vast boreal ecosystem could be significant. PMID:21457381

  13. 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.

  14. 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...

  15. 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.

  16. 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.

  17. 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

  18. Radionuclide transport along a boreal hill slope - elevated soil water concentrations in riparian forest soils

    International Nuclear Information System (INIS)

    The transport of radionuclides from forest ecosystems and out into surface waters is a crucial process for understanding the long-term fate of radionuclides in the boreal landscape. Boreal forests are typically dominated by podzol soils, but the streams draining the forests are often lined by highly organic, often peat-like soils, which the radionuclides must pass through in order to reach the stream. This so-called riparian zone therefore represents a fundamentally different biogeochemical environment than ordinary forest soils, e.g. by exhibiting significantly lower pH and higher concentrations of organic colloids, which significantly can affect the mobility of many radionuclides. Since the riparian zone is the last terrestrial environment that the groundwater is in contact with before it enters the stream, previous research has demonstrated its profound impact on the stream water chemistry. Hence, the riparian soils should also be important for the transport and accumulation of radionuclides. Therefore, soil water was sampled using suction lysimeters installed at different depths along a 22 m long forested hill slope transect in northern Sweden, following the flow pathway of the groundwater from the uphill podzol to the riparian zone near the stream channel. The analyses included a wide range of hydrochemical parameters and many radiologically important elements, e.g. U, Th, Ni, C, Sr, Cs, REEs and Cl. The sampling was repeated ten times throughout a year in order to also capture the temporal variability of the soil water chemistry. The water chemistry of the investigated transect displayed a remarkable change as the groundwater approached the stream channel. Strongly increased concentrations of many elements were observed in the riparian soils. For instance, the concentrations of Th were more than 100 times higher than in the riparian zone than in the uphill forest, suggesting that the riparian zone may be a hotspot for radionuclide accumulation. The reason

  19. Radionuclide transport along a boreal hill slope - elevated soil water concentrations in riparian forest soils

    Energy Technology Data Exchange (ETDEWEB)

    Lidman, Fredrik; Boily, Aasa; Laudon, Hjalmar [Dept. of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umeaa (Sweden); Koehler, Stephan J. [Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, P.O. 7050, 750 07 Uppsala (Sweden)

    2014-07-01

    The transport of radionuclides from forest ecosystems and out into surface waters is a crucial process for understanding the long-term fate of radionuclides in the boreal landscape. Boreal forests are typically dominated by podzol soils, but the streams draining the forests are often lined by highly organic, often peat-like soils, which the radionuclides must pass through in order to reach the stream. This so-called riparian zone therefore represents a fundamentally different biogeochemical environment than ordinary forest soils, e.g. by exhibiting significantly lower pH and higher concentrations of organic colloids, which significantly can affect the mobility of many radionuclides. Since the riparian zone is the last terrestrial environment that the groundwater is in contact with before it enters the stream, previous research has demonstrated its profound impact on the stream water chemistry. Hence, the riparian soils should also be important for the transport and accumulation of radionuclides. Therefore, soil water was sampled using suction lysimeters installed at different depths along a 22 m long forested hill slope transect in northern Sweden, following the flow pathway of the groundwater from the uphill podzol to the riparian zone near the stream channel. The analyses included a wide range of hydrochemical parameters and many radiologically important elements, e.g. U, Th, Ni, C, Sr, Cs, REEs and Cl. The sampling was repeated ten times throughout a year in order to also capture the temporal variability of the soil water chemistry. The water chemistry of the investigated transect displayed a remarkable change as the groundwater approached the stream channel. Strongly increased concentrations of many elements were observed in the riparian soils. For instance, the concentrations of Th were more than 100 times higher than in the riparian zone than in the uphill forest, suggesting that the riparian zone may be a hotspot for radionuclide accumulation. The reason

  20. 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.

  1. Correlations between the Heterogeneity of Permafrost Thaw Depth and Vegetation in Boreal Forests and Arctic Tundra in Alaska.

    Science.gov (United States)

    Uy, K. L. Q.; Natali, S.; Kholodov, A. L.; Loranty, M. M.

    2015-12-01

    Global climate change induces rapid large scale changes in the far Northern regions of the globe, which include the thickening of the active layer of arctic and subarctic soils. Active layer depth, in turn, drives many changes to the hydrology and geochemistry of the soil, making an understanding of this layer essential to boreal forest and arctic tundra ecology. Because the structure of plant communities can affect the thermal attributes of the soil, they may drive variations in active layer depth. For instance, trees and tussocks create shade, which reduces temperatures, but also hold snow, which increases temperature through insulation; these aspects of vegetation can increase or decrease summer thaw. The goal of this project is to investigate correlations between the degree of heterogeneity of active layer depths, organic layer thickness, and aboveground vegetation to determine how these facets of Northern ecosystems interact at the ecosystem scale. Permafrost thaw and organic layer depths were measured along 20m transects in twenty-four boreal forest and tundra sites in Alaska. Aboveground vegetation along these transects was characterized by measuring tree diameter at breast height (DBH), tussock dimensions, and understory biomass. Using the coefficient of variation as a measure of heterogeneity, we found a positive correlation between thaw depth variability and tussock volume variability, but little correlation between the former and tree DBH variability. Soil organic layer depth variability was also positively correlated with thaw depth variability, but weakly correlated with tree and tussock heterogeneity. These data suggest that low vegetation and organic layer control the degree of variability in permafrost thaw at the ecosystem scale. Vegetation can thus affect the microtopography of permafrost and future changes in the plant community that affect vegetation heterogeneity will drive corresponding changes in the variability of the soil.

  2. Effects of Repeated Fires in the Forest Ecosystems of the Zabaikalye Region, Southern Siberia

    Science.gov (United States)

    Kukavskaya, E.; Buryak, L. V.; Conard, S. G.; Petkov, A.; Barrett, K.; Kalenskaya, O. P.; Ivanova, G.

    2014-12-01

    Fire is the main ecological disturbance controlling forest development in the boreal forests of Siberia and contributing substantially to the global carbon cycle. The warmer and dryer climate observed recently in the boreal forests is considered to be responsible for extreme fire weather, resulting in higher fire frequency, larger areas burned, and an increase of fire severity. Because of the increase of fire activity, boreal forests in some regions may not be able to reach maturity before they re-burn, which means less carbon will be stored in the ecosystem and more will remain in the atmosphere. Moreover, if one fire occurs within a few years of another, some stands will not re-grow at all, and even more carbon will accumulate in the atmosphere. Zabaikalye region located in the south of Siberia is characterized by the highest fire activity in Russia. With a use of the satellite-based fire product we found that there are about 7.0 million hectares in the region burned repeatedly during the last decade. We have investigated a number of sites in-situ in light-coniferous (Scots pine and larch) forests and evaluated the impacts of repeated fires on fuel loads, carbon emissions, and tree regeneration. Substantial decrease of carbon stocks, change of the vegetation structure and composition, and soil erosion were observed in many areas disturbed by repeated fires. At drier sites located in the southern regions repeated fires prohibited successful regeneration and resulted in forest conversion to grassland. Detection and monitoring of changes in the areas of Siberia where repeated fires have caused a major shift in ecosystem structure and function is required for the development of sustainable forest management strategies to mitigate climate change. The research was supported by NASA LCLUC Program.

  3. Silvicultural management in maintaining biodiversity and resistance of forests in Europe-boreal zone: case Finland.

    Science.gov (United States)

    Mielikäinen, Kari; Hynynen, Jari

    2003-01-01

    The majority of untouched natural boreal forests have been regenerated through large catastrophes, occurring by intervals between 50 and 100 years. Storm and fire will open the landscape, result in a huge amount of dead or dying trees and let the pioneer tree species germinate. These processes are the guideline for Finnish forest management today. The main focus by maintaining the biodiversity in Finnish boreal forest zone is directed to managed forests. Nature-orientated silviculture on stand level is practised. The site type classification, a reflection of the modern concept of biodiversity and developed by Cajander early in 1900s, on the basis of natural vegetation composition of the site, has the central role by choosing tree species, regeneration methods and thinning procedure, and reflects also on the site productivity. The small size of stands, the abundance of natural seedlings in planted stands and the popularity of mixed stands have a positive impact on biodiversity of forests. The protection of small-sized valuable habitats in commercially managed stands, the leaving of retention trees standing and lying in the forest in all phases of the rotation, are activities made for biodiversity. Many insects and fungi are adapted to catastrophes and so they can survive in single stems left on regeneration areas. Maintaining the biodiversity in multifunctional forests is also supported by the new forest legislation and by the criteria of Finnish Forest Certification System. PMID:12659803

  4. 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...

  5. Neighbourhood-scale urban forest ecosystem classification.

    Science.gov (United States)

    Steenberg, James W N; Millward, Andrew A; Duinker, Peter N; Nowak, David J; Robinson, Pamela J

    2015-11-01

    Urban forests are now recognized as essential components of sustainable cities, but there remains uncertainty concerning how to stratify and classify urban landscapes into units of ecological significance at spatial scales appropriate for management. Ecosystem classification is an approach that entails quantifying the social and ecological processes that shape ecosystem conditions into logical and relatively homogeneous management units, making the potential for ecosystem-based decision support available to urban planners. The purpose of this study is to develop and propose a framework for urban forest ecosystem classification (UFEC). The multifactor framework integrates 12 ecosystem components that characterize the biophysical landscape, built environment, and human population. This framework is then applied at the neighbourhood scale in Toronto, Canada, using hierarchical cluster analysis. The analysis used 27 spatially-explicit variables to quantify the ecosystem components in Toronto. Twelve ecosystem classes were identified in this UFEC application. Across the ecosystem classes, tree canopy cover was positively related to economic wealth, especially income. However, education levels and homeownership were occasionally inconsistent with the expected positive relationship with canopy cover. Open green space and stocking had variable relationships with economic wealth and were more closely related to population density, building intensity, and land use. The UFEC can provide ecosystem-based information for greening initiatives, tree planting, and the maintenance of the existing canopy. Moreover, its use has the potential to inform the prioritization of limited municipal resources according to ecological conditions and to concerns of social equity in the access to nature and distribution of ecosystem service supply. PMID:26311086

  6. 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.

  7. 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

  8. Sensitivity of the boreal forest-mire ecotone CO2, CH4, and N2O global warming potential to rainy and dry weather

    Science.gov (United States)

    Ťupek, Boris; Minkkinen, Kari; Vesala, Timo; Nikinmaa, Eero

    2015-04-01

    In a mosaic of well drained forests and poorly drained mires of boreal landscape the weather events such as drought and rainy control greenhouse gas dynamics and ecosystem global warming potential (GWP). In forest-mire ecotone especially in ecosystems where CO2 sink is nearly balanced with CO2 source, it's fairly unknown whether the net warming effect of emissions of gases with strong radiative forcing (CH4 and N2O) could offset the net cooling effect of CO2 sequestration. We compared the net ecosystem CO2 exchange (NEE) estimated from the carbon sequestrations of forest stands and forest floor CO2 fluxes against CH4 and N2O fluxes of nine forest/mire site types along the soil moisture gradient in Finland. The ground water of nine sites changed between 10 m in upland forests and 0.1 m in mires, and weather during three years ranged between exceptionally wet and dry for the local climate. The NEE of upland forests was typically a sink of CO2, regardless the weather. Though, xeric pine forest was estimated to be a source of CO2 during wet and intermediate year and became a weak sink only in dry year. The NEE of forest-mire transitions ranged between a sink in dry year, while increased stand carbon sequestration could offset the reduced forest floor CO2 emission, and a source in wet year. The NEE of two sparsely forested mires strongly differed. The lawn type mire was balanced around zero and the hummock type mire was relatively strong NEE sink, regardless the weather. Generally, nearly zero N2O emission could not offset the cooling effect of net CH4 sink and net CO2 sink of upland forest and forest-mire transitions. However in sparsely forested mires, with N2O emission also nearly zero, the CH4 emission during wet and intermediate year played important role in turning the net cooling effect of NEE into a net warming. When evaluating GWP of boreal landscapes, undisturbed forest-mire transitions should be regarded as net cooling ecosystems instead of hotspots of net

  9. Photosynthetic properties of boreal bog plant species and their contribution to ecosystem level carbon sink

    Science.gov (United States)

    Korrensalo, Aino; Hájek, Tomas; Alekseychik, Pavel; Rinne, Janne; Vesala, Timo; Mehtätalo, Lauri; Mammarella, Ivan; Tuittila, Eeva-Stiina

    2016-04-01

    Boreal bogs have a low number of plant species, but a large diversity of growth forms. This heterogeneity might explain the seasonally less varying photosynthetic productivity of these ecosystems compared to peatlands with vegetation consisting of fewer growth forms. The differences in photosynthetic properties within bog species and phases of growing season has not been comprehensively studied. Also the role of different plant species for the ecosystem level carbon (C) sink function is insufficiently known. We quantified the seasonal variation of photosynthetic properties in bog plant species and assessed how this variation accounts for the temporal variation in the ecosystem C sink. Photosynthetic light response of 11 vascular plant and 8 Sphagnum moss species was measured monthly over the growing season of 2013. Based on the species' light response parameters, leaf area development and areal coverage, we estimated the ecosystem level gross photosynthesis rate (PG) over the growing season. The level of upscaled PG was verified by comparing it to the ecosystem gross primary production (GPP) estimate calculated based on eddy covariance (EC) measurements. Although photosynthetic parameters differed within plant species and months, these differences were of less importance than expected for the variation in ecosystem level C sink. The most productive plant species at the ecosystem scale were not those with the highest maximum potential photosynthesis per unit of leaf area (Pmax), but those having the largest areal coverage. Sphagnum mosses had 35% smaller Pmax than vascular plants, but had higher photosynthesis at the ecosystem scale throughout the growing season. The contribution of the bog plant species to the ecosystem level PG differed over the growing season. The seasonal variation in ecosystem C sink was mainly controlled by phenology. Sedge PG had a sharp mid-summer peak, but the PG of evergreen shrubs and Sphagna remained rather stable over the growing season

  10. Fire in Western Forest Ecosystems

    OpenAIRE

    Arno, Stephen F

    2000-01-01

    Major forest types that are characterized by nonlethal understory fire regimes include those where ponderosa pine or Jeffrey pine has been a major component either as a fire-maintained seral type or as the self-perpetuating climax (table 5-1). This includes extensive areas throughout the Western United States from northern Mexico to southern British Columbia, Canada (Little 1971). Also, sizeable areas of open woodlands dominated by Oregon white oak, California black oak, blue oak, or Digger p...

  11. Significant increase in ecosystem C can be achieved with sustainable forest management in subtropical plantation forests.

    Science.gov (United States)

    Wei, Xiaohua; Blanco, Juan A

    2014-01-01

    Subtropical planted forests are rapidly expanding. They are traditionally managed for intensive, short-term goals that often lead to long-term yield decline and reduced carbon sequestration capacity. Here we show how it is possible to increase and sustain carbon stored in subtropical forest plantations if management is switched towards more sustainable forestry. We first conducted a literature review to explore possible management factors that contribute to the potentials in ecosystem C in tropical and subtropical plantations. We found that broadleaves plantations have significantly higher ecosystem C than conifer plantations. In addition, ecosystem C increases with plantation age, and reaches a peak with intermediate stand densities of 1500-2500 trees ha⁻¹. We then used the FORECAST model to simulate the regional implications of switching from traditional to sustainable management regimes, using Chinese fir (Cunninghamia lanceolata) plantations in subtropical China as a study case. We randomly simulated 200 traditional short-rotation pure stands and 200 sustainably-managed mixed Chinese fir--Phoebe bournei plantations, for 120 years. Our results showed that mixed, sustainably-managed plantations have on average 67.5% more ecosystem C than traditional pure conifer plantations. If all pure plantations were gradually transformed into mixed plantations during the next 10 years, carbon stocks could rise in 2050 by 260.22 TgC in east-central China. Assuming similar differences for temperate and boreal plantations, if sustainable forestry practices were applied to all new forest plantation types in China, stored carbon could increase by 1,482.80 TgC in 2050. Such an increase would be equivalent to a yearly sequestration rate of 40.08 TgC yr⁻¹, offsetting 1.9% of China's annual emissions in 2010. More importantly, this C increase can be sustained in the long term through the maintenance of higher amounts of soil organic carbon and the production of timber products

  12. 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.

  13. Radioactive caesium in Boreal forest landscapes - Dynamics and transport in food webs. Summary of research 1986-1996

    International Nuclear Information System (INIS)

    The need for - but also the paucity of - radioecological knowledge concerning the boreal forest became particularly apparent after the nuclear power plant accident in Chernobyl in April 1986. As a consequence several new projects were initiated in the Nordic countries with particular focus on the behaviour of radioactive caesium in terrestrial and aquatic systems characteristic for the Fenno-Scandinavian landscapes. Among these new projects a multi-disciplinary co-operation in Umeaa between scientists at the Swedish University of Agricultural Sciences, and the Defence Research Establishment emerged. Initially this joint work focused mainly on descriptions of the dynamic changes of the content of radioactive caesium in soil-plant and animal communities in the county of Vaesterbotten. Most of the studies have been performed at the Vindeln experimental forest, 60 km NW of Umeaa. Plants of key interest were: bilberry (Vaccinium myrtillus), birch (Betula spp.), and pine (Pinus sylvestris), and among the animals: the moose (Alces alces) and a small rodent, the forest vole (Clethrionomus glareolus). Gradually over the past ten years the research has entered the stage where the specific causes of the caesium behaviour have been addressed - partly by the help of models developed for simulating forest ecosystems, partly by complementary field experiments. This paper reviews our main findings on this theme concerning the behaviour of radioactive caesium in boreal landscapes and significant pathways to man, as has become apparent from the radioecological co-operation dating from about ten years back. A list of the publications arising from these studies since 1986 is also presented in this report

  14. Radioactive caesium in Boreal forest landscapes - Dynamics and transport in food webs. Summary of research 1986-1996

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, R.; Nylen, T.; Palo, T

    1998-12-01

    The need for - but also the paucity of - radioecological knowledge concerning the boreal forest became particularly apparent after the nuclear power plant accident in Chernobyl in April 1986. As a consequence several new projects were initiated in the Nordic countries with particular focus on the behaviour of radioactivecaesium in terrestrial and aquatic systems characteristic for the Fenno-Scandinavian landscapes. Among these new projects a multi-disciplinary co-operation in Umeaa between scientists at the Swedish University of Agricultural Sciences, and the Defence Research Establishment emerged. Initially this joint work focused mainly on descriptions of the dynamic changes of the content of radioactive caesium in soil-plant and animal communities in the county of Vaesterbotten. Most of the studies have been performed at the Vindeln experimental forest, 60 km NW of Umeaa. Plants of key interest were: bilberry (Vaccinium myrtillus), birch (Betula spp.), and pine (Pinus sylvestris), and among the animals: the moose (Alces alces) and a small rodent, the forest vole (Clethrionomus glareolus). Gradually over the past ten years the research has entered the stage where the specific causes of the caesium behaviour have been addressed - partly by the help of models developed for simulating forest ecosystems, partly by complementary field experiments. This paper reviews our main findings on this theme concerning the behaviour of radioactive caesium in boreal landscapes and significant pathways to man, as has become apparent from the radioecological co-operation dating from about ten years back. A list of the publications arising from these studies since 1986 is also presented in this report.

  15. Forest and land inventory using ERTS imagery and aerial photography in the boreal forest region of Alberta, Canada

    Science.gov (United States)

    Kirby, C. L.

    1974-01-01

    Satellite imagery and small-scale (1:120,000) infrared ektachrome aerial photography for the development of improved forest and land inventory techniques in the boreal forest region are presented to demonstrate spectral signatures and their application. The forest is predominately mixed, stands of white spruce and poplar, with some pure stands of black spruce, pine and large areas of poorly drained land with peat and sedge type muskegs. This work is part of coordinated program to evaluate ERTS imagery by the Canadian Forestry Service.

  16. 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

  17. Variations in the fire regime in the North American boreal forest between 1990 and 2004 and their potential impacts on terrestrial carbon storage

    Science.gov (United States)

    Kasischke, E. S.; Turetsky, M. R.; McGuire, A. D.; French, N. H.

    2004-12-01

    Fires in the North American boreal region play an important role in regulating the the levels of carbon stored in the terrestrial ecosystems of this region, both directly and indirectly. Biomass burning not only consumes carbon present in the aboveground vegetation and litter layers of boreal forests and peatlands (as is common during fires in temperate and tropical ecosystems), but also large amounts of carbon present in the organic layer that lies on top of mineral soil (consisting of moss, lichen, dead woody debris and organic soil). Understanding the factors controlling consumption of ground-layer organic matter during fires in boreal ecosystem is central to quantifying the terrestrial carbon budget in this region. The 1950-2004 period can be divided into 3 distinct epochs in terms of fire activity in the North American boreal region. The early epoch of 1950-1968 experienced the lowest fire activity, 1.2 million ha or Mha per yr, and increased to 2.1 Mha per yr during 1969-1986 epoch and 3.0 Mha per yr during 1987-2004 epoch. The end result of this steep rise in fire activity is an increase in the average amount of carbon released during fires. A key question that needs to be addressed is how much carbon has actually been released through the burning of ground-layer organic matter. The observed increases in average area burned are due to a combination of increases in the frequency of large fire years, as well as increases in average area burned during large fire years. Analyses of fire databases show that as the burned area increases during a given year, the percent of area burned in large fire events increases as well. The amount of fires occurring later in the growing season also increases. Recent and ongoing studies have integrated field observations with satellite observations on fire location and fire severity to provide more detailed assessments of how fires impact carbon budgets of boreal systems. These studies, along with theoretical models, indicate

  18. 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

  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. Experimental manipulation of a forest ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Beier, C.; Rasmussen, L.; Hansen, K. (eds.)

    1991-04-01

    The report describes the scientific research activities at the Klosterhede research site, Lemvig, West Jutland, Denmark. The site was selected as being located on the most sensitive soil type in Denmark with respect to potential soil acidification, as a permanent observation plot. From including descriptions of the biochemical cycling and ion balances of the forest ecosystem the research has been extended to include manipulations of the water and element fluxes of the ecosystem by means of a roof construction for removal of the atmospheric inputs of strong acids to the soil. A brief overview describes the applied methods and instrumentation, the general objectives, the hypotheses to be tested and the measuring programmes in addition to a description of the site and environmental conditions. Currently, it is considered that forest decline is a multifactoral problem caused by a combined stress on the trees from air pollution, climate, forest management, biological and abiotic influences etc. The project attempts to assess the importance of the various factors contributing to the total stress on the ecosystem. At the Klosterhede site the aim is to test some of the hypotheses by creating different research plots within the same research stand and site, thus ensuring that all soil and climatic factors are comparable whilst different manipulations of the biochemical cycles of the ecosystem are performed. The investigations, which cover nitrogen circulation, denitrification, ecophysiological activity, ectomycorrhiza and fertilization, susceptibility to insect attacks, microbial decomposition etc. are described in detail. (AB) (67 refs.).

  1. 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.

  2. Water, Energy and Carbon Balance Research: Recovery Trajectories For Oil Sands Reclamation and Disturbed Watersheds in the Western Boreal Forest

    Science.gov (United States)

    Petrone, R. M.; Carey, S. K.

    2014-12-01

    The Oil Sand Region (OSR) of North-Central Alberta exists within the sub-humid Boreal Plains (BP) ecozone, with a slight long-term moisture deficit regime. Despite this deficit, the BP is comprised of productive wetland and mixed wood (aspen and conifer dominated) forests. Reclamation activities are now underway at a large number of surface mining operations in the OSR, where target ecosystems are identified, soil prescriptions placed and commercial forest species planted. Some watersheds have been created that now contain wetlands. However, recent work in the BP suggests that over time wetlands supply moisture for the productivity of upland forests. Thus, water use of reclaimed forests is going to be critical in determining the sustainability of these systems and adjacent wetlands, and whether in time, either will achieve some form of equivalent capability that will allow for certification by regulators. A critical component in the success of any reclamation is that sufficient water is available to support target ecosystems through the course of natural climate cycles in the region. Water Use Efficiency (WUE), which links photosynthesis (GEP) with water use (Evapotranspiration (ET)), provides a useful metric to compare ecosystems and evaluate their utilization of resources. In this study, 41 site years of total growing season water and carbon flux data over 8 sites (4 reclamation, 4 regeneration) were evaluated using eddy covariance micrometeorological towers. WUE shows clear discrimination among ecosystem types as aspen stands assimilate more carbon per unit weight of water than conifers. WUEs also change with time as ecosystems become more effective at transpiring water through plant pathways compared with bare-soil evaporation, which allows an assessment of ability to limit water loss without carbon uptake. In addition, clonal rooting systems allow aspen forests to recover quicker after disturbance than reclamation sites in terms of their WUE. For reclamation

  3. Geographical gradients in boreal forest albedo and structure in Finland

    OpenAIRE

    Lukes, Petr; Rautiainen, Miina; Manninen, Terhikki; Stenberg, Pauline; Mottus, Matti

    2014-01-01

    Land surface albedo is an essential climate variable controlling the planetary radiative energy budget, yet it is still among the main uncertainties of the radiation budget in the current climate modeling. To date, albedo satellite products have not been linked to extensive forest inventory data sets due to the lack of ground reference data. Here, we used comprehensive and detailed maps of forest inventory variables to couple forest structure and MODIS albedo products for both winter and summ...

  4. Mechanisms of population declines in boreal forest grouse

    OpenAIRE

    Ludwig, Gilbert

    2007-01-01

    Populations of Finnish forest grouse have been declining during several decades. Using large data sets on both the individual and the population level, I have studied possible mechanisms and processes underlying the long-term declines of forest grouse in Finland. The observed decline in population size of Finnish forest grouse is most likely mediated through long-term changes in breeding success. The likely mechanisms underlying the long-term decrease in breeding success and population size i...

  5. 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

  6. Cryptic Methane Emissions from Upland Forest Ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Megonigal, Patrick [Smithsonian Institution, Washington, DC (United States); Pitz, Scott [Johns Hopkins Univ., Baltimore, MD (United States); Smithsonian Institution, Washington, DC (United States)

    2016-04-19

    This exploratory research on Cryptic Methane Emissions from Upland Forest Ecosystems was motivated by evidence that upland ecosystems emit 36% as much methane to the atmosphere as global wetlands, yet we knew almost nothing about this source. The long-term objective was to refine Earth system models by quantifying methane emissions from upland forests, and elucidate the biogeochemical processes that govern upland methane emissions. The immediate objectives of the grant were to: (i) test the emerging paradigm that upland trees unexpectedly transpire methane, (ii) test the basic biogeochemical assumptions of an existing global model of upland methane emissions, and (iii) develop the suite of biogeochemical approaches that will be needed to advance research on upland methane emissions. We instrumented a temperate forest system in order to explore the processes that govern upland methane emissions. We demonstrated that methane is emitted from the stems of dominant tree species in temperate upland forests. Tree emissions occurred throughout the growing season, while soils adjacent to the trees consumed methane simultaneously, challenging the concept that forests are uniform sinks of methane. High frequency measurements revealed diurnal cycling in the rate of methane emissions, pointing to soils as the methane source and transpiration as the most likely pathway for methane transport. We propose the forests are smaller methane sinks than previously estimated due to stem emissions. Stem emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration, resolving differences between models and measurements. The methods we used can be effectively implemented in order to determine if the phenomenon is widespread.

  7. Forest ecosystem and mining activity

    International Nuclear Information System (INIS)

    The Indian sub-continent has a tremendous diversity of plant and animal species. About 80,000 species of animals and 15,000 species of flowering plants have so far been described from India. Profound changes have taken place in this era, the changes driven by an unprecedented level of human demands for the resources. One major crisis is the loss of biological diversity. Tropical moist forest tracts harbouring the bulk of this diversity is of main concern. Many countries largely from tropical belts have been identified as megadiversity countries, for biodiversity conservation. India is one of them. Conserving India's heritage of biodiversity is a great challenge, with large biomass needs of its huge rural population and exploding resource demands of its growing urban-industrial-intensive agricultural sector. One such major impact on the biological diversity is mining. Main environmental problems of mining are deforestation, land damage, visual intrusion, and disturbance of hydrological systems. Opencast mining, specially with multi-seam or steep deposits involves creation of external overburden dumps which destroys further lands and causes visual intrusion. The present paper highlights a few case studies carried out to understand the biological environmental impact assessment due to mining activity and also discusses the management plan for eco-restoration of the mined areas and degraded lands. 3 refs., 4 figs., 4 tabs

  8. Challenges for understanding the combined impacts of climate change and the 2001-2010 fires on carbon cycling in Alaskan boreal forests (Invited)

    Science.gov (United States)

    Kasischke, E. S.; Alexander, H. D.; Barrett, K.; Genet, H.; Goetz, S. J.; Harden, J. W.; Hoy, E.; Johnstone, J. F.; Jorgenson, T.; Kane, E. S.; Kavenskiy, M.; Mack, M. C.; McGuire, A. D.; Mitchell, S. R.; O'Donnell, J. A.; Turetsky, M.

    2013-12-01

    During the 2000s, Alaska's boreal forest experienced more wildland fire than any decade in recorded history (since 1940). Examination of charcoal data suggests that the level of burning over the past decade surpasses that observed over the past 10,000 years in the Yukon River Flats(Kelly et al. 2013). Here, we will review recent research directed towards understanding how fire and climate interact to control carbon cycling in Alaska's boreal forest. In particular, we will focus on fire-climate-permafrost-ecosystem interactions as the key drivers of changes to carbon cycling in this biome. Topics covered in this presentation will include: (a) recent changes to Alaska's fire regime; (b) factors controlling the burning of surface organic layers in Alaskan boreal forests; (c) factors controlling changes in permafrost following fire; (d) how variations in fire severity and changes in permafrost control patterns of tree seedling recruitment and growth; and (e) integrated assessments (including modeling) of the impacts of these processes on carbon cycling. Reference: Kelly, R. et al. PNAS, doi/10.1073/ pnas.1305069110, 2013.

  9. 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...

  10. 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

  11. 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)...

  12. 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...

  13. 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...

  14. 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

  15. 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...

  16. 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

  17. Winter soil CO2 efflux in two contrasting forest ecosystems on the eastern Tibetan Plateau, China

    Institute of Scientific and Technical Information of China (English)

    Zhenfeng Xu; Feifei Zhou; Huajun Yin; Qing Liu

    2015-01-01

    Significant CO2 fluxes from snow-covered soils occur in cold biomes. However, little is known about winter soil respiration on the eastern Tibetan Plateau of China. We therefore measured winter soil CO2 fluxes and estimated annual soil respiration in two contrasting coniferous forest ecosystems (a Picea asperata plantation and a natural forest). Mean winter soil CO2 effluxes were 1.08 lmol m-2 s-1 in the plantation and 1.16 lmol m-2 s-1 in the natural forest. These values are higher than most reported winter soil CO2 efflux values for temperate or boreal forest ecosystems. Winter soil respiration rates were similar for our two forest ecosystems but mean soil CO2 efflux over the growing season was higher in the natural forest than in the plantation. The estimated winter and annual soil effluxes for the natural forest were 176.3 and 1070.3 g m-2, respectively, based on the relationship between soil respiration and soil temperature, which were 17.2 and 9.7 % greater than their counterparts in the plantation. The contributions of winter soil respiration to annual soil efflux were 15.4 % for the plantation and 16.5 % for the natural forest and were statistically similar. Our results indicate that winter soil CO2 efflux from frozen soils in the alpine coniferous forest ecosystems of the eastern Tibetan Plateau was considerable and was an important component of annual soil respiration. Moreover, reforestation (natural coniferous forests were deforested and reforested with P. asperata plantation) may reduce soil respiration by reducing soil carbon substrate availability and input.

  18. Dissolved organic carbon in Alaskan boreal forest: Sources, chemical characteristics, and biodegradability

    Science.gov (United States)

    Wickland, K.P.; Neff, J.C.; Aiken, G.R.

    2007-01-01

    The fate of terrestrially-derived dissolved organic carbon (DOC) is important to carbon (C) cycling in both terrestrial and aquatic environments, and recent evidence suggests that climate warming is influencing DOC dynamics in northern ecosystems. To understand what determines the fate of terrestrial DOC, it is essential to quantify the chemical nature and potential biodegradability of this DOC. We examined DOC chemical characteristics and biodegradability collected from soil pore waters and dominant vegetation species in four boreal black spruce forest sites in Alaska spanning a range of hydrologic regimes and permafrost extents (Well Drained, Moderately Well Drained, Poorly Drained, and Thermokarst Wetlands). DOC chemistry was characterized using fractionation, UV-Vis absorbance, and fluorescence measurements. Potential biodegradability was assessed by incubating the samples and measuring CO2 production over 1 month. Soil pore water DOC from all sites was dominated by hydrophobic acids and was highly aromatic, whereas the chemical composition of vegetation leachate DOC varied significantly with species. There was no seasonal variability in soil pore water DOC chemical characteristics or biodegradability; however, DOC collected from the Poorly Drained site was significantly less biodegradable than DOC from the other three sites (6% loss vs. 13-15% loss). The biodegradability of vegetation-derived DOC ranged from 10 to 90% loss, and was strongly correlated with hydrophilic DOC content. Vegetation such as Sphagnum moss and feathermosses yielded DOC that was quickly metabolized and respired. In contrast, the DOC leached from vegetation such as black spruce was moderately recalcitrant. Changes in DOC chemical characteristics that occurred during microbial metabolism of DOC were quantified using fractionation and fluorescence. The chemical characteristics and biodegradability of DOC in soil pore waters were most similar to the moderately recalcitrant vegetation

  19. Moss and soil contributions to the annual net carbon flux of a maturing boreal forest

    Science.gov (United States)

    Harden, J.W.; O'Neill, K. P.; Trumbore, S.E.; Veldhuis, H.; Stocks, B.J.

    1997-01-01

    We used input and decomposition data from 14C studies of soils to determine rates of vertical accumulation of moss combined with carbon storage inventories on a sequence of burns to model how carbon accumulates in soils and moss after a stand-killing fire. We used soil drainage - moss associations and soil drainage maps of the old black spruce (OBS) site at the BOREAS northern study area (NSA) to areally weight the contributions of each moderately well drained, feathermoss areas; poorly drained sphagnum - feathermoss areas; and very poorly drained brown moss areas to the carbon storage and flux at the OBS NSA site. On this very old (117 years) complex of black spruce, sphagnum bog veneer, and fen systems we conclude that these systems are likely sequestering 0.01-0.03 kg C m-2 yr-' at OBS-NSA today. Soil drainage in boreal forests near Thompson, Manitoba, controls carbon storage and flux by controlling moss input and decomposition rates and by controlling through fire the amount and quality of carbon left after burning. On poorly drained soils rich in sphagnum moss, net accumulation and long-term storage of carbon is higher than on better drained soils colonized by feathermosses. The carbon flux of these contrasting ecosystems is best characterized by soil drainage class and stand age, where stands recently burned are net sources of CO2, and maturing stands become increasingly stronger sinks of atmospheric CO2. This approach to measuring carbon storage and flux presents a method of scaling to larger areas using soil drainage, moss cover, and stand age information.

  20. Fire as an agent in redistributing fallout 137Cs in the Canadian boreal forest

    International Nuclear Information System (INIS)

    The presence of fallout 137Cs in the boreal forest and the effect of fire in redistributing 137Cs were studied in the remote region of Wood Buffalo National Park, N.W.T., Canada. Results of a preliminary study of five burned (the fire occurred in 1981) and five unburned stands conducted in 1986 revealed that 137Cs concentrations were higher in the surface soil of the burned stands than in the unburned ones. In 1989, a comprehensive study was conducted, in which one burned and one unburned white spruce stand were sampled in greater detail. The latter investigation also revealed a difference in the distribution of 137Cs within the burned stand compared to the unburned one. Specifically, in the unburned stand, the highest 137Cs concentration was identified in the epiphytic lichens and in the mosses, whereas in the burned stand, the highest concentration was measured in the surface organic soil. These results indicate that fire caused the mobilization of part of the 137Cs bound to the above-ground matter and concentrated it in the ash layer of the burned surface soil. An additional ecologically important finding in our study was that significantly lower total 137Cs load was observed in the burned stand compared to the unburned one. Hence, our data not only provide evidence that 137Cs is being redistributed within the burned stand to the surface soil, but also that part of the 137Cs is lost due to fire, presumably contaminating other ecosystems. Volatilization and fly-ash during the fire, and runoff (e.g. from snow melt) after the fire are the most likely mechanisms for the 137Cs removal. These findings point to fire as an agent of 137Cs secondary contamination for initially unaffected systems, as well as for those previously contaminated

  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?

    Directory of Open Access Journals (Sweden)

    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. 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)

  3. Cycling of radiocesium in forest ecosystems

    International Nuclear Information System (INIS)

    The behaviour of 137 Cs in forest ecosystems following an atmospheric contamination presents certain peculiarities which make these ecosystems an important compartment to consider in the framework of the protection of man and populations. Among these properties, the very high filtering capacity of the forest cover and the increased deposition velocities justify a higher contamination level of the forest green surfaces after an atmospheric release. In these conditions the forest management thus requires a good understanding of the cycle of the deposited radiocesium. To a certain extent comparing the behaviour of K that may be analogous to Cs may help the radioecologist in its understanding of the 137 Cs behaviour. Such a conclusion may also be drawn for other radionuclides and we surely have to regret that the mineral nutrition principles are often ignored in radioecology. The results of the observations in field and controlled conditions which are described in this paper are in favor of a good analogy between these two elements as soon as they are cycling in the plant

  4. 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

  5. Microbial community response to permafrost thaw after wildfire in an Alaskan upland boreal forest

    Science.gov (United States)

    Tas, N.; Jorgenson, M. T.; Wang, S.; Berhe, A. A.; Wickland, K. P.; Waldrop, M. P.; Jansson, J. K.

    2012-12-01

    Fire is a major factor controlling the long-term dynamics of soil carbon in Alaskan boreal forests. Wildfire not only contributes to a significant global emission of greenhouse gasses but also can indirectly result in the deepening of the active layer and thawing of near-surface permafrost due to reductions in organic layer depth and increases in heat flux through soil. Although boreal ecosystems are fire-adapted, increased fire frequency and rising global temperatures may result in warmer soils and therefore increase the metabolic rates of decomposer microbes and result in accelerated permafrost decomposition and greenhouse gas fluxes. In addition to fire-mediated changes in soil and vegetation structure, changes in the soil microbial community structure are likely to have consequences for rates of soil carbon cycling. In this study we aimed to define the impact of fire on soil microbial communities in an upland black spruce forest and to assess microbial metabolic potential for soil respiration, methanogenesis, and nitrous oxide (N2O) flux. Soil samples from two fire impacted and three control (unburned) locations were collected near Nome Creek, AK, an upland moderately drained black spruce forest. This location was within the Boundary fire that burned between mid-June and the end of August 2004. Soil temperature measurements from before and after the fire showed that soils were warmer after the fire event and the permafrost thawed below 1m. At each sampling location, soil and permafrost samples were collected every 10 cm to a depth of 1 m. Besides biochemical characterization, CO2, CH4, N2O fluxes and potential activities of enzymes involved in extracellular decomposition of complex organic molecules (hemicellulose, chitin and lignin) were measured. The microbial community composition in the samples was determined by sequencing of 16S rRNA genes and microbial metabolic potential was assessed via sequencing of total genomic DNA (metagenomics) in selected active

  6. Light-induced diurnal pattern of methane exchange in a boreal forest

    Science.gov (United States)

    Sundqvist, Elin; Crill, Patrick; Mölder, Meelis; Vestin, Patrik; Lindroth, Anders

    2013-04-01

    Boreal forests represents one third of the Earth's forested land surface area and is a net sink of methane and an important component of the atmospheric methane budget. Methane is oxidized in well-aerated forest soils whereas ponds and bog soils are sources of methane. Besides the microbial processes in the soil also forest vegetation might contribute to methane exchange. Due to a recent finding of methane consumption by boreal plants that correlated with photosynthetic active radiation (PAR), we investigate the impact of PAR on soil methane exchange at vegetated plots on the forest floor. The study site, Norunda in central Sweden, is a 120 years old boreal forest stand, dominated by Scots pine and Norway spruce. We used continuous chamber measurements in combination with a high precision laser gas analyzer (Los Gatos Research), to measure the methane exchange at four different plots in July-November 2009, and April-June 2010. The ground vegetation consisted almost entirely of mosses and blueberry-shrubs. Two of the plots acted as stable sinks of methane whereas the other two plots shifted from sinks to sources during very wet periods. The preliminary results show a clear diurnal pattern of the methane exchange during the growing season, which cannot be explained by temperature. The highest consumption occurs at high PAR levels. The amplitude of the diurnal methane exchange during the growing season is in the order of 10 μmol m-2 h-1. This indicates that besides methane oxidation by methanotrophs in the soil there is an additional removal of methane at soil level by a process related to ground vegetation.

  7. 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

  8. Land cover mapping, fire regeneration, and scaling studies in the Canadian boreal forest with 1 km AVHRR and Landsat TM data

    Science.gov (United States)

    Steyaert, L. T.; Hall, F. G.; Loveland, T. R.

    1997-12-01

    A multitemporal 1 km advanced very high resolution radiometer (AVHRR) land cover analysis approach was used as the basis for regional land cover mapping, fire disturbance-regeneration, and multiresolution land cover scaling studies in the boreal forest ecosystem of central Canada. The land cover classification was developed by using regional field observations from ground and low-level aircraft transits to analyze spectral-temporal clusters that were derived from an unsupervised cluster analysis of monthly normalized difference vegetation index (NDVI) image composites (April-September 1992). Quantitative areal proportions of the major boreal forest components were determined for a 821 km × 619 km region, ranging from the southern grasslands-boreal forest ecotone to the northern boreal transitional forest. The boreal wetlands (mostly lowland black spruce, tamarack, mosses, fens, and bogs) occupied approximately 33% of the region, while lakes accounted for another 13%. Upland mixed coniferous-deciduous forests represented 23% of the ecosystem. A SW-NE productivity gradient across the region is manifested by three levels of tree stand density for both the boreal wetland conifer and the mixed forest classes, which are generally aligned with isopleths of regional growing degree days. Approximately 30% of the region was directly affected by fire disturbance within the preceding 30-35 years, especially in the Canadian Shield Zone where large fire-regeneration patterns contribute to the heterogeneous boreal landscape. Intercomparisons with land cover classifications derived from 30-m Landsat Thematic Mapper (TM) data provided important insights into the relative accuracy of the 1 km AVHRR land cover classification. Primarily due to the multitemporal NDVI image compositing process, the 1 km AVHRR land cover classes have an effective spatial resolution in the 3-4 km range; therefore fens, bogs, small water bodies, and small patches of dry jack pine cannot be resolved within

  9. Pre- and Post-Harvest Carbon Dioxide Fluxes from an Upland Boreal Aspen (Populus tremuloides) Forest in Western Boreal Plain, Alberta, Canada

    Science.gov (United States)

    Giroux, Kayla

    The Utikuma Region Study Area (URSA) is located in north-central Alberta, Canada, in a region where aspen (Populus tremuloides) dominate the upland vegetation of the Western Boreal Plain Due to the heterogeneity of the surficial geology as well as the sub-humid climate where the water balance is dominated by evapotranspiration, the carbon balance across this landscape is highly variable. Moreover, the upland aspen regions represent significant stores of carbon. More recently, aspen stands have become valuable commercial resources for pulp and paper processing. These stands are harvested through a clear cutting process and are generally left to regenerate on their own, a process which occurs rapidly in clonal species like aspen. Since clonal species establish very quickly following harvest, information on the key ecohydrological controls on stand carbon dioxide (CO2) exchange from the years immediately following harvest are essential to understand the successional trajectory. However, most information currently available on these interactions are obtained several years following a disturbance. Thus, to determine the effects of harvest on aspen regeneration and productivity, ecosystem level fluxes of CO2 three years before and three years after timber harvest were analyzed. Prior to harvest, the ecosystem sequestered 1216 to 1286 g CO2 m-2period-1 over the growing season. Immediately after harvest, the ecosystem became a significant source of CO2 ranging from -874 to -1183 g CO2 m -2period-1, while the second growing season ranged from -233 to -577 g CO2 m-2period-1. The third growing season resulted in a net sink (76 g CO2 m -2period-1) over the same period, but if extrapolated over the whole year, the ecosystem would remain a source of carbon. The magnitude of Gross Ecosystem Productivity (GEP) returned pre-harvest range within two growing seasons. Ecosystem respiration (RE), on the other hand, increased year over year after harvest had taken place. Forest floor

  10. Holocene variations of wildfire occurrence as a guide for sustainable management of the northeastern Canadian boreal forest

    Institute of Scientific and Technical Information of China (English)

    Ahmed; El-Guellab; Hugo; Asselin; Sylvie; Gauthier; Yves; Bergeron; Adam; A.Ali

    2015-01-01

    Background: Cumulative impacts of wildfires and forest harvesting can cause shifts from closed-crown forest to open woodland in boreal ecosystems. To lower the probability of occurrence of such catastrophic regime shifts,forest logging must decrease when fire frequency increases, so that the combined disturbance rate does not exceed the Holocene maximum. Knowing how climate warming will affect fire regimes is thus crucial to sustainably manage the forest. This study aimed to provide a guide to determine sustainable forest harvesting levels, by reconstructing the Holocene fire history at the northern limit of commercial forestry in Quebec using charcoal particles preserved in lake sediments.Methods: Sediment cores were sampled from four lakes located close to the northern limit of commercial forestry in Quebec. The cores were sliced into consecutive 0.5 cm thick subsamples from which 1 cm3 was extracted to count and measure charcoal particles larger than 150 microns. Age-depth models were obtained for each core based on accelerator mass spectroscopy(AMS) radiocarbon dates. Holocene fire histories were reconstructed by combining charcoal counts and age-depth models to obtain charcoal accumulation rates and, after statistical treatment,long-term trends in fire occurrence(expressed as number of fires per 1000 years).Results: Fire occurrence varied between the four studied sites, but fires generally occurred more often during warm and dry periods of the Holocene, especially during the Holocene Thermal Maximum(7000–3500 cal. BP), when fire occurrence was twice as high as at present.Conclusions: The current fire regime in the study area is still within the natural range of variability observed over the Holocene. However, climatic conditions comparable to the Holocene Thermal Maximum could be reached within the next few decades, thus substantially reducing the amount of wood available to the forest industry.

  11. Holocene variations of wildfire occurrence as a guide for sustainable management of the northeastern Canadian boreal forest

    Directory of Open Access Journals (Sweden)

    Ahmed El-Guellab

    2015-05-01

    Full Text Available Background Cumulative impacts of wildfires and forest harvesting can cause shifts from closed-crown forest to open woodland in boreal ecosystems. To lower the probability of occurrence of such catastrophic regime shifts, forest logging must decrease when fire frequency increases, so that the combined disturbance rate does not exceed the Holocene maximum. Knowing how climate warming will affect fire regimes is thus crucial to sustainably manage the forest. This study aimed to provide a guide to determine sustainable forest harvesting levels, by reconstructing the Holocene fire history at the northern limit of commercial forestry in Quebec using charcoal particles preserved in lake sediments. Methods Sediment cores were sampled from four lakes located close to the northern limit of commercial forestry in Quebec. The cores were sliced into consecutive 0.5 cm thick subsamples from which 1 cm3 was extracted to count and measure charcoal particles larger than 150 microns. Age-depth models were obtained for each core based on accelerator mass spectroscopy (AMS radiocarbon dates. Holocene fire histories were reconstructed by combining charcoal counts and age-depth models to obtain charcoal accumulation rates and, after statistical treatment, long-term trends in fire occurrence (expressed as number of fires per 1000 years. Results Fire occurrence varied between the four studied sites, but fires generally occurred more often during warm and dry periods of the Holocene, especially during the Holocene Thermal Maximum (7000–3500 cal. BP, when fire occurrence was twice as high as at present. Conclusions The current fire regime in the study area is still within the natural range of variability observed over the Holocene. However, climatic conditions comparable to the Holocene Thermal Maximum could be reached within the next few decades, thus substantially reducing the amount of wood available to the forest industry.

  12. 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

  13. Construction and Development of the Dagangshan Forest Ecosystem Research Station

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Established by the former Ministry of Forestry in 1986, Dagangshan Forest Ecosystem Research Station is one of the 14 national key sites in the field of ecosystem research. In this paper, the basic situation of Dagangshan Forest Ecosystem Station is described, including geographic location, natural conditions, biological resources, research conditions, instruments, achievement, prospects etc.

  14. First Polarimetric GNSS-R Measurements from a Stratospheric Flight over Boreal Forests

    Directory of Open Access Journals (Sweden)

    Hugo Carreno-Luengo

    2015-10-01

    Full Text Available The first-ever dual-frequency multi-constellation Global Navigation Satellite Systems Reflectometry (GNSS-R polarimetric measurements over boreal forests and lakes from the stratosphere are presented. Data were collected during the European Space Agency (ESA sponsored Balloon Experiments for University Students (BEXUS 19 stratospheric balloon experiment using the P(Y and C/A Reflect Ometer (PYCARO instrument operated in closed-loop mode. Maps of the polarimetric ratio for L1 and L2 Global Positioning System (GPS and GLObal Navigation Satellite System (GLONASS, and for E1 Galileo signals are derived from the float phase at 27,000 m height, and the specular points are geolocalized on the Earth’s surface. Polarimetric ratio ( maps over boreal forests are shown to be in the range 2–16 dB for the different GNSS codes. This result suggests that the scattering is taking place not only over the soil, but over the different forests elements as well. Additionally to the interpretation of the experimental results a theoretical investigation of the different contributions to the total reflectivity over boreal forests is performed using a bistatic scattering model. The simulated cross- (reflected Left Hand Circular Polarization LHCP and co-polar (reflected Right Hand Circular Polarization RHCP reflectivities are evaluated for the soil, the canopy, and the canopy–soil interactions for three different biomass densities: 725 trees/ha, 150 trees/ha and 72 trees/ha. For elevation angles larger than the Brewster angle, it is found that the cross-polar signal is dominant when just single reflections over the forests are evaluated, while in the case of multiple reflections the co-polar signal becomes the largest one. The first-ever dual-frequency multi-constellation Global Navigation Satellite Systems Reflectometry (GNSS-R polarimetric measurements over boreal forests and lakes from the stratosphere are presented. Data were collected during the European Space

  15. 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

  16. Managing Forests for Water in the Anthropocene—The Best Kept Secret Services of Forest Ecosystems

    OpenAIRE

    Creed, Irena F.; Marian Weber; Francesco Accatino; Kreutzweiser, David P.

    2016-01-01

    Water and forests are inextricably linked. Pressures on forests from population growth and climate change are increasing risks to forests and their aquatic ecosystem services (AES). There is a need to incorporate AES in forest management but there is considerable uncertainty about how to do so. Approaches that manage forest ecosystem services such as fiber, water and carbon sequestration independently ignore the inherent complexities of ecosystem services and their responses to management act...

  17. Archaeal communities in boreal forest tree rhizospheres respond to changing soil temperatures.

    Science.gov (United States)

    Bomberg, Malin; Münster, Uwe; Pumpanen, Jukka; Ilvesniemi, Hannu; Heinonsalo, Jussi

    2011-07-01

    Temperature has generally great effects on both the activity and composition of microbial communities in different soils. We tested the impact of soil temperature and three different boreal forest tree species on the archaeal populations in the bulk soil, rhizosphere, and mycorrhizosphere. Scots pine, silver birch, and Norway spruce seedlings were grown in forest humus microcosms at three different temperatures, 7-11.5°C (night-day temperature), 12-16°C, and 16-22°C, of which 12-16°C represents the typical mid-summer soil temperature in Finnish forests. RNA and DNA were extracted from indigenous ectomycorrhiza, non-mycorrhizal long roots, and boreal forest humus and tested for the presence of archaea by nested PCR of the archaeal 16S rRNA gene followed by denaturing gradient gel electrophoresis (DGGE) profiling and sequencing. Methanogenic Euryarchaeota belonging to Methanolobus sp. and Methanosaeta sp. were detected on the roots and mycorrhiza. The most commonly detected archaeal 16S rRNA gene sequences belonged to group I.1c Crenarchaeota, which are typically found in boreal and alpine forest soils. Interestingly, also one sequence belonging to group I.1b Crenarchaeota was detected from Scots pine mycorrhiza although sequences of this group are usually found in agricultural and forest soils in temperate areas. Tree- and temperature-related shifts in the archaeal population structure were observed. A clear decrease in crenarchaeotal DGGE band number was seen with increasing temperature, and correspondingly, the number of euryarchaeotal DGGE bands, mostly methanogens, increased. The greatest diversity of archaeal DGGE bands was detected in Scots pine roots and mycorrhizas. No archaea were detected from humus samples from microcosms without tree seedling, indicating that the archaea found in the mycorrhizosphere and root systems were dependent on the plant host. The detection of archaeal 16S rRNA gene sequences from both RNA and DNA extractions show that the

  18. 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

  19. Modelling atmospheric OH-reactivity in a boreal forest ecosystem

    DEFF Research Database (Denmark)

    Mogensen, D.; Smolander, S.; Sogachev, Andrey;

    2011-01-01

    measured OH sink, and in our opinion, the reason for missing OH-reactivity is due to unmeasured unknown BVOCs, and limitations in our knowledge of atmospheric chemistry including uncertainties in rate constants. Furthermore, we found that the OH-reactivity correlates with both organic and inorganic...

  20. Modelling atmospheric OH-reactivity in a boreal forest ecosystem

    DEFF Research Database (Denmark)

    Mogensen, D.; Smolander, S.; Sogachev, Andrey;

    2011-01-01

    the total measured OH sink, and in our opinion, the reason for missing OH-reactivity is due to unmeasured unknown BVOCs, and limitations in our knowledge of atmospheric chemistry including uncertainties in rate constants. Furthermore, we found that the OH-reactivity correlates with both organic and...

  1. Behaviour of radioactive cesium in northern boreal forest ecosystems

    International Nuclear Information System (INIS)

    Full text: In 1997-2001 a large number of environmental samples have been collected from the Muddusjaervi area in Finnish Lappland. These samples include soil, water, sediment, vegetation and fish samples. Radioactive contamination in this subarctic environment has mainly resulted from the nuclear weapons test fallout in the 1950s and 1960s. Chernobyl accident did not considerably increase the contamination level in this area. The Laboratory of Radiochemistry, University of Helsinki, has been studying the behaviour of fallout radionuclides in the environment and in food chains in Lappland from the beginning of the 1960s. The study area lies in the middle of northern reindeer herding area where accumulation of radioactive cesium has been observed in food chains. In this paper we report on the behaviour of radioactive cesium in soil columns. The soil in this area is typically nutrient-poor podzolic soil. Altogether thirty soil columns were collected and they were divided into horizons (litter, organic and mineral layers). The activity concentrations of the horizons were determined by gamma spectrometry. In general, cesium has been concentrated mainly in the litter and organic layers and it has not been migrated considerably to mineral layers. To study the long term behaviour of cesium in soil the activity concentrations have been compared to those found in earlier decades and to the activity concentrations earlier determined for other radionuclides, especially for Pu. A further major objective was to study runoff of radionuclides from ground to lakes and brooks and therefore many of the soil samples were collected from various distances from lakes and brooks. (author)

  2. 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

  3. The resilience and functional role of moss in boreal and arctic ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Turetsky, Merritt; Bond-Lamberty, Benjamin; Euskirchen, Eugenie S.; Talbot, Julie; Frolking, Steve; McGuire, A. David; Tuittila, Eeva-Stiina

    2012-08-24

    Mosses in boreal and arctic ecosystems are ubiquitous components of plant communities, represent an important component of plant diversity, and strongly influence the cycling of water, nutrients, energy and carbon. Here we use a literature review and synthesis as well as model simulations to explore the role of moss in ecological stability and resilience. Our literature review of moss community responses to disturbance showed all possible responses (increases, decreases, no change) within most disturbance categories in boreal and arctic regions. Our modeling simulations suggest that loss of moss within northern plant communities will reduce soil carbon accumulation primarily by influencing decomposition rates and soil nitrogen availability. While two models (HPM and STM-TEM) showed a significant effect of moss removal, results from the Biome-BGC and DVM-TEM models suggest that northern, moss-rich ecosystems would need to experience extreme perturbation before mosses were eliminated. We highlight a number of issues that have not been adequately explored in moss communities, such as functional redundancy and singularity, relationships between response and effect traits, phenotypical plasticity in traits, and whether the effects of moss on ecosystem processes scale with local abundance. We also suggest that as more models explore issues related to ecological resilience, issues related to both parameter and conceptual uncertainty should be addressed: are the models more limited by uncertainty in the parameterization of the processes included or by what is not represented in the model at all? It seems clear from our review that mosses need to be incorporated into models as one or more plant functional types, but more empirical work is needed to determine how to best aggregate species.

  4. Paying for Forest Ecosystem Services: Voluntary Versus Mandatory Payments

    Science.gov (United States)

    Roesch-McNally, Gabrielle E.; Rabotyagov, Sergey S.

    2016-03-01

    The emergence of new markets for forest ecosystem services can be a compelling opportunity for market diversification for private forest landowners, while increasing the provision of public goods from private lands. However, there is limited information available on the willingness-to-pay (WTP) for specific forest ecosystem services, particularly across different ecosystem market mechanisms. We utilize survey data from Oregon and Washington households to compare marginal WTP for forest ecosystem services and the total WTP for cost-effective bundles of forest ecosystem services obtained from a typical Pacific Northwest forest across two value elicitation formats representing two different ecosystem market mechanisms: an incentive-compatible choice experiment involving mandatory tax payments and a hypothetical private provision scenario modeled as eliciting contributions to the preferred forest management alternative via a provision point mechanism with a refund. A representative household's total WTP for the average forest management program was estimated at 217.59 per household/year under a mandatory tax mechanism and 160.44 per household/per year under a voluntary, crowdfunding-style, contribution mechanism; however, these estimates are not statistically different. Marginal WTP estimates were assessed for particular forest ecosystem service attributes including water quality, carbon storage, mature forest habitat, and public recreational access. This study finds that survey respondents place significant economic value on forest ecosystem services in both elicitation formats and that the distributions of the marginal WTP are not statistically significantly different.

  5. Urban forests and pollution mitigation: Analyzing ecosystem services and disservices

    International Nuclear Information System (INIS)

    The purpose of this paper is to integrate the concepts of ecosystem services and disservices when assessing the efficacy of using urban forests for mitigating pollution. A brief review of the literature identifies some pollution mitigation ecosystem services provided by urban forests. Existing ecosystem services definitions and typologies from the economics and ecological literature are adapted and applied to urban forest management and the concepts of ecosystem disservices from natural and semi-natural systems are discussed. Examples of the urban forest ecosystem services of air quality and carbon dioxide sequestration are used to illustrate issues associated with assessing their efficacy in mitigating urban pollution. Development of urban forest management alternatives that mitigate pollution should consider scale, contexts, heterogeneity, management intensities and other social and economic co-benefits, tradeoffs, and costs affecting stakeholders and urban sustainability goals. - Environmental managers should analyze ecosystem services and disservices when developing urban forest management alternatives for mitigating urban pollution.

  6. Alaska’s changing fire regime - Implications for the vulnerability of its boreal forests

    Science.gov (United States)

    Kasischke, Eric S.; Verbyla, David L.; Rupp, T. Scott; McGuire, Anthony; Murphy, Karen A.; Jandt, R.; Barnes, Jennifer L.; Hoy, E.; Duffy, Paul A; Calef, Monika; Turetsky, Merritt R.

    2010-01-01

    A synthesis was carried out to examine Alaska’s boreal forest fire regime. During the 2000s, an average of 767 000 ha·year–1 burned, 50% higher than in any previous decade since the 1940s. Over the past 60 years, there was a decrease in the number of lightning-ignited fires, an increase in extreme lightning-ignited fire events, an increase in human-ignited fires, and a decrease in the number of extreme human-ignited fire events. The fraction of area burned from human-ignited fires fell from 26% for the 1950s and 1960s to 5% for the 1990s and 2000s, a result from the change in fire policy that gave the highest suppression priorities to fire events that occurred near human settlements. The amount of area burned during late-season fires increased over the past two decades. Deeper burning of surface organic layers in black spruce (Picea mariana (Mill.) BSP) forests occurred during late-growing-season fires and on more well-drained sites. These trends all point to black spruce forests becoming increasingly vulnerable to the combined changes of key characteristics of Alaska’s fire regime, except on poorly drained sites, which are resistant to deep burning. The implications of these fire regime changes to the vulnerability and resilience of Alaska’s boreal forests and land and fire management are discussed.

  7. Alaska's Changing Fire Regime - Implications for the Vulnerability of Its Boreal Forests

    Science.gov (United States)

    Kasischke, E. S.; Hoy, E. E.; Verbyla, D. L.; Rupp, T. S.; Duffy, P. A.; McGuire, A. D.; Murphy, K. A.; Jandt, R.; Barnes, J. L.; Calef, M.; Turetsky, M. R.

    2010-01-01

    A synthesis was carried out to examine Alaska s boreal forest fire regime. During the 2000s, an average of 767 000 ha/year burned, 50% higher than in any previous decade since the 1940s. Over the past 60 years, there was a decrease in the number of lightning-ignited fires, an increase in extreme lightning-ignited fire events, an increase in human-ignited fires, and a decrease in the number of extreme human-ignited fire events. The fraction of area burned from humanignited fires fell from 26% for the 1950s and 1960s to 5% for the 1990s and 2000s, a result from the change in fire policy that gave the highest suppression priorities to fire events that occurred near human settlements. The amount of area burned during late-season fires increased over the past two decades. Deeper burning of surface organic layers in black spruce (Picea mariana (Mill.) BSP) forests occurred during late-growing-season fires and on more well-drained sites. These trends all point to black spruce forests becoming increasingly vulnerable to the combined changes of key characteristics of Alaska s fire regime, except on poorly drained sites, which are resistant to deep burning. The implications of these fire regime changes to the vulnerability and resilience of Alaska s boreal forests and land and fire management are discussed.

  8. Snowpack concentrations and estimated fluxes of volatile organic compounds in a boreal forest

    Directory of Open Access Journals (Sweden)

    H. Aaltonen

    2012-06-01

    Full Text Available Soil provides an important source of volatile organic compounds (VOCs to atmosphere, but in boreal forests these fluxes and their seasonal variations have not been characterized in detail. Especially wintertime fluxes are almost completely unstudied. In this study, we measured the VOC concentrations inside the snowpack in a boreal Scots pine (Pinus sylvestris L. forest in southern Finland, using adsorbent tubes and air samplers installed permanently in the snow profile. Based on the VOC concentrations at three heights inside the snowpack, we estimated the fluxes of these gases. We measured 20 VOCs from the snowpack, monoterpenes being the most abundant group with concentrations varying from 0.11 to 16 μg m−3. Sesquiterpenes and oxygen-containing monoterpenes were also detected. Inside the pristine snowpack, the concentrations of terpenoids decreased from soil surface towards the surface of the snow, suggesting soil as the source for terpenoids. Forest damages (i.e. broken treetops and branches, fallen trees resulting from heavy snow loading during the measurement period increased the terpenoid concentrations dramatically, especially in the upper part of the snowpack. The results show that soil processes are active and efficient VOC sources also during winter, and that natural or human disturbance can increase forest floor VOC concentrations substantially. Our results stress the importance of soil as a source of VOCs during the season when other biological sources, such as plants, have lower activity.

  9. Snowpack concentrations and estimated fluxes of volatile organic compounds in a boreal forest

    Directory of Open Access Journals (Sweden)

    H. Aaltonen

    2012-01-01

    Full Text Available Soil forms an important source for volatile organic compounds (VOCs, but in boreal forests these fluxes and their seasonal variations have not been characterized in detail, especially wintertime fluxes, which are almost completely unstudied. In this study, we measured the VOC concentrations inside a snowpack in a boreal Scots pine (Pinus sylvestris L. forest in southern Finland, using adsorbent tubes and air samplers installed permanently in the snow profile. Based on the VOC concentrations at three heights inside the snowpack, we estimated the fluxes of these gases. We measured 20 VOCs from the snowpack, monoterpenes being the most abundant group with concentrations varying from 0.11 to 16 μg m−3. Sesquiterpenes and oxygen-containing monoterpenes were also detected. Inside the pristine snowpack, the concentrations of terpenoids decreased from the soil surface towards the snow surface, suggesting soil as being the source for terpenoids. Forest damages resulting from heavy snow loading during the measurement period increased the terpenoid concentrations dramatically, especially in the upper part of the snowpack. The results show that soil processes are also active and efficient VOC sources during winter and that natural or human disturbance can increase forest floor VOC concentrations substantially. Our results stress the importance of soil as a source of VOCs during the season when other biological sources, basically plants, have lower activity.

  10. Snowpack concentrations and estimated fluxes of volatile organic compounds in a boreal forest

    Science.gov (United States)

    Aaltonen, H.; Pumpanen, J.; Hakola, H.; Vesala, T.; Rasmus, S.; Bäck, J.

    2012-06-01

    Soil provides an important source of volatile organic compounds (VOCs) to atmosphere, but in boreal forests these fluxes and their seasonal variations have not been characterized in detail. Especially wintertime fluxes are almost completely unstudied. In this study, we measured the VOC concentrations inside the snowpack in a boreal Scots pine (Pinus sylvestris L.) forest in southern Finland, using adsorbent tubes and air samplers installed permanently in the snow profile. Based on the VOC concentrations at three heights inside the snowpack, we estimated the fluxes of these gases. We measured 20 VOCs from the snowpack, monoterpenes being the most abundant group with concentrations varying from 0.11 to 16 μg m-3. Sesquiterpenes and oxygen-containing monoterpenes were also detected. Inside the pristine snowpack, the concentrations of terpenoids decreased from soil surface towards the surface of the snow, suggesting soil as the source for terpenoids. Forest damages (i.e. broken treetops and branches, fallen trees) resulting from heavy snow loading during the measurement period increased the terpenoid concentrations dramatically, especially in the upper part of the snowpack. The results show that soil processes are active and efficient VOC sources also during winter, and that natural or human disturbance can increase forest floor VOC concentrations substantially. Our results stress the importance of soil as a source of VOCs during the season when other biological sources, such as plants, have lower activity.

  11. Cycling of radiocesium in forest ecosystems

    International Nuclear Information System (INIS)

    A review is given of results on 137Cs and potassium behavior in forest ecosystems following an atmospheric contamination after an accidental release. Data are given on the correlation coefficients 137Cs versus K in the Belgian Ardennes forest in the period December 1988 to March 1990. Experiments were performed in Norwegian spruce and oak stands. Data are also given on 137Cs distribution in soil layers of Bourakovka and Novo-Shepelichi polygons in the Chernobyl-contaminated area, and on radiocesium contamination of the red pine stand in Bourakovka. A correlation was found in the behavior of both elements in plants. Observations and studies of their behavior in multilayer soils, however, showed some discrepancies. (J.B.) 4 tabs., 2 figs., 20 refs

  12. Radiocesium in a Danish pine forest ecosystem

    DEFF Research Database (Denmark)

    Strandberg, M.

    1994-01-01

    During the autumn of 1991, a Scots pine forest, Tisvilde Hegn, was investigated with respect to the distribution of radiocesium on compartments in the forest ecosystem. The sandy acidic soil is poor, with a approximately 5-cm thick layer of organic soil, and clay content is very low, between 0 and...... included. The concentrations of radiocesium are highest in the endshoots of the pine trees, and lowest in the hardwood. There are indications that the Chernobyl cesium is mainly distributed in the parts of the tres that have been formed since 1986. Observed Ratios (OR) were used to characterize the ability...... 2%. Cesium from Chernobyl is still totally in the upper 5 cm, while almost half of the fallout cesium has penetrated to depths lower than 5 cm. More than 95% of the total amount of Cs-137 is in the soil compartment. The rest is mainly in the trees (3.4%) and vegetation (0.4%), moss and lichen...

  13. Patterns in potassium dynamics in forest ecosystems.

    Science.gov (United States)

    Tripler, Christopher E; Kaushal, Sujay S; Likens, Gene E; Walter, M Todd

    2006-04-01

    significance warrant further study. We suggest that knowledge about the dynamics of this understudied element is imperative for our understanding patterns and processes in forest ecosystems. PMID:16623731

  14. Public Opinions and Use of Various Types of Recreational Infrastructure in Boreal Forest Settings

    Directory of Open Access Journals (Sweden)

    Vegard Gundersen

    2016-05-01

    Full Text Available We have investigated public preferences for use intensity and visual quality of forest recreational infrastructure. Forest infrastructure covers five classes, along a continuum from unmarked paths to paved walkways. Altogether, 39 sites were categorized into the five classes and measured with automatic counters. A sample of 545 respondents living in southeastern and middle Norway were asked to rate 15 forest scenes and 35 preconceptions of recreational settings. The path scenarios were depicted as digitally calibrated photos that systematically displayed physical path feature in boreal, semi-natural settings. Survey participants showed a clearly greater preference for photos and preconceptions of forests settings containing minor elements of forest infrastructure; unmarked paths received the highest score and forest roads/walkways/bikeways the lowest. We identified a clear mismatch between public preferences for forest infrastructure and the intensity of use; the less appreciated infrastructure was the most used. Planning and management has to consider these different needs for recreational infrastructure, and we propose an area zoning system that meets the different segments of forest visitors.

  15. Size-based hydroacoustic measures of within-season fish abundance in a boreal freshwater ecosystem.

    Directory of Open Access Journals (Sweden)

    Riley A Pollom

    Full Text Available Eleven sequential size-based hydroacoustic surveys conducted with a 200 kHz split-beam transducer during the summers of 2011 and 2012 were used to quantify seasonal declines in fish abundance in a boreal reservoir in Manitoba, Canada. Fish densities were sufficiently low to enable single target resolution and tracking. Target strengths converted to log2-based size-classes indicated that smaller fish were consistently more abundant than larger fish by a factor of approximately 3 for each halving of length. For all size classes, in both years, abundance (natural log declined linearly over the summer at rates that varied from -0.067 x day(-1 for the smallest fish to -0.016 x day(-1 for the largest (R2 = 0.24-0.97. Inter-annual comparisons of size-based abundance suggested that for larger fish (>16 cm, mean winter decline rates were an order of magnitude lower (-0.001 x day(-1 and overall survival higher (71% than in the main summer fishing season (mean loss rate -0.038 x day(-1; survival 33%. We conclude that size-based acoustic survey methods have the potential to assess within-season fish abundance dynamics, and may prove useful in long-term monitoring of productivity and hence management of boreal aquatic ecosystems.

  16. 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...

  17. Quantifying the missing link between albedo and productivity of boreal forests

    Science.gov (United States)

    Hovi, Aarne; Liang, Jingjing; Korhonen, Lauri; Kobayashi, Hideki; Rautiainen, Miina

    2016-04-01

    Albedo and fraction of absorbed photosynthetically active radiation (FAPAR) determine the shortwave radiation balance and productivity of forests. Several studies have examined the relation between forest structure and albedo in the boreal zone. Studies regarding FAPAR are fewer and the relations between albedo and FAPAR are still poorly understood. To study these relations we simulated shortwave black sky albedo and canopy FAPAR, using the FRT forest reflectance model. We used two sets of field plots as input data. The plots were located in Alaska, USA (N = 584) and in Finland (N = 506) between Northern latitudes of 60° and 68° , and they represent naturally grown and more intensively managed (regularly thinned) forests, respectively. The simulations were carried out with sun zenith angles (SZA) typical to the biome, ranging from 40° to 80° . The simulated albedos in coniferous plots decreased with increasing tree height, whereas canopy FAPAR showed an opposite trend. The albedo of broadleaved plots was notably higher than that of coniferous plots. No species differences in canopy FAPAR were seen, except for pine forests in Finland that showed lowest FAPAR among species. Albedo and canopy FAPAR were negatively correlated (r ranged from -0.93 to -0.69) in coniferous plots. The correlations were notably weaker (r ranged from -0.64 to 0.05) if plots with broadleaved trees were included. To show the influence of forest management, we further examined the response of albedo and FAPAR to forest density (basal area) and fraction of broadleaved trees. Plots with low basal area showed high albedos but also low canopy FAPAR. When comparing the sparse plots to dense ones, the relative decrease in canopy FAPAR was larger than the relative increase in albedo. However, at large SZAs the basal area could be lowered to approx. 20 m2 ha‑1 before FAPAR was notably reduced. Increasing the proportion of broadleaved trees from 0% to 100% increased the albedos to approximately

  18. 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

    Full Text Available The carbon (C cycle in boreal regions is strongly influenced by fire, which converts biomass and detrital C mainly to gaseous forms (CO2 and smaller proportions of CO and CH4, and some 1–7% of mass to pyrogenic C (PyC. PyC is mainly produced as solid charred residues, including visually-defined charcoal, and a black carbon (BC fraction chemically defined by its resistance to laboratory oxidation, plus much lower proportions of volatile soot and polycyclic aromatic hydrocarbons (PAHs. All PyC is characterized by fused aromatic rings, but varying in cluster sizes, and presence of other elements (N, O and functional groups. There are several reasons for current interest in defining more precisely the role of PyC in the C cycle of boreal regions. First, PyC is resistant to decomposition, and therefore contributes to very stable C pools in soils and sediments. Second, it influences soil processes, mainly through its sorption properties and cation exchange capacity, and third, soot aerosols absorb solar radiation and may contribute to global warming. However, there are large gaps in the basic information needed to address these topics. While charcoal is commonly defined by visual criteria, analytical methods for BC are mainly based on various measures of oxidation resistance, or on yield of benzenepolycarboxylic acids. These methods are still being developed, and capture different fractions of the PyC "continuum". There are few quantitative reports of PyC production and stocks in boreal forests (essentially none for boreal peatlands, and results are difficult to compare due to varying experimental goals and methods, as well as inconsistent terminology. There are almost no direct field measurements of BC aerosol production from boreal 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

  19. Estimation of Boreal Forest Biomass Using Spaceborne SAR Systems

    Science.gov (United States)

    Saatchi, Sassan; Moghaddam, Mahta

    1995-01-01

    In this paper, we report on the use of a semiempirical algorithm derived from a two layer radar backscatter model for forest canopies. The model stratifies the forest canopy into crown and stem layers, separates the structural and biometric attributes of the canopy. The structural parameters are estimated by training the model with polarimetric SAR (synthetic aperture radar) data acquired over homogeneous stands with known above ground biomass. Given the structural parameters, the semi-empirical algorithm has four remaining parameters, crown biomass, stem biomass, surface soil moisture, and surface rms height that can be estimated by at least four independent SAR measurements. The algorithm has been used to generate biomass maps over the entire images acquired by JPL AIRSAR and SIR-C SAR systems. The semi-empirical algorithms are then modified to be used by single frequency radar systems such as ERS-1, JERS-1, and Radarsat. The accuracy. of biomass estimation from single channel radars is compared with the case when the channels are used together in synergism or in a polarimetric system.

  20. Forest ecosystem health assessment and analysis in China

    Institute of Scientific and Technical Information of China (English)

    XIAOFengjin; OUYANGHua; ZHANGQiang; FUBojie; ZHANGZhicheng

    2004-01-01

    Based on more than 300 forest sample plots surveying data and forestry statistical data, remote sensing information from the NOAA AVHRR database and the daily meteorological data of 300 stations, we selected vigor, organization and resilience as the indicators to assess large-scale forest ecosystem health in China and analyzed the spatial pattern of forest ecosystem health and influencing factors. The results of assessment indicated that the spatial pattern of forest ecosystem health showed a decreasing trend along latitude gradients and longitude gradients. The healthy forests are mainly distributed in natural forests, tropical rainforests and seasonal rainforests; secondarily orderly in northeast national forest zone, subtropical forest zonation and southwest forest zonation; while the unhealthy forests were mainly located in warm temperate zone and Xinjiang-Mongolia forest zone. The coefficient of correction between Forest Ecosystem Health Index (FEHI) and annual average precipitation was 0.58 (p<0.01), while the coefficient of correlation between FEHI and annual mean temperatures was 0.49 (p<0.01), which identified that the precipitation and temperatures affect the pattern of FEHI, and the precipitation's effect was stronger than the temperature's. We also measured the correlation coefficient between FEHI and NPP, biodiversity and resistance, which were 0.64, 0.76 and 0.81 (p<0.01) respectively. The order of effect on forest ecosystem health was vigor, organization and resistance.

  1. Soil-to-plant transfer of uranium and its distribution between plant parts in four boreal forest species

    International Nuclear Information System (INIS)

    Uranium (U) can be released to the environment through the entire nuclear fuel cycle. U uptake by plants is an important process for possible adverse effects in ecosystems. The soil-to-plant transfer of natural U and its distribution across plant parts were investigated in May lily (Maianthemum bifolium), narrow buckler fern (Dryopteris carthusiana), rowan (Sorbus aucuparia) and Norway spruce (Picea abies). Concentration ratios (CR) between plant and soil were calculated. The CRs for roots were higher than those for the above-ground parts of the plants. Soil pH was the only soil parameter showing an effect on CRs. No significant differences were noticed between species. The CRs observed were consistent with those reported previously in other forest types. The pooled values of 0.06 for roots and 0.005 for stems/petioles and leaves/needles can be considered as good estimates of CR values to be used in modelling the U uptake in boreal forest species. (orig.)

  2. Effects of Tree Canopy Structure and Understory Vegetation on the Effectiveness of Open-Top-Chamber in Manipulating Boreal Forest Microclimate

    Science.gov (United States)

    Teuber, L. M.; Nilsson, M. C.; Wardle, D.; Dorrepaal, E.

    2014-12-01

    Open-top chambers (OTCs) are widely used to passively increase soil and air temperature in various open habitats, such as alpine and arctic tundra, and temperate grasslands. Several studies report warming effects of 1-2 °C in arctic and alpine tundra, and up to 6 °C in temperate grasslands. The variation between studies can be mostly attributed to differences in the abiotic environment, such as snow cover and solar irradiance. Vegetation height and openness affects the amount of irradiance that reaches the ground and may therefore indirectly impact the effectiveness of OTCs. The use of OTCs in forested ecosystems might therefore be limited by reduced canopy openness, while their effect on changes in soil temperature and soil moisture content might additionally be affected by the understory vegetation type and cover. Nevertheless, OTC's are an immensely useful tool in climate-change studies, and could benefit research in forest ecosystems. In this study we therefore investigated whether OTCs can be used to manipulate microclimate in the northern boreal forest and how tree canopy cover and understory vegetation influence OTC effects on air and soil temperature and on soil moisture content.We compared OTC effects at ten sites that were situated along a fire chronosequence in the northern boreal forest in Sweden. Sites were dominated by Pinus sylvestris and Picea abies, and time since the last fire ranged from 47-367 years, resulting in varying degrees of tree canopy openness. We applied full factorial combinations of OTC warming and dwarf shrub removal and moss removal at each site. We measured canopy cover using hemispherical photography; air and soil temperature as well as soil moisture were measured hourly from June until September. Preliminary analyses indicate that OTCs increased monthly mean air temperatures by up to 0.9 °C across all treatments and forest stands. However, the degree of warming showed clear relations with the presence or absence of the

  3. Northern Forest Ecosystem Dynamics Using Coupled Models and Remote Sensing

    Science.gov (United States)

    Ranson, K. J.; Sun, G.; Knox, R. G.; Levine, E. R.; Weishampel, J. F.; Fifer, S. T.

    1999-01-01

    Forest ecosystem dynamics modeling, remote sensing data analysis, and a geographical information system (GIS) were used together to determine the possible growth and development of a northern forest in Maine, USA. Field measurements and airborne synthetic aperture radar (SAR) data were used to produce maps of forest cover type and above ground biomass. These forest attribute maps, along with a conventional soils map, were used to identify the initial conditions for forest ecosystem model simulations. Using this information along with ecosystem model results enabled the development of predictive maps of forest development. The results obtained were consistent with observed forest conditions and expected successional trajectories. The study demonstrated that ecosystem models might be used in a spatial context when parameterized and used with georeferenced data sets.

  4. 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

  5. Monitoring the broadleaf fraction and canopy cover of boreal forests using spectral invariants

    Science.gov (United States)

    Vanhatalo, Kalle M.; Rautiainen, Miina; Stenberg, Pauline

    2014-01-01

    A recent method based on the spectral invariants theory to retrieve physically-based information on forest properties from remotely sensed hyperspectral imagery was tested in a southern boreal setting in central Finland. An atmospherically corrected Hyperion image and ground measurements from 66 forest stands were used. First, the novel concept of transformed green leaf single scattering spectral albedos was tested against leaf (needle) albedo measurements on Scots pine, Norway spruce and Silver birch from the study area. We found the transformed Beaked hazel albedo applied in previous studies could be used as reference also for the boreal tree species. Second, we derived a newly suggested spectrally invariant variable, the directional area scattering factor (DASF), to estimate the broadleaf fraction of forest stands. Based on our results, DASF seems highly promising as a potential new hyperspectral satellite product for change monitoring of broadleaf fraction over different vegetation zones. Finally, we plotted our results in the spectral invariants space, and suggest a new interpretation for the reference-dependent structural parameter pR. We propose this parameter is an indicator of canopy cover and suffers less from saturation problems than vegetation indices.

  6. Postfire Succession of Ants (Hymenoptera: Formicidae) Nesting in Dead Wood of Northern Boreal Forest.

    Science.gov (United States)

    Boucher, Philippe; Hébert, Christian; Francoeur, André; Sirois, Luc

    2015-10-01

    Dead wood decomposition begins immediately after tree death and involves a large array of invertebrates. Ecological successions are still poorly known for saproxylic organisms, particularly in boreal forests. We investigated the use of dead wood as nesting sites for ants along a 60-yr postfire chronosequence in northeastern coniferous forests. We sampled a total of 1,625 pieces of dead wood, in which 263 ant nests were found. Overall, ant abundance increased during the first 30 yr after wildfire, and then declined. Leptothorax cf. canadensis Provancher, the most abundant species in our study, was absent during the first 2 yr postfire, but increased steadily until 30 yr after fire, whereas Myrmica alaskensis Wheeler, second in abundance, was found at all stages of succession in the chronosequence. Six other species were less frequently found, among which Camponotus herculeanus (Linné), Formica neorufibarbis Emery, and Formica aserva Forel were locally abundant, but more scarcely distributed. Dead wood lying on the ground and showing numerous woodborer holes had a higher probability of being colonized by ants. The C:N ratio was lower for dead wood colonized by ants than for noncolonized dead wood, showing that the continuous occupation of dead wood by ants influences the carbon and nitrogen dynamics of dead wood after wildfire in northern boreal forests. PMID:26314011

  7. [Evaluation of economic forest ecosystem services in China].

    Science.gov (United States)

    Wang, Bing; Lu, Shao-Wei

    2009-02-01

    This paper quantitatively evaluated the economic forest ecosystem services in the provinces of China in 2003, based on the long-term and continuous observations of economic forest ecosystems in this country, the sixth China national forest resources inventory data, and the price parameter data from the authorities in the world, and by applying the law of market value, the method of substitution of the expenses, and the law of the shadow project. The results showed that in 2003, the total value of economic forest ecosystem services in China was 11763.39 x 10(8) yuan, and the total value of the products from economic forests occupied 19.3% of the total ecosystem services value, which indicated that the economic forests not only provided society direct products, but also exhibited enormous eco-economic value. The service value of the functions of economic forests was in the order of water storage > C fixation and O2 release > biodiversity conservation > erosion control > air quality purification > nutrient cycle. The spatial pattern of economic forest ecosystem services in the provinces of China had the same trend with the spatial distribution of water and heat resources and biodiversity. To understand the differences of economic forest ecosystem services in the provinces of China was of significance in alternating the irrational arrangement of our present forestry production, diminishing the abuses of forest management, and establishing high grade, high efficient, and modernized economic forests. PMID:19459385

  8. Comparing Effects of Climate Warming, Fire, and Timber Harvesting on a Boreal Forest Landscape in Northeastern China

    OpenAIRE

    Li, Xiaona; He, Hong S.; Wu, Zhiwei; Liang, Yu; Schneiderman, Jeffrey E.

    2013-01-01

    Forest management under a changing climate requires assessing the effects of climate warming and disturbance on the composition, age structure, and spatial patterns of tree species. We investigated these effects on a boreal forest in northeastern China using a factorial experimental design and simulation modeling. We used a spatially explicit forest landscape model (LANDIS) to evaluate the effects of three independent variables: climate (current and expected future), fire regime (current and ...

  9. Stomata-controlled nighttime COS fluxes in a boreal forest: implications for the use of COS as a GPP tracer

    Science.gov (United States)

    Kooijmans, Linda M. J.; Maseyk, Kadmiel; Seibt, Ulli; Vesala, Timo; Mammarella, Ivan; Baker, Ian T.; Franchin, Alessandro; Kolari, Pasi; Sun, Wu; Keskinen, Helmi; Levula, Janne; Chen, Huilin

    2016-04-01

    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. This close coupling is the fundamental principle for the use of COS as tracer for GPP. Nonetheless, in contrast to CO2 , the uptake of COS by vegetation is not light-dependent, and therefore the vegetative uptake of COS can continue during the night as long as stomata are open. Nighttime stomatal conductance is observed in a variety of studies, and also nighttime depletion of COS concentrations is reported several times but it is not confirmed with field measurements that the depletion of COS in the night is indeed driven by stomatal opening. In the summer of 2015 a campaign took place at the SMEAR II site in Hyytiälä, Finland to provide better constrained COS flux data for boreal forests using a combination of COS measurements, i.e. atmospheric profile concentrations up to 125 m, eddy-covariance fluxes and soil chamber fluxes, and collocated measurements of stomatal conductance and 222Radon. A high correlation between concentrations of 222Radon and COS implies that the radon-tracer method is a valuable tool to derive nighttime ecosystem COS fluxes. We find that soils contribute to 17% of the total ecosystem COS flux during nighttime in the peak growing season. Nighttime ecosystem COS fluxes show a correlation with stomatal conductance (R2 = 0.3), indicating that nighttime COS fluxes are primarily driven by vegetation. The COS vegetation fluxes will be compared with calculated fluxes from the Simple Biosphere model. Furthermore, the nighttime vegetative COS uptake covers a substantial fraction (25%) of the daily maximum COS uptake by vegetation. Accurate quantification of nighttime COS uptake is required to be able to use COS as a useful tracer for GPP.

  10. Mapping permafrost in the boreal forest with Thematic Mapper satellite data

    Science.gov (United States)

    Morrissey, L. A.; Strong, L. L.; Card, D. H.

    1986-01-01

    A geographic data base incorporating Landsat TM data was used to develop and evaluate logistic discriminant functions for predicting the distribution of permafrost in a boreal forest watershed. The data base included both satellite-derived information and ancillary map data. Five permafrost classifications were developed from a stratified random sample of the data base and evaluated by comparison with a photo-interpreted permafrost map using contingency table analysis and soil temperatures recorded at sites within the watershed. A classification using a TM thermal band and a TM-derived vegetation map as independent variables yielded the highest mapping accuracy for all permafrost categories.

  11. Seasonal and inter-annual variability of energy exchange above a boreal Scots pine forest

    OpenAIRE

    S. Launiainen

    2010-01-01

    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...

  12. Seasonal and inter annual variability of energy exchange above a boreal Scots pine forest

    OpenAIRE

    S. Launiainen

    2010-01-01

    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

  13. Changing sources of soil respiration with time since fire in a boreal forest

    OpenAIRE

    Czimczik, CI; Trumbore, SE; Carbone, MS; Winston, GC

    2006-01-01

    Radiocarbon signatures (Δ14C) of carbon dioxide (CO2) provide a measure of the age of C being decomposed by microbes or respired by living plants. Over a 2-year period, we measured Δ14C of soil respiration and soil CO2 in boreal forest sites in Canada, which varied primarily in the amount of time since the last stand-replacing fire. Comparing bulk respiration Δ14C with Δ14C of CO2 evolved in incubations of heterotrophic (decomposing organic horizons) and autotrophic (root and moss) components...

  14. Fire history and ecology of the boreal forest nature reserve Trillemarka-Rollagsfjell

    OpenAIRE

    Nkrumah-Boakye, Joseph

    2014-01-01

    ABSTRACT Macroscopic charcoal particles (axis ≥ 0.5mm) give an indication of local fire presence to a fine spatial accuracy. I have examined the history, distribution and impact of fires on the ecology of Trillemarka-Rollagsfjell boreal forest nature reserve, located in the south of Norway. Data were obtained from a total of 225 soil core samples from 15 macro sample plots measuring 300 x 300m2. There was macroscopic charcoal in 153 of the soil samples out of 225, giving an estimated b...

  15. 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....

  16. Influence of Time since Fire and Micro-Habitat Availability on Terricolous Lichen Communities in Black Spruce (Picea mariana Boreal Forests

    Directory of Open Access Journals (Sweden)

    Saliha Zouaoui

    2014-11-01

    Full Text Available Terricolous lichens are an important component of boreal forest ecosystems, both in terms of function and diversity. In this study, we examined the relative contribution of microhabitat characteristics and time elapsed since the last fire in shaping terricolous lichen assemblages in boreal forests that are frequently affected by severe stand-replacing fires. We sampled 12 stands distributed across five age classes (from 43 to >200 years. In each stand, species cover (% of all terricolous lichen species and species richness were evaluated within 30 microplots of 1 m2. Our results show that time elapsed since the last fire was the factor that contributed the most to explaining terricolous lichen abundance and species composition, and that lichen cover showed a quadratic relationship with stand age. Habitat variables such as soil characteristics were also important in explaining lichen richness. These results suggest that the presence of suitable substrates is not sufficient for the conservation of late-successional terricolous lichen communities in this ecosystem, and that they also need relatively long periods of times for species dispersal and establishment.

  17. Disturbances (fire and grazing by reindeer) and soil methane fluxes -- case studies from the subarctic boreal forest of Finish Lapland.

    Science.gov (United States)

    Köster, Kajar; Köster, Egle; Berninger, Frank; Pumpanen, Jukka

    2016-04-01

    In aerobic, well-drained environments such as boreal upland forest soils, methane (CH4) is oxidized by microbes, resulting into the soils acting as a sink of atmospheric CH4. The emission of CH4 is controlled primarily by soil moisture and temperature, but also by the availability of organic carbon. Forest fires are one of the predominant natural disturbances in subarctic boreal forests that strongly influence soil moisture and soil temperature values and carbon dynamics of the soils. At the same time also the effect of reindeer (Rangifer tarandus L.) grazing on soil moisture and temperature regimes in the lichen-dominated Arctic ecosystems has been found to be considerable. By removing the lichen carpet and damaging the secondary vegetation mat, reindeer make patches of bare soil common, and these factors in combination with trampling allow for soil to warm up faster, reach higher temperatures, and reduce the soil moisture content. We studied the effect of reindeer grazing and forest fire on fluxes of CH4 in northern boreal subarctic Scots pine forest stands. The study areas are in eastern Lapland, Värriö Strict Nature Reserve, Finland (67° 46' N, 29° 35' E). The sites are situated north of the Arctic Circle, near to the northern timberline at an average of 300 m altitude. For studing the effect of fire we have established sample areas (with three replicate plots in each) in a chronosequence of 4 age classes (2 to 152 years since the last fire). The fire chronosequence consisted of four types of areas with different time since the last forest fire: i) 5 years, ii) 45 years, iii) 70 years and iv) 155 years after fire. For studing the effect of reindeer grazing (comparison of grazed and non-grazed areas) we have established the study areas (10 sample plots in total established in year 2013) along the borderline between Finland and Russia. The ungrazed area was excluded from the reindeer grazing already in 1918, to prevent the Finnish reindeer from going to the

  18. Estimates of boreal forest vegetation rate based on electromagnetic radiation

    International Nuclear Information System (INIS)

    Complete text of publication follows. Applications of electromagnetic methods have greatly enhanced ability to monitor and manage in the areas of forestry. Accurate measurements of regional and global scale vegetation dynamics (phenology) are required to improve models and understanding of inter-annual variability in terrestrial ecosystem carbon exchange and climate-biosphere interactions. Study of vegetation phenology is required for understanding of variability in ecosystem. Remote sensing of the Earth traditionally has used reflected energy in the visible and infrared and emitted energy in the thermal infrared and microwave regions to gather radiation that can be analyzed numerically or used to generate images whose tonal variations represent different intensities of photons associated with a range of wavelengths that are received at the sensor. This sampling of a (continuous or discontinuous) range(s) of wavelengths is the essence of what is usually termed multispectral remote sensing. In this paper, monitoring of vegetation dynamics using remote sensing of the Earth is presented. Vegetation variability (vegetation rate) in different climatic areas is investigated. Original software using IDL interactive language for processing of satellite long-term data series was developed. To investigate growth dynamics vegetation rate inferred from remote sensing was used. All estimations based on annual time series of Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. Vegetation rate for Enhanced Vegetation Index (EVI) and Normalized Difference Vegetation Index (NDVI) was calculated using MODIS data. Time series covers 9 years, from 2000 to 2008. Comparison of EVI and NDVI derived growth rates has shown that NDVI derived rates reveal spatial structure better. Using long-term data of vegetation rates variance was estimated that helps to reveal areas with anomalous growth rate. Such estimation shows sensitivity degree of different areas to climatic changes. It

  19. Scale and Sensitivity of Songbird Occurrence to Landscape Structure in a Harvested Boreal Forest

    Directory of Open Access Journals (Sweden)

    Philip D. Taylor

    2005-12-01

    Full Text Available To explore the spatial scales at which boreal forest birds respond to landscape structure and how those responses are influenced by forest harvest, we quantified the relationship between amounts of forest in the landscape at multiple spatial scales and the occurrence of 11 common boreal songbirds in western Newfoundland. The habitat type was assessed at a local scale (25 m diameter area and amounts of forest habitat were measured at neighborhood (300 m and landscape (2500 m scales. We further compared how these relationships differed, depending on whether the landscape had been harvested or not, i.e., the landscape context. Landscape-scale metrics were related to occurrence for 7 of 11 species. For five of these seven, landscape context was also important. Landscape context was not important in models that did not contain a landscape-scale term. In four of five of the models including landscape context, there was an interaction of the term with either landscape or neighborhood effects, indicating that, not only was there an effect of forest harvest at the broad scale, but that effect altered the response of the species to other metrics. For the majority of species, overall occurrence tended to be higher in natural than in harvested landscapes, especially at higher levels of forest cover. Interestingly, for some species, occurrence was relatively similar across levels of forest cover within harvested, but not natural, landscapes. The results suggest some scale-invariance in species' responses to landscape structure, and that some species respond to landscape structure at scales that are broader than those implied by our current knowledge of territorial or dispersal distances. Collectively, the results also suggest that forest management needs to consider not only how local-scale processes might be influenced by local-scale changes in amounts of forest, but also how the broader scale context might interact with those local-scale changes to produce

  20. Sensitivity of boreal forest carbon balance to soil thaw

    Science.gov (United States)

    Goulden, M.L.; Wofsy, S.C.; Harden, J.W.; Trumbore, S.E.; Crill, P.M.; Gower, S.T.; Fries, T.; Daube, B.C.; Fan, S.-M.; Sutton, D.J.; Bazzaz, A.; Munger, J.W.

    1998-01-01

    We used eddy covariance; gas-exchange chambers; radiocarbon analysis; wood, moss, and soil inventories; and laboratory incubations to measure the carbon balance of a 120-year-old black spruce forest in Manitoba, Canada. The site lost 0.3 ?? 0.5 metric ton of carbon per hectare per year (ton C ha-1 year-1) from 1994 to 1997, with a gain of 0.6 ?? 0.2 ton C ha-1 year-1 in moss and wood offset by a loss of 0.8 ?? 0.5 ton C ha-1 year-1 from the soil. The soil remained frozen most of the year, and the decomposition of organic matter in the soil increased 10-fold upon thawing. The stability of the soil carbon pool (~150 tons C ha-1) appears sensitive to the depth and duration of thaw, and climatic changes that promote thaw are likely to cause a net efflux of carbon dioxide from the site.

  1. 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

  2. Belowground Competition Directs Spatial Patterns of Seedling Growth in Boreal Pine Forests in Fennoscandia

    Directory of Open Access Journals (Sweden)

    E. Petter Axelsson

    2014-09-01

    Full Text Available Aboveground competition is often argued to be the main process determining patterns of natural forest regeneration. However, the theory of multiple resource limitation suggests that seedling performance also depends on belowground competition and, thus, that their relative influence is of fundamental importance. Two approaches were used to address the relative importance of above- and below-ground competition on regeneration in a nutrient-poor pine (Pinus sylvestris boreal forest. Firstly, seedling establishment beneath trees stem-girdled 12 years ago show that a substantial proportion of the seedlings were established within two years after girdling, which corresponds to a time when nutrient uptake by tree roots was severely reduced without disrupting water transport to the tree canopy, which consequently was maintained. The establishment during these two years also corresponds to abundances high enough for normal stand replacement. Secondly, surveys of regeneration within forest gaps showed that surrounding forests depressed seedlings, so that satisfactory growth occurred only more than 5 m from forest edges and that higher solar radiation in south facing edges was not enough to mediate these effects. We conclude that disruption of belowground competitive interactions mediates regeneration and, thus, that belowground competition has a strong limiting influence on seedling establishment in these forests.

  3. Total OH Reactivity Measurements in the Boreal Forest

    Science.gov (United States)

    Praplan, A. P.; Hellén, H.; Hakola, H.; Hatakka, J.

    2015-12-01

    INTRODUCTION Atmospheric total OH reactivity (Rtotal) can be measured (Kovacs and Brune, 2001; Sinha et al., 2008) or it can be calculated according to Rtotal = ∑i kOH+X_i [Xi] where kOH+X_i corresponds to the reaction rate coefficient for the reaction of OH with a given compound Xi and [Xi] its concentration. Studies suggest that in some environments a large fraction of missing reactivity, comparing calculated Rtotal with ambient total OH reactivity measurements (Di Carlo et al., 2004; Hofzumahaus et al., 2009). In this study Rtotal has been measured using the Comparative Reactivity Method (Sinha et al., 2008). Levels of the reference compound (pyrrole, C4H5N) are monitored by gas chromatography every 2 minutes and Rtotal is derived from the difference of reactivity between zero and ambient air. RESULTS Around 36 hours of preliminary total OH reactivity data (30 May until 2 June 2015) are presented in Fig. 1. Its range matches previous studies for this site (Nölscher et al., 2012; Sinha et al., 2010) and is similar to values in another pine forest (Nakashima et al., 2014). The setup used during the period presented here has been updated and more recent data will be presented, as well as a comparison with calculated OH reactivity from measured individual species. ACKNOWLEDGEMENTS This work was supported by Academy of Finland (Academy Research Fellowship No. 275608). The authors acknowledge Juuso Raine for technical support. REFERENCES Di Carlo et al. (2004). Science 304, 722-725.Hofzumahaus et al. (2009). Science 324, 1702-1704.Kovacs and Brune (2001). J. Atmos. Chem. 39, 105-122.Nakashima et al. (2014). Atmos. Env. 85, 1-8.Nölscher et al. (2012). Atmos. Chem. Phys. 12, 8257-8270.Sinha et al. (2008). Atmos. Chem. Phys. 8, 2213-2227.Sinha et al. (2010). Environ. Sci. Technol. 44, 6614-6620.

  4. Radiocesium in a Danish pine forest ecosystem

    DEFF Research Database (Denmark)

    Strandberg, M.

    2%. Cesium from Chernobyl is still totally in the upper 5 cm, while almost half of the fallout cesium has penetrated to depths lower than 5 cm. More than 95% of the total amount of Cs-137 is in the soil compartment. The rest is mainly in the trees (3.4%) and vegetation (0.4%), moss and lichen...... of the different components of the forest ecosystem to accumulate radiocesium. OR is defined as the ratio between the content of Cs-137 kg-1 (dry wt.) and the deposition per meter square. In vascular plants, mosses and lichens, OR varied between 0.01 and 0.1 m2/kg. In fungi, it varied between 0...

  5. Considerations on forest ecosystems evolution in the Republic of Moldova

    OpenAIRE

    Petru COCÎRȚĂ; Iurie BEJAN

    2011-01-01

    Certain statistical data on forest ecosystems evolution in Republic of Moldova’s territory in 200 years period are analyzed in the article.  The history of forest fund and ecosystems’ development on the territory between Prut andNistru Rivers and of data presentation methods during different periods of territories’social economical development is summarized. Forest ecosystems development issues instudy and specifically those of forests’ continuity and conservation are extremely important for ...

  6. 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

  7. Modelling carbon and water flows in terrestrial ecosystems in the boreal zone - examples from Oskarshamn

    Energy Technology Data Exchange (ETDEWEB)

    Karlberg, Louise [Stockholm Environment Institute (SEI), Stockholm (Sweden); Gu stafsson, David; Jansson, Per-Erik [Royal Inst. of Technology, Dept. of Land and Water Resources Engineering, Stockholm (Sweden)

    2007-12-15

    Carbon budgets and mean residence times were estimated in four hypothetical ecosystems. The greatest uncertainties in the estimations lie in the calculation of fluxes to and from the field layer. A parametrisation method based on multiple criteria, synthesising a wide range of empirical knowledge on ecosystem behaviour, proved to be useful both in the estimation of unknown parameters, to demonstrate model sensitivity, and to identify processes where our current knowledge is limited. The parameterizations derived from the study of the hypothetical systems were used to estimate site-specific carbon and water budgets for four ecosystems located within the Oskarshamn study-area. Measured soil respiration was used to calibrate the simulations. An analysis of the simulated carbon fluxes indicated that two of the ecosystems, namely the grassland and the spruce forest, were net sources of carbon dioxide, while the alder and the pine forest were net sinks of CO{sub 2}. In the former case, this was interpreted as a result of recent drainage of the organogenic soils and the concurrent increase in decomposition. The results from the study conformed rather well with results from a previous study on carbon budgets from the Oskarshamn study area.

  8. Modelling carbon and water flows in terrestrial ecosystems in the boreal zone - examples from Oskarshamn

    International Nuclear Information System (INIS)

    Carbon budgets and mean residence times were estimated in four hypothetical ecosystems. The greatest uncertainties in the estimations lie in the calculation of fluxes to and from the field layer. A parametrisation method based on multiple criteria, synthesising a wide range of empirical knowledge on ecosystem behaviour, proved to be useful both in the estimation of unknown parameters, to demonstrate model sensitivity, and to identify processes where our current knowledge is limited. The parameterizations derived from the study of the hypothetical systems were used to estimate site-specific carbon and water budgets for four ecosystems located within the Oskarshamn study-area. Measured soil respiration was used to calibrate the simulations. An analysis of the simulated carbon fluxes indicated that two of the ecosystems, namely the grassland and the spruce forest, were net sources of carbon dioxide, while the alder and the pine forest were net sinks of CO2. In the former case, this was interpreted as a result of recent drainage of the organogenic soils and the concurrent increase in decomposition. The results from the study conformed rather well with results from a previous study on carbon budgets from the Oskarshamn study area

  9. Leaf Area Index (LAI Estimation in Boreal Mixedwood Forest of Ontario, Canada Using Light Detection and Ranging (LiDAR and WorldView-2 Imagery

    Directory of Open Access Journals (Sweden)

    Paul Treitz

    2013-10-01

    Full Text Available Leaf Area Index (LAI is an important input variable for forest ecosystem modeling as it is a factor in predicting productivity and biomass, two key aspects of forest health. Current in situ methods of determining LAI are sometimes destructive and generally very time consuming. Other LAI derivation methods, mainly satellite-based in nature, do not provide sufficient spatial resolution or the precision required by forest managers for tactical planning. This paper focuses on estimating LAI from: (i height and density metrics derived from Light Detection and Ranging (LiDAR; (ii spectral vegetation indices (SVIs, in particular the Normalized Difference Vegetation Index (NDVI; and (iii a combination of these methods. For the Hearst Forest of Northern Ontario, in situ measurements of LAI were derived from digital hemispherical photographs (DHPs while remote sensing variables were derived from low density LiDAR (i.e., 1 m−2 and high spatial resolution WorldView-2 data (2 m. Multiple Linear Regression (MLR models were generated using these variables. Results from these analyses demonstrate: (i moderate explanatory power (i.e., R2 = 0.53 for LiDAR height and density metrics that have proven to be related to canopy structure; (ii no relationship when using SVIs; and (iii no significant improvement of LiDAR models when combining them with SVI variables. The results suggest that LiDAR models in boreal forest environments provide satisfactory estimations of LAI, even with narrow ranges of LAI for model calibration. Models derived from low point density LiDAR in a mixedwood boreal environment seem to offer a reliable method of estimating LAI at high spatial resolution for decision makers in the forestry community. This method can be easily incorporated into simultaneous modeling efforts for forest inventory variables using LiDAR.

  10. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-01

    How will regional growth and mortality change with even relatively small climate shifts, even independent of catastrophic disturbances? This question is particularly acute for the North American boreal forest, which is carbon-dense and subject 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 DBH increased even as stand density and basal area declined significantly from 41.3 to 37.5 m2 ha-1. Tree mortality averaged 1.4±0.6% yr-1, with most mortality occurring in medium-sized trees. A combined tree ring chronology constructed from 2001, 2004, and 2012 sampling showed several periods of extreme growth depression, with increased mortality lagging depressed growth by ~5 years. 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. There have been at least one, and probably two, significant recruitment episodes since stand initiation, and we infer that past climate extremes led to significant NOBS mortality still visible in the current forest structure. These results imply that a combination of successional and demographic processes, along with mortality driven by abiotic factors, continue to affect the stand, with significant implications for our understanding of previous work at NOBS and the sustainable management of regional forests.

  12. Evidence and implications of recent and projected climate change in Alaska's forest ecosystems

    Science.gov (United States)

    Wolken, Jane M.; Hollingsworth, Teresa N.; Rupp, T. Scott; Chapin, Stuart III; Trainor, Sarah F.; Barrett, Tara M.; Sullivan, Patrick F.; McGuire, A. David; Euskirchen, Eugénie S.; Hennon, Paul E.; Beever, Erik A.; Conn, Jeff S.; Crone, Lisa K.; D'Amore, David V.; Fresco, Nancy; Hanley, Thomas A.; Kielland, Knut; Kruse, James J.; Patterson, Trista; Schuur, Edward A.G.; Verbyla, David L.; Yarie, John

    2011-01-01

    The structure and function of Alaska's forests have changed significantly in response to a changing climate, including alterations in species composition and climate feedbacks (e.g., carbon, radiation budgets) that have important regional societal consequences and human feedbacks to forest ecosystems. In this paper we present the first comprehensive synthesis of climate-change impacts on all forested ecosystems of Alaska, highlighting changes in the most critical biophysical factors of each region. We developed a conceptual framework describing climate drivers, biophysical factors and types of change to illustrate how the biophysical and social subsystems of Alaskan forests interact and respond directly and indirectly to a changing climate. We then identify the regional and global implications to the climate system and associated socio-economic impacts, as presented in the current literature. Projections of temperature and precipitation suggest wildfire will continue to be the dominant biophysical factor in the Interior-boreal forest, leading to shifts from conifer- to deciduous-dominated forests. Based on existing research, projected increases in temperature in the Southcentral- and Kenai-boreal forests will likely increase the frequency and severity of insect outbreaks and associated wildfires, and increase the probability of establishment by invasive plant species. In the Coastal-temperate forest region snow and ice is regarded as the dominant biophysical factor. With continued warming, hydrologic changes related to more rapidly melting glaciers and rising elevation of the winter snowline will alter discharge in many rivers, which will have important consequences for terrestrial and marine ecosystem productivity. These climate-related changes will affect plant species distribution and wildlife habitat, which have regional societal consequences, and trace-gas emissions and radiation budgets, which are globally important. Our conceptual framework facilitates

  13. 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.

  14. Forest ecosystems: Vegetation, disturbance, and economics: Chapter 5

    Science.gov (United States)

    Littell, Jeremy S.; Hicke, Jeffrey A.; Shafer, Sarah L.; Capalbo, Susan M.; Houston, Laurie L.; Glick, Patty

    2013-01-01

    Forests cover about 47% of the Northwest (NW–Washington, Oregon, and Idaho) (Smith et al. 2009, fig. 5.1, table 5.1). The impacts of current and future climate change on NW forest ecosystems are a product of the sensitivities of ecosystem processes to climate and the degree to which humans depend on and interact with those systems. Forest ecosystem structure and function, particularly in relatively unmanaged forests where timber harvest and other land use have smaller effects, is sensitive to climate change because climate has a strong influence on ecosystem processes. Climate can affect forest structure directly through its control of plan physiology and life history (establishment, individual growth, productivity, and morality) or indirectly through its control of disturbance (fire, insects, disease). As climate changes, many forest processes will be affected, altering ecosystem services such as timber production and recreation. These changes have socioeconomic implications (e.g. for timber economies) and will require changes to current management of forests. Climate and management will interact to determine the forests of the future, and the scientific basis for adaptation to climate change in forests thus depends significantly on how forests will be affected.

  15. Forest ecosystem services and eco-compensation mechanisms in China.

    Science.gov (United States)

    Deng, Hongbing; Zheng, Peng; Liu, Tianxing; Liu, Xin

    2011-12-01

    Forests are a major terrestrial ecosystem providing multiple ecosystem services. However, the importance of forests is frequently underestimated from an economic perspective because of the externalities and public good properties of these services. Forest eco-compensation is a transfer mechanism that serves to internalize the externalities of forest ecosystem services by compensating individuals or companies for the losses or costs resulting from the provision of these services. China's current forest eco-compensation system is centered mainly on noncommercial forest. The primary measures associated with ecosystem services are (1) a charge on destructive activities, such as indiscriminate logging, and (2) compensation for individual or local activities and investments in forest conservation. The Compensation Fund System for Forest Ecological Benefits was first listed in the Forest Law of the People's Republic of China in 1998. In 2004, the Central Government Financial Compensation Fund, an important source for the Compensation Fund for Forest Ecological Benefits, was formally established. To improve the forest eco-compensation system, it is crucial to design and establish compensation criteria for noncommercial forests. These criteria should take both theoretical and practical concerns into account, and they should be based on the quantitative valuation of ecosystem services. Although some initial headway has been made on this task, the implementation of an effective forest eco-compensation system in China still has deficiencies and still faces problems. Implementing classification-based and dynamic management for key noncommercial forests and establishing an eco-compensation mechanism with multiple funding sources in the market economy are the key measures needed to conquer these problems and improve the forest eco-compensation system and China's forestry development in sequence. PMID:21882001

  16. Forest Ecosystem Services and Eco-Compensation Mechanisms in China

    Science.gov (United States)

    Deng, Hongbing; Zheng, Peng; Liu, Tianxing; Liu, Xin

    2011-12-01

    Forests are a major terrestrial ecosystem providing multiple ecosystem services. However, the importance of forests is frequently underestimated from an economic perspective because of the externalities and public good properties of these services. Forest eco-compensation is a transfer mechanism that serves to internalize the externalities of forest ecosystem services by compensating individuals or companies for the losses or costs resulting from the provision of these services. China's current forest eco-compensation system is centered mainly on noncommercial forest. The primary measures associated with ecosystem services are (1) a charge on destructive activities, such as indiscriminate logging, and (2) compensation for individual or local activities and investments in forest conservation. The Compensation Fund System for Forest Ecological Benefits was first listed in the Forest Law of the People's Republic of China in 1998. In 2004, the Central Government Financial Compensation Fund, an important source for the Compensation Fund for Forest Ecological Benefits, was formally established. To improve the forest eco-compensation system, it is crucial to design and establish compensation criteria for noncommercial forests. These criteria should take both theoretical and practical concerns into account, and they should be based on the quantitative valuation of ecosystem services. Although some initial headway has been made on this task, the implementation of an effective forest eco-compensation system in China still has deficiencies and still faces problems. Implementing classification-based and dynamic management for key noncommercial forests and establishing an eco-compensation mechanism with multiple funding sources in the market economy are the key measures needed to conquer these problems and improve the forest eco-compensation system and China's forestry development in sequence.

  17. Environmental Studies in the Boreal Forest Zone: Summer IPY Institute at Central Boreal Forest Reserve, Fedorovskoe, Tver area, Russia (14-28 August, 2007)

    Science.gov (United States)

    Sparrow, E. B.; Kurbatova, Y.; Groisman, P.; Alexeev, V.

    2007-12-01

    The Summer Institute was organized by the International Arctic Research Center (IARC) at the University of Alaska Fairbanks, in collaboration with the A.N. Severtsov Institute for Ecology and Evolution of the Russian Academy of Sciences in Moscow, Russia, and the Central Forest State Nature Biosphere Reserve in Fedorovskoe, Russia. The Institute was arranged as a part of the education/outreach activities of the International Polar Year (IPY) at the University of Alaska and the Northern Eurasia Earth Science Partnership Initiative (NEESPI) and was held in Russia. The Institute provided a unique opportunity for participants to learn about the climate and environment of Northern Eurasia from leading scientists and educators, in a wide spectrum of polar and Earth system science disciplines from meteorology, biology, chemistry, and earth system modeling. Additionally, the Institute attendees observed and participated in the biospheric research activities under the guidance of experienced scientists. During a two-week-interval, the School attendees heard 40 lectures, attended several field trips and participated in three brainstorming Round Table Workshop Sessions devoted to perspectives of the boreal forest zone research and major unresolved problems that it faces. Thirty professors and experts in different areas of climate and biosphere research from Russia, the United States, Germany, Finland, and Japan, shared their expertise in lectures and in round table discussions with the Institute participants. Among the Institute participants there were 31 graduate students/early career scientists from six countries (China, Russia, Estonia, Finland, UK, and the United States) and eight K-12 teachers from Russia. The two groups joined together for several workshop sessions and for the field work components of the Institute. The field work was focused on land-atmosphere interactions and wetland studies in the boreal forest zone. Several field trips in and outside the Forest

  18. Nitrogen export from a boreal stream network following forest harvesting: seasonal nitrate removal and conservative export of organic forms

    Science.gov (United States)

    Schelker, J.; Sponseller, R.; Ring, E.; Högbom, L.; Löfgren, S.; Laudon, H.

    2016-01-01

    Clear-cutting is today the primary driver of large-scale forest disturbance in boreal regions of Fennoscandia. Among the major environmental concerns of this practice for surface waters is the increased mobilization of nutrients, such as dissolved inorganic nitrogen (DIN) into streams. But while DIN loading to first-order streams following forest harvest has been previously described, the downstream fate and impact of these inputs is not well understood. We evaluated the downstream fate of DIN and dissolved organic nitrogen (DON) inputs in a boreal landscape that has been altered by forest harvests over a 10-year period. The small first-order streams indicated substantial leaching of DIN, primarily as nitrate (NO3-) in response to harvests with NO3- concentrations increasing by ˜ 15-fold. NO3- concentrations at two sampling stations further downstream in the network were strongly seasonal and increased significantly in response to harvesting at the mid-sized stream, but not at the larger stream. DIN removal efficiency, Er, calculated as the percentage of "forestry derived" DIN that was retained within the stream network based on a mass-balance model was highest during the snowmelt season followed by the growing season, but declined continuously throughout the dormant season. In contrast, export of DON from the landscape indicated little removal and was essentially conservative. Overall, net removal of DIN between 2008 and 2011 accounted for ˜ 65 % of the total DIN mass exported from harvested patches distributed across the landscape. These results highlight the capacity of nitrogen-limited boreal stream networks to buffer DIN mobilization that arises from multiple clear-cuts within this landscape. Further, these findings shed light on the potential impact of anticipated measures to increase forest yields of boreal forests, such as increased fertilization and shorter forest rotations, which may increase the pressure on boreal surface waters in the future.

  19. 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

  20. Changes in the quality of dissolved organic matter in soil water with time since last fire in a boreal forest

    Science.gov (United States)

    Ide, Jun'ichiro; Ohashi, Mizue; Köster, Kajar; Berninger, Frank; Miura, Ikumi; Makita, Naoki; Yamase, Keitaro; Pumpanen, Jukka

    2016-04-01

    Wildfires strongly influence carbon stocks in boreal forests by inducing combustion of the aboveground and ground biomass. Simultaneously, they greatly influence the quality of dissolved organic matter in the soils, which in turn can alter water and carbon cycles in the forest. However, little information is available on how the quality of dissolved organic matter in boreal forest soils changes with time after forest fire occurred. To examine this, we collected soil water samples in Pinus sylvestris stands located in Finnish Lapland, where fire occurred 6, 46, and 156 years ago, analyzed dissolved organic carbon and inorganic elements concentrations, and then compared them among those three stands. In the assembly, we are going to report the results.

  1. Composition of carbonaceous smoke particles from prescribed burning of a Canadian boreal forest: 1. Organic aerosol characterization by gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Mazurek, M.A.; Laterza, C.; Newman, L.; Daum, P. [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; Winstead, E.L. [Science Applications International Corporation, Hampton, VA (United States)

    1995-06-01

    In this study we examine the molecular organic constituents (C8 to C40 lipid compounds) collected as smoke particles from a Canadian boreal forest prescribed burn. Of special interest are (1) the molecular identity of polar organic aerosols, and (2) the amount of polar organic matter relative to the total mass of aerosol particulate carbon. Organic extracts of smoke aerosol particles show complex distributions of the lipid compounds when analyzed by capillary gas chromatography/mass spectrometry. The molecular constituents present as smoke aerosol are grouped into non-polar (hydrocarbons) and polar {minus}2 oxygen atoms) subtractions. The dominant chemical species found in the boreal forest smoke aerosol are unaltered resin compounds (C20 terpenes) which are abundant in unburned conifer wood, plus thermally altered wood lignins and other polar aromatic hydrocarbons. Our results show that smoke aerosols contain molecular tracers which are related to the biofuel consumed. These smoke tracers can be related structurally back to the consumed softwood and hardwood vegetation. In addition, combustion of boreal forest materials produces smoke aerosol particles that are both oxygen-rich and chemically complex, yielding a carbonaceous aerosol matrix that is enriched in polar substances. As a consequence, emissions of carbonaceous smoke particles from large-scale combustion of boreal forest land may have a disproportionate effect on regional atmospheric chemistry and on cloud microphysical processes.

  2. Spectral contribution of understory to forest reflectance in a boreal site: an analysis of EO-1 Hyperion data

    Czech Academy of Sciences Publication Activity Database

    Rautianien, M.; Lukeš, Petr

    2015-01-01

    Roč. 171, dec (2015), s. 98-104. ISSN 0034-4257 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : forest reflectance model * hyperspectral * boreal * leaf area index * understory Subject RIV: EH - Ecology, Behaviour Impact factor: 6.393, year: 2014

  3. Occurrence and Distribution of Synthetic Organic Substances in Boreal Coniferous Forest Soils Fertilized with Hygienized Municipal Sewage Sludge

    OpenAIRE

    Mats Tysklind; Kenneth Sahlén; Richard Lindberg

    2013-01-01

    The occurrence and distribution of synthetic organic substances following application of dried and granulated (hygienized) municipal sewage sludge in Swedish boreal coniferous forests were investigated. Elevated concentrations of triclosan (TCS), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs) were detected in the humus layer. Concentrations of ethinyl estradiol (EE2), norfloxacin, ciprofloxacin, ofloxacin (FQs), and polyaromatic hydrocarbons (PAHs) were not signi...

  4. Soil moisture sensitivity of autotrophic and heterotrophic forest floor respiration in boreal xeric pine and mesic spruce forests

    Science.gov (United States)

    Ťupek, Boris; Launiainen, Samuli; Peltoniemi, Mikko; Heikkinen, Jukka; Lehtonen, Aleksi

    2016-04-01

    Litter decomposition rates of the most process based soil carbon models affected by environmental conditions are linked with soil heterotrophic CO2 emissions and serve for estimating soil carbon sequestration; thus due to the mass balance equation the variation in measured litter inputs and measured heterotrophic soil CO2 effluxes should indicate soil carbon stock changes, needed by soil carbon management for mitigation of anthropogenic CO2 emissions, if sensitivity functions of the applied model suit to the environmental conditions e.g. soil temperature and moisture. We evaluated the response forms of autotrophic and heterotrophic forest floor respiration to soil temperature and moisture in four boreal forest sites of the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) by a soil trenching experiment during year 2015 in southern Finland. As expected both autotrophic and heterotrophic forest floor respiration components were primarily controlled by soil temperature and exponential regression models generally explained more than 90% of the variance. Soil moisture regression models on average explained less than 10% of the variance and the response forms varied between Gaussian for the autotrophic forest floor respiration component and linear for the heterotrophic forest floor respiration component. Although the percentage of explained variance of soil heterotrophic respiration by the soil moisture was small, the observed reduction of CO2 emissions with higher moisture levels suggested that soil moisture response of soil carbon models not accounting for the reduction due to excessive moisture should be re-evaluated in order to estimate right levels of soil carbon stock changes. Our further study will include evaluation of process based soil carbon models by the annual heterotrophic respiration and soil carbon stocks.

  5. Function and dynamics of woody debris in boreal forest streams

    OpenAIRE

    Dahlström, Niklas

    2005-01-01

    The work in this thesis deals with (1) the effects of woody debris on stream channel morphology and retention of organic material, and (2) the dynamics of woody debris and its relation to riparian forest history and composition. The studied stream reaches are situated in mature, productive forests in the boreal zone of Sweden. Wood variables were important predictors of the frequency of debris dams, pool area, the proportion of pools formed by wood, and variation in the bankfull channel width...

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

    Science.gov (United States)

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

    2015-10-01

    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 concentration profiles and the surface layer profile method connected to the Monin-Obukhov similarity theory. In total fluxes that differed significantly from zero on a monthly basis were observed for 13 out of 27 measured masses. Monoterpenes had the highest net emission in all seasons and statistically significant positive fluxes were detected from March until October. Other important compounds emitted were methanol, ethanol+formic acid, acetone and isoprene+methylbutenol. Oxygenated VOCs showed also deposition fluxes that were statistically different from zero. Isoprene+methylbutenol and monoterpene fluxes followed well the traditional isoprene algorithm and the hybrid algorithm, respectively. Emission potentials of monoterpenes were largest in late spring and autumn which was possibly driven by growth processes and decaying of soil litter, respectively. Conversely, largest emission potentials of isoprene+methylbutenol were found in July. Thus, we concluded that most of the emissions of m/z 69 at the site consisted of isoprene that originated from broadleaved trees. Methanol had deposition fluxes especially before sunrise. This can be connected to water films on surfaces. Based on this assumption, we were able to build an empirical algorithm for bi-directional methanol exchange that described both emission term and deposition term. Methanol emissions were highest in May and June and deposition level increased towards autumn, probably as a result of increasing relative humidity levels leading to

  7. 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.

  8. 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%.

  9. Radiative forcing impacts of boreal forest biofuels: a scenario study for Norway in light of albedo.

    Science.gov (United States)

    Bright, Ryan M; Strømman, Anders Hammer; Peters, Glen P

    2011-09-01

    Radiative forcing impacts due to increased harvesting of boreal forests for use as transportation biofuel in Norway are quantified using simple climate models together with life cycle emission data, MODIS surface albedo data, and a dynamic land use model tracking carbon flux and clear-cut area changes within productive forests over a 100-year management period. We approximate the magnitude of radiative forcing due to albedo changes and compare it to the forcing due to changes in the carbon cycle for purposes of attributing the net result, along with changes in fossil fuel emissions, to the combined anthropogenic land use plus transport fuel system. Depending on albedo uncertainty and uncertainty about the geographic distribution of future logging activity, we report a range of results, thus only general conclusions about the magnitude of the carbon offset potential due to changes in surface albedo can be drawn. Nevertheless, our results have important implications for how forests might be managed for mitigating climate change in light of this additional biophysical criterion, and in particular, on future biofuel policies throughout the region. Future research efforts should be directed at understanding the relationships between the physical properties of managed forests and albedo, and how albedo changes in time as a result of specific management interventions. PMID:21797227

  10. Using InSAR Coherence to Map Stand Age in a Boreal Forest

    Directory of Open Access Journals (Sweden)

    Naiara Pinto

    2012-12-01

    Full Text Available The interferometric coherence parameter γ estimates the degree of correlation between two Synthetic Aperture Radar (SAR images and can be influenced by vegetation structure. Here, we investigate the use of repeat-pass interferometric coherence γ to map stand age, an important parameter for the study of carbon stocks and forest regeneration. In August 2009 NASA’s L-band airborne sensor UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar acquired zero-baseline data over Quebec with temporal separation ranging between 45 min and 9 days. Our analysis focuses on a 66 km2 managed boreal forest and addresses three questions: (i Can coherence from L-band systems be used to model forest age? (ii Are models sensitive to weather events and temporal baseline? and (iii How is model accuracy impacted by the spatial scale of analysis? Linear regression models with 2-day baseline showed the best results and indicated an inverse relationship between γ and stand age. Model accuracy improved at 5 ha scale (R2 = 0.75, RMSE = 5.3 as compared to 1 ha (R2 = 0.67, RMSE = 5.8. Our results indicate that coherence measurements from L-band repeat-pass systems can estimate forest age accurately and with no saturation. However, empirical model relationships and their accuracy are sensitive to weather events, temporal baseline, and spatial scale of analysis.

  11. Nesting ecology of boreal forest birds following a massive outbreak of spruce beetles

    Science.gov (United States)

    Matsuoka, S.M.; Handel, C.M.

    2007-01-01

    We studied breeding dark-eyed juncos (Junco hyemalis), yellow-rumped warblers (Dendroica coronata), and spruce-nesting birds from 1997 to 1998 among forests with different levels of spruce (Picea spp.) mortality following an outbreak of spruce beetles (Dendroctonus rufipennis) in Alaska, USA. We identified species using live and beetle-killed spruce for nest sites and monitored nests to determine how the outbreak influenced avian habitat selection and reproduction. We tested predictions that 1) nesting success of ground-nesting juncos would increase with spruce mortality due to proliferation of understory vegetation available to conceal nests from predators, 2) nesting success of canopy-nesting warblers would decrease with spruce mortality due to fewer live spruce in which to conceal nests, and 3) both species would alter nest-site selection in response to disturbance. Juncos did not benefit from changes in understory vegetation; nesting success in highly disturbed stands (46%) was comparable to that in undisturbed habitats throughout their range. In stands with low spruce mortality, nesting success of juncos was low (5%) and corresponded with high densities of red squirrels (Tamiasciurus hudsonicus). Yellow-rumped warblers nested exclusively in spruce, but success did not vary with spruce mortality. As disturbance increased, nesting warblers switched from selecting forest patches with high densities of live white spruce (Picea glauca) to patches with beetle-killed spruce. Warblers also placed nests in large-diameter live or beetle-killed spruce, depending on which was more abundant in the stand, with no differences in nesting success. Five of the 12 other species of spruce-nesting birds also used beetle-killed spruce as nest sites. Because beetle-killed spruce can remain standing for >50 years, even highly disturbed stands provide an important breeding resource for boreal forest birds. We recommend that boreal forest managers preserve uncut blocks of infested

  12. 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 avian populations. The intended applications of these models are land use planning and avian conservation across the nearctic boreal forest. In this essay, we present a description of the extensive collection of point count survey data assembled by the Project, and the library of spatial covariates used for modeling. We show how it is possible to account for a number of nuisance variables related to differences in survey protocol among source data sets and make some preliminary suggestions as to how future surveys could be standardized. We present a distance-sampling approach used to convert standardized point count data to density estimates, which we illustrate by providing habitat-specific densities and total population estimates for one species in a part of western Canada. We also illustrate the use of Classification and Regression Trees to develop species niche models from the standardized data. We conclude with a discussion of the need for a monitoring program for boreal birds in Canada, the role of predictive statistical models in developing such a program, and how monitoring could be related to boreal bird conservation through

  13. Vegetation Feedbacks Explain Recent High-latitude Summer Warming in Alaskan Arctic and Boreal Ecosystems

    Science.gov (United States)

    Chapin, F. S.; Beringer, J.; Copass, C.; Epstein, H.; Lloyd, A.; Lynch, A.; McGuire, A. D.; Sturm, M.

    2002-12-01

    Although General Circulation Models predict the observed winter and spring warming at high latitudes, there is no obvious physical mechanism in the climate system that can account for the significant increase in summer temperatures that has occurred at high latitudes during the past 30 years. We demonstrate that vegetation-induced feedbacks in snow properties and summer energy exchange with the atmosphere explain this recent summer warming. A combination of stand-age reconstructions, repeat photography, and satellite measures of vegetation greenness demonstrate an expansion of the distribution and an infilling of shrubs in moist tundra and of trees in forest tundra. These vegetation changes increase the depth and thermal resistance of the snow pack, causing a 3oC increase in winter soil temperature and an increase in winter decomposition and nutrient mineralization, which enhance plant growth. These vegetation changes also increase summer heat transport to the atmosphere by increasing radiation absorption (lower albedo) and the proportion of absorbed energy that is transferred to the atmosphere as sensible heat. The resulting increase in atmospheric heating, on a unit-area basis, is similar to effects of a doubling of atmospheric carbon dioxide or a 2% change in solar constant, such as occurred at the last glacial-interglacial boundary. Simulations with the regional climate model ARCSyM indicate that a change from shrubless tundra to shrub-dominated tundra on the North Slope of Alaska would increase July mean temperature by 1.5 to 3.5 degrees C, with the warming effects extending south into the boreal forest of interior Alaska. If these vegetation feedbacks to regional warming are widespread, as suggested by indigenous knowledge and the satellite record, they are of sufficient magnitude to explain the summer warming that has recently been observed in northern Alaska and other regions of the circumpolar Arctic.

  14. Spatial patterns of ecosystem carbon residence time in Chinese forests

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Capacity of carbon sequestration in forest ecosystem largely depends on the trend of net primary production (NPP) and the length of ecosystem carbon residence time. Retrieving spatial patterns of ecosystem carbon residence time is important and necessary for accurately predicting regional carbon cycles in the future. In this study, a data-model fusion method that combined a process-based regional carbon model (TECO-R) with various ground-based ecosystem observations (NPP, biomass, and soil organic carbon) and auxiliary data sets (NDVI, meteorological data, and maps of vegetation and soil texture) was applied to estimate spatial patterns of ecosystem carbon residence time in Chinese forests at steady state. In the data-model fusion, the genetic algorithm was used to estimate the optimal model parameters related with the ecosystem carbon residence time by minimizing total deviation between modeled and observed values. The results indicated that data-model fusion technology could effectively retrieve model parameters and simulate carbon cycling processes for Chinese forest ecosystems. The estimated carbon residence times were highly heterogenous over China, with most of regions having values between 24 and 70 years. The deciduous needleleaf forest and the evergreen needleleaf forest had the highest averaged carbon residence times (73.8 and 71.3 years, respectively), the mixed forest and the deciduous broadleaf forest had moderate values (38.1 and 37.3 years, respectively), and the evergreen broadleaf forest had the lowest value (31.7 years). The averaged carbon residence time of forest ecosystems in China was 57.8 years.

  15. [Forest ecosystem service and its evaluation in China].

    Science.gov (United States)

    Fang, Jin; Lu, Shaowei; Yu, Xinxiao; Rao, Liangyi; Niu, Jianzhi; Xie, Yuanyuan; Zhag, Zhenming

    2005-08-01

    Facing the relative lag of forest ecosystem service and estimation in China, this paper proposed to quickly carry out the research on the evaluation of forest ecosystem service. On the basis of the classification of forest ecosystem types in China, the service of artificial and semi-artificial forest ecosystems was investigated, which was divided into eight types, i.e., timber and other products, recreation and eco-tourism, water storage, C fixation and O2 release, nutrient cycling, air quality purifying, erosion control, and habitat provision. According to the assessment index system for global ecosystem service proposed by Costanza et al., a series of assessment index system suitable for Chinese forest ecosystem service was set up, by which, the total value of forest ecosystem service in China was estimated to be 30 601.20 x 10(8) yuan x yr(-1), including direct and indirect economic value about 1 920.23 x 10(8) and 28 680.97 x 10(8) yuan x yr(-1), respectively. The indirect value was as 14.94 times as the direct one. The research aimed to bring natural resources and environment factors into the account system of national economy quickly, and to realize the green GDP at last, which would be helpful to realize sustainable development and environment protection. PMID:16262073

  16. 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.

  17. Effect of small mammals on forest ecosystem structure and function

    International Nuclear Information System (INIS)

    Information is presented on the possible impacts of small mammals in temperate forest ecosystems. Studies reviewed here suggest that small mammals have a minimal role in influencing forest ecosystem processes. Their effect on energy flow patterns and nutrient dynamics of forests appears minimal in view of the relatively small amounts of energy and nutrients acted upon by small mammals. Significant effects of small mammals as herbivores and granivores tend to be limited to early successional stages when trees are young and most susceptible to damage and when seed and seedling mortality are more likely to be of consequence. They appear to have a minimal impact on vegetation in mature forests. Small mammals are a major constituent in the diet of many avian and mammalian predators and may be important in maintaining higher trophic levels in forests. They may exert some influence on forest floor invertebrates, but the long-term effects of this action on forests are not understood

  18. Vertical Distribution of Atmospheric Pollution Lead in Swedish Boreal Forest Soils

    International Nuclear Information System (INIS)

    In order to understand the fate of anthropogenic lead (Pb)pollution in boreal forest soils, and to predict future trends, it is important to know where in the soil the pollution Pb is accumulated and how large the pollution and natural Pb inventories are in different soil horizons. We combined stable Pb isotope (206Pb/207Pb ratios) and concentration analyses to study Pb in podzol profiles and mor samples from old-growth forest stands at seven sites distributed from southern to northern Sweden. Additional samples were taken from managed forests, and from an agricultural field, to give some idea of the effects of land-use. Pb concentrations are typically 60-100 μg g-1 dry mass in the mor layer in southern Sweden and about 30 μg g-1 in northern Sweden. Pb isotope analyses show that virtually all of this Pb is pollution Pb. The isotope composition also shows that pollution Pb has penetrated downwards between 20-60 cm in the forest soils. The total pollution Pb inventories vary between 0.7-3.0 g m-2 ground surface, with larger inventories in southern compared to northern Sweden. Although the highest Pb concentrations occur in the mor layer, the largest inventories of pollution Pb are found in the Bs-horizon. The limited investigation of Pb distribution and inventories in soils from managed forests did not point to any major difference compared to the old-growth forests. The agricultural field revealed, however, a completely deviating Pb profile with all pollution Pb evenly distributed in the 20 cm thick top-soil

  19. Estimation of autotrophic soil respiration in a boreal forest using three different approaches

    Science.gov (United States)

    Kulmala, Liisa; Pumpanen, Jukka; Heinonsalo, Jussi

    2016-04-01

    It is generally challenging to separate autotrophic and heterotrophic soil respiration. The reason for these difficulties is connected with the intimate interaction of the key processes in soil. Root-associated microbes practically colonize the whole soil volume while decomposition processes occur in the same matrix. Therefore, autotrophic and heterotrophic processes cannot be separated in natural systems. However, there are several methods that can be used to better understand the dynamics of these two. A classical method is called 'trenching' where a trench is dug around a known volume of soil and the roots entering the soil are cut from the living trees thus blocking the C flow from them. The second way to separate autotrophic and heterotrophic respiration relies on the difference in the isotopic signature (13C) of plant-derived or decomposition-derived CO2. The third way to separate the sources is to study the differences in the short- and long-term temperature dependencies in CO2 soil emissions. This is possible especially in boreal forests where the biological activity has a strong seasonal cycle. We compared these three methods in an experiment conducted in a southern boreal middle-aged Scots pine stand in Finland. Our data provides a unique possibility to critically evaluate current methods for estimating autotrophic and heterotrophic soil respiration. The knowledge is needed to study further plant physiology and plant-microbe interactions in soil.

  20. 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.

  1. BOREAS TE-9 In Situ Diurnal Gas Exchange of NAS Boreal Forest Stands

    Science.gov (United States)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Coyea, Marie; Dang, Qinglai

    2000-01-01

    The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. The purpose of the BOREAS TE-09 study was threefold: 1) to provide in situ gas exchange data that will be used to validate models of photosynthetic responses to light, temperature, and carbon dioxide (CO2); 2) to compare the photosynthetic responses of different tree crown levels (upper and lower); and 3) to characterize the diurnal water potential curves for these sites to get an indication of the extent to which soil moisture supply to leaves might be limiting photosynthesis. The gas exchange data of the BOREAS NSA were collected to characterize diurnal gas exchange and water potential of two canopy levels of five boreal canopy cover types: young jack pine, old jack pine, old aspen, lowland old black spruce, and upland black spruce. These data were collected between 27-May-1994 and 17-Sep-1994. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

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

    Science.gov (United States)

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

    2012-09-01

    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 8.9 ± 3.2 ppt ppb-1 CO for methanol to 0.007 ± 0.004 ppt ppb-1 CO for cyclopentane. The ratios are in good to excellent agreement with recent literature values. Using the GEOS-Chem global 3-D chemical transport model (CTM) we show the influence of biomass burning on the global distributions of benzene, toluene, ethene and propene (species considered generally as indicative tracers of anthropogenic activity). Using our derived emission ratios and the GEOS-Chem CTM, we show that biomass burning can be the largest fractional contributor to observed benzene, toluene, ethene and propene in many global locations. The widespread biomass burning contribution to atmospheric benzene, a heavily regulated air pollutant, suggests that pragmatic approaches are needed when setting air quality targets as tailpipe and solvent emissions continue to decline. We subsequently determine the extent to which the 28 Global WMO-GAW stations worldwide are influenced by biomass burning sourced benzene, toluene, ethene and propene when compared to their exposure to anthropogenic emissions.

  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. 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

  5. How have past fire disturbances contributed to the current carbon balance of boreal ecosystems?

    Science.gov (United States)

    Yue, C.; Ciais, P.; Zhu, D.; Wang, T.; Peng, S. S.; Piao, S. L.

    2016-02-01

    Boreal fires have immediate effects on regional carbon budgets by emitting CO2 into the atmosphere at the time of burning, but they also have legacy effects by initiating a long-term carbon sink during post-fire vegetation recovery. Quantifying these different effects on the current-day pan-boreal (44-84° N) carbon balance and quantifying relative contributions of legacy sinks by past fires is important for understanding and predicting the carbon dynamics in this region. Here we used the global dynamic vegetation model ORCHIDEE-SPITFIRE (Organising Carbon and Hydrology In Dynamic Ecosystems - SPread and InTensity of FIRE) to attribute the contributions by fires in different decades between 1850 and 2009 to the carbon balance of 2000-2009, taking into account the atmospheric CO2 change and climate change since 1850. The fire module of ORCHIDEE-SPITFIRE was turned off for each decade in turn and was also turned off before and after the decade in question in order to model the legacy carbon trajectory by fires in each past decade. We found that, unsurprisingly, fires that occurred in 2000-2009 are a carbon source (-0.17 Pg C yr-1) for the carbon balance of 2000-2009, whereas fires in all decades before 2000 contribute carbon sinks with a collective contribution of 0.23 Pg C yr-1. This leaves a net fire sink effect of 0.06 Pg C yr-1, or 6.3 % of the simulated regional carbon sink (0.95 Pg C yr-1). Further, fires with an age of 10-40 years (i.e., those that occurred during 1960-1999) contribute more than half of the total sink effect of fires. The small net sink effect of fires indicates that current-day fire emissions are roughly balanced out by legacy sinks. The future role of fires in the regional carbon balance remains uncertain and will depend on whether changes in fires and associated carbon emissions will exceed the enhanced sink effects of previous fires, both being strongly affected by global change.

  6. The influence of vegetation and soil characteristics on active-layer thickness of permafrost soils in boreal forest.

    Science.gov (United States)

    Fisher, James P; Estop-Aragonés, Cristian; Thierry, Aaron; Charman, Dan J; Wolfe, Stephen A; Hartley, Iain P; Murton, Julian B; Williams, Mathew; Phoenix, Gareth K

    2016-09-01

    Carbon release from thawing permafrost soils could significantly exacerbate global warming as the active-layer deepens, exposing more carbon to decay. Plant community and soil properties provide a major control on this by influencing the maximum depth of thaw each summer (active-layer thickness; ALT), but a quantitative understanding of the relative importance of plant and soil characteristics, and their interactions in determine ALTs, is currently lacking. To address this, we undertook an extensive survey of multiple vegetation and edaphic characteristics and ALTs across multiple plots in four field sites within boreal forest in the discontinuous permafrost zone (NWT, Canada). Our sites included mature black spruce, burned black spruce and paper birch, allowing us to determine vegetation and edaphic drivers that emerge as the most important and broadly applicable across these key vegetation and disturbance gradients, as well as providing insight into site-specific differences. Across sites, the most important vegetation characteristics limiting thaw (shallower ALTs) were tree leaf area index (LAI), moss layer thickness and understory LAI in that order. Thicker soil organic layers also reduced ALTs, though were less influential than moss thickness. Surface moisture (0-6 cm) promoted increased ALTs, whereas deeper soil moisture (11-16 cm) acted to modify the impact of the vegetation, in particular increasing the importance of understory or tree canopy shading in reducing thaw. These direct and indirect effects of moisture indicate that future changes in precipitation and evapotranspiration may have large influences on ALTs. Our work also suggests that forest fires cause greater ALTs by simultaneously decreasing multiple ecosystem characteristics which otherwise protect permafrost. Given that vegetation and edaphic characteristics have such clear and large influences on ALTs, our data provide a key benchmark against which to evaluate process models used to predict

  7. Water balance dynamics of a boreal forest watershed: White Gull Creek basin, 1994-1996

    Science.gov (United States)

    Nijssen, Bart; Lettenmaier, Dennis P.

    2002-11-01

    Field measurements from the Boreal Ecosystem-Atmosphere Study (BOREAS) were combined to calculate the water balance of the White Gull Creek basin for the three year period 1994-1996. Evapotranspiration was mapped from the observations made at the BOREAS flux towers to the basin using a simple evaporation model with a bulk canopy resistance based on tower observations. Runoff ratios were low, and evapotranspiration accounted for most of the precipitation over the area. The accumulated storage change, over the 3 year period, was 47 mm or 3.4% of the total precipitation, but precipitation exceeded the sum of discharge and evapotranspiration by 80 mm or 15% of the precipitation in 1994. Five possible explanations for the discrepancy in the water balance are identified, with the most likely cause an underestimation of the evapotranspiration in 1994, especially during periods when the basin is wet.

  8. Changes to Stream Water and Soil Temperature Regimes Pre and Post Forest Harvesting in Low Order Boreal Forest Watersheds.

    Science.gov (United States)

    Allan, C. J.; Najaf, P.; Mackereth, R.; Steedman, R.

    2014-12-01

    Soil and stream water temperatures were logged at 15 minute intervals (1995-2008) pre and post logging at four intensively monitored zero order boreal forest watersheds in NW Ontario, Canada. Trends in post logging changes to daily average, maximum and diurnal ranges in stream water and soil temperatures are presented. Changes to the soil temperature regime were found to be spatially variable and dependent upon aspect, hill slope position and soil moisture regime. In general, soil temperature displayed a hysteretic behavior in relation to reference sites during the post logging period with significantly warmer spring and summer temperatures and similar autumn temperatures. Stream water temperature appeared to be controlled by post logging surface soil temperatures (0-15 cm) as opposed to deeper (30-40 cm) soil temperatures during the pretreatment period. Results are compared to previous studies and implications for soil microbial processes and stream benthic communities are highlighted.

  9. Flows of Chemical Substances in Latvian Pine Forests Ecosystems

    OpenAIRE

    Tērauda, Evija

    2008-01-01

    FLOWS OF CHEMICAL SUBSTANCES IN LATVIAN PINE FORESTS ECOSYSTEMS Annotation As a basis of the study, data from integrated monitoring stations of Latvia have been used. The objective of the study is to study turnover of substances in ecosystems of pine forests in the boreo-nemoral zone. The results of the study showed that the mean concentration of studied elements (except Pb) increased in the order: bulk precipitation

  10. Soil-plant transfer factors in forest ecosystems

    International Nuclear Information System (INIS)

    In an Austrian monitoring programme of 137Cs behaviour in forest ecosystem in 1993, about 80 soil samples and 200 plant samples were collected in the Weinsberger Wald (spruce forest ecosystem in Lower Austria). The soil contamination was determined by analysing thin-layer profiles and pooled samples. In addition to an overview of 137Cs contamination of vegetation, special topics such as seasonality and cycling phenomena were investigated. 6 refs, 2 figs

  11. Expert Group and Workshop on Valuation of Forest Ecosystem Services

    OpenAIRE

    BARREDO CANO JOSE IGNACIO; SNOWDON Pat; VENTRUBOVA Katerina

    2015-01-01

    Forests create multiple benefits for the society, providing renewable raw materials and play an important role in human wellbeing, biological diversity, the global carbon cycle, water balance, erosion control, combating desertification and the prevention of natural hazards, among others. Forests contribute to environmental stability, economic prosperity and offer social, ecosystem and recreational services. The improve the knowledge about ecosystem services, its value and natural capital allo...

  12. Spider assemblages in the overstory, understory, and ground layers of managed stands in the western boreal mixedwood forest of Canada.

    Science.gov (United States)

    Pinzon, Jaime; Spence, John R; Langor, David W

    2011-08-01

    Logging is the main human disturbance in the boreal forest; thus, understanding the effects of harvesting practices on biodiversity is essential for a more sustainable forestry. To assess changes in spider composition because of harvesting, samples were collected from three forest layers (overstory, understory, and ground) of deciduous and conifer dominated stands in the northwestern Canadian boreal mixedwood forest. Spider assemblages and feeding guild composition were compared between uncut controls and stands harvested to 20% retention. In total, 143 spider species were collected, 74 from the ground, 60 from the understory, and 71 from the overstory, and species composition of these three pools differed considerably among layers. Distinctive spider assemblages were collected from the canopy of each forest cover type but these were only slightly affected by harvesting. However, logging had a greater impact on the species composition in the understory and ground layers when compared with unharvested controls. Guild structure differed among layers, with wandering and sheet-weaving spiders dominant on the ground while orb-weaving and ambush spiders were better represented in the understory and overstory, respectively. Given the ecological importance of spiders and the expectation of faunal changes with increased harvesting, further efforts toward the understanding of species composition in higher strata of the boreal forest are needed. PMID:22251680

  13. Mammalian Herbivores in the Boreal Forests: Their Numerical Fluctuations and Use by Man

    Directory of Open Access Journals (Sweden)

    Leonid Baskin

    1998-12-01

    Full Text Available Within the boreal zone, there are about 50 native mammalian herbivore species that belong to the orders Artiodactyla, Rodentia, and Lagomorpha. Of these species, 31 occur in the Nearctic and 24 in the Palaearctic. Only six species occur in both regions. Species of the family Cervidae have probably been, and still are, the most important group for man, as they provide both meat and hides. Pelts from squirrels, muskrats, and hares were commercially harvested at the beginning of the century, but have less value today. The semi-domestic reindeer in the Palaearctic produces meat and hides on a commercial basis. It is also used for milking, to a limited extent, as is the semi-domestic moose in Russia. The Siberian musk deer is used for its musk and is raised in captivity in China. All species heavier than 1 kg are utilized by man, those with a body mass in the range 1 kg - 1 hg are sometimes used, and species lighter than 1 hg are rarely used. Here, we review the numerical fluctuations in terms of periodicity and amplitude, based on an extensive data set found in the literature, especially from the former Soviet Union. Current understanding of the underlying factors behind the population fluctuations is briefly reviewed. Management and conservation aspects of the mammalian herbivores in the boreal zone are also discussed. We conclude that there is a challenge to manage the forests for the mammalian herbivores, but there is also a challenge to manage the populations of mammalian herbivores for the forests.

  14. 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.

  15. Temporal variations in the carbon budget of forest ecosystems in Spain

    OpenAIRE

    Rodríguez Murillo, Juan Carlos

    1997-01-01

    Temperate and boreal forests of the Northern Hemisphere have recently been identified as important carbon sinks. Accurate calculation of forest carbon budget and appraisal of the temporal variations of forest net carbon fluxes are important topics to elucidate the ‘‘missing sink’’ question and to follow up the changing carbon dynamics in forests. In this article, recent carbon budgets of the forests of a region in northern Spain have been calculated using data from forest in...

  16. 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

  17. Reindeer grazing in subarctic boreal forest - influences on the soil carbon dynamics

    Science.gov (United States)

    Koster, Kajar; Berninger, Frank; Köster, Egle; Pumpanen, Jukka

    2015-04-01

    Reindeer (Rangifer tarandus L.) are the most important large mammalian herbivores in the northern ecosystems , which have many effects on plant diversity, soil nutrient cycling and soil organic matter decomposition. Changes caused by reindeer in vegetation have indirect effects on physical features of the soil e.g. soil microclimate, root biomass and also on soil C dynamics. Earlier, the role of reindeer grazing in ground vegetation dynamics and in soil carbon (C) dynamics has been mostly investigated in open tundra heaths. The objectives of this study were to examine if and how the reindeer grazing (and the possible temperature changes in soil caused by heavy grazing) is affecting the soil C dynamics (CO2 efflux from the soil, C storage in soil, microbial biomass in the soil). In a field experiment in Finnish Lapland, in Värriö Strict Nature Reserve (67° 46' N, 29° 35' E) we have assessed the changes occurring in above- and belowground biomasses, and soil C dynamics (CO2 efflux, soil C content, soil microbial biomass C) among areas grazed and ungrazed by reindeer. Our study areas are located in the northern boreal subarctic coniferous forest at the zone of the last intact forest landscapes in Fennoscandia, where large areas of relatively undisturbed subarctic Scots pine (Pinus sylvestris L.) forests can still be found. The sample plots located in the Värriö Strict Nature Reserve (10 sample plots in total established in year 2013) are situated along the borderline between Finland and Russia, where the ungrazed area was excluded from the reindeer grazing already in 1918, to prevent the Finnish reindeer from going to the Russian side and there are not many reindeer on Russian side of the area. To characterize the stands we have established circular sample plots on areas with a radius of 11.28 m, where different tree characteristics were measured (diameter at 1.3 m, height, height of a tree, crown height, crown diameter, stand age, etc.). On every sample plot

  18. 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.

  19. Survival of Adult Songbirds in Boreal Forest Landscapes Fragmented by Clearcuts and Natural Openings

    Directory of Open Access Journals (Sweden)

    Darroch M. Whitaker

    2008-06-01

    Full Text Available There exists little information on demographic responses of boreal songbirds to logging. We conducted a 4-yr (2003-2006 songbird mark-recapture study in western Newfoundland, where land cover is a naturally heterogeneous mosaic of productive spruce-fir forest, stunted taiga, and openings such as bogs, fens, and riparian zones. We compared apparent survival and rate of transience for adults of 14 species between areas having forests fragmented primarily by either natural openings or 3-7 yr-old clearcuts. Data were collected on three landscape pairs, with birds being marked on three 4-6 ha netting sites on each landscape (total = 18 netting sites. Survival rates were estimated using multi-strata mark-recapture models with landscape types specified as model strata. Landscape type was retained in the best model for only two species, Ruby-crowned Kinglet and Yellow-rumped Warbler, in both cases indicating lower apparent survival in landscapes having clearcuts. Though parameter estimates suggested lower survival in clearcut landscapes for several species, meta-analysis across all species detected no general difference between landscape types. Further, we did not detect any relation between landscape differences in survival and a species' habitat affinity, migratory strategy, or the proportion of transients in its population. Although sensitivity to logging was limited, we observed high interspecific variation in rates of breeding season apparent survival (48% [Dark-eyed Junco] to 100% [several species], overwinter apparent survival (0.3% [Ruby-crowned Kinglet] to 86.5% [Gray Jay], and transience (≈0% [several species] to 61% [Ruby-crowned Kinglet in clearcut landscapes]. For Lincoln's and White-throated Sparrows, over-winter apparent survival was >2× higher for males than females, and rate of transience was > 8× higher for White-throated Sparrow males than females. Moderately male-biased sex ratios suggested that both lower mortality and higher

  20. A tool for assessing ecological status of forest ecosystem

    Science.gov (United States)

    Rahman Kassim, Abd; Afizzul Misman, Muhammad; Azahari Faidi, Mohd; Omar, Hamdan

    2016-06-01

    Managers and policy makers are beginning to appreciate the value of ecological monitoring of artificially regenerated forest especially in urban areas. With the advent of more advance technology in precision forestry, high resolution remotely sensed data e.g. hyperspectral and LiDAR are becoming available for rapid and precise assessment of the forest condition. An assessment of ecological status of forest ecosystem was developed and tested using FRIM campus forest stand. The forest consisted of three major blocks; the old growth artificially regenerated native species forests, naturally regenerated forest and recent planted forest for commercial timber and other forest products. Our aim is to assess the ecological status and its proximity to the mature old growth artificially regenerated stand. We used airborne LiDAR, orthophoto and thirty field sampling quadrats of 20x20m for ground verification. The parameter assessments were grouped into four broad categories: a. forest community level-composition, structures, function; landscape structures-road network and forest edges. A metric of parameters and rating criteria was introduced as indicators of the forest ecological status. We applied multi-criteria assessment to categorize the ecological status of the forest stand. The paper demonstrates the application of the assessment approach using FRIM campus forest as its first case study. Its potential application to both artificially and naturally regenerated forest in the variety of Malaysian landscape is discussed

  1. Global Patterns of Ecosystem C Flux in Forests: a Synthesis of Biometric Measurements

    Science.gov (United States)

    Xu, B.; Fang, J.; Yang, Y.

    2012-12-01

    Assessing the carbon budget of terrestrial ecosystems is one of the key issues in current global change analyses. During the past several decades, a number of individual studies have been conducted to examine key parameters of carbon balance in forest ecosystem. These individual measurements offer the possibility to be synthesized to clarify the strength, distribution and mechanisms of carbon sequestration in world's forests. However, most previous syntheses have been derived from eddy-covariance measurements. To the best of our knowledge, key parameters of forest carbon balance obtained from biometric measurements have not yet been synthesized. In this study, we established a global dataset of forest carbon balance by collecting the data from publications which reported the biometric measurements of carbon pool and flux. This dataset contains carbon pool and flux measurements from 243 sites, 304 site/years, and 81 literatures. The main results are summarized as follows: (1) Across all sites, the average Net Ecosystem Productivity (NEP) in global forest ecosystem was 2.47 Mg C ha-1 yr-1, Net Primary Productivity (NPP) was 6.66 Mg C ha-1 yr-1, and Heterotrophic respiration (Rh) was 4.52 Mg C ha-1 yr-1. The order of NEP values was Subtropical > Temperate broadleaves > Temperate conifer > Tropical > Boreal. NPP, GPP, Rh, and Re decreased with increases in latitude. However, NEP exhibited an initial increase and then declined along the latitudinal gradient. The variation in NEP was large in the middle-latitudes. The NPP, GPP, Rh, and Re had positive relationships with mean annual temperature, and increased firstly and declined afterward with mean annual precipitation. NEP peaked in moderate climate areas. Stand age was also very important in determining forest carbon budget. The forests in middle age classes had the highest NEP, while old forests were only a small carbon sink. (2) Our results show a significant correlation between productivity and respiration in forest

  2. Recent variations in NDVI-based plant growth and their relationship with climate in boreal intact forest landscapes

    Science.gov (United States)

    Jin, J.; Jiang, H.; Lu, X.; Zhang, X.

    2015-12-01

    Intact Forest Landscapes (IFLs), defined as large unbroken expanses of forest landscape without signs of significant human activity, have significant ecological values. Previous studies suggest a reversal in the greening of boreal plants was exhibited in the late 1990s. In this study, we focus on variations in plant growth of boreal IFLs from 2000 to 2014 and their correlation with local climatic factors between 45°N and 70°N. The average Normalized Difference Vegetation Index (NDVI) during the growing season (GS, which is from April to October) derived from MOD13C2, is used as a proxy of plant growth. Compared to a significant increase in GS NDVI of boreal plants during the 1980s and early 1990s, GS NDVI of ca. 85.7% of total IFLs in the study area exhibited insignificant change after 2000. About 10.2% of total boreal IFLs exhibited significant greening (an increase in GS NDVI), and only 4.1% of the total showed significant browning (a decrease in GS NDVI) during the study period. For greening boreal IFLs, ca. 46.0% of these showed a significant correlation between GS temperature and NDVI. For browning IFLs, an increase in precipitation during the non-growing season (NGS, which is from previous November to current March) and cooling in GS and NGS were the main climatic causes for decreases of GS NDVI. However, over 65% of browning boreal IFLs did not correlate with any climatic factor, and the browning may be associated with artificial activities. About 49.4% of no-change boreal IFLs showed significant correlation between GS NDVI and climatic factors, and 72.5% of these sensitive plants exhibited a significant positive correlation between GS temperature and NDVI. On the whole, an increase in GS and NGS temperature could promote plant growth of boreal IFLs, while an increase of NGS precipitation mainly inhibited plant growth. However, nearly half of total boreal IFLs displayed no sensitivity to any climatic factors chosen in our present work.

  3. Retrieval of seasonal dynamics of forest understory reflectance from semiarid to boreal forests using MODIS BRDF data

    Science.gov (United States)

    Pisek, Jan; Chen, Jing M.; Kobayashi, Hideki; Rautiainen, Miina; Schaepman, Michael E.; Karnieli, Arnon; Sprinstin, Michael; Ryu, Youngryel; Nikopensius, Maris; Raabe, Kairi

    2016-03-01

    Spatial and temporal patterns of forest background (understory) reflectance are crucial for retrieving biophysical parameters of forest canopies (overstory) and subsequently for ecosystem modeling. In this communication, we retrieved seasonal courses of understory normalized difference vegetation index (NDVI) from multiangular Moderate Resolution Imaging Spectroradiometer bidirectional reflectance distribution function (MODIS BRDF)/albedo data. We compared satellite-based seasonal courses of understory NDVI to understory NDVI values measured in different types of forests distributed along a wide latitudinal gradient (65.12°N-31.35°N). Our results indicated that the retrieval method performs well particularly over open forests of different types. We also demonstrated the limitations of the method for closed canopies, where the understory signal retrieval is much attenuated.

  4. Analysis of litter mesofauna of Poltava region forest ecosystems

    Directory of Open Access Journals (Sweden)

    O. S. Komarov

    2007-08-01

    Full Text Available On the basis of research of litter mesofauna of 48 forest biogeocenoses the regularities of invertebrate communities formation on the species and families levels are determined. The degree of similarity of test plots are analysed by taxonomic structure of the communities. The factors of the litter invertebrate communities formation in forest ecosystems of the Poltava region are revealed.

  5. Forest Ecosystem Dynamics in a Non-Linear World

    OpenAIRE

    Haeussler, Sybille

    2009-01-01

    Forest ecosystems across North America are under increasing stress from the accelerating pace of global change which involves simultaneous changes in resource availability (temperature, moisture, nutrients), disturbance regimes (fire, insects, diseases, extreme weather, logging, urbanization) and (3) species distributions (invasive organisms, threatened species). Interactions among the agents of global change can generate emergent or unexpected ecosystem behaviour. Complex systems science pro...

  6. Ecosystem services capacity across heterogeneous forest types: understanding the interactions and suggesting pathways for sustaining multiple ecosystem services.

    Science.gov (United States)

    Alamgir, Mohammed; Turton, Stephen M; Macgregor, Colin J; Pert, Petina L

    2016-10-01

    As ecosystem services supply from tropical forests is declining due to deforestation and forest degradation, much effort is essential to sustain ecosystem services supply from tropical forested landscapes, because tropical forests provide the largest flow of multiple ecosystem services among the terrestrial ecosystems. In order to sustain multiple ecosystem services, understanding ecosystem services capacity across heterogeneous forest types and identifying certain ecosystem services that could be managed to leverage positive effects across the wider bundle of ecosystem services are required. We sampled three forest types, tropical rainforests, sclerophyll forests, and rehabilitated plantation forests, over an area of 32,000m(2) from Wet Tropics bioregion, Australia, aiming to compare supply and evaluate interactions and patterns of eight ecosystem services (global climate regulation, air quality regulation, erosion regulation, nutrient regulation, cyclone protection, habitat provision, energy provision, and timber provision). On average, multiple ecosystem services were highest in the rainforests, lowest in sclerophyll forests, and intermediate in rehabilitated plantation forests. However, a wide variation was apparent among the plots across the three forest types. Global climate regulation service had a synergistic impact on the supply of multiple ecosystem services, while nutrient regulation service was found to have a trade-off impact. Considering multiple ecosystem services, most of the rehabilitated plantation forest plots shared the same ordination space with rainforest plots in the ordination analysis, indicating that rehabilitated plantation forests may supply certain ecosystem services nearly equivalent to rainforests. Two synergy groups and one trade-off group were identified. Apart from conserving rainforests and sclerophyll forests, our findings suggest two additional integrated pathways to sustain the supply of multiple ecosystem services from a

  7. Review of nitrogen distribution and cycling in forest ecosystems

    OpenAIRE

    Harrison, A.F.; Xu, G.

    1986-01-01

    Sustained productivity of forests depends on the maintenance of soil fertility. In order to assess the long term impacts of forest management practices on soil fertility, it is not sufficient merely to examine the balances between the nutrient gains from various natural and fertilizer inputs and the losses resulting from soil leaching or tree crop removal. It is also important to understand the functioning and the rates of biological cycling within the forest ecosystem, as t...

  8. Modelling biogeochemical cycles in forest ecosystems: a Bayesian approach

    OpenAIRE

    Bagnara, Maurizio

    2015-01-01

    Forest models are tools for explaining and predicting the dynamics of forest ecosystems. They simulate forest behavior by integrating information on the underlying processes in trees, soil and atmosphere. Bayesian calibration is the application of probability theory to parameter estimation. It is a method, applicable to all models, that quantifies output uncertainty and identifies key parameters and variables. This study aims at testing the Bayesian procedure for calibration to different t...

  9. 137Cs in forest ecosystems in Estonia

    International Nuclear Information System (INIS)

    Full text: In the recently published 'Europe's Environment' (1995) one can find the map on 137Cs cumulative deposition in Europe after the Chernobyl accident (source: De Corte et al., 1990). On this map most of the Eastern Europe including Baltic Sea region is practically uncovered. In this reason we decided to present data on accumulation of 137Cs in the forest ecosystems in Estonia. Field sampling for current study has been conducted in 1986 - 1994. 137Cs concentrations were measured in different compartments of model trees, ground vegetation layers, debris and topsoil. The amount of 137Cs varied from 1.9 kBq/m2 in continental Estonia to 28.8 kBq/m2 in north-eastern Ne part of Estonia. The results obtained correspond to data presented in Wahlstroem et al., (1992) for Finland. According to the 'Europe's Environment' criteria northeastern Estonia belongs to the third cumulative deposition zone (10 to 32 kBq/m2). In Estonia the total deposition of 137Cs varies in the range from practically zero to 3.9 kBq/m2 . The calculations of Realo et al. (1994) back to May 1, 1986 gave figures from 0 to 21 kBq/m2. In macro lichens Cetraria, Cladina, Cladonia the rapid changes in 137Cs concentrations were observed: 0.06 - 0.18 kBq/kg in 1982-85, 0.93 - 6.23 kBq/kg in 1986-87, 0.27 -4.26 kBq/kg in 1988-89, 0.05 - 1.46 kBq/kg in 1990-91 and, finally, 0.03 - 0.46 kBq/kg in 1993-94. At the end of the observation period average value of the 137Cs concentrations was the same as maximum before the CRA and decline of the concentrations was 4 times during six years. Average concentrations of 137Cs in two common forest mosses Pleurozium shreberi and Hylocomium splendens was 0.43 kBq/kg of dry matter and in forest debris 0.38 kBq/kg. In 1986 the highest concentration in mushrooms - 16.6 kBq/kg was found in Lactarius sp. (Martin, L., et al., 1991). In 1991 samples of 41 different mushroom species from 63 sample sites mostly in Scots pine stands were analyzed. The highest concentration of

  10. Learning in Virtual Forest: A Forest Ecosystem in the Web-Based Learning Environment

    Science.gov (United States)

    Jussila, Terttu; Virtanen, Viivi

    2014-01-01

    Virtual Forest is a web-based, open-access learning environment about forests designed for primary-school pupils between the ages of 10 and 13 years. It is pedagogically designed to develop an understanding of ecology, to enhance conceptual development and to give a holistic view of forest ecosystems. Various learning tools, such as concept maps,…

  11. Effects of fire on major forest ecosystem processes: an overview.

    Science.gov (United States)

    Chen, Zhong

    2006-09-01

    Fire and fire ecology are among the best-studied topics in contemporary ecosystem ecology. The large body of existing literature on fire and fire ecology indicates an urgent need to synthesize the information on the pattern of fire effects on ecosystem composition, structure, and functions for application in fire and ecosystem management. Understanding fire effects and underlying principles are critical to reduce the risk of uncharacteristic wildfires and for proper use of fire as an effective management tool toward management goals. This overview is a synthesis of current knowledge on major effects of fire on fire-prone ecosystems, particularly those in the boreal and temperate regions of the North America. Four closely related ecosystem processes in vegetation dynamics, nutrient cycling, soil and belowground process and water relations were discussed with emphases on fire as the driving force. Clearly, fire can shape ecosystem composition, structure and functions by selecting fire adapted species and removing other susceptible species, releasing nutrients from the biomass and improving nutrient cycling, affecting soil properties through changing soil microbial activities and water relations, and creating heterogeneous mosaics, which in turn, can further influence fire behavior and ecological processes. Fire as a destructive force can rapidly consume large amount of biomass and cause negative impacts such as post-fire soil erosion and water runoff, and air pollution; however, as a constructive force fire is also responsible for maintaining the health and perpetuity of certain fire-dependent ecosystems. Considering the unique ecological roles of fire in mediating and regulating ecosystems, fire should be incorporated as an integral component of ecosystems and management. However, the effects of fire on an ecosystem depend on the fire regime, vegetation type, climate, physical environments, and the scale of time and space of assessment. More ecosystem

  12. Chinese Forest Ecosystem Research Network and Its Development

    Institute of Scientific and Technical Information of China (English)

    WANGBing; CUIXianghui; YANGFengwei

    2004-01-01

    Chinese Forest Ecosystem Research Network, estabfished in late 1950's and directly constructed and administered by the Science and Technology Department of State Forestry Administration of China,is a large ecology research network focuses on long-term ecosystem fixed-observation. It embodies 15 sites that represent diverse ecosystems and research priorities, including 6 state-level sites. CFERN Office coordinates communications, network publications, and research-planning activities. CFERN uses the advanced ground and spatial observation technologies such as RS, GPS, GIS to study the structure, functional laws and feedback mechanism of Chinese forest ecosystem, as well as its effects on China's social and economic development. The main tasks carried out by CFERN are: (1) construction of the database on the structure and functions of Chinese forest ecosystem and its ecological environmental factors; (2) the database construction of forest resources, ecological environment, water resources and related social economy in both regional and national scales; (3) the establishment of an evaluation system of forest ecological effects in China's main drainage areas; (4) the estabfishment of a forest environment monitoring network and a dynamic prediction and alarm system.

  13. Forest-stream linkages: effects of terrestrial invertebrate input and light on diet and growth of brown trout (Salmo trutta in a boreal forest stream.

    Directory of Open Access Journals (Sweden)

    Tibor Erős

    Full Text Available Subsidies of energy and material from the riparian zone have large impacts on recipient stream habitats. Human-induced changes, such as deforestation, may profoundly affect these pathways. However, the strength of individual factors on stream ecosystems is poorly understood since the factors involved often interact in complex ways. We isolated two of these factors, manipulating the flux of terrestrial input and the intensity of light in a 2×2 factorial design, where we followed the growth and diet of two size-classes of brown trout (Salmo trutta and the development of periphyton, grazer macroinvertebrates, terrestrial invertebrate inputs, and drift in twelve 20 m long enclosed stream reaches in a five-month-long experiment in a boreal coniferous forest stream. We found that light intensity, which was artificially increased 2.5 times above ambient levels, had an effect on grazer density, but no detectable effect on chlorophyll a biomass. We also found a seasonal effect on the amount of drift and that the reduction of terrestrial prey input, accomplished by covering enclosures with transparent plastic, had a negative impact on the amount of terrestrial invertebrates in the drift. Further, trout growth was strongly seasonal and followed the same pattern as drift biomass, and the reduction of terrestrial prey input had a negative effect on trout growth. Diet analysis was consistent with growth differences, showing that trout in open enclosures consumed relatively more terrestrial prey in summer than trout living in covered enclosures. We also predicted ontogenetic differences in the diet and growth of old and young trout, where we expected old fish to be more affected by the terrestrial prey reduction, but we found little evidence of ontogenetic differences. Overall, our results showed that reduced terrestrial prey inputs, as would be expected from forest harvesting, shaped differences in the growth and diet of the top pred