WorldWideScience

Sample records for models subalpine forest

  1. Soil Heat and Water (SHAW) Model Validation During Snowmelt in a Forested and Regenerating Clearcut on a Colorado Subalpine Hillslope

    Science.gov (United States)

    Goodbody, A.; Elder, K.; Davis, R. E.

    2003-12-01

    Perturbations to Central Rocky Mountain subalpine forests can significantly impact hydrological processes. Understanding interactions between subalpine forest and surface/subsurface hydrology at the process level is essential for the development and validation of hydrologic models. Measurements from two subalpine hillslopes are used to validate the Soil Heat and Water (SHAW) model. One hillslope is a naturally regenerating clearcut that was harvested in December 1984. Adjacently lies a second hillslope, which serves as the control and is forested with trees exceeding 80 years in age. Both plots are populated with lodgepole pine (Pinus contorta), subalpine fir (Abies lariocarpa) and Englemann spruce (Picea englemannii). Identical meteorological and hydrological measurements were made on both plots from January through June 2001. Meteorologic measurements include air temperature, relative humidity, incoming solar radiation, net radiation, wind speed and direction, soil temperature, and snow depth. Hydrologic measurements include snow water equivalent, soil moisture, snowmelt discharge at the base of the snowpack, and subsurface plot discharge. Precipitation was measured offsite in a nearby forest clearing. In addition to parameterizing the model, these measurements serve as critical validation points for model output. The model produced adequate results in both forest conditions.

  2. Warming and provenance limit tree recruitment across and beyond the elevation range of subalpine forest

    Science.gov (United States)

    Kueppers, Lara M.; Conlisk, Erin; Castanha, Cristina; Moyes, Andrew B.; Germino, Matthew; de Valpine, Perry; Torn, Margaret S.; Mitton, Jeffry B.

    2017-01-01

    Climate niche models project that subalpine forest ranges will extend upslope with climate warming. These projections assume that the climate suitable for adult trees will be adequate for forest regeneration, ignoring climate requirements for seedling recruitment, a potential demographic bottleneck. Moreover, local genetic adaptation is expected to facilitate range expansion, with tree populations at the upper forest edge providing the seed best adapted to the alpine. Here, we test these expectations using a novel combination of common gardens, seeded with two widely distributed subalpine conifers, and climate manipulations replicated at three elevations. Infrared heaters raised temperatures in heated plots, but raised temperatures more in the forest than at or above treeline because strong winds at high elevation reduced heating efficiency. Watering increased season-average soil moisture similarly across sites. Contrary to expectations, warming reduced Engelmann spruce recruitment at and above treeline, as well as in the forest. Warming reduced limber pine first-year recruitment in the forest, but had no net effect on fourth-year recruitment at any site. Watering during the snow-free season alleviated some negative effects of warming, indicating that warming exacerbated water limitations. Contrary to expectations of local adaptation, low-elevation seeds of both species initially recruited more strongly than high-elevation seeds across the elevation gradient, although the low-provenance advantage diminished by the fourth year for Engelmann spruce, likely due to small sample sizes. High- and low-elevation provenances responded similarly to warming across sites for Engelmann spruce, but differently for limber pine. In the context of increasing tree mortality, lower recruitment at all elevations with warming, combined with lower quality, high-provenance seed being most available for colonizing the alpine, portends range contraction for Engelmann spruce. The lower

  3. Hydrological Features on Subalpine Forest Zone in the East of Qinghai-Tibet Plateau

    Science.gov (United States)

    Zhong, X.; Cheng, G.; Guo, W.

    2008-12-01

    The Hengduan mountain chains of China is situated on the east of Qinghai-Tibet Plateau with area of more than 400,000 km2. Mountains and rivers run through in north-south direction, and are collocated side by side on east-west. Elevation difference between ridges and valleys has great disparity, normally of 1000-2500m, so the vertical zones of vegetation are very distinct. Subalpine coniferous forest zone, mainly composed of fir (Abies) and spruce (Picea), is on altitude of 2800-4200m, which is a chief component of the forested area in southwest China, and an important region for water conservation of several international rivers inlcuding Nujiang River and Lancangjiang River, as well as the world-famous Changjiang River. Thus, it has both theoretical and practical significance to study hydrological process and laws of forest in this region. The study area is located at the Gongga Mountain, on the east edge of the Hengduan mountain chains. Elevation of the main peak is 7556m, and elevation difference between ridge and valley on the eastern slope is 6400m. An ecological observation station was built at altitude of 3000m on the eastern slope of Gongga Mountain in 1988, mainly for alpine ecology and forest hydrology research. Based on the analysis of 20- years observation data from this station, it is revealed that hydrological process of forest in this area has several features as follows: (1) Canopy interception of primitive fir (Abies) forest is obviously greater than other tree species, and interception rate is 30-40%. Maximal canopy interception of one-time precipitation of primitive fir forest is commonly 2-5mm. According to observation data of canopy interception, a conceptual model of canopy interception of fir forest is established: R=1.69[(1-exp(-0.41P))+0.19P (P is precipitation in mm); (2) Natural valid moisture holding capacity in layer of moss-decayed wood and leaves beneath trees is up to 5.6mm. Porosity in soil surface layer and non-capillary porosity

  4. Comparison of the abundance and composition of litter fauna in tropical and subalpine forests

    Science.gov (United States)

    G. Gonzalez; T.R. Seastedt

    2000-01-01

    In this study, we quantify the abundance and composition of the litter fauna in dry and wet tropical forests and north- and south-facing subalpine forests. We used the same litter species contained in litterbags across study sites to standardize for substrate conditions, and a single method of fauna extraction from the litter (Tullgren method). Fauna densities were...

  5. Bleaching of leaf litter and associated microfungi in subboreal and subalpine forests.

    Science.gov (United States)

    Hagiwara, Yusuke; Matsuoka, Shunsuke; Hobara, Satoru; Mori, Akira S; Hirose, Dai; Osono, Takashi

    2015-10-01

    Fungal decomposition of lignin leads to the whitening, or bleaching, of leaf litter, especially in temperate and tropical forests, but less is known about such bleaching in forests of cooler regions, such as boreal and subalpine forests. The purposes of the present study were to examine the extent of bleached area on the surface of leaf litter and its variation with environmental conditions in subboreal and subalpine forests in Japan and to examine the microfungi associated with the bleaching of leaf litter by isolating fungi from the bleached portions of the litter. Bleached area accounted for 21.7%-32.7% and 2.0%-10.0% of total leaf area of Quercus crispula and Betula ermanii, respectively, in subboreal forests, and for 6.3% and 18.6% of total leaf area of B. ermanii and Picea jezoensis var. hondoensis, respectively, in a subalpine forest. In subboreal forests, elevation, C/N ratio and pH of the FH layer, and slope aspect were selected as predictor variables for the bleached leaf area. Leaf mass per area and lignin content were consistently lower in the bleached area than in the nonbleached area of the same leaves, indicating that the selective decomposition of acid unhydrolyzable residue (recalcitrant compounds such as lignin, tannins, and cutins) enhanced the mass loss of leaf tissues in the bleached portions. Isolates of a total of 11 fungal species (6 species of Ascomycota and 5 of Basidiomycota) exhibited leaf-litter-bleaching activity under pure culture conditions. Two fungal species (Coccomyces sp. and Mycena sp.) occurred in both subboreal and subalpine forests, which were separated from each other by approximately 1100 km.

  6. Energy Budget of A Subalpine Forest Measured By A Suspended Bowen-ratio System

    Science.gov (United States)

    Eugster, Werner; Cattin, René

    Energy budget measurements performed during the BOREAS project in North Amer- ica revealed that evapotranspiration from boreal coniferous forests were significantly below the rates previously assumed by regional climate and weather forecast mod- els. Since the subalpine forests in the Alps and other mountain regions of the world are believed to be the corresponding ecosystem type within an altitudinal gradient we attempted to measure the energy budget of a subalpine spruce (Picea abies) forest in comparison with a nearby meadow at an elevation of 1400 m in the Swiss Alps. For the measurements over the forest a new concept was tested to use a suspended Bowen-ratio system that was attached to a cable crossing a gully to be placed over a 10-year old tree canopy. This installation was developed because of the geological conditions at the research site which did not allow the construction of a solid tower (apart from the costs that such a tower would cost) in this torrent catchment that be- longs to the Natural Hazard Investigation Area of the University of Bern. The setup over the meadow was a standard setup attached to a 5 m tower. This paper addresses the experience gained with the two setups. The results from this comparison indicate that due to the difference in topographical conditions (a north- facing slope compared to the relatively flat BOREAS landscapes) the conditions found during BOREAS cannot be translated to coniferous forests in such subalpine areas of the Alps. Our measurements suggest that the energy budget of the selected forest type is similar to an oasis condition and should be regarded as a gully forest effect with a significant contribution of downward sensible heat flux to provide energy for evapotranspiration of the forest.

  7. Soil seed banks along elevational gradients in tropical, subtropical and subalpine forests in Yunnan Province, southwest China

    Directory of Open Access Journals (Sweden)

    Xiaqin Luo

    2017-10-01

    Full Text Available Soil seed banks are a vital part of ecosystems and influence community dynamics and regeneration. Although soil seed banks in different habitats have been reported, how soil seed banks vary with elevational gradients in different climatic zones is still unknown. This paper investigates seed density, species composition and nonconstituent species of forest soil seed banks in Yunnan Province, southwest China. Similarity between the soil seed bank and standing vegetation was also examined. We collected soil samples from sites spanning 12 elevations in tropical rain forests, subtropical evergreen broad-leaved forests and subalpine coniferous forests, and transported them to a glasshouse for germination trials for species identification. The soil seed banks of tropical and subtropical forests had much higher seed densities and species richness than those of subalpine forests. Seeds of woody species dominated the soil seed banks of tropical and subtropical forests, while herbs dominated those of subalpine forests. The nonconstituent species in the soil seed banks were all herbs and were most abundant in tropical forests, followed by subtropical forests but were completely absent from subalpine forests.

  8. Use of passive UAS imaging to measure biophysical parameters in a southern Rocky Mountain subalpine forest

    Science.gov (United States)

    Caldwell, M. K.; Sloan, J.; Mladinich, C. S.; Wessman, C. A.

    2013-12-01

    Unmanned Aerial Systems (UAS) can provide detailed, fine spatial resolution imagery for ecological uses not otherwise obtainable through standard methods. The use of UAS imagery for ecology is a rapidly -evolving field, where the study of forest landscape ecology can be augmented using UAS imagery to scale and validate biophysical data from field measurements to spaceborne observations. High resolution imagery provided by UAS (30 cm2 pixels) offers detailed canopy cover and forest structure data in a time efficient and inexpensive manner. Using a GoPro Hero2 (2 mm focal length) camera mounted in the nose cone of a Raven unmanned system, we collected aerial and thermal data monthly during the summer 2013, over two subalpine forests in the Southern Rocky Mountains in Colorado. These forests are dominated by lodgepole pine (Pinus ponderosae) and have experienced insect-driven (primarily mountain pine beetle; MPB, Dendroctonus ponderosae) mortality. Objectives of this study include observations of forest health variables such as canopy water content (CWC) from thermal imagery and leaf area index (LAI), biomass and forest productivity from the Normalized Difference Vegetation Index (NDVI) from UAS imagery. Observations were, validated with ground measurements. Images were processed using a combination of AgiSoft Photoscan professional software and ENVI remote imaging software. We utilized the software Leaf Area Index Calculator (LAIC) developed by Córcoles et al. (2013) for calculating LAI from digital images and modified to conform to leaf area of needle-leaf trees as in Chen and Cihlar (1996) . LAIC uses a K-means cluster analysis to decipher the RGB levels for each pixel and distinguish between green aboveground vegetation and other materials, and project leaf area per unit of ground surface area (i.e. half total needle surface area per unit area). Preliminary LAIC UAS data shows summer average LAI was 3.8 in the most dense forest stands and 2.95 in less dense

  9. Ecological processes dominate the 13C land disequilibrium in a Rocky Mountain subalpine forest

    Science.gov (United States)

    Bowling, D. R.; Ballantyne, A. P.; Miller, J. B.; Burns, S. P.; Conway, T. J.; Menzer, O.; Stephens, B. B.; Vaughn, B. H.

    2014-04-01

    Fossil fuel combustion has increased atmospheric CO2 by ≈ 115 µmol mol-1 since 1750 and decreased its carbon isotope composition (δ13C) by 1.7-2‰ (the 13C Suess effect). Because carbon is stored in the terrestrial biosphere for decades and longer, the δ13C of CO2 released by terrestrial ecosystems is expected to differ from the δ13C of CO2 assimilated by land plants during photosynthesis. This isotopic difference between land-atmosphere respiration (δR) and photosynthetic assimilation (δA) fluxes gives rise to the 13C land disequilibrium (D). Contemporary understanding suggests that over annual and longer time scales, D is determined primarily by the Suess effect, and thus, D is generally positive (δR > δA). A 7 year record of biosphere-atmosphere carbon exchange was used to evaluate the seasonality of δA and δR, and the 13C land disequilibrium, in a subalpine conifer forest. A novel isotopic mixing model was employed to determine the δ13C of net land-atmosphere exchange during day and night and combined with tower-based flux observations to assess δA and δR. The disequilibrium varied seasonally and when flux-weighted was opposite in sign than expected from the Suess effect (D = -0.75 ± 0.21‰ or -0.88 ± 0.10‰ depending on method). Seasonality in D appeared to be driven by photosynthetic discrimination (Δcanopy) responding to environmental factors. Possible explanations for negative D include (1) changes in Δcanopy over decades as CO2 and temperature have risen, and/or (2) post-photosynthetic fractionation processes leading to sequestration of isotopically enriched carbon in long-lived pools like wood and soil.

  10. Root hydraulic vulnerability regulation of whole-plant conductance along hillslope gradients within subalpine and montane forests

    Science.gov (United States)

    Beverly, D.; Speckman, H. N.; Ewers, B. E.

    2017-12-01

    Ecosystem-scale models often rely on root vulnerability or whole-plant conductance for simulating seasonal evapotranspiration declines via constraints of water uptake and vegetation mortality. Further, many of these ecosystem models rely on single, unvarying, hydraulic parameter estimates for modeling large areas. Ring-porous species have shown seasonal variability in root vulnerability (percent loss of conductivity; PLC) and whole-plant conductance (Kw) but simulations of coniferous forest typically rely on point measurements. This assumption for coniferous forest is not likely true because of seasonal variability caused by phenology and environmental stresses and the potential for cavitation fatigue is not considered. Moreover, many of these dynamics have only been considered for stems even though roots are often the most vulnerable segments of the pathway for conifers. We hypothesized that seasonally dynamic whole-plant conductance along hillslope gradients in coniferous forests are regulated by cavitation fatigue within the roots resulting in seasonal increases in vulnerability. To test the hypothesis, a subalpine mixed forest (3000 m.a.s.l) and montane forest (2550 m.a.s.l.) were monitored between 2015-2017 to quantify PLC and Kw along the hillslope gradients of 300 m and 50 m, respectively. Forest plots were instrumented with 35 Granier-type sapflow sensors. Seasonal sampling campaigns occurred to quantify PLC through centrifuge techniques and Kw through Darcy's law approximations with pre-dawn and diurnal leaf water potentials. Downslope roots exhibit a 33% decrease in maximal conductivity corresponding to the approximately 50% decrease in whole-plant conductance suggesting seasonal soil dry-down limitations within the downslope stands. Upslope stands had no to little change in root vulnerability or decrease in whole-plant conductance as soil water limitations occur immediately following snowmelt, thus limiting hydraulic conductance throughout the growing

  11. Long-term landscape changes in a subalpine spruce-fir forest in central Utah, USA

    Directory of Open Access Journals (Sweden)

    Jesse L. Morris1

    2015-12-01

    Full Text Available Background: In Western North America, increasing wildfire and outbreaks of native bark beetles have been mediated by warming climate conditions. Bioclimatic models forecast the loss of key high elevation species throughout the region. This study uses retrospective vegetation and fire history data to reconstruct the drivers of past disturbance and environmental change. Understanding the relationship among climate, antecedent disturbances, and the legacy effects of settlement-era logging can help identify the patterns and processes that create landscapes susceptible to bark beetle epidemics. Methods: Our analysis uses data from lake sediment cores, stand inventories, and historical records. Sediment cores were dated with radiometric techniques (14C and 210Pb/137Cs and subsampled for pollen and charcoal to maximize the temporal resolution during the historical period (1800 CE to present and to provide environmental baseline data (last 10,500 years. Pollen data for spruce were calibrated to carbon biomass (C t/ha using standard allometric equations and a transfer function. Charcoal samples were analyzed with statistical models to facilitate peak detection and determine fire recurrence intervals. Results: The Wasatch Plateau has been dominated by Engelmann spruce forests for the last ~10,500 years, with subalpine fir becoming more prominent since 6000 years ago. This landscape has experienced a dynamic fire regime, where burning events are more frequent and of higher magnitude during the last 3000 years. Two important disturbances have impacted Engelmann spruce in the historical period: 1 high-grade logging during the late 19th century; and (2 a high severity spruce beetle outbreak in the late 20th century that killed >90 % of mature spruce (>10 cm dbh. Conclusions: Our study shows that spruce-dominated forests in this region are resilient to a range of climate and disturbance regimes. Several lines of evidence suggest that 19th century logging

  12. Extensive wildfires, climate change, and an abrupt state change in subalpine ribbon forests, Colorado.

    Science.gov (United States)

    Calder, W John; Shuman, Bryan

    2017-10-01

    Ecosystems may shift abruptly when the effects of climate change and disturbance interact, and landscapes with regularly patterned vegetation may be especially vulnerable to abrupt shifts. Here we use a fossil pollen record from a regularly patterned ribbon forest (alternating bands of forests and meadows) in Colorado to examine whether past changes in wildfire and climate produced abrupt vegetation shifts. Comparing the percentages of conifer pollen with sedimentary δ 18 O data (interpreted as an indicator of temperature or snow accumulation) indicates a first-order linear relationship between vegetation composition and climate change with no detectable lags over the past 2,500 yr (r = 0.55, P wildfires, which were recognized in a previous study to have burned approximately 80% of the surrounding 1,000 km 2 landscape 1,000 yr ago when temperatures rose ~0.5°C. The vegetation change was larger than expected from the effects of climate change alone. Pollen assemblages changed from a composition associated with closed subalpine forests to one similar to modern ribbon forests. Fossil pollen assemblages then remained like those from modern ribbon forests for the following ~1,000 yr, providing a clear example of how extensive disturbances can trigger persistent new vegetation states and alter how vegetation responds to climate. © 2017 by the Ecological Society of America.

  13. Human disturbance provides foraging opportunities for birds in primary subalpine forest

    DEFF Research Database (Denmark)

    DuBay, Shane G.; Hart Reeve, Andrew; Wu, Yongjie

    2017-01-01

    or Cettia major, and Heteroxenicus stellatus. This behavior is likely a modification of pre-existing interspecific foraging associations with pheasants and large mammals in the region. These larger animals disturb the earth and lower vegetation layers upon passage and while foraging, exposing previously......Interspecific foraging associations are well-documented phenomena, characterized by one or more species exploiting the behavior of another species to decrease predation or increase foraging success. In rare cases, birds directly exploit human behavior, but examples of these interactions are limited...... to species that naturally occur in edge, open, or disturbed habitats. With observations and experiments we provide evidence of insectivorous birds exploiting human disturbance in primary subalpine forest in the mountains of southern China, displaying behavioral flexibility to gain novel foraging...

  14. Litter Production, Decomposition, and Nutrient Release in Subalpine Forest Communities of the Northwest Himalaya

    Directory of Open Access Journals (Sweden)

    Vinod K. Bisht

    2014-01-01

    Full Text Available Production, decomposition, and release of nutrients from leaf and nonleaf litter were investigated in four subalpine forests of North-West Himalaya, India. Total annual litter fall in four communities varied from 2950.00 to 4040.00 kg ha−1 and was found significant (CD0.05 = 118.2. Decomposition of leaf litter varied from 1.82–3.5% during autumn-winter to 36.14–45.51 during summer rainy season in all stands and percent of mass loss was significantly varied in stands (CD6.00. Similarly, decomposition in nonleaf litter was varied from 0.3–1.1% during autumn-winter to 19.59–30.05% during summer rainy season and was significantly varied irrespective of seasons. However, percent decomposition of leaf litter and the values of decay constant (k were at par in all stands. Total standing state of nutrients in fresh litter as well as release of total nitrogen (N, phosphorus (P, and potassium (K in due course of decomposition (12 months was also varying significantly. The rate of nonleaf litter decomposition was significantly positively correlated with air temperature (r=0.63–0.74 in all communities. The significant correlation (r=0.85 was observed only in Rhododendron-Sorbus forest community (PRS. Study indicates that the air temperature is a major determinant for nonleaf litter decomposition in this region.

  15. Stand structure, recruitment and growth dynamics in mixed subalpine spruce and Swiss stone pine forests in the Eastern Carpathians.

    Science.gov (United States)

    Popa, Ionel; Nechita, Constantin; Hofgaard, Annika

    2017-11-15

    Natural subalpine forests are considered to be sensitive to climate change, and forest characteristics are assumed to reflect the prevalent disturbance regime. We hypothesize that stand history determines different stand structures. Based on large full inventory datasets (including tree biometric data, spatial coordinates, tree age, and basal area increment) we assessed the size structure, tree recruitment dynamics and radial growth patterns in three permanent plots along an altitudinal gradient in a mixed coniferous forest (Picea abies and Pinus cembra) in the Eastern Carpathians. Both discrete disturbances (large scale or small scale) and chronic disturbances (climate change) were identified as drivers of stand structure development in the studied plots. A stand replacing wind disturbance generated a unimodal bell-shaped size and age distribution for both species characterized by a sharp increase in post-disturbance recruitment. By contrast, small-scale wind-caused gaps led to a negative exponential diameter distribution for spruce and a left-asymmetric unimodal for pine. Climate-driven infilling processes in the upper subalpine forest were reflected as J-shaped size and age distributions for both species, but with pine predating spruce. The growth patterns for both species demonstrated an increased basal area increment since the early 1900s, with an emphasis in the last few decades, irrespective of stand history. Pine demonstrated a competitive advantage compared to spruce due to the higher growth rate and size at the same age. Recognition of combined discrete and chronic disturbances as drivers of the tree layer characteristics in a subalpine coniferous forest is essential in both stand history analyses and growth predictions. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Total belowground carbon flux in subalpine forests is related to leaf area index, soil nitrogen, and tree height

    Science.gov (United States)

    Berryman, Erin Michele; Ryan, Michael G.; Bradford, John B.; Hawbaker, Todd J.; Birdsey, R.

    2016-01-01

    In forests, total belowground carbon (C) flux (TBCF) is a large component of the C budget and represents a critical pathway for delivery of plant C to soil. Reducing uncertainty around regional estimates of forest C cycling may be aided by incorporating knowledge of controls over soil respiration and TBCF. Photosynthesis, and presumably TBCF, declines with advancing tree size and age, and photosynthesis increases yet C partitioning to TBCF decreases in response to high soil fertility. We hypothesized that these causal relationships would result in predictable patterns of TBCF, and partitioning of C to TBCF, with natural variability in leaf area index (LAI), soil nitrogen (N), and tree height in subalpine forests in the Rocky Mountains, USA. Using three consecutive years of soil respiration data collected from 22 0.38-ha locations across three 1-km2 subalpine forested landscapes, we tested three hypotheses: (1) annual soil respiration and TBCF will show a hump-shaped relationship with LAI; (2) variability in TBCF unexplained by LAI will be related to soil nitrogen (N); and (3) partitioning of C to TBCF (relative to woody growth) will decline with increasing soil N and tree height. We found partial support for Hypothesis 1 and full support for Hypotheses 2 and 3. TBCF, but not soil respiration, was explained by LAI and soil N patterns (r2 = 0.49), and the ratio of annual TBCF to TBCF plus aboveground net primary productivity (ANPP) was related to soil N and tree height (r2 = 0.72). Thus, forest C partitioning to TBCF can vary even within the same forest type and region, and approaches that assume a constant fraction of TBCF relative to ANPP may be missing some of this variability. These relationships can aid with estimates of forest soil respiration and TBCF across landscapes, using spatially explicit forest data such as national inventories or remotely sensed data products.

  17. The 'plant economic spectrum' in bryophytes, a comparative study in subalpine forest.

    Science.gov (United States)

    Wang, Zhe; Liu, Xin; Bader, Maaike Y; Feng, Defeng; Bao, Weikai

    2017-02-01

    Tradeoffs among functional traits of vascular plants are starting to be better understood, but it is unclear whether bryophytes possess similar tradeoffs or how trait relationships, or the 'economic spectrum', differ between the two groups. We determined functional-trait values [including shoot mass per area (SMA), light-saturated assimilation rate (A mass ), dark respiration rate (Rd mass ), N and P concentrations (N mass and P mass ), and photosynthetic N and P use efficiency (PNUE and PPUE)] and their bivariate relationships for 28 bryophytes growing in a subalpine old-growth fir forest on the eastern Tibetan Plateau. Trait values and scaling relationships of these bryophytes were compared with data for vascular plant leaves from the Global Plant Trait Network (GLOPNET) dataset. We found that the A mass , N mass , N:P, PNUE and PPUE of bryophyte shoots were lower than those of vascular plant leaves. In contrast, bryophytes possessed higher P mass and the two groups had similar values of SMA and Rd mass . The N mass and P mass were closely associated with A mass and Rd mass , and these traits were all significantly negatively related to SMA. Metabolic rates increased faster with nutrient concentrations in bryophytes than in vascular plants. Our research indicates that bryophytes have similar trait relationships as vascular plant leaves, although the slopes of the relationships differ for most trait combinations. This study confirms a functional-trait tradeoff in bryophytes, and reveals that bryophytes allocate greater proportions of N and P into the metabolic pools. © 2017 Botanical Society of America.

  18. Long-term reactive nitrogen loading alters soil carbon and microbial community properties in a subalpine forest ecosystem

    Science.gov (United States)

    Boot, Claudia M.; Hall, Ed K.; Denef, Karolien; Baron, Jill S.

    2016-01-01

    Elevated nitrogen (N) deposition due to increased fossil fuel combustion and agricultural practices has altered global carbon (C) cycling. Additions of reactive N to N-limited environments are typically accompanied by increases in plant biomass. Soil C dynamics, however, have shown a range of different responses to the addition of reactive N that seem to be ecosystem dependent. We evaluated the effect of N amendments on biogeochemical characteristics and microbial responses of subalpine forest organic soils in order to develop a mechanistic understanding of how soils are affected by N amendments in subalpine ecosystems. We measured a suite of responses across three years (2011–2013) during two seasons (spring and fall). Following 17 years of N amendments, fertilized soils were more acidic (control mean 5.09, fertilized mean 4.68), and had lower %C (control mean 33.7% C, fertilized mean 29.8% C) and microbial biomass C by 22% relative to control plots. Shifts in biogeochemical properties in fertilized plots were associated with an altered microbial community driven by reduced arbuscular mycorrhizal (control mean 3.2 mol%, fertilized mean 2.5 mol%) and saprotrophic fungal groups (control mean 17.0 mol%, fertilized mean 15.2 mol%), as well as a decrease in N degrading microbial enzyme activity. Our results suggest that decreases in soil C in subalpine forests were in part driven by increased microbial degradation of soil organic matter and reduced inputs to soil organic matter in the form of microbial biomass.

  19. Resistance of mixed subalpine forest to fire frequency changes: the ecological function of dwarf pine (Pinus mugo ssp. mugo)

    Science.gov (United States)

    Leys, Bérangère; Carcaillet, Christopher; Blarquez, Olivier; Lami, Andrea; Musazzi, Simona; Trevisan, Renata

    2014-04-01

    The availability of fuel and climate are major factors responsible for forest fire activity over time. Here, we tested the hypothesis that forest ecosystems containing a high shrub biomass, which constitutes a fuel load, and affected by a warmer climate, which is associated with drier conditions and a longer fire season, are more prone to fire. Fire occurrence and woody vegetation histories were reconstructed for a subalpine site (Lago di Colbricon Inferiore) in the Dolomites, part of the eastern Italian Alps, for the past 13,000 years. The modern wet climate prevents fire in this area, in spite of the warm summers and an abundant biomass of dwarf pine (Pinus mugo) and three other conifer tree species (Pinus cembra, Picea abies, and Larix decidua). Past fire history reconstructed from sedimentary charcoal showed a median fire return interval of 140 years (30-735 yr fire-1), with a high variability (SD ± 170 years) throughout the Holocene, suggesting that the past environment was more favourable to fire than the modern one, probably due to a drier climate or to different fuel availability. The subalpine community containing P. mugo remained stable for the past 9000 years, despite the variability of the fire return interval. Interestingly, the fire frequency is higher at Lago di Colbricon than at sites in the western Alps that lack P. mugo, suggesting that this species tolerates fire disturbance. In fact, it probably favours the spread of fire due to its flammable biomass, prostrated form, and dense layering canopy, thus offsetting the influence of the wet climate. Since the 19th century, the removal of dwarf pine to promote subalpine grasslands may have suppressed fires in this region.

  20. Water use patterns of three species in subalpine forest, Southwest China: the deuterium isotope approach

    Science.gov (United States)

    Qing Xu; Harbin Li; Jiquan Chen; Jiquan Cheng; Xiaoli Cheng; Shirong Liu; Shuqing An

    2011-01-01

    Determination of water sources of plant species in a community is critical for understanding the hydrological processes and their importance in ecosystem functions. Such partitioning of plant xylem water into specific sources (i.e. precipitation, groundwater) can be achieved by analyzing deuterium isotopic composition (δD) values for source waters. A subalpine dark...

  1. The future of subalpine forests in the Southern Rocky Mountains: Trajectories for Pinus aristata genetic lineages

    Science.gov (United States)

    Sparkle L. Malone; Anna W. Schoettle; Jonathan D. Coop

    2018-01-01

    Like many other high elevation alpine tree species, Rocky Mountain bristlecone pine (Pinus aristata Engelm.) may be particularly vulnerable to climate change. To evaluate its potential vulnerability to shifts in climate, we defined the suitable climate space for each of four genetic lineages of bristlecone pine and for other subalpine tree species in close proximity to...

  2. Charcoal and Total Carbon in Soils from Foothills Shrublands to Subalpine Forests in the Colorado Front Range

    Directory of Open Access Journals (Sweden)

    Robert Sanford

    2012-10-01

    Full Text Available Temperate conifer forests in the Colorado Front Range are fire-adapted ecosystems where wildland fires leave a legacy in the form of char and charcoal. Long-term soil charcoal C (CC pools result from the combined effects of wildland fires, aboveground biomass characteristics and soil transfer mechanisms. We measured CC pools in surface soils (0–10 cm at mid-slope positions on east facing aspects in five continuous foothills shrubland and conifer forest types. We found a significant statistical effect of vegetation type on CC pools along this ecological gradient, but not a linear pattern increasing with elevation gain. There is a weak bimodal pattern of CC gain with elevation between foothills shrublands (1.2 mg CC ha−1 and the lower montane, ponderosa pine (1.5 mg CC ha−1 and Douglas-fir (1.5 mg CC ha−1 forest types prior to a mid-elevation decline in upper montane lodgepole pine forests (1.2 mg CC ha−1 before increasing again in the spruce/subalpine fir forests (1.5 mg CC ha−1. We propose that CC forms and accumulates via unique ecological conditions such as fire regime. The range of soil CC amounts and ratios of CC to total SOC are comparable to but lower than other regional estimates.

  3. Complex terrain alters temperature and moisture limitations of forest soil respiration across a semiarid to subalpine gradient

    Science.gov (United States)

    Berryman, Erin Michele; Barnard, H.R.; Adams, H.R.; Burns, M.A.; Gallo, E.; Brooks, P.D.

    2015-01-01

    Forest soil respiration is a major carbon (C) flux that is characterized by significant variability in space and time. We quantified growing season soil respiration during both a drought year and a nondrought year across a complex landscape to identify how landscape and climate interact to control soil respiration. We asked the following questions: (1) How does soil respiration vary across the catchments due to terrain-induced variability in moisture availability and temperature? (2) Does the relative importance of moisture versus temperature limitation of respiration vary across space and time? And (3) what terrain elements are important for dictating the pattern of soil respiration and its controls? Moisture superseded temperature in explaining watershed respiration patterns, with wetter yet cooler areas higher up and on north facing slopes yielding greater soil respiration than lower and south facing areas. Wetter subalpine forests had reduced moisture limitation in favor of greater seasonal temperature limitation, and the reverse was true for low-elevation semiarid forests. Coincident climate poorly predicted soil respiration in the montane transition zone; however, antecedent precipitation from the prior 10 days provided additional explanatory power. A seasonal trend in respiration remained after accounting for microclimate effects, suggesting that local climate alone may not adequately predict seasonal variability in soil respiration in montane forests. Soil respiration climate controls were more strongly related to topography during the drought year highlighting the importance of landscape complexity in ecosystem response to drought.

  4. Tree age, disturbance history, and carbon stocks and fluxes in subalpine Rocky Mountain forests

    Science.gov (United States)

    J.B. Bradford; R.A. Birdsey; L.A. Joyce; M.G. Ryan

    2008-01-01

    Forest carbon stocks and fluxes vary with forest age, and relationships with forest age are often used to estimate fluxes for regional or national carbon inventories. Two methods are commonly used to estimate forest age: observed tree age or time since a known disturbance. To clarify the relationships between tree age, time since disturbance and forest carbon storage...

  5. Simulating Canopy-Level Solar Induced Fluorescence with CLM-SIF 4.5 at a Sub-Alpine Conifer Forest in the Colorado Rockies

    Science.gov (United States)

    Raczka, B. M.; Bowling, D. R.; Lin, J. C.; Lee, J. E.; Yang, X.; Duarte, H.; Zuromski, L.

    2017-12-01

    Forests of the Western United States are prone to drought, temperature extremes, forest fires and insect infestation. These disturbance render carbon stocks and land-atmosphere carbon exchanges highly variable and vulnerable to change. Regional estimates of carbon exchange from terrestrial ecosystem models are challenged, in part, by a lack of net ecosystem exchange observations (e.g. flux towers) due to the complex mountainous terrain. Alternatively, carbon estimates based on light use efficiency models that depend upon remotely-sensed greenness indices are challenged due to a weak relationship with GPP during the winter season. Recent advances in the retrieval of remotely sensed solar induced fluorescence (SIF) have demonstrated a strong seasonal relationship between GPP and SIF for deciduous, grass and, to a lesser extent, conifer species. This provides an important opportunity to use remotely-sensed SIF to calibrate terrestrial ecosystem models providing a more accurate regional representation of biomass and carbon exchange across mountainous terrain. Here we incorporate both leaf-level fluorescence and leaf-to-canopy radiative transfer represented by the SCOPE model into CLM 4.5 (CLM-SIF). We simulate canopy level fluorescence at a sub-alpine forest site (Niwot Ridge, Colorado) and test whether these simulations reproduce remotely-sensed SIF from a satellite (GOME2). We found that the average peak SIF during the growing season (yrs 2007-2013) was similar between the model and satellite observations (within 15%); however, simulated SIF during the winter season was significantly greater than the satellite observations (5x higher). This implies that the fluorescence yield is overestimated by the model during the winter season. It is important that the modeled representation of seasonal fluorescence yield is improved to provide an accurate seasonal representation of SIF across the Western United States.

  6. Subalpine Pyrenees received higher nitrogen deposition than predicted by EMEP and CHIMERE chemistry-transport models

    Science.gov (United States)

    Boutin, Marion; Lamaze, Thierry; Couvidat, Florian; Pornon, André

    2015-08-01

    Deposition of reactive nitrogen (N) from the atmosphere is expected to be the third greatest driver of biodiversity loss by the year 2100. Chemistry-transport models are essential tools to estimate spatially explicit N deposition but the reliability of their predictions remained to be validated in mountains. We measured N deposition and air concentration over the subalpine Pyrenees. N deposition was found to range from 797 to 1,463 mg N m-2 year-1. These values were higher than expected from model predictions, especially for nitrate, which exceeded the estimations of EMEP by a factor of 2.6 and CHIMERE by 3.6. Our observations also displayed a reversed reduced-to-oxidized ratio in N deposition compared with model predictions. The results highlight that the subalpine Pyrenees are exposed to higher levels of N deposition than expected according to standard predictions and that these levels exceed currently recognized critical loads for most high-elevation habitats. Our study reveals a need to improve the evaluation of N deposition in mountains which are home to a substantial and original part of the world’s biodiversity.

  7. Natural Terrestrial Sequestration Potential of Highplains Prairie to Subalpine Forest and Mined-Lands Soils Derived from Weathering of Tertiary Volcanics

    Science.gov (United States)

    Yager, D. B.; Burchell, A.; Robinson, R.; Odell, S.; Dick, R. P.; Johnson, C. A.; Hidinger, J.; Rathke, D.

    2007-12-01

    There is now widespread agreement that, if the climate is to be stabilized, then net greenhouse gas emissions must be greatly reduced (IPCC, 2007). The need to reduce net CO2 emissions plus the possible economic and environmental ramifications of not addressing climate change have stimulated important atmospheric carbon mitigation actions, as well as, studies to understand and quantify potential carbon sinks. Soils represent a potentially large and environmentally significant natural carbon reservoir. Increasing the natural terrestrial sequestration potential (NTS) of soils is among the seven, "Sokolow CO2 stabilization wedges' or carbon management strategies needed to thwart doubling of atmospheric CO2. Additionally, high plains to subalpine temperate soils tend to be less susceptible to baseline C pool declines due to global warming than are warmer regions and are important ecosystems in which to quantify soil carbon storage capacity. To examine the potential of magnesium silicate-bearing soils to sequester additional carbon, we sampled 60 high plains prairie to subalpine forest soil horizons derived from weathering of Tertiary-age dacite-andesite- basalt compositions in Colorado, U.S.A.: the San Luis Valley, San Juan Volcanic Field, Grand Mesa, White River- Roan Plateau (Flat Tops), Rocky Mountain National Park, Front Range and propylitically-altered terrain in the western San Juan Volcanic field containing secondary magnesium silicates (chlorite-species). Data for C, N, O (total conc., isotopes), metals, major and trace elements, Hg, S, microbial enzymes (β-glucosidase, arylsulfatase, acid neutralizing capacity (ANC), and 14C radiocarbon dates are reported. Samples demonstrate variable but elevated C relative to average global soil C. In particular, the propylitically-altered rocks have a high instantaneous ANC in laboratory tests (> 20 kg/ton CaCO3 equivalent) and derivative forest soils containing low-temperature charcoal "burn" horizons have high total

  8. Fine-scale distribution of ectomycorrhizal fungi colonizing Tsuga diversifolia seedlings growing on rocks in a subalpine Abies veitchii forest.

    Science.gov (United States)

    Yoshida, Naohiro; Son, Joung A; Matsushita, Norihisa; Iwamoto, Kojiro; Hogetsu, Taizo

    2014-05-01

    Numerous species of ectomycorrhizal (ECM) fungi coexist under the forest floor. To explore the mechanisms of coexistence, we investigated the fine-scale distribution of ECM fungal species colonizing root tips in the root system of Tsuga diversifolia seedlings in a subalpine forest. ECM root tips of three seedlings growing on the flat top surface of rocks were sampled after recording their positions in the root system. After the root tips were grouped by terminal-restriction fragment length polymorphism (T-RFLP) analysis of ITS rDNA, the fungal species representing each T-RFLP group were identified using DNA sequencing. Based on the fungal species identification, the distribution of root tips colonized by each ECM fungus was mapped. Significant clustering of root tips was estimated for each fungal species by comparing actual and randomly simulated distributions. In total, the three seedlings were colonized by 40 ECM fungal species. The composition of colonizing fungal species was quite different among the seedlings. Twelve of the 15 major ECM fungal species clustered significantly within a few centimeters. Some clusters overlapped or intermingled, while others were unique. Areas with high fungal species diversity were also identified in the root system. In this report, the mechanisms underlying generation of these ECM root tip clusters in the root system are discussed.

  9. Mercury bioaccumulation in fishes from subalpine lakes of the Wallowa-Whitman National Forest, northeastern Oregon and western Idaho

    Science.gov (United States)

    Eagles-Smith, Collin A.; Herring, Garth; Johnson, Branden L.; Graw, Rick

    2013-01-01

    Mercury (Hg) is a globally distributed pollutant that poses considerable risks to human and wildlife health. Over the past 150 years since the advent of the industrial revolution, approximately 80 percent of global emissions have come from anthropogenic sources, largely fossil fuel combustion. As a result, atmospheric deposition of Hg has increased by up to 4-fold above pre-industrial times. Because of their isolation, remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited Hg through freshwater food webs, as well as for evaluating the relative importance of Hg loading versus landscape influences on Hg bioaccumulation. The increase in Hg deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in Hg emissions may propagate to changes in Hg bioaccumulation and ecological risk. In this study, we evaluated Hg concentrations in fishes of high-elevation, sub-alpine lakes in the Wallowa-Whitman National Forest in northeastern Oregon and western Idaho. Our goals were to (1) assess the magnitude of Hg contamination in small-catchment lakes to evaluate the risk of atmospheric Hg to human and wildlife health, (2) quantify the spatial variability in fish Hg concentrations, and (3) determine the ecological, limnological, and landscape factors that are best correlated with fish total mercury (THg) concentrations in these systems. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. Importantly, our top statistical model explained 87 percent of the variability in fish THg concentrations among lakes with four key landscape and limnological variables— catchment conifer density (basal area of conifers within a lake’s catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. The basal area of conifers

  10. Response of palila and other subalpine Hawaiian forest bird species to prolonged drought and habitat degradation by feral ungulates

    Science.gov (United States)

    Banko, Paul C.; Camp, Richard J.; Farmer, Chris; Brinck, Kevin W.; Leonard, David L.; Stephens, Robert M.

    2013-01-01

    Extinction has claimed half of all historically-known Hawaiian passerines, and today many extant species are increasingly threatened due to the combined effects of invasive species and climate change. Habitat disturbance has affected populations of feeding specialists most profoundly, and our results indicate that specialists continue to be most vulnerable, although even some abundant, introduced, generalist species also may be affected. Surveys of passerines during 1998–2011 in subalpine woodland habitat on Mauna Kea Volcano, Island of Hawai′i, revealed that the abundance of the critically endangered palila (Loxioides bailleui), a seed specialist, declined by 79% after 2003. The ′akiapōlā′au (Hemignathus munroi), an endangered specialist insectivore, was not detected in the survey area after 1998. The Hawai′i ′amakihi (Hemignathus virens virens), a generalist feeder and the most abundant species on Mauna Kea, was the only native species to maintain a stable population. The Japanese white-eye (Zosterops japonicus), a well-entrenched generalist and one of the three most common introduced species, declined. Drought prevailed in 74% of months during 2000–2011, and dry conditions contributed to the recent decline of the palila by reducing the annual māmane (Sophora chrysophylla) seed pod crop, which influences palila breeding and survival. Sustained browsing by introduced ungulates also lowered habitat carrying capacity, and their elimination should reduce the effects of drought and promote forest restoration. Our results illustrate how the feeding ecology of a species can influence its response to interacting environmental perturbations, and they underscore the value of long-term monitoring to detect population trends of sensitive species.

  11. Vegetation types and climate conditions reflected by the modern phytolith assemblages in the subalpine Dalaoling Forest Reserve, central China

    Science.gov (United States)

    Traoré, Djakanibé Désiré; Gu, Yansheng; Liu, Humei; Shemsanga, Ceven; Ge, Jiwen

    2015-06-01

    This research describes modern phytolith records and distributions from subalpine surface soils in the Dalaoling Forest Reserve, and reveals its implications for local climate conditions with respect to the altitude gradient. Well-preserved phytolith morpho-types, assemblages, and climatic indices were used to study the relationship between local vegetation and climate conditions. The phytolith classification system is mainly based on the characteristics of detailed morpho-types described for anatomical terms, which are divided into seven groups: long cells, short cells, bulliform cells, hair cells, pteridophyte type, broad-leaved type, and gymnosperm type. Phytoliths originating from the Poaceae are composed of Pooideae (rondel and trapeziform), Panicoideae (bilobate, cross, and polylobate), Chloridoideae (short/square saddle), and Bambusoideae (oblong concave saddle). Based on the altitudinal distribution of the phytolith assemblages and the indices of aridity (Iph), climate (Ic), and tree cover density (D/P), five phytolith assemblage zones have revealed the five types of climatic conditions ranging from 1,169 m to 2,005 m in turn: warm-wet, warm-xeric to warm-mesic, warm-xeric to cool-mesic, cool-xeric, and cool-mesic to cool-xeric. The Bambusoideae, Panicoideae, and Chloridoideae are the dominant vegetation at the lower-middle of the mountains, while Pooideae is mainly distributed in the higher mountains. The close relationship between phytolith assembleages and changes of altitude gradient suggest that vegetation distribution patterns and plant ecology in the Dalaoling mountains are controlled by temperature and humidity conditions. Our results highlight the importance of phytolith records as reliable ecoclimatic indicators for vegetation ecology in subtropical regions.

  12. Examining the Physical Drivers of Photosynthetic Temperature Sensitivity Within a Sub-alpine Mixed Conifer Forest

    Science.gov (United States)

    Yang, J.; Barron-Gafford, G.; Minor, R.; Heard, M.

    2013-12-01

    Current projections of climate change in the southwestern U.S. suggest increasing temperatures and reduced summer precipitation. High temperature and water deficits have major influence on ecosystem functioning by restricting plant growth and productivity. However, there are limited data on what influences plant sensitivity to temperature, and these dynamics are not often captured in ecosystem models. Understanding the sensitivities, linkages, and feedbacks among biotic processes and abiotic forces is especially important within Critical Zone Sciences, which seeks to integrate among disciplines. Here, we analyzed several potential drivers of photosynthetic temperature sensitivity, including differences in soil parent material, aspect, and seasonality within a suite of species. Each of these variables captures a different physical driver: (i) soil parent material influences water holding capacity of the soil; (ii) aspect influences how incoming energy drives evaporative loss of soil water, creating warmer and drier environments on south/east faces; and (iii) seasonality captures temporal patterns of soil moisture recharge. Our research was conducted within two V shaped zero-order catchment basins of the Santa Catalina Critical Zone Observatory in southern Arizona, one with schist bedrock and the other with granite. We used leaf-level gas exchange measurements on 24 trees across a range of temperatures to quantify this plant temperature sensitivity during the dry pre-monsoon and wet monsoon seasons. Preliminary results show that maximum photosynthetic rate was 51% higher during the monsoon than pre-monsoon season. Optimal photosynthetic temperature decreased 25% while the span of functional temperatures (Ω50) was 21% higher following the onset of monsoon rains. During the rainy season, soil parent material became an important factor. The greater water holding capacity of schist soils yielded greater maximum photosynthesis and reduced tree sensitivity to higher

  13. Mercury in forest mushrooms and topsoil from the Yunnan highlands and the subalpine region of the Minya Konka summit in the Eastern Tibetan Plateau.

    Science.gov (United States)

    Falandysz, Jerzy; Saba, Martyna; Liu, Hong-Gao; Li, Tao; Wang, Ji-Peng; Wiejak, Anna; Zhang, Ji; Wang, Yuan-Zhong; Zhang, Dan

    2016-12-01

    This study aimed to investigate and discuss the occurrence and accumulation of mercury in the fruiting bodies of wild-growing fungi (Macromycetes) collected from montane forests in two regions of southwestern China with differences in soil geochemistry, climate and geographical conditions. Fungal mycelia in soils of the subalpine region of the Minya Konka (Gongga Mountain) in Sichuan and in the highlands of Yunnan efficiently accumulated mercury in fruiting bodies (mushrooms). The examined sites in Yunnan with highly mineralized red and yellow soils showed Hg contents ranging from 0.066 to 0.28 mg kg -1 dry biomass (db) which is roughly similar to the results obtained for samples collected from sites with dark soils relatively rich in organic matter from a remote, the subalpine region of Minya Konka. Due to the remoteness of the subalpine section of Minya Konka, as well as its elevation and climate, airborne mercury from long-range transport could be deposited preferentially on the topsoil and the Hg levels determined in soil samples taken beneath the fruiting bodies were up to 0.48 mg kg -1 dry matter. In Yunnan, with polymetallic soils (Circum-Pacific Mercuriferous Belt), Amanita mushrooms showed mercury in caps of fruiting bodies of up to 7.3 mg kg -1 dry biomass. Geogenic Hg from the mercuriferous belt seems to be the overriding source of mercury accumulated in mushrooms foraged in the regions of Yunnan, while long-range atmospheric transport and subsequent deposition are the mercury sources for specimens foraged in the region of Minya Konka.

  14. Responses of Sap Flow of Deciduous and Conifer Trees to Soil Drying in a Subalpine Forest

    Directory of Open Access Journals (Sweden)

    Chunhua Yan

    2018-01-01

    Full Text Available Co-occurring species may adopt different water-use strategies to adapt to limited soil water. In Jiuzhaigou Valley, a continuous decline in soil water after an initial recharge from the thawing of snow and frozen soil in early spring was observed, but its effects on the sap flow dynamics of co-occurring species are not well understood. To clarify the species-specific water-use strategy, variations in sap flow and environmental conditions were investigated for two co-occurring species (Betula albosinensis Burk. and Pinus tabuliaeformis Carr. in a mixed forest during a transition from the wet to dry period in 2014. Sap flow was measured using Granier-type thermal dissipation probes, and the soil-water content was measured using time-domain reflectometry probes for a successive period. Our study showed that B. albosinensis maintained relatively high transpiration until late into the season regardless of soil moisture, while the transpiration of P. tabuliformis showed a continuous decrease in response to seasonal soil drying. Sap flow for both species exhibited a marked hysteresis in response to meteorological factors and it was conditioned by the soil-water status, especially in the afternoon. We found that P. tabuliformis was sensitive to soil-water conditions, while for B. albosinensis, the sap flow was not very sensitive to changes in soil-water conditions. These results indicate that B. albosinensis could manage the water consumption conservatively under both dry and wet conditions. These results may have implications for evaluating the species-specific water-use strategy and carrying out proper reforestation practices.

  15. Long-term landscape changes in a subalpine spruce-fir forest in central Utah, USA

    Science.gov (United States)

    Jesse L. Morris; R. Justin DeRose; Andrea R. Brunelle

    2015-01-01

    In Western North America, increasing wildfire and outbreaks of native bark beetles have been mediated by warming climate conditions. Bioclimatic models forecast the loss of key high elevation species throughout the region. This study uses retrospective vegetation and fire history data to reconstruct the drivers of past disturbance and environmental change....

  16. Pre-outbreak forest conditions mediate the effects of spruce beetle outbreaks on fuels in subalpine forests of Colorado.

    Science.gov (United States)

    Mietkiewicz, Nathan; Kulakowski, Dominik; Veblen, Thomas T

    2018-03-01

    Over the past 30 years, forest disturbances have increased in size, intensity, and frequency globally, and are predicted to continue increasing due to climate change, potentially relaxing the constraints of vegetation properties on disturbance regimes. However, the consequences of the potentially declining importance of vegetation in determining future disturbance regimes are not well understood. Historically, bark beetles preferentially attack older trees and stands in later stages of development. However, as climate warming intensifies outbreaks by promoting growth of beetle populations and compromising tree defenses, smaller diameter trees and stands in early stages of development now are being affected by outbreaks. To date, no study has considered how stand age and other pre-outbreak forest conditions mediate the effects of outbreaks on surface and aerial fuel arrangements. We collected fuels data across a chronosequence of post-outbreak sites affected by spruce beetle (SB) between the 1940s and the 2010s, stratified by young (130 yr) post-fire stands. Canopy and surface fuel loads were calculated for each tree and stand, and available crown fuel load, crown bulk density, and canopy bulk densities were estimated. Canopy bulk density and density of live canopy individuals were reduced in all stands affected by SB, though foliage loss was proportionally greater in old stands as compared to young stands. Fine surface fuel loads in young stands were three times greater shortly (fuels decreased to below endemic (i.e., non-outbreak) levels. In both young and old stands, the net effect of SB outbreaks during the 20th and 21st centuries reduced total canopy fuels and increased stand-scale spatial heterogeneity of canopy fuels following outbreak. Importantly, the decrease in canopy fuels following outbreaks was greater in young post-fire stands than in older stands, suggesting that SB outbreaks may more substantially reduce risk of active crown fire when they affect

  17. Modeled subalpine plant community response to climate change and atmospheric nitrogen deposition in Rocky Mountain National Park, USA

    International Nuclear Information System (INIS)

    McDonnell, T.C.; Belyazid, S.; Sullivan, T.J.; Sverdrup, H.; Bowman, W.D.; Porter, E.M.

    2014-01-01

    To evaluate potential long-term effects of climate change and atmospheric nitrogen (N) deposition on subalpine ecosystems, the coupled biogeochemical and vegetation community competition model ForSAFE-Veg was applied to a site at the Loch Vale watershed of Rocky Mountain National Park, Colorado. Changes in climate and N deposition since 1900 resulted in pronounced changes in simulated plant species cover as compared with ambient and estimated future community composition. The estimated critical load (CL) of N deposition to protect against an average future (2010–2100) change in biodiversity of 10% was between 1.9 and 3.5 kg N ha −1  yr −1 . Results suggest that the CL has been exceeded and vegetation at the study site has already undergone a change of more than 10% as a result of N deposition. Future increases in air temperature are forecast to cause further changes in plant community composition, exacerbating changes in response to N deposition alone. - Highlights: • A novel calibration step was introduced for modeling biodiversity with ForSAFE-Veg. • Modeled increases in tree cover are consistent with empirical studies. • Reductions in N deposition decreased future graminoid percent cover. • Critical loads of N to protect biodiversity should consider climate change effects. - Subalpine plant biodiversity in Rocky Mountain National Park has already been impacted by N deposition and climate change and is expected to experience significant future effects

  18. Forest-fire models

    Science.gov (United States)

    Haiganoush Preisler; Alan Ager

    2013-01-01

    For applied mathematicians forest fire models refer mainly to a non-linear dynamic system often used to simulate spread of fire. For forest managers forest fire models may pertain to any of the three phases of fire management: prefire planning (fire risk models), fire suppression (fire behavior models), and postfire evaluation (fire effects and economic models). In...

  19. Exploring the landscape evolution of the subalpine meadow-forest system driven by the geomorphic work performed by the Northern Pocket Gopher

    Science.gov (United States)

    Winchell, E. W.; Anderson, R. S.; Lombardi, E. M.; Doak, D. F.

    2015-12-01

    In the subalpine zone of the Colorado Front Range, field observations suggest that the Northern Pocket Gopher acts as a significant geomorphic agent within meadows, but not within forests. Field surveys during 2014 and 2015 demonstrate that the temporal and spatial digging patterns of gopher-excavated mounds and infilled tunnels are neither steady nor uniform. These include 1) gophers spend the winter near the forest-meadow (FM) edge and the remainder of the year within the meadow, and 2) surface mound generation greatly accelerates in late summer. Hourly subsurface temperatures across the FM pair, and daily digital snow depths at the FM boundary suggest that gophers spend the winter beneath thick snow cover where ground temperatures are warmest. LiDAR-based topography demonstrates that slopes are uniform across the FM pairs, diverging from that expected by extrapolation of the observed pattern of non-uniform geomorphic activity. The topography therefore suggests that the FM boundaries are not stationary. We hypothesize that the landscape is more uniformly impacted by gopher activity in the long term, which requires that 1) FM boundaries migrate significantly and/or 2) meadows are born in different places following forest death via fire followed by rapid gopher habitation. The vertical geomorphic signature of gopher activity is more distinct. Preliminary probing of meadows reveals a 20 cm thick biomantle with a high concentration of stones at ~20 cm depth. The annual surface areas of mounds and infilled tunnels suggest that the entire meadow can be exposed to excavated tillings on century timescales. Further, annual mound volumes suggest that the biomantle is turned over also on century timescales. We will report results of stone line surveys and 137Cs concentration profiles within the forest and meadow that will test the long-term stability of meadows and the timescale over which vertical churning mixes the near-surface material within this landscape.

  20. Effects of elevated CO{sub 2} and temperature on photosynthesis and leaf traits of an understory dwarf bamboo in subalpine forest zone, China

    Energy Technology Data Exchange (ETDEWEB)

    Yongping Li; Yuanbin Zhang; Xiaolu Zhang; Chunyang Li [Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu (China); Korpelainenc, H. [Univ. of Helsinki. Dept. of Agricultural Sciences, Helsinki (Finland); Berningerd, F. [Univ. of Helsinki. Dept. of Forest Sciences, Helsinki (Finland)

    2013-06-01

    The dwarf bamboo (Fargesia rufa Yi), growing understory in subalpine dark coniferous forest, is one of the main foods for giant panda, and it influences the regeneration of subalpine coniferous forests in southwestern China. To investigate the effects of elevated CO{sub 2}, temperature and their combination, the dwarf bamboo plantlets were exposed to two CO{sub 2} regimes (ambient and double ambient CO{sub 2} concentration) and two temperatures (ambient and +2.2 deg. C) in growth chambers. Gas exchange, leaf traits and carbohydrates concentration were measured after the 150-day experiment. Elevated CO{sub 2} significantly increased the net photosynthetic rate (A{sub net}), intrinsic water-use efficiency (WUE{sub i}) and carbon isotope composition ({delta}{sup 13}C) and decreased stomatal conductance (g{sub s}) and total chlorophyll concentration based on mass (Chl{sub m}) and area (Chl{sub a}). On the other hand, elevated CO{sub 2} decreased specific leaf area (SLA), which was increased by elevated temperature. Elevated CO{sub 2} also increased foliar carbon concentration based on mass (C{sub m}) and area (C{sub a}), nitrogen concentration based on area (N{sub a}), carbohydrates concentration (i.e. sucrose, sugar, starch and non-structural carbohydrates) and the slope of the A{sub net}-N{sub a} relationship. However, elevated temperature decreased C{sub m}, C{sub a} and N{sub a}. The combination of elevated CO{sub 2} and temperature hardly affected SLA, C{sub m}, C{sub a}, N{sub m}, N{sub a}, Chl{sub m} and Chl{sub a}. Variables A{sub net} and N{sub a} had positive linear relationships in all treatments. Our results showed that photosynthetic acclimation did not occur in dwarf bamboo at elevated CO{sub 2} and it could adjust physiology and morphology to enable the capture of more light, to increase WUE and improve nutritional conditions. (Author)

  1. Trait-Based Community Assembly along an Elevational Gradient in Subalpine Forests: Quantifying the Roles of Environmental Factors in Inter- and Intraspecific Variability.

    Directory of Open Access Journals (Sweden)

    Ya-Huang Luo

    Full Text Available Understanding how communities respond to environmental variation is a central goal in ecology. Plant communities respond to environmental gradients via intraspecific and/or interspecific variation in plant functional traits. However, the relative contribution of these two responses to environmental factors remains poorly tested. We measured six functional traits (height, leaf thickness, specific leaf area (SLA, leaf carbon concentration (LCC, leaf nitrogen concentration (LNC and leaf phosphorus concentration (LPC for 55 tree species occurring at five elevations across a 1200 m elevational gradient of subalpine forests in Yulong Mountain, Southwest China. We examined the relative contribution of interspecific and intraspecific traits variability based on community weighted mean trait values and functional diversity, and tested how different components of trait variation respond to different environmental axes (climate and soil variables. Species turnover explained the largest amount of variation in leaf morphological traits (leaf thickness and SLA across the elevational gradient. However, intraspecific variability explained a large amount of variation (49.3%-76.3% in three other traits (height, LNC and LPC despite high levels of species turnover. The detection of limiting similarity in community assembly was improved when accounting for both intraspecific and interspecific variability. Different components of trait variation respond to different environmental axes, especially soil water content and climatic variables. Our results indicate that intraspecific variation is critical for understanding community assembly and evaluating community response to environmental change.

  2. Trait-Based Community Assembly along an Elevational Gradient in Subalpine Forests: Quantifying the Roles of Environmental Factors in Inter- and Intraspecific Variability.

    Science.gov (United States)

    Luo, Ya-Huang; Liu, Jie; Tan, Shao-Lin; Cadotte, Marc William; Wang, Yue-Hua; Xu, Kun; Li, De-Zhu; Gao, Lian-Ming

    2016-01-01

    Understanding how communities respond to environmental variation is a central goal in ecology. Plant communities respond to environmental gradients via intraspecific and/or interspecific variation in plant functional traits. However, the relative contribution of these two responses to environmental factors remains poorly tested. We measured six functional traits (height, leaf thickness, specific leaf area (SLA), leaf carbon concentration (LCC), leaf nitrogen concentration (LNC) and leaf phosphorus concentration (LPC)) for 55 tree species occurring at five elevations across a 1200 m elevational gradient of subalpine forests in Yulong Mountain, Southwest China. We examined the relative contribution of interspecific and intraspecific traits variability based on community weighted mean trait values and functional diversity, and tested how different components of trait variation respond to different environmental axes (climate and soil variables). Species turnover explained the largest amount of variation in leaf morphological traits (leaf thickness and SLA) across the elevational gradient. However, intraspecific variability explained a large amount of variation (49.3%-76.3%) in three other traits (height, LNC and LPC) despite high levels of species turnover. The detection of limiting similarity in community assembly was improved when accounting for both intraspecific and interspecific variability. Different components of trait variation respond to different environmental axes, especially soil water content and climatic variables. Our results indicate that intraspecific variation is critical for understanding community assembly and evaluating community response to environmental change.

  3. Moisture availability limits subalpine tree establishment.

    Science.gov (United States)

    Andrus, Robert A; Harvey, Brian J; Rodman, Kyle C; Hart, Sarah J; Veblen, Thomas T

    2018-03-01

    In the absence of broad-scale disturbance, many temperate coniferous forests experience successful seedling establishment only when abundant seed production coincides with favorable climate. Identifying the frequency of past establishment events and the climate conditions favorable for seedling establishment is essential to understanding how climate warming could affect the frequency of future tree establishment events and therefore future forest composition or even persistence of a forest cover. In the southern Rocky Mountains, USA, research on the sensitivity of establishment of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa)-two widely distributed, co-occurring conifers in North America-to climate variability has focused on the alpine treeline ecotone, leaving uncertainty about the sensitivity of these species across much of their elevation distribution. We compared annual germination dates for >450 Engelmann spruce and >500 subalpine fir seedlings collected across a complex topographic-moisture gradient to climate variability in the Colorado Front Range. We found that Engelmann spruce and subalpine fir established episodically with strong synchrony in establishment events across the study area. Broad-scale establishment events occurred in years of high soil moisture availability, which were characterized by above-average snowpack and/or cool and wet summer climatic conditions. In the recent half of the study period (1975-2010), a decrease in the number of fir and spruce establishment events across their distribution coincided with declining snowpack and a multi-decadal trend of rising summer temperature and increasing moisture deficits. Counter to expected and observed increases in tree establishment with climate warming in maritime subalpine forests, our results show that recruitment declines will likely occur across the core of moisture-limited subalpine tree ranges as warming drives increased moisture deficits. © 2018 by the

  4. Evaluating the utility and seasonality of NDVI values for assessing post-disturbance recovery in a subalpine forest.

    Science.gov (United States)

    Buma, Brian

    2012-06-01

    Forest disturbances around the world have the potential to alter forest type and cover, with impacts on diversity, carbon storage, and landscape composition. These disturbances, especially fire, are common and often large, making ground investigation of forest recovery difficult. Remote sensing offers a means to monitor forest recovery in real time, over the entire landscape. Typically, recovery monitoring via remote sensing consists of measuring vegetation indices (e.g., NDVI) or index-derived metrics, with the assumption that recovery in NDVI (for example) is a meaningful measure of ecosystem recovery. This study tests that assumption using MODIS 16-day imagery from 2000 to 2010 in the area of the Colorado's Routt National Forest Hinman burn (2002) and seedling density counts taken in the same area. Results indicate that NDVI is rarely correlated with forest recovery, and is dominated by annual and perennial forb cover, although topography complicates analysis. Utility of NDVI as a means to delineate areas of recovery or non-recovery are in doubt, as bootstrapped analysis indicates distinguishing power only slightly better than random. NDVI in revegetation analyses should carefully consider the ecology and seasonal patterns of the system in question.

  5. Hydrologic Impacts of Wildfire on a Small Sub-alpine Southwestern U.S. Watershed: A Simplified Modeling Approach

    Science.gov (United States)

    Moeser, D.; Douglas-Mankin, K.

    2017-12-01

    A Precipitation-Runoff Modeling System (PRMS) based on the National Hydrological Model (NHM) framework was initially developed to determine the extent to which an NHM-based PRMS model can assess effects of fire on watershed-scale hydrologic response. Pre- and post-fire models were calibrated using observed streamflow for a small subalpine Southwestern U.S. watershed located in a monsoon-dominated summer precipitation regime. Streamflow component and parameter response between the two models were then compared. Cumulative runoff was much greater for simulated post-fire conditions. However, if streamflow was partitioned with soil moisture, the models demonstrated that the largest differences between streamflow efficiency for pre- and post-fire watershed response were at moderate antecedent soil moisture conditions. For example, when precipitation occurred in the watershed at low and moderate antecedent soil moisture conditions, the post-fire modeled watershed generated substantial runoff (higher runoff efficiency) whereas the pre-fire model generated almost none (near-zero runoff efficiency). When antecedent soil moisture conditions were high, the pre- and post- fire models demonstrated an almost equivalent ability (though both were highly variable) to generate runoff at all precipitation event sizes (equivalent range of runoff efficiency). In this watershed, the post-fire landscape runoff was increasingly sensitive to soil moisture across all soil-moisture conditions whereas the pre-fire landscape was only responsive to soil moisture at the highest soil moisture-levels. Study results indicate that the rainfall-runoff relationship to soil moisture may be a key aspect of landscape vulnerability to post-fire flooding. Practical implications of this study are that soil moisture may be a useful parameter for monitoring post-fire landscape response and recovery, and that post-fire recovery efforts should be oriented toward establishing pre-fire soil

  6. Streamwater Chemistry and Nutrient Export During Five Years of Bark Beetle Infestation of Subalpine Watersheds at the Fraser Experimental Forest

    Science.gov (United States)

    Rhoades, C.; Elder, K.; Hubbard, R.; Porth, L.

    2008-12-01

    Forested watersheds of western North America are currently undergoing rapid and extensive canopy mortality caused by a variety of insect species. The mountain pine bark beetle (Dendroctonus ponderosae) began to attack lodgepole pine (Pinus contorta) at the USFS Fraser Experimental Forest in central Colorado in 2002. By 2007, bark beetles had killed 78% of the overstory pine in Fraser research watersheds on average. The hydrologic, climatic, biogeochemical and vegetation records at the Fraser Experimental Forest provide a unique opportunity to quantify the impacts of this widespread, but poorly understood forest disturbance relative to a multi-decade pre-disturbance period. Here we compare seasonal streamwater chemistry and annual nutrient export for the five years since the bark beetle outbreak began with the pre- attack record. Patterns in post-outbreak streamwater biogeochemistry are compared to changes is species composition and proportional loss of overstory basal area for four basins. The influence of the outbreak will depend upon an aggregate of short (i.e. halted overstory water and nutrient use) and longer-term (i.e. altered canopy interception, windthrow, and understory growth) processes, so the hydrologic and biogeochemical implications of current beetle activity will not be fully realized for decades.

  7. Modeling species’ realized climatic niche space and predicting their response to global warming for several western forest species with small geographic distributions

    Science.gov (United States)

    Marcus V. Warwell; Gerald E. Rehfeldt; Nicholas L. Crookston

    2010-01-01

    The Random Forests multiple regression tree was used to develop an empirically based bioclimatic model of the presence-absence of species occupying small geographic distributions in western North America. The species assessed were subalpine larch (Larix lyallii), smooth Arizona cypress (Cupressus arizonica ssp. glabra...

  8. Fire, fuel composition and resilience threshold in subalpine ecosystem.

    Directory of Open Access Journals (Sweden)

    Olivier Blarquez

    Full Text Available BACKGROUND: Forecasting the effects of global changes on high altitude ecosystems requires an understanding of the long-term relationships between biota and forcing factors to identify resilience thresholds. Fire is a crucial forcing factor: both fuel build-up from land-abandonment in European mountains, and more droughts linked to global warming are likely to increase fire risks. METHODS: To assess the vegetation response to fire on a millennium time-scale, we analyzed evidence of stand-to-local vegetation dynamics derived from sedimentary plant macroremains from two subalpine lakes. Paleobotanical reconstructions at high temporal resolution, together with a fire frequency reconstruction inferred from sedimentary charcoal, were analyzed by Superposed Epoch Analysis to model plant behavior before, during and after fire events. PRINCIPAL FINDINGS: We show that fuel build-up from arolla pine (Pinus cembra always precedes fires, which is immediately followed by a rapid increase of birch (Betula sp., then by ericaceous species after 25-75 years, and by herbs after 50-100 years. European larch (Larix decidua, which is the natural co-dominant species of subalpine forests with Pinus cembra, is not sensitive to fire, while the abundance of Pinus cembra is altered within a 150-year period after fires. A long-term trend in vegetation dynamics is apparent, wherein species that abound later in succession are the functional drivers, loading the environment with fuel for fires. This system can only be functional if fires are mainly driven by external factors (e.g. climate, with the mean interval between fires being longer than the minimum time required to reach the late successional stage, here 150 years. CONCLUSION: Current global warming conditions which increase drought occurrences, combined with the abandonment of land in European mountain areas, creates ideal ecological conditions for the ignition and the spread of fire. A fire return interval of less

  9. Fire, fuel composition and resilience threshold in subalpine ecosystem.

    Science.gov (United States)

    Blarquez, Olivier; Carcaillet, Christopher

    2010-08-30

    Forecasting the effects of global changes on high altitude ecosystems requires an understanding of the long-term relationships between biota and forcing factors to identify resilience thresholds. Fire is a crucial forcing factor: both fuel build-up from land-abandonment in European mountains, and more droughts linked to global warming are likely to increase fire risks. To assess the vegetation response to fire on a millennium time-scale, we analyzed evidence of stand-to-local vegetation dynamics derived from sedimentary plant macroremains from two subalpine lakes. Paleobotanical reconstructions at high temporal resolution, together with a fire frequency reconstruction inferred from sedimentary charcoal, were analyzed by Superposed Epoch Analysis to model plant behavior before, during and after fire events. We show that fuel build-up from arolla pine (Pinus cembra) always precedes fires, which is immediately followed by a rapid increase of birch (Betula sp.), then by ericaceous species after 25-75 years, and by herbs after 50-100 years. European larch (Larix decidua), which is the natural co-dominant species of subalpine forests with Pinus cembra, is not sensitive to fire, while the abundance of Pinus cembra is altered within a 150-year period after fires. A long-term trend in vegetation dynamics is apparent, wherein species that abound later in succession are the functional drivers, loading the environment with fuel for fires. This system can only be functional if fires are mainly driven by external factors (e.g. climate), with the mean interval between fires being longer than the minimum time required to reach the late successional stage, here 150 years. Current global warming conditions which increase drought occurrences, combined with the abandonment of land in European mountain areas, creates ideal ecological conditions for the ignition and the spread of fire. A fire return interval of less than 150 years would threaten the dominant species and might override

  10. Mycorrhiza-plant colonization patterns on a subalpine glacier forefront as a model system of primary succession

    Science.gov (United States)

    Efren Cazares; James M. Trappe; Ari Jumpponen

    2005-01-01

    Lyman glacier in the North Cascades Mountains of Washington has a subalpine forefront characterized by a well-developed terminal moraine, inconspicuous successional moraines, fluting, and outwash. These deposits were depleted of symbiotic fungi when first exposed but colonized by them over time after exposure. Four major groups of plant species in this system are (1)...

  11. Primary and secondary effects of climate variability on carbon and water exchange in a managed subalpine Eucalyptus forest.

    Science.gov (United States)

    van Gorsel, Eva; Berni, Jose. A. J.; Briggs, Peter; Cabello-Leblic, Arancha; Chasmer, Laura; Cleugh, Helen A.; Hacker, Joerg; Hantson, Stijn; Haverd, Vanessa; Hughes, Dale; Hopkinson, Chris; Keith, Heather; Kljun, Natascha; Leuning, Ray; Yebra, Marta; Zegelin, Steve

    2013-04-01

    Climate variability and change, ecosystem disturbance and land management operate over a large range of temporal and spatial scales and lead to variability in carbon and water fluxes. Diagnosing the climate controls over these fluxes is not simple but key to improving prediction and understanding of water and carbon cycle-climate interactions. We use a novel technique to investigate the variability of the fluxes from daily to multiannual timescales. We rank direct controlling factors of climate on water use and carbon uptake (changes in radiation, temperature, humidity) and indirect factors (disturbance triggered by changes in climate conditions). Direct climate impacts depend on the time scale under consideration but are generally strongest on the annual time scale. To investigate the spatio-temporal variability caused by disturbance we use NDVI and albedo. They provide information on status and dynamics of the vegetation and we find that the whole area within Bago State Forest that was classified as native Eucalyptus forest (305.05 km2) was affected by a disturbance by insect attack. This disturbance affected tree species differently, led to a reduced photosynthetically active leaf area, reduced canopy conductance and hence photosynthetic capacity. The reduced net carbon uptake of the trees was evident as reduced biomass increment and increased mortality was observed. Net ecosystem exchange measurements at the Tumbarumba flux tower indicate that the ecosystem turned from a generally strong carbon sink to a source. We further find that the coherence between albedo and carbon and water exchange is strong on annual and multi-annual time scales. At a multi-annual time scale, carbon and water fluxes are coherent with the multivariate El Niño index.

  12. Leap frog in slow motion: Divergent responses of tree species and life stages to climatic warming in Great Basin subalpine forests

    Science.gov (United States)

    Brian V. Smithers; Malcolm P. North; Constance I. Millar; Andrew M. Latimer

    2017-01-01

    In response to climate warming, subalpine treelines are expected to move up in elevation since treelines are generally controlled by growing season temperature. Where treeline is advancing, dispersal differences and early life stage environmental tolerances are likely to affect how species expand their ranges. Species with an establishment advantage will...

  13. Leap frog in slow motion: Divergent responses of tree species and life stages to climatic warming in Great Basin subalpine forests

    OpenAIRE

    Smithers, Brian V; North, Malcolm P; Millar, Constance I; Latimer, Andrew M

    2017-01-01

    In response to climate warming, subalpine treelines are expected to move up in elevation since treelines are generally controlled by growing season temperature. Where treeline is advancing, dispersal differences and early life stage environmental tolerances are likely to affect how species expand their ranges. Species with an establishment advantage will colonize newly available habitat first, potentially excluding species that have slower establishment rates. Using a network of plots across ...

  14. The Response of Subalpine Vegetation to Climate Change and Bark Beetle Infestations: A Multi-Scale Interaction.

    Science.gov (United States)

    Foster, A.; Shuman, J. K.; Shugart, H. H., Jr.; Negrón, J. F.

    2015-12-01

    Mean annual temperatures in the western United States have increased in the last few decades, and are predicted to continue warming. In the subalpine zone of the Rocky Mountains, this warming is also predicted to increase the frequency and severity of spruce beetle outbreaks. Climate change itself may affect this vegetation, potentially leading to shifts in species compositions. These forests are a crucial part of the US's carbon budget, thus it is important to analyze how climate change and bark beetles in conjunction will affect the biomass and species composition of vegetation in subalpine zone. UVAFME is an individual-based gap model that simulates biomass and species composition of a forest. This model has been quantitatively tested at various Rocky Mountain sites in the Front Range, and has been shown to accurately simulate the vegetation dynamics in the region. UVAFME has been updated with a spruce beetle subroutine that calculates the probability for beetle infestation of each tree on a plot. This probability is based on site, climate, and individual tree characteristics, such as temperature; stand structure; and tree stress level, size, and age. These governing characteristics are based on data from the US Forest Service, and other studies on spruce susceptibility and spruce beetle phenology. UVAFME is then run with multiple climate change and beetle scenarios to determine the net effect of both variables on subalpine vegetation. These results are compared among the different scenarios and to current forest inventory data. We project that increasing temperatures due to climate change will cause an increase in the frequency and severity of spruce beetle outbreaks, leading to a decrease in the biomass and dominance of Engelmann spruce. These results are an important step in understanding the possible futures for the vegetation of subalpine zone in the Rocky Mountains.

  15. Comparison of remote sensing and plant trait-based modelling to predict ecosystem services in subalpine grasslands

    Czech Academy of Sciences Publication Activity Database

    Homolová, Lucie; Schaepman, M. E.; Lamarque, L.; Clevers, J.G.P.W.; de Bello, Francesco; Thuiller, W.; Lavorel, S.

    2014-01-01

    Roč. 5, č. 8 (2014), č. článku 100. ISSN 2150-8925 Institutional support: RVO:67179843 ; RVO:67985939 Keywords : land-use change * leaf chlorophyll content * imaging spectroscopy * water-content * aviris data * spectral reflectance * hyperspectral data * species richness * area index * vegetation * aisa * biomass * ecosystem properties * ecosystem services * linear regression * remote sensing * spatial heterogeneity * subalpine grasslands Subject RIV: EH - Ecology, Behaviour; EF - Botanics (BU-J) OBOR OECD: Remote sensing; Plant sciences, botany (BU-J) Impact factor: 2.255, year: 2014

  16. Hydrological modelling in forested systems

    Science.gov (United States)

    This chapter provides a brief overview of forest hydrology modelling approaches for answering important global research and management questions. Many hundreds of hydrological models have been applied globally across multiple decades to represent and predict forest hydrological p...

  17. Forecasting the evolution in the mixing regime of a deep subalpine lake under climate change scenarios through numerical modelling (Lake Maggiore, Northern Italy/Southern Switzerland)

    Science.gov (United States)

    Fenocchi, Andrea; Rogora, Michela; Sibilla, Stefano; Ciampittiello, Marzia; Dresti, Claudia

    2018-01-01

    The impact of air temperature rise is eminent for the large deep lakes in the Italian subalpine district, climate change being caused there by both natural phenomena and anthropogenic greenhouse-gases (GHG) emissions. These oligomictic lakes are experiencing a decrease in the frequency of winter full turnover and an intensification of stability. As a result, hypolimnetic oxygen concentrations are decreasing and nutrients are accumulating in bottom water, with effects on the whole ecosystem functioning. Forecasting the future evolution of the mixing pattern is relevant to assess if a reduction in GHG releases would be able to revert such processes. The study focuses on Lake Maggiore, for which the thermal structure evolution under climate change in the 2016-2085 period was assessed through numerical simulations, performed with the General Lake Model (GLM). Different prospects of regional air temperature rise were considered, given by the Swiss Climate Change Scenarios CH2011. Multiple realisations were performed for each scenario to obtain robust statistical predictions, adopting random series of meteorological data produced with the Vector-Autoregressive Weather Generator (VG). Results show that a reversion in the increasing thermal stability would be possible only if global GHG emissions started to be reduced by 2020, allowing an equilibrium mixing regime to be restored by the end of the twenty-first century. Otherwise, persistent lack of complete-mixing, severe water warming and extensive effects on water quality are to be expected for the centuries to come. These projections can be extended to the other lakes in the subalpine district.

  18. Leap frog in slow motion: Divergent responses of tree species and life stages to climatic warming in Great Basin subalpine forests.

    Science.gov (United States)

    Smithers, Brian V; North, Malcolm P; Millar, Constance I; Latimer, Andrew M

    2018-02-01

    In response to climate warming, subalpine treelines are expected to move up in elevation since treelines are generally controlled by growing season temperature. Where treeline is advancing, dispersal differences and early life stage environmental tolerances are likely to affect how species expand their ranges. Species with an establishment advantage will colonize newly available habitat first, potentially excluding species that have slower establishment rates. Using a network of plots across five mountain ranges, we described patterns of upslope elevational range shift for the two dominant Great Basin subalpine species, limber pine and Great Basin bristlecone pine. We found that the Great Basin treeline for these species is expanding upslope with a mean vertical elevation shift of 19.1 m since 1950, which is lower than what we might expect based on temperature increases alone. The largest advances were on limber pine-dominated granitic soils, on west aspects, and at lower latitudes. Bristlecone pine juveniles establishing above treeline share some environmental associations with bristlecone adults. Limber pine above-treeline juveniles, in contrast, are prevalent across environmental conditions and share few environmental associations with limber pine adults. Strikingly, limber pine is establishing above treeline throughout the region without regard to site characteristic such as soil type, slope, aspect, or soil texture. Although limber pine is often rare at treeline where it coexists with bristlecone pine, limber pine juveniles dominate above treeline even on calcareous soils that are core bristlecone pine habitat. Limber pine is successfully "leap-frogging" over bristlecone pine, probably because of its strong dispersal advantage and broader tolerances for establishment. This early-stage dominance indicates the potential for the species composition of treeline to change in response to climate change. More broadly, it shows how species differences in dispersal

  19. Modelling mixed forest growth : a review of models for forest management

    NARCIS (Netherlands)

    Porte, A.; Bartelink, H.H.

    2002-01-01

    Most forests today are multi-specific and heterogeneous forests (`mixed forests'). However, forest modelling has been focusing on mono-specific stands for a long time, only recently have models been developed for mixed forests. Previous reviews of mixed forest modelling were restricted to certain

  20. Forest-management modelling

    Science.gov (United States)

    Mark J. Twery; Aaron R. Weiskittel

    2013-01-01

    Forests are complex and dynamic ecosystems comprising individual trees that can vary in both size and species. In comparison to other organisms, trees are relatively long lived (40-2000 years), quite plastic in terms of their morphology and ecological niche, and adapted to a wide variety of habitats, which can make predicting their behaviour exceedingly difficult....

  1. Drivers of variability in water use of two co-occurring species in a subalpine forest in Jiuzhaigou Valley, Southwest of China

    Science.gov (United States)

    Yan, C.; Zhao, W.; Wang, Y.; Zhang, Q.; Qiu, G. Y.

    2016-12-01

    Co-occur species with different sensitivity to soil water may be particularly useful in evaluating water use by different forest stands as well as the response of species distribution, forest structure and stand composition to soil water availability in water-limited area. To clarify the species-specific water use strategy and provide insights into the possible succession trend, variations in sap flow and environmental conditions were investigated for two co-occur species (Betula albo-sinensis and Pinus tabulaeformis) in a mixed forest in Jiuzhaigou Valley in 2014. Sap flow was measured by Granier-type thermal dissipation probes and soil water content was measured by time-domain reflectometry probes for a successive period. Pinus tabulaeformis and Betua albo-sinensis species showed different responses to meteorological factors under different soil water conditions. Despite that whole tree water use was much higher for Pinus tabulaeformis due to greater sapwood area, sap flux density of the other co-occurring species Betua albo-sinensis was higher throughout the growing season. Normalized sap flux density (Fd) could be mostly well fitted to solar radiation (Rs), vapor pressure deficit (VPD), or the variable of transpiration (VT) by the exponential saturation function. Much better fitted curves were found for Fd -VPD and Fd - VT datasets than Fd - Rs datasets. For most datasets, normalized Fd increased rapidly when the environmental factors were below their threshold values, but reached an asymptote thereafter. Based on the species' differences in fitting parameters and the average maximum sap flow level under different soil water conditions, it was concluded that Pinus tabulaeformis was sensitive to soil water conditions and tolerant of low soil water availability, while Betua albo-sinensis was insensitive to soil moisture and needed to access to similarly high amount of soil water in the growing season after leaf expansion. These results indicated possible

  2. Climate change effects on vegetation in the Pacific Northwest: a review and synthesis of the scientific literature and simulation model projections

    Science.gov (United States)

    David W. Peterson; Becky K. Kerns; Erich Kyle Dodson

    2014-01-01

    The purpose of this study was to review scientifi c knowledge and model projections on vegetation vulnerability to climatic and other environmental changes in the Pacifi c Northwest, with emphasis on fi ve major biome types: subalpine forests and alpine meadows, maritime coniferous forests, dry coniferous forests, savannas and woodlands (oak and juniper), and interior...

  3. Hydrological modeling in forested systems

    Science.gov (United States)

    H.E. Golden; G.R. Evenson; S. Tian; Devendra Amatya; Ge Sun

    2015-01-01

    Characterizing and quantifying interactions among components of the forest hydrological cycle is complex and usually requires a combination of field monitoring and modelling approaches (Weiler and McDonnell, 2004; National Research Council, 2008). Models are important tools for testing hypotheses, understanding hydrological processes and synthesizing experimental data...

  4. [Forest carbon cycle model: a review].

    Science.gov (United States)

    Wang, Ping

    2009-06-01

    Forest carbon cycle is one of the important items in the research of terrestrial carbon cycle, while carbon cycle model is an important means in studying the carbon cycle mechanisms of forest ecosystem and in estimating carbon fluxes. Based on the sum-up of main carbon cycle models, this paper classified the forest carbon cycle models into two categories, i.e., patch scale forest carbon cycle models and regional scale terrestrial carbon cycle models, with their features commented. The future development trend in the research of forest carbon cycle models in China was discussed.

  5. Hydrological modelling in forested systems | Science ...

    Science.gov (United States)

    This chapter provides a brief overview of forest hydrology modelling approaches for answering important global research and management questions. Many hundreds of hydrological models have been applied globally across multiple decades to represent and predict forest hydrological processes. The focus of this chapter is on process-based models and approaches, specifically 'forest hydrology models'; that is, physically based simulation tools that quantify compartments of the forest hydrological cycle. Physically based models can be considered those that describe the conservation of mass, momentum and/or energy. The purpose of this chapter is to provide a brief overview of forest hydrology modeling approaches for answering important global research and management questions. The focus of this chapter is on process-based models and approaches, specifically “forest hydrology models”, i.e., physically-based simulation tools that quantify compartments of the forest hydrological cycle.

  6. Wood decay fungi of subalpine conifer forests

    Science.gov (United States)

    Jessie A. Glaeser; Kevin T. Smith

    2016-01-01

    One of the fundamental skills needed for hazard tree assessment is the evaluation of decay. This may be a difficult task as we usually only use external symptoms (wounds, basal swellings, decayed branch stubs), signs (mushrooms, fungal crusts or brackets) or mechanical/indirect sampling methods (drilling, electrical or sonic resistance) to estimate the amount of sound...

  7. Hydro-geochemical modeling of subalpine urbanized area: geochemical characterization of the shallow and deep aquifers of the urban district of Como (first results).

    Science.gov (United States)

    Terrana, Silvia; Brunamonte, Fabio; Frascoli, Francesca; Ferrario, Maria Francesca; Michetti, Alessandro Maria; Pozzi, Andrea; Gambillara, Roberto; Binda, Gilberto

    2016-04-01

    One of the greatest environmental and social-economics threats is climate change. This topic, in the next few years, will have a significant impact on the availability of water resources of many regions. This is compounded by the strong anthropization of water systems that shows an intensification of conflicts for water resource exploitation. Therefore, it is necessary a sustainable manage of natural resources thorough knowledge of the hosting territories. The development of investigation and data processing methods are essential to reduce costs for the suitable use and protection of resources. Identify a sample area for testing the best approach is crucial. This research aims to find a valid methodology for the characterization, modeling and management of subalpine urban aquifers, and the urban district of Como appears perfect. The city of Como is located at the southern end of the western sector of Lake Como (N Italy). It is a coastal town, placed on a small alluvial plain, therefore in close communication with the lake. The plain is drained by two streams, which are presently artificially buried, and have an underground flow path in the urban section till the mouth. This city area, so, is suitable for this project as it is intensely urbanized, its dimensions is not too extensive and it is characterized by two aquifers very important and little known. These are a shallow aquifer and a deep aquifer, which are important not only for any water supply, but also for the stability of the ground subsidence in the city. This research is also the opportunity to work in a particular well-known area with high scientific significance; however, there is complete absence of information regarding the deep aquifer. Great importance has also the chosen and used of the more powerful open source software for this type of area, such as PHREEQC, EnvironInsite, PHREEQE etc., used for geological and geochemical data processing. The main goal of this preliminary work is the

  8. Modelling radiocesium fluxes in forest ecosystems

    International Nuclear Information System (INIS)

    Shaw, G.; Kliashtorin, A.; Mamikhin, S.; Shcheglov, A.; Rafferty, B.; Dvornik, A.; Zhuchenko, T.; Kuchma, N.

    1996-01-01

    Monitoring of radiocesium inventories and fluxes has been carried out in forest ecosystems in Ukraine, Belarus and Ireland to determine distributions and rates of migration. This information has been used to construct and calibrate mathematical models which are being used to predict the likely longevity of contamination of forests and forest products such as timber following the Chernobyl accident

  9. Growth responses of subalpine fir to climatic variability in the Pacific Northwest

    Science.gov (United States)

    Peterson, D.W.; Peterson, D.L.; Ettl, Gregory J.

    2002-01-01

    We studied regional variation in growth-limiting factors and responses to climatic variability in subalpine forests by analyzing growth patterns for 28 tree-ring growth chronologies from subalpine fir (Abies lasiocarpa (Hook.) Nutt.) stands in the Cascade and Olympic Mountains (Washington and Oregon, U.S.A.). Factor analysis identified four distinct time series of common growth patterns; the dominant growth pattern at any site varied with annual precipitation and temperature (elevation). Throughout much of the region, growth is negatively correlated with winter precipitation and spring snowpack depth, indicating that growth is limited primarily by short growing seasons. On the driest and warmest sites, growth is negatively correlated with previous summer temperature, suggesting that low summer soil moisture limits growth. Growth patterns in two regions were sensitive to climatic variability associated with the Pacific Decadal Oscillation, apparently responding to low-frequency variation in spring snowpack and summer soil moisture (one negatively, one positively). This regional-scale analysis shows that subalpine fir growth in the Cascades and Olympics is limited by different climatic factors in different subregional climates. Climatea??growth relationships are similar to those for a co-occurring species, mountain hemlock (Tsuga mertensiana (Bong.) Carri??re), suggesting broad biogeographic patterns of response to climatic variability and change by subalpine forest ecosystems in the Pacific Northwest.

  10. An economic model of international wood supply, forest stock and forest area change

    Science.gov (United States)

    James A. Turner; Joseph Buongiorno; Shushuai Zhu

    2006-01-01

    Wood supply, the link between roundwood removals and forest resources, is an important component of forest sector models. This paper develops a model of international wood supply within the structure of the spatial equilibrium Global Forest Products Model. The wood supply model determines, for each country, the annual forest harvest, the annual change of forest stock...

  11. The Effect of Re-Planting Trees on Soil Microbial Communities in a Wildfire-Induced Subalpine Grassland

    Directory of Open Access Journals (Sweden)

    Ed-Haun Chang

    2017-10-01

    Full Text Available Wildfire often causes tremendous changes in ecosystems, particularly in subalpine and alpine areas, which are vulnerable due to severe climate conditions such as cold temperature and strong wind. This study aimed to clarify the effect of tree re-planting on ecosystem services such as the soil microbial community after several decades. We compared the re-planted forest and grassland with the mature forest as a reference in terms of soil microbial biomass C and N (Cmic and Nmic, enzyme activities, phospholipid fatty acids (PLFA composition, and denaturing gradient gel electrophoresis (DGGE. The Cmic and Nmic did not differ among the grassland, re-planted forest and mature forest soil; however, ratios of Cmic/Corg and Nmic/Ntot decreased from the grassland to re-planted forest and mature forest soil. The total PLFAs and those attributed to bacteria and Gram-positive and Gram-negative bacteria did not differ between the re-planted forest and grassland soil. Principle component analysis of the PLFA content separated the grassland from re-planted forest and mature forest soil. Similarly, DGGE analysis revealed changes in both bacterial and fungal community structures with changes in vegetation. Our results suggest that the microbial community structure changes with the re-planting of trees after a fire event in this subalpine area. Recovery of the soil microbial community to the original state in a fire-damaged site in a subalpine area may require decades, even under a re-planted forest.

  12. Stand Composition, Tree Proximity and Size Have Minimal Effects on Leaf Function of Coexisting Aspen and Subalpine Fir

    Science.gov (United States)

    Rhodes, Aaron C.; Barney, Trevor; St. Clair, Samuel B.

    2016-01-01

    Forest structural heterogeneity due to species composition, spatial relationships and tree size are widely studied patterns in forest systems, but their impacts on tree function are not as well documented. The objective of this study was to examine how stand composition, tree proximity relationships and tree size influence the leaf functional traits of aspen, an early successional species, and subalpine fir, a climax species. We measured foliar nutrients, nonstructural carbohydrates (aspen only), defense chemistry and xylem water potential of aspen and subalpine fir trees in three size classes growing in close proximity or independently from other trees under three stand conditions: aspen dominant, aspen-conifer mixed, and conifer dominant stands. Close proximity of subalpine fir to aspen reduced aspen’s storage of starch in foliar tissue by 17% suggesting that competition between these species may have small effects on carbon metabolism in aspen leaves. Simple sugar (glucose + sucrose) concentrations in aspen leaves were slightly higher in larger aspen trees than smaller trees. However, no differences were found in stem water potential, foliar concentrations of nitrogen, phosphorus, or secondary defense chemicals of aspen or subalpine fir across the gradients of stand composition, tree proximity or tree size. These results suggest that mechanisms of coexistence allow both aspen and subalpine fir to maintain leaf function across a wide range of stand structural characteristics. For aspen, resource sharing through its clonal root system and high resource storage capacity may partially contribute to its functional stability in mixed aspen-conifer stands. PMID:27124496

  13. Stand Composition, Tree Proximity and Size Have Minimal Effects on Leaf Function of Coexisting Aspen and Subalpine Fir.

    Directory of Open Access Journals (Sweden)

    Aaron C Rhodes

    Full Text Available Forest structural heterogeneity due to species composition, spatial relationships and tree size are widely studied patterns in forest systems, but their impacts on tree function are not as well documented. The objective of this study was to examine how stand composition, tree proximity relationships and tree size influence the leaf functional traits of aspen, an early successional species, and subalpine fir, a climax species. We measured foliar nutrients, nonstructural carbohydrates (aspen only, defense chemistry and xylem water potential of aspen and subalpine fir trees in three size classes growing in close proximity or independently from other trees under three stand conditions: aspen dominant, aspen-conifer mixed, and conifer dominant stands. Close proximity of subalpine fir to aspen reduced aspen's storage of starch in foliar tissue by 17% suggesting that competition between these species may have small effects on carbon metabolism in aspen leaves. Simple sugar (glucose + sucrose concentrations in aspen leaves were slightly higher in larger aspen trees than smaller trees. However, no differences were found in stem water potential, foliar concentrations of nitrogen, phosphorus, or secondary defense chemicals of aspen or subalpine fir across the gradients of stand composition, tree proximity or tree size. These results suggest that mechanisms of coexistence allow both aspen and subalpine fir to maintain leaf function across a wide range of stand structural characteristics. For aspen, resource sharing through its clonal root system and high resource storage capacity may partially contribute to its functional stability in mixed aspen-conifer stands.

  14. Combinatorial Optimization in Forest Ecosystem Management Modeling

    OpenAIRE

    BAŞKENT, Emin Zeki

    2001-01-01

    Modeling forest management activities has been tackled by scientists over the last two decades. Both simulation and optimization techniques have been used in solving forest management planning problems. With the introduction of ecosystems management that focuses on the sustainable production and maintenance of ecological, social and economical values, neither approach provided a credible solution technique to help design the complex structure of forest management activities. Alternative to th...

  15. Modeling Forest Structure and Vascular Plant Diversity in Piedmont Forests

    Science.gov (United States)

    Hakkenberg, C.

    2014-12-01

    When the interacting stressors of climate change and land cover/land use change (LCLUC) overwhelm ecosystem resilience to environmental and climatic variability, forest ecosystems are at increased risk of regime shifts and hyperdynamism in process rates. To meet the growing range of novel biotic and environmental stressors on human-impacted ecosystems, the maintenance of taxonomic diversity and functional redundancy in metacommunities has been proposed as a risk spreading measure ensuring that species critical to landscape ecosystem functioning are available for recruitment as local systems respond to novel conditions. This research is the first in a multi-part study to establish a dynamic, predictive model of the spatio-temporal dynamics of vascular plant diversity in North Carolina Piedmont mixed forests using remotely sensed data inputs. While remote sensing technologies are optimally suited to monitor LCLUC over large areas, direct approaches to the remote measurement of plant diversity remain a challenge. This study tests the efficacy of predicting indices of vascular plant diversity using remotely derived measures of forest structural heterogeneity from aerial LiDAR and high spatial resolution broadband optical imagery in addition to derived topo-environmental variables. Diversity distribution modelling of this sort is predicated upon the idea that environmental filtering of dispersing species help define fine-scale (permeable) environmental envelopes within which biotic structural and compositional factors drive competitive interactions that, in addition to background stochasticity, determine fine-scale alpha diversity. Results reveal that over a range of Piedmont forest communities, increasing structural complexity is positively correlated with measures of plant diversity, though the nature of this relationship varies by environmental conditions and community type. The diversity distribution model is parameterized and cross-validated using three high

  16. Modeling landowner behavior regarding forest certification

    Science.gov (United States)

    David C. Mercker; Donald G. Hodges

    2008-01-01

    Nonindustrial private forest owners in western Tennessee were surveyed to assess their awareness, acceptance, and perceived benefits of forest certification. More than 80 percent of the landowners indicated a willingness to consider certification for their lands. A model was created to explain landowner behavior regarding their willingness to consider certification....

  17. Dynamic Properties of a Forest Fire Model

    Directory of Open Access Journals (Sweden)

    Na Min

    2012-01-01

    Full Text Available The reaction-diffusion equations have been widely used in physics, chemistry, and other areas. Forest fire can also be described by such equations. We here propose a fighting forest fire model. By using the normal form approach theory and center manifold theory, we analyze the stability of the trivial solution and Hopf bifurcation of this model. Finally, we give the numerical simulations to illustrate the effectiveness of our results.

  18. Review of forest landscape models: types, methods, development and applications

    Science.gov (United States)

    Weimin Xi; Robert N. Coulson; Andrew G. Birt; Zong-Bo Shang; John D. Waldron; Charles W. Lafon; David M. Cairns; Maria D. Tchakerian; Kier D. Klepzig

    2009-01-01

    Forest landscape models simulate forest change through time using spatially referenced data across a broad spatial scale (i.e. landscape scale) generally larger than a single forest stand. Spatial interactions between forest stands are a key component of such models. These models can incorporate other spatio-temporal processes such as...

  19. Biogeochemical impacts of wildfires over four millennia in a Rocky Mountain subalpine watershed.

    Science.gov (United States)

    Dunnette, Paul V; Higuera, Philip E; McLauchlan, Kendra K; Derr, Kelly M; Briles, Christy E; Keefe, Margaret H

    2014-08-01

    Wildfires can significantly alter forest carbon (C) storage and nitrogen (N) availability, but the long-term biogeochemical legacy of wildfires is poorly understood. We obtained a lake-sediment record of fire and biogeochemistry from a subalpine forest in Colorado, USA, to examine the nature, magnitude, and duration of decadal-scale, fire-induced ecosystem change over the past c. 4250 yr. The high-resolution record contained 34 fires, including 13 high-severity events within the watershed. High-severity fires were followed by increased sedimentary N stable isotope ratios (δ15N) and bulk density, and decreased C and N concentrations--reflecting forest floor destruction, terrestrial C and N losses, and erosion. Sustained low sediment C : N c. 20-50 yr post-fire indicates reduced terrestrial organic matter subsidies to the lake. Low sedimentary δ15N c. 50-70 yr post-fire, coincident with C and N recovery, suggests diminishing terrestrial N availability during stand development. The magnitude of post-fire changes generally scaled directly with inferred fire severity. Our results support modern studies of forest successional C and N accumulation and indicate pronounced, long-lasting biogeochemical impacts of wildfires in subalpine forests. However, even repeated high-severity fires over millennia probably did not deplete C or N stocks, because centuries between high-severity fires allowed for sufficient biomass recovery. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  20. A multi-proxy record of hydroclimate, vegetation, fire, and post-settlement impacts for a subalpine plateau, Central Rocky Mountains U.S.A

    Science.gov (United States)

    Anderson, Lesleigh; Brunelle, Andrea; Thompson, Robert S.

    2015-01-01

    Apparent changes in vegetation distribution, fire, and other disturbance regimes throughout western North America have prompted investigations of the relative importance of human activities and climate change as potential causal mechanisms. Assessing the effects of Euro-American settlement is difficult because climate changes occur on multi-decadal to centennial time scales and require longer time perspectives than historic observations can provide. Here, we report vegetation and environmental changes over the past ~13,000 years as recorded in a sediment record from Bison Lake, a subalpine lake on a high plateau in northwestern Colorado. Results are based on multiple independent proxies, which include pollen, charcoal, and elemental geochemistry, and are compared with previously reported interpretations of hydroclimatic changes from oxygen isotope ratios. The pollen data indicate a slowly changing vegetation sequence from sagebrush steppe during the late glacial to coniferous forest through the late Holocene. The most dramatic vegetation changes of the Holocene occurred during the ‘Medieval Climate Anomaly’ (MCA) and ‘Little Ice Age’ (LIA) with rapid replacement of conifer forest by grassland followed by an equally rapid return to conifer forest. Late Holocene vegetation responses are mirrored by changes in fire, lake biological productivity, and watershed erosion. These combined records indicate that subsequent disturbance related to Euro-American settlement, although perhaps significant, had acted upon a landscape that was already responding to MCA-LIA hydroclimatic change. Results document both rapid and long-term subalpine grassland ecosystem dynamics driven by agents of change that can be anticipated in the future and simulated by ecosystem models.

  1. Measuring and modelling forest transpiration

    Czech Academy of Sciences Publication Activity Database

    Šír, Miloslav; Čermák, J.; Naděždina, N.; Pražák, Josef; Tesař, Miroslav

    2008-01-01

    Roč. 4, - (2008), č. 012050 ISSN 1755-1315. [Conference of the Danubian Countries on the Hydrological Forecasting and Hydrological Bases of Water Management /24./. Bled, 02.06.2008-04.06.2008] R&D Projects: GA ČR GA205/06/0375; GA ČR GA205/08/1174; GA ČR GA526/08/1016; GA MŠk MEB0808114; GA MŽP(CZ) SP/1A6/151/07; GA AV ČR 1QS200420562 Institutional research plan: CEZ:AV0Z20600510; CEZ:AV0Z20760514 Keywords : plant transpiration * SAP flow * floodplain forest Subject RIV: DA - Hydrology ; Limnology

  2. Streamflow response to future land-cover change at a headwaters catchment spanning the alpine-subalpine transition on the Colorado Front Range

    Science.gov (United States)

    Barnhart, T. B.; Vukomanovic, J.; Bourgeron, P.; Molotch, N. P.

    2017-12-01

    Land-cover change at the alpine-subalpine interface has the potential to change the water balance of mountainous, snow-dominated catchments due to the influence of vegetation on blowing snow, effective precipitation, evapotranspiration, and other processes. Understanding how land-cover change will impact water resources in snow-dominated regions is of critical importance as these locations produce a disproportionate amount of runoff relative to their land area. We coupled the LANdscape DIsturbance and Succession (LANDIS-II) model with a spatially explicit, physics-based, watershed process model, the Regional Hydro-Ecologic Simulation System (RHESSys), to simulate land-cover change and its impact on the water balance in a 6.6 km­2 headwater catchment that spans the alpine-subalpine transition on the Colorado Front Range. We simulated two potential futures of air temperature warming (+4 °C/century) to 2100: a) increased precipitation (+15%, MP) and b) decreased precipitation (-15%, LP). As the LANDIS-II model simulates forest succession in a stochastic manner, we use three LANDIS-II model runs each for the MP and LP future forcing conditions. For both MP and LP, the RHESSys forcing data set was updated to reflect the changes in precipitation and temperature used to generate the land-cover futures. Forest cover in the catchment increased from 72% in 2000 to 84% and 83% in 2050 and to 95% and 92% in 2100 for MP and LP, respectively. Somewhat surprisingly, this increase in forest cover led to mean increases in streamflow production of 9% for MP and 3% for LP in 2050. In 2100, mean streamflow production increased by 15% and 6% for the MP and LP scenarios, respectively. This is likely due to increases in effective precipitation as the catchment forested and blowing snow decreased. Indeed, catchment effective precipitation increased from 94% in 2000 to 97% and 99% in 2050 and 2100, respectively, for both MP and LP conditions. This result counters previous work as runoff

  3. Ecological modeling for forest management in the Shawnee National Forest

    Science.gov (United States)

    Richard G. Thurau; J.F. Fralish; S. Hupe; B. Fitch; A.D. Carver

    2008-01-01

    Land managers of the Shawnee National Forest in southern Illinois are challenged to meet the needs of a diverse populace of stakeholders. By classifying National Forest holdings into management units, U.S. Forest Service personnel can spatially allocate resources and services to meet local management objectives. Ecological Classification Systems predict ecological site...

  4. Forest-succession models and their ecological and management implications

    Energy Technology Data Exchange (ETDEWEB)

    West, D.; Smith, T.M.; Weinstein, D.A.; Shugart, H.H.

    1981-01-01

    Computer models of forest succession have been developed to an extent that allows their use as a tool for predicting forest ecosystem behavior over long periods of time. This paper outlines the use of one approach to forest succession modeling for a variety of problems including: (1) determining the effect of climate change on forests; (2) integrating information on wildlife habitat changes with the changes in forest structure associated with timber management; (3) assessing the potential effect of air pollutants on forest dynamics; and (4) determining the theoretical importance of disturbance on forest community diversity and function.

  5. Lab and Field Warming Similarly Advance Germination Date and Limit Germination Rate for High and Low Elevation Provenances of Two Widespread Subalpine Conifers

    Directory of Open Access Journals (Sweden)

    Lara M. Kueppers

    2017-11-01

    Full Text Available Accurately predicting upslope shifts in subalpine tree ranges with warming requires understanding how future forest populations will be affected by climate change, as these are the seed sources for new tree line and alpine populations. Early life history stages are particularly sensitive to climate and are also influenced by genetic variation among populations. We tested the climate sensitivity of germination and initial development for two widely distributed subalpine conifers, using controlled-environment growth chambers with one temperature regime from subalpine forest in the Colorado Rocky Mountains and one 5 °C warmer, and two soil moisture levels. We tracked germination rate and timing, rate of seedling development, and seedling morphology for two seed provenances separated by ~300 m elevation. Warming advanced germination timing and initial seedling development by a total of ~2 weeks, advances comparable to mean differences between provenances. Advances were similar for both provenances and species; however, warming reduced the overall germination rate, as did low soil moisture, only for Picea engelmannii. A three-year field warming and watering experiment planted with the same species and provenances yielded responses qualitatively consistent with the lab trials. Together these experiments indicate that in a warmer, drier climate, P. engelmannii germination, and thus regeneration, could decline, which could lead to declining subalpine forest populations, while Pinus flexilis forest populations could remain robust as a seed source for upslope range shifts.

  6. Potentials and limitations of using large-scale forest inventory data for evaluating forest succession models

    NARCIS (Netherlands)

    Didion, M.P.; Kupferschmid, A.D.; Lexer, M.J.; Rammer, W.; Seidl, R.; Bugmann, H.

    2009-01-01

    Forest gap models have been applied widely to examine forest development under natural conditions and to investigate the effect of climate change on forest succession. Due to the complexity and parameter requirements of such models a rigorous evaluation is required to build confidence in the

  7. Similarity of nutrient uptake and root dimensions of Engelmann spruce and subalpine fir at two contrasting sites in Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Yanai, R; McFarlane, K; Lucash, M; Kulpa, S; Wood, D

    2009-10-09

    Nutrient uptake capacity is an important parameter in modeling nutrient uptake by plants. Researchers commonly assume that uptake capacity measured for a species can be used across sites. We tested this assumption by measuring the nutrient uptake capacity of intact roots of Engelmann spruce (Picea engelmanni Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) at Loch Vale Watershed and Fraser Experimental Forest in the Rocky Mountains of central Colorado. Roots still attached to the tree were exposed to one of three concentrations of nutrient solutions for time periods ranging from 1 to 96 hours, and solutions were analyzed for ammonium, nitrate, calcium, magnesium, and potassium. Surprisingly, the two species were indistinguishable in nutrient uptake within site for all nutrients (P > 0.25), but uptake rates differed by site. In general, nutrient uptake was higher at Fraser (P = 0.01, 0.15, 0.03, 0.18 for NH{sub 4}{sup +}, NO{sub 3}{sup -}, Ca{sup 2+}, and K{sup +}, respectively), which is west of the Continental Divide and has lower atmospheric deposition of N than Loch Vale. Mean uptake rates by site for ambient solution concentrations were 0.12 {micro}mol NH{sub 4}{sup +} g{sub fwt}{sup -1} h{sup -1}, 0.02 {micro}mol NO{sub 3}{sup -} g{sub fwt}{sup -1}, 0.21 {micro}mol Ca{sup 2+} g{sub fwt}{sup -1} h{sup -1}, and 0.01 {micro}mol Mg{sup 2+} g{sub fwt}{sup -1} h{sup -1} at Loch Vale, and 0.21 {micro}mol NH{sub 4}{sup +} f{sub fwt}{sup -1}h{sup -1}, 0.04 {micro}mol NO{sub 3}{sup -} g{sub fwt}{sup -1} h{sup -1}, 0.51 {micro}mol Ca{sup 2+}g{sub fwt}{sup -1}h{sup -1}, and 0.07 {micro}mol Mg{sup 2+} f{sub fwt}{sup -1}h{sup -1} at Fraser. The importance of site conditions in determining uptake capacity should not be overlooked when parameterizing nutrient uptake models. We also characterized the root morphology of these two species and compared them to other tree species we have measured at various sites in the northeastern USA. Engelman spruce and subalpine fir

  8. Exploring component-based approaches in forest landscape modeling

    Science.gov (United States)

    H. S. He; D. R. Larsen; D. J. Mladenoff

    2002-01-01

    Forest management issues are increasingly required to be addressed in a spatial context, which has led to the development of spatially explicit forest landscape models. The numerous processes, complex spatial interactions, and diverse applications in spatial modeling make the development of forest landscape models difficult for any single research group. New...

  9. Modelling tropical forests response to logging

    Science.gov (United States)

    Cazzolla Gatti, Roberto; Di Paola, Arianna; Valentini, Riccardo; Paparella, Francesco

    2013-04-01

    Tropical rainforests are among the most threatened ecosystems by large-scale fragmentation due to human activity such as heavy logging and agricultural clearance. Although, they provide crucial ecosystem goods and services, such as sequestering carbon from the atmosphere, protecting watersheds and conserving biodiversity. In several countries forest resource extraction has experienced a shift from clearcutting to selective logging to maintain a significant forest cover and understock of living biomass. However the knowledge on the short and long-term effects of removing selected species in tropical rainforest are scarce and need to be further investigated. One of the main effects of selective logging on forest dynamics seems to be the local disturbance which involve the invasion of open space by weed, vines and climbers at the expense of the late-successional state cenosis. We present a simple deterministic model that describes the dynamics of tropical rainforest subject to selective logging to understand how and why weeds displace native species. We argue that the selective removal of tallest tropical trees carries out gaps of light that allow weeds, vines and climbers to prevail on native species, inhibiting the possibility of recovery of the original vegetation. Our results show that different regime shifts may occur depending on the type of forest management adopted. This hypothesis is supported by a dataset of trees height and weed/vines cover that we collected from 9 plots located in Central and West Africa both in untouched and managed areas.

  10. Comparative seed germination traits in alpine and subalpine grasslands: higher elevations are associated with warmer germination temperatures.

    Science.gov (United States)

    Fernández-Pascual, E; Jiménez-Alfaro, B; Bueno, Á

    2017-01-01

    Seed germination traits in alpine grasslands are poorly understood, despite the sensitivity of these communities to climate change. We hypothesise that germination traits predict species occurrence along the alpine-subalpine elevation gradient. Phylogenetic comparative analyses were performed using fresh seeds of 22 species from alpine and subalpine grasslands (1600-2400 m) of the Cantabrian Mountains, Spain (43° N, 5° W). Laboratory experiments were conducted to characterise germinability, optimum germination temperature and effect of cold and warm stratification on dormancy breaking. Variability in these traits was reduced by phylogenetic principal component analysis (phyl.PCA). Phylogenetic generalised least squares regression (PGLS) was used to fit a model in which species average elevation was predicted from their position on the PCA axes. Most subalpine species germinated in snow-like conditions, whereas most alpine species needed accumulation of warm temperatures. Phylogenetic signal was low. PCA1 ordered species according to overall germinability, whilst PCA2 ordered them according to preference for warm or cold germination. PCA2 significantly predicted species occurrence in the alpine-subalpine gradient, as higher elevation species tended to have warmer germination preferences. Our results show that germination traits in high-mountain grasslands are closely linked to the alpine-subalpine gradient. Alpine species, especially those from stripped and wind-edge communities, prefer warmer germination niches, suggesting that summer emergence prevents frost damage during seedling establishment. In contrast, alpine snowfield and subalpine grassland plants have cold germination niches, indicating that winter emergence may occur under snow to avoid drought stress. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

  11. DRAINMOD-FOREST: Integrated modeling of hydrology, soil carbon and nitrogen dynamics, and plant growth for drained forests

    Science.gov (United States)

    Shiying Tian; Mohamed A. Youssef; R. Wayne Skaggs; Devendra M. Amatya; G.M. Chescheir

    2012-01-01

    We present a hybrid and stand-level forest ecosystem model, DRAINMOD-FOREST, for simulating the hydrology, carbon (C) and nitrogen (N) dynamics, and tree growth for drained forest lands under common silvicultural practices. The model was developed by linking DRAINMOD, the hydrological model, and DRAINMOD-N II, the soil C and N dynamics model, to a forest growth model,...

  12. Supply chain modeling of forest fuel

    International Nuclear Information System (INIS)

    Gunnarsson, Helene; Lundgren, Jan T.; Roennqvist, Mikael

    2001-04-01

    We study the problem of deciding when and where forest residues are to be converted into forest fuel, and how the residues are to be transported and stored in order to satisfy demand at heating plants. Decisions also include whether or not additional harvest areas and saw-mills are to be contracted. In addition, we consider the flow of products from saw-mills and import harbors, and address the question about which terminals to use. The planning horizon is one year and monthly time periods are considered. The supply chain problem is formulated as a large mixed integer linear programming model. In order to obtain solutions within reasonable time we have developed a heuristic solution approach. Computational results from a large Swedish supplying entrepreneur are reported

  13. ORGEST: Regional guidelines and silvicultural models for sustainable forest management

    Energy Technology Data Exchange (ETDEWEB)

    Piqué, Míriam; Vericat, Pau; Beltrán, Mario

    2017-11-01

    Aim of the study: To develop regional guidelines for sustainable forest management. Area of the study: Forests of Catalonia (NE Spain). Material and methods: The process of developing the forest management guidelines (FMG) started by establishing a thorough classification of forest types at stand level. This classification hinges on two attributes: tree species composition and site quality based on ecological variables, which together determine potential productivity. From there, the management guidelines establish certain objectives and silvicultural models for each forest type. The forest type classifications, like the silvicultural models, were produced using both existing and newly-built growth models based on data from the National Forest Inventory (NFI) and expert knowledge. The effort involved over 20 expert working groups in order to better integrate the expertise and vision of different sectorial agents. Main results: The FMG consist in quantitative silvicultural models that include typical silvicultural variables, technical descriptions of treatments and codes of good practice. Guidelines now cover almost all forest types in Catalonia (spanning up to 90% of the Catalan forest area). Different silvicultural models have been developed for pure and mixed stands, different site quality classes (2–3 classes per species), and even- and multi-aged stands. Research highlights: FMG: i) orient the management of private and public forests, (ii) provide a technical scaffold for efficient allocation/investment of public subsidies in forest management, and (iii) bridge forest planning instruments at regional (strategic-tactical) and stand (operational) level.

  14. Global sensitivity analysis of DRAINMOD-FOREST, an integrated forest ecosystem model

    Science.gov (United States)

    Shiying Tian; Mohamed A. Youssef; Devendra M. Amatya; Eric D. Vance

    2014-01-01

    Global sensitivity analysis is a useful tool to understand process-based ecosystem models by identifying key parameters and processes controlling model predictions. This study reported a comprehensive global sensitivity analysis for DRAINMOD-FOREST, an integrated model for simulating water, carbon (C), and nitrogen (N) cycles and plant growth in lowland forests. The...

  15. Combining fire and erosion modeling to target forest management activities

    Science.gov (United States)

    William J. Elliot; Mary Ellen Miller; Nic Enstice

    2015-01-01

    Forests deliver a number of important ecosystem services including clean water. When forests are disturbed by wildfire, the timing, quantity and quality of runoff are altered. A modeling study was carried out in a forested watershed in California to determine the risk of wildfire, and the potential post-fire sediment delivery from approximately 6-ha hillslope polygons...

  16. Targeting forest management through fire and erosion modeling

    Science.gov (United States)

    William J. Elliot; Mary Ellen Miller; Nic Enstice

    2016-01-01

    Forests deliver a number of important ecosystem services, including clean water. When forests are disturbed by wildfire, the timing, quantity and quality of runoff are altered. A modelling study was conducted in a forested watershed in California, USA, to determine the risk of wildfire, and the potential post-fire sediment delivery from ~4-ha hillslope polygons within...

  17. Modeling erosion from forest roads with WEPP

    Science.gov (United States)

    J. McFero Grace

    2007-01-01

    Forest roads can be major sources of soil erosion from forest watersheds. Sediments from forest roads are a concern due to their potential delivery to stream systems resulting in degradation of water quality. The Water Erosion Prediction Project (WEPP) was used to predict erosion from forest road components under different management practices. WEPP estimates are...

  18. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes

    Science.gov (United States)

    Eagles-Smith, Collin A.; Herring, Garth; Johnson, Branden L.; Graw, Rick

    2016-01-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

  19. Evaluating the long-term management of introduced ungulates to protect the palila, an endangered bird, and its criticial habitat in subalpine forest of Mauna Kea, Hawai'i

    Science.gov (United States)

    Banko, Paul C.; Hess, Steven C.; Scowcroft, Paul G.; Farmer, Chris; Jacobi, James D.; Stephens, Robert M.; Camp, Richard J.; Leonard, David L.; Brinck, Kevin W.; Juvik, J.O.; Juvik, S. P.

    2014-01-01

    Under the multiple-use paradigm, conflicts may arise when protection of an endangered species must compete with other management objectives. To resolve such a conflict in the Critical Habitat of the endangered Hawaiian honeycreeper, palila (Loxioides bailleui), federal courts ordered the eradication of introduced ungulates responsible for damaging the māmane (Sophora chrysophylla) forest on which palila depend. During 1980–2011, a total of 18,130 sheep (Ovis aries and O. gmelini musimon) and 310 goats (Capra hircus) were removed from Palila Critical Habitat (PCH) primarily by public hunters (54%) and secondarily by aerial shooting. Nevertheless, our analysis indicates that ungulates have increased over time. Palila numbers have declined sharply since 2003 due to long-term habitat degradation by ungulates and drought. Although culling ungulate populations has allowed some habitat improvement, their complete removal is necessary for palila to recover, especially given the potential for continued drought. Introduced predators are being controlled to reduce palila mortality, māmane and other native trees are being planted to restore some areas, and fencing is being constructed to prevent ungulate immigration. Funds are recently available for more effective eradication efforts, which are urgently needed to eliminate browsing damage in PCH and protect the palila from extinction.

  20. Numerical modeling of the airflow around a forest edge using LiDAR-derived forest heigths

    DEFF Research Database (Denmark)

    Boudreault, Louis-Etienne; Dellwik, Ebba; Bechmann, Andreas

    A 3D methodology to quantify the effect of forests on the mean wind flow field is presented. The methodology is based on the treatment of forest raw data of light detection and ranging (LiDAR) scans, and a computational fluid dynamics (CFD) method based on a Reynolds-averaged Navier-Stokes (Ra......NS) approach using the k−e turbulence model with a corresponding canopy model. The example site investigated is a forest edge located on the Falster island in Denmark, where a measurement campaign was conducted. The LiDAR scans are used in order to obtain the forest heights, which served as input...

  1. The Impact of Forest Density on Forest Height Inversion Modeling from Polarimetric InSAR Data

    Directory of Open Access Journals (Sweden)

    Changcheng Wang

    2016-03-01

    Full Text Available Forest height is of great significance in analyzing the carbon cycle on a global or a local scale and in reconstructing the accurate forest underlying terrain. Major algorithms for estimating forest height, such as the three-stage inversion process, are depending on the random-volume-over-ground (RVoG model. However, the RVoG model is characterized by a lot of parameters, which influence its applicability in forest height retrieval. Forest density, as an important biophysical parameter, is one of those main influencing factors. However, its influence to the RVoG model has been ignored in relating researches. For this paper, we study the applicability of the RVoG model in forest height retrieval with different forest densities, using the simulated and real Polarimetric Interferometric SAR data. P-band ESAR datasets of the European Space Agency (ESA BioSAR 2008 campaign were selected for experiments. The test site was located in Krycklan River catchment in Northern Sweden. The experimental results show that the forest density clearly affects the inversion accuracy of forest height and ground phase. For the four selected forest stands, with the density increasing from 633 to 1827 stems/Ha, the RMSEs of inversion decrease from 4.6 m to 3.1 m. The RVoG model is not quite applicable for forest height retrieval especially in sparsely vegetated areas. We conclude that the forest stand density is positively related to the estimation accuracy of the ground phase, but negatively correlates to the ground-to-volume scattering ratio.

  2. Using advanced surface complexation models for modelling soil chemistry under forests: Solling forest, Germany

    International Nuclear Information System (INIS)

    Bonten, Luc T.C.; Groenenberg, Jan E.; Meesenburg, Henning; Vries, Wim de

    2011-01-01

    Various dynamic soil chemistry models have been developed to gain insight into impacts of atmospheric deposition of sulphur, nitrogen and other elements on soil and soil solution chemistry. Sorption parameters for anions and cations are generally calibrated for each site, which hampers extrapolation in space and time. On the other hand, recently developed surface complexation models (SCMs) have been successful in predicting ion sorption for static systems using generic parameter sets. This study reports the inclusion of an assemblage of these SCMs in the dynamic soil chemistry model SMARTml and applies this model to a spruce forest site in Solling Germany. Parameters for SCMs were taken from generic datasets and not calibrated. Nevertheless, modelling results for major elements matched observations well. Further, trace metals were included in the model, also using the existing framework of SCMs. The model predicted sorption for most trace elements well. - Highlights: → Surface complexation models can be well applied in field studies. → Soil chemistry under a forest site is adequately modelled using generic parameters. → The model is easily extended with extra elements within the existing framework. → Surface complexation models can show the linkages between major soil chemistry and trace element behaviour. - Surface complexation models with generic parameters make calibration of sorption superfluous in dynamic modelling of deposition impacts on soil chemistry under nature areas.

  3. Model-based assessments of climate change effects on forests

    Energy Technology Data Exchange (ETDEWEB)

    Loehle, C.; LeBlanc, D.C. [Argonne National Lab., IL (United States)]|[Ball State Univ., Muncie, IN (United States)

    1995-06-01

    The potential effects of climate change on forests are of increasing concern. A number of studies based on forest simulation models predict substantial alteration of forest composition, forest dieback, or even loss of forest cover in response to increased temperatures associated with increasing atmospheric carbon dioxide concentrations. However, the structure of these computer models may cause them to overemphasize the role of climate in controlling tree growth and mortality. Model functions that represent the influence of climate on tree growth are based on the geographic range limits of a species, predicting maximal growth in the center of the range and zero growth (100% mortality) at the range limits and beyond. Many tree species can survive in climatic conditions outside their present range limits and can tolerate widely fluctuating climate regimes. Hence, there is reason to suspect that published projections of forest responses to climate change may exaggerate the direct impact of climate on tree growth and mortality. We propose that forest simulation models be reformulated with more realistic representations of growth responses to temperature, moisture, mortality and dispersal. We believe that only when these models more accurately reflect the physiological bases of the responses of tree species to climate variables can they be used to simulate responses of forests to rapid changes in climate. We argue that direct forest responses to climate change projected by such a reformulated model may be less traumatic and more gradual than those projected by current models.

  4. Forest owner representation of forest management and perception of resource efficiency: a structural equation modeling study

    Directory of Open Access Journals (Sweden)

    Andrej Ficko

    2015-03-01

    Full Text Available Underuse of nonindustrial private forests in developed countries has been interpreted mostly as a consequence of the prevailing noncommodity objectives of their owners. Recent empirical studies have indicated a correlation between the harvesting behavior of forest owners and the specific conceptualization of appropriate forest management described as "nonintervention" or "hands-off" management. We aimed to fill the huge gap in knowledge of social representations of forest management in Europe and are the first to be so rigorous in eliciting forest owner representations in Europe. We conducted 3099 telephone interviews with randomly selected forest owners in Slovenia, asking them whether they thought they managed their forest efficiently, what the possible reasons for underuse were, and what they understood by forest management. Building on social representations theory and applying a series of structural equation models, we tested the existence of three latent constructs of forest management and estimated whether and how much these constructs correlated to the perception of resource efficiency. Forest owners conceptualized forest management as a mixture of maintenance and ecosystem-centered and economics-centered management. None of the representations had a strong association with the perception of resource efficiency, nor could it be considered a factor preventing forest owners from cutting more. The underuse of wood resources was mostly because of biophysical constraints in the environment and not a deep-seated philosophical objection to harvesting. The difference between our findings and other empirical studies is primarily explained by historical differences in forestland ownership in different parts of Europe and the United States, the rising number of nonresidential owners, alternative lifestyle, and environmental protectionism, but also as a consequence of our high methodological rigor in testing the relationships between the constructs

  5. Fitting rainfall interception models to forest ecosystems of Mexico

    Science.gov (United States)

    Návar, José

    2017-05-01

    Models that accurately predict forest interception are essential both for water balance studies and for assessing watershed responses to changes in land use and the long-term climate variability. This paper compares the performance of four rainfall interception models-the sparse Gash (1995), Rutter et al. (1975), Liu (1997) and two new models (NvMxa and NvMxb)-using data from four spatially extensive, structurally diverse forest ecosystems in Mexico. Ninety-eight case studies measuring interception in tropical dry (25), arid/semi-arid (29), temperate (26), and tropical montane cloud forests (18) were compiled and analyzed. Coefficients derived from raw data or published statistical relationships were used as model input to evaluate multi-storm forest interception at the case study scale. On average empirical data showed that, tropical montane cloud, temperate, arid/semi-arid and tropical dry forests intercepted 14%, 18%, 22% and 26% of total precipitation, respectively. The models performed well in predicting interception, with mean deviations between measured and modeled interception as a function of total precipitation (ME) generally 0.66. Model fitting precision was dependent on the forest ecosystem. Arid/semi-arid forests exhibited the smallest, while tropical montane cloud forest displayed the largest ME deviations. Improved agreement between measured and modeled data requires modification of in-storm evaporation rate in the Liu; the canopy storage in the sparse Gash model; and the throughfall coefficient in the Rutter and the NvMx models. This research concludes on recommending the wide application of rainfall interception models with some caution as they provide mixed results. The extensive forest interception data source, the fitting and testing of four models, the introduction of a new model, and the availability of coefficient values for all four forest ecosystems are an important source of information and a benchmark for future investigations in this

  6. Evaluation of forest snow processes models (SnowMKIP2)

    Science.gov (United States)

    Nick Rutter; Richard Essery; John Pomeroy; Nuria Altimir; Kostas Andreadis; Ian Baker; Alan Barr; Paul Bartlett; Aaron Boone; Huiping Deng; Herve Douville; Emanuel Dutra; Kelly Elder; others

    2009-01-01

    Thirty-three snowpack models of varying complexity and purpose were evaluated across a wide range of hydrometeorological and forest canopy conditions at five Northern Hemisphere locations, for up to two winter snow seasons. Modeled estimates of snow water equivalent (SWE) or depth were compared to observations at forest and open sites at each location. Precipitation...

  7. A model to predict the sound reflection from forests

    NARCIS (Netherlands)

    Wunderli, J.M.; Salomons, E.M.

    2009-01-01

    A model is presented to predict the reflection of sound at forest edges. A single tree is modelled as a vertical cylinder. For the reflection at a cylinder an analytical solution is given based on the theory of scattering of spherical waves. The entire forest is represented by a line of cylinders

  8. LINKAGES: An Individual-based Forest Ecosystem Biogeochemistry Model

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This model product contains the source codes for version 1 of the individual-based forest ecosystem biogeochemistry model LINKAGES and two subsequent...

  9. LINKAGES: An Individual-based Forest Ecosystem Biogeochemistry Model

    Data.gov (United States)

    National Aeronautics and Space Administration — This model product contains the source codes for version 1 of the individual-based forest ecosystem biogeochemistry model LINKAGES and two subsequent versions as...

  10. Forests

    Science.gov (United States)

    Louis R. Iverson; Mark W. Schwartz

    1994-01-01

    Originally diminished by development, forests are coming back: forest biomass is accumulating. Forests are repositories for many threatened species. Even with increased standing timber, however, biodiversity is threatened by increased forest fragmentation and by exotic species.

  11. Modelling of 137Cs behaviour in forest ecosystems and prediction of its accumulation in forest products

    International Nuclear Information System (INIS)

    Spiridonov, S.I.; Fesenko, S.V.; Gontarenko, I.A.; Avila, R.

    2001-01-01

    A mathematical model of 137 Cs migration in forest ecosystem contaminated due to the Chernobyl accident presented, which describes the behaviour of this radionuclide in the forest litter-soil system, tress, and forest animals. The model's parameters for different types of forest ecosystems are estimated and model's adequacy is tested through the use of independent experimental data. The sensitivity of the model's output variables is analyzed to variations in the most significant parameters. The differences in the seasonal and mean annual dynamics of 137 Cs concentration in muscles of roe deers and mooses are shown to be defined by specific features of the diets of these animals and variations in 137 Cs content in the main diet components [ru

  12. Soil ecological interactions: comparisons between tropical and subalpine forests

    Science.gov (United States)

    Grizelle Gonzalez; Ruth E. Ley; Steven K. Schmidt; Xiaoming Zou; Timothy R. Seastedt

    2001-01-01

    Soil fauna can influence soil processes through interactions with the microbial community. Due to the complexity of the functional roles of fauna and their effects on microbes, little consensus has been reached on the extent to which soil fauna can regulate microbial activities. We quantified soil microbial biomass and maximum growth rates in control and fauna-excluded...

  13. Promoting Sustainable Forest Management Among Stakeholders in the Prince Albert Model Forest, Canada

    Directory of Open Access Journals (Sweden)

    Glen T Hvenegaard

    2015-01-01

    Full Text Available Model Forests are partnerships for shared decision-making to support social, environmental, and economic sustainability in forest management. Relationships among sustainable forest management partners are often strained, but the Prince Albert Model Forest (PAMF represents a process of effective stakeholder involvement, cooperative relationships, visionary planning, and regional landscape management. This article seeks to critically examine the history, drivers, accomplishments, and challenges associated with the PAMF. Four key phases are discussed, representing different funding levels, planning processes, research projects, and partners. Key drivers in the PAMF were funding, urgent issues, provincial responsibility, core of committed people, evolving governance, desire for a neutral organisation, role of protected areas, and potential for mutual benefits. The stakeholders involved in the Model Forest, including the forest industry and associated groups, protected areas, Aboriginal groups, local communities, governments, and research groups, were committed to the project, cooperated on many joint activities, provided significant staffing and financial resources, and gained many benefits to their own organisations. Challenges included declining funding, changing administrative structures, multiple partners, and rotating representatives. The PAMF process promoted consultative and integrated land resource management in the region, and demonstrated the positive results of cooperation between stakeholders interested in sustainable forest management.

  14. Elevational sensitivity in an Asian 'hotspot': moth diversity across elevational gradients in tropical, sub-tropical and sub-alpine China.

    Science.gov (United States)

    Ashton, L A; Nakamura, A; Burwell, C J; Tang, Y; Cao, M; Whitaker, T; Sun, Z; Huang, H; Kitching, R L

    2016-05-23

    South-western China is widely acknowledged as a biodiversity 'hotspot': there are high levels of diversity and endemism, and many environments are under significant anthropogenic threats not least climate warming. Here, we explore diversity and compare response patterns of moth assemblages among three elevational gradients established within different climatic bioregions - tropical rain forest, sub-tropical evergreen broad-leaved forest and sub-alpine coniferous forest in Yunnan Province, China. We hypothesised that tropical assemblages would be more elevationally stratified than temperate assemblages, and tropical species would be more elevationally restricted than those in the temperate zone. Contrary to our hypothesis, the moth fauna was more sensitive to elevational differences within the temperate transect, followed by sub-tropical and tropical transects. Moths in the cooler and more seasonal temperate sub-alpine gradient showed stronger elevation-decay beta diversity patterns, and more species were restricted to particular elevational ranges. Our study suggests that moth assemblages are under threat from future climate change and sub-alpine rather than tropical faunas may be the most sensitive to climate change. These results improve our understanding of China's biodiversity and can be used to monitor future changes to herbivore assemblages in a 'hotspot' of biodiversity.

  15. Elevational sensitivity in an Asian ‘hotspot’: moth diversity across elevational gradients in tropical, sub-tropical and sub-alpine China

    Science.gov (United States)

    Ashton, L. A.; Nakamura, A.; Burwell, C. J.; Tang, Y.; Cao, M.; Whitaker, T.; Sun, Z.; Huang, H.; Kitching, R. L.

    2016-01-01

    South-western China is widely acknowledged as a biodiversity ‘hotspot’: there are high levels of diversity and endemism, and many environments are under significant anthropogenic threats not least climate warming. Here, we explore diversity and compare response patterns of moth assemblages among three elevational gradients established within different climatic bioregions - tropical rain forest, sub-tropical evergreen broad-leaved forest and sub-alpine coniferous forest in Yunnan Province, China. We hypothesised that tropical assemblages would be more elevationally stratified than temperate assemblages, and tropical species would be more elevationally restricted than those in the temperate zone. Contrary to our hypothesis, the moth fauna was more sensitive to elevational differences within the temperate transect, followed by sub-tropical and tropical transects. Moths in the cooler and more seasonal temperate sub-alpine gradient showed stronger elevation-decay beta diversity patterns, and more species were restricted to particular elevational ranges. Our study suggests that moth assemblages are under threat from future climate change and sub-alpine rather than tropical faunas may be the most sensitive to climate change. These results improve our understanding of China’s biodiversity and can be used to monitor future changes to herbivore assemblages in a ‘hotspot’ of biodiversity. PMID:27211989

  16. MODELING PRECIPITATION DEPENDENT FOREST RESILIENCE IN INDIA

    Directory of Open Access Journals (Sweden)

    P. Das

    2018-04-01

    Full Text Available The impact of long term climate change that imparts stress on forest could be perceived by studying the regime shift of forest ecosystem. With the change of significant precipitation, forest may go through density change around globe at different spatial and temporal scale. The 100 class high resolution (60 meter spatial resolution Indian vegetation type map was used in this study recoded into four broad categories depending on phrenology as (i forest, (ii scrubland, (iii grassland and (iv treeless area. The percentage occupancy of forest, scrub, grass and treeless were observed as 19.9 %, 5.05 %, 1.89 % and 7.79 % respectively. Rest of the 65.37 % land area was occupied by the cropland, built-up, water body and snow covers. The majority forest cover were appended into a 5 km × 5 km grid, along with the mean annual precipitation taken from Bioclim data. The binary presence and absence of different vegetation categories in relates to the annual precipitation was analyzed to calculate their resilience expressed in probability values ranging from 0 to 1. Forest cover observed having resilience probability (Pr < 0.3 in only 0.3 % (200 km2 of total forest cover in India, which was 4.3 % < 0.5 Pr. Majority of the scrubs and grass (64.92 % Pr < 0.5 from North East India which were the shifting cultivation lands showing low resilience, having their high tendency to be transform to forest. These results have spatial explicitness to highlight the resilient and non-resilient distribution of forest, scrub and grass, and treeless areas in India.

  17. FOREST ECOSYSTEM DYNAMICS ASSESSMENT AND PREDICTIVE MODELLING IN EASTERN HIMALAYA

    Directory of Open Access Journals (Sweden)

    S. P. S. Kushwaha

    2012-09-01

    Full Text Available This study focused on the forest ecosystem dynamics assessment and predictive modelling deforestation and forest cover prediction in a part of north-eastern India i.e. forest areas along West Bengal, Bhutan, Arunachal Pradesh and Assam border in Eastern Himalaya using temporal satellite imagery of 1975, 1990 and 2009 and predicted forest cover for the period 2028 using Cellular Automata Markov Modedel (CAMM. The exercise highlighted large-scale deforestation in the study area during 1975–1990 as well as 1990–2009 forest cover vectors. A net loss of 2,334.28 km2 forest cover was noticed between 1975 and 2009, and with current rate of deforestation, a forest area of 4,563.34 km2 will be lost by 2028. The annual rate of deforestation worked out to be 0.35 and 0.78% during 1975–1990 and 1990–2009 respectively. Bamboo forest increased by 24.98% between 1975 and 2009 due to opening up of the forests. Forests in Kokrajhar, Barpeta, Darrang, Sonitpur, and Dhemaji districts in Assam were noticed to be worst-affected while Lower Subansiri, West and East Siang, Dibang Valley, Lohit and Changlang in Arunachal Pradesh were severely affected. Among different forest types, the maximum loss was seen in case of sal forest (37.97% between 1975 and 2009 and is expected to deplete further to 60.39% by 2028. The tropical moist deciduous forest was the next category, which decreased from 5,208.11 km2 to 3,447.28 (33.81% during same period with further chances of depletion to 2,288.81 km2 (56.05% by 2028. It noted progressive loss of forests in the study area between 1975 and 2009 through 1990 and predicted that, unless checked, the area is in for further depletion of the invaluable climax forests in the region, especially sal and moist deciduous forests. The exercise demonstrated high potential of remote sensing and geographic information system for forest ecosystem dynamics assessment and the efficacy of CAMM to predict the forest cover change.

  18. Modeling soil erosion and transport on forest landscape

    Science.gov (United States)

    Ge Sun; Steven G McNulty

    1998-01-01

    Century-long studies on the impacts of forest management in North America suggest sediment can cause major reduction on stream water quality. Soil erosion patterns in forest watersheds are patchy and heterogeneous. Therefore, patterns of soil erosion are difficult to model and predict. The objective of this study is to develop a user friendly management tool for land...

  19. Alternative business models for forest - dependent communities in ...

    African Journals Online (AJOL)

    The dominant mode of business practice in the African forest sector – especially in the high forest cover regions – comes in the form of concessionaires operating on publicly held lands. Increasingly, however, the concession - based model is being challenged. Is it socially and environmentally sustainable? Does it lead to ...

  20. Using landscape disturbance and succession models to support forest management

    Science.gov (United States)

    Eric J. Gustafson; Brian R. Sturtevant; Anatoly S. Shvidenko; Robert M. Scheller

    2010-01-01

    Managers of forested landscapes must account for multiple, interacting ecological processes operating at broad spatial and temporal scales. These interactions can be of such complexity that predictions of future forest ecosystem states are beyond the analytical capability of the human mind. Landscape disturbance and succession models (LDSM) are predictive and...

  1. Modeling population dynamics and woody biomass of Alaska coastal forest

    Science.gov (United States)

    Randy L. Peterson; Jingjing Liang; Tara M. Barrett

    2014-01-01

    Alaska coastal forest, 6.2 million ha in size, has been managed in the past mainly through clearcutting. Declining harvest and dwindling commercial forest resources over the past 2 decades have led to increased interest in management of young-growth stands and utilization of woody biomass for bioenergy. However, existing models to support these new management systems...

  2. Light in Tropical Forest Models: What Detail Matters?

    Science.gov (United States)

    Shenkin, A.; Bentley, L. P.; Asner, G. P.; Malhi, Y.

    2014-12-01

    Representations of light in models of tropical forests are typically unconstrained by field data and rife with assumptions, and for good reason: forest light environments are highly variable, difficult and onerous to predict, and the value of improved prediction is unclear. Still, the question remains: how detailed must our models be to be accurate enough, yet simple enough to be able to scale them from plots to landscapes? Here we use field data to constrain 1-D, 2-D, and 3-D light models and integrate them with simple forest models to predict net primary production (NPP) across an Andes-to-Amazon elevation transect in Peru. Field data consist of novel vertical light profile measurements coupled with airborne LiDAR (light detection and ranging) data from the Carnegie Airborne Observatory. Preliminary results indicate that while 1-D models may be "good-enough" and highly-scalable where forest structure is relatively homogenous, more complex models become important as forest structure becomes more heterogeneous. We discuss the implications our results hold for prediction of NPP under a changing climate, and suggest paths forward for useful proxies of light availability in forests to improve and scale up forest models.

  3. Fuel deposition rates of montane and subalpine conifers in the central Sierra Nevada, California, USA

    Science.gov (United States)

    van Wagtendonk, J.W.; Moore, P.E.

    2010-01-01

    Fire managers and researchers need information on fuel deposition rates to estimate future changes in fuel bed characteristics, determine when forests transition to another fire behavior fuel model, estimate future changes in fuel bed characteristics, and parameterize and validate ecosystem process models. This information is lacking for many ecosystems including the Sierra Nevada in California, USA. We investigated fuel deposition rates and stand characteristics of seven montane and four subalpine conifers in the Sierra Nevada. We collected foliage, miscellaneous bark and crown fragments, cones, and woody fuel classes from four replicate plots each in four stem diameter size classes for each species, for a total of 176 sampling sites. We used these data to develop predictive equations for each fuel class and diameter size class of each species based on stem and crown characteristics. There were consistent species and diameter class differences in the annual amount of foliage and fragments deposited. Foliage deposition rates ranged from just over 50 g m-2 year-1 in small diameter mountain hemlock stands to ???300 g m-2 year-1 for the three largest diameter classes of giant sequoia. The deposition rate for most woody fuel classes increased from the smallest diameter class stands to the largest diameter class stands. Woody fuel deposition rates varied among species as well. The rates for the smallest woody fuels ranged from 0.8 g m-2 year-1 for small diameter stands of Jeffrey pine to 126.9 g m-2 year-1 for very large diameter stands of mountain hemlock. Crown height and live crown ratio were the best predictors of fuel deposition rates for most fuel classes and species. Both characteristics reflect the amount of crown biomass including foliage and woody fuels. Relationships established in this study allow predictions of fuel loads to be made on a stand basis for each of these species under current and possible future conditions. These predictions can be used to

  4. [Maples at the sub-Alpine vegetation belt: a long history].

    Science.gov (United States)

    David, F; Barbero, M

    2001-02-01

    Pollen analysis was carried out on lacustrine sediment of a small hollow (15 m x 25 m) at the treeless sub-Alpine belt (202 m) of the inner Maurienne valley in the northern French Alps. A 2,500-year-long maple settlement was demonstrared. Three AMS dates of terrestrial plant macroremains support the chronology. First, Betula and Salix spread prior to 9,000 C14 BP. The first pollen grains of Acer, Abies and Pinus cembra are quoted at 8,600 C14 BP. High frequencies of Alnus glutinosa/incana (20%) and Acer (10%) show that mixed communities of Acer and Alnus persisted above the mountainous Abies forest between 7,490 and 5,850 C14 BP. After 5,850 C14 BP, the decrease in Acer stands could be attributed to fire as suggested by the strong increase in Betula and by the delayed expansion of Pinus cembra.

  5. Evaluating the Importance of Plant Functional Traits: the Subalpine and Alpine

    Science.gov (United States)

    Sanchez, A.; Smith, W. K.

    2011-12-01

    Over the past several decades, researchers have attempted to characterize plant groups according to traits that are considered functional, i.e. contributing significantly to fitness. Due to the complexity of measuring fitness, the capability for photosynthetic carbon gain is often used as a proxy. Thus, this approach correlates structural differences to photosynthetic performance, especially those differences that are known to be associated with photosynthesis, are easily measured and inexpensive. At the often sharp boundary between the subalpine forest and alpine community (treeline ecotone), plant structural traits change dramatically, i.e. tall evergreen trees give way abruptly to low-stature shrubs, grasses, forbs, and herbs. Yet, the differences in functional traits, so abundant in the literature for a variety of species and communities, have not been compared contiguous communities such as the subalpine forest and alpine. Can differences in functional traits already identified in the literature also be used to characterize species of these two contrasting communities? Or are there other traits that are most functional and/or, possibly, unique to each community and not the most popular traits reported so far in the literature. Also, does the community structure itself help determine functional traits? For example, the top ten most frequently studied traits (145 total papers from approximately 63 different refereed journals) considered functional include the following (% of the 145 publications): specific leaf area or mass (SLA or SLM 39%), plant height (36%), leaf nitrogen content (34%), leaf size (19%), leaf area (16%), leaf photosynthetic performance (15%), leaf dry matter content (LDMC 15%), leaf mass per unit leaf area (LMA 15%), leaf thickness (15%), and seed mass (14%). In addition, another 120 traits were mentioned as functional, although all fell below a 14% citation rate. Particular focus was placed on this group due to the possibility that they might

  6. Modeling forest disturbance and recovery in secondary subtropical dry forests of Puerto Rico

    Science.gov (United States)

    Holm, J. A.; Shugart, H. H., Jr.; Van Bloem, S. J.

    2015-12-01

    Because of human pressures, the need to understand and predict the long-term dynamics of subtropical dry forests is urgent. Through modifications to the ZELIG vegetation demographic model, including the development of species- and site-specific parameters and internal modifications, the capability to predict forest change within the Guanica State Forest in Puerto Rico can now be accomplished. One objective was to test the capability of this new model (i.e. ZELIG-TROP) to predict successional patterns of secondary forests across a gradient of abandoned fields currently being reclaimed as forests. Model simulations found that abandoned fields that are on degraded lands have a delayed response to fully recover and reach a mature forest status during the simulated time period; 200 years. The forest recovery trends matched predictions published in other studies, such that attributes involving early resource acquisition (i.e. canopy height, canopy coverage, density) were the fastest to recover, but attributes used for structural development (i.e. biomass, basal area) were relatively slow in recovery. Biomass and basal area, two attributes that tend to increase during later successional stages, are significantly lower during the first 80-100 years of recovery compared to a mature forest, suggesting that the time scale of resilience in subtropical dry forests needs to be partially redefined. A second objective was to investigate the long and short-term effects of increasing hurricane disturbances on vegetation structure and dynamics, due to hurricanes playing an important role in maintaining dry forest structure in Puerto Rico. Hurricane disturbance simulations within ZELIG-TROP predicted that increasing hurricane intensity (i.e. up to 100% increase) did not lead to a large shift in long-term AGB or NPP. However, increased hurricane frequency did lead to a 5-40% decrease in AGB, and 32-50% increase in NPP, depending on the treatment. In addition, the modeling approach used

  7. Development and Verification of CFD Models for Modeling Wind Conditions on Forested Wind Turbine Sites

    DEFF Research Database (Denmark)

    Andersen, Morten Q.; Mortensen, Kasper; Nielsen, Daniel E.

    2009-01-01

    This paper describes a proposed CFD model to simulate the wind conditions on a forested site. The model introduces porous subdomains representing the forests in the terrain. Obtained simulation values are compared to field measurements in- and outside a forest. Initial results are very promising...

  8. Provenance variability in nursery growth of subalpine fir

    Science.gov (United States)

    Charlie Cartwright; Cheng Ying

    2011-01-01

    Subalpine fir (Abies lasiocarpa [Hook] Nutt.) is a wide-ranging, high-elevation species in the interior of British Columbia. It is commonly harvested for lumber, but replanting of it is limited. Some reticence is based upon wood quality and rate of growth, but there are also seed and nursery culturing difficulties. This study investigated seedling growth traits of 111...

  9. Modelling interactions of carbon dioxide, forests, and climate

    International Nuclear Information System (INIS)

    Luxmoore, R.J.; Baldocchi, D.D.

    1994-01-01

    Atmospheric carbon dioxide is rising and forests and climate is changing exclamation point This combination of fact and premise may be evaluated at a range of temporal and spatial scales with the aid of computer simulators describing the interrelationships between forest vegetation, litter and soil characteristics, and appropriate meteorological variables. Some insights on the effects of climate on the transfers of carbon and the converse effect of carbon transfer on climate are discussed as a basis for assessing the significance of feedbacks between vegetation and climate under conditions of rising atmospheric carbon dioxide. Three main classes of forest models are reviewed. These are physiologically-based models, forest succession simulators based on the JABOWA model, and ecosystem-carbon budget models that use compartment transfer rates with empirically estimated coefficients. Some regression modeling approaches are also outlined. Energy budget models applied to forests and grasslands are also reviewed. This review presents examples of forest models; a comprehensive discussion of all available models is not undertaken

  10. Mapping regional forest fire probability using artificial neural network model in a Mediterranean forest ecosystem

    Directory of Open Access Journals (Sweden)

    Onur Satir

    2016-09-01

    Full Text Available Forest fires are one of the most important factors in environmental risk assessment and it is the main cause of forest destruction in the Mediterranean region. Forestlands have a number of known benefits such as decreasing soil erosion, containing wild life habitats, etc. Additionally, forests are also important player in carbon cycle and decreasing the climate change impacts. This paper discusses forest fire probability mapping of a Mediterranean forestland using a multiple data assessment technique. An artificial neural network (ANN method was used to map forest fire probability in Upper Seyhan Basin (USB in Turkey. Multi-layer perceptron (MLP approach based on back propagation algorithm was applied in respect to physical, anthropogenic, climate and fire occurrence datasets. Result was validated using relative operating characteristic (ROC analysis. Coefficient of accuracy of the MLP was 0.83. Landscape features input to the model were assessed statistically to identify the most descriptive factors on forest fire probability mapping using the Pearson correlation coefficient. Landscape features like elevation (R = −0.43, tree cover (R = 0.93 and temperature (R = 0.42 were strongly correlated with forest fire probability in the USB region.

  11. Using Random Forest Models to Predict Organizational Violence

    Science.gov (United States)

    Levine, Burton; Bobashev, Georgly

    2012-01-01

    We present a methodology to access the proclivity of an organization to commit violence against nongovernment personnel. We fitted a Random Forest model using the Minority at Risk Organizational Behavior (MAROS) dataset. The MAROS data is longitudinal; so, individual observations are not independent. We propose a modification to the standard Random Forest methodology to account for the violation of the independence assumption. We present the results of the model fit, an example of predicting violence for an organization; and finally, we present a summary of the forest in a "meta-tree,"

  12. Understanding forest-derived biomass supply with GIS modelling

    DEFF Research Database (Denmark)

    Hock, B. K.; Blomqvist, L.; Hall, P.

    2012-01-01

    distribution, and the cost of delivery as forests are frequently remote from energy users. A GIS-based model was developed to predict supply curves of forest biomass material for a site or group of sites, both now and in the future. The GIS biomass supply model was used to assist the New Zealand Energy...... Efficiency and Conservation Authority's development of a national target for biomass use for industrial heat production, to determine potential forest residue volumes for industrial heat and their delivery costs for 19 processing plants of the dairy company Fonterra, and towards investigating options...

  13. Using the Global Forest Products Model (GFPM version 2012)

    Science.gov (United States)

    Joseph Buongiorno; Shushuai Zhu

    2012-01-01

    The purpose of this manual is to enable users of the Global Forest Products Model to: • Install and run the GFPM software • Understand the input data • Change the input data to explore different scenarios • Interpret the output The GFPM is an economic model of global production, consumption and trade of forest products (Buongiorno et al. 2003). The GFPM2012 has data...

  14. Approximating prediction uncertainty for random forest regression models

    Science.gov (United States)

    John W. Coulston; Christine E. Blinn; Valerie A. Thomas; Randolph H. Wynne

    2016-01-01

    Machine learning approaches such as random forest have increased for the spatial modeling and mapping of continuous variables. Random forest is a non-parametric ensemble approach, and unlike traditional regression approaches there is no direct quantification of prediction error. Understanding prediction uncertainty is important when using model-based continuous maps as...

  15. Stand model for upland forests of Southern Arkansas

    Energy Technology Data Exchange (ETDEWEB)

    Mielke, D.L.; Shugart, H.H.; West, D.C.

    1978-06-01

    A forest stand growth and composition simulator (FORAR) was developed by modifying a stand growth model by Shugart and West (1977). FORAR is a functional stand model which used ecological parameters to relate individual tree growth to environment rather than using Markov probability matrices or differential equations to determine single tree or species replacement rates. FORAR simulated tree growth and species composition of upland forests of Union County, Ark., by considering 33 tree species on a /sup 1///sub 12/ ha circular plot.

  16. [Measurement model of carbon emission from forest fire: a review].

    Science.gov (United States)

    Hu, Hai-Qing; Wei, Shu-Jing; Jin, Sen; Sun, Long

    2012-05-01

    Forest fire is the main disturbance factor for forest ecosystem, and an important pathway of the decrease of vegetation- and soil carbon storage. Large amount of carbonaceous gases in forest fire can release into atmosphere, giving remarkable impacts on the atmospheric carbon balance and global climate change. To scientifically and effectively measure the carbonaceous gases emission from forest fire is of importance in understanding the significance of forest fire in the carbon balance and climate change. This paper reviewed the research progress in the measurement model of carbon emission from forest fire, which covered three critical issues, i. e., measurement methods of forest fire-induced total carbon emission and carbonaceous gases emission, affecting factors and measurement parameters of measurement model, and cause analysis of the uncertainty in the measurement of the carbon emissions. Three path selections to improve the quantitative measurement of the carbon emissions were proposed, i. e., using high resolution remote sensing data and improving algorithm and estimation accuracy of burned area in combining with effective fuel measurement model to improve the accuracy of the estimated fuel load, using high resolution remote sensing images combined with indoor controlled environment experiments, field measurements, and field ground surveys to determine the combustion efficiency, and combining indoor controlled environment experiments with field air sampling to determine the emission factors and emission ratio.

  17. Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Saleska, Scott [Univ. of Arizona, Tucson, AZ (United States); Davidson, Eric [Univ. of Arizona, Tucson, AZ (United States); Finzi, Adrien [Boston Univ., MA (United States); Wehr, Richdard [Harvard Univ., Cambridge, MA (United States); Moorcroft, Paul [Harvard Univ., Cambridge, MA (United States)

    2016-01-28

    daytime respiration (by ~100%) in the first half of the growing season at our site, and portrays ecosystem photosynthetic light-use efficiency as declining when in fact it is stable until autumnal senescence. B. Vegetation Phenology and belowground allocation: Findings: 1. Autotrophic respiration (Ra) showed a seasonal pattern, peaking in mid-summer when trees were most active. 2. The effective age of the substrate for belowground respiration is less than 2 weeks. 3. Above and belowground phenology are more synchronous in deciduous hardwood stands than evergreen hemlock stands. 4. The decline in root respiration rates in the fall is related to temperature rather than acclimation of root respiration or substrate limitations. Methodological Issues: 5. The isotopic signatures of autotrophic and heterotrophic respiration are too similar for isotopic partitioning of belowground respiration into these two components at our site—in keeping with the recent findings of Bowling et al. (2015) in a subalpine conifer forest. 6. Artifacts of the trenching method, such as changes in soil moisture and increased carbon substrate from the newly severed roots, are significant and need to be quantified when determining daily to annual estimates of autotrophic and heterotrophic respiration. C. Effects of simulated exudates on priming of microbial decomposition: The stoichiometry of root exudates influences both the amount and the mechanism by which priming occurs. At low C:N, SOC loss is caused by an increase in microbial efficiency. At high C:N, SOC loss is caused by an increase in microbial biomass. D. Modeling with the Ecosystem Demography Model (ED2): 1. Incorporation of 13C tracking to create an isotopically-enabled Ecosystem Demography v2 model (ED2) 2. State-of-the-art parameter optimization methodology developed for improving ED2 model predictions and parameters. 3. Significantly improved model predictions of growth- and maintenance-related carbon fluxes and 13C fluxes

  18. Modeling alternative zoning strategies in forest management

    NARCIS (Netherlands)

    Krcmar, E.; Vertinsky, I.; Kooten, van G.C.

    2003-01-01

    To satisfy public demands for environmental values, forest companies are facing the prospect of a reduction in wood supply and increases in costs. Some Canadian provincial governments have proposed intensifying silviculture in special zones dedicated to timber production as the means for pushing out

  19. Villaflores: Municipal forest fire management model

    Science.gov (United States)

    Pedro Martínez Muñoz; Carlos Alberto Velázquez Sanabria

    2013-01-01

    As provided for in the General Law on Sustainable Forestry Development, the Municipality of Villaflores has worked on a continuous basis since 2002 to reduce the damage caused by forest fires as part of its working agenda, in conjunction with Federal and State agencies and NGOs. The work plan has the following phases: a) Inter-agency coordination:...

  20. Effects of model choice and forest structure on inventory-based estimations of Puerto Rican forest biomass

    Science.gov (United States)

    Thomas J. Brandeis; Maria Del Rocio; Suarez Rozo

    2005-01-01

    Total aboveground live tree biomass in Puerto Rican lower montane wet, subtropical wet, subtropical moist and subtropical dry forests was estimated using data from two forest inventories and published regression equations. Multiple potentially-applicable published biomass models existed for some forested life zones, and their estimates tended to diverge with increasing...

  1. Declining forest productivity in aging forest stands: a modeling analysis of alternative hypotheses

    Energy Technology Data Exchange (ETDEWEB)

    Murty, D.; McMurtrie, R. E. [New South Wales Univ., Sydney, NSW (Australia); Ryan, M. G. [Forest Service, Fort Collins, CO (United States). Rocky Mountain Forest and Range Experiment Station

    1996-01-01

    Various hypotheses regarding the decline in forest net primary productivity (NPP) with age in closed-canopy stands were evaluated by graphical analysis using the G`DAY model. Results indicated that the interaction between decline in stomatal conductance, hence photosynthetic efficiency and decline in soil nutrient availability, provided the most plausible answer to reduced productivity, although the relative importance of these two explanations varied according to certain key model assumptions. Increased sapwood respiration, one of the hypotheses tested, was found to have only a minor effect on the decline of forest productivity. 60 refs., 6 figs.

  2. Forest Mortality in High-Elevation Pine Forests of Eastern California, USA; Influence of Climatic Water Deficit

    Science.gov (United States)

    Millar, C. I.; Westfall, R. D.; Flint, A. L.; Flint, L. E.; Bokach, M. J.; Delany, D. L.

    2011-12-01

    Widespread mortality in high-elevation forests has been increasing across western North American mountains in recent years, with climate, insects, and disease the primary causes. Subalpine forests in the eastern Sierra Nevada, by contrast, have experienced far less mortality than other ranges, and mortality events have been patchy and episodic. This situation, and lack of significant effect of non-native white-pine blister rust, enable investigation of fine-scale response of two subalpine Sierran species, whitebark pine (Pinus albicaulis, PiAl) and limber pine (P. flexilis, PiFl), to climate variability, in particular, climatic water deficit (CWD). We report similarities and differences between the two major mortality events in these pines in the last 150 years: 1988-1992 for PiFl and 2006-ongoing for PiAl. The ultimate cause of tree death was mountain pine beetle (Dendroctonus ponderosae), with climatic factors pre-conditioning stress in both species. Our studies include intensive ecology-plot analyses (both species) and region-wide air-survey forest-mortality detection mapping (PiAl only). We used climatic data from historic weather station data; for CWD, we modeled values from PRISM regional climate projections downscaled to 270 m and applied these to a regional water-balance model. The strongest correlations of ring-width (a measure of tree growth) in both species to climatic variables were to CWD: PiFl, -0.29 and -0.54 for live and dead trees, respectively; PiAl ,-0.19 for both live and dead trees. Correlations of ring-widths to 2-year lagged CWD were higher than to current-year means: PiFl, -0.34 and -0.44 for live and dead trees, respectively; PiAl, -0.43 and -0.46, live and dead trees, respectively. Mean annual CWD values of the mortality plots in the intensive study were 181 mm (PiAl) and 289 mm (PiFl); air surveys showed significantly higher CWD values for PiAl mortality stands than live forests (387 mm and 307 mm, respectively). Correlations of growth to

  3. Meso-scale modeling of a forested landscape

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Arnqvist, Johan; Bergström, Hans

    2014-01-01

    Meso-scale models are increasingly used for estimating wind resources for wind turbine siting. In this study, we investigate how the Weather Research and Forecasting (WRF) model performs using standard model settings in two different planetary boundary layer schemes for a forested landscape and how...

  4. Monitoring, modelling and managing Canada's forest carbon cycle

    International Nuclear Information System (INIS)

    Kurz, W.

    2005-01-01

    This paper presents information concerning the management of carbon stocks both globally and in Canada, with reference to the fact that forests may contribute to carbon emissions problems. Global fossil carbon emissions statistics were provided, as well as data of forest area per capita in Canada and various countries. Details of forest management options and carbon accounting with reference to the Kyoto Protocol were reviewed. An explanation of forest management credits in national accounts was provided. An explanation of carbon sinks and carbon sources was also presented, along with details of stand level carbon dynamics. A model for calculating landscape level carbon stocks was presented, with reference to increasing and decreasing disturbances. A hypothetical landscape example was provided. It was concluded that age-class structure affect the amount of carbon stored in landscape; age-class structure also affect carbon dynamics; and responses reflect the change in disturbance regimes. An overview of international reporting requirements was presented. Canadian harvests equal 54,000 tonnes of carbon per year. It was recommended that managed forests could increase carbon in forests while also managing carbon harvests to meet society's needs. A chart presenting forest management details was presented, along with a hypothetical landscape example and a forecast for cumulative changes after 50 years, The benefits and challenges of forest management were reviewed as well as options regarding salvaging and deforestation avoidance. A carbon budget model was presented. It was concluded that forests in Canada could be used in a greenhouse gas management strategy. However, changes in disturbance may mean the difference between net source or net sink. Details of biomass were presented and multi-mode combustion facilities. The feasibility of biomass as a fuel source was discussed, with reference to hydrogen fuel. Gas composition profiles were provided, as well as details of

  5. Structural Equation Modeling: Theory and Applications in Forest Management

    Directory of Open Access Journals (Sweden)

    Tzeng Yih Lam

    2012-01-01

    Full Text Available Forest ecosystem dynamics are driven by a complex array of simultaneous cause-and-effect relationships. Understanding this complex web requires specialized analytical techniques such as Structural Equation Modeling (SEM. The SEM framework and implementation steps are outlined in this study, and we then demonstrate the technique by application to overstory-understory relationships in mature Douglas-fir forests in the northwestern USA. A SEM model was formulated with (1 a path model representing the effects of successively higher layers of vegetation on late-seral herbs through processes such as light attenuation and (2 a measurement model accounting for measurement errors. The fitted SEM model suggested a direct negative effect of light attenuation on late-seral herbs cover but a direct positive effect of northern aspect. Moreover, many processes have indirect effects mediated through midstory vegetation. SEM is recommended as a forest management tool for designing silvicultural treatments and systems for attaining complex arrays of management objectives.

  6. Modeling Forest Succession among Ecological Land Units in Northern Minnesota

    Directory of Open Access Journals (Sweden)

    George Host

    1998-12-01

    Full Text Available Field and modeling studies were used to quantify potential successional pathways among fine-scale ecological classification units within two geomorphic regions of north-central Minnesota. Soil and overstory data were collected on plots stratified across low-relief ground moraines and undulating sand dunes. Each geomorphic feature was sampled across gradients of topography or soil texture. Overstory conditions were sampled using five variable-radius point samples per plot; soil samples were analyzed for carbon and nitrogen content. Climatic, forest composition, and soil data were used to parameterize the sample plots for use with LINKAGES, a forest growth model that simulates changes in composition and soil characteristics over time. Forest composition and soil properties varied within and among geomorphic features. LINKAGES simulations were using "bare ground" and the current overstory as starting conditions. Northern hardwoods or pines dominated the late-successional communities of morainal and dune landforms, respectively. The morainal landforms were dominated by yellow birch and sugar maple; yellow birch reached its maximum abundance in intermediate landscape positions. On the dune sites, pine was most abundant in drier landscape positions, with white spruce increasing in abundance with increasing soil moisture and N content. The differences in measured soil properties and predicted late-successional composition indicate that ecological land units incorporate some of the key variables that govern forest composition and structure. They further show the value of ecological classification and modeling for developing forest management strategies that incorporate the spatial and temporal dynamics of forest ecosystems.

  7. Using urban forest assessment tools to model bird habitat potential

    Science.gov (United States)

    Lerman, Susannah B.; Nislow, Keith H.; Nowak, David J.; DeStefano, Stephen; King, David I.; Jones-Farrand, D. Todd

    2014-01-01

    The alteration of forest cover and the replacement of native vegetation with buildings, roads, exotic vegetation, and other urban features pose one of the greatest threats to global biodiversity. As more land becomes slated for urban development, identifying effective urban forest wildlife management tools becomes paramount to ensure the urban forest provides habitat to sustain bird and other wildlife populations. The primary goal of this study was to integrate wildlife suitability indices to an existing national urban forest assessment tool, i-Tree. We quantified available habitat characteristics of urban forests for ten northeastern U.S. cities, and summarized bird habitat relationships from the literature in terms of variables that were represented in the i-Tree datasets. With these data, we generated habitat suitability equations for nine bird species representing a range of life history traits and conservation status that predicts the habitat suitability based on i-Tree data. We applied these equations to the urban forest datasets to calculate the overall habitat suitability for each city and the habitat suitability for different types of land-use (e.g., residential, commercial, parkland) for each bird species. The proposed habitat models will help guide wildlife managers, urban planners, and landscape designers who require specific information such as desirable habitat conditions within an urban management project to help improve the suitability of urban forests for birds.

  8. Polychlorinated biphenyls (PCBs) in the atmosphere of sub-alpine northern Italy

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Jimenez, J. [European Commission Joint Research Centre, Institute for Environment and Sustainability, Via Enrico Fermi 2749, Ispra 21027, VA (Italy)], E-mail: javier.castro-jimenez@jrc.it; Dueri, S. [European Commission Joint Research Centre, Institute for Environment and Sustainability, Via Enrico Fermi 2749, Ispra 21027, VA (Italy); Eisenreich, S.J. [European Commission Joint Research Centre, Institute for Health and Consumer Protection, Via Enrico Fermi 2749, Ispra 21027, VA (Italy); Mariani, G.; Skejo, H.; Umlauf, G. [European Commission Joint Research Centre, Institute for Environment and Sustainability, Via Enrico Fermi 2749, Ispra 21027, VA (Italy); Zaldivar, J.M. [European Commission Joint Research Centre, Institute for Health and Consumer Protection, Via Enrico Fermi 2749, Ispra 21027, VA (Italy)

    2009-03-15

    The main objective of this work was to assess the atmospheric concentrations and seasonal variations of selected POPs in a sub-alpine location where few data are available. A monitoring and research station was set up at the JRC Ispra EMEP site (Italy). We present and discuss a one-year data set (2005-2006) on PCB air concentrations. {sigma}7PCBs monthly averaged concentration varied from 31 to 76 pg m{sup -3}. Concentrations in the gas phase (21-72 pg m{sup -3}) were higher than those in the particulate phase (3-10 pg m{sup -3}). Advection of air masses and re-volatilization from local sources seem to play a dominant role as drivers of PCB atmospheric concentrations in the area. Indications of seasonal variation affecting PCB congener patterns and the gas/particulate partitioning were found. Modeling calculations suggest a predominant importance of the wet deposition in this region (1 {mu}g m{sup -2} yr{sup -1} {sigma}7PCBs yearly total wet deposition flux; 650-2400 pg L{sup -1} rainwater concentrations). - Advection of air masses and re-volatilization from local sources play a dominant role as drivers of the PCB atmospheric concentration in sub-alpine northern Italy.

  9. Modeling Mediterranean forest structure using airborne laser scanning data

    Science.gov (United States)

    Bottalico, Francesca; Chirici, Gherardo; Giannini, Raffaello; Mele, Salvatore; Mura, Matteo; Puxeddu, Michele; McRoberts, Ronald E.; Valbuena, Ruben; Travaglini, Davide

    2017-05-01

    The conservation of biological diversity is recognized as a fundamental component of sustainable development, and forests contribute greatly to its preservation. Structural complexity increases the potential biological diversity of a forest by creating multiple niches that can host a wide variety of species. To facilitate greater understanding of the contributions of forest structure to forest biological diversity, we modeled relationships between 14 forest structure variables and airborne laser scanning (ALS) data for two Italian study areas representing two common Mediterranean forests, conifer plantations and coppice oaks subjected to irregular intervals of unplanned and non-standard silvicultural interventions. The objectives were twofold: (i) to compare model prediction accuracies when using two types of ALS metrics, echo-based metrics and canopy height model (CHM)-based metrics, and (ii) to construct inferences in the form of confidence intervals for large area structural complexity parameters. Our results showed that the effects of the two study areas on accuracies were greater than the effects of the two types of ALS metrics. In particular, accuracies were less for the more complex study area in terms of species composition and forest structure. However, accuracies achieved using the echo-based metrics were only slightly greater than when using the CHM-based metrics, thus demonstrating that both options yield reliable and comparable results. Accuracies were greatest for dominant height (Hd) (R2 = 0.91; RMSE% = 8.2%) and mean height weighted by basal area (R2 = 0.83; RMSE% = 10.5%) when using the echo-based metrics, 99th percentile of the echo height distribution and interquantile distance. For the forested area, the generalized regression (GREG) estimate of mean Hd was similar to the simple random sampling (SRS) estimate, 15.5 m for GREG and 16.2 m SRS. Further, the GREG estimator with standard error of 0.10 m was considerable more precise than the SRS

  10. Model of plutonium dynamics in a deciduous forest ecosystem

    International Nuclear Information System (INIS)

    Garten, C.T. Jr.; Gardner, R.H.; Dahlman, R.C.

    1980-01-01

    A linear compartment model with donor-controlled flows between compartments was designed to describe and simulate the behavior of plutonium ( 239 240 Pu) in a contaminated forest ecosystem at Oak Ridge, TN. At steady states predicted by the model, less than 0.25% of the plutonium in the ecosystem resides in biota. Soil is the major repository of plutonium in the forest, and exchanges of plutonium between soil and litter or soil and tree roots were dominant transfers affecting the ecosystem distribution of plutonium. Variation in predicted steady-state amounts of plutonium in the forest, given variability in the model parameters, indicates that our ability to develop models of plutonium transport in ecosystems should improve with greater precision in data from natural environments and a better understanding of sources of variation in plutonium data

  11. Modelling of radionuclide migration in forest ecosystems. A literature review

    Energy Technology Data Exchange (ETDEWEB)

    Avila, R.; Moberg, L.; Hubbard, L.

    1998-03-01

    The Chernobyl accident has clearly shown the long-term effects of a radioactive contamination of forest ecosystems. This report is based on a literature review of models which describe the migration of radionuclides, radioactive caesium in particular, in forest ecosystems. The report describes the particularities of the forest ecosystem, the time dynamics of the contamination, the transfer processes and factors influencing caesium migration. This provides a basis for a discussion of different approaches for modelling caesium migration in the forest. It is concluded that the studied dynamic models include the most relevant transfer processes both for the acute and the long-term phase after a radioactive deposition. However, most models are site specific and do not consider some of the factors responsible for the differences in radionuclide behaviour and distribution in different types of forests. Although model improvements are constrained by the availability of experimental data and by the lack of knowledge of the migration mechanisms some possible improvements are discussed. This report is part of the LANDSCAPE project. -An integrated approach to radionuclide flow in the semi-natural ecosystems underlying exposure pathways to man. 42 refs, 3 tabs, 9 figs.

  12. Modelling of radionuclide migration in forest ecosystems. A literature review

    International Nuclear Information System (INIS)

    Avila, R.; Moberg, L.; Hubbard, L.

    1998-03-01

    The Chernobyl accident has clearly shown the long-term effects of a radioactive contamination of forest ecosystems. This report is based on a literature review of models which describe the migration of radionuclides, radioactive caesium in particular, in forest ecosystems. The report describes the particularities of the forest ecosystem, the time dynamics of the contamination, the transfer processes and factors influencing caesium migration. This provides a basis for a discussion of different approaches for modelling caesium migration in the forest. It is concluded that the studied dynamic models include the most relevant transfer processes both for the acute and the long-term phase after a radioactive deposition. However, most models are site specific and do not consider some of the factors responsible for the differences in radionuclide behaviour and distribution in different types of forests. Although model improvements are constrained by the availability of experimental data and by the lack of knowledge of the migration mechanisms some possible improvements are discussed. This report is part of the LANDSCAPE project. -An integrated approach to radionuclide flow in the semi-natural ecosystems underlying exposure pathways to man

  13. Scaling Forest Management Practices in Earth System Models: Case Study of Southeast and Pacific Northwest Forests

    Science.gov (United States)

    Pourmokhtarian, A.; Becknell, J. M.; Hall, J.; Desai, A. R.; Boring, L. R.; Duffy, P.; Staudhammer, C. L.; Starr, G.; Dietze, M.

    2014-12-01

    A wide array of human-induced disturbances can alter the structure and function of forests, including climate change, disturbance and management. While there have been numerous studies on climate change impacts on forests, interactions of management with changing climate and natural disturbance are poorly studied. Forecasts of the range of plausible responses of forests to climate change and management are need for informed decision making on new management approaches under changing climate, as well as adaptation strategies for coming decades. Terrestrial biosphere models (TBMs) provide an excellent opportunity to investigate and assess simultaneous responses of terrestrial ecosystems to climatic perturbations and management across multiple spatio-temporal scales, but currently do not represent a wide array of management activities known to impact carbon, water, surface energy fluxes, and biodiversity. The Ecosystem Demography model 2 (ED2) incorporates non-linear impacts of fine-scale (~10-1 km) heterogeneity in ecosystem structure both horizontally and vertically at a plant level. Therefore it is an ideal candidate to incorporate different forest management practices and test various hypotheses under changing climate and across various spatial scales. The management practices that we implemented were: clear-cut, conversion, planting, partial harvest, low intensity fire, restoration, salvage, and herbicide. The results were validated against observed data across 8 different sites in the U.S. Southeast (Duke Forest, Joseph Jones Ecological Research Center, North Carolina Loblolly Pine, and Ordway-Swisher Biological Station) and Pacific Northwest (Metolius Research Natural Area, H.J. Andrews Experimental Forest, Wind River Field Station, and Mount Rainier National Park). These sites differ in regards to climate, vegetation, soil, and historical land disturbance as well as management approaches. Results showed that different management practices could successfully

  14. Forest growth and timber quality: crown models and simulation methods for sustainable forest management

    Science.gov (United States)

    Dennis P. Dykstra; Robert A. Monserud

    2009-01-01

    The purpose of the international conference from which these proceedings are drawn was to explore relationships between forest management activities and timber quality. Sessions were organized to explore models and simulation methodologies that contribute to an understanding of tree development over time and the ways that management and harvesting activities can...

  15. Linking an ecosystem model and a landscape model to study forest species response to climate warming

    Science.gov (United States)

    Hong S. He; David J. Mladenoff; Thomas R. Crow

    1999-01-01

    No single model can address forest change from single tree to regional scales. We discuss a framework linking an ecosystem process model {LINKAGES) with a spatial landscape model (LANDIS) to examine forest species responses to climate warming for a large, heterogeneous landscape in northern Wisconsin, USA. Individual species response at the ecosystem scale was...

  16. Radiation dose from Chernobyl forests: assessment using the 'forestpath' model

    International Nuclear Information System (INIS)

    Schell, W.R.; Linkov, I.; Belinkaia, E.; Rimkevich, V.; Zmushko, Yu.; Lutsko, A.; Fifield, F.W.; Flowers, A.G.; Wells, G.

    1996-01-01

    Contaminated forests can contribute significantly to human radiation dose for a few decades after initial contamination. Exposure occurs through harvesting the trees, manufacture and use of forest products for construction materials and paper production, and the consumption of food harvested from forests. Certain groups of the population, such as wild animal hunters and harvesters of berries, herbs and mushrooms, can have particularly large intakes of radionuclides from natural food products. Forestry workers have been found to receive radiation doses several times higher than other groups in the same area. The generic radionuclide cycling model 'forestpath' is being applied to evaluate the human radiation dose and risks to population groups resulting from living and working near the contaminated forests. The model enables calculations to be made to predict the internal and external radiation doses at specific times following the accident. The model can be easily adjusted for dose calculations from other contamination scenarios (such as radionuclide deposition at a low and constant rate as well as complex deposition patterns). Experimental data collected in the forests of Southern Belarus are presented. These data, together with the results of epidemiological studies, are used for model calibration and validation

  17. Modeling Alaska boreal forests with a controlled trend surface approach

    Science.gov (United States)

    Mo Zhou; Jingjing Liang

    2012-01-01

    An approach of Controlled Trend Surface was proposed to simultaneously take into consideration large-scale spatial trends and nonspatial effects. A geospatial model of the Alaska boreal forest was developed from 446 permanent sample plots, which addressed large-scale spatial trends in recruitment, diameter growth, and mortality. The model was tested on two sets of...

  18. Modeling the hydrologic impacts of forest harvesting on Florida flatwoods

    Science.gov (United States)

    Ge Sun; Hans Rierkerk; Nicholas B. Comerford

    1998-01-01

    The great temporal and spatial variability of pine flatwoods hydrology suggests traditional short-term field methods may not be effective in evaluating the hydrologic effects of forest management. The flatwoods model was developed, calibrated and validated specifically for the cypress wetland-pine upland landscape. The model was applied to two typical flatwoods sites...

  19. A Soil Temperature Model for Closed Canopied Forest Stands

    Science.gov (United States)

    James M. Vose; Wayne T. Swank

    1991-01-01

    A microcomputer-based soil temperature model was developed to predict temperature at the litter-soil interface and soil temperatures at three depths (0.10 m, 0.20 m, and 1.25 m) under closed forest canopies. Comparisons of predicted and measured soil temperatures indicated good model performance under most conditions. When generalized parameters describing soil...

  20. Modeling and Validation across Scales: Parametrizing the effect of the forested landscape

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Badger, Merete; Angelou, Nikolas

    be transferred into a parametrization of forests in wind models. The presentation covers three scales: the single tree, the forest edges and clearings, and the large-scale forested landscape in which the forest effects are parameterized with a roughness length. Flow modeling results and validation against...

  1. Forest cover dynamics analysis and prediction modelling using logistic regression model (case study: forest cover at Indragiri Hulu Regency, Riau Province)

    Science.gov (United States)

    Nahib, Irmadi; Suryanta, Jaka

    2017-01-01

    Forest destruction, climate change and global warming could reduce an indirect forest benefit because forest is the largest carbon sink and it plays a very important role in global carbon cycle. To support Reducing Emissions from Deforestation and Forest Degradation (REDD +) program, people pay attention of forest cover changes as the basis for calculating carbon stock changes. This study try to explore the forest cover dynamics as well as the prediction model of forest cover in Indragiri Hulu Regency, Riau Province Indonesia. The study aims to analyse some various explanatory variables associated with forest conversion processes and predict forest cover change using logistic regression model (LRM). The main data used in this study is Land use/cover map (1990 - 2011). Performance of developed model was assessed through a comparison of the predicted model of forest cover change and the actual forest cover in 2011. The analysis result showed that forest cover has decreased continuously between 1990 and 2011, up to the loss of 165,284.82 ha (35.19 %) of forest area. The LRM successfully predicted the forest cover for the period 2010 with reasonably high accuracy (ROC = 92.97 % and 70.26 %).

  2. Nitrogen cycling models and their application to forest harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.W.; Dale, V.H.

    1986-01-01

    The characterization of forest nitrogen- (N-) cycling processes by several N-cycling models (FORCYTE, NITCOMP, FORTNITE, and LINKAGES) is briefly reviewed and evaluated against current knowledge of N cycling in forests. Some important processes (e.g., translocation within trees, N dynamics in decaying leaf litter) appear to be well characterized, whereas others (e.g., N mineralization from soil organic matter, N fixation, N dynamics in decaying wood, nitrification, and nitrate leaching) are poorly characterized, primarily because of a lack of knowledge rather than an oversight by model developers. It is remarkable how well the forest models do work in the absence of data on some key processes. For those systems in which the poorly understood processes could cause major changes in N availability or productivity, the accuracy of model predictions should be examined. However, the development of N-cycling models represents a major step beyond the much simpler, classic conceptual models of forest nutrient cycling developed by early investigators. The new generation of computer models will surely improve as research reveals how key nutrient-cycling processes operate.

  3. A model of forest floor carbon mass for United States forest types

    Science.gov (United States)

    James E. Smith; Linda S. Heath

    2002-01-01

    Includes a large set of published values of forest floor mass and develop large-scale estimates of carbon mass according to region and forest type. Estimates of average forest floor carbon mass per hectare of forest applied to a 1997 summary forest inventory, sum to 4.5 Gt carbon stored in forests of the 48 contiguous United States.

  4. Extreme value modelling of storm damage in Swedish forests

    Directory of Open Access Journals (Sweden)

    A. Bengtsson

    2007-09-01

    Full Text Available Forests cover about 56% of the land area in Sweden and forest damage due to strong winds has been a recurring problem. In this paper we analyse recorded storm damage in Swedish forests for the years 1965–2007. During the period 48 individual storm events with a total damage of 164 Mm³ have been reported with the severe storm on 8 to 9 January 2005, as the worst with 70 Mm³ damaged forest. For the analysis, storm damage data has been normalised to account for the increase in total forest volume over the period.

    We show that, within the framework of statistical extreme value theory, a Poisson point process model can be used to describe these storm damage events. Damage data supports a heavy-tailed distribution with great variability in damage for the worst storm events. According to the model, and in view of available data, the return period for a storm with damage in size of the severe storm of January 2005 is approximately 80 years, i.e. a storm with damage of this magnitude will happen, on average, once every eighty years.

    To investigate a possible temporal trend, models with time-dependent parameters have been analysed but give no conclusive evidence of an increasing trend in the normalised storm damage data for the period. Using a non-parametric approach with a kernel based local-likelihood method gives the same result.

  5. Modeling transient response of forests to climate change.

    Science.gov (United States)

    Dale, Virginia H; Tharp, M Lynn; Lannom, Karen O; Hodges, Donald G

    2010-03-15

    Our hypothesis is that a high diversity of dominant life forms in Tennessee forests conveys resilience to disturbance such as climate change. Because of uncertainty in climate change and their effects, three climate change scenarios for 2030 and 2080 from three General Circulation Models (GCMs) were used to simulate a range of potential climate conditions for the state. These climate changes derive from the Intergovernmental Panel on Climate Change (IPCC) "A1B" storyline that assumes rapid global economic growth. The precipitation and temperature projections from the three GCMs for 2030 and 2080 were related to changes in five ecological provinces using the monthly record of temperature and precipitation from 1980 to 1997 for each 1km cell across the state as aggregated into the provinces. Temperatures are projected to increase in all ecological provinces in all months for all three GCMs for both 2030 and 2080. Precipitation differences from the long-term average are more complex but less striking. The forest ecosystem model LINKAGES was used to simulate conditions for five ecological provinces from 1989 to 2300. Average output projects changes in tree diversity and species composition in all ecological provinces in Tennessee with the greatest changes in the Southern Mixed Forest province. Projected declines in total tree biomass are followed by biomass recovery as species replacement occurs in stands. The Southern Mixed Forest province results in less diversity in dominant trees as well as lower overall biomass than projections for the other four provinces. The biomass and composition changes projected in this study differ from forest dynamics expected without climate change. These results suggest that biomass recovery following climate change is linked to dominant tree diversity in the southeastern forest of the US. The generality of this observation warrants further investigation, for it relates to ways that forest management may influence climate change effects.

  6. Provenance variation in subalpine fir grown as an exotic tree species in Denmark and Iceland

    DEFF Research Database (Denmark)

    Skúlason, Brynjar

    In Denmark and Iceland, there has been increasing interest in the use of subalpine fir (Abies lasiocarpa (Hook.) Nutt.) as an exotic species; in Denmark as a niche product for the Christmas tree market and in Iceland as the main Christmas tree species. A field test with 26 provenances of subalpine...

  7. DRAINMOD-FOREST: Integrated Modeling of Hydrology, Soil Carbon and Nitrogen Dynamics, and Plant Growth for Drained Forests.

    Science.gov (United States)

    Tian, Shiying; Youssef, Mohamed A; Skaggs, R Wayne; Amatya, Devendra M; Chescheir, G M

    2012-01-01

    We present a hybrid and stand-level forest ecosystem model, DRAINMOD-FOREST, for simulating the hydrology, carbon (C) and nitrogen (N) dynamics, and tree growth for drained forest lands under common silvicultural practices. The model was developed by linking DRAINMOD, the hydrological model, and DRAINMOD-N II, the soil C and N dynamics model, to a forest growth model, which was adapted mainly from the 3-PG model. The forest growth model estimates net primary production, C allocation, and litterfall using physiology-based methods regulated by air temperature, water deficit, stand age, and soil N conditions. The performance of the newly developed DRAINMOD-FOREST model was evaluated using a long-term (21-yr) data set collected from an artificially drained loblolly pine ( L.) plantation in eastern North Carolina, USA. Results indicated that the DRAINMOD-FOREST accurately predicted annual, monthly, and daily drainage, as indicated by Nash-Sutcliffe coefficients of 0.93, 0.87, and 0.75, respectively. The model also predicted annual net primary productivity and dynamics of leaf area index reasonably well. Predicted temporal changes in the organic matter pool on the forest floor and in forest soil were reasonable compared to published literature. Both predicted annual and monthly nitrate export were in good agreement with field measurements, as indicated by Nash-Sutcliffe coefficients above 0.89 and 0.79 for annual and monthly predictions, respectively. This application of DRAINMOD-FOREST demonstrated its capability for predicting hydrology and C and N dynamics in drained forests under limited silvicultural practices. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  8. Calibrating and Updating the Global Forest Products Model (GFPM version 2014 with BPMPD)

    Science.gov (United States)

    Joseph Buongiorno; Shushuai Zhu

    2014-01-01

    The Global Forest Products Model (GFPM) is an economic model of global production, consumption, and trade of forest products. An earlier version of the model is described in Buongiorno et al. (2003). The GFPM 2014 has data and parameters to simulate changes of the forest sector from 2010 to 2030. Buongiorno and Zhu (2014) describe how to use the model for simulation....

  9. Calibrating and updating the Global Forest Products Model (GFPM version 2016 with BPMPD)

    Science.gov (United States)

    Joseph Buongiorno; Shushuai  Zhu

    2016-01-01

    The Global Forest Products Model (GFPM) is an economic model of global production, consumption, and trade of forest products. An earlier version of the model is described in Buongiorno et al. (2003). The GFPM 2016 has data and parameters to simulate changes of the forest sector from 2013 to 2030. Buongiorno and Zhu (2015) describe how to use the model for...

  10. Sampling and modeling riparian forest structure and riparian microclimate

    Science.gov (United States)

    Bianca N.I. Eskelson; Paul D. Anderson; Hailemariam. Temesgen

    2013-01-01

    Riparian areas are extremely variable and dynamic, and represent some of the most complex terrestrial ecosystems in the world. The high variability within and among riparian areas poses challenges in developing efficient sampling and modeling approaches that accurately quantify riparian forest structure and riparian microclimate. Data from eight stream reaches that are...

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    We have modelled the total atmospheric OH-reactivity in a boreal forest and investigated the individual contributions from gas phase inorganic species, isoprene, monoterpenes, and methane along with other important VOCs. Daily and seasonal variation in OH-reactivity for the year 2008 was examined...

  12. An enhanced forest classification scheme for modeling vegetation-climate interactions based on national forest inventory data

    Science.gov (United States)

    Majasalmi, Titta; Eisner, Stephanie; Astrup, Rasmus; Fridman, Jonas; Bright, Ryan M.

    2018-01-01

    Forest management affects the distribution of tree species and the age class of a forest, shaping its overall structure and functioning and in turn the surface-atmosphere exchanges of mass, energy, and momentum. In order to attribute climate effects to anthropogenic activities like forest management, good accounts of forest structure are necessary. Here, using Fennoscandia as a case study, we make use of Fennoscandic National Forest Inventory (NFI) data to systematically classify forest cover into groups of similar aboveground forest structure. An enhanced forest classification scheme and related lookup table (LUT) of key forest structural attributes (i.e., maximum growing season leaf area index (LAImax), basal-area-weighted mean tree height, tree crown length, and total stem volume) was developed, and the classification was applied for multisource NFI (MS-NFI) maps from Norway, Sweden, and Finland. To provide a complete surface representation, our product was integrated with the European Space Agency Climate Change Initiative Land Cover (ESA CCI LC) map of present day land cover (v.2.0.7). Comparison of the ESA LC and our enhanced LC products (https://doi.org/10.21350/7zZEy5w3) showed that forest extent notably (κ = 0.55, accuracy 0.64) differed between the two products. To demonstrate the potential of our enhanced LC product to improve the description of the maximum growing season LAI (LAImax) of managed forests in Fennoscandia, we compared our LAImax map with reference LAImax maps created using the ESA LC product (and related cross-walking table) and PFT-dependent LAImax values used in three leading land models. Comparison of the LAImax maps showed that our product provides a spatially more realistic description of LAImax in managed Fennoscandian forests compared to reference maps. This study presents an approach to account for the transient nature of forest structural attributes due to human intervention in different land models.

  13. Historical forest biomass dynamics modelled with Landsat spectral trajectories

    Science.gov (United States)

    Gómez, Cristina; White, Joanne C.; Wulder, Michael A.; Alejandro, Pablo

    2014-07-01

    Estimation of forest aboveground biomass (AGB) is informative of the role of forest ecosystems in local and global carbon budgets. There is a need to retrospectively estimate biomass in order to establish a historical baseline and enable reporting of change. In this research, we used temporal spectral trajectories to inform on forest successional development status in support of modelling and mapping of historic AGB for Mediterranean pines in central Spain. AGB generated with ground plot data from the Spanish National Forest Inventory (NFI), representing two collection periods (1990 and 2000), are linked with static and dynamic spectral data as captured by Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) sensors over a 25 year period (1984-2009). The importance of forest structural complexity on the relationship between AGB and spectral vegetation indices is revealed by the analysis of wavelet transforms. Two-dimensional (2D) wavelet transforms support the identification of spectral trajectory patterns of forest stands that in turn, are associated with traits of individual NFI plots, using a flexible algorithm sensitive to capturing time series similarity. Single-date spectral indices, temporal trajectories, and temporal derivatives associated with succession are used as input variables to non-parametric decision trees for modelling, estimation, and mapping of AGB and carbon sinks over the entire study area. Results indicate that patterns of change found in Normalized Difference Vegetation Index (NDVI) values are associated and relate well to classes of forest AGB. The Tasseled Cap Angle (TCA) index was found to be strongly related with forest density, although the related patterns of change had little relation with variability in historic AGB. By scaling biomass models through small (˜2.5 ha) spatial objects defined by spectral homogeneity, the AGB dynamics in the period 1990-2000 are mapped (70% accuracy when validated with plot values of

  14. The vertical signature of gophers on the critical zone in the Colorado Front Range subalpine zone

    Science.gov (United States)

    Winchell, E. W.; Anderson, R. S.; Kaste, J. M.

    2016-12-01

    In the subalpine zone of the Colorado Front Range (CFR), the northern pocket gopher performs much of the geomorphic work. Whereas the impact of gophers is clear on the land surface, it is less obvious in the vertical. Digging data illustrate the importance of gophers within the meadows in this till-covered landscape and imply century-scale turnover time of the upper soil. To quantify the signature of gopher activity in the vertical, we collected 1) field data that illustrates the increased probability of encountering coarser clasts at 9-18 cm depths and 2) 137Cs and 210Pbex activity profiles that monotonically decline within the top 18 cm. Traditional advection-diffusion soil mixing models utilized in both marine and terrestrial environments fail to fit simultaneously the fallout nuclide profiles, and cannot explain the increase in grain size at depth. This motivates construction of a numerical model in which gopher digging activity is explicitly represented. Our algorithm emulates the tunneling-mounding activities of gophers in which smaller clasts are lofted to the surface from an excavated tunnel; the subsequent collapse of the tunnel shuffles downward all clasts above the tunnel. We track the profiles of grain sizes and of 137Cs and 210Pbex concentrations. Higher than average concentrations of coarse grains, stonelines, arise over century timescales from the preferential lofting of fine grains and the avoidance of coarse grains during digging. 137Cs and 210Pbex profiles can be simultaneously fit only if the gopher activity at this particular sampling site ceased roughly several decades prior to our sampling. Field data and modeling together therefore provide insight into the history of the landscape on both century and decadal timescales in the face of gopher activity. We suggest that these `rototilled' meadows repeatedly self-organize in the aftermath of fires to allow the signature of gopher activity to be written throughout the subalpine zone of the CFR.

  15. Modelling nutrient cycling in forest ecosystems; Modellering av naeringssyklus i skogoekosystemer

    Energy Technology Data Exchange (ETDEWEB)

    Kvindesland, Sheila H.S.B.

    1997-12-31

    Acid deposition`s threat to fresh water and forest environments became an issue in the late 1960s. Acid deposition and forest nutrient cycling then began to be researched in greater co-operation. This thesis studies nutrient cycling processes in Norway spruce forests, emphasizing the effects on soil chemical properties, soil solution chemistry and streamwater chemistry. It investigates the effects of different aged stands on nutrient cycling and sets up nutrient budgets of the base cations and nitrogen at two sites in Norway. It also selects, documents, calibrates, tests and improves nutrient cycling models for use in Norwegian forests. 84 refs., 44 figs., 46 tabs.

  16. Model for estimating air pollutant uptake by forests: calculation of forest absorption of sulfur dioxide from dispersed sources

    International Nuclear Information System (INIS)

    Murphy, C.E. Jr.; Sinclair, T.R.; Knoerr, K.R.

    1975-01-01

    The computer model presented in this paper is designed to estimate the uptake of air pollutants by forests. The model utilizes submodels to describe atmospheric diffusion immediately above and within the canopy, and into the sink areas within or on the trees. The program implementing the model is general and can be used with only minor changes for any gaseous pollutant. To illustrate the utility of the model, estimates are made of the sink strength of forests for sulfur dioxide. The results agree with experimentally derived estimates of sulfur dioxide uptake in crops and forest trees. (auth)

  17. MODELING THE Ly α FOREST IN COLLISIONLESS SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Sorini, Daniele; Oñorbe, José; Hennawi, Joseph F. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Lukić, Zarija, E-mail: sorini@mpia-hd.mpg.de [Lawrence Berkeley National Laboratory, CA 94720-8139 (United States)

    2016-08-20

    Cosmological hydrodynamic simulations can accurately predict the properties of the intergalactic medium (IGM), but only under the condition of retaining the high spatial resolution necessary to resolve density fluctuations in the IGM. This resolution constraint prohibits simulating large volumes, such as those probed by BOSS and future surveys, like DESI and 4MOST. To overcome this limitation, we present “Iteratively Matched Statistics” (IMS), a novel method to accurately model the Ly α forest with collisionless N -body simulations, where the relevant density fluctuations are unresolved. We use a small-box, high-resolution hydrodynamic simulation to obtain the probability distribution function (PDF) and the power spectrum of the real-space Ly α forest flux. These two statistics are iteratively mapped onto a pseudo-flux field of an N -body simulation, which we construct from the matter density. We demonstrate that our method can reproduce the PDF, line of sight and 3D power spectra of the Ly α forest with good accuracy (7%, 4%, and 7% respectively). We quantify the performance of the commonly used Gaussian smoothing technique and show that it has significantly lower accuracy (20%–80%), especially for N -body simulations with achievable mean inter-particle separations in large-volume simulations. In addition, we show that IMS produces reasonable and smooth spectra, making it a powerful tool for modeling the IGM in large cosmological volumes and for producing realistic “mock” skies for Ly α forest surveys.

  18. Consequences of increasing bioenergy demand on wood and forests: an application of the global forest products model

    Science.gov (United States)

    Joseph Buongiorno; Ronald Raunikar; Shushuai Zhu

    2011-01-01

    The Global Forest Products Model (GFPM) was applied to project the consequences for the global forest sector of doubling the rate of growth of bioenergy demand relative to a base scenario, other drivers being maintained constant. The results showed that this would lead to the convergence of the price of fuelwood and industrial roundwood, raising the price of industrial...

  19. Model-specification uncertainty in future forest pest outbreak.

    Science.gov (United States)

    Boulanger, Yan; Gray, David R; Cooke, Barry J; De Grandpré, Louis

    2016-04-01

    Climate change will modify forest pest outbreak characteristics, although there are disagreements regarding the specifics of these changes. A large part of this variability may be attributed to model specifications. As a case study, we developed a consensus model predicting spruce budworm (SBW, Choristoneura fumiferana [Clem.]) outbreak duration using two different predictor data sets and six different correlative methods. The model was used to project outbreak duration and the uncertainty associated with using different data sets and correlative methods (=model-specification uncertainty) for 2011-2040, 2041-2070 and 2071-2100, according to three forcing scenarios (RCP 2.6, RCP 4.5 and RCP 8.5). The consensus model showed very high explanatory power and low bias. The model projected a more important northward shift and decrease in outbreak duration under the RCP 8.5 scenario. However, variation in single-model projections increases with time, making future projections highly uncertain. Notably, the magnitude of the shifts in northward expansion, overall outbreak duration and the patterns of outbreaks duration at the southern edge were highly variable according to the predictor data set and correlative method used. We also demonstrated that variation in forcing scenarios contributed only slightly to the uncertainty of model projections compared with the two sources of model-specification uncertainty. Our approach helped to quantify model-specification uncertainty in future forest pest outbreak characteristics. It may contribute to sounder decision-making by acknowledging the limits of the projections and help to identify areas where model-specification uncertainty is high. As such, we further stress that this uncertainty should be strongly considered when making forest management plans, notably by adopting adaptive management strategies so as to reduce future risks. © 2015 Her Majesty the Queen in Right of Canada Global Change Biology © 2015 Published by John

  20. Imagining Future Forests: What Models Can Learn from Field Data.

    Science.gov (United States)

    Ward, E. J.; Domec, J. C.; Laviner, M. A.; Fox, T. D.; Sun, G.; McNulty, S. G.; King, J.; Noormets, A.

    2014-12-01

    General circulation models predict that future forests in the U.S. Southeast will experience higher temperatures and more variable precipitation in the future, resulting in a moderate decrease in water availability (precipitation minus evapotranspiration), though considerable uncertainty in and disagreement between projections remain. The Pine Integrated Network: Education, Mitigation, and Adaptation Project (PINEMAP) represents an effort to understand the future of 20 million acres of planted pine forests managed by private landowners in the Atlantic and Gulf coastal states. Decades of productivity research on loblolly pine (Pinus taeda) has led to a widespread practice of mid-rotation fertilization of loblolly plantations, supplying additional nutrients as stands approach canopy closure. It remains an open question what the effects of fertilization of pine forests in this region will be in the face of periodic or persistent droughts, in terms of forest water use and its implications to other water uses downstream. Therefore, we will review key results from past ecophysiological research on the responses of loblolly pine to fertilization, elevated CO2 and water availability, as well as a recent PINEMAP field trial of fertilization and drought imposed through rainfall displacement over two growing seasons. Despite high rainfall in 2013 (1224 mm compared an average 1120 mm) and a lack of leaf area response, transpiration decreased in response to fertilization and through rainfall displacement. Treatment differences were greatest in the growing season of 2013, when transpiration was on average 13.6, 20.2 and 28.7% lower in the rainfall displacement, fertilization and combined treatment than the control (46 mm/month), respectively. We will conclude by reviewing the important lessons from this research for regional models of future forests in this region in terms of LAI, transpiration, growth and water use efficiency.

  1. Modeling directional thermal radiance from a forest canopy

    International Nuclear Information System (INIS)

    McGuire, M.J.; Balick, L.K.; Smith, J.A.; Hutchison, B.A.

    1989-01-01

    Recent advances in remote sensing technology have increased interest in utilizing the thermal-infared region to gain additional information about surface features such as vegetation canopies. Studies have shown that sensor view angle, canopy structure, and percentage of canopy coverage can affect the response of a thermal sensor. These studies have been primarily of agricultural regions and there have been relatively few examples describing the thermal characteristics of forested regions. This paper describes an extension of an existing thermal vegetation canopy radiance model which has been modified to partially account for the geometrically rough structure of a forest canopy. Fourier series expansion of a canopy height profile is used to calculate improved view factors which partially account for the directional variations in canopy thermal radiance transfers. The original and updated radiance model predictions are compared with experimental data obtained over a deciduous (oak-hickory) forest site. The experimental observations are also used to document azimuthal and nadir directional radiance variations. Maximum angular variations in measured canopy temperatures were 4–6°C (azimuth) and 2.5°C (nadir). Maximum angular variations in simulated temperatures using the modified rough surface model was 4°C. The rough surface model appeared to be sensitive to large gaps in the canopy height profile, which influenced the resultant predicted temperature. (author)

  2. Development of partial rock veneers by root throw in a subalpine setting

    Science.gov (United States)

    Osterkamp, W.R.; Toy, T.J.; Lenart, M.T.

    2006-01-01

    Rock veneers stabilize hillslope surfaces, occur especially in areas of immature soil, and form through a variety of process sets that includes root throw. Near Westcliffe, Colorado, USA, data were collected from a 20 ?? 500 m transect on the east slope of the Sangre de Cristo Mountains. Ages of pit/mound complexes with rock fragments exposed at the surface by root throw ranged from recent (freshly toppled tree) to unknown (complete tree decay). Calculations based on dimensions of the pit/mound complexes, estimated time of free topppling, sizes of exposed rock fragments, and percentage rock covers at pit/mound complexes, as well as within the transect area, indicate that recent rates of root throw have resulted in only partial rock veneering since late Pleistocene deglaciation. Weathering of rock fragments prevent development of an extensive rock veneer and causes a balance, achieved within an estimated 700 years, between the rates of rock-fragment exposure by root throw and clast disintegration by chemical reduction. The estimated rate of rock-fragment reduction accounts for part of the fluvial sediment yields observed for forested subalpine areas of western North America. Copyright ?? 2005 John Wiley & Sons, Ltd.

  3. Probabilistic risk models for multiple disturbances: an example of forest insects and wildfires

    Science.gov (United States)

    Haiganoush K. Preisler; Alan A. Ager; Jane L. Hayes

    2010-01-01

    Building probabilistic risk models for highly random forest disturbances like wildfire and forest insect outbreaks is a challenging. Modeling the interactions among natural disturbances is even more difficult. In the case of wildfire and forest insects, we looked at the probability of a large fire given an insect outbreak and also the incidence of insect outbreaks...

  4. Modeling carbon stocks in a secondary tropical dry forest in the Yucatan Peninsula, Mexico

    Science.gov (United States)

    Zhaohua Dai; Richard A. Birdsey; Kristofer D. Johnson; Juan Manuel Dupuy; Jose Luis Hernandez-Stefanoni; Karen. Richardson

    2014-01-01

    The carbon balance of secondary dry tropical forests of Mexico’s Yucatan Peninsula is sensitive to human and natural disturbances and climate change. The spatially explicit process model Forest-DeNitrification-DeComposition (DNDC) was used to estimate forest carbon dynamics in this region, including the effects of disturbance on carbon stocks. Model evaluation using...

  5. Forest product trade impacts of an invasive species: modeling structure and intervention trade-offs

    Science.gov (United States)

    Jeffrey Prestemon; Shushuai Zhu; James A. Turner; Joseph Buongiorno; Ruhong Li

    2006-01-01

    Asian gypsy and nun moth introductions into the United States, possibly arriving on imported Siberian coniferous logs, threaten domestic forests and product markers and could have global market consequences. We simulate, using the Global Forest Products Model (a spatial equilibrium model of the world forest sector), the consequences under current policies of a...

  6. Use of models to study forest fire behavior

    Science.gov (United States)

    Wallace L. Fons

    1961-01-01

    The U.S. Forest Service has started a laboratory study with the ultimate objective of determining model laws for fire behavior. The study includes an examination of the effect of such variables as species of wood, density of wood, moisture content, size of fuel particle, spacing, dimensions of fuel bed, wind, and slope on the rate of spread of fire and the partition of...

  7. Do forest gap model simulations of climate change effects have a catastrophist bias?

    Energy Technology Data Exchange (ETDEWEB)

    LeBlanc, D.C. [Ball State Univ., Muncie, IN (United States). Dept. of Biology; Loehle, C. [Argonne National Lab., IL (United States)

    1997-08-01

    Forest gap simulation models have been widely used to project potential effects of global climate change on forest ecosystems. These projections are given high visibility in governmental and intergovernmental reports that are part of the basis for formulating national and international policy regarding global change. The most recent draft report from the IPCC is but one of many cases where the results from forest gap simulation models have been used as the best available projection of the effects of climate change on forests.

  8. Lidar Remote Sensing of Forests: New Instruments and Modeling Capabilities

    Science.gov (United States)

    Cook, Bruce D.

    2012-01-01

    Lidar instruments provide scientists with the unique opportunity to characterize the 3D structure of forest ecosystems. This information allows us to estimate properties such as wood volume, biomass density, stocking density, canopy cover, and leaf area. Structural information also can be used as drivers for photosynthesis and ecosystem demography models to predict forest growth and carbon sequestration. All lidars use time-in-flight measurements to compute accurate ranging measurements; however, there is a wide range of instruments and data types that are currently available, and instrument technology continues to advance at a rapid pace. This seminar will present new technologies that are in use and under development at NASA for airborne and space-based missions. Opportunities for instrument and data fusion will also be discussed, as Dr. Cook is the PI for G-LiHT, Goddard's LiDAR, Hyperspectral, and Thermal airborne imager. Lastly, this talk will introduce radiative transfer models that can simulate interactions between laser light and forest canopies. Developing modeling capabilities is important for providing continuity between observations made with different lidars, and to assist the design of new instruments. Dr. Bruce Cook is a research scientist in NASA's Biospheric Sciences Laboratory at Goddard Space Flight Center, and has more than 25 years of experience conducting research on ecosystem processes, soil biogeochemistry, and exchange of carbon, water vapor and energy between the terrestrial biosphere and atmosphere. His research interests include the combined use of lidar, hyperspectral, and thermal data for characterizing ecosystem form and function. He is Deputy Project Scientist for the Landsat Data Continuity Mission (LDCM); Project Manager for NASA s Carbon Monitoring System (CMS) pilot project for local-scale forest biomass; and PI of Goddard's LiDAR, Hyperspectral, and Thermal (G-LiHT) airborne imager.

  9. Forest fire forecasting tool for air quality modelling systems

    Energy Technology Data Exchange (ETDEWEB)

    San Jose, R.; Perez, J.L.; Perez, L.; Gonzalez, R.M.; Pecci, J.; Palacios, M.

    2015-07-01

    Adverse effects of smoke on air quality are of great concern; however, even today the estimates of atmospheric fire emissions are a key issue. It is necessary to implement systems for predicting smoke into an air quality modelling system, and in this work a first attempt towards creating a system of this type is presented. Wildland fire spread and behavior are complex Phenomena due to both the number of involved physic-chemical factors, and the nonlinear relationship between variables. WRF-Fire was employed to simulate spread and behavior of some real fires occurred in South-East of Spain and North of Portugal. The use of fire behavior models requires the availability of high resolution environmental and fuel data. A new custom fuel moisture content model has been developed. The new module allows each time step to calculate the fuel moisture content of the dead fuels and live fuels. The results confirm that the use of accurate meteorological data and a custom fuel moisture content model is crucial to obtain precise simulations of fire behavior. To simulate air pollution over Europe, we use the regional meteorological-chemistry transport model WRF-Chem. In this contribution, we show the impact of using two different fire emissions inventories (FINN and IS4FIRES) and how the coupled WRF-FireChem model improves the results of the forest fire emissions and smoke concentrations. The impact of the forest fire emissions on concentrations is evident, and it is quite clear from these simulations that the choice of emission inventory is very important. We conclude that using the WRF-fire behavior model produces better results than using forest fire emission inventories although the requested computational power is much higher. (Author)

  10. Forest fire forecasting tool for air quality modelling systems

    International Nuclear Information System (INIS)

    San Jose, R.; Perez, J.L.; Perez, L.; Gonzalez, R.M.; Pecci, J.; Palacios, M.

    2015-01-01

    Adverse effects of smoke on air quality are of great concern; however, even today the estimates of atmospheric fire emissions are a key issue. It is necessary to implement systems for predicting smoke into an air quality modelling system, and in this work a first attempt towards creating a system of this type is presented. Wildland fire spread and behavior are complex Phenomena due to both the number of involved physic-chemical factors, and the nonlinear relationship between variables. WRF-Fire was employed to simulate spread and behavior of some real fires occurred in South-East of Spain and North of Portugal. The use of fire behavior models requires the availability of high resolution environmental and fuel data. A new custom fuel moisture content model has been developed. The new module allows each time step to calculate the fuel moisture content of the dead fuels and live fuels. The results confirm that the use of accurate meteorological data and a custom fuel moisture content model is crucial to obtain precise simulations of fire behavior. To simulate air pollution over Europe, we use the regional meteorological-chemistry transport model WRF-Chem. In this contribution, we show the impact of using two different fire emissions inventories (FINN and IS4FIRES) and how the coupled WRF-FireChem model improves the results of the forest fire emissions and smoke concentrations. The impact of the forest fire emissions on concentrations is evident, and it is quite clear from these simulations that the choice of emission inventory is very important. We conclude that using the WRF-fire behavior model produces better results than using forest fire emission inventories although the requested computational power is much higher. (Author)

  11. Forest fire forecasting tool for air quality modelling systems

    International Nuclear Information System (INIS)

    San Jose, R.; Perez, J. L.; Perez, L.; Gonzalez, R. M.; Pecci, J.; Palacios, M.

    2015-01-01

    Adverse effects of smoke on air quality are of great concern; however, even today the estimates of atmospheric fire emissions are a key issue. It is necessary to implement systems for predicting smoke into an air quality modelling system, and in this work a first attempt towards creating a system of this type is presented. Wild land fire spread and behavior are complex phenomena due to both the number of involved physic-chemical factors, and the nonlinear relationship between variables. WRF-Fire was employed to simulate spread and behavior of some real fires occurred in South-East of Spain and North of Portugal. The use of fire behavior models requires the availability of high resolution environmental and fuel data. A new custom fuel moisture content model has been developed. The new module allows each time step to calculate the fuel moisture content of the dead fuels and live fuels. The results confirm that the use of accurate meteorological data and a custom fuel moisture content model is crucial to obtain precise simulations of fire behavior. To simulate air pollution over Europe, we use the regional meteorological-chemistry transport model WRF-Chem. In this contribution, we show the impact of using two different fire emissions inventories (FINN and IS4FIRES) and how the coupled WRF-Fire- Chem model improves the results of the forest fire emissions and smoke concentrations. The impact of the forest fire emissions on concentrations is evident, and it is quite clear from these simulations that the choice of emission inventory is very important. We conclude that using the WRF-fire behavior model produces better results than using forest fire emission inventories although the requested computational power is much higher. (Author)

  12. Forest fire forecasting tool for air quality modelling systems

    Energy Technology Data Exchange (ETDEWEB)

    San Jose, R.; Perez, J. L.; Perez, L.; Gonzalez, R. M.; Pecci, J.; Palacios, M.

    2015-07-01

    Adverse effects of smoke on air quality are of great concern; however, even today the estimates of atmospheric fire emissions are a key issue. It is necessary to implement systems for predicting smoke into an air quality modelling system, and in this work a first attempt towards creating a system of this type is presented. Wild land fire spread and behavior are complex phenomena due to both the number of involved physic-chemical factors, and the nonlinear relationship between variables. WRF-Fire was employed to simulate spread and behavior of some real fires occurred in South-East of Spain and North of Portugal. The use of fire behavior models requires the availability of high resolution environmental and fuel data. A new custom fuel moisture content model has been developed. The new module allows each time step to calculate the fuel moisture content of the dead fuels and live fuels. The results confirm that the use of accurate meteorological data and a custom fuel moisture content model is crucial to obtain precise simulations of fire behavior. To simulate air pollution over Europe, we use the regional meteorological-chemistry transport model WRF-Chem. In this contribution, we show the impact of using two different fire emissions inventories (FINN and IS4FIRES) and how the coupled WRF-Fire- Chem model improves the results of the forest fire emissions and smoke concentrations. The impact of the forest fire emissions on concentrations is evident, and it is quite clear from these simulations that the choice of emission inventory is very important. We conclude that using the WRF-fire behavior model produces better results than using forest fire emission inventories although the requested computational power is much higher. (Author)

  13. Adapting an IPCC-Compliant Full Forest Carbon Accounting Model to Determine the Effects of Different Forest Management Strategies in California

    Science.gov (United States)

    Starrs, C.; Stewart, W.; Potts, M. D.

    2016-12-01

    As California experiences increasing rates of disturbance events such as wildfire, drought, and insect outbreaks, understanding how different management strategies affect long-term forest carbon stock changes in the forest and in harvested wood products used by society will be key to determining strategies to best maximize forest-related carbon sequestration in the future. California's forest area is roughly evenly split across three ownership types: private timberlands, National Forest timberlands, and reserved forests. Forest management strategies in California generally vary by these ownerships; management in reserved lands sequesters carbon within the forest (i.e. leaves wood in the forest), while on private and National Forest timberlands a significant amount of wood is removed from the forest and converted to harvested wood products. The Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) is an IPCC-compliant full forest carbon accounting model developed for use in Canada that has been adapted for use in other countries. Changes in natural disturbances in the forest and technological innovation in the use of harvested wood products could substantially alter future carbon trajectories of forests under different management regimes. A key advantage of the CBM-CFS3 model is that in addition to tracking live tree, dead tree, and dead organic matter (DOM) carbon pools in the forest, it also tracks carbon stock changes in harvested wood products. We calibrated the CBM-CFS3 model with US Forest Service Forest Inventory and Analysis (FIA) data for seven forest types across three ownership types to predict carbon stock changes under different natural disturbance and harvested wood product utilization futures. Our results illustrate the importance of using a tractable model that can integrate future changes in forest carbon cycling to keep pace with our changing climate and usage of wood products.

  14. The Chemistry of Atmosphere-Forest Exchange (CAFE Model – Part 1: Model description and characterization

    Directory of Open Access Journals (Sweden)

    G. M. Wolfe

    2011-01-01

    Full Text Available We present the Chemistry of Atmosphere-Forest Exchange (CAFE model, a vertically-resolved 1-D chemical transport model designed to probe the details of near-surface reactive gas exchange. CAFE integrates all key processes, including turbulent diffusion, emission, deposition and chemistry, throughout the forest canopy and mixed layer. CAFE utilizes the Master Chemical Mechanism (MCM and is the first model of its kind to incorporate a suite of reactions for the oxidation of monoterpenes and sesquiterpenes, providing a more comprehensive description of the oxidative chemistry occurring within and above the forest. We use CAFE to simulate a young Ponderosa pine forest in the Sierra Nevada, CA. Utilizing meteorological constraints from the BEARPEX-2007 field campaign, we assess the sensitivity of modeled fluxes to parameterizations of diffusion, laminar sublayer resistance and radiation extinction. To characterize the general chemical environment of this forest, we also present modeled mixing ratio profiles of biogenic hydrocarbons, hydrogen oxides and reactive nitrogen. The vertical profiles of these species demonstrate a range of structures and gradients that reflect the interplay of physical and chemical processes within the forest canopy, which can influence net exchange.

  15. Toward trait-based mortality models for tropical forests.

    Directory of Open Access Journals (Sweden)

    Mélaine Aubry-Kientz

    Full Text Available Tree mortality in tropical forests is a complex ecological process for which modelling approaches need to be improved to better understand, and then predict, the evolution of tree mortality in response to global change. The mortality model introduced here computes an individual probability of dying for each tree in a community. The mortality model uses the ontogenetic stage of the tree because youngest and oldest trees are more likely to die. Functional traits are integrated as proxies of the ecological strategies of the trees to permit generalization among all species in the community. Data used to parametrize the model were collected at Paracou study site, a tropical rain forest in French Guiana, where 20,408 trees have been censused for 18 years. A Bayesian framework was used to select useful covariates and to estimate the model parameters. This framework was developed to deal with sources of uncertainty, including the complexity of the mortality process itself and the field data, especially historical data for which taxonomic determinations were uncertain. Uncertainty about the functional traits was also considered, to maximize the information they contain. Four functional traits were strong predictors of tree mortality: wood density, maximum height, laminar toughness and stem and branch orientation, which together distinguished the light-demanding, fast-growing trees from slow-growing trees with lower mortality rates. Our modelling approach formalizes a complex ecological problem and offers a relevant mathematical framework for tropical ecologists to process similar uncertain data at the community level.

  16. Toward trait-based mortality models for tropical forests.

    Science.gov (United States)

    Aubry-Kientz, Mélaine; Hérault, Bruno; Ayotte-Trépanier, Charles; Baraloto, Christopher; Rossi, Vivien

    2013-01-01

    Tree mortality in tropical forests is a complex ecological process for which modelling approaches need to be improved to better understand, and then predict, the evolution of tree mortality in response to global change. The mortality model introduced here computes an individual probability of dying for each tree in a community. The mortality model uses the ontogenetic stage of the tree because youngest and oldest trees are more likely to die. Functional traits are integrated as proxies of the ecological strategies of the trees to permit generalization among all species in the community. Data used to parametrize the model were collected at Paracou study site, a tropical rain forest in French Guiana, where 20,408 trees have been censused for 18 years. A Bayesian framework was used to select useful covariates and to estimate the model parameters. This framework was developed to deal with sources of uncertainty, including the complexity of the mortality process itself and the field data, especially historical data for which taxonomic determinations were uncertain. Uncertainty about the functional traits was also considered, to maximize the information they contain. Four functional traits were strong predictors of tree mortality: wood density, maximum height, laminar toughness and stem and branch orientation, which together distinguished the light-demanding, fast-growing trees from slow-growing trees with lower mortality rates. Our modelling approach formalizes a complex ecological problem and offers a relevant mathematical framework for tropical ecologists to process similar uncertain data at the community level.

  17. Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Saleska, Scott [Univ. of Arizona, Tucson, AZ (United States); Davidson, Eric [Univ. of Arizona, Tucson, AZ (United States); Finzi, Adrien [Univ. of Arizona, Tucson, AZ (United States); Wehr, Richard [Univ. of Arizona, Tucson, AZ (United States); Moorcroft, Paul [Univ. of Arizona, Tucson, AZ (United States)

    2016-01-28

    photosynthesis (by ~25%) and daytime respiration (by ~100%) in the first half of the growing season at our site, and portrays ecosystem photosynthetic light-use efficiency as declining when in fact it is stable until autumnal senescence. B. Vegetation Phenology and belowground allocation: Findings: 1. Autotrophic respiration (Ra) showed a seasonal pattern, peaking in mid-summer when trees were most active. 2. The effective age of the substrate for belowground respiration is less than 2 weeks. 3. Above and belowground phenology are more synchronous in deciduous hardwood stands than evergreen hemlock stands. 4. The decline in root respiration rates in the fall is related to temperature rather than acclimation of root respiration or substrate limitations. Methodological Issues: 5. The isotopic signatures of autotrophic and heterotrophic respiration are too similar for isotopic partitioning of belowground respiration into these two components at our site—in keeping with the recent findings of Bowling et al. (2015) in a subalpine conifer forest. 6. Artifacts of the trenching method, such as changes in soil moisture and increased carbon substrate from the newly severed roots, are significant and need to be quantified when determining daily to annual estimates of autotrophic and heterotrophic respiration. C. Effects of simulated exudates on priming of microbial decomposition: The stoichiometry of root exudates influences both the amount and the mechanism by which priming occurs. At low C:N, SOC loss is caused by an increase in microbial efficiency. At high C:N, SOC loss is caused by an increase in microbial biomass. D. Modeling with the Ecosystem Demography Model (ED2): 1. Incorporation of 13C tracking to create an isotopically-enabled Ecosystem Demography v2 model (ED2) 2. State-of-the-art parameter optimization methodology developed for improving ED2 model predictions and parameters. 3. Significantly improved model predictions of growth- and maintenance-related carbon fluxes and 13

  18. Distribution patterns and environmental correlates of Thaumarchaeota abundance in six deep subalpine lakes.

    Czech Academy of Sciences Publication Activity Database

    Callieri, C.; Hernandez-Aviles, S.; Salcher, Michaela M.; Fontaneto, D.; Bertoni, R.

    2016-01-01

    Roč. 78, č. 2 (2016), s. 215-225 ISSN 1015-1621 Institutional support: RVO:60077344 Keywords : subalpine lakes * Thaumarchaeota vertical profile * CARD FISH * hypolimnion Subject RIV: EE - Microbiology, Virology Impact factor: 2.821, year: 2016

  19. Rapid warming forces contrasting growth trends of subalpine fir ( Abies fabri ) at higher- and lower-elevations in the eastern Tibetan Plateau

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenzhi; Jia, Min; Wang, Genxu; Zhu, Wanze; McDowell, Nate G.

    2017-10-01

    Tree radial growth is expected to increase at higher elevations under climate warming, while lower elevation tree growth is expected to decline. However, numerous studies have found tree radial growth responds consistently to climate along elevational gradients. Here, we sampled five plots across the subalpine Abies fabri forest belt on Gongga Mountain in the eastern Tibetan Plateau to determine tree radial growth trends and responses to climate. Three commonly used detrending methods all consistently showed that tree radial growth at high elevation (> 3100 m) increased, while tree growth declined at the lower elevations (2700 m–2900 m) over the last three decades. Increasing late-growing season temperature positively (p < 0.05) correlated to tree radial growth at higher elevations, but the sign of this relationship reversed to become negative at lower elevations. Moving-window correlation analyses indicated the difference between high and low elevations response to temperature variation increased strongly with warming. Placing our result into the global context, 62% of 39 published studies found that trees along elevation gradients respond divergently to warming, and that these are located in warmer and wetter regions of the Earth. Notably, 28% of studies found non-significant responses to temperature at both high and low elevations. Our findings in the subalpine mountain forest in the eastern Tibetan Plateau were consistent with the majority of published datasets, and imply increasing temperature benefit for tree populations at higher elevation, while warming dampens growth at lower elevations.

  20. Adapting the Water Erosion Prediction Project (WEPP) model for forest applications

    Science.gov (United States)

    Shuhui Dun; Joan Q. Wu; William J. Elliot; Peter R. Robichaud; Dennis C. Flanagan; James R. Frankenberger; Robert E. Brown; Arthur C. Xu

    2009-01-01

    There has been an increasing public concern over forest stream pollution by excessive sedimentation due to natural or human disturbances. Adequate erosion simulation tools are needed for sound management of forest resources. The Water Erosion Prediction Project (WEPP) watershed model has proved useful in forest applications where Hortonian flow is the major form of...

  1. Fuel load modeling from mensuration attributes in temperate forests in northern Mexico

    Science.gov (United States)

    Maricela Morales-Soto; Marín Pompa-Garcia

    2013-01-01

    The study of fuels is an important factor in defining the vulnerability of ecosystems to forest fires. The aim of this study was to model a dead fuel load based on forest mensuration attributes from forest management inventories. A scatter plot analysis was performed and, from explanatory trends between the variables considered, correlation analysis was carried out...

  2. Recent findings related to measuring and modeling forest road erosion

    Science.gov (United States)

    W. J. Elliot; R. B. Foltz; P. R. Robichaud

    2009-01-01

    Sediment is the greatest pollutant of forest streams. In the absence of wildfire, forest road networks are usually the main source of sediment in forest watersheds. An understanding of forest road erosion processes is important to aid in predicting sediment delivery from roads to streams. The flowpath followed by runoff is the key to understanding road erosion...

  3. Sequential fragmentation of Pleistocene forests in an East Africa biodiversity hotspot: chameleons as a model to track forest history.

    Directory of Open Access Journals (Sweden)

    G John Measey

    Full Text Available The Eastern Arc Mountains (EAM is an example of naturally fragmented tropical forests, which contain one of the highest known concentrations of endemic plants and vertebrates. Numerous paleo-climatic studies have not provided direct evidence for ancient presence of Pleistocene forests, particularly in the regions in which savannah presently occurs. Knowledge of the last period when forests connected EAM would provide a sound basis for hypothesis testing of vicariance and dispersal models of speciation. Dated phylogenies have revealed complex patterns throughout EAM, so we investigated divergence times of forest fauna on four montane isolates in close proximity to determine whether forest break-up was most likely to have been simultaneous or sequential, using population genetics of a forest restricted arboreal chameleon, Kinyongia boehmei.We used mitochondrial and nuclear genetic sequence data and mutation rates from a fossil-calibrated phylogeny to estimate divergence times between montane isolates using a coalescent approach. We found that chameleons on all mountains are most likely to have diverged sequentially within the Pleistocene from 0.93-0.59 Ma (95% HPD 0.22-1.84 Ma. In addition, post-hoc tests on chameleons on the largest montane isolate suggest a population expansion ∼182 Ka.Sequential divergence is most likely to have occurred after the last of three wet periods within the arid Plio-Pleistocene era, but was not correlated with inter-montane distance. We speculate that forest connection persisted due to riparian corridors regardless of proximity, highlighting their importance in the region's historic dispersal events. The population expansion coincides with nearby volcanic activity, which may also explain the relative paucity of the Taita's endemic fauna. Our study shows that forest chameleons are an apposite group to track forest fragmentation, with the inference that forest extended between some EAM during the Pleistocene 1

  4. Sequential fragmentation of Pleistocene forests in an East Africa biodiversity hotspot: chameleons as a model to track forest history.

    Science.gov (United States)

    Measey, G John; Tolley, Krystal A

    2011-01-01

    The Eastern Arc Mountains (EAM) is an example of naturally fragmented tropical forests, which contain one of the highest known concentrations of endemic plants and vertebrates. Numerous paleo-climatic studies have not provided direct evidence for ancient presence of Pleistocene forests, particularly in the regions in which savannah presently occurs. Knowledge of the last period when forests connected EAM would provide a sound basis for hypothesis testing of vicariance and dispersal models of speciation. Dated phylogenies have revealed complex patterns throughout EAM, so we investigated divergence times of forest fauna on four montane isolates in close proximity to determine whether forest break-up was most likely to have been simultaneous or sequential, using population genetics of a forest restricted arboreal chameleon, Kinyongia boehmei. We used mitochondrial and nuclear genetic sequence data and mutation rates from a fossil-calibrated phylogeny to estimate divergence times between montane isolates using a coalescent approach. We found that chameleons on all mountains are most likely to have diverged sequentially within the Pleistocene from 0.93-0.59 Ma (95% HPD 0.22-1.84 Ma). In addition, post-hoc tests on chameleons on the largest montane isolate suggest a population expansion ∼182 Ka. Sequential divergence is most likely to have occurred after the last of three wet periods within the arid Plio-Pleistocene era, but was not correlated with inter-montane distance. We speculate that forest connection persisted due to riparian corridors regardless of proximity, highlighting their importance in the region's historic dispersal events. The population expansion coincides with nearby volcanic activity, which may also explain the relative paucity of the Taita's endemic fauna. Our study shows that forest chameleons are an apposite group to track forest fragmentation, with the inference that forest extended between some EAM during the Pleistocene 1.1-0.9 Ma.

  5. Sequential Fragmentation of Pleistocene Forests in an East Africa Biodiversity Hotspot: Chameleons as a Model to Track Forest History

    Science.gov (United States)

    Measey, G. John; Tolley, Krystal A.

    2011-01-01

    Background The Eastern Arc Mountains (EAM) is an example of naturally fragmented tropical forests, which contain one of the highest known concentrations of endemic plants and vertebrates. Numerous paleo-climatic studies have not provided direct evidence for ancient presence of Pleistocene forests, particularly in the regions in which savannah presently occurs. Knowledge of the last period when forests connected EAM would provide a sound basis for hypothesis testing of vicariance and dispersal models of speciation. Dated phylogenies have revealed complex patterns throughout EAM, so we investigated divergence times of forest fauna on four montane isolates in close proximity to determine whether forest break-up was most likely to have been simultaneous or sequential, using population genetics of a forest restricted arboreal chameleon, Kinyongia boehmei. Methodology/Principal Findings We used mitochondrial and nuclear genetic sequence data and mutation rates from a fossil-calibrated phylogeny to estimate divergence times between montane isolates using a coalescent approach. We found that chameleons on all mountains are most likely to have diverged sequentially within the Pleistocene from 0.93–0.59 Ma (95% HPD 0.22–1.84 Ma). In addition, post-hoc tests on chameleons on the largest montane isolate suggest a population expansion ∼182 Ka. Conclusions/Significance Sequential divergence is most likely to have occurred after the last of three wet periods within the arid Plio-Pleistocene era, but was not correlated with inter-montane distance. We speculate that forest connection persisted due to riparian corridors regardless of proximity, highlighting their importance in the region's historic dispersal events. The population expansion coincides with nearby volcanic activity, which may also explain the relative paucity of the Taita's endemic fauna. Our study shows that forest chameleons are an apposite group to track forest fragmentation, with the inference that forest

  6. Model design to predict forest fire risk in Navarra (Spain) using time series analysis

    OpenAIRE

    Huesca, M.; Litago, J.; Palacios-Orueta, A.; Merino de Miguel, Silvia

    2008-01-01

    Understand and predict how forest fire potential changes over time are essential for prioritizing forest management activities and reducing damage. Nowadays we lack the capacity to predict future forest fire trends in response to climate change. The main goal of this research is to build an empirical model to describe, estimate and forecast the forest fires dynamics using the improved Fire Potential Index (FPI) (Huesca et al., 2007) as indicator of fire.

  7. Carbon dynamics in the future forest: the importance of long-term successional legacy and climate-fire interactions.

    Science.gov (United States)

    Loudermilk, E Louise; Scheller, Robert M; Weisberg, Peter J; Yang, Jian; Dilts, Thomas E; Karam, Sarah L; Skinner, Carl

    2013-11-01

    Understanding how climate change may influence forest carbon (C) budgets requires knowledge of forest growth relationships with regional climate, long-term forest succession, and past and future disturbances, such as wildfires and timber harvesting events. We used a landscape-scale model of forest succession, wildfire, and C dynamics (LANDIS-II) to evaluate the effects of a changing climate (A2 and B1 IPCC emissions; Geophysical Fluid Dynamics Laboratory General Circulation Models) on total forest C, tree species composition, and wildfire dynamics in the Lake Tahoe Basin, California, and Nevada. The independent effects of temperature and precipitation were assessed within and among climate models. Results highlight the importance of modeling forest succession and stand development processes at the landscape scale for understanding the C cycle. Due primarily to landscape legacy effects of historic logging of the Comstock Era in the late 1880s, C sequestration may continue throughout the current century, and the forest will remain a C sink (Net Ecosystem Carbon Balance > 0), regardless of climate regime. Climate change caused increases in temperatures limited simulated C sequestration potential because of augmented fire activity and reduced establishment ability of subalpine and upper montane trees. Higher temperatures influenced forest response more than reduced precipitation. As the forest reached its potential steady state, the forest could become C neutral or a C source, and climate change could accelerate this transition. The future of forest ecosystem C cycling in many forested systems worldwide may depend more on major disturbances and landscape legacies related to land use than on projected climate change alone. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  8. Modeling future U.S. forest sector market and trade impacts of expansion in wood energy consumption

    Science.gov (United States)

    Peter J. Ince; Andrew D. Kramp; Kenneth E. Skog; Do-il Yoo; V. Alaric Sample

    2011-01-01

    This paper describes an approach to modeling U.S. forest sector market and trade impacts of expansion in domestic wood energy consumption under hypothetical future U.S. wood biomass energy policy scenarios. The U.S. Forest Products Module (USFPM) was created to enhance the modeling of the U.S. forest sector within the Global Forest Products Model (GFPM), providing a...

  9. Comparison of two canopy reflectance models inversion for mapping forest crown closure using imaging spectroscopy

    NARCIS (Netherlands)

    Zeng, Y.; Schaepman, M.E.; Huang, H.A.; Bruin, de S.; Clevers, J.G.P.W.

    2008-01-01

    We compare the inversion of two canopy reflectance models to estimate forest crown closure (CC) using an EO-1 Hyperion image: the Kuusk¿Nilson forest reflectance and transmittance (FRT) model, and the Li¿Strahler geometric¿optical model. For predicting CC on a per-pixel basis, the FRT model

  10. Application of GIS to Empirical Windthrow Risk Model in Mountain Forested Landscapes

    Directory of Open Access Journals (Sweden)

    Lukas Krejci

    2018-02-01

    Full Text Available Norway spruce dominates mountain forests in Europe. Natural variations in the mountainous coniferous forests are strongly influenced by all the main components of forest and landscape dynamics: species diversity, the structure of forest stands, nutrient cycling, carbon storage, and other ecosystem services. This paper deals with an empirical windthrow risk model based on the integration of logistic regression into GIS to assess forest vulnerability to wind-disturbance in the mountain spruce forests of Šumava National Park (Czech Republic. It is an area where forest management has been the focus of international discussions by conservationists, forest managers, and stakeholders. The authors developed the empirical windthrow risk model, which involves designing an optimized data structure containing dependent and independent variables entering logistic regression. The results from the model, visualized in the form of map outputs, outline the probability of risk to forest stands from wind in the examined territory of the national park. Such an application of the empirical windthrow risk model could be used as a decision support tool for the mountain spruce forests in a study area. Future development of these models could be useful for other protected European mountain forests dominated by Norway spruce.

  11. Assessing the Impact of Forest Change and Climate Variability on Dry Season Runoff by an Improved Single Watershed Approach: A Comparative Study in Two Large Watersheds, China

    Directory of Open Access Journals (Sweden)

    Yiping Hou

    2018-01-01

    Full Text Available Extensive studies on hydrological responses to forest change have been published for centuries, yet partitioning the hydrological effects of forest change, climate variability and other factors in a large watershed remains a challenge. In this study, we developed a single watershed approach combining the modified double mass curve (MDMC and the time series multivariate autoregressive integrated moving average model (ARIMAX to separate the impact of forest change, climate variability and other factors on dry season runoff variation in two large watersheds in China. The Zagunao watershed was examined for the deforestation effect, while the Meijiang watershed was examined to study the hydrological impact of reforestation. The key findings are: (1 both deforestation and reforestation led to significant reductions in dry season runoff, while climate variability yielded positive effects in the studied watersheds; (2 the hydrological response to forest change varied over time due to changes in soil infiltration and evapotranspiration after vegetation regeneration; (3 changes of subalpine natural forests produced greater impact on dry season runoff than alteration of planted forests. These findings are beneficial to water resource and forest management under climate change and highlight a better planning of forest operations and management incorporated trade-off between carbon and water in different forests.

  12. Interferometric SAR Coherence Models for Characterization of Hemiboreal Forests Using TanDEM-X Data

    Directory of Open Access Journals (Sweden)

    Aire Olesk

    2016-08-01

    Full Text Available In this study, four models describing the interferometric coherence of the forest vegetation layer are proposed and compared with the TanDEM-X data. Our focus is on developing tools for hemiboreal forest height estimation from single-pol interferometric SAR measurements, suitable for wide area forest mapping with limited a priori information. The multi-temporal set of 19 TanDEM-X interferometric pairs and the 90th percentile forest height maps are derived from Airborne LiDAR Scanning (ALS, covering an area of 2211 ha of forests over Estonia. Three semi-empirical models along with the Random Volume over Ground (RVoG model are examined for applicable parameter ranges and model performance under various conditions for over 3000 forest stands. This study shows that all four models performed well in describing the relationship between forest height and interferometric coherence. Use of an advanced model with multiple parameters is not always justified when modeling the volume decorrelation in the boreal and hemiboreal forests. The proposed set of semi-empirical models, show higher robustness compared to a more advanced RVoG model under a range of seasonal and environmental conditions during data acquisition. We also examine the dynamic range of parameters that different models can take and propose optimal conditions for forest stand height inversion for operationally-feasible scenarios.

  13. Remote Sensing Protocols for Parameterizing an Individual, Tree-Based, Forest Growth and Yield Model

    Science.gov (United States)

    2014-09-01

    Penelope Morgan. 2006. “Regression Modeling and Mapping of Coniferous Forest Basal Area and Tree Density from Discrete- Return LIDAR and... Basal Area Relationships of Open-Grown Southern Pines for Modeling Competition and Growth.” Canadian Journal of of Forest Research 22: 341–347... Forest Growth and Yield Model Co ns tr uc tio n En gi ne er in g R es ea rc h La bo ra to ry Scott A. Tweddale, Patrick J. Guertin, and

  14. Geotechnology-Based Modeling to Optimize Conservation of Forest Network in Urban Area

    Science.gov (United States)

    Teng, Mingjun; Zhou, Zhixiang; Wang, Pengcheng; Xiao, Wenfa; Wu, Changguang; Lord, Elizabeth

    2016-03-01

    Forest network development in urban areas faces the challenge from forest fragmentation, human-induced disturbances, and scarce land resources. Here, we proposed a geotechnology-based modeling to optimize conservation of forest network by a case study of Wuhan, China. The potential forest network and their priorities were assessed using an improved least-cost path model and potential utilization efficiency estimation. The modeling process consists of four steps: (i) developing species assemblages, (ii) identifying core forest patches, (iii) identifying potential linkages among core forest patches, and (iv) demarcating forest networks. As a result, three species assemblages, including mammals, pheasants, and other birds, were identified as the conservation targets of urban forest network (UFN) in Wuhan, China. Based on the geotechnology-based model, a forest network proposal was proposed to fulfill the connectivity requirements of selected species assemblages. The proposal consists of seven forest networks at three levels of connectivity, named ideal networks, backbone networks, and comprehensive network. The action priorities of UFN plans were suggested to optimize forest network in the study area. Additionally, a total of 45 forest patches with important conservation significance were identified as prioritized stepping-stone patches in the forest network development. Urban forest conserve was also suggested for preserving woodlands with priority conservation significance. The presented geotechnology-based modeling is fit for planning and optimizing UFNs, because of the inclusion of the stepping-stone effects, human-induced pressures, and priorities. The framework can also be applied to other areas after a sensitivity test of the model and the modification of the parameters to fit the local environment.

  15. Forest insurance market participants’ game behavior in China: An analysis based on tripartite dynamic game model

    Directory of Open Access Journals (Sweden)

    Ning Ma

    2015-11-01

    Full Text Available Purpose: In forest insurance market, there are three main participants including the insurance company, the forest farmer and the government. As different participant has different benefit object, there will be a complex and dynamic game relationship among all participants. The purpose of this paper is to make the game relationship among all participants in forest insurance market clear, and then to put forward some policy suggestions on the implementation of forest insurance from the view of game theory. Design/methodology/approach: Firstly, the static game model between the insurance company and the forest farmer is set up. According to the result of static game model, it’s difficult to implement forest insurance without government. Secondly, the tripartite dynamic game model among the government, the insurance company and the forest farmer is proposed, and the equilibrium solution of tripartite dynamic game model is acquired. Finally, the behavioral characteristics of all participants are analyzed according to the equilibrium solution of tripartite dynamic game model. Findings: the government’s allowance will be an important positive factor to implement forest insurance. The loss of the insurance company, which the lower insurance premium brings, can be compensated by the allowance from the government. The more the government provides allowance, the more actively the insurance company will implement forest insurance at a low insurance premium. In this situation, the forest farmer will be more likely to purchase the forest insurance, then the scope of forest insurance implementation will expend. Originality/value: There is a complex and dynamic game relationship among all participants in forest insurance market. Based on the tripartite dynamic game model, to make the game relationship between each participant clear is conducive to the implementation of forest insurance market in China.

  16. Consequences of increasing bioenergy demand on wood and forests: An application of the Global Forest Products Model

    Science.gov (United States)

    Buongiorno, J.; Raunikar, R.; Zhu, S.

    2011-01-01

    The Global Forest Products Model (GFPM) was applied to project the consequences for the global forest sector of doubling the rate of growth of bioenergy demand relative to a base scenario, other drivers being maintained constant. The results showed that this would lead to the convergence of the price of fuelwood and industrial roundwood, raising the price of industrial roundwood by nearly 30% in 2030. The price of sawnwood and panels would be 15% higher. The price of paper would be 3% higher. Concurrently, the demand for all manufactured wood products would be lower in all countries, but the production would rise in countries with competitive advantage. The global value added in wood processing industries would be 1% lower in 2030. The forest stock would be 2% lower for the world and 4% lower for Asia. These effects varied substantially by country. ?? 2011 Department of Forest Economics, SLU Ume??, Sweden.

  17. Climate change and tree-line ecosystems in the Sierra Nevada: Habitat suitability modelling to inform high-elevation forest dynamics monitoring

    Science.gov (United States)

    Moore, Peggy E.; Alvarez, Otto; McKinney, Shawn T.; Li, Wenkai; Brooks, Matthew L.; Guo, Qinghua

    2017-01-01

    Whitebark pine and foxtail pine serve foundational roles in the subalpine zone of the Sierra Nevada. They provide the dominant structure in tree-line forests and regulate key ecosystem processes and community dynamics. Climate change models suggest that there will be changes in temperature regimes and in the timing and magnitude of precipitation within the current distribution of these species, and these changes may alter the species’ distributional limits. Other stressors include the non-native pathogen white pine blister rust and mountain pine beetle, which have played a role in the decline of whitebark pine throughout much of its range. The National Park Service is monitoring status and trends of these species. This report provides complementary information in the form of habitat suitability models to predict climate change impacts on the future distribution of these species within Sierra Nevada national parks.We used maximum entropy modeling to build habitat suitability models by relating species occurrence to environmental variables. Species occurrence was available from 328 locations for whitebark pine and 244 for foxtail pine across the species’ distributions within the parks. We constructed current climate surfaces for modeling by interpolating data from weather stations. Climate surfaces included mean, minimum, and maximum temperature and total precipitation for January, April, July, and October. We downscaled five general circulation models for the 2050s and the 2090s from ~125 km2 to 1 km2 under both an optimistic and an extreme climate scenario to bracket potential climatic change and its influence on projected suitable habitat. To describe anticipated changes in the distribution of suitable habitat, we compared, for each species, climate scenario, and time period, the current models with future models in terms of proportional change in habitat size, elevation distribution, model center points, and where habitat is predicted to expand or contract

  18. Modelling of radionuclide transport in forests: Review and future perspectives

    International Nuclear Information System (INIS)

    Shaw, G.; Schell, W.; Linkov, I.

    1997-01-01

    Ecological modeling is a powerful tool which can be used to synthesize information on the dynamic processes which occur in ecosystems. Models of radionuclide transport in forests were first constructed in the mid-1960's, when the consequences of global fallout from nuclear weapons tests and waste disposal in the environment were of great concern. Such models were developed based on site-specific experimental data and were designed to address local needs. These models had a limited applicability in evaluating distinct ecosystems and deposition scenarios. Given the scarcity of information, the same experimental data sets were often used both for model calibration and validation, an approach which clearly constitutes a methodological error. Even though the carry modeling attempts were far from being faultless, they established a useful conceptual approach in that they tried to capture general processes in ecosystems and thus had a holistic nature. Later, radioecological modeling attempted to reveal ecosystem properties by separating the component parts from the whole system, as an approach to simplification. This method worked well for radionuclide transport in agricultural ecosystems, in which the biogeochemistry of radionuclide cycling is relatively well understood and can be influenced by fertilization. Several models have been successfully developed and applied to human dose evaluation and emergency response to contaminating events in agricultural lands

  19. An object-oriented forest landscape model and its representation of tree species

    Science.gov (United States)

    Hong S. He; David J. Mladenoff; Joel Boeder

    1999-01-01

    LANDIS is a forest landscape model that simulates the interaction of large landscape processes and forest successional dynamics at tree species level. We discuss how object-oriented design (OOD) approaches such as modularity, abstraction and encapsulation are integrated into the design of LANDIS. We show that using OOD approaches, model decisions (olden as model...

  20. Analyzing the ecosystem carbon and hydrologic characteristics of forested wetland using a biogeochemical process model

    Science.gov (United States)

    Jianbo Cui; Changsheng Li; Carl Trettin

    2005-01-01

    A comprehensive biogeochemical model, Wetland-DNDC, was applied to analyze the carbon and hydrologic characteristics of forested wetland ecosystem at Minnesota (MN) and Florida (FL) sites. The model simulates the flows of carbon, energy, and water in forested wetlands. Modeled carbon dynamics depends on physiological plant factors, the size of plant pools,...

  1. Tree biomass in the Swiss landscape: nationwide modelling for improved accounting for forest and non-forest trees.

    Science.gov (United States)

    Price, B; Gomez, A; Mathys, L; Gardi, O; Schellenberger, A; Ginzler, C; Thürig, E

    2017-03-01

    Trees outside forest (TOF) can perform a variety of social, economic and ecological functions including carbon sequestration. However, detailed quantification of tree biomass is usually limited to forest areas. Taking advantage of structural information available from stereo aerial imagery and airborne laser scanning (ALS), this research models tree biomass using national forest inventory data and linear least-square regression and applies the model both inside and outside of forest to create a nationwide model for tree biomass (above ground and below ground). Validation of the tree biomass model against TOF data within settlement areas shows relatively low model performance (R 2 of 0.44) but still a considerable improvement on current biomass estimates used for greenhouse gas inventory and carbon accounting. We demonstrate an efficient and easily implementable approach to modelling tree biomass across a large heterogeneous nationwide area. The model offers significant opportunity for improved estimates on land use combination categories (CC) where tree biomass has either not been included or only roughly estimated until now. The ALS biomass model also offers the advantage of providing greater spatial resolution and greater within CC spatial variability compared to the current nationwide estimates.

  2. Errors in terrain-based model preditions caused by altered forest inventory plot locations in the Southern Appalachian Mountains, USA.

    Science.gov (United States)

    Huei-Jin Wang; Stephen Prisley; Philip Radtke; John Coulston

    2012-01-01

    Forest modeling applications that cover large geographic area can benefit from the use of widely-held knowledge about relationships between forest attributes and topographic variables. A noteworthy example involved the coupling of field survey data from the Forest Inventory Analysis (FIA) program of USDA Forest Service with digital elevation model (DEM) data in...

  3. Forest evaporation models: Relationships between stand growth and evaporation

    CSIR Research Space (South Africa)

    Le Maitre, David C

    1997-06-01

    Full Text Available The relationships between forest stand structure, growth and evaporation were analysed to determine whether forest evaporation can be estimated from stand growth data. This approach permits rapid assessment of the potential impacts of afforestation...

  4. Modelling of excess noise attnuation by grass and forest | Onuu ...

    African Journals Online (AJOL)

    , guinea grass (panicum maximum) and forest which comprises iroko (milicia ezcelea) and white afara (terminalia superba) trees in the ratio of 2:1 approximately. Excess noise attenuation spectra have been plotted for the grass and forest for ...

  5. The cascade of uncertainty in modeling the impacts of climate change on Europe's forests

    Science.gov (United States)

    Reyer, Christopher; Lasch-Born, Petra; Suckow, Felicitas; Gutsch, Martin

    2015-04-01

    Projecting the impacts of global change on forest ecosystems is a cornerstone for designing sustainable forest management strategies and paramount for assessing the potential of Europe's forest to contribute to the EU bioeconomy. Research on climate change impacts on forests relies to a large extent on model applications along a model chain from Integrated Assessment Models to General and Regional Circulation Models that provide important driving variables for forest models. Or to decision support systems that synthesize findings of more detailed forest models to inform forest managers. At each step in the model chain, model-specific uncertainties about, amongst others, parameter values, input data or model structure accumulate, leading to a cascade of uncertainty. For example, climate change impacts on forests strongly depend on the in- or exclusion of CO2-effects or on the use of an ensemble of climate models rather than relying on one particular climate model. In the past, these uncertainties have not or only partly been considered in studies of climate change impacts on forests. This has left managers and decision-makers in doubt of how robust the projected impacts on forest ecosystems are. We deal with this cascade of uncertainty in a structured way and the objective of this presentation is to assess how different types of uncertainties affect projections of the effects of climate change on forest ecosystems. To address this objective we synthesized a large body of scientific literature on modeled productivity changes and the effects of extreme events on plant processes. Furthermore, we apply the process-based forest growth model 4C to forest stands all over Europe and assess how different climate models, emission scenarios and assumptions about the parameters and structure of 4C affect the uncertainty of the model projections. We show that there are consistent regional changes in forest productivity such as an increase in NPP in cold and wet regions while

  6. FOREST ECOLOGY. Pervasive drought legacies in forest ecosystems and their implications for carbon cycle models.

    Science.gov (United States)

    Anderegg, W R L; Schwalm, C; Biondi, F; Camarero, J J; Koch, G; Litvak, M; Ogle, K; Shaw, J D; Shevliakova, E; Williams, A P; Wolf, A; Ziaco, E; Pacala, S

    2015-07-31

    The impacts of climate extremes on terrestrial ecosystems are poorly understood but important for predicting carbon cycle feedbacks to climate change. Coupled climate-carbon cycle models typically assume that vegetation recovery from extreme drought is immediate and complete, which conflicts with the understanding of basic plant physiology. We examined the recovery of stem growth in trees after severe drought at 1338 forest sites across the globe, comprising 49,339 site-years, and compared the results with simulated recovery in climate-vegetation models. We found pervasive and substantial "legacy effects" of reduced growth and incomplete recovery for 1 to 4 years after severe drought. Legacy effects were most prevalent in dry ecosystems, among Pinaceae, and among species with low hydraulic safety margins. In contrast, limited or no legacy effects after drought were simulated by current climate-vegetation models. Our results highlight hysteresis in ecosystem-level carbon cycling and delayed recovery from climate extremes. Copyright © 2015, American Association for the Advancement of Science.

  7. Predicting the dynamics of a native Araucaria forest using a distance-independent individual tree-growth model

    OpenAIRE

    Enrique Orellana; Afonso Figueiredo Filho; Sylvio Péllico Netto; Jerome Klaas Vanclay

    2016-01-01

    Background: In recent decades, native Araucaria forests in Brazil have become fragmented due to the conversion of forest to agricultural lands and commercial tree plantations. Consequently, the forest dynamics in this forest type have been poorly investigated, as most fragments are poorly structured in terms of tree size and diversity. Methods: We developed a distance-independent individual tree-growth model to simulate the forest dynamics in a native Araucaria forest located pred...

  8. Forest Productivity and Diversity: Using Ecological Theory and Landscape Models to Guide Sustainable Forest Management

    Energy Technology Data Exchange (ETDEWEB)

    Huston, M.A.

    1998-11-01

    Sustainable forest management requires maintaining or increasing ecosystem productivity, while preserving or restoring natural levels of biodiversity. Application of general concepts from ecological theory, along with use of mechanistic, landscape-based computer models, can contribute to the successful achievement of both of these objectives. Ecological theories based on the energetics and dynamics of populations can be used to predict the general distribution of individual species, the diversity of different types of species, ecosystem process rates and pool sizes, and patterns of spatial and temporal heterogeneity over a broad range of environmental conditions. This approach requires subdivision of total biodiversity into functional types of organisms, primarily because different types of organisms respond very differently to the spatial and temporal variation of environmental conditions on landscapes. The diversity of species of the same functional type (particularly among plants) tends to be highest at relatively low levels of net primary productivity, while the total number of different functional types (particularly among animals) tends to be highest at high levels of productivity (e.g., site index or potential net primary productivity). In general, the diversity of animals at higher trophic levels (e.g., predators) reaches its maximum at much higher levels of productivity than the diversity of lower trophic levels (e.g., plants). This means that a single environment cannot support high diversity of all types of organisms. Within the framework of the general patterns described above, the distributions, population dynamics, and diversity of organisms in specific regions can be predicted more precisely using a combination of computer simulation models and GIS data based on satellite information and ground surveys. Biophysical models that use information on soil properties, climate, and hydrology have been developed to predict how the abundance and spatial

  9. A molecular investigation of soil organic carbon composition across a subalpine catchment

    Science.gov (United States)

    Hsu, Hsiao-Tieh; Lawrence, Corey R.; Winnick, Matthew J.; Bargar, John R.; Maher, Katharine

    2018-01-01

    The dynamics of soil organic carbon (SOC) storage and turnover are a critical component of the global carbon cycle. Mechanistic models seeking to represent these complex dynamics require detailed SOC compositions, which are currently difficult to characterize quantitatively. Here, we address this challenge by using a novel approach that combines Fourier transform infrared spectroscopy (FT-IR) and bulk carbon X-ray absorption spectroscopy (XAS) to determine the abundance of SOC functional groups, using elemental analysis (EA) to constrain the total amount of SOC. We used this SOC functional group abundance (SOC-fga) method to compare variability in SOC compositions as a function of depth across a subalpine watershed (East River, Colorado, USA) and found a large degree of variability in SOC functional group abundances between sites at different elevations. Soils at a lower elevation are predominantly composed of polysaccharides, while soils at a higher elevation have more substantial portions of carbonyl, phenolic, or aromatic carbon. We discuss the potential drivers of differences in SOC composition between these sites, including vegetation inputs, internal processing and losses, and elevation-driven environmental factors. Although numerical models would facilitate the understanding and evaluation of the observed SOC distributions, quantitative and meaningful measurements of SOC molecular compositions are required to guide such models. Comparison among commonly used characterization techniques on shared reference materials is a critical next step for advancing our understanding of the complex processes controlling SOC compositions.

  10. Simulating the Effects of Fire on Forests in the Russian Far East: Integrating a Fire Danger Model and the FAREAST Forest Growth Model Across a Complex Landscape

    Science.gov (United States)

    Sherman, N. J.; Loboda, T.; Sun, G.; Shugart, H. H.; Csiszar, I.

    2008-12-01

    The remaining natural habitat of the critically endangered Amur tiger (Panthera tigris altaica) and Amur leopard (Panthera pardus orientalis) is a vast, biologically and topographically diverse area in the Russian Far East (RFE). Although wildland fire is a natural component of ecosystem functioning in the RFE, severe or repeated fires frequently re-set the process of forest succession, which may take centuries to return the affected forests to the pre-fire state and thus significantly alters habitat quality and long-term availability. The frequency of severe fire events has increased over the last 25 years, leading to irreversible modifications of some parts of the species' habitats. Moreover, fire regimes are expected to continue to change toward more frequent and severe events under the influence of climate change. Here we present an approach to developing capabilities for a comprehensive assessment of potential Amur tiger and leopard habitat availability throughout the 21st century by integrating regionally parameterized fire danger and forest growth models. The FAREAST model is an individual, gap-based model that simulates forest growth in a single location and demonstrates temporally explicit forest succession leading to mature forests. Including spatially explicit information on probabilities of fire occurrence at 1 km resolution developed from the regionally specific remotely -sensed data-driven fire danger model improves our ability to provide realistic long-term projections of potential forest composition in the RFE. This work presents the first attempt to merge the FAREAST model with a fire disturbance model, to validate its outputs across a large region, and to compare it to remotely-sensed data products as well as in situ assessments of forest structure. We ran the FAREAST model at 1,000 randomly selected points within forested areas in the RFE. At each point, the model was calibrated for temperature, precipitation, slope, elevation, and fire

  11. Modelling associations between public understanding, engagement and forest conditions in the Inland Northwest, USA.

    Directory of Open Access Journals (Sweden)

    Joel Hartter

    Full Text Available Opinions about public lands and the actions of private non-industrial forest owners in the western United States play important roles in forested landscape management as both public and private forests face increasing risks from large wildfires, pests and disease. This work presents the responses from two surveys, a random-sample telephone survey of more than 1500 residents and a mail survey targeting owners of parcels with 10 or more acres of forest. These surveys were conducted in three counties (Wallowa, Union, and Baker in northeast Oregon, USA. We analyze these survey data using structural equation models in order to assess how individual characteristics and understanding of forest management issues affect perceptions about forest conditions and risks associated with declining forest health on public lands. We test whether forest understanding is informed by background, beliefs, and experiences, and whether as an intervening variable it is associated with views about forest conditions on publicly managed forests. Individual background characteristics such as age, gender and county of residence have significant direct or indirect effects on our measurement of understanding. Controlling for background factors, we found that forest owners with higher self-assessed understanding, and more education about forest management, tend to hold more pessimistic views about forest conditions. Based on our results we argue that self-assessed understanding, interest in learning, and willingness to engage in extension activities together have leverage to affect perceptions about the risks posed by declining forest conditions on public lands, influence land owner actions, and affect support for public policies. These results also have broader implications for management of forested landscapes on public and private lands amidst changing demographics in rural communities across the Inland Northwest where migration may significantly alter the composition of

  12. Using urban forest assessment tools to model bird habitat potential

    Science.gov (United States)

    Susannah B. Lerman; Keith H. Nislow; David J. Nowak; Stephen DeStefano; David I. King; D. Todd. Jones-Farrand

    2014-01-01

    The alteration of forest cover and the replacement of native vegetation with buildings, roads, exotic vegetation, and other urban features pose one of the greatest threats to global biodiversity. As more land becomes slated for urban development, identifying effective urban forest wildlife management tools becomes paramount to ensure the urban forest provides habitat...

  13. Modeling Forest Resilience in Hindu Kush Himalaya using Geo ...

    Indian Academy of Sciences (India)

    48

    The theory of alternative stable states in a forest ecosystem suggests that the regime shift. 5 among various forest .... the TCC% data to define various forest formations, and estimated their resilience by accounting. 1 to precipitation. 2. 3 ..... Acknowledgements: The financial support for carrying out the work (Contract No. 29.

  14. Modeled forest inventory data suggest climate benefits from fuels management

    Science.gov (United States)

    Jeremy S. Fried; Theresa B. Jain; Jonathan. Sandquist

    2013-01-01

    As part of a recent synthesis addressing fuel management in dry, mixed-conifer forests we analyzed more than 5,000 Forest Inventory and Analysis (FIA) plots, a probability sample that represents 33 million acres of these forests throughout Washington, Oregon, Idaho, Montana, Utah, and extreme northern California. We relied on the BioSum analysis framework that...

  15. Calcium induces long-term legacy effects in a subalpine ecosystem.

    Directory of Open Access Journals (Sweden)

    Urs Schaffner

    Full Text Available Human activities have transformed a significant proportion of the world's land surface, with profound effects on ecosystem processes. Soil applications of macronutrients such as nitrate, phosphorus, potassium or calcium are routinely used in the management of croplands, grasslands and forests to improve plant health or increase productivity. However, while the effects of continuous fertilization and liming on terrestrial ecosystems are well documented, remarkably little is known about the legacy effect of historical fertilization and liming events in terrestrial ecosystems and of the mechanisms involved. Here, we show that more than 70 years after the last application of lime on a subalpine grassland, all major soil and plant calcium pools were still significantly larger in limed than in unlimed plots, and that the resulting shift in the soil calcium/aluminium ratio continues to affect ecosystem services such as primary production. The difference in the calcium content of the vegetation and the topmost 10 cm of the soil in limed vs. unlimed plots amounts to approximately 19.5 g m(-2, equivalent to 16.3% of the amount that was added to the plots some 70 years ago. In contrast, plots that were treated with nitrogen-phosphorus-potassium fertilizer in the 1930s did not differ from unfertilized plots in any of the soil and vegetation characteristics measured. Our findings suggest that the long-term legacy effect of historical liming is due to long-term storage of added calcium in stable soil pools, rather than a general increase in nutrient availability. Our results demonstrate that single applications of calcium in its carbonated form can profoundly and persistently alter ecosystem processes and services in mountain ecosystems.

  16. Hydrologic flow path development varies by aspect during spring snowmelt in complex subalpine terrain

    Science.gov (United States)

    Webb, Ryan W.; Fassnacht, Steven R.; Gooseff, Michael N.

    2018-01-01

    In many mountainous regions around the world, snow and soil moisture are key components of the hydrologic cycle. Preferential flow paths of snowmelt water through snow have been known to occur for years with few studies observing the effect on soil moisture. In this study, statistical analysis of the topographical and hydrological controls on the spatiotemporal variability of snow water equivalent (SWE) and soil moisture during snowmelt was undertaken at a subalpine forested setting with north, south, and flat aspects as a seasonally persistent snowpack melts. We investigated if evidence of preferential flow paths in snow can be observed and the effect on soil moisture through measurements of snow water equivalent and near-surface soil moisture, observing how SWE and near-surface soil moisture vary on hillslopes relative to the toes of hillslopes and flat areas. We then compared snowmelt infiltration beyond the near-surface soil between flat and sloping terrain during the entire snowmelt season using soil moisture sensor profiles. This study was conducted during varying snowmelt seasons representing above-normal, relatively normal, and below-normal snow seasons in northern Colorado. Evidence is presented of preferential meltwater flow paths at the snow-soil interface on the north-facing slope causing increases in SWE downslope and less infiltration into the soil at 20 cm depth; less association is observed in the near-surface soil moisture (top 7 cm). We present a conceptualization of the meltwater flow paths that develop based on slope aspect and soil properties. The resulting flow paths are shown to divert at least 4 % of snowmelt laterally, accumulating along the length of the slope, to increase the snow water equivalent by as much as 170 % at the base of a north-facing hillslope. Results from this study show that snow acts as an extension of the vadose zone during spring snowmelt and future hydrologic investigations will benefit from studying the snow and soil

  17. A Forest Structure Dynamics Model for Driving Three-Dimensional Canopy Radiative Transfer Simulations

    Science.gov (United States)

    Yang, W.; Kobayashi, H.; Kondoh, A.

    2016-12-01

    Three-dimensional (3-D) Monte Carlo (MC)-based radiative transfer (RT) models can simulate highly detailed forest environments, and have produced simulations that agree well with observations; thus, they are routinely used for benchmarking in intercomparisons of RT models. However, MC-based RT models have not been widely applied to the development of inversion algorithms for generating global remote sensing products of forests, due mainly to the difficulties in obtaining realistic forest structures for a variety of forest biomes. In this study, we developed a Forest Structure Dynamics Model (FSDM) to facilitate the application of MC-based RT models to global forests. In this model, the tree architectures are determined based on allometric equations, and the tree locations within a study domain are determined by statistical distributions. The performance of the FSDM was evaluated using field measurements of forest landscapes at two sites located at Järvselja, Estonia and the Poker Flat Research Range (PFRR), USA, respectively. The bidirectional reflectance factor (BRF) for the two study sites was simulated by an MC-based RT model, based on the measured forest stands and modeled stands from the FSDM. A comparison of the results demonstrated that the simulated BRF based on the measured forest stands agreed well with the simulated BRF based on the modeled stands from the FSDM for the two study sites. The applicability of the FSDM to a leaf area index (LAI) retrieval algorithm was also verified using simulations from the MC-based RT model. The results indicate that the FSDM can provide reasonable forest structures to drive 3-D canopy RT models, with no loss of simulation accuracy. When combined with several existing field data sets and satellite products, the FSDM can be used to generate a typical stand structure database for global forest biomes.

  18. PnET Models: Carbon, Nitrogen, Water Dynamics in Forest Ecosystems (Vers. 4 and 5)

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: PnET (Photosynthetic / EvapoTranspiration model) is a nested series of models of carbon, water, and nitrogen dynamics in forest ecosystems. The models can...

  19. PnET Models: Carbon, Nitrogen, Water Dynamics in Forest Ecosystems (Vers. 4 and 5)

    Data.gov (United States)

    National Aeronautics and Space Administration — PnET (Photosynthetic / EvapoTranspiration model) is a nested series of models of carbon, water, and nitrogen dynamics in forest ecosystems. The models can be used to...

  20. Hierarchical, parallel computing strategies using component object model for process modelling responses of forest plantations to interacting multiple stresses

    Science.gov (United States)

    J. G. Isebrands; G. E. Host; K. Lenz; G. Wu; H. W. Stech

    2000-01-01

    Process models are powerful research tools for assessing the effects of multiple environmental stresses on forest plantations. These models are driven by interacting environmental variables and often include genetic factors necessary for assessing forest plantation growth over a range of different site, climate, and silvicultural conditions. However, process models are...

  1. Potential of forest management to reduce French carbon emissions - regional modelling of the French forest carbon balance from the forest to the wood.

    Science.gov (United States)

    Valade, A.; Luyssaert, S.; Bellassen, V.; Vallet, P.

    2015-12-01

    In France the low levels of forest harvest (40 Mm3 per year over a volume increment of 89Mm3) is frequently cited to push for a more intensive management of the forest that would help reducing CO2 emissions. This reasoning overlooks the medium-to-long-term effects on the carbon uptake at the national scale that result from changes in the forest's structure and delayed emissions from products decay and bioenergy burning, both determinant for the overall C fluxes between the biosphere and the atmosphere. To address the impacts of an increase in harvest removal on biosphere-atmosphere carbon fluxes at national scale, we build a consistent regional modeling framework to integrate the forest-carbon system from photosynthesis to wood uses. We aim at bridging the gap between regional ecosystem modeling and land managers' considerations, to assess the synergistic and antagonistic effects of management strategies over C-based forest services: C-sequestration, energy and material provision, fossil fuel substitution. For this, we built on inventory data to develop a spatial forest growth simulator and design a novel method for diagnosing the current level of management based on stand characteristics (density, quadratic mean diameter or exploitability). The growth and harvest simulated are then processed with a life cycle analysis to account for wood transformation and uses. Three scenarii describe increases in biomass removals either driven by energy production target (set based on national prospective with a lock on minimum harvest diameters) or by changes in management practices (shorter or longer rotations, management of currently unmanaged forests) to be compared with business as usual simulations. Our management levels' diagnostics quantifies undermanagement at national scale and evidences the large weight of ownership-based undermanagement with an average of 26% of the national forest (between 10% and 40% per species) and thus represents a huge potential wood resource

  2. Limnological research in the deep southern subalpine lakes: synthesis, directions and perspectives

    Directory of Open Access Journals (Sweden)

    Nico Salmaso

    2010-06-01

    Full Text Available Based on a selection of 230 papers published during the last 15 years in international journals, the present work aims at evaluating the state of the art of limnological research in the deep southern subalpine lakes (DSL: Garda, Iseo, Como, Lugano and Maggiore. Historically, most of the limnological research was fostered by the need to find solutions to the problems connected with eutrophication and pollution. Many data are available on the thermal structure, algal nutrient concentrations and phytoplankton of the DSL, while other topics still remain more or less constrained to single lakes. Apart from this geographical bias, a number of aspects emerged from this synoptic view. Limnological research is still linked to the concept of scientific monitoring, while experimental studies and modelling are confined to specific niches; the integration of different disciplines is held back by the division of studies on different compartments; integration of studies and synoptic analyses at a macro regional scale have been carried out only for specific research areas. The DSL are increasingly threatened by new pressures (climatic change, excessive proliferation of toxic cyanobacteria, introduction of new species and new micropollutants and by the interactions among these new and old stressors. In this rapidly changing situation, the paper emphasises the need to define criteria to be used to distinguish research able to produce relevant results and predictive models, which are essential elements for an efficient management of water resources.

  3. Climate, geography, and tree establishment in subalpine meadows of the Olympic Mountains, Washington, USA

    Science.gov (United States)

    Woodward, Andrea; Schreiner, Edward G.; Silsbee, D.G.

    1995-01-01

    Noticeable changes in vegetation distribution have occurred in the Pacific Northwest during the last century as trees have established in some subalpine meadows. To study the relationship of this process to climate, recently established trees were aged in six subalpine meadows in the Olympic Mountains, Washington. The sites represent three points along a steep precipitation gradient. Subalpine fir (Abies lasiocarpa) has been establishing at the dry end of the gradient, mountain hemlock (Tsuga mertensiana) at the wet end, and both species in the center. Establishment patterns were compared with deviations from the century-long average for these weather variables: winter precipitation, Palmer Drought Severity Index, and winter, October, and May temperatures. Results show that establishment occurred in dry areas when weather conditions were wetter than average, and in wet areas under drier than average conditions. Establishment at central sites did not show consistent relationships with climate. If future climatic conditions continue to warm, establishment of subalpine fir in subalpine meadows in dry areas may cease and mountain hemlock may resume in wet areas.

  4. Modelling the carbon budget of intensive forest monitoring sites in Germany using the simulation model BIOME-BGC

    OpenAIRE

    Jochheim, H.; Puhlmann, M.; Beese, F.; Berthold, D.; Einert, P.; Kallweit, R.; Konopatzky, A.; Meesenburg, H.; Meiwes, K.-J.; Raspe, S.; Schulte-Bisping, H.; Schulz, C.

    2008-01-01

    It is shown that by calibrating the simulation model BIOME-BGC with mandatory and optional Level II data, within the ICP Forest programme, a well-founded calculation of the carbon budget of forest stands is achievable and, based on succeeded calibration, the modified BIOME-BGC model is a useful tool to assess the effect of climate change on forest ecosystems. peerReviewed

  5. Linking state-and-transition simulation and timber supply models for forest biomass production scenarios

    Science.gov (United States)

    Costanza, Jennifer; Abt, Robert C.; McKerrow, Alexa; Collazo, Jaime

    2015-01-01

    We linked state-and-transition simulation models (STSMs) with an economics-based timber supply model to examine landscape dynamics in North Carolina through 2050 for three scenarios of forest biomass production. Forest biomass could be an important source of renewable energy in the future, but there is currently much uncertainty about how biomass production would impact landscapes. In the southeastern US, if forests become important sources of biomass for bioenergy, we expect increased land-use change and forest management. STSMs are ideal for simulating these landscape changes, but the amounts of change will depend on drivers such as timber prices and demand for forest land, which are best captured with forest economic models. We first developed state-and-transition model pathways in the ST-Sim software platform for 49 vegetation and land-use types that incorporated each expected type of landscape change. Next, for the three biomass production scenarios, the SubRegional Timber Supply Model (SRTS) was used to determine the annual areas of thinning and harvest in five broad forest types, as well as annual areas converted among those forest types, agricultural, and urban lands. The SRTS output was used to define area targets for STSMs in ST-Sim under two scenarios of biomass production and one baseline, business-as-usual scenario. We show that ST-Sim output matched SRTS targets in most cases. Landscape dynamics results indicate that, compared with the baseline scenario, forest biomass production leads to more forest and, specifically, more intensively managed forest on the landscape by 2050. Thus, the STSMs, informed by forest economics models, provide important information about potential landscape effects of bioenergy production.

  6. Microplastic pollution in the surface waters of Italian Subalpine Lakes.

    Science.gov (United States)

    Sighicelli, Maria; Pietrelli, Loris; Lecce, Francesca; Iannilli, Valentina; Falconieri, Mauro; Coscia, Lucia; Di Vito, Stefania; Nuglio, Simone; Zampetti, Giorgio

    2018-05-01

    Plastic debris incidence in marine environment was already highlighted in the early 1970s. Over the last decade, microplastic pollution in the environment has received increasing attention and is now an emerging research area. Many studies have focused on quantifying microplastic abundance in the marine environment, while there are relatively few data on microplastic occurrence in freshwater environment. Recent studies have reported high concentrations of microplastics in lakes and rivers, although the understanding of several factors influencing source, transport and fate is still limited. This study compares different lakes and the common factors, which could influence the occurrence and distribution of microplastics. The three subalpine lakes monitored include Lake Maggiore, Iseo and Garda. The selected sampling transects reflect the hydrologic conditions, the morphometric characteristics of these lakes, and other factors influencing the release of plastics debris in lakes. Particles of microplastics (<5 mm) were found in all sampled surfaces. The particles collected were classified depending on their number, shape and composition. The shape distribution showed the dominating occurrence of fragments (73.7%). The chemical composition of all examined samples clearly shows dominating presence of polyethylene (45%), polystyrene (18%) and polypropylene (15%). The results provide significant relations among the different contribution of direct and diffuse sources to the quantity of microplastics, highlighting the importance of understanding the spatial distribution dynamics of microplastics within a lake system that acts as a sink and source of plastic particles. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Modelling and economic evaluation of forest biome shifts under climate change in Southwest Germany

    Science.gov (United States)

    Marc Hanewinkel; Susan Hummel; Dominik. Cullmann

    2010-01-01

    We evaluated the economic effects of a predicted shift from Norway spruce (Picea abies) to European beech (Fagus sylvatica) for a forest area of 1.3 million ha in southwest Germany. The shift was modelled with a generalized linear model (GLM) by using presence/absence data from the National Forest Inventory in Baden-Wurttemberg...

  8. Equilibrium and non-equilibrium concepts in forest genetic modelling: population- and individually-based approaches

    NARCIS (Netherlands)

    Kramer, K.; Werf, van der D.C.

    2010-01-01

    The environment is changing and so are forests, in their functioning, in species composition, and in the species’ genetic composition. Many empirical and process-based models exist to support forest management. However, most of these models do not consider the impact of environmental changes and

  9. Declining forest productivity in aging forest stands: a modeling analysis of alternative hypotheses.

    Science.gov (United States)

    Murty, Danuse; McMurtrie, Ross E.; Ryan, Michael G.

    1996-01-01

    Several explanations have been advanced to account for the decline in forest net primary productivity (NPP) with age in closed-canopy stands including the hypotheses that: (1) sapwood maintenance respiration rate increases, reducing the availability of carbon to support new growth; (2) stomatal conductance and hence photosynthetic efficiency decline; and (3) soil nutrient availability declines. To evaluate these hypotheses we applied the ecosystem model G'DAY to a 40- and a 245-year-old stand of lodgepole pine (Pinus contorta Dougl. ex Loud.), growing on infertile soils. Net primary productivity estimated from biomass data was 0.47 and 0.25 kg C m(-2) year(-1) and foliar nitrogen/carbon ratio (N/C) was 0.0175 and 0.017 for the 40- and 245-year-old stands, respectively. Productivities of the young and old stands were derived from a graphical analysis of the G'DAY model. The graphical analysis also indicated that the observed age-related decline in NPP can be explained in terms of interacting processes associated with Hypotheses 2 and 3. However, the relative importance of these two hypotheses differed depending on key model assumptions, in particular those relating to variation in soil N/C ratio. Thus, if we assumed that soil N/C ratio can vary significantly during stand development, then Hypotheses 2 and 3 jointly explain the decline in NPP, whereas if we assumed that soil N/C ratios are constant, then Hypothesis 3 alone explains the decline in NPP. The analysis revealed that only a small fraction of the decline of NPP can be explained in terms of increasing sapwood respiration.

  10. Alternative projections of the impacts of private investment on southern forests: a comparison of two large-scale forest sector models of the United States.

    Science.gov (United States)

    Ralph Alig; Darius Adams; John Mills; Richard Haynes; Peter Ince; Robert. Moulton

    2001-01-01

    The TAMM/NAPAP/ATLAS/AREACHANGE(TNAA) system and the Forest and Agriculture Sector Optimization Model (FASOM) are two large-scale forestry sector modeling systems that have been employed to analyze the U.S. forest resource situation. The TNAA system of static, spatial equilibrium models has been applied to make SO-year projections of the U.S. forest sector for more...

  11. Evapotranspiration and heat fluxes over a patchy forest - studied using modelling and measurements

    DEFF Research Database (Denmark)

    Sogachev, Andrey; Dellwik, Ebba; Boegh, Eva

    and latent heat flux above forest downwind of a forest edge show these fluxes to be larger than the available energy over the forest (Klaassen et al. 2002, Theor. Appl. Climatol. 72, 231-243). Because such flux measurements are very often used for calibration of forest parameters or model constants, further...... using these parameters without a proper interpretation in mesoscale or global circulation models can results in serious bias of estimates of modelled evapotranspiration or heat fluxes from given area. Since representative measurements focused on heterogeneous effects are scarce numerical modelling can...... be used to interpret the measurements. Recently, the atmospheric boundary layer (ABL) model SCADIS (Sogachev et al., 2002, Tellus 54B, 784-819) has been successfully applied to analyze the mechanisms of CO2 flux formation near a forest edge for neutrally stratified conditions (Sogachev et al., 2008...

  12. Spatial Simulation Modelling of Future Forest Cover Change Scenarios in Luangprabang Province, Lao PDR

    Directory of Open Access Journals (Sweden)

    Khamma Homsysavath

    2011-08-01

    Full Text Available Taking Luangprabang province in Lao Peoples’s Democratic Republic (PDR as an example, we simulated future forest cover changes under the business-as-usual (BAU, pessimistic and optimistic scenarios based on the Markov-cellular automata (MCA model. We computed transition probabilities from satellite-derived forest cover maps (1993 and 2000 using the Markov chains, while the “weights of evidence” technique was used to generate transition potential maps. The initial forest cover map (1993, the transition potential maps and the 1993–2000 transition probabilities were used to calibrate the model. Forest cover simulations were then performed from 1993 to 2007 at an annual time-step. The simulated forest cover map for 2007 was compared to the observed (actual forest cover map for 2007 in order to test the accuracy of the model. Following the successful calibration and validation, future forest cover changes were simulated up to 2014 under different scenarios. The MCA simulations under the BAU and pessimistic scenarios projected that current forest areas would decrease, whereas unstocked forest areas would increase in the future. Conversely, the optimistic scenario projected that current forest areas would increase in the future if strict forestry laws enforcing conservation in protected forest areas are implemented. The three simulation scenarios provide a very good case study for simulating future forest cover changes at the subnational level (Luangprabang province. Thus, the future simulated forest cover changes can possibly be used as a guideline to set reference scenarios as well as undertake REDD/REDD+ preparedness activities within the study area.

  13. Predictive modelling of the spatial pattern of past and future forest cover changes in India

    Science.gov (United States)

    Reddy, C. Sudhakar; Singh, Sonali; Dadhwal, V. K.; Jha, C. S.; Rao, N. Rama; Diwakar, P. G.

    2017-02-01

    This study was carried out to simulate the forest cover changes in India using Land Change Modeler. Classified multi-temporal long-term forest cover data was used to generate the forest covers of 1880 and 2025. The spatial data were overlaid with variables such as the proximity to roads, settlements, water bodies, elevation and slope to determine the relationship between forest cover change and explanatory variables. The predicted forest cover in 1880 indicates an area of 10,42,008 km2, which represents 31.7% of the geographical area of India. About 40% of the forest cover in India was lost during the time interval of 1880-2013. Ownership of majority of forest lands by non-governmental agencies and large scale shifting cultivation are responsible for higher deforestation rates in the Northeastern states. The six states of the Northeast (Assam, Manipur, Meghalaya, Mizoram, Nagaland, Tripura) and one union territory (Andaman & Nicobar Islands) had shown an annual gross rate of deforestation of >0.3 from 2005 to 2013 and has been considered in the present study for the prediction of future forest cover in 2025. The modelling results predicted widespread deforestation in Northeast India and in Andaman & Nicobar Islands and hence is likely to affect the remaining forests significantly before 2025. The multi-layer perceptron neural network has predicted the forest cover for the period of 1880 and 2025 with a Kappa statistic of >0.70. The model predicted a further decrease of 2305 km2 of forest area in the Northeast and Andaman & Nicobar Islands by 2025. The majority of the protected areas are successful in the protection of the forest cover in the Northeast due to management practices, with the exception of Manas, Sonai-Rupai, Nameri and Marat Longri. The predicted forest cover scenario for the year 2025 would provide useful inputs for effective resource management and help in biodiversity conservation and for mitigating climate change.

  14. Determination of the Support Level of Local Organizations in a Model Forest Initiative: Do Local Stakeholders Have Willingness to Be Involved in the Model Forest Development?

    Directory of Open Access Journals (Sweden)

    Ahmet Tolunay

    2014-10-01

    Full Text Available Voluntary cooperation and the support of stakeholders carry a major importance in the development of Model Forests. The identification of the support level of local organizations as stakeholders in the Bucak Model Forest initiative, located in the Mediterranean region of Turkey, constitutes the theme of this study. Within this scope, the views of the stakeholders comprising local government units (LGUs, non-governmental organizations (NGOs, village councils (VCs, professional organizations (POs and forest products enterprises (FPEs located in the district of Bucak were collected by utilizing a survey technique. The data were analysed by using non-parametric statistical analyses due to the absence of a normal distribution. The results show that the information provided about the Model Forest concept to the stakeholders located in the district on the Bucak Model Forest initiative was identified as a factor impacting the support level. Moreover, it was also observed that the stakeholders were more willing to provide advisory support rather than financial support. NGOs and VCs were identified as stakeholders who could not provide financial support due to their restricted budgets. We discuss the benefits for a Model Forest initiative of establishing international cooperation to strengthen the local and regional sustainable development process.

  15. Evaluating the sensitivity of Eurasian forest biomass to climate change using a dynamic vegetation model

    International Nuclear Information System (INIS)

    Shuman, J K; Shugart, H H

    2009-01-01

    Climate warming could strongly influence the structure and composition of the Eurasian boreal forest. Temperature related changes have occurred, including shifts in treelines and changes in regeneration. Dynamic vegetation models are well suited to the further exploration of the impacts that climate change may have on boreal forests. Using the individual-based gap model FAREAST, forest composition and biomass are simulated at over 2000 sites across Eurasia. Biomass output is compared to detailed forest data from a representative sample of Russian forests and a sensitivity analysis is performed to evaluate the impact that elevated temperatures and modified precipitation will have on forest biomass and composition in Eurasia. Correlations between model and forest inventory biomass are strong for several boreal tree species. A significant relationship is shown between altered precipitation and biomass. This analysis showed that a modest increase in temperature of 2 deg. C across 200 years had no significant effect on biomass; however further exploration with increased warming reflective of values measured within Siberia, or at an increased rate, are warranted. Overall, FAREAST accurately simulates forest biomass and composition at sites throughout a large geographic area with widely varying climatic conditions and produces reasonable biomass responses to simulated climatic shifts. These results indicate that this model is robust and useful in making predictions regarding the effect of future climate change on boreal forest structure across Eurasia.

  16. Modeling forest defoliation using simulated BRDF and assessing its effect on reflectance and sensor reaching radiance

    Science.gov (United States)

    Rengarajan, Rajagopalan; Schott, John R.

    2016-09-01

    Remote sensing techniques such as change detection are widely used for mapping and monitoring forest cover to detect the declining health and vigor of forests. These techniques rely on the assumption that the biophysical variation in the forest introduces a corresponding variation in its reflectance. The biophysical variations are assessed by foresters, but these assessment techniques are expensive and cannot be performed frequently to identify a specific level of change in the forest, for example, infection due to gypsy moths that results in forest defoliation. Further, the interaction of atmosphere, sensor characteristics, and phenology that are inherent in the remotely sensed images makes it difficult to separate biophysical changes from observational effects. We have addressed these limitations by developing a method to model the spectral reflectance properties of forests with varying degrees of defoliation using the Digital Image and Remote Sensing Image Generation (DIRSIG) tool. This paper discusses the in-canopy radiative approach and the impact of defoliation on the reflectance and radiance observed by sensors such as Landsat. The results indicate that the relative variation in forest reflectance between a non-defoliated and a 30% defoliated deciduous forest can be as high as 10% in the NIR spectral band. A function can be fit to predict the level of defoliation from the relative variation in radiance. The modeling and analysis techniques can be extended to assess the impact of atmospheric factors and sensor characteristics relative to the biophysical changes as well as for assessing other biophysical variables in forests.

  17. Development of lichen response indexes using a regional gradient modeling approach for large-scale monitoring of forests

    Science.gov (United States)

    Susan Will-Wolf; Peter Neitlich

    2010-01-01

    Development of a regional lichen gradient model from community data is a powerful tool to derive lichen indexes of response to environmental factors for large-scale and long-term monitoring of forest ecosystems. The Forest Inventory and Analysis (FIA) Program of the U.S. Department of Agriculture Forest Service includes lichens in its national inventory of forests of...

  18. Modeling climate and fuel reduction impacts on mixed-conifer forest carbon stocks in the Sierra Nevada, California

    Science.gov (United States)

    Matthew D. Hurteau; Timothy A. Robards; Donald Stevens; David Saah; Malcolm North; George W. Koch

    2014-01-01

    Quantifying the impacts of changing climatic conditions on forest growth is integral to estimating future forest carbon balance. We used a growth-and-yield model, modified for climate sensitivity, to quantify the effects of altered climate on mixed-conifer forest growth in the Lake Tahoe Basin, California. Estimates of forest growth and live tree carbon stocks were...

  19. Sensitivity of subalpine tree seedlings and alpine plants to natural and manipulated climate variation: Initial results from an Alpine Treeline Warming Experiment (Invited)

    Science.gov (United States)

    Kueppers, L. M.

    2010-12-01

    Niche models and paleoecological studies indicate that future climate change will alter the geographic distributions of plant species. Changes in temperature, snowmelt timing, or moisture conditions at one edge of a species’ range may have different consequences for recruitment, carbon exchange, phenology, and survival than changes at another edge. Similarly, local genetic adaptation may constrain species and community responses to climate change. We have established a new experiment to investigate potential shifts in the distribution of subalpine tree species, and the alpine species they might replace. We are asking how tree species recruitment and alpine species growth and reproduction vary within their current ranges, and in response to temperature and soil moisture manipulations. We are also examining whether genetic provenance and ecosystem processes constrain tree seedling and alpine herb responses. Our Alpine Treeline Warming Experiment is located across three sites at Niwot Ridge, CO, ranging from near the lower limit of subalpine forest to alpine tundra. We use infrared heaters to raise growing season surface soil temperatures by 4-5°C, and to lengthen the growing season. The warming treatment is crossed with a soil moisture manipulation to distinguish effects due to higher temperatures from those due to drier soil. Each plot is a common garden sown with high and low elevation provenances of limber pine (Pinus flexilis) and Engelmann spruce (Picea engelmannii). We established an additional set of experimental plots to examine treatment effects on alpine species phenology, growth and reproduction. Under ambient conditions in 2009, tree seedling germination rate, lifespan, and first season survival was higher within the species’ current range than in the alpine, and for Engelmann spruce, was higher at the low elevation limit than the high elevation limit. Source population (low vs. high elevation) was a significant factor explaining natural variation in

  20. Assessing the accuracy and stability of variable selection methods for random forest modeling in ecology

    Science.gov (United States)

    Random forest (RF) modeling has emerged as an important statistical learning method in ecology due to its exceptional predictive performance. However, for large and complex ecological datasets there is limited guidance on variable selection methods for RF modeling. Typically, e...

  1. A climate sensitive model of carbon transfer through atmosphere, vegetation and soil in managed forest ecosystems

    Science.gov (United States)

    Loustau, D.; Moreaux, V.; Bosc, A.; Trichet, P.; Kumari, J.; Rabemanantsoa, T.; Balesdent, J.; Jolivet, C.; Medlyn, B. E.; Cavaignac, S.; Nguyen-The, N.

    2012-12-01

    For predicting the future of the forest carbon cycle in forest ecosystems, it is necessary to account for both the climate and management impacts. Climate effects are significant not only at a short time scale but also at the temporal horizon of a forest life cycle e.g. through shift in atmospheric CO2 concentration, temperature and precipitation regimes induced by the enhanced greenhouse effect. Intensification of forest management concerns an increasing fraction of temperate and tropical forests and untouched forests represents only one third of the present forest area. Predicting tools are therefore needed to project climate and management impacts over the forest life cycle and understand the consequence of management on the forest ecosystem carbon cycle. This communication summarizes the structure, main components and properties of a carbon transfer model that describes the processes controlling the carbon cycle of managed forest ecosystems. The model, GO+, links three main components, (i) a module describing the vegetation-atmosphere mass and energy exchanges in 3D, (ii) a plant growth module and a (iii) soil carbon dynamics module in a consistent carbon scheme of transfer from atmosphere back into the atmosphere. It was calibrated and evaluated using observed data collected on coniferous and broadleaved forest stands. The model predicts the soil, water and energy balance of entire rotations of managed stands from the plantation to the final cut and according to a range of management alternatives. It accounts for the main soil and vegetation management operations such as soil preparation, understorey removal, thinnings and clearcutting. Including the available knowledge on the climatic sensitivity of biophysical and biogeochemical processes involved in atmospheric exchanges and carbon cycle of forest ecosystems, GO+ can produce long-term backward or forward simulations of forest carbon and water cycles under a range of climate and management scenarios. This

  2. Keystone Species, Forest and Landscape: A Model to Select Protected Areas

    Science.gov (United States)

    Lins, Daniela Barbosa da Silva; Gardon, Fernando Ravanini; Meyer, João Frederico da Costa Azevedo; Santos, Rozely Ferreira dos

    2017-06-01

    The selection of forest fragments for conservation is usually based on spatial parameters as forest size and canopy integrity. This strategy assumes that chosen fragments present high conservation status, ensuring biodiversity and ecological functions. We argue that a well-preserved forest fragment that remains connected by the landscape structure, does not necessarily hold attributes that ensure the presence of keystone species. We also discuss that the presence of keystone species does not always mean that it has the best conditions for its occurrence and maintenance. We developed a model to select areas in forest landscapes to be prioritized for protection based on suitability curves that unify and compare spatial indicators of three categories: forest fragment quality, landscape quality, and environmental conditions for the occurrence of a keystone species. We use a case study to compare different suitability degrees for Euterpe edulis presence, considered an important functional element in Atlantic Forest (São Paulo, Brazil) landscapes and a forest resource for local people. The results show that the identification of medium or advanced stage fragments as singular indicator of forest quality does not guarantee the existence or maintenance of this keystone species. Even in some well-preserved forest fragments, connected to others and with palm presence, the reverse J-shaped distribution of the population size structure is not sustained and these forests continue to be threatened due to human disturbances.

  3. Keystone Species, Forest and Landscape: A Model to Select Protected Areas.

    Science.gov (United States)

    Lins, Daniela Barbosa da Silva; Gardon, Fernando Ravanini; Meyer, João Frederico da Costa Azevedo; Santos, Rozely Ferreira Dos

    2017-06-01

    The selection of forest fragments for conservation is usually based on spatial parameters as forest size and canopy integrity. This strategy assumes that chosen fragments present high conservation status, ensuring biodiversity and ecological functions. We argue that a well-preserved forest fragment that remains connected by the landscape structure, does not necessarily hold attributes that ensure the presence of keystone species. We also discuss that the presence of keystone species does not always mean that it has the best conditions for its occurrence and maintenance. We developed a model to select areas in forest landscapes to be prioritized for protection based on suitability curves that unify and compare spatial indicators of three categories: forest fragment quality, landscape quality, and environmental conditions for the occurrence of a keystone species. We use a case study to compare different suitability degrees for Euterpe edulis presence, considered an important functional element in Atlantic Forest (São Paulo, Brazil) landscapes and a forest resource for local people. The results show that the identification of medium or advanced stage fragments as singular indicator of forest quality does not guarantee the existence or maintenance of this keystone species. Even in some well-preserved forest fragments, connected to others and with palm presence, the reverse J-shaped distribution of the population size structure is not sustained and these forests continue to be threatened due to human disturbances.

  4. Evaluation of spatial models to predict vulnerability of forest birds to brood parasitism by cowbirds

    Science.gov (United States)

    Gustafson, E.J.; Knutson, M.G.; Niemi, G.J.; Friberg, M.

    2002-01-01

    We constructed alternative spatial models at two scales to predict Brown-headed Cowbird (Molothrus ater) parasitism rates from land cover maps. The local-scale models tested competing hypotheses about the relationship between cowbird parasitism and distance of host nests from a forest edge (forest-nonforest boundary). The landscape models tested competing hypotheses about how landscape features (e.g., forests, agricultural fields) interact to determine rates of cowbird parasitism. The models incorporate spatial neighborhoods with a radius of 2.5 km in their formulation, reflecting the scale of the majority of cowbird commuting activity. Field data on parasitism by cowbirds (parasitism rate and number of cowbird eggs per nest) were collected at 28 sites in the Driftless Area Ecoregion of Wisconsin, Minnesota, and Iowa and were compared to the predictions of the alternative models. At the local scale, there was a significant positive relationship between cowbird parasitism and mean distance of nest sites from the forest edge. At the landscape scale, the best fitting models were the forest-dependent and forest-fragmentation-dependent models, in which more heavily forested and less fragmented landscapes had higher parasitism rates. However, much of the explanatory power of these models results from the inclusion of the local-scale relationship in these models. We found lower rates of cowbird parasitism than did most Midwestern studies, and we identified landscape patterns of cowbird parasitism that are opposite to those reported in several other studies of Midwestern songbirds. We caution that cowbird parasitism patterns can be unpredictable, depending upon ecoregional location and the spatial extent, and that our models should be tested in other ecoregions before they are applied there. Our study confirms that cowbird biology has a strong spatial component, and that improved spatial models applied at multiple spatial scales will be required to predict the effects of

  5. Response of high-elevation forests in the Olympic Mountains to climatic change

    Science.gov (United States)

    Zolbrod, A.N.; Peterson, D.L.

    1999-01-01

    The gap model ZELIG was used to examine the effects of increased temperature (2°C) and altered precipitation on high-elevation ecosystems of the Olympic Mountains, Washington, U.S.A. Changes in tree species distribution and abundance, as well as stand biomass, were examined on north and south aspects in the dry northeast (NE) and wet southwest (SW) regions of the Olympics for (i) warmer, (ii) warmer and 20% wetter, and (iii) warmer and 20% drier climatic-change scenarios. Dominant tree species shift upwards 300-600 m in elevation in the SW, with subalpine meadows and Tsuga mertensiana (Bong.) Carr. forests being replaced by Abies amabilis (Dougl.) Forbes forests at higher elevations and A. amabilis forests being replaced by Tsuga heterophylla (Raf.) Sarg. forests at lower elevations. In the NE, drought-tolerant species become dominant approximately 200 m lower than present, with A. lasiocarpa dominating the north aspect and Pinus contorta Dougl. ex Loud. the south aspect. Biomass increases in the SW and generally decreases in the NE, depending on aspect and precipitation regime. This study suggests that species and site-specific responses at mesoscale (e.g., wet vs. dry climatic regime) and microscale (e.g., north vs. south aspect) resolutions must be characterized to quantify the variation in potential effects of climatic change on forest vegetation in mountainous regions.

  6. 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

  7. Modeling belowground biomass of black cohosh, a medicinal forest product.

    Science.gov (United States)

    James Chamberlain; Gabrielle Ness; Christine Small; Simon Bonner; Elizabeth Hiebert

    2014-01-01

    Tens of thousands of kilograms of rhizomes and roots of Actaea racemosa L., a native Appalachian forest perennial, are harvested every year and used for the treatment of menopausal conditions. Sustainable management of this and other wild-harvested non-timber forest products requires the ability to effectively and reliably inventory marketable plant...

  8. Evaluating Multiple Imputation Models for the Southern Annual Forest Inventory

    Science.gov (United States)

    Gregory A. Reams; Joseph M. McCollum

    1999-01-01

    The USDA Forest Service's Southern Research Station is implementing an annualized forest survey in thirteen states. The sample design is a systematic sample of five interpenetrating grids (panels), where each panel is measured sequentially. For example, panel one information is collected in year one, and panel five in year five. The area representative and time...

  9. Growth and yield model application in tropical rain forest management

    Science.gov (United States)

    James Atta-Boateng; John W., Jr. Moser

    2000-01-01

    Analytical tools are needed to evaluate the impact of management policies on the sustainable use of rain forest. Optimal decisions concerning the level of management inputs require accurate predictions of output at all relevant input levels. Using growth data from 40 l-hectare permanent plots obtained from the semi-deciduous forest of Ghana, a system of 77 differential...

  10. Forest ingrowth prediction model for the Northeastern United States

    Science.gov (United States)

    Linda S. Gribko

    1997-01-01

    In the last 20 years, there has been a revival of interest in the use of uneven-aged forest management techniques in the production of timber and forest amenity values. Uneven-aged management is coming into renewed favor especially among non-industrial private landowners in the northeastern United States. The practice allows periodic timber removals on relatively small...

  11. Modeling the cumulative watershed effects of forest management strategies

    Science.gov (United States)

    R. R. Ziemer; J. Lewis; R. M. Rice; T. E. Lisle

    1991-01-01

    Abstract - There is increasing concern over the possibility of adverse cumulative watershed effects from intensive forest management. It is impractical to address many aspects of the problem experimentally because to do so would require studying large watersheds for 100 yr or more. One such aspect is the long-term effect of forest management strategies on erosion and...

  12. Simulating ectomycorrhiza in boreal forests: implementing ectomycorrhizal fungi model MYCOFON in CoupModel (v5

    Directory of Open Access Journals (Sweden)

    H. He

    2018-02-01

    Full Text Available The symbiosis between plants and Ectomycorrhizal fungi (ECM is shown to considerably influence the carbon (C and nitrogen (N fluxes between the soil, rhizosphere, and plants in boreal forest ecosystems. However, ECM are either neglected or presented as an implicit, undynamic term in most ecosystem models, which can potentially reduce the predictive power of models.In order to investigate the necessity of an explicit consideration of ECM in ecosystem models, we implement the previously developed MYCOFON model into a detailed process-based, soil–plant–atmosphere model, Coup-MYCOFON, which explicitly describes the C and N fluxes between ECM and roots. This new Coup-MYCOFON model approach (ECM explicit is compared with two simpler model approaches: one containing ECM implicitly as a dynamic uptake of organic N considering the plant roots to represent the ECM (ECM implicit, and the other a static N approach in which plant growth is limited to a fixed N level (nonlim. Parameter uncertainties are quantified using Bayesian calibration in which the model outputs are constrained to current forest growth and soil C ∕ N ratio for four forest sites along a climate and N deposition gradient in Sweden and simulated over a 100-year period.The nonlim approach could not describe the soil C ∕ N ratio due to large overestimation of soil N sequestration but simulate the forest growth reasonably well. The ECM implicit and explicit approaches both describe the soil C ∕ N ratio well but slightly underestimate the forest growth. The implicit approach simulated lower litter production and soil respiration than the explicit approach. The ECM explicit Coup–MYCOFON model provides a more detailed description of internal ecosystem fluxes and feedbacks of C and N between plants, soil, and ECM. Our modeling highlights the need to incorporate ECM and organic N uptake into ecosystem models, and the nonlim approach is not recommended for future long

  13. Regeneration in gap models: priority issues for studying forest responses to climate change

    NARCIS (Netherlands)

    Price, D.T.; Zimmermann, N.E.; Meer, van der P.J.; Lexer, M.J.; Leadley, P.; Jorritsma, I.T.M.; Schaber, J.; Clark, D.F.; Lasch, P.; McNulty, S.; Wu, J.; Smith, B.

    2001-01-01

    Recruitment algorithms in forest gap models are examined with particular regard to their suitability for simulating forest ecosystem responses to a changing climate. The traditional formulation of recruitment is found limiting in three areas. First, the aggregation of different regeneration stages

  14. Evapotranspiration estimates from eddy covariance towers and hydrologic modeling in managed forests in Northern Wisconsin, USA

    Science.gov (United States)

    Ge Sun; A. Noormets; J. Chen; S.G. McNulty

    2008-01-01

    Direct measurement of ecosystem evapotranspiration by the eddy covariance method and simulation modeling were employed to quantify the growing season (May–October) evapotranspiration (ET) of eight forest ecosystems representing a management gradient in dominant forest types and age classes in the Upper Great Lakes Region from 2002 to 2003. We measured net exchange of...

  15. A model of wind-influenced leaf litterfall in a mixed hardwood forest

    NARCIS (Netherlands)

    Staelens, Jeroen; Nachtergale, Lieven; Luyssaert, Sebastiaan; Lust, Noël

    2003-01-01

    Litterfall is an important ecological process in forest ecosystem functioning. Some attempts have been made to develop spatially explicit models of litterfall, but wind influence has never been included. Therefore, we studied the effect of wind on litterfall in an intimately mixed birch-oak forest

  16. Strategic management of five deciduous forest invaders using Microstegium vimineum as a model species

    Science.gov (United States)

    Cynthia D. Huebner

    2007-01-01

    This paper links key plant invasive traits with key landscape traits to define strategic management for five common forest invaders, using empirical data of Microstegium vimineum dispersal into forests as a preliminary model. Microstegium vimineum exhibits an Allee effect that may allow management to focus on treating its source...

  17. Forest Conservation Opportunity Areas - Conservative Model (ECO_RES.COA_FORREST66)

    Science.gov (United States)

    This layer designates areas with potential for forest conservation. These are areas of natural or semi-natural forest land cover patches that area at least 395 meters away from roads and away from patch edges. OAs were modeled by creating distance grids using the National Land Cover Database and the Census Bureau's TIGER road files.

  18. Forest Conservation Opportunity Areas - Liberal Model (ECO_RES.COA_FORREST33)

    Science.gov (United States)

    This layer designates areas with potential for forest conservation. These are areas of natural or semi-natural forest land cover patches that are at least 75 meters away from roads and away from patch edges. OAs were modeled by creating distance grids using the National Land Cover Database and the Census Bureau's TIGER roads files.

  19. Validation of Water Erosion Prediction Project (WEPP) model for low-volume forest roads

    Science.gov (United States)

    William Elliot; R. B. Foltz; Charlie Luce

    1995-01-01

    Erosion rates of recently graded nongravel forest roads were measured under rainfall simulation on five different soils. The erosion rates observed on 24 forest road erosion plots were compared with values predicted by the Water Erosion Prediction Project (WEPP) Model, Version 93.1. Hydraulic conductivity and soil erodibility values were predicted from methods...

  20. Using maximum entropy modeling to identify and prioritize red spruce forest habitat in West Virginia

    Science.gov (United States)

    Nathan R. Beane; James S. Rentch; Thomas M. Schuler

    2013-01-01

    Red spruce forests in West Virginia are found in island-like distributions at high elevations and provide essential habitat for the endangered Cheat Mountain salamander and the recently delisted Virginia northern flying squirrel. Therefore, it is important to identify restoration priorities of red spruce forests. Maximum entropy modeling was used to identify areas of...

  1. Fuel treatment effects on tree-based forest carbon storage and emissions under modeled wildfire scenarios

    Science.gov (United States)

    M. Hurteau; M. North

    2009-01-01

    Forests are viewed as a potential sink for carbon (C) that might otherwise contribute to climate change. It is unclear, however, how to manage forests with frequent fire regimes to maximize C storage while reducing C emissions from prescribed burns or wildfire. We modeled the effects of eight different fuel treatments on treebased C storage and release over a century,...

  2. Modeling impacts of management on carbon sequestration and trace gas emissions in forested wetland ecosystems

    Science.gov (United States)

    Changsheng Li; Jianbo Cui

    2004-01-01

    A process- based model, Wetland-DNDC, was modified to enhance its capacity to predict the impacts of management practices on carbon sequestration in and trace gas emissions from forested wetland ecosystems. The modifications included parameterization of management practices fe.g., forest harvest, chopping, burning, water management, fertilization, and tree planting),...

  3. A data model for route planning in the case of forest fires

    NARCIS (Netherlands)

    Wang, Z.; Zlatanova, S.; Moreno, A.; Van Oosterom, P.J.M.; Toro, C.

    2013-01-01

    The ability to guide relief vehicles to safety and quickly pass through environments affected by fires is critical in fighting forest fires. In this paper, we focus on route determination in the case of forest fires, and propose a data model that supports finding paths among moving obstacles. This

  4. A mobility constraint model to infer sensor behaviour in forest fire risk monitoring

    NARCIS (Netherlands)

    Ballari, D.E.; Wachowicz, M.; Bregt, A.K.; Manso-Callejo, M.A.

    2012-01-01

    Wireless sensor networks (WSNs) play an important role in forest fire risk monitoring. Various applications are in operation. However, the use of mobile sensors in forest risk monitoring remains largely unexplored. Our research contributes to fill this gap by designing a model which abstracts

  5. Accuracy of an IFSAR-derived digital terrain model under a conifer forest canopy.

    Science.gov (United States)

    Hans-Erik Andersen; Stephen E. Reutebuch; Robert J. McGaughey

    2005-01-01

    Accurate digital terrain models (DTMs) are necessary for a variety of forest resource management applications, including watershed management, timber harvest planning, and fire management. Traditional methods for acquiring topographic data typically rely on aerial photogrammetry, where measurement of the terrain surface below forest canopy is difficult and error prone...

  6. The intrinsic periodic fluctuation of forest: a theoretical model based on diffusion equation

    Science.gov (United States)

    Zhou, J.; Lin, G., Sr.

    2015-12-01

    Most forest dynamic models predict the stable state of size structure as well as the total basal area and biomass in mature forest, the variation of forest stands are mainly driven by environmental factors after the equilibrium has been reached. However, although the predicted power-law size-frequency distribution does exist in analysis of many forest inventory data sets, the estimated distribution exponents are always shifting between -2 and -4, and has a positive correlation with the mean value of DBH. This regular pattern can not be explained by the effects of stochastic disturbances on forest stands. Here, we adopted the partial differential equation (PDE) approach to deduce the systematic behavior of an ideal forest, by solving the diffusion equation under the restricted condition of invariable resource occupation, a periodic solution was gotten to meet the variable performance of forest size structure while the former models with stable performance were just a special case of the periodic solution when the fluctuation frequency equals zero. In our results, the number of individuals in each size class was the function of individual growth rate(G), mortality(M), size(D) and time(T), by borrowing the conclusion of allometric theory on these parameters, the results perfectly reflected the observed "exponent-mean DBH" relationship and also gave a logically complete description to the time varying form of forest size-frequency distribution. Our model implies that the total biomass of a forest can never reach a stable equilibrium state even in the absence of disturbances and climate regime shift, we propose the idea of intrinsic fluctuation property of forest and hope to provide a new perspective on forest dynamics and carbon cycle research.

  7. MODELING SPATIAL TREE PATTERNS IN THE TAPAJÓS FOREST USING INTERFEROMETRIC HEIGHT

    Directory of Open Access Journals (Sweden)

    João R. dos Santos

    2005-04-01

    Full Text Available The spatial distribution of very large trees in primary Amazon forest is extracted from a digital model of interferometric forest height by an approach of local maximum filtering. The spatial point patterns of very large trees are modeled by a series of Markov point process models. Spatial distribution is regular, and interaction decreases with distance; very large trees are shown to exert repulsive interaction with their neighboring very large trees.

  8. Use of Gumbel and Weibull functions to model extreme values of diameter distributions in forest stands

    OpenAIRE

    Gorgoso-Varela, J. Javier; Rojo-Alboreca, Alberto

    2014-01-01

    International audience; & Context Families of the Gumbel (type I), Fréchet (type II) and Weibull (type III) distributions can be combined in the generalized extreme value (GEV) family of distributions. Maximum and minimum values of diameters in forest stands can be used in forest modelling, mainly to define parameters of the functions used in diameter class models as well as in some practical cases, such as modelling maximum diameters for sawing and processing purposes. & Aims The purpose of ...

  9. Towards Linking 3D SAR and Lidar Models with a Spatially Explicit Individual Based Forest Model

    Science.gov (United States)

    Osmanoglu, B.; Ranson, J.; Sun, G.; Armstrong, A. H.; Fischer, R.; Huth, A.

    2017-12-01

    In this study, we present a parameterization of the FORMIND individual-based gap model (IBGM)for old growth Atlantic lowland rainforest in La Selva, Costa Rica for the purpose of informing multisensor remote sensing techniques for above ground biomass techniques. The model was successfully parameterized and calibrated for the study site; results show that the simulated forest reproduces the structural complexity of Costa Rican rainforest based on comparisons with CARBONO inventory plot data. Though the simulated stem numbers (378) slightly underestimated the plot data (418), particularly for canopy dominant intermediate shade tolerant trees and shade tolerant understory trees, overall there was a 9.7% difference. Aboveground biomass (kg/ha) showed a 0.1% difference between the simulated forest and inventory plot dataset. The Costa Rica FORMIND simulation was then used to parameterize a spatially explicit (3D) SAR and lidar backscatter models. The simulated forest stands were used to generate a Look Up Table as a tractable means to estimate aboveground forest biomass for these complex forests. Various combinations of lidar and radar variables were evaluated in the LUT inversion. To test the capability of future data for estimation of forest height and biomass, we considered data of 1) L- (or P-) band polarimetric data (backscattering coefficients of HH, HV and VV); 2) L-band dual-pol repeat-pass InSAR data (HH/HV backscattering coefficients and coherences, height of scattering phase center at HH and HV using DEM or surface height from lidar data as reference); 3) P-band polarimetric InSAR data (canopy height from inversion of PolInSAR data or use the coherences and height of scattering phase center at HH, HV and VV); 4) various height indices from waveform lidar data); and 5) surface and canopy top height from photon-counting lidar data. The methods for parameterizing the remote sensing models with the IBGM and developing Look Up Tables will be discussed. Results

  10. A universal approach to estimate biomass and carbon stock in tropical forests using generic allometric models.

    Science.gov (United States)

    Vieilledent, G; Vaudry, R; Andriamanohisoa, S F D; Rakotonarivo, O S; Randrianasolo, H Z; Razafindrabe, H N; Rakotoarivony, C Bidaud; Ebeling, J; Rasamoelina, M

    2012-03-01

    Allometric equations allow aboveground tree biomass and carbon stock to be estimated from tree size. The allometric scaling theory suggests the existence of a universal power-law relationship between tree biomass and tree diameter with a fixed scaling exponent close to 8/3. In addition, generic empirical models, like Chave's or Brown's models, have been proposed for tropical forests in America and Asia. These generic models have been used to estimate forest biomass and carbon worldwide. However, tree allometry depends on environmental and genetic factors that vary from region to region. Consequently, theoretical models that include too few ecological explicative variables or empirical generic models that have been calibrated at particular sites are unlikely to yield accurate tree biomass estimates at other sites. In this study, we based our analysis on a destructive sample of 481 trees in Madagascar spiny dry and moist forests characterized by a high rate of endemism (> 95%). We show that, among the available generic allometric models, Chave's model including diameter, height, and wood specific gravity as explicative variables for a particular forest type (dry, moist, or wet tropical forest) was the only one that gave accurate tree biomass estimates for Madagascar (R2 > 83%, bias allometric models. When biomass allometric models are not available for a given forest site, this result shows that a simple height-diameter allometry is needed to accurately estimate biomass and carbon stock from plot inventories.

  11. ForestSim Model of Impacts of Smallholder Dynamics: Forested Landscapes of the Upper Peninsula of Michigan

    Directory of Open Access Journals (Sweden)

    Audrey L. Mayer

    2013-01-01

    Full Text Available Many forested landscapes in the United States contain a large number of small private landowners (smallholders. The individual decisions of these smallholders can collectively have a large impact on the structure, composition, and connectivity of forests. While models have been developed to try to understand this large-scale collective impact, few models have incorporated extensive information from individual decision-making. Here we introduce an agent-based model, infused with sociological data from smallholders, overlaid on a GIS layer to represent individual smallholders, and used to simulate the impact of thousands of harvesting decisions. Our preliminary results suggest that certain smallholder characteristics (such as relative smallholder age and education level as well as whether a smallholder is resident or absentee and information flow among owners can radically impact forests at the landscape scale. While still in its preliminary stages, this modeling approach is likely to demonstrate in detail the consequences of decision-making due to changing smallholder demographics or new policies and programs. This approach can help estimate the effectiveness of programs based on landscape-scale programmatic goals and the impact of new policy initiatives.

  12. Modelling long-term water yield effects of forest management in a Norway spruce forest

    Czech Academy of Sciences Publication Activity Database

    Yu, X.; Lamačová, A.; Duffy, Ch.; Krám, P.; Hruška, Jakub; White, T.; Bhatt, G.

    2015-01-01

    Roč. 60, č. 2 (2015), s. 174-191 ISSN 0262-6667 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional support: RVO:67179843 Keywords : Lysina critical zone observatory * PIHM * Norway spruce * forest management Subject RIV: EH - Ecology, Behaviour Impact factor: 2.182, year: 2015

  13. Climate and bark beetle effects on forest productivity -- linking dendroecology with forest landscape modeling

    Science.gov (United States)

    Alec M. Kretchun; E. Louise Loudermilk; Robert M. Scheller; Matthew D. Hurteau; Soumaya Belmecheri

    2016-01-01

    In forested systems throughout the world, climate influences tree growth and aboveground net primary productivity (ANPP). The effects of extreme climate events (i.e., drought) on ANPP can be compounded by biotic factors (e.g., insect outbreaks). Understanding the contribution of each of these influences on growth requires information at...

  14. Modeling some long-term implications of CO2 fertilization for global forests and forest industries

    Science.gov (United States)

    Joseph Buongiorno

    2015-01-01

    Background: This paper explored the long-term, ceteris-paribus effects of potential CO2 fertilization on the globalforest sector. Based on the findings of Norby et al. (PNAS 2005, 102(50)) about forest response to elevated [CO2].Methods:...

  15. Integrating forest growth and harvesting cost models to improve forest management planning

    Science.gov (United States)

    J.E. Baumgras; C.B. LeDoux

    1991-01-01

    Two methods of estimating harvesting revenue--reported stumpage prices - and delivered prices minus estimated harvesting and haul costs were compared by estimating entry cash flows and rotation net present value for three simulated even-aged forest management options that included 1 to 3 thinnings over a 90 year rotation. Revenue estimates derived from stumpage prices...

  16. Including Effects of Water Stress on Dead Organic Matter Decay to a Forest Carbon Model

    Science.gov (United States)

    Kim, H.; Lee, J.; Han, S. H.; Kim, S.; Son, Y.

    2017-12-01

    Decay of dead organic matter is a key process of carbon (C) cycling in forest ecosystems. The change in decay rate depends on temperature sensitivity and moisture conditions. The Forest Biomass and Dead organic matter Carbon (FBDC) model includes a decay sub-model considering temperature sensitivity, yet does not consider moisture conditions as drivers of the decay rate change. This study aimed to improve the FBDC model by including a water stress function to the decay sub-model. Also, soil C sequestration under climate change with the FBDC model including the water stress function was simulated. The water stress functions were determined with data from decomposition study on Quercus variabilis forests and Pinus densiflora forests of Korea, and adjustment parameters of the functions were determined for both species. The water stress functions were based on the ratio of precipitation to potential evapotranspiration. Including the water stress function increased the explained variances of the decay rate by 19% for the Q. variabilis forests and 7% for the P. densiflora forests, respectively. The increase of the explained variances resulted from large difference in temperature range and precipitation range across the decomposition study plots. During the period of experiment, the mean annual temperature range was less than 3°C, while the annual precipitation ranged from 720mm to 1466mm. Application of the water stress functions to the FBDC model constrained increasing trend of temperature sensitivity under climate change, and thus increased the model-estimated soil C sequestration (Mg C ha-1) by 6.6 for the Q. variabilis forests and by 3.1 for the P. densiflora forests, respectively. The addition of water stress functions increased reliability of the decay rate estimation and could contribute to reducing the bias in estimating soil C sequestration under varying moisture condition. Acknowledgement: This study was supported by Korea Forest Service (2017044B10-1719-BB01)

  17. Modelling basin-wide variations in Amazon forest photosynthesis

    Science.gov (United States)

    Mercado, Lina; Lloyd, Jon; Domingues, Tomas; Fyllas, Nikolaos; Patino, Sandra; Dolman, Han; Sitch, Stephen

    2010-05-01

    type parameter values are assigned and assumed invariant with environmental condition but also ii) these models use leaf N as a factor that limit photosynthesis. Instead, since leaf P may also limit photosynthesis of the tropical forest (Reich et al. 2009), we use a more specific description of photosynthetic capacity across the basin based on the model evaluation done in Mercado et al. (2009) in which canopy photosynthetic capacity is related to foliar P but also using the relationships derived between canopy photosynthesis and leaf nutrients (N and P) from measurements in tropical trees (Domingues et al.In review). A study of this kind can inform the global vegetation/climate community as to the need for variability in key model parameters in order to accurately simulate carbon fluxes across the Amazon basin. Baker, T. R., et al. 2004. Increasing biomass in Amazonian forest plots. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 359 (1443):353-365. Phillips, O. L. et al. 2004. Pattern and process in Amazon tree turnover, 1976-2001. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 359 (1443):381-407. Malhi, Y. et al. 2004. The above-ground coarse wood productivity of 104 Neotropical forest plots. Global Change Biology 10 (5):563-591. Mercado, L.M. et al. 2009. Impact of changes in diffuse radiation on the global land carbon sink. Nature 458 (7241), 1014. Cox, P. M. et al. 1998. A canopy conductance and photosynthesis model for use in a GCM land surface scheme. Journal of Hydrology 213 (1-4):79-9 Sitch, S. et al. 2003. Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ dynamic global vegetation model. Global Change Biology 9 (2):161-185. Reich B. R. et al. 2009. Leaf phosphorus influences the photosynhtesis-nitrogen relation: a cross-biome analysis of 314 species. Oecologia, doi 10.1007/s00442-009-1291-3. Domingues, T. et al. In review. Co-limitation of

  18. Understanding the factors that limit restoration success on a recreation-impacted subalpine site

    Science.gov (United States)

    Catherine Zabinski; David Cole

    2000-01-01

    Factors that limit successful revegetation of a subalpine site were studied through a combination of soil assays, greenhouse studies, and field manipulations. Campsite soils had higher available nitrogen, lower microbial community diversity, and lower seed bank density than undisturbed soils. In the greenhouse, there was no significant difference in plant growth on...

  19. Lithosequence of soils and associated vegetation on subalpine range of the Wasatch Plateau, Utah.

    Science.gov (United States)

    James O. Klemmedson; Arthur R. Tiedemann

    1998-01-01

    On degraded subalpine range in Utah, the authors examined the role of soil and parent material nutrients and organic carbon (Corg) in the development of soil and plants on a transect across six strata that formed visible concentric alternating bands of high and low productivity. Relations for soil and parent material phosphorus (P) and sulfur (S) were of particular...

  20. Response of a subalpine grassland to simulated grazing: Aboveground productivity along soil phosphorus gradients

    Science.gov (United States)

    C. Thiel-Egenter; A. C. Risch; M. F. Jurgensen; D. S. Page-Dumroese; B. O. Krusi; M. Schutz

    2007-01-01

    Interactions between grassland ecosystems and vertebrate herbivores are critical for a better understanding of ecosystem processes, but diverge widely in different ecosystems. In this study, we examined plant responses to simulated red deer (Cervus elaphus L.) grazing using clip-plot experiments in a subalpine grassland ecosystem of the Central...

  1. Nutrient status in soil of Ski runs in the sub-alpine belt of Uludag Mountain, Bursa, Turkey.

    Science.gov (United States)

    Guleryuz, Gurcan; Kirmizi, Serap; Arslan, Hulya

    2010-01-01

    Large areas of land are disturbed in sensitive bio-diverse mountain environments by Skiruns. Restoration of vegetation on such disturbed mountain sites may be hampered by soil degradation but the severity and nature of the constraints is not well understood. This study was designed to compare the water holding and nutritional status of soil in three Ski runs which had different construction dates and disturbance levels, and the adjacent undisturbed site in the Abies bommuelleriana forest community in the sub-alpine belt of Uludag Mountain (Bithynian Olympus). The values of soil parameters were depressed in proportion to the disturbance level. Water holding capacity (WHC), total nitrogen (N), organic carbon (C) and calcium (Ca2+), magnesium (Mg2+) and potassium (K+) contents (mg kg(-1) dry weight) of soils in the Ski run which had the highest disturbance level were lower than that of the undisturbed adjacent sites. However the results indicated that the soil parameters were less degraded when secondary vegetation was growing on the disturbed areas.

  2. MODELING URBAN DYNAMICS USING RANDOM FOREST: IMPLEMENTING ROC AND TOC FOR MODEL EVALUATION

    Directory of Open Access Journals (Sweden)

    M. Ahmadlou

    2016-06-01

    Full Text Available The importance of spatial accuracy of land use/cover change maps necessitates the use of high performance models. To reach this goal, calibrating machine learning (ML approaches to model land use/cover conversions have received increasing interest among the scholars. This originates from the strength of these techniques as they powerfully account for the complex relationships underlying urban dynamics. Compared to other ML techniques, random forest has rarely been used for modeling urban growth. This paper, drawing on information from the multi-temporal Landsat satellite images of 1985, 2000 and 2015, calibrates a random forest regression (RFR model to quantify the variable importance and simulation of urban change spatial patterns. The results and performance of RFR model were evaluated using two complementary tools, relative operating characteristics (ROC and total operating characteristics (TOC, by overlaying the map of observed change and the modeled suitability map for land use change (error map. The suitability map produced by RFR model showed 82.48% area under curve for the ROC model which indicates a very good performance and highlights its appropriateness for simulating urban growth.

  3. A synthesis of literature on evaluation of models for policy applications, with implications for forest carbon accounting

    Science.gov (United States)

    Stephen P. Prisley; Michael J. Mortimer

    2004-01-01

    Forest modeling has moved beyond the realm of scientific discovery into the policy arena. The example that motivates this review is the application of models for forest carbon accounting. As negotiations determine the terms under which forest carbon will be accounted, reported, and potentially traded, guidelines and standards are being developed to ensure consistency,...

  4. Effects of lidar pulse density and sample size on a model-assisted approach to estimate forest inventory variables

    Science.gov (United States)

    Jacob Strunk; Hailemariam Temesgen; Hans-Erik Andersen; James P. Flewelling; Lisa Madsen

    2012-01-01

    Using lidar in an area-based model-assisted approach to forest inventory has the potential to increase estimation precision for some forest inventory variables. This study documents the bias and precision of a model-assisted (regression estimation) approach to forest inventory with lidar-derived auxiliary variables relative to lidar pulse density and the number of...

  5. Modeling the impacts of climate variability and hurricane on carbon sequestration in a coastal forested wetland in South Carolina

    Science.gov (United States)

    Zhaohua Dai; Carl C. Trettin; Changsheng Li; Ge Sun; Devendra M. Amatya; Harbin Li

    2013-01-01

    The impacts of hurricane disturbance and climate variability on carbon dynamics in a coastal forested wetland in South Carolina of USA were simulated using the Forest-DNDC model with a spatially explicit approach. The model was validated using the measured biomass before and after Hurricane Hugo and the biomass inventories in 2006 and 2007, showed that the Forest-DNDC...

  6. Biogeochemical modelling vs. tree-ring data - comparison of forest ecosystem productivity estimates

    Science.gov (United States)

    Zorana Ostrogović Sever, Maša; Barcza, Zoltán; Hidy, Dóra; Paladinić, Elvis; Kern, Anikó; Marjanović, Hrvoje

    2017-04-01

    Forest ecosystems are sensitive to environmental changes as well as human-induce disturbances, therefore process-based models with integrated management modules represent valuable tool for estimating and forecasting forest ecosystem productivity under changing conditions. Biogeochemical model Biome-BGC simulates carbon, nitrogen and water fluxes, and it is widely used for different terrestrial ecosystems. It was modified and parameterised by many researchers in the past to meet the specific local conditions. In this research, we used recently published improved version of the model Biome-BGCMuSo (BBGCMuSo), with multilayer soil module and integrated management module. The aim of our research is to validate modelling results of forest ecosystem productivity (NPP) from BBGCMuSo model with observed productivity estimated from an extensive dataset of tree-rings. The research was conducted in two distinct forest complexes of managed Pedunculate oak in SE Europe (Croatia), namely Pokupsko basin and Spačva basin. First, we parameterized BBGCMuSo model at a local level using eddy-covariance (EC) data from Jastrebarsko EC site. Parameterized model was used for the assessment of productivity on a larger scale. Results of NPP assessment with BBGCMuSo are compared with NPP estimated from tree ring data taken from trees on over 100 plots in both forest complexes. Keywords: Biome-BGCMuSo, forest productivity, model parameterization, NPP, Pedunculate oak

  7. Modeling seasonal surface temperature variations in secondary tropical dry forests

    Science.gov (United States)

    Cao, Sen; Sanchez-Azofeifa, Arturo

    2017-10-01

    Secondary tropical dry forests (TDFs) provide important ecosystem services such as carbon sequestration, biodiversity conservation, and nutrient cycle regulation. However, their biogeophysical processes at the canopy-atmosphere interface remain unknown, limiting our understanding of how this endangered ecosystem influences, and responds to the ongoing global warming. To facilitate future development of conservation policies, this study characterized the seasonal land surface temperature (LST) behavior of three successional stages (early, intermediate, and late) of a TDF, at the Santa Rosa National Park (SRNP), Costa Rica. A total of 38 Landsat-8 Thermal Infrared Sensor (TIRS) data and the Surface Reflectance (SR) product were utilized to model LST time series from July 2013 to July 2016 using a radiative transfer equation (RTE) algorithm. We further related the LST time series to seven vegetation indices which reflect different properties of TDFs, and soil moisture data obtained from a Wireless Sensor Network (WSN). Results showed that the LST in the dry season was 15-20 K higher than in the wet season at SRNP. We found that the early successional stages were about 6-8 K warmer than the intermediate successional stages and were 9-10 K warmer than the late successional stages in the middle of the dry season; meanwhile, a minimum LST difference (0-1 K) was observed at the end of the wet season. Leaf phenology and canopy architecture explained most LST variations in both dry and wet seasons. However, our analysis revealed that it is precipitation that ultimately determines the LST variations through both biogeochemical (leaf phenology) and biogeophysical processes (evapotranspiration) of the plants. Results of this study could help physiological modeling studies in secondary TDFs.

  8. National forest economic clusters: a new model for assessing national-forest-based natural resources products and services.

    Science.gov (United States)

    Thomas D. Rojas

    2007-01-01

    National forest lands encompass numerous rural and urban communities. Some national-forest-based communities lie embedded within national forests, and others reside just outside the official boundaries of national forests. The urban and rural communities within or near national forest lands include a wide variety of historical traditions and cultural values that affect...

  9. Impact of Temperature and Hydrological Residence Time on the Fate and Transport of Iron and Organic Carbon in Subalpine Wetlands

    Science.gov (United States)

    Schneider, L. M.; Borch, T.; Rhoades, C.; Pallud, C. E.

    2015-12-01

    Wetlands contain one third of the planet's soil carbon (C) and are characterized by markedly different chemical and physical environments than terrestrial ecosystems. The hydrologic residence time and temperature in wetlands influences their redox conditions and thus biogeochemical reaction rates. In these environments, transformation and movement of C and iron (Fe) are closely linked due to the sorption of organic C by solid Fe(III)-phases. Therefore, changes in Fe biogeochemical cycling will influence the size and turnover rate of soil C pools, which could negatively impact water quality and C storage. We examined the effects of hydrologic residence time and temperature on reduction of autochtonous Fe(III)-oxides. Fe(II)-export rates, used as a lower bound for bulk Fe(III)-reduction rates, and dissolved organic carbon (DOC) export rates were measured on intact mineral soil cores using flow-through reactor experiments exposed to temperatures based on mean annual conditions (6°, 12°, and 18°C). Soils were from a slope and a depressional subalpine wetland (USDA Fraser Experimental Forest, CO, USA), characterized by different hydrologic residence times, were compared. In the depressional wetland we observed the shallower soil depths have higher overall Fe(II)-export rates than the deeper soil depths. As temperature increases, Fe(II)-export rate increases, with a more than doubling in magnitude from 12 to 18° C. In comparing sites that are continuously inundated to those that are seasonally inundated, surprisingly we see higher Fe(II)-export rates in the seasonally inundated sites for all temperatures and depths. In the slope wetland we observed an opposite trend with depth and with temperature, with Fe(II)-export rates declining by almost an order of magnitude between 6 and 12°C. In addition, our results showed a positive correlation between Fe(II)-export rates and DOC export rates suggesting Fe(III)-reduction exerts a biogeochemical control on water quality

  10. Net primary productivity of subalpine meadows in Yosemite National Park in relation to climate variability

    Science.gov (United States)

    Moore, Peggy E.; Van Wagtendonk, Jan W.; Yee, Julie L.; McClaran, Mitchel P.; Cole, David N.; McDougald, Neil K.; Brooks, Matthew L.

    2013-01-01

    Subalpine meadows are some of the most ecologically important components of mountain landscapes, and primary productivity is important to the maintenance of meadow functions. Understanding how changes in primary productivity are associated with variability in moisture and temperature will become increasingly important with current and anticipated changes in climate. Our objective was to describe patterns and variability in aboveground live vascular plant biomass in relation to climatic factors. We harvested aboveground biomass at peak growth from four 64-m2 plots each in xeric, mesic, and hydric meadows annually from 1994 to 2000. Data from nearby weather stations provided independent variables of spring snow water content, snow-free date, and thawing degree days for a cumulative index of available energy. We assembled these climatic variables into a set of mixed effects analysis of covariance models to evaluate their relationships with annual aboveground net primary productivity (ANPP), and we used an information theoretic approach to compare the quality of fit among candidate models. ANPP in the xeric meadow was negatively related to snow water content and thawing degree days and in the mesic meadow was negatively related to snow water content. Relationships between ANPP and these 2 covariates in the hydric meadow were not significant. Increasing snow water content may limit ANPP in these meadows if anaerobic conditions delay microbial activity and nutrient availability. Increased thawing degree days may limit ANPP in xeric meadows by prematurely depleting soil moisture. Large within-year variation of ANPP in the hydric meadow limited sensitivity to the climatic variables. These relationships suggest that, under projected warmer and drier conditions, ANPP will increase in mesic meadows but remain unchanged in xeric meadows because declines associated with increased temperatures would offset the increases from decreased snow water content.

  11. Testing of models of stomatal ozone fluxes with field measurements in a mixed Mediterranean forest

    Czech Academy of Sciences Publication Activity Database

    Fares, S.; Matteucci, G.; Mugnozza, S.; Morani, A.; Calfapietra, Carlo; Salvatori, E.; Fusaro, L.; Manes, F.; Loreto, F.

    2013-01-01

    Roč. 67, MAR (2013), s. 242-251 ISSN 1352-2310 Institutional support: RVO:67179843 Keywords : Ozone fluxes * Stomatal conductance models * GPP * Mediterranean forest Subject RIV: EH - Ecology, Behaviour Impact factor: 3.062, year: 2013

  12. A compartment model of plutonium dynamics in a deciduous forest ecosystem

    International Nuclear Information System (INIS)

    Garten, C.T. Jr.; Gardner, R.H.; Dahlman, R.C.

    1978-01-01

    A linear compartment donor-controlled model was designed to describe and simulate the behaviour of plutonium ( 239 , 240 Pu) in a contaminated deciduous forest ecosystem at Oak Ridge, Tennessee. At steady states predicted by the model, less than 0.25% of the Pu in the ecosystem resides in forest biota. Soil is the major repository of Pu in the forest, and reciprocal exchanges of Pu between soil and litter or soil and tree roots were dominant transfers affecting the ecosystem distribution of Pu. Variation in predicted steady state amounts of Pu in the forest, given variability in the model parameters, indicated that ones ability to develop reliable models of Pu transport in ecosystems will improve with greater precision in data from natural environments and a better understanding of sources of variation in Pu data. (author)

  13. Hydrologic flow path development varies by aspect during spring snowmelt in complex subalpine terrain

    Directory of Open Access Journals (Sweden)

    R. W. Webb

    2018-01-01

    Full Text Available In many mountainous regions around the world, snow and soil moisture are key components of the hydrologic cycle. Preferential flow paths of snowmelt water through snow have been known to occur for years with few studies observing the effect on soil moisture. In this study, statistical analysis of the topographical and hydrological controls on the spatiotemporal variability of snow water equivalent (SWE and soil moisture during snowmelt was undertaken at a subalpine forested setting with north, south, and flat aspects as a seasonally persistent snowpack melts. We investigated if evidence of preferential flow paths in snow can be observed and the effect on soil moisture through measurements of snow water equivalent and near-surface soil moisture, observing how SWE and near-surface soil moisture vary on hillslopes relative to the toes of hillslopes and flat areas. We then compared snowmelt infiltration beyond the near-surface soil between flat and sloping terrain during the entire snowmelt season using soil moisture sensor profiles. This study was conducted during varying snowmelt seasons representing above-normal, relatively normal, and below-normal snow seasons in northern Colorado. Evidence is presented of preferential meltwater flow paths at the snow–soil interface on the north-facing slope causing increases in SWE downslope and less infiltration into the soil at 20 cm depth; less association is observed in the near-surface soil moisture (top 7 cm. We present a conceptualization of the meltwater flow paths that develop based on slope aspect and soil properties. The resulting flow paths are shown to divert at least 4 % of snowmelt laterally, accumulating along the length of the slope, to increase the snow water equivalent by as much as 170 % at the base of a north-facing hillslope. Results from this study show that snow acts as an extension of the vadose zone during spring snowmelt and future hydrologic investigations will benefit

  14. Aboveground Biomass Modeling from Field and LiDAR Data in Brazilian Amazon Tropical Rain Forest

    Science.gov (United States)

    Silva, C. A.; Hudak, A. T.; Vierling, L. A.; Keller, M. M.; Klauberg Silva, C. K.

    2015-12-01

    Tropical forests are an important component of global carbon stocks, but tropical forest responses to climate change are not sufficiently studied or understood. Among remote sensing technologies, airborne LiDAR (Light Detection and Ranging) may be best suited for quantifying tropical forest carbon stocks. Our objective was to estimate aboveground biomass (AGB) using airborne LiDAR and field plot data in Brazilian tropical rain forest. Forest attributes such as tree density, diameter at breast height, and heights were measured at a combination of square plots and linear transects (n=82) distributed across six different geographic zones in the Amazon. Using previously published allometric equations, tree AGB was computed and then summed to calculate total AGB at each sample plot. LiDAR-derived canopy structure metrics were also computed at each sample plot, and random forest regression modelling was applied to predict AGB from selected LiDAR metrics. The LiDAR-derived AGB model was assessed using the random forest explained variation, adjusted coefficient of determination (Adj. R²), root mean square error (RMSE, both absolute and relative) and BIAS (both absolute and relative). Our findings showed that the 99th percentile of height and height skewness were the best LiDAR metrics for AGB prediction. The AGB model using these two best predictors explained 59.59% of AGB variation, with an Adj. R² of 0.92, RMSE of 33.37 Mg/ha (20.28%), and bias of -0.69 (-0.42%). This study showed that LiDAR canopy structure metrics can be used to predict AGC stocks in Tropical Forest with acceptable precision and accuracy. Therefore, we conclude that there is good potential to monitor carbon sequestration in Brazilian Tropical Rain Forest using airborne LiDAR data, large field plots, and the random forest algorithm.

  15. iTree-Hydro: Snow hydrology update for the urban forest hydrology model

    Science.gov (United States)

    Yang Yang; Theodore A. Endreny; David J. Nowak

    2011-01-01

    This article presents snow hydrology updates made to iTree-Hydro, previously called the Urban Forest Effects—Hydrology model. iTree-Hydro Version 1 was a warm climate model developed by the USDA Forest Service to provide a process-based planning tool with robust water quantity and quality predictions given data limitations common to most urban areas. Cold climate...

  16. Evaluating the impacts of slope aspect on forest dynamic succession in Northwest China based on FAREAST model

    Science.gov (United States)

    Hu, Shanshan; Ma, Jianyong; Shugart, Herman H.; Yan, Xiaodong

    2018-03-01

    Mountain forests provide the main water resources and lumber for Northwest China. The understanding of the differences in forests growing among individual slope aspects in mountainous regions is of great significance to the wise management and planning of these natural systems. The aim of this study was to investigate the impacts of slope aspect on forest dynamic succession in Northwest China by using the dynamic forest succession model (FAREAST). First, the simulated forest composition and vertical forest zonation produced by the model were compared against recorded data in three sub-regions of the Altai Mountains. The FAREAST model accurately reproduced the vertical zonation, forest composition, growth curves of the dominant species (Larix sibirica), and forest biomass in the Altai Mountains. Transitions along the forest zones of the Altai Mountains averaged about a 400 m difference between the northern and southern sites. Biomass for forests on north-facing slopes were 11.0, 15.3 and 55.9 t C ha-1 higher than for south-facing slopes in the Northeast, Central and Southeast sub-regions, respectively. Second, our analyses showed that the FAREAST model can be used to predict dynamic forest succession in Northwest China under the influence of slope and aspect. In the Altai Mountains, the north-facing slopes supported the best forest growth, followed by the west- and east-facing slopes. South-facing slopes consistently exhibited the lowest growth, biomass storage and forest diversity.

  17. Comparing ALS and Image-Based Point Cloud Metrics and Modelled Forest Inventory Attributes in a Complex Coastal Forest Environment

    Directory of Open Access Journals (Sweden)

    Joanne C. White

    2015-10-01

    Full Text Available Digital aerial photogrammetry (DAP is emerging as an alternate data source to airborne laser scanning (ALS data for three-dimensional characterization of forest structure. In this study we compare point cloud metrics and plot-level model estimates derived from ALS data and an image-based point cloud generated using semi-global matching (SGM for a complex, coastal forest in western Canada. Plot-level estimates of Lorey’s mean height (H, basal area (G, and gross volume (V were modelled using an area-based approach. Metrics and model outcomes were evaluated across a series of strata defined by slope and canopy cover, as well as by image acquisition date. We found statistically significant differences between ALS and SGM metrics for all strata for five of the eight metrics we used for model development. We also found that the similarity between metrics from the two data sources generally increased with increasing canopy cover, particularly for upper canopy metrics, whereas trends across slope classes were less consistent. Model outcomes from ALS and SGM were comparable. We found the greatest difference in model outcomes was for H (ΔRMSE% = 5.04%. By comparison, ΔRMSE% was 2.33% for G and 3.63% for V. We did not discern any corresponding trends in model outcomes across slope and canopy cover strata, or associated with different image acquisition dates.

  18. Moderate effects of reforestation with Norway spruce (Picea abies) on carbon storage and turnover in a Swiss sub-alpine pasture

    Science.gov (United States)

    Hiltbrunner, D.; Hagedorn, F.; Niklaus, P. A.; Zimmermann, S.; Schmidt, M. W. I.

    2012-04-01

    In alpine regions the forested area is strongly increasing through woody plant encroachment on abandoned pastures or by man-made afforestations. These natural or artificial reforestations, in fact, have several implications on the nutrient cycling between plants and soils and thus, are likely to affect carbon turnover. Although afforestations are to be accounted as a sink according to the Kyoto protocol, there are still uncertainties about their effects on the soil carbon storage. In the present study, we assessed soils under pasture, an adjacent chronosequence of spruce afforestations (25-45 years) and a mature spruce forest (older than 120 years) on a homogenous slope in a Swiss sub-alpine ecosystem. While the soil bulk densities were not affected by the land use change, carbon concentrations in the mineral soil decreased 25-45 years after tree establishment. However, no differences between pasture and the mature forest were apparent, indicating that the C-loss after land use conversion was only transient. Up to 2.5kg m-2 C was additionally stored in the organic layer of the oldest stands, resulting in a net C gain in the old forest soils. C:N-ratios of the soil organic matter (SOM) considerably increased with stand age in the uppermost soil layer, displaying the distinct chemical composition of the plant input. In accordance, a shift of the δ13C natural abundance of the SOM in the uppermost mineral layer towards a less negative signal was observed with tree development. The abundance of soil microorganisms, as identified by their phospholipid fatty acids (PLFA), was only moderately affected by vegetation type in the mineral soils. In contrast, a strong alteration of the microbial community composition with a decreasing proportion of fungi from the organic layers to the uppermost mineral layer was observable. Our results show that afforestation with spruce trees on an extensively used sub-alpine pasture only led to a transient loss of C in the mineral soils. In

  19. Model-based assessments of climate change effects on forests. A critical review

    Energy Technology Data Exchange (ETDEWEB)

    Loehle, Craig [Environmental Research Division, Argonne National Laboratory, Argonne, IL (United States); LeBlanc, David [Department of Biology, Ball State University, Muncie, IN (United States)

    1996-07-24

    A number of studies based on forest simulation models predict substantial alteration of forest composition, forest dieback, or even loss of forest cover in response to increased temperatures. However, the structure of these computer models may cause them to overemphasize the role of climate in controlling tree growth and mortality. Model functions that represent the influence of climate on tree growth are based on the geographic range limits of a species, predicting maximal growth in the center of the range and zero growth (100% mortality) at the range limits and beyond. This modeling approach ignores the fact that the geographic range of a species reflects the influence of both climate and other environmental factors, including competition with other tree species, soil characteristics, barriers to dispersal, and distributions of pests and pathogens. These climate-response functions in forest simulation models implicitly assume that tree species occur in all environments where it is possible for them to survive (their fundamental niche or potential habitat) and that these potential habitats are entirely defined by climate. Hence, any alteration of climate must result in a fairly rapid decline of species near their range limits and rapid alteration of forest composition and structure. The climate-response functions that lead to these unrealistic conclusions have no basis in plant physiology or actual measurements of tree responses to climate stressors. There is substantial evidence, however, that some tree species can survive, and even thrive, in climatic conditions outside their present range limits. It is proposed to reformulate forest simulation models with more realistic representations of growth responses to temperature, moisture, mortality, and dispersal. Only when these models more accurately reflect the physiological bases of the responses of tree species to climate variables can they be used to simulate responses of forests to rapid changes in climate.

  20. Intelligent Model Management in a Forest Ecosystem Management Decision Support System

    Science.gov (United States)

    Donald Nute; Walter D. Potter; Frederick Maier; Jin Wang; Mark Twery; H. Michael Rauscher; Peter Knopp; Scott Thomasma; Mayukh Dass; Hajime Uchiyama

    2002-01-01

    Decision making for forest ecosystem management can include the use of a wide variety of modeling tools. These tools include vegetation growth models, wildlife models, silvicultural models, GIS, and visualization tools. NED-2 is a robust, intelligent, goal-driven decision support system that integrates tools in each of these categories. NED-2 uses a blackboard...

  1. Light Competition and Carbon Partitioning-Allocation in an improved Forest Ecosystem Model

    Science.gov (United States)

    Collalti, Alessio; Santini, Monia; Valentini Valentini, Riccardo

    2010-05-01

    In Italy about 100.000 km2 are covered by forests. This surface is the 30% of the whole national land and this shows how the forests are important both for socio-economic and for environmental aspects. Forests changes affect a delicate balance that involve not only vegetation components but also bio-geochemical cycles and global climate. The knowledge of the amount of Carbon sequestered by forests represents a precious information for their sustainable management in the framework of climate changes. Primary studies in terms of model about this important issue, has been done through Forest Ecosystem Model (FEM), well known and validated as 3PG (Landsberg et Waring, 1997; Sands 2004). It is based on light use efficiency approach at the canopy level. The present study started from the original model 3PG, producing an improved version that uses many of explicit formulations of all relevant ecophysiological processes but makes it able to be applied for natural forests. The mutual interaction of forest growth and light conditions causes vertical and horizontal differentiation in the natural forest mosaic. Only ecophysiological parameters which can be either directly measured or estimates with reasonable certainty are used. The model has been written in C language and has been created considering a tri-dimensional cell structure with different vertical layers depending on the forest type that has to be simulated. This 3PG 'improved' version enable to work on multi-layer and multi-species forests type with cell resolution of one hectare for the typical Italian forest species. The multi-layer version is the result of the implementation and development of Lambert-Beer law for the estimation of intercepted, absorbed and transmitted light through different storeys of the forest. It is possible estimates, for each storey, a Par value (Photosynthetic Active Radiation) through Leaf Area Index (LAI), Light Extinction Coefficient and cell Canopy Cover using a "Big Leaf" approach

  2. Final Progress Report on Model-Based Diagnosis of Soil Limitations to Forest Productivity

    Energy Technology Data Exchange (ETDEWEB)

    Luxmoore, R.J.

    2004-08-30

    This project was undertaken in support of the forest industry to link modeling of nutrients and productivity with field research to identify methods for enhancing soil quality and forest productivity and for alleviating soil limitations to sustainable forest productivity. The project consisted of a series of related tasks, including (1) simulation of changes in biomass and soil carbon with nitrogen fertilization, (2) development of spreadsheet modeling tools for soil nutrient availability and tree nutrient requirements, (3) additional modeling studies, and (4) evaluation of factors involved in the establishment and productivity of southern pine plantations in seasonally wet soils. This report also describes the two Web sites that were developed from the research to assist forest managers with nutrient management of Douglas-fir and loblolly pine plantations.

  3. To Model for the Georeferenciation of the Colonization of the Forest to Future

    International Nuclear Information System (INIS)

    Angel Sanint, Enrique; Castano Posada, Carlos Mario

    2003-01-01

    A mathematical model for the future geographical projection of the forest colonization process is proposed. The model allows the estimation of future forest areas and their geographical location, in such a way that it is possible to create a probable image of the forest coverage at a given future date. The model is based on the preservation of historical statistical parameters through the use of multi-temporal analysis of satellite images. The developed projection method is applied to San Vicente del Chucuri Santander, Colombia) using four Land sat satellite images from 1977, 1985, 1991 and 1998. The statistical behavior of the colonization process is established, to produce a future forest image for the year 2005 in the study area

  4. Quantification of Groundwater Discharge in a Subalpine Stream Using Radon-222

    Directory of Open Access Journals (Sweden)

    Elizabeth Avery

    2018-01-01

    Full Text Available During the dry months of the water year in Mediterranean climates, groundwater influx is essential to perennial streams for sustaining ecosystem health and regulating water temperature. Predicted earlier peak flow due to climate change may result in decreased baseflow and the transformation of perennial streams to intermittent streams. In this study, naturally occurring radon-222 (222Rn was used as a tracer of groundwater influx to Martis Creek, a subalpine stream near Lake Tahoe, CA. Groundwater 222Rn is estimated based on measurements of 222Rn activity in nearby deep wells and springs. To determine the degassing constant (needed for quantification of water and gas flux, an extrinsic tracer, xenon (Xe, was introduced to the stream and monitored at eight downstream locations. The degassing constant for 222Rn is based on the degassing constant for Xe, and was determined to be 1.9–9.0 m/day. Applying a simple model in which stream 222Rn activity is a balance between the main 222Rn source (groundwater and sink (volatilization, the influx in reaches of the upstream portion of Martis Creek was calculated to be <1 to 15 m3/day/m, which cumulatively constitutes a significant portion of the stream discharge. Experiments constraining 222Rn emanation from hyporheic zone sediments suggest that this should be considered a maximum rate of influx. Groundwater influx is typically difficult to identify and quantify, and the method employed here is useful for identifying locations for focused stream flow measurements, for formulating a water budget, and for quantifying streamwater–groundwater interaction.

  5. A study on the use and modeling of geographical information system for combating forest crimes: an assessment of crimes in the eastern Mediterranean forests.

    Science.gov (United States)

    Pak, Mehmet; Gülci, Sercan; Okumuş, Arif

    2018-01-06

    This study focuses on the geo-statistical assessment of spatial estimation models in forest crimes. Used widely in the assessment of crime and crime-dependent variables, geographic information system (GIS) helps the detection of forest crimes in rural regions. In this study, forest crimes (forest encroachment, illegal use, illegal timber logging, etc.) are assessed holistically and modeling was performed with ten different independent variables in GIS environment. The research areas are three Forest Enterprise Chiefs (Baskonus, Cinarpinar, and Hartlap) affiliated to Kahramanmaras Forest Regional Directorate in Kahramanmaras. An estimation model was designed using ordinary least squares (OLS) and geographically weighted regression (GWR) methods, which are often used in spatial association. Three different models were proposed in order to increase the accuracy of the estimation model. The use of variables with a variance inflation factor (VIF) value of lower than 7.5 in Model I and lower than 4 in Model II and dependent variables with significant robust probability values in Model III are associated with forest crimes. Afterwards, the model with the lowest corrected Akaike Information Criterion (AIC c ), and the highest R 2 value was selected as the comparison criterion. Consequently, Model III proved to be more accurate compared to other models. For Model III, while AIC c was 328,491 and R 2 was 0.634 for OLS-3 model, AIC c was 318,489 and R 2 was 0.741 for GWR-3 model. In this respect, the uses of GIS for combating forest crimes provide different scenarios and tangible information that will help take political and strategic measures.

  6. Modelling long term impacts of environmental change on mid- and high-latitude European forests and options for adaptive forest management

    NARCIS (Netherlands)

    Pussinen, A.; Nabuurs, G.J.M.M.; Wieggers, H.J.J.; Reinds, G.J.; Wamelink, G.W.W.; Kros, J.; Mol-Dijkstra, J.P.; Vries, de W.

    2009-01-01

    The process based model SMART–SUMO–WATBAL was applied to 166 intensive monitoring forest plots of mid- and high-latitude Europe to evaluate the effects of expected future changes in carbon dioxide concentration, temperature, precipitation and nitrogen deposition on forest growth (net annual

  7. Multiscale modeling of spring phenology across Deciduous Forests in the Eastern United States.

    Science.gov (United States)

    Melaas, Eli K; Friedl, Mark A; Richardson, Andrew D

    2016-02-01

    Phenological events, such as bud burst, are strongly linked to ecosystem processes in temperate deciduous forests. However, the exact nature and magnitude of how seasonal and interannual variation in air temperatures influence phenology is poorly understood, and model-based phenology representations fail to capture local- to regional-scale variability arising from differences in species composition. In this paper, we use a combination of surface meteorological data, species composition maps, remote sensing, and ground-based observations to estimate models that better represent how community-level species composition affects the phenological response of deciduous broadleaf forests to climate forcing at spatial scales that are typically used in ecosystem models. Using time series of canopy greenness from repeat digital photography, citizen science data from the USA National Phenology Network, and satellite remote sensing-based observations of phenology, we estimated and tested models that predict the timing of spring leaf emergence across five different deciduous broadleaf forest types in the eastern United States. Specifically, we evaluated two different approaches: (i) using species-specific models in combination with species composition information to 'upscale' model predictions and (ii) using repeat digital photography of forest canopies that observe and integrate the phenological behavior of multiple representative species at each camera site to calibrate a single model for all deciduous broadleaf forests. Our results demonstrate variability in cumulative forcing requirements and photoperiod cues across species and forest types, and show how community composition influences phenological dynamics over large areas. At the same time, the response of different species to spatial and interannual variation in weather is, under the current climate regime, sufficiently similar that the generic deciduous forest model based on repeat digital photography performed

  8. Modeling Carbon Storage across a Heterogeneous Mixed Temperate Forest: The Influence of Forest Type Specificity on Regional-scale Carbon Storage Estimates

    Science.gov (United States)

    Adams, A.; Pontius, J.; Galford, G. L.; Gudex-Cross, D.; Merrill, S.

    2017-12-01

    Accurately assessing forest carbon storage is critical to understanding global carbon cycles and the effects of land cover changes on ecological processes. However, calculations of regional-scale forest carbon storage typically rely on maps that reflect only broad forest classes. How species-specific differences in carbon storage may affect assessments of forest carbon in heterogeneous forests is largely unexplored. We used new maps of tree species relative basal area, degraded to various levels of species composition specificity, to examine whether species-specific information improves the accuracy of forest carbon estimates in the northeastern U.S. The forest classification schemes tested, from highest to lowest specificity, were: 1) relative basal area by species, 2) species association classes, and 3) general forest types per IPCC (2006) guidelines. The level of forest type specificity did influence results. Generally, lower carbon storage estimates were generated by models using higher-specificity forest classifications. The two most specific models, with mean carbon storage values of 102-107 Mg/ha, were the most accurate compared to field validation plots and best reflected the finer resolution spatial pattern of carbon storage across the landscape. Northeastern forests may be storing more carbon than previously thought; our species-specific regional estimates are higher than both U.S. Forest Service-generated estimates (84-90 Mg C/ha) and IPCC carbon storage guideline best estimates (75 Mg C/ha). Our results suggest that considering carbon storage capacities of different tree species can improve accuracy of carbon assessments, and better reflect carbon storage patterns across heterogeneous landscapes. However, stand age heavily influences carbon storage values, and more work is needed to improve landscape-scale stand age data.

  9. Reviews and syntheses: Field data to benchmark the carbon cycle models for tropical forests

    Science.gov (United States)

    Clark, Deborah A.; Asao, Shinichi; Fisher, Rosie; Reed, Sasha; Reich, Peter B.; Ryan, Michael G.; Wood, Tana E.; Yang, Xiaojuan

    2017-10-01

    For more accurate projections of both the global carbon (C) cycle and the changing climate, a critical current need is to improve the representation of tropical forests in Earth system models. Tropical forests exchange more C, energy, and water with the atmosphere than any other class of land ecosystems. Further, tropical-forest C cycling is likely responding to the rapid global warming, intensifying water stress, and increasing atmospheric CO2 levels. Projections of the future C balance of the tropics vary widely among global models. A current effort of the modeling community, the ILAMB (International Land Model Benchmarking) project, is to compile robust observations that can be used to improve the accuracy and realism of the land models for all major biomes. Our goal with this paper is to identify field observations of tropical-forest ecosystem C stocks and fluxes, and of their long-term trends and climatic and CO2 sensitivities, that can serve this effort. We propose criteria for reference-level field data from this biome and present a set of documented examples from old-growth lowland tropical forests. We offer these as a starting point towards the goal of a regularly updated consensus set of benchmark field observations of C cycling in tropical forests.

  10. Reviews and syntheses: Field data to benchmark the carbon cycle models for tropical forests

    Science.gov (United States)

    Clark, Deborah A.; Asao, Shinichi; Fisher, Rosie A.; Reed, Sasha C.; Reich, Peter B.; Ryan, Michael G.; Wood, Tana E.; Yang, Xiaojuan

    2017-01-01

    For more accurate projections of both the global carbon (C) cycle and the changing climate, a critical current need is to improve the representation of tropical forests in Earth system models. Tropical forests exchange more C, energy, and water with the atmosphere than any other class of land ecosystems. Further, tropical-forest C cycling is likely responding to the rapid global warming, intensifying water stress, and increasing atmospheric CO2 levels. Projections of the future C balance of the tropics vary widely among global models. A current effort of the modeling community, the ILAMB (International Land Model Benchmarking) project, is to compile robust observations that can be used to improve the accuracy and realism of the land models for all major biomes. Our goal with this paper is to identify field observations of tropical-forest ecosystem C stocks and fluxes, and of their long-term trends and climatic and CO2 sensitivities, that can serve this effort. We propose criteria for reference-level field data from this biome and present a set of documented examples from old-growth lowland tropical forests. We offer these as a starting point towards the goal of a regularly updated consensus set of benchmark field observations of C cycling in tropical forests.

  11. Reviews and syntheses: Field data to benchmark the carbon cycle models for tropical forests

    Directory of Open Access Journals (Sweden)

    D. A. Clark

    2017-10-01

    Full Text Available For more accurate projections of both the global carbon (C cycle and the changing climate, a critical current need is to improve the representation of tropical forests in Earth system models. Tropical forests exchange more C, energy, and water with the atmosphere than any other class of land ecosystems. Further, tropical-forest C cycling is likely responding to the rapid global warming, intensifying water stress, and increasing atmospheric CO2 levels. Projections of the future C balance of the tropics vary widely among global models. A current effort of the modeling community, the ILAMB (International Land Model Benchmarking project, is to compile robust observations that can be used to improve the accuracy and realism of the land models for all major biomes. Our goal with this paper is to identify field observations of tropical-forest ecosystem C stocks and fluxes, and of their long-term trends and climatic and CO2 sensitivities, that can serve this effort. We propose criteria for reference-level field data from this biome and present a set of documented examples from old-growth lowland tropical forests. We offer these as a starting point towards the goal of a regularly updated consensus set of benchmark field observations of C cycling in tropical forests.

  12. Polarimetric SAR Interferometry based modeling for tree height and aboveground biomass retrieval in a tropical deciduous forest

    Science.gov (United States)

    Kumar, Shashi; Khati, Unmesh G.; Chandola, Shreya; Agrawal, Shefali; Kushwaha, Satya P. S.

    2017-08-01

    The regulation of the carbon cycle is a critical ecosystem service provided by forests globally. It is, therefore, necessary to have robust techniques for speedy assessment of forest biophysical parameters at the landscape level. It is arduous and time taking to monitor the status of vast forest landscapes using traditional field methods. Remote sensing and GIS techniques are efficient tools that can monitor the health of forests regularly. Biomass estimation is a key parameter in the assessment of forest health. Polarimetric SAR (PolSAR) remote sensing has already shown its potential for forest biophysical parameter retrieval. The current research work focuses on the retrieval of forest biophysical parameters of tropical deciduous forest, using fully polarimetric spaceborne C-band data with Polarimetric SAR Interferometry (PolInSAR) techniques. PolSAR based Interferometric Water Cloud Model (IWCM) has been used to estimate aboveground biomass (AGB). Input parameters to the IWCM have been extracted from the decomposition modeling of SAR data as well as PolInSAR coherence estimation. The technique of forest tree height retrieval utilized PolInSAR coherence based modeling approach. Two techniques - Coherence Amplitude Inversion (CAI) and Three Stage Inversion (TSI) - for forest height estimation are discussed, compared and validated. These techniques allow estimation of forest stand height and true ground topography. The accuracy of the forest height estimated is assessed using ground-based measurements. PolInSAR based forest height models showed enervation in the identification of forest vegetation and as a result height values were obtained in river channels and plain areas. Overestimation in forest height was also noticed at several patches of the forest. To overcome this problem, coherence and backscatter based threshold technique is introduced for forest area identification and accurate height estimation in non-forested regions. IWCM based modeling for forest

  13. Assessing heat fluxes and water quality trends in subalpine lakes from EO

    Science.gov (United States)

    Cazzaniga, Ilaria; Giardino, Claudia; Bresciani, Mariano; Elli, Chiara; Valerio, Giulia; Pilotti, Marco

    2017-04-01

    Lakes play a fundamental role in providing ecosystem services such as water supplying, hydrological regulation, climate change mitigation, touristic recreation (Schallenberg et al., 2013). Preserving and improving of quality of lakes waters, which is a function of either both natural and human influences, is therefore an important action to be considered. Remote Sensing techniques are spreading as useful instrument for lakes, by integrating classical in situ limnological measurements to frequent and synoptic monitoring capabilities. Within this study, Earth Observation data are exploited for understanding the temporal changes of water quality parameters over a decade, as well as for measuring the surface energy fluxes in recent years in deep clear lakes in the European subalpine ecoregion. According to Pareth et al. (2016), subalpine lakes are showing a clear response to climate change with an increase of 0.017 °C /year of lake surface temperature, whilst the human activities contribute to produce a large impact (agriculture, recreation, industry, fishing and drinking) on these lakes. The investigation is focused on Lake Iseo, which has shown a significant deterioration of water quality conditions since the seventies, and on Lake Garda, the largest Italian lake where EO data have been widely used for many purposes and applications (Giardino et al., 2014). Available ENVISAT-MERIS (2002-2012) and Landsat-8-OLI (2013-on going) imagery has been exploited to produce chlorophyll-a (chl-a) concentration maps, while Landsat-8-TIRS imagery has been used for estimating lake surface temperatures. MERIS images were processed through a neural network (namely the C2R processor, Doerffer et al., 2007), to correct the atmospheric effects and to retrieve water constituents concentration in optically complex deep waters. With regard to L8's images, some atmospheric correctors (e.g. ACOLITE and 6SV) were tested and validated to indentify, for each of the two lakes, the more accurate

  14. Empirical models of monthly and annual surface albedo in managed boreal forests of Norway

    Science.gov (United States)

    Bright, Ryan M.; Astrup, Rasmus; Strømman, Anders H.

    2013-04-01

    As forest management activities play an increasingly important role in climate change mitigation strategies of Nordic regions such as Norway, Sweden, and Finland -- the need for a more comprehensive understanding of the types and magnitude of biogeophysical climate effects and their various tradeoffs with the global carbon cycle becomes essential to avoid implementation of sub-optimal policy. Forest harvest in these regions reduces the albedo "masking effect" and impacts Earth's radiation budget in opposing ways to that of concomitant carbon cycle perturbations; thus, policies based solely on biogeochemical considerations in these regions risk being counterproductive. There is therefore a need to better understand how human disturbances (i.e., forest management activities) affect important biophysical factors like surface albedo. An 11-year remotely sensed surface albedo dataset coupled with stand-level forest management data for a variety of stands in Norway's most productive logging region are used to develop regression models describing temporal changes in monthly and annual forest albedo following clear-cut harvest disturbance events. Datasets are grouped by dominant tree species and site indices (productivity), and two alternate multiple regression models are developed and tested following a potential plus modifier approach. This resulted in an annual albedo model with statistically significant parameters that explains a large proportion of the observed variation, requiring as few as two predictor variables: i) average stand age - a canopy modifier predictor of albedo, and ii) stand elevation - a local climate predictor of a forest's potential albedo. The same model structure is used to derive monthly albedo models, with models for winter months generally found superior to summer models, and conifer models generally outperforming deciduous. We demonstrate how these statistical models can be applied to routine forest inventory data to predict the albedo

  15. Projecting biodiversity and wood production in future forest landscapes: 15 key modeling considerations.

    Science.gov (United States)

    Felton, Adam; Ranius, Thomas; Roberge, Jean-Michel; Öhman, Karin; Lämås, Tomas; Hynynen, Jari; Juutinen, Artti; Mönkkönen, Mikko; Nilsson, Urban; Lundmark, Tomas; Nordin, Annika

    2017-07-15

    A variety of modeling approaches can be used to project the future development of forest systems, and help to assess the implications of different management alternatives for biodiversity and ecosystem services. This diversity of approaches does however present both an opportunity and an obstacle for those trying to decide which modeling technique to apply, and interpreting the management implications of model output. Furthermore, the breadth of issues relevant to addressing key questions related to forest ecology, conservation biology, silviculture, economics, requires insights stemming from a number of distinct scientific disciplines. As forest planners, conservation ecologists, ecological economists and silviculturalists, experienced with modeling trade-offs and synergies between biodiversity and wood biomass production, we identified fifteen key considerations relevant to assessing the pros and cons of alternative modeling approaches. Specifically we identified key considerations linked to study question formulation, modeling forest dynamics, forest processes, study landscapes, spatial and temporal aspects, and the key response metrics - biodiversity and wood biomass production, as well as dealing with trade-offs and uncertainties. We also provide illustrative examples from the modeling literature stemming from the key considerations assessed. We use our findings to reiterate the need for explicitly addressing and conveying the limitations and uncertainties of any modeling approach taken, and the need for interdisciplinary research efforts when addressing the conservation of biodiversity and sustainable use of environmental resources. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Approaches to modeling landscape-scale drought-induced forest mortality

    Science.gov (United States)

    Gustafson, Eric J.; Shinneman, Douglas

    2015-01-01

    Drought stress is an important cause of tree mortality in forests, and drought-induced disturbance events are projected to become more common in the future due to climate change. Landscape Disturbance and Succession Models (LDSM) are becoming widely used to project climate change impacts on forests, including potential interactions with natural and anthropogenic disturbances, and to explore the efficacy of alternative management actions to mitigate negative consequences of global changes on forests and ecosystem services. Recent studies incorporating drought-mortality effects into LDSMs have projected significant potential changes in forest composition and carbon storage, largely due to differential impacts of drought on tree species and interactions with other disturbance agents. In this chapter, we review how drought affects forest ecosystems and the different ways drought effects have been modeled (both spatially and aspatially) in the past. Building on those efforts, we describe several approaches to modeling drought effects in LDSMs, discuss advantages and shortcomings of each, and include two case studies for illustration. The first approach features the use of empirically derived relationships between measures of drought and the loss of tree biomass to drought-induced mortality. The second uses deterministic rules of species mortality for given drought events to project changes in species composition and forest distribution. A third approach is more mechanistic, simulating growth reductions and death caused by water stress. Because modeling of drought effects in LDSMs is still in its infancy, and because drought is expected to play an increasingly important role in forest health, further development of modeling drought-forest dynamics is urgently needed.

  17. Modeling light use efficiency in a subtropical mangrove forest equipped with CO2 eddy covariance

    Directory of Open Access Journals (Sweden)

    J. G. Barr

    2013-03-01

    Full Text Available Despite the importance of mangrove ecosystems in the global carbon budget, the relationships between environmental drivers and carbon dynamics in these forests remain poorly understood. This limited understanding is partly a result of the challenges associated with in situ flux studies. Tower-based CO2 eddy covariance (EC systems are installed in only a few mangrove forests worldwide, and the longest EC record from the Florida Everglades contains less than 9 years of observations. A primary goal of the present study was to develop a methodology to estimate canopy-scale photosynthetic light use efficiency in this forest. These tower-based observations represent a basis for associating CO2 fluxes with canopy light use properties, and thus provide the means for utilizing satellite-based reflectance data for larger scale investigations. We present a model for mangrove canopy light use efficiency utilizing the enhanced green vegetation index (EVI derived from the Moderate Resolution Imaging Spectroradiometer (MODIS that is capable of predicting changes in mangrove forest CO2 fluxes caused by a hurricane disturbance and changes in regional environmental conditions, including temperature and salinity. Model parameters are solved for in a Bayesian framework. The model structure requires estimates of ecosystem respiration (RE, and we present the first ever tower-based estimates of mangrove forest RE derived from nighttime CO2 fluxes. Our investigation is also the first to show the effects of salinity on mangrove forest CO2 uptake, which declines 5% per each 10 parts per thousand (ppt increase in salinity. Light use efficiency in this forest declines with increasing daily photosynthetic active radiation, which is an important departure from the assumption of constant light use efficiency typically applied in satellite-driven models. The model developed here provides a framework for estimating CO2 uptake by these forests from reflectance data and

  18. Modeling light use efficiency in a subtropical mangrove forest equipped with CO2 eddy covariance

    Science.gov (United States)

    Barr, J.G.; Engel, V.; Fuentes, J.D.; Fuller, D.O.; Kwon, H.

    2013-01-01

    Despite the importance of mangrove ecosystems in the global carbon budget, the relationships between environmental drivers and carbon dynamics in these forests remain poorly understood. This limited understanding is partly a result of the challenges associated with in situ flux studies. Tower-based CO2 eddy covariance (EC) systems are installed in only a few mangrove forests worldwide, and the longest EC record from the Florida Everglades contains less than 9 years of observations. A primary goal of the present study was to develop a methodology to estimate canopy-scale photosynthetic light use efficiency in this forest. These tower-based observations represent a basis for associating CO2 fluxes with canopy light use properties, and thus provide the means for utilizing satellite-based reflectance data for larger scale investigations. We present a model for mangrove canopy light use efficiency utilizing the enhanced green vegetation index (EVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) that is capable of predicting changes in mangrove forest CO2 fluxes caused by a hurricane disturbance and changes in regional environmental conditions, including temperature and salinity. Model parameters are solved for in a Bayesian framework. The model structure requires estimates of ecosystem respiration (RE), and we present the first ever tower-based estimates of mangrove forest RE derived from nighttime CO2 fluxes. Our investigation is also the first to show the effects of salinity on mangrove forest CO2 uptake, which declines 5% per each 10 parts per thousand (ppt) increase in salinity. Light use efficiency in this forest declines with increasing daily photosynthetic active radiation, which is an important departure from the assumption of constant light use efficiency typically applied in satellite-driven models. The model developed here provides a framework for estimating CO2 uptake by these forests from reflectance data and information about

  19. Improving snow cover mapping in forests through the use of a canopy reflectance model

    International Nuclear Information System (INIS)

    Klein, A.G.; Hall, D.K.; Riggs, G.A.

    1998-01-01

    MODIS, the moderate resolution imaging spectro radiometer, will be launched in 1998 as part of the first earth observing system (EOS) platform. Global maps of land surface properties, including snow cover, will be created from MODIS imagery. The MODIS snow-cover mapping algorithm that will be used to produce daily maps of global snow cover extent at 500 m resolution is currently under development. With the exception of cloud cover, the largest limitation to producing a global daily snow cover product using MODIS is the presence of a forest canopy. A Landsat Thematic Mapper (TM) time-series of the southern Boreal Ecosystem–Atmosphere Study (BOREAS) study area in Prince Albert National Park, Saskatchewan, was used to evaluate the performance of the current MODIS snow-cover mapping algorithm in varying forest types. A snow reflectance model was used in conjunction with a canopy reflectance model (GeoSAIL) to model the reflectance of a snow-covered forest stand. Using these coupled models, the effects of varying forest type, canopy density, snow grain size and solar illumination geometry on the performance of the MODIS snow-cover mapping algorithm were investigated. Using both the TM images and the reflectance models, two changes to the current MODIS snow-cover mapping algorithm are proposed that will improve the algorithm's classification accuracy in forested areas. The improvements include using the normalized difference snow index and normalized difference vegetation index in combination to discriminate better between snow-covered and snow-free forests. A minimum albedo threshold of 10% in the visible wavelengths is also proposed. This will prevent dense forests with very low visible albedos from being classified incorrectly as snow. These two changes increase the amount of snow mapped in forests on snow-covered TM scenes, and decrease the area incorrectly identified as snow on non-snow-covered TM scenes. (author)

  20. Modelling the potential role of forest thinning in maintaining water supplies under a changing climate across the conterminous United States

    Science.gov (United States)

    Ge Sun; Peter V. Caldwell; Steven G. McNulty

    2015-01-01

    The goal of this study was to test the sensitivity of water yield to forest thinning and other forest management/disturbances and climate across the conterminous United States (CONUS). Leaf area index (LAI) was selected as a key parameter linking changes in forest ecosystem structure and functions. We used the Water Supply Stress Index model to examine water yield...

  1. Measuring and modeling carbon stock change estimates for US forests and uncertainties from apparent inter-annual variability

    Science.gov (United States)

    James E. Smith; Linda S. Heath

    2015-01-01

    Our approach is based on a collection of models that convert or augment the USDA Forest Inventory and Analysis program survey data to estimate all forest carbon component stocks, including live and standing dead tree aboveground and belowground biomass, forest floor (litter), down deadwood, and soil organic carbon, for each inventory plot. The data, which include...

  2. [Estimation of transition probability in diameter grade transition model of forest population].

    Science.gov (United States)

    Qu, Zhilin; Hu, Haiqing

    2006-12-01

    Based on the theories of statistical analysis and differential equation, two methods were given for estimating the transition probability in the diameter grade transition model of forest population. The first method was used for the estimation when two groups of observation data were given and it was no necessary to consider the environmental factors of forest stand, while the second one was used for that when the environmental factors were known and there was no need of the observation data. The results of case studies showed that both of the two methods had the characteristics of easy operation and high practicability, and the importance of theoretical guidance and practical application in forest management.

  3. Improving city forests through assessment, modelling and monitoring

    Science.gov (United States)

    D.J. Nowak

    2018-01-01

    Urban and peri-urban forests produce numerous benefits for society. These include moderating the climate; reducing energy use in buildings; sequestering atmospheric carbon dioxide; improving air and water quality; mitigating rainfall run-off and flooding; providing an aesthetic environment and recreational opportunities; enhancing human health and social well-being;...

  4. Predictive models of forest logging residues of Triplochiton ...

    African Journals Online (AJOL)

    In this study, biomass yield residue was quantified and equations developed for Triplochiton scleroxylon, in secondary forests, Ondo State, Nigeria. Plotless sampling technique was used for the study. A total of 31 Triplochiton scleroxylon were randomly selected. Tree identification and detailed growing stock of outside bark ...

  5. Modeling wildfire regimes in forest landscapes: abstracting a complex reality

    Science.gov (United States)

    Donald McKenzie; Ajith H. Perera

    2015-01-01

    Fire is a natural disturbance that is nearly ubiquitous in terrestrial ecosystems. The capacity to burn exists virtually wherever vegetation grows. In some forested landscapes, fi re is a principal driver of rapid ecosystem change, resetting succession ( McKenzie et al. 1996a ) and changing wildlife habitat (Cushman et al. 2011 ), hydrology ( Feikema et al. 2013 ),...

  6. Forest evapotranspiration: measurements and modeling at multiple scales

    Science.gov (United States)

    Ge Sun; J-C. Domec; Devendra Amatya

    2016-01-01

    Compared with traditional engineering hydrology, forest hydrology has a relatively long history of studying the effects of vegetation in regulating streamflow through evapotranspiration (Hewlett, 1982; Swank and Crossley, 1988; Andreassian, 2004; Brown et al., 2005; Amatya et al., 2011, 2015, 2016; Sun et al., 2011b; Vose et al., 2011). It is estimated that more than...

  7. Review of methods for modelling forest fire risk and hazard

    African Journals Online (AJOL)

    user

    monitoring methods because ofits repetitive andconsistent coverage over large areas of land (Martin et al., 1999). .... situations however, precipitation does not follow this rule. A similar use of elevation factor for forest fire estimation .... point in the formulation of an emergency plan. In carrying out the risk assessment it will be ...

  8. Total phosphorus reference condition for subalpine lakes: a comparison among traditional methods and a new process-based watershed approach.

    Science.gov (United States)

    Salerno, Franco; Viviano, Gaetano; Carraro, Elisa; Manfredi, Emanuela Chiara; Lami, Andrea; Musazzi, Simona; Marchetto, Aldo; Guyennon, Nicolas; Tartari, Gianni; Copetti, Diego

    2014-12-01

    Different methods for estimating the total phosphorus (TP) reference conditions of lakes have rarely been compared. This work tests the uncertainty and accuracy of the most frequently used approaches (Morpho-edaphic index -MEI-, export coefficient, diatoms and pigment-inferred TP models) for 35 subalpine lakes. Furthermore, we propose a new process-based watershed approach that was tested on a subalpine environment and consists of combining a space for time substitution with a space for space substitution. The possible presence of uncontaminated or less contaminated environments inside or next to the watershed can be exploited by training a hydrological transport watershed model according to the uncontaminated conditions and then applying the calibration to the entire watershed, which reconstructs a natural or semi-natural TP load scenario. We found that the root mean square error (RMSE) for the MEI is 4 μg L(-1). However, its application is limited for lakes that present with an alkalinity ≤1 meq L(-1). For lakes with a higher alkalinity, we observed a loss of predictive capability that results from the lower solubility of phosphorus under conditions of high calcium content. The export coefficient model was applied with a mean export coefficient and presents similar prediction capabilities as the MEI. The chlorophyll-inferred TP model shows a higher uncertainty (RMSE = 8 μg L(-1)); however, it produced fewer underestimations and overestimations. With regards to the diatom-inferred TP model, we are only able to evaluate an uncertainty of 5 μg L(-1) at the European level. Finally, the proposed process-based watershed approach adequately predicted the reference condition of the selected lake and had an uncertainty lower than the other methods (2 μg L(-1)). We conclude by revealing the potential and limitations of this approach in the field of ecological lake modelling more and more attracted by TP pristine load inputs in studies on the effects of

  9. Testing woody fuel consumption models for application in Australian southern eucalypt forest fires

    Science.gov (United States)

    J.J. Hollis; S. Matthews; Roger Ottmar; S.J. Prichard; S. Slijepcevic; N.D. Burrows; B. Ward; K.G. Tolhurst; W.R. Anderson; J S. Gould

    2010-01-01

    Five models for the consumption of coarse woody debris or woody fuels with a diameter larger than 0.6 cm were assessed for application in Australian southern eucalypt forest fires including: CONSUME models for (1) activity fuels, (2) natural western woody and (3) natural southern woody fuels, (4) the BURNUP model and (5) the recommendation by the Australian National...

  10. A practical approach for comparing management strategies in complex forest ecosystems using meta-modelling toolkits

    Science.gov (United States)

    Andrew Fall; B. Sturtevant; M.-J. Fortin; M. Papaik; F. Doyon; D. Morgan; K. Berninger; C. Messier

    2010-01-01

    The complexity and multi-scaled nature of forests poses significant challenges to understanding and management. Models can provide useful insights into process and their interactions, and implications of alternative management options. Most models, particularly scientific models, focus on a relatively small set of processes and are designed to operate within a...

  11. Modelling the migration and accumulation of radionuclides in forest ecosystems. Report of the Forest Working Group of BIOMASS Theme 3

    International Nuclear Information System (INIS)

    2002-08-01

    The IAEA Programme on BIOsphere Modelling and ASSessment (BIOMASS) was launched in Vienna in October 1996. The programme was concerned with developing and improving capabilities to predict the transfer of radionuclides in the environment. The programme had three themes: Theme 1: Radioactive Waste Disposal. The objective was to develop the concept of a standard or reference biosphere for application to the assessment of the long-term safety of repositories for radioactive waste. Under the general heading of 'Reference Biospheres', six Task Groups were established: Task Group 1: Principles for the Definition of Critical and Other Exposure Groups. Task Group 2: Principles for the Application of Data to Assessment Models. Task Group 3: Consideration of Alternative Assessment Contexts. Task Group 4: Biosphere System Identification and Justification. Task Group 5: Biosphere System Descriptions. Task Group 6: Model Development. Theme 2: Environmental Releases. BIOMASS provided an international forum for activities aimed at increasing the confidence in methods and models for the assessment of radiation exposure related to environmental releases. Two Working Groups addressed issues concerned with the reconstruction of radiation doses received by people from past releases of radionuclides to the environment and the evaluation of the efficacy of remedial measures. Theme 3: Biosphere Processes. The aim of this Theme was to improve capabilities for modelling the transfer of radionuclides in particular parts of the biosphere identified as being of potential radiological significance and where there were gaps in modelling approaches. This topic was explored using a range of methods including reviews of the literature, model inter-comparison exercises and, where possible, model testing against independent sources of data. Three Working Groups were established to examine the modelling of: (1) long-term tritium dispersion in the environment; (2) radionuclide uptake by fruits; and (3

  12. Use of fire spread and hydrology models to target forest management on a municipal watershed

    Science.gov (United States)

    Anurag Srivastava; William J. Elliot; Joan Wu

    2015-01-01

    A small town relies on a forested watershed for its water supply. The forest is at risk for a wildfire. To reduce this risk, some of the watershed will be thinned followed by a prescribed burn. This paper reports on a study to evaluate the impact of such watershed disturbances on water yield. To target management activities, a fire spread model was applied to the...

  13. Evapotranspiration and heat fluxes over a small forest - a study using modelling and measurements

    DEFF Research Database (Denmark)

    Sogachev, Andrey; Dellwik, Ebba; Boegh, Eva

    2013-01-01

    are very often used for calibration of forest parameters or model constants, further use of these parameters without a proper interpretation in mesoscale or global circulation models can result in serious bias of estimates of modelled evapotranspiration or heat fluxes from the given area. In the present...... work, we apply the atmospheric boundary layer (ABL) model SCADIS with enhanced turbulence closure including buoyancy for investigation of the spatial distribution of latent and sensible heat vertical fluxes over patchy forested terrain in Denmark during selected days in the summer period. The approach...

  14. Earthworms, arthropods and plant litter decomposition in aspen (Populus tremuloides) and lodgepole pine(Pinus contorta) forests in Colorado, USA

    Science.gov (United States)

    Grizelle Gonzalez; Timothy R. Seastedt; Zugeily Donato

    2003-01-01

    We compared the abundance and community composition of earthworms, soil macroarthropods, and litter microarthropods to test faunal effects on plant litter decomposition rates in two forests in the subalpine in Colorado, USA. Litterbags containing recently senesced litter of Populus tremuloides (aspen) and Pinus contorta (lodgepole pine) were placed in aspen and pine...

  15. Modelling black spruce primary production and carbon allocation in the Quebec boreal forest

    Science.gov (United States)

    Gennaretti, Fabio; Guiot, Joel; Berninger, Frank; Boucher, Etienne; Gea-Izquierdo, Guillermo

    2017-04-01

    Boreal ecosystems are crucial carbon stores that must be urgently quantified and preserved. Their future evolution is extremely important for the global carbon budget. Here, we will show the progresses achieved with the MAIDEN forest ecophysiological model in simulating carbon fluxes of black spruce (Picea mariana (Mill.) B.S.P.) forests, the most representative ecosystem of the North American boreal biome. Starting from daily minimum-maximum air temperature, precipitation and CO2 atmospheric concentration, MAIDEN models the phenological (5 phenological phases are simulated each year) and meteorological controls on gross primary production (GPP) and carbon allocation to stem. The model is being calibrated on eddy covariance and tree-ring data. We will discuss the model's performance and the modifications introduced in MAIDEN to adapt the model to temperature sensitive forests of the boreal region.

  16. Understanding the radar backscattering from flooded and nonflooded Amazonian forests: results from canopy backscatter modeling

    International Nuclear Information System (INIS)

    Wang, Y.; Hess, L.L.; Filoso, S.; Melack, J.M.

    1995-01-01

    To understand the potential of using multiwavelength imaging radars to detect flooding in Amazonian floodplain forests, we simulated the radar backscatter from a floodplain forest with a flooded or nonflooded ground condition at C-, L-, and P-bands. Field measurements of forest structure in the Anavilhanas archipelago of the Negro River, Brazil, were used as inputs to the model. Given the same wavelength or incidence angle, the ratio of backscatter from the flooded forest to that from the nonflooded forest was higher at HH polarization than at VV polarization. Given the same wavelength or polarization, the ratio was larger at small incidence angles than at large incidence angles. Given the same polarization or incidence angle, the ratio was larger at a long wavelength than at a short wavelength. As the surface soil moisture underneath the nonflooded forest increased from 10% to 50% of volumetric moisture, the flooded/nonflooded backscatter ratio decreased; the decreases were small at C- and L-band but large at P-band. When the leaf size was comparable to or larger than the wavelength of C-band, the leaf area index (LAI) had a large effect on the simulated C-band (not L-band or P-band) backscatter from the flooded and nonflooded forests. (author)

  17. Transpiration of A Mixed Forest Stand: Field Measurements and Model Estimations

    Science.gov (United States)

    Oltchev, A.; Cermak, J.; Nadezhdina, N.; Tatarinov, F.; Gravenhorst, G.

    Transpiration of a mixed spruce-aspen-birch forest stand at the southern part of the Valday Hills in Russia was determined using sap flow measurements and SVAT mod- els. The measurements showed a significant variability of transpiration rates between different species and different trees. Under non-limited soil water conditions broadleaf trees transpired about 10-20% more than spruces trees. Deficit of available water in the upper soil layers had a more pronounced influence on water uptake of spruce than of deciduous tree species due to the shallow spruce root system. Under surplus wa- ter in the upper soil layers the transpiration rates were slightly suppressed both for spruce and for broadleaf tree species. Two one-dimensional multi-layer SVAT mod- els were applied to describe energy and water exchanges between mixed forest stand and the atmosphere. A more simplified MLOD-SVAT model uses averaged biophys- ical properties of different tree species. Estimation of forest water uptake in a more sophisticated EWE-MF model is based on separate description of water uptakes for individual tree species. Comparisons of modelling and measuring results show that under non-limited soil water conditions both modelling approaches allow to describe in a representative way the water uptake and transpiration rates. Under limited soil water conditions more sophisticated model could deduce more representatively the effect of different tree species on forest transpiration. Application of more simplified MLOD-SVAT model can result in an overestimation of daily total forest transpiration up to 50%.

  18. A Novel Modelling Approach for Predicting Forest Growth and Yield under Climate Change.

    Science.gov (United States)

    Ashraf, M Irfan; Meng, Fan-Rui; Bourque, Charles P-A; MacLean, David A

    2015-01-01

    Global climate is changing due to increasing anthropogenic emissions of greenhouse gases. Forest managers need growth and yield models that can be used to predict future forest dynamics during the transition period of present-day forests under a changing climatic regime. In this study, we developed a forest growth and yield model that can be used to predict individual-tree growth under current and projected future climatic conditions. The model was constructed by integrating historical tree growth records with predictions from an ecological process-based model using neural networks. The new model predicts basal area (BA) and volume growth for individual trees in pure or mixed species forests. For model development, tree-growth data under current climatic conditions were obtained using over 3000 permanent sample plots from the Province of Nova Scotia, Canada. Data to reflect tree growth under a changing climatic regime were projected with JABOWA-3 (an ecological process-based model). Model validation with designated data produced model efficiencies of 0.82 and 0.89 in predicting individual-tree BA and volume growth. Model efficiency is a relative index of model performance, where 1 indicates an ideal fit, while values lower than zero means the predictions are no better than the average of the observations. Overall mean prediction error (BIAS) of basal area and volume growth predictions was nominal (i.e., for BA: -0.0177 cm(2) 5-year(-1) and volume: 0.0008 m(3) 5-year(-1)). Model variability described by root mean squared error (RMSE) in basal area prediction was 40.53 cm(2) 5-year(-1) and 0.0393 m(3) 5-year(-1) in volume prediction. The new modelling approach has potential to reduce uncertainties in growth and yield predictions under different climate change scenarios. This novel approach provides an avenue for forest managers to generate required information for the management of forests in transitional periods of climate change. Artificial intelligence technology

  19. A Novel Modelling Approach for Predicting Forest Growth and Yield under Climate Change.

    Directory of Open Access Journals (Sweden)

    M Irfan Ashraf

    Full Text Available Global climate is changing due to increasing anthropogenic emissions of greenhouse gases. Forest managers need growth and yield models that can be used to predict future forest dynamics during the transition period of present-day forests under a changing climatic regime. In this study, we developed a forest growth and yield model that can be used to predict individual-tree growth under current and projected future climatic conditions. The model was constructed by integrating historical tree growth records with predictions from an ecological process-based model using neural networks. The new model predicts basal area (BA and volume growth for individual trees in pure or mixed species forests. For model development, tree-growth data under current climatic conditions were obtained using over 3000 permanent sample plots from the Province of Nova Scotia, Canada. Data to reflect tree growth under a changing climatic regime were projected with JABOWA-3 (an ecological process-based model. Model validation with designated data produced model efficiencies of 0.82 and 0.89 in predicting individual-tree BA and volume growth. Model efficiency is a relative index of model performance, where 1 indicates an ideal fit, while values lower than zero means the predictions are no better than the average of the observations. Overall mean prediction error (BIAS of basal area and volume growth predictions was nominal (i.e., for BA: -0.0177 cm(2 5-year(-1 and volume: 0.0008 m(3 5-year(-1. Model variability described by root mean squared error (RMSE in basal area prediction was 40.53 cm(2 5-year(-1 and 0.0393 m(3 5-year(-1 in volume prediction. The new modelling approach has potential to reduce uncertainties in growth and yield predictions under different climate change scenarios. This novel approach provides an avenue for forest managers to generate required information for the management of forests in transitional periods of climate change. Artificial intelligence

  20. Allometric Models for Estimating Tree Volume and Aboveground Biomass in Lowland Forests of Tanzania

    Directory of Open Access Journals (Sweden)

    Wilson Ancelm Mugasha

    2016-01-01

    Full Text Available Models to assist management of lowland forests in Tanzania are in most cases lacking. Using a sample of 60 trees which were destructively harvested from both dry and wet lowland forests of Dindili in Morogoro Region (30 trees and Rondo in Lindi Region (30 trees, respectively, this study developed site specific and general models for estimating total tree volume and aboveground biomass. Specifically the study developed (i height-diameter (ht-dbh models for trees found in the two sites, (ii total, merchantable, and branches volume models, and (iii total and sectional aboveground biomass models of trees found in the two study sites. The findings show that site specific ht-dbh model appears to be suitable in estimating tree height since the tree allometry was found to differ significantly between studied forests. The developed general volume models yielded unbiased mean prediction error and hence can adequately be applied to estimate tree volume in dry and wet lowland forests in Tanzania. General aboveground biomass model appears to yield biased estimates; hence, it is not suitable when accurate results are required. In this case, site specific biomass allometric models are recommended. Biomass allometric models which include basic wood density are highly recommended for improved estimates accuracy when such information is available.

  1. Absorber Model: the Halo-like model for the Lyman-α forest

    Science.gov (United States)

    Iršič, Vid; McQuinn, Matthew

    2018-04-01

    We present a semi-analytic model for the Lyman-α forest that is inspired by the Halo Model. This model is built on the absorption line decomposition of the forest. Flux correlations are decomposed into those within each absorption line (the 1-absorber term) and those between separate lines (the 2-absorber term), treating the lines as biased tracers of the underlying matter fluctuations. While the nonlinear exponential mapping between optical depth and flux requires an infinite series of moments to calculate any statistic, we show that this series can be re-summed (truncating at the desired order in the linear matter overdensity). We focus on the z=2–3 line-of-sight power spectrum. Our model finds that 1-absorber term dominates the power on all scales, with most of its contribution coming from H I columns of 1014–1015 cm‑2, while the smaller 2-absorber contribution comes from lower columns that trace overdensities of a few. The prominence of the 1-absorber correlations indicates that the line-of-sight power spectrum is shaped principally by the lines' number densities and their absorption profiles, with correlations between lines contributing to a lesser extent. We present intuitive formulae for the effective optical depth as well as the large-scale limits of 1-absorber and 2-absorber terms, which simplify to integrals over the H I column density distribution with different equivalent-width weightings. With minimalist models for the bias of absorption systems and their peculiar velocity broadening, our model predicts values for the density bias and velocity gradient bias that are consistent with those found in simulations.

  2. A stochastic Forest Fire Model for future land cover scenarios assessment

    Directory of Open Access Journals (Sweden)

    M. D'Andrea

    2010-10-01

    Full Text Available Land cover is affected by many factors including economic development, climate and natural disturbances such as wildfires. The ability to evaluate how fire regimes may alter future vegetation, and how future vegetation may alter fire regimes, would assist forest managers in planning management actions to be carried out in the face of anticipated socio-economic and climatic change. In this paper, we present a method for calibrating a cellular automata wildfire regime simulation model with actual data on land cover and wildfire size-frequency. The method is based on the observation that many forest fire regimes, in different forest types and regions, exhibit power law frequency-area distributions. The standard Drossel-Schwabl cellular automata Forest Fire Model (DS-FFM produces simulations which reproduce this observed pattern. However, the standard model is simplistic in that it considers land cover to be binary – each cell either contains a tree or it is empty – and the model overestimates the frequency of large fires relative to actual landscapes. Our new model, the Modified Forest Fire Model (MFFM, addresses this limitation by incorporating information on actual land use and differentiating among various types of flammable vegetation. The MFFM simulation model was tested on forest types with Mediterranean and sub-tropical fire regimes. The results showed that the MFFM was able to reproduce structural fire regime parameters for these two regions. Further, the model was used to forecast future land cover. Future research will extend this model to refine the forecasts of future land cover and fire regime scenarios under climate, land use and socio-economic change.

  3. Coupling a distributed hydrological model with detailed forest structural information for large-scale global change impact assessment

    Science.gov (United States)

    Eisner, Stephanie; Huang, Shaochun; Majasalmi, Titta; Bright, Ryan; Astrup, Rasmus; Beldring, Stein

    2017-04-01

    Forests are recognized for their decisive effect on landscape water balance with structural forest characteristics as stand density or species composition determining energy partitioning and dominant flow paths. However, spatial and temporal variability in forest structure is often poorly represented in hydrological modeling frameworks, in particular in regional to large scale hydrological modeling and impact analysis. As a common practice, prescribed land cover classes (including different generic forest types) are linked to parameter values derived from literature, or parameters are determined by calibration. While national forest inventory (NFI) data provide comprehensive, detailed information on hydrologically relevant forest characteristics, their potential to inform hydrological simulation over larger spatial domains is rarely exploited. In this study we present a modeling framework that couples the distributed hydrological model HBV with forest structural information derived from the Norwegian NFI and multi-source remote sensing data. The modeling framework, set up for the entire of continental Norway at 1 km spatial resolution, is explicitly designed to study the combined and isolated impacts of climate change, forest management and land use change on hydrological fluxes. We use a forest classification system based on forest structure rather than biomes which allows to implicitly account for impacts of forest management on forest structural attributes. In the hydrological model, different forest classes are represented by three parameters: leaf area index (LAI), mean tree height and surface albedo. Seasonal cycles of LAI and surface albedo are dynamically simulated to make the framework applicable under climate change conditions. Based on a hindcast for the pilot regions Nord-Trøndelag and Sør-Trøndelag, we show how forest management has affected regional hydrological fluxes during the second half of the 20th century as contrasted to climate variability.

  4. An individual-based growth and competition model for coastal redwood forest restoration

    Science.gov (United States)

    van Mantgem, Phillip J.; Das, Adrian J.

    2014-01-01

    Thinning treatments to accelerate coastal redwood forest stand development are in wide application, but managers have yet to identify prescriptions that might best promote Sequoia sempervirens (Lamb. ex D. Don) Endl. (redwood) growth. The creation of successful thinning prescriptions would be aided by identifying the underlying mechanisms governing how individual tree growth responds to competitive environments in coastal redwood forests. We created a spatially explicit individual-based model of tree competition and growth parameterized using surveys of upland redwood forests at Redwood National Park, California. We modeled competition for overstory trees (stems ≥ 20 cm stem diameter at breast height, 1.37 m (dbh)) as growth reductions arising from sizes, distances, and species identity of competitor trees. Our model explained up to half of the variation in individual tree growth, suggesting that neighborhood crowding is an important determinant of growth in this forest type. We used our model to simulate the effects of novel thinning prescriptions (e.g., 40% stand basal area removal) for redwood forest restoration, concluding that these treatments could lead to substantial growth releases, particularly for S. sempervirens. The results of this study, along with continued improvements to our model, will help to determine spacing and species composition that best encourage growth.

  5. Validation of modelled forest biomass in Germany using BETHY/DLR

    Directory of Open Access Journals (Sweden)

    M. Tum

    2011-11-01

    Full Text Available We present a new approach to the validation of modelled forest Net Primary Productivity (NPP, using empirical data on the mean annual increment, or MAI, in above-ground forest stock. The soil-vegetation-atmosphere-transfer model BETHY/DLR is used, with a particular focus on a detailed parameterization of photosynthesis, to estimate the NPP of forest areas in Germany, driven by remote sensing data from VEGETATION, meteorological data from the European Centre for Medium-Range Weather Forecasts (ECMWF, and additional tree coverage information from the MODIS Vegetation Continuous Field (VCF. The output of BETHY/DLR, Gross Primary Productivity (GPP, is converted to NPP by subtracting the cumulative plant maintenance and growth respiration, and then validated against MAI data that was calculated from German forestry inventories. Validation is conducted for 2000 and 2001 by converting modelled NPP to stem volume at a regional level. Our analysis shows that the presented method fills an important gap in methods for validating modelled NPP against empirically derived data. In addition, we examine theoretical energy potentials calculated from the modelled and validated NPP, assuming sustainable forest management and using species-specific tree heating values. Such estimated forest biomass energy potentials play an important role in the sustainable energy debate.

  6. The derivation of sub-canopy surface terrain models of coastal forests using synthetic aperture radar

    Science.gov (United States)

    Imhoff, M. L.; Gesch, D. B.

    1988-01-01

    Radar data acquired by the Shuttle Imaging Radar-B mission covering a portion of the Mouths of the Ganges forests were used to create a terrain model for use in determining tidal flow and eventual nutrient transport from the forest to the marine habitat. Results show that good digital topographic terrain models of wet coastal forests can be generated using multiple sets of L-band SAR and ancillary tide elevation data. The dominance of the interaction phenomenon in the radar backscatter of flooded forests can be used to create sub-canopy inundation maps which when merged with tide surface data can be used to generate reasonable topographic models. Ideally models could be improved by using multiple sets of data at a constant incidence angle over the total tide range. The optimal angle for the SAR depends upon the characteristics of the forest. The range of 46 to 57 deg seems applicable to the 12.5 m tall closed canopy in this example. Such models can be an extremely valuable tool for studying and mapping the mangal ecosystem.

  7. A spatial model for assessing forest fire danger in the Sierra Madre Oriental Mountains, Mexico

    Directory of Open Access Journals (Sweden)

    Carlos Alfonso Muñoz Robles

    2012-02-01

    Full Text Available The aim of this study was to develop a model for assessing forest fire danger in a temperate forest located in the state of Nuevo León, Mexico. A spatial multicriteria analysis was conducted in order to integrate and evaluate in a Geographic Information System those variables that influence fire danger levels. The structure of the fire danger index included three components. The forest fuels component, generated through the inventory of dead surface fuels loads; the weather index, that was built trough the analysis of maximum monthly mean temperature and total monthly precipitation. The last component of the fire danger index was calculated by assessing social and economic features. The three components were integrated into a decision rule, and monthly maps were created to show the location of forest fire danger vulnerability.

  8. Improving simulated spatial distribution of productivity and biomass in Amazon forests using the ACME land model

    Science.gov (United States)

    Yang, X.; Thornton, P. E.; Ricciuto, D. M.; Shi, X.; Xu, M.; Hoffman, F. M.; Norby, R. J.

    2017-12-01

    Tropical forests play a crucial role in the global carbon cycle, accounting for one third of the global NPP and containing about 25% of global vegetation biomass and soil carbon. This is particularly true for tropical forests in the Amazon region, as it comprises approximately 50% of the world's tropical forests. It is therefore important for us to understand and represent the processes that determine the fluxes and storage of carbon in these forests. In this study, we show that the implementation of phosphorus (P) cycle and P limitation in the ACME Land Model (ALM) improves simulated spatial pattern of NPP. The P-enabled ALM is able to capture the west-to-east gradient of productivity, consistent with field observations. We also show that by improving the representation of mortality processes, ALM is able to reproduce the observed spatial pattern of above ground biomass across the Amazon region.

  9. Bark flammability as a fire-response trait for subalpine trees.

    Science.gov (United States)

    Frejaville, Thibaut; Curt, Thomas; Carcaillet, Christopher

    2013-01-01

    Relationships between the flammability properties of a given plant and its chances of survival after a fire still remain unknown. We hypothesize that the bark flammability of a tree reduces the potential for tree survival following surface fires, and that if tree resistance to fire is provided by a thick insulating bark, the latter must be few flammable. We test, on subalpine tree species, the relationship between the flammability of bark and its insulating ability, identifies the biological traits that determine bark flammability, and assesses their relative susceptibility to surface fires from their bark properties. The experimental set of burning properties was analyzed by Principal Component Analysis to assess the bark flammability. Bark insulating ability was expressed by the critical time to cambium kill computed from bark thickness. Log-linear regressions indicated that bark flammability varies with the bark thickness and the density of wood under bark and that the most flammable barks have poor insulating ability. Susceptibility to surface fires increases from gymnosperm to angiosperm subalpine trees. The co-dominant subalpine species Larix decidua (Mill.) and Pinus cembra (L.) exhibit large differences in both flammability and insulating ability of the bark that should partly explain their contrasted responses to fires in the past.

  10. Bark flammability as a fire-response trait for subalpine trees

    Directory of Open Access Journals (Sweden)

    Thibaut eFrejaville

    2013-11-01

    Full Text Available Relationships between the flammability properties of a given plant and its chances of survival after a fire still remain unknown. We hypothesize that the bark flammability of a tree reduces the potential for tree survival following surface fires, and that if tree resistance to fire is provided by a thick insulating bark, the latter must be few flammable. We tests, on subalpine tree species, the relationship between the flammability of bark and its insulating ability, identifies the biological traits that determine bark flammability, and assesses their relative susceptibility to surface fires from their bark properties. The experimental set of burning properties was analyzed by Principal Component Analysis to assess the bark flammability. Bark insulating ability was expressed by the critical time to cambium kill computed from bark thickness. Log-linear regressions indicated that bark flammability varies with the bark thickness and the density of wood under bark and that the most flammable barks have poor insulating ability. Susceptibility to surface fires increases from gymnosperm to angiosperm subalpine trees. The co-dominant subalpine species Larix decidua (Mill. and Pinus cembra (L. exhibit large differences in both flammability and insulating ability of the bark that should partly explain their contrasted responses to fires in the past.

  11. The agony of choice: different empirical mortality models lead to sharply different future forest dynamics.

    Science.gov (United States)

    Bircher, Nicolas; Cailleret, Maxime; Bugmann, Harald

    2015-07-01

    Dynamic models are pivotal for projecting forest dynamics in a changing climate, from the local to the global scale. They encapsulate the processes of tree population dynamics with varying resolution. Yet, almost invariably, tree mortality is modeled based on simple, theoretical assumptions that lack a physiological and/or empirical basis. Although this has been widely criticized and a growing number of empirically derived alternatives are available, they have not been tested systematically in models of forest dynamics. We implemented an inventory-based and a tree-ring-based mortality routine in the forest gap model ForClim v3.0. We combined these routines with a stochastic and a deterministic approach for the determination of tree status (alive vs. dead). We tested the four new model versions for two Norway spruce forests in the Swiss Alps, one of which was managed (inventory time series spanning 72 years) and the other was unmanaged (41 years). Furthermore, we ran long-term simulations (-400 years) into the future under three climate scenarios to test model behavior under changing environmental conditions. The tests against inventory data showed an excellent match of simulated basal area and stem numbers at the managed site and a fair agreement at the unmanaged site for three of the four empirical mortality models, thus rendering the choice of one particular model difficult. However, long-term simulations under current climate revealed very different behavior of the mortality models in terms of simulated changes of basal area and stem numbers, both in timing and magnitude, thus indicating high sensitivity of simulated forest dynamics to assumptions on tree mortality. Our results underpin the potential of using empirical mortality routines in forest gap models. However, further tests are needed that span other climatic conditions and mixed forests. Short-term simulations to benchmark model behavior against empirical data are insufficient; long-term tests are

  12. LiDAR based prediction of forest biomass using hierarchical models with spatially varying coefficients

    Science.gov (United States)

    Chad Babcock; Andrew O. Finley; John B. Bradford; Randy Kolka; Richard Birdsey; Michael G. Ryan

    2015-01-01

    Many studies and production inventory systems have shown the utility of coupling covariates derived from Light Detection and Ranging (LiDAR) data with forest variables measured on georeferenced inventory plots through regression models. The objective of this study was to propose and assess the use of a Bayesian hierarchical modeling framework that accommodates both...

  13. Comparing i-Tree modeled ozone deposition with field measurements in a periurban Mediterranean forest

    Science.gov (United States)

    A. Morani; D. Nowak; S. Hirabayashi; G. Guidolotti; M. Medori; V. Muzzini; S. Fares; G. Scarascia Mugnozza; C. Calfapietra

    2014-01-01

    Ozone flux estimates from the i-Tree model were compared with ozone flux measurements using the Eddy Covariance technique in a periurban Mediterranean forest near Rome (Castelporziano). For the first time i-Tree model outputs were compared with field measurements in relation to dry deposition estimates. Results showed generally a...

  14. Simulating ozone dry deposition at a boreal forest with a multi-layer canopy deposition model

    NARCIS (Netherlands)

    Zhou, Putian; Ganzeveld, Laurens; Rannik, Ullar; Zhou, Luxi; Gierens, Rosa; Taipale, Ditte; Mammarella, Ivan; Boy, Michael

    2017-01-01

    A multi-layer ozone (O3) dry deposition model has been implemented into SOSAA (a model to Simulate the concentrations of Organic vapours, Sulphuric Acid and Aerosols) to improve the representation of O3 concentration and flux within and above the forest canopy in the planetary boundary layer. We

  15. A note on estimating urban roof runoff with a forest evaporation model

    NARCIS (Netherlands)

    Gash, J.H.C.; Rosier, P.T.W.; Ragab, R.

    2008-01-01

    A model developed for estimating the evaporation of rainfall intercepted by forest canopies is applied to estimate measurements of the average runoff from the roofs of six houses made in a previous study of hydrological processes in an urban environment. The model is applied using values of the mean

  16. Adapting forest management to climate change using bioclimate models with topographic drivers

    Science.gov (United States)

    Gerald E. Rehfeldt; James J. Worrall; Suzanne B. Marchetti; Nicholas L. Crookston

    2015-01-01

    Bioclimate models incorporating topographic predictors as surrogates for microclimate effects are developed for Populus tremuloides and Picea engelmannii to provide the fine-grained specificity to local terrain required for adapting management of three Colorado (USA) national forests (1.28 million ha) and their periphery to climate change. Models were built with the...

  17. Application of two forest succession models at sites in Northeast Germany

    International Nuclear Information System (INIS)

    Lasch, P.; Lindner, M.

    1995-06-01

    In order to simulate potential impacts of climate change on forests, two succession models were applied to sites in the Northeast German lowlands. The models, which had been developed for Alpine (FORECE) and Boreal (FORSKA) forests differ from each other in the way they represent tree growth processes and the impact of environmental factors on establishment and growth. Both models were adjusted and compared with each other at sites that are situated along an ecological gradient from maritime to subcontinental climate. These sites are extending the former environmental space of model application towards water limited conditions, which under a predicted climatic change may have increasing importance for European forests. First results showed that FORECE was unrealistically sensitive to changes in soil moisture. On the other hand, FORSKA generally simulated very low biomasses. Since the structure of FORSKA seemed to be better suited for the simulation of changing environmental conditions, this model was chosen for further model development, applications and sensitivity analyses. Among other changes, establishment rates were increased and some environmental response factors were analysed. The function of account for resource depletion was modified. After the modifications for Central European conditions were made, there was a decrease in performance for the Boreal site. Both simulated total biomasses and species composition had changed. We conclude, that with currently available models, realistic forest dynamics within different climatic zones of Europe cannot be simulated without more substantial model modifications. (orig.)

  18. Modelling recovery from soil acidification in European forests under climate change

    NARCIS (Netherlands)

    Reinds, G.J.; Posch, M.; Leemans, R.

    2009-01-01

    A simple soil acidification model was applied to evaluate the effects of sulphur and nitrogen emission reductions on the recovery of acidified European forest soils. In addition we included the effects of climate change on soil solution chemistry, by modelling temperature effects on soil chemical

  19. Spatial models reveal the microclimatic buffering capacity of old-growth forests

    Science.gov (United States)

    Sarah J. K. Frey; Adam S. Hadley; Sherri L. Johnson; Mark Schulze; Julia A. Jones; Matthew. G. Betts

    2016-01-01

    Climate change is predicted to cause widespread declines in biodiversity, but these predictions are derived from coarse-resolution climate models applied at global scales. Such models lack the capacity to incorporate microclimate variability, which is critical to biodiversity microrefugia. In forested montane regions, microclimate is thought to be influenced by...

  20. Development of a GIS interface for WEPP Model application to Great Lakes forested watersheds

    Science.gov (United States)

    J. R. Frankenberger; S. Dun; D. C. Flanagan; J. Q. Wu; W. J. Elliot

    2011-01-01

    This presentation will highlight efforts on development of a new online WEPP GIS interface, targeted toward application in forested regions bordering the Great Lakes. The key components and algorithms of the online GIS system will be outlined. The general procedures used to provide input to the WEPP model and to display model output will be demonstrated.

  1. Modelling surface conductance and transpiration of an oak forest in The Netherlands

    NARCIS (Netherlands)

    Ogink-Hendriks, M.J.

    1995-01-01

    The surface conductance of an oak forest was modelled as a non-linear function of solar radiation, temperature, specific humidity deficit, soil moisture deficit and leaf area index. Two Jarvis-Stewart type models were used, differing only in the formulation of the specific humidity function. Both

  2. A comparison of empirical and modeled nitrogen critical loads for Mediterranean forests and shrublands in California

    Science.gov (United States)

    M.E. Fenn; H.-D. Nagel; I. Koseva; J. Aherne; S.E. Jovan; L.H. Geiser; A. Schlutow; T. Scheuschner; A. Bytnerowicz; B.S. Gimeno; F. Yuan; S.A. Watmough; E.B. Allen; R.F. Johnson; T. Meixner

    2014-01-01

    Nitrogen (N) deposition is impacting a number of ecosystem types in California. Critical loads (CLs) for N deposition determined for mixed conifer forests and chaparral/oak woodlands in the Sierra Nevada Mountains of California and the San Bernardino Mountains in southern California using empirical and various modelling approaches were compared. Models used included...

  3. Forest-fire model as a supercritical dynamic model in financial systems

    Science.gov (United States)

    Lee, Deokjae; Kim, Jae-Young; Lee, Jeho; Kahng, B.

    2015-02-01

    Recently large-scale cascading failures in complex systems have garnered substantial attention. Such extreme events have been treated as an integral part of self-organized criticality (SOC). Recent empirical work has suggested that some extreme events systematically deviate from the SOC paradigm, requiring a different theoretical framework. We shed additional theoretical light on this possibility by studying financial crisis. We build our model of financial crisis on the well-known forest fire model in scale-free networks. Our analysis shows a nontrivial scaling feature indicating supercritical behavior, which is independent of system size. Extreme events in the supercritical state result from bursting of a fat bubble, seeds of which are sown by a protracted period of a benign financial environment with few shocks. Our findings suggest that policymakers can control the magnitude of financial meltdowns by keeping the economy operating within reasonable duration of a benign environment.

  4. A high performance finite element model for wind farm modeling in forested areas

    Science.gov (United States)

    Owen, Herbert; Avila, Matias; Folch, Arnau; Cosculluela, Luis; Prieto, Luis

    2015-04-01

    Wind energy has grown significantly during the past decade and is expected to continue growing in the fight against climate change. In the search for new land where the impact of the wind turbines is small several wind farms are currently being installed in forested areas. In order to optimize the distribution of the wind turbines within the wind farm the Reynolds Averaged Navier Stokes equations are solved over the domain of interest using either commercial or in house codes. The existence of a canopy alters the Atmospheric Boundary Layer wind profile close to the ground. Therefore in order to obtain a more accurate representation of the flow in forested areas modification to both the Navier Stokes and turbulence variables equations need to be introduced. Several existing canopy models have been tested in an academic problem showing that the one proposed by Sogachev et. al gives the best results. This model has been implemented in an in house CFD solver named Alya. It is a high performance unstructured finite element code that has been designed from scratch to be able to run in the world's biggest supercomputers. Its scalabililty has recently been tested up to 100000 processors in both American and European supercomputers. During the past three years the code has been tuned and tested for wind energy problems. Recent efforts have focused on the canopy model following industry needs. In this work we shall benchmark our results in a wind farm that is currently being designed by Scottish Power and Iberdrola in Scotland. This is a very interesting real case with extensive experimental data from five different masts with anemometers at several heights. It is used to benchmark both the wind profiles and the speed up obtained between different masts. Sixteen different wind directions are simulated. The numerical model provides very satisfactory results for both the masts that are affected by the canopy and those that are not influenced by it.

  5. [Eco-value level classification model of forest ecosystem based on modified projection pursuit technique].

    Science.gov (United States)

    Wu, Chengzhen; Hong, Wei; Hong, Tao

    2006-03-01

    To optimize the projection function and direction of projection pursuit technique, predigest its realization process, and overcome the shortcomings in long time calculation and in the difficulty of optimizing projection direction and computer programming, this paper presented a modified simplex method (MSM), and based on it, brought forward the eco-value level classification model (EVLCM) of forest ecosystem, which could integrate the multidimensional classification index into one-dimensional projection value, with high projection value denoting high ecosystem services value. Examples of forest ecosystem could be reasonably classified by the new model according to their projection value, suggesting that EVLCM driven directly by samples data of forest ecosystem was simple and feasible, applicable, and maneuverable. The calculating time and value of projection function were 34% and 143% of those with the traditional projection pursuit technique, respectively. This model could be applied extensively to classify and estimate all kinds of non-linear and multidimensional data in ecology, biology, and regional sustainable development.

  6. Spatio-temporal analysis of forest modeling in Mexico

    Directory of Open Access Journals (Sweden)

    Saira Y. Martínez-Santiago

    2017-01-01

    Full Text Available Hay consenso de que las acciones antropogénicas están degradando los ecosistemas a un ritmo alarmante. La modelación y las nuevas tecnologías, como las tecnologías de la información y de la comunicación ( TIC, se utilizan en modo creciente para tomar decisiones sobre el manejo y la conservación de los recursos naturales. En este trabajo se analizaron la evolución temporal y la distribución espacial de la producción científica en modelación forestal en México. De 1980 a 2015, 454 autores participaron en la publicación de 259 artículos en 37 revistas (84 % mexicanas, de las cuales 28 están indizadas en el Journal Citation Reports (JCR. Los trabajos sobre manejo forestal han sido los más relevantes, aunque tienen una importancia relativa a la baja, mientras que los de servicios ambientales y distribución potencial van ganando importancia. Los autores pertenecen a 89 instituciones, de las cuales 65 % son mexicanas. Durante el periodo analizado, el número de autores (y las colaboraciones y publicaciones incrementaron 12 y nueve veces, respectivamente. Estos incrementos coinciden con la evolución de las políticas normativas y el establecimiento y apoyo del Sistema Nacional de Investigadores. Las colaboraciones en la red actual de modelación forestal aún tienen gran potencial de crecimiento.

  7. Model Development For Wireless Propagation In Forested Environments

    Science.gov (United States)

    2015-09-01

    country without going mentally insane . xviii THIS PAGE INTENTIONALLY LEFT BLANK 1 I. INTRODUCTION A. COMPLEXITY OF A FORESTED...Distance, d (m) 5 10 15 20 25 30 35 R ec ei ve d P ow er , P r ( dB m ) -70 -60 -50 -40 -30 -20 -10 0 Received Power - Free Space Received Power - Foliage...power outside and inside the foliage block for horizontally polarized antennas at 1.2 m. Distance, d (m) 5 10 15 20 25 30 35 R ec ei ve d P ow er

  8. Modeling the Carbon Implications of Ecologically Based Forest Management

    Science.gov (United States)

    2015-08-20

    Fule, P.Z., Moore, M.M., Hart, S.C., Kolb , T.E., Mast, J.N., Sackett, S.S., Wagner, M.R., 1997. Restoring ecosystem health in ponderosa pine forests of...Botanical Society 129, 289-297. Dore, S., Kolb , T.E., Montes-Helu, M., Sullivan, B.W., Winslow, W.D., Hart, S.C., Kaye, J.P., Koch, G.W...Dore, S., M. Montes-Helu, S.C. Hart, B.A. Hungate, G.W. Koch, J.B. Moon, A.J. Finkral, T.E. Kolb . 2012. Recovery of ponderosa pine ecosystem carbon and

  9. Modeling the Carbon Implications of Ecologically-Based Forest Management

    Science.gov (United States)

    2015-08-01

    Fule, P.Z., Moore, M.M., Hart, S.C., Kolb , T.E., Mast, J.N., Sackett, S.S., Wagner, M.R., 1997. Restoring ecosystem health in ponderosa pine forests of...Botanical Society 129, 289-297. Dore, S., Kolb , T.E., Montes-Helu, M., Sullivan, B.W., Winslow, W.D., Hart, S.C., Kaye, J.P., Koch, G.W...Dore, S., M. Montes-Helu, S.C. Hart, B.A. Hungate, G.W. Koch, J.B. Moon, A.J. Finkral, T.E. Kolb . 2012. Recovery of ponderosa pine ecosystem carbon and

  10. Assessing the protection function of Alpine forest ecosystems using BGC modelling theory

    Science.gov (United States)

    Pötzelsberger, E.; Hasenauer, H.; Petritsch, R.; Pietsch, S. A.

    2009-04-01

    The purpose of this study was to assess the protection function of forests in Alpine areas by modelling the flux dynamics (water, carbon, nutrients) within a watershed as they may depend on the vegetation pattern and forest management impacts. The application case for this study was the catchment Schmittenbach, located in the province of Salzburg. Data available covered the hydrology (rainfall measurements from 1981 to 1998 and runoff measurements at the river Schmittenbach from 1981 to 2005), vegetation dynamics (currently 69% forest, predominantly Norway Spruce). The method of simulating the forest growth and water outflow was validated. For simulations of the key ecosystem processes (e.g. photosynthesis, carbon and nitrogen allocation in the different plant parts, litter fall, mineralisation, tree water uptake, transpiration, rainfall interception, evaporation, snow accumulation and snow melt, outflow of spare water) the biogeochemical ecosystem model Biome-BGC was applied. Relevant model extensions were the tree species specific parameter sets and the improved thinning regime. The model is sensitive to site characteristics and needs daily weather data and information on the atmospheric composition, which makes it sensitive to higher CO2-levels and climate change. For model validation 53 plots were selected covering the full range of site quality and stand age. Tree volume and soil was measured and compared with the respective model results. The outflow for the watershed was predicted by combining the simulated forest-outflow (derived from plot-outflow) with the outflow from the non-forest area (calculated with a fixed outflow/rainfall coefficient (OC)). The analysis of production and water related model outputs indicated that mechanistic modelling can be used as a tool to assess the performance of Alpine protection forests. The Water Use Efficiency (WUE), the ratio of Net primary production (NPP) and Transpiration, was found the highest for juvenile stands (

  11. Semantic World Modelling and Data Management in a 4d Forest Simulation and Information System

    Science.gov (United States)

    Roßmann, J.; Hoppen, M.; Bücken, A.

    2013-08-01

    Various types of 3D simulation applications benefit from realistic forest models. They range from flight simulators for entertainment to harvester simulators for training and tree growth simulations for research and planning. Our 4D forest simulation and information system integrates the necessary methods for data extraction, modelling and management. Using modern methods of semantic world modelling, tree data can efficiently be extracted from remote sensing data. The derived forest models contain position, height, crown volume, type and diameter of each tree. This data is modelled using GML-based data models to assure compatibility and exchangeability. A flexible approach for database synchronization is used to manage the data and provide caching, persistence, a central communication hub for change distribution, and a versioning mechanism. Combining various simulation techniques and data versioning, the 4D forest simulation and information system can provide applications with "both directions" of the fourth dimension. Our paper outlines the current state, new developments, and integration of tree extraction, data modelling, and data management. It also shows several applications realized with the system.

  12. Quantifying Forest Ecosystem Services Tradeoff—Coupled Ecological and Economic Models

    Science.gov (United States)

    Haff, P. K.; Ling, P. Y.

    2015-12-01

    Quantification of the effect of carbon-related forestland management activities on ecosystem services is difficult, because knowledge about the dynamics of coupled social-ecological systems is lacking. Different forestland management activities, such as various amount, timing, and methods of harvesting, and natural disturbances events, such as wind and fires, create shocks and uncertainties to the forest carbon dynamics. A spatially explicit model, Landis-ii, was used to model the forest succession for different harvest management scenarios at the Grandfather District, North Carolina. In addition to harvest, the model takes into account of the impact of natural disturbances, such as fire and insects, and species competition. The result shows the storage of carbon in standing biomass and in wood product for each species for each scenario. In this study, optimization is used to analyze the maximum profit and the number of tree species that each forest landowner can gain at different prices of carbon, roundwood, and interest rates for different harvest management scenarios. Time series of roundwood production of different types were estimated using remote sensing data. Econometric analysis is done to understand the possible interaction and relations between the production of different types of roundwood and roundwood prices, which can indicate the possible planting scheme that a forest owner may make. This study quantifies the tradeoffs between carbon sequestration, roundwood production, and forest species diversity not only from an economic perspective, but also takes into account of the forest succession mechanism in a species-diverse region. The resulting economic impact on the forest landowners is likely to influence their future planting decision, which in turn, will influence the species composition and future revenue of the landowners.

  13. Moderate forest disturbance as a stringent test for gap and big-leaf models

    Science.gov (United States)

    Bond-Lamberty, B.; Fisk, J. P.; Holm, J. A.; Bailey, V.; Bohrer, G.; Gough, C. M.

    2015-01-01

    Disturbance-induced tree mortality is a key factor regulating the carbon balance of a forest, but tree mortality and its subsequent effects are poorly represented processes in terrestrial ecosystem models. It is thus unclear whether models can robustly simulate moderate (non-catastrophic) disturbances, which tend to increase biological and structural complexity and are increasingly common in aging US forests. We tested whether three forest ecosystem models - Biome-BGC (BioGeochemical Cycles), a classic big-leaf model, and the ZELIG and ED (Ecosystem Demography) gap-oriented models - could reproduce the resilience to moderate disturbance observed in an experimentally manipulated forest (the Forest Accelerated Succession Experiment in northern Michigan, USA, in which 38% of canopy dominants were stem girdled and compared to control plots). Each model was parameterized, spun up, and disturbed following similar protocols and run for 5 years post-disturbance. The models replicated observed declines in aboveground biomass well. Biome-BGC captured the timing and rebound of observed leaf area index (LAI), while ZELIG and ED correctly estimated the magnitude of LAI decline. None of the models fully captured the observed post-disturbance C fluxes, in particular gross primary production or net primary production (NPP). Biome-BGC NPP was correctly resilient but for the wrong reasons, and could not match the absolute observational values. ZELIG and ED, in contrast, exhibited large, unobserved drops in NPP and net ecosystem production. The biological mechanisms proposed to explain the observed rapid resilience of the C cycle are typically not incorporated by these or other models. It is thus an open question whether most ecosystem models will simulate correctly the gradual and less extensive tree mortality characteristic of moderate disturbances.

  14. Application of terrestrial laser scanner for analyzing snowpack distribution in Pyrenean subalpine and forested sites

    OpenAIRE

    Revuelto Benedí, Jesús

    2015-01-01

    La nieve juega un papel protagonista en numerosos procesos ambientales, hidrológicos y económicos en zonas de montaña. Por otro lado, el manto de nieve presenta una elevadísima variabilidad espacial y temporal, acentuada por la heterogeneidad del terreno típica de las zonas alpinas. Los procesos que controlan dicha variabilidad no son aún del todo comprendidos, y por ello han sido el principal objeto de estudio del trabajo desarrollado en esta Tesis. Multitud de procesos geomorfológicos, ...

  15. Soil fauna and plant litter decomposition in tropical and subalpine forests

    Science.gov (United States)

    G. Gonzalez; T.R. Seastedt

    2001-01-01

    The decomposition of plant residues is influenced by their chemical composition, the physical-chemical environment, and the decomposer organisms. Most studies interested in latitudinal gradients of decomposition have focused on substrate quality and climate effects on decomposition, and have excluded explicit recognition of the soil organisms involved in the process....

  16. Utilizing Forest Inventory and Analysis Data, Remote Sensing, and Ecosystem Models for National Forest System Carbon Assessments

    Science.gov (United States)

    Alexa J. Dugan; Richard A. Birdsey; Sean P. Healey; Christopher Woodall; Fangmin Zhang; Jing M. Chen; Alexander Hernandez; James B. McCarter

    2015-01-01

    Forested lands, representing the largest terrestrial carbon sink in the United States, offset 16% of total U.S. carbon dioxide emissions through carbon sequestration. Meanwhile, this carbon sink is threatened by deforestation, climate change and natural disturbances. As a result, U.S. Forest Service policies require that National Forests assess baseline carbon stocks...

  17. Detecting forest structure and biomass with C-band multipolarization radar - Physical model and field tests

    Science.gov (United States)

    Westman, Walter E.; Paris, Jack F.

    1987-01-01

    The ability of C-band radar (4.75 GHz) to discriminate features of forest structure, including biomass, is tested using a truck-mounted scatterometer for field tests on a 1.5-3.0 m pygmy forest of cypress (Cupressus pygmaea) and pine (Pinus contorta ssp, Bolanderi) near Mendocino, CA. In all, 31 structural variables of the forest are quantified at seven sites. Also measured was the backscatter from a life-sized physical model of the pygmy forest, composed of nine wooden trees with 'leafy branches' of sponge-wrapped dowels. This model enabled independent testing of the effects of stem, branch, and leafy branch biomass, branch angle, and moisture content on radar backscatter. Field results suggested that surface area of leaves played a greater role in leaf scattering properties than leaf biomass per se. Tree leaf area index was strongly correlated with vertically polarized power backscatter (r = 0.94; P less than 0.01). Field results suggested that the scattering role of leaf water is enhanced as leaf surface area per unit leaf mass increases; i.e., as the moist scattering surfaces become more dispersed. Fog condensate caused a measurable rise in forest backscatter, both from surface and internal rises in water content. Tree branch mass per unit area was highly correlated with cross-polarized backscatter in the field (r = 0.93; P less than 0.01), a result also seen in the physical model.

  18. Complementary models of tree species-soil relationships in old-growth temperate forests

    Science.gov (United States)

    Cross, Alison; Perakis, Steven S.

    2011-01-01

    Ecosystem level studies identify plant soil feed backs as important controls on soil nutrient availability,particularly for nitrogen and phosphorus. Although site and species specific studies of tree species soil relationships are relatively common,comparatively fewer studies consider multiple coexisting speciesin old-growth forests across a range of sites that vary underlying soil fertility. We characterized patterns in forest floor and mineral soil nutrients associated with four common tree species across eight undisturbed old-growth forests in Oregon, USA, and used two complementary conceptual models to assess tree species soil relationships. Plant soil feedbacks that could reinforce sitelevel differences in nutrient availability were assessed using the context dependent relationships model, where by relative species based differences in each soil nutrient divergedorconvergedas nutrient status changed across sites. Tree species soil relationships that did not reflect strong feedbacks were evaluated using a site independent relationships model, where by forest floor and surface mineral soil nutrient tools differed consistently by tree species across sites,without variation in deeper mineral soils. We found that theorganically cycled elements carbon, nitrogen, and phosphorus exhibited context-dependent differences among species in both forest floor and mineral soil, and most of ten followed adivergence model,where by species differences were greatest at high-nutrient sites. These patterns are consistent with the oryemphasizing biotic control of these elements through plant soil feedback mechanisms. Site independent species differences were strongest for pool so if the weather able cations calcium, magnesium, potassium,as well as phosphorus, in mineral soils. Site independent species differences in forest floor nutrients we reattributable too nespecies that displayed significant greater forest floor mass accumulation. Our finding confirmed that site-independent and

  19. Increased Drought Impacts on Temperate Rainforests from Southern South America: Results of a Process-Based, Dynamic Forest Model

    OpenAIRE

    Gutiérrez, Alvaro G.; Armesto, Juan J.; Díaz, M. Francisca; Huth, Andreas

    2014-01-01

    Increased droughts due to regional shifts in temperature and rainfall regimes are likely to affect forests in temperate regions in the coming decades. To assess their consequences for forest dynamics, we need predictive tools that couple hydrologic processes, soil moisture dynamics and plant productivity. Here, we developed and tested a dynamic forest model that predicts the hydrologic balance of North Patagonian rainforests on Chiloé Island, in temperate South America (42°S). The model incor...

  20. Combining Multi-Source Remotely Sensed Data and a Process-Based Model for Forest Aboveground Biomass Updating.

    Science.gov (United States)

    Lu, Xiaoman; Zheng, Guang; Miller, Colton; Alvarado, Ernesto

    2017-09-08

    Monitoring and understanding the spatio-temporal variations of forest aboveground biomass (AGB) is a key basis to quantitatively assess the carbon sequestration capacity of a forest ecosystem. To map and update forest AGB in the Greater Khingan Mountains (GKM) of China, this work proposes a physical-based approach. Based on the baseline forest AGB from Landsat Enhanced Thematic Mapper Plus (ETM+) images in 2008, we dynamically updated the annual forest AGB from 2009 to 2012 by adding the annual AGB increment (ABI) obtained from the simulated daily and annual net primary productivity (NPP) using the Boreal Ecosystem Productivity Simulator (BEPS) model. The 2012 result was validated by both field- and aerial laser scanning (ALS)-based AGBs. The predicted forest AGB for 2012 estimated from the process-based model can explain 31% ( n = 35, p BEPS-based AGB tended to underestimate/overestimate the AGB for dense/sparse forests. Generally, our results showed that the remotely sensed forest AGB estimates could serve as the initial carbon pool to parameterize the process-based model for NPP simulation, and the combination of the baseline forest AGB and BEPS model could effectively update the spatiotemporal distribution of forest AGB.

  1. UAV-based photogrammetric 3D modelling and surveillance of forest wildfires

    OpenAIRE

    Krukowski, Artur; Vogiatzaki, Emmanouela

    2017-01-01

    This article presents work performed in the frame of ongoing FP7-SEC project “Advanced Forest Fire Fighting” in areas of UAV-based 3D surveillance and 3D area mapping. Photogrammetric 3D scanning and modelling from H2020-SCAN4RECO project have been used for producing high-resolution models of incident areas from multi-spectral imaging. We also present a proprietary embedded sensor system used for detection of fire ignitions in the forest using near-infrared based scanner with weight and form ...

  2. Braking effect of climate and topography on global change-induced upslope forest expansion.

    Science.gov (United States)

    Alatalo, Juha M; Ferrarini, Alessandro

    2017-03-01

    Forests are expected to expand into alpine areas due to global climate change. It has recently been shown that temperature alone cannot realistically explain this process and that upslope tree advance in a warmer scenario may depend on the availability of sites with adequate geomorphic/topographic characteristics. Here, we show that, besides topography (slope and aspect), climate itself can produce a braking effect on the upslope advance of subalpine forests and that tree limit is influenced by non-linear and non-monotonic contributions of the climate variables which act upon treeline upslope advance with varying relative strengths. Our results suggest that global climate change impact on the upslope advance of subalpine forests should be interpreted in a more complex way where climate can both speed up and slow down the process depending on complex patterns of contribution from each climate and non-climate variable.

  3. Selection bias in species distribution models: An econometric approach on forest trees based on structural modeling

    Science.gov (United States)

    Martin-StPaul, N. K.; Ay, J. S.; Guillemot, J.; Doyen, L.; Leadley, P.

    2014-12-01

    Species distribution models (SDMs) are widely used to study and predict the outcome of global changes on species. In human dominated ecosystems the presence of a given species is the result of both its ecological suitability and human footprint on nature such as land use choices. Land use choices may thus be responsible for a selection bias in the presence/absence data used in SDM calibration. We present a structural modelling approach (i.e. based on structural equation modelling) that accounts for this selection bias. The new structural species distribution model (SSDM) estimates simultaneously land use choices and species responses to bioclimatic variables. A land use equation based on an econometric model of landowner choices was joined to an equation of species response to bioclimatic variables. SSDM allows the residuals of both equations to be dependent, taking into account the possibility of shared omitted variables and measurement errors. We provide a general description of the statistical theory and a set of applications on forest trees over France using databases of climate and forest inventory at different spatial resolution (from 2km to 8km). We also compared the outputs of the SSDM with outputs of a classical SDM (i.e. Biomod ensemble modelling) in terms of bioclimatic response curves and potential distributions under current climate and climate change scenarios. The shapes of the bioclimatic response curves and the modelled species distribution maps differed markedly between SSDM and classical SDMs, with contrasted patterns according to species and spatial resolutions. The magnitude and directions of these differences were dependent on the correlations between the errors from both equations and were highest for higher spatial resolutions. A first conclusion is that the use of classical SDMs can potentially lead to strong miss-estimation of the actual and future probability of presence modelled. Beyond this selection bias, the SSDM we propose represents

  4. The numerical model for parametric studies of forest haul roads pavements

    Directory of Open Access Journals (Sweden)

    Lenka Ševelová

    2010-01-01

    Full Text Available Forest roads pavement structures are considered to be low volume roads. These roads serve as a mean of transport of wood and people. Besides they are currently often used for recreational purpose. The construction of the pavements should be suitable for forest transportation irrespective of their low bearing capacity. These pavement structures are very specific for special unbound materials that are used in their construction. To meet the requirements of the pavement designs and simulation analysis the FEM model in the software ANSYS was created.This paper compares two material models used for the description of the behaviour of unbound materials. The first is linear elastic according to Hook theory (H model and the second one is nonlinear plastic model Drucker-Prager (D–P model. ANSYS software has been used to create flexible model based on the parametrers of variable principle. The flexible model is parametric to realize repeated calculations useful for optimization analysis.

  5. Application of a niche-based model for forest cover classification

    Directory of Open Access Journals (Sweden)

    Amici V

    2012-05-01

    Full Text Available In recent years, a surge of interest in biodiversity conservation have led to the development of new approaches to facilitate ecologically-based conservation policies and management plans. In particular, image classification and predictive distribution modeling applied to forest habitats, constitute a crucial issue as forests constitute the most widespread vegetation type and play a key role for ecosystem functioning. Then, the general purpose of this study is to develop a framework that in the absence of large amounts of field data for large areas may allow to select the most appropriate classification. In some cases, a hard division of classes is required, especially as support to environmental policies; despite this it is necessary to take into account problems which derive from a crisp view of ecological entities being mapped, since habitats are expected to be structurally complex and continuously vary within a landscape. In this paper, a niche model (MaxEnt, generally used to estimate species/habitat distribution, has been applied to classify forest cover in a complex Mediterranean area and to estimate the probability distribution of four forest types, producing continuous maps of forest cover. The use of the obtained models as validation of model for crisp classifications, highlighted that crisp classification, which is being continuously used in landscape research and planning, is not free from drawbacks as it is showing a high degree of inner variability. The modeling approach followed by this study, taking into account the uncertainty proper of the natural ecosystems and the use of environmental variables in land cover classification, may represent an useful approach to making more efficient and effective field inventories and to developing effective forest conservation policies.

  6. Model-directed sampling in Chernobyl forests: General methodology and 1994 sampling program

    International Nuclear Information System (INIS)

    Radiologically-contaminated forest and natural ecosystems contribute significantly to the human radiation dose in the intermediate (several years) and long (several decades) terms following the radionuclide release. As a result of the Chernobyl nuclear power plant accident in 1986, extensive forested areas in Europe were significantly contaminated with cesium, strontium, plutonium and other radionuclides. This study develops a dynamic model that describes the pathways of radionuclides which undergo complex transfer processes in forests and natural ecosystems. This generic model, FORESTPATH, calculates time-dependent radionuclide concentrations in forest compartments based on the information available on residence half-times. Because of the high complexity, traditional sampling programs often provide only limited and fragmented information for the ecosystem to be modeled. A model-directed sampling program was initiated which implies close feedback between ecosystem sampling and modeling of the radionuclide pathways using the FORESTPATH model. This program is now being applied by an international team of USA, European Union (EU) and Newly Independent States (NIS) members in the Chernobyl Nuclear Power Plant (NPP) Exclusion Zone

  7. Using Count Data and Ordered Models in National Forest Recreation Demand Analysis

    Science.gov (United States)

    Simões, Paula; Barata, Eduardo; Cruz, Luis

    2013-11-01

    This research addresses the need to improve our knowledge on the demand for national forests for recreation and offers an in-depth data analysis supported by the complementary use of count data and ordered models. From a policy-making perspective, while count data models enable the estimation of monetary welfare measures, ordered models allow for the wider use of the database and provide a more flexible analysis of data. The main purpose of this article is to analyse the individual forest recreation demand and to derive a measure of its current use value. To allow a more complete analysis of the forest recreation demand structure the econometric approach supplements the use of count data models with ordered category models using data obtained by means of an on-site survey in the Bussaco National Forest (Portugal). Overall, both models reveal that travel cost and substitute prices are important explanatory variables, visits are a normal good and demographic variables seem to have no influence on demand. In particular, estimated price and income elasticities of demand are quite low. Accordingly, it is possible to argue that travel cost (price) in isolation may be expected to have a low impact on visitation levels.

  8. Modeling the temporal dynamics of nonstructural carbohydrate pools in forest trees

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, Andrew [Northern Arizona Univ., Flagstaff, AZ (United States); Harvard Univ., Cambridge, MA (United States)

    2017-11-09

    Trees store carbohydrates, in the form of sugars and starch, as reserves to be used to power both future growth as well as to support day-to-day metabolic functions. These reserves are particularly important in the context of how trees cope with disturbance and stress—for example, as related to pest outbreaks, wind or ice damage, and extreme climate events. In this project, we measured the size of carbon reserves in forest trees, and determined how quickly these reserves are used and replaced—i.e., their “turnover time”. Our work was conducted at Harvard Forest, a temperate deciduous forest in central Massachusetts. Through field sampling, laboratory-based chemical analyses, and allometric modeling, we scaled these measurements up to whole-tree NSC budgets. We used these data to test and improve computer simulation models of carbon flow through forest ecosystems. Our modeling focused on the mathematical representation of these stored carbon reserves, and we examined the sensitivity of model performance to different model structures. This project contributes to DOE’s goal to improve next-generation models of the earth system, and to understand the impacts of climate change on terrestrial ecosystems.

  9. Element cycling in forest soils - modelling the effects of a changing environment

    Energy Technology Data Exchange (ETDEWEB)

    Walse, C.

    1998-11-01

    Element cycling and nutrient supply in forest ecosystems are of vital importance for short-term productivity and for longer-term land management in terms of nutrient leaching and CO{sub 2} fixation. This thesis includes a series of studies with the objective of modelling some aspects of the effect of acidification and climate change on element cycling and nutrient supply in forest soil. A reconstruction model of atmospheric deposition and nutrient uptake and cycling, MAKEDEP, was developed. An existing model of soil chemistry, SAFE, was analyzed and applied. SAFE+MAKEDEP were then applied in combination with the RAINS model to perform scenario analyses of soil acidification/recovery for six European forest sites. A decomposition model intended to run in conjunction with the SAFE model was developed. Key elements were N, Ca, K, Mg, S and Al. In the decomposition model, only carbon release was included to date.The results show, that understanding the history of soil geochemistry is important for modelling the system and for projecting the future impact of acidification on nutrient supply in forest soils. The applied reconstruction models of acid deposition (MAKEDEP, RAINS) seem to generate reasonable and consistent estimates of historic acid deposition, so that present day conditions can be simulated starting from pre-acidification conditions. From applications of the SAFE model to large-scale forest manipulation experiments, we conclude that the geochemical processes and the degree of detail in process descriptions included in SAFE are adequate to capture the most important aspects of soil solution dynamics of forest soils in northern and central Europe. Therefore, SAFE is appropriate for the simulation of acidification and recovery scenarios for these soils. The precision in model prediction on a more general scale is often limited by factors other than model formulation, such as consistency and representativity of input data. It is shown that the physical

  10. Numerical modeling of watershed-scale radiocesium transport coupled with biogeochemical cycling in forests

    Science.gov (United States)

    Mori, K.; Tada, K.; Tawara, Y.; Tosaka, H.; Ohno, K.; Asami, M.; Kosaka, K.

    2015-12-01

    Since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, intensive monitoring and modeling works on radionuclide transfer in environment have been carried out. Although Cesium (Cs) concentration has been attenuating due to both physical and environmental half-life (i.e., wash-off by water and sediment), the attenuation rate depends clearly on the type of land use and land cover. In the Fukushima case, studying the migration in forest land use is important for predicting the long-term behavior of Cs because most of the contaminated region is covered by forests. Atmospheric fallout is characterized by complicated behavior in biogeochemical cycle in forests which can be described by biotic/abiotic interactions between many components. In developing conceptual and mathematical model on Cs transfer in forest ecosystem, defining the dominant components and their interactions are crucial issues (BIOMASS, 1997-2001). However, the modeling of fate and transport in geosphere after Cs exports from the forest ecosystem is often ignored. An integrated watershed modeling for simulating spatiotemporal redistribution of Cs that includes the entire region from source to mouth and surface to subsurface, has been recently developed. Since the deposited Cs can migrate due to water and sediment movement, the different species (i.e., dissolved and suspended) and their interactions are key issues in the modeling. However, the initial inventory as source-term was simplified to be homogeneous and time-independent, and biogeochemical cycle in forests was not explicitly considered. Consequently, it was difficult to evaluate the regionally-inherent characteristics which differ according to land uses, even if the model was well calibrated. In this study, we combine the different advantages in modeling of forest ecosystem and watershed. This enable to include more realistic Cs deposition and time series of inventory can be forced over the land surface. These processes are integrated

  11. 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

  12. Modeling Forest Biomass and Growth: Coupling Long-Term Inventory and Lidar Data

    Science.gov (United States)

    Babcock, Chad; Finley, Andrew O.; Cook, Bruce D.; Weiskittel, Andrew; Woodall, Christopher W.

    2016-01-01

    Combining spatially-explicit long-term forest inventory and remotely sensed information from Light Detection and Ranging (LiDAR) datasets through statistical models can be a powerful tool for predicting and mapping above-ground biomass (AGB) at a range of geographic scales. We present and examine a novel modeling approach to improve prediction of AGB and estimate AGB growth using LiDAR data. The proposed model accommodates temporal misalignment between field measurements and remotely sensed data-a problem pervasive in such settings-by including multiple time-indexed measurements at plot locations to estimate AGB growth. We pursue a Bayesian modeling framework that allows for appropriately complex parameter associations and uncertainty propagation through to prediction. Specifically, we identify a space-varying coefficients model to predict and map AGB and its associated growth simultaneously. The proposed model is assessed using LiDAR data acquired from NASA Goddard's LiDAR, Hyper-spectral & Thermal imager and field inventory data from the Penobscot Experimental Forest in Bradley, Maine. The proposed model outperformed the time-invariant counterpart models in predictive performance as indicated by a substantial reduction in root mean squared error. The proposed model adequately accounts for temporal misalignment through the estimation of forest AGB growth and accommodates residual spatial dependence. Results from this analysis suggest that future AGB models informed using remotely sensed data, such as LiDAR, may be improved by adapting traditional modeling frameworks to account for temporal misalignment and spatial dependence using random effects.

  13. The possible influence of terracettes on surface hydrology of steep-sloping and subalpine environments

    Science.gov (United States)

    Greenwood, Philip; Kuonen, Samuel; Fister, Wolfgang; Kuhn, Nikolaus

    2015-04-01

    Alpine and mountain slopes represent important pathways that link high altitude grazing areas to meadows and rangelands at lower elevations. Given the often acute gradients associated with such environments, they potentially represent highly efficient runoff conveyance routes that presumably facilitate the downslope movement of runoff and associated material during erosion events. Many such slopes host series of small steps, or `terracettes`. The position of terracette systems, usually juxtaposed across the natural downslope flow-path of acute slopes, lead us to hypothesise that their presence may influence typical hillslope processes by intercepting or capturing surface runoff during its downslope transit. Here we report preliminary results and some tentative conclusions from on-going work to explore this possibility. Google Earth was used to initially identify a ca. 400 m2 area of well-developed terracette system situated on a west-facing slope with gradients ranging from 25-40o (46-84%). A digital elevation model (DEM) of a section of the terracette system was constructed using spatial data taken from a relevant excerpt of a topographic map. The DEM was then queried using a flow accumulation algorithm and the results were displayed in a Geographic Information System (GIS). The output data provided 'proof of concept' that terracettes are able to capture surface runoff. A series of rainfall / runoff simulations was then performed on the same section of terracettes. Results from both components of the investigation indicate that certain sections of a terracette system intercepted surface runoff and acted as preferential flow-pathways during runoff events. By contrast, and despite being subjected to intense rainfall, some sections of the same terracette system did not generate surface runoff. Based on these contrasting findings, we cautiously predict that areas where surface runoff was not generated may actually act as depositional sites, or retention zones, and

  14. EVALUATING THE NOVEL METHODS ON SPECIES DISTRIBUTION MODELING IN COMPLEX FOREST

    Directory of Open Access Journals (Sweden)

    C. H. Tu

    2012-07-01

    Full Text Available The prediction of species distribution has become a focus in ecology. For predicting a result more effectively and accurately, some novel methods have been proposed recently, like support vector machine (SVM and maximum entropy (MAXENT. However, high complexity in the forest, like that in Taiwan, will make the modeling become even harder. In this study, we aim to explore which method is more applicable to species distribution modeling in the complex forest. Castanopsis carlesii (long-leaf chinkapin, LLC, growing widely in Taiwan, was chosen as the target species because its seeds are an important food source for animals. We overlaid the tree samples on the layers of altitude, slope, aspect, terrain position, and vegetation index derived from SOPT-5 images, and developed three models, MAXENT, SVM, and decision tree (DT, to predict the potential habitat of LLCs. We evaluated these models by two sets of independent samples in different site and the effect on the complexity of forest by changing the background sample size (BSZ. In the forest with low complex (small BSZ, the accuracies of SVM (kappa = 0.87 and DT (0.86 models were slightly higher than that of MAXENT (0.84. In the more complex situation (large BSZ, MAXENT kept high kappa value (0.85, whereas SVM (0.61 and DT (0.57 models dropped significantly due to limiting the habitat close to samples. Therefore, MAXENT model was more applicable to predict species’ potential habitat in the complex forest; whereas SVM and DT models would tend to underestimate the potential habitat of LLCs.

  15. Modelling the role of forests on water provision services: a hydro-economic valuation approach

    Science.gov (United States)

    Beguería, S.; Campos, P.

    2015-12-01

    Hydro-economic models that allow integrating the ecological, hydrological, infrastructure, economic and social aspects into a coherent, scientifically- informed framework constitute preferred tools for supporting decision making in the context of integrated water resources management. We present a case study of water regulation and provision services of forests in the Andalusia region of Spain. Our model computes the physical water flows and conducts an economic environmental income and asset valuation of forest surface and underground water yield. Based on available hydrologic and economic data, we develop a comprehensive water account for all the forest lands at the regional scale. This forest water environmental valuation is integrated within a much larger project aiming at providing a robust and easily replicable accounting tool to evaluate yearly the total income and capital of forests, encompassing all measurable sources of private and public incomes (timber and cork production, auto-consumption, recreational activities, biodiversity conservation, carbon sequestration, water production, etc.). We also force our simulation with future socio-economic scenarios to quantify the physical and economic efects of expected trends or simulated public and private policies on future water resources. Only a comprehensive integrated tool may serve as a basis for the development of integrated policies, such as those internationally agreed and recommended for the management of water resources.

  16. Canards and mixed-mode oscillations in a forest pest model

    DEFF Research Database (Denmark)

    Brøns, Morten; Kaasen, Rune

    2010-01-01

    of high pest concentration. For small values of the timescale of the young trees, the model can be reduced to a two-dimensional model. By a geometrical analysis we identify a canard explosion in the reduced model, that is, a change over a narrow parameter interval from outbreak dynamics to small......We consider a three-variable forest pest model, proposed by Rinaldi & Muratori (1992) [Rinaldi, S., Muratori, S., 1992. Limit cycles in slow-fast forest-pest models. Theor. Popul. Biol. 41,26-43]. The model allows relaxation oscillations where long pest-free periods are interspersed with outbreaks...... oscillations around an endemic state. For larger values of the timescale of the young trees the two-dimensional approximation breaks down, and a broader parameter interval with mixed-mode oscillations appear, replacing the simple canard explosion. The analysis only relies on simple and generic properties...

  17. Ecophysiological modeling of photosynthesis and carbon allocation to the tree stem in the boreal forest

    Directory of Open Access Journals (Sweden)

    F. Gennaretti

    2017-11-01

    Full Text Available A better understanding of the coupling between photosynthesis and carbon allocation in the boreal forest, together with its associated environmental factors and mechanistic rules, is crucial to accurately predict boreal forest carbon stocks and fluxes, which are significant components of the global carbon budget. Here, we adapted the MAIDEN ecophysiological forest model to consider important processes for boreal tree species, such as nonlinear acclimation of photosynthesis to temperature changes, canopy development as a function of previous-year climate variables influencing bud formation and the temperature dependence of carbon partition in summer. We tested these modifications in the eastern Canadian taiga using black spruce (Picea mariana (Mill. B.S.P. gross primary production and ring width data. MAIDEN explains 90 % of the observed daily gross primary production variability, 73 % of the annual ring width variability and 20–30 % of its high-frequency component (i.e., when decadal trends are removed. The positive effect on stem growth due to climate warming over the last several decades is well captured by the model. In addition, we illustrate how we improve the model with each introduced model adaptation and compare the model results with those of linear response functions. Our results demonstrate that MAIDEN simulates robust relationships with the most important climate variables (those detected by classical response-function analysis and is a powerful tool for understanding how environmental factors interact with black spruce ecophysiology to influence present-day and future boreal forest carbon fluxes.

  18. Ecophysiological modeling of photosynthesis and carbon allocation to the tree stem in the boreal forest

    Science.gov (United States)

    Gennaretti, Fabio; Gea-Izquierdo, Guillermo; Boucher, Etienne; Berninger, Frank; Arseneault, Dominique; Guiot, Joel

    2017-11-01

    A better understanding of the coupling between photosynthesis and carbon allocation in the boreal forest, together with its associated environmental factors and mechanistic rules, is crucial to accurately predict boreal forest carbon stocks and fluxes, which are significant components of the global carbon budget. Here, we adapted the MAIDEN ecophysiological forest model to consider important processes for boreal tree species, such as nonlinear acclimation of photosynthesis to temperature changes, canopy development as a function of previous-year climate variables influencing bud formation and the temperature dependence of carbon partition in summer. We tested these modifications in the eastern Canadian taiga using black spruce (Picea mariana (Mill.) B.S.P.) gross primary production and ring width data. MAIDEN explains 90 % of the observed daily gross primary production variability, 73 % of the annual ring width variability and 20-30 % of its high-frequency component (i.e., when decadal trends are removed). The positive effect on stem growth due to climate warming over the last several decades is well captured by the model. In addition, we illustrate how we improve the model with each introduced model adaptation and compare the model results with those of linear response functions. Our results demonstrate that MAIDEN simulates robust relationships with the most important climate variables (those detected by classical response-function analysis) and is a powerful tool for understanding how environmental factors interact with black spruce ecophysiology to influence present-day and future boreal forest carbon fluxes.

  19. Bi-criteria evaluation of the MIKE SHE model for a forested watershed on the South Carolina coastal plain

    Science.gov (United States)

    Z. Dai; C. Li; C. Trettin; G. Sun; D. Amatya; H. Li

    2010-01-01

    Hydrological models are important tools for effective management, conservation and restoration of forested wetlands. The objective of this study was to test a distributed hydrological model, MIKE SHE, by using bi-criteria (i.e., two measurable variables, streamflow and water table depth) to describe the hydrological processes in a forested watershed that is...

  20. An innovative computer design for modeling forest landscape change in very large spatial extents with fine resolutions

    Science.gov (United States)

    Jian Yang; Hong S. He; Stephen R. Shifley; Frank R. Thompson; Yangjian. Zhang

    2011-01-01

    Although forest landscape models (FLMs) have benefited greatly from ongoing advances of computer technology and software engineering, computing capacity remains a bottleneck in the design and development of FLMs. Computer memory overhead and run time efficiency are primary limiting factors when applying forest landscape models to simulate large landscapes with fine...

  1. Building generalized tree mass/volume component models for improved estimation of forest stocks and utilization potential

    Science.gov (United States)

    David W. MacFarlane

    2015-01-01

    Accurately assessing forest biomass potential is contingent upon having accurate tree biomass models to translate data from forest inventories. Building generality into these models is especially important when they are to be applied over large spatial domains, such as regional, national and international scales. Here, new, generalized whole-tree mass / volume...

  2. LANDIS 4.0 users guide. LANDIS: a spatially explicit model of forest landscape disturbance, management, and succession

    Science.gov (United States)

    Hong S. He; Wei Li; Brian R. Sturtevant; Jian Yang; Bo Z. Shang; Eric J. Gustafson; David J. Mladenoff

    2005-01-01

    LANDIS 4.0 is new-generation software that simulates forest landscape change over large spatial and temporal scales. It is used to explore how disturbances, succession, and management interact to determine forest composition and pattern. Also describes software architecture, model assumptions and provides detailed instructions on the use of the model.

  3. Summer evapotranspiration trends as related to time following logging of high elevation forest stands in Sierra Nevada

    Science.gov (United States)

    Robert R. Ziemer

    1963-01-01

    Abstract - The quantity of summer soil moisture loss from logged forest openings was related to the length of time since the creation of the opening in a study made in the subalpine forest zone of the Sierra Nevada west-side near the Central Sierra Snow Laboratory, California, within the elevational range of 6,000 to 7,000 feet. Soil moisture depletion was measured in...

  4. The impact of lianas on the carbon cycle of tropical forests: a modeling study using the Ecosystem Demography model

    Science.gov (United States)

    di Porcia e Brugnera, M.; Longo, M.; Verbeek, H.

    2017-12-01

    Lianas are an important component of tropical forests, constituting up to 40% of the woody stems and about 35% of the woody species. Tropical forests have been experiencing large-scale structural changes, including an increase in liana abundance and biomass. This may eventually reduce the projected carbon sink of tropical forests. Despite their crucial role no single terrestrial ecosystem model has included lianas so far. Here, we present the very first implementation of lianas in the Ecosystem Demography model (ED2). ED2 is able to represent the competition for water and light between different vegetation types at the regional level. Our new implementation of ED2 is hence suitable to address important questions such as the impact of lianas on the tropical forest carbon balance. We validated the model against forest inventory and eddy covariance flux data at a dry seasonal site (Barro Colorado Island, Panama), and at a wet rainforest site (Paracou, French Guiana). The model was able to represent size structure and carbon accumulation rates. We also evaluated the impact of the unique allocation strategy of lianas on their competitive ability. Lianas invest only a small fraction of their carbon for structural tissues when compared to trees. As a result, lianas benefit from an extra amount of available carbon, however the trade-offs of low allocation on structural tissues are not yet well understood. We are currently investigating a number of hypotheses, including the possibility for lianas to have high turnover rates for leaves and fine roots, or to have high mortality rates due to the loss of structural support when trees die. As such our model allows us to get a better understanding of the role of lianas in the tropical forest carbon cycle.

  5. Simulation of Forest Carbon Fluxes Using Model Incorporation and Data Assimilation

    OpenAIRE

    Min Yan; Xin Tian; Zengyuan Li; Erxue Chen; Xufeng Wang; Zongtao Han; Hong Sun

    2016-01-01

    This study improved simulation of forest carbon fluxes in the Changbai Mountains with a process-based model (Biome-BGC) using incorporation and data assimilation. Firstly, the original remote sensing-based MODIS MOD_17 GPP (MOD_17) model was optimized using refined input data and biome-specific parameters. The key ecophysiological parameters of the Biome-BGC model were determined through the Extended Fourier Amplitude Sensitivity Test (EFAST) sensitivity analysis. Then the optimized MOD_17 mo...

  6. 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

  7. Aboveground Biomass and Dynamics of Forest Attributes using LiDAR Data and Vegetation Model

    Science.gov (United States)

    V V L, P. A.

    2015-12-01

    In recent years, biomass estimation for tropical forests has received much attention because of the fact that regional biomass is considered to be a critical input to climate change. Biomass almost determines the potential carbon emission that could be released to the atmosphere due to deforestation or conservation to non-forest land use. Thus, accurate biomass estimation is necessary for better understating of deforestation impacts on global warming and environmental degradation. In this context, forest stand height inclusion in biomass estimation plays a major role in reducing the uncertainty in the estimation of biomass. The improvement in the accuracy in biomass shall also help in meeting the MRV objectives of REDD+. Along with the precise estimate of biomass, it is also important to emphasize the role of vegetation models that will most likely become an important tool for assessing the effects of climate change on potential vegetation dynamics and terrestrial carbon storage and for managing terrestrial ecosystem sustainability. Remote sensing is an efficient way to estimate forest parameters in large area, especially at regional scale where field data is limited. LIDAR (Light Detection And Ranging) provides accurate information on the vertical structure of forests. We estimated average tree canopy heights and AGB from GLAS waveform parameters by using a multi-regression linear model in forested area of Madhya Pradesh (area-3,08,245 km2), India. The derived heights from ICESat-GLAS were correlated with field measured tree canopy heights for 60 plots. Results have shown a significant correlation of R2= 74% for top canopy heights and R2= 57% for stand biomass. The total biomass estimation 320.17 Mt and canopy heights are generated by using random forest algorithm. These canopy heights and biomass maps were used in vegetation models to predict the changes biophysical/physiological characteristics of forest according to the changing climate. In our study we have

  8. [Ecological benefit evaluation of urban forests in Shenyang City based on QuickBird image and CITYgreen model].

    Science.gov (United States)

    Liu, Chang-Fu; He, Xing-Yuan; Chen, Wei; Zhao, Gui-Ling; Li, Ling; Xu, Wen-Duo

    2008-09-01

    Based on the urban forest coverage data interpreted from QuickBird image (2006) and the CITYgreen model, the benefits of Shenyang urban forest types with different canopy closure in carbon fixation and pollutant removal were investigated by means of sampling strategy. The results showed that the total amount of carbon storage, annual carbon sequestration, annual air pollutant removal, and their corresponding values were 0.51 Tg, 6858.20 Mg x a-1), 556.04 Mg x a(-1) 1.26 x 10(8) Yuan, 1.72 x 10(6) Yuan, and 0.22 x 10(8) Yuan, respectively. Among the urban forest types in Shenyang City, ecological and public welfare forest (E) contributed most to the carbon fixation and air pollutant removal. The carbon density decreased in the order of S (subordinated forest) > L (landscape and relaxation forest) > P (production and management forest) > E > R (road forest), annual carbon sequestration was in the order of P > L > E > S > R, and annual air pollutant removal was in the order of P > L > S > E > R. The carbon density of different urban forest types was closely related to their structural complexity. For the forests with high canopy closure, both the annual carbon sequestration and the annual pollutant removal were high; while for those with lower canopy closure, these two characteristics were dependent on the structural complexity of the forests.

  9. Validation of 3D-CMCC Forest Ecosystem Model (v.5.1) against eddy covariance data for 10 European forest sites

    DEFF Research Database (Denmark)

    Collalti, A.; Marconi, S.; Ibrom, Andreas

    2016-01-01

    This study evaluates the performances of the new version (v.5.1) of 3D-CMCC Forest Ecosystem Model (FEM) in simulating gross primary productivity (GPP), against eddy covariance GPP data for 10 FLUXNET forest sites across Europe. A new carbon allocation module, coupled with new both phenological...... over Europe without a site-related calibration, the model has been deliberately parametrized with a single set of species-specific parametrizations for each forest ecosystem. The model consistently reproduces both in timing and in magnitude daily and monthly GPP variability across all sites......, with the exception of the two Mediterranean sites. We find that 3D-CMCC FEM tends to better simulate the timing of inter-annual anomalies than their magnitude within measurements' uncertainty. In six of eight sites where data are available, the model well reproduces the 2003 summer drought event. Finally, for three...

  10. Drought as a driver of declining boreal forest growth: Integrating forest inventory measurements with models to gain insight into underlying mechanisms

    Science.gov (United States)

    Trugman, A. T.; Medvigy, D.; Anderegg, W.; Caspersen, J.; Zeng, H.; Pacala, S. W.

    2016-12-01

    Boreal forests contain over 30% of Earth's terrestrial carbon and are an important component of the land carbon sink. However, the future ability of the boreal forest to maintain a net carbon sink is uncertain and depends on potentially compensating interactions of CO2 fertilization, warmer temperatures, and hotter drought conditions. Observational studies have attributed drought as a major driver of recent declines in growth and increases in mortality in many parts of the North American boreal forest. Yet, most vegetation models have a simplistic representation of vegetation water stress and fail to capture drought-associated growth and mortality trends, impacting our ability to accurately forecast the effects of climate change on the boreal forest. Here, we show additional evidence for widespread declines in boreal tree growth and increasing insect-related mortality in aspen trees based on a mixed model analysis of the Cooperative Alaska Forest Inventory. Our findings indicate that the growth decline is controlled by high midsummer potential evapotranspiration that overpowers any CO2 fertilization signal. We also observe a possible shift in the distribution of angiosperm and gymnosperm, a biological transition that could impact long-term local carbon dynamics. Using insight gained from our mixed model analysis, we perform a regional-scale model evaluation using the boreal forest version of Ecosystem Demography model 2 that includes a dynamic soil organic layer, 7 boreal-specific plant functional types, and a fully mechanistic plant hydraulic scheme. We then use both the Alaskan and Canadian Forest Inventories to constrain our hypotheses and assess whether drought related growth declines can be better attributed to tree drought response from (1) carbon starvation, (2) permanent damage of hydraulic machinery, or (3) delayed recovery of hydraulic machinery. Under each of these scenarios we forecast how drought potentially impacts decadal-scale boreal carbon dynamics.

  11. Using the Global Forest Products Model (GFPM version 2016 with BPMPD)

    Science.gov (United States)

    Joseph Buongiorno; Shushuai   Zhu

    2016-01-01

     The GFPM is an economic model of global production, consumption and trade of forest products. The original formulation and several applications are described in Buongiorno et al. (2003). However, subsequent versions, including the GFPM 2016 reflect significant changes and extensions. The GFPM 2016 software uses the...

  12. Modelling and mapping the suitability of European forest formations at 1-km resolution

    DEFF Research Database (Denmark)

    Casalegno, Stefano; Amatulli, Giuseppe; Bastrup-Birk, Annemarie

    2011-01-01

    Proactive forest conservation planning requires spatially accurate information about the potential distribution of tree species. The most cost-efficient way to obtain this information is habitat suitability modelling i.e. predicting the potential distribution of biota as a function of environment...

  13. Modeling potential evapotranspiration of two forested watersheds in the southern Appalachians

    Science.gov (United States)

    L.Y. Rao; G. Sun; C.R. Ford; J.M. Vose

    2011-01-01

    Global climate change has direct impacts on watershed hydrology through altering evapotranspiration (ET) processes at multiple scales. There are many methods to estimate forest ET with models, but the most practical and the most popular one is the potential ET (PET) based method. However, the choice of PET methods for AET estimation remains challenging. This study...

  14. Random forests as cumulative effects models: A case study of lakes and rivers in Muskoka, Canada.

    Science.gov (United States)

    Jones, F Chris; Plewes, Rachel; Murison, Lorna; MacDougall, Mark J; Sinclair, Sarah; Davies, Christie; Bailey, John L; Richardson, Murray; Gunn, John

    2017-10-01

    Cumulative effects assessment (CEA) - a type of environmental appraisal - lacks effective methods for modeling cumulative effects, evaluating indicators of ecosystem condition, and exploring the likely outcomes of development scenarios. Random forests are an extension of classification and regression trees, which model response variables by recursive partitioning. Random forests were used to model a series of candidate ecological indicators that described lakes and rivers from a case study watershed (The Muskoka River Watershed, Canada). Suitability of the candidate indicators for use in cumulative effects assessment and watershed monitoring was assessed according to how well they could be predicted from natural habitat features and how sensitive they were to human land-use. The best models explained 75% of the variation in a multivariate descriptor of lake benthic-macroinvertebrate community structure, and 76% of the variation in the conductivity of river water. Similar results were obtained by cross-validation. Several candidate indicators detected a simulated doubling of urban land-use in their catchments, and a few were able to detect a simulated doubling of agricultural land-use. The paper demonstrates that random forests can be used to describe the combined and singular effects of multiple stressors and natural environmental factors, and furthermore, that random forests can be used to evaluate the performance of monitoring indicators. The numerical methods presented are applicable to any ecosystem and indicator type, and therefore represent a step forward for CEA. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  15. Using a network model to assess risk of forest pest spread via recreational travel

    Science.gov (United States)

    Frank H. Koch; Denys Yemshanov; Robert A. Haack; Roger D. Magarey

    2014-01-01

    Long-distance dispersal pathways, which frequently relate to human activities, facilitate the spread of alien species. One pathway of concern in North America is the possible spread of forest pests in firewood carried by visitors to campgrounds or recreational facilities. We present a network model depicting the movement of campers and, by extension, potentially...

  16. Calibration of the L-MEB model over a coniferous and a deciduous forest

    DEFF Research Database (Denmark)

    Grant, Jennifer P.; Saleh-Contell, Kauzar; Wigneron, Jean-Pierre

    2008-01-01

    In this paper, the L-band Microwave Emission of the Biosphere (L-MEB) model used in the Soil Moisture and Ocean Salinity (SMOS) Level 2 Soil Moisture algorithm is calibrated using L-band (1.4 GHz) microwave measurements over a coniferous (Pine) and a deciduous (mixed/Beech) forest. This resulted...

  17. Generalization of Faustmann's Formula for Stochastic Forest Growth and Prices with Markov Decision Process Models

    Science.gov (United States)

    Joseph Buongiorno

    2001-01-01

    Faustmann's formula gives the land value, or the forest value of land with trees, under deterministic assumptions regarding future stand growth and prices, over an infinite horizon. Markov decision process (MDP) models generalize Faustmann's approach by recognizing that future stand states and prices are known only as probabilistic distributions. The...

  18. Review of nitrogen fate models applicable to forest landscapes in the Southern U.S.

    Science.gov (United States)

    D. M. Amatya; C. G. Rossi; A. Saleh; Z. Dai; M. A. Youssef; R. G. Williams; D. D. Bosch; G. M. Chescheir; G. Sun; R. W. Skaggs; C. C. Trettin; E. D. Vance; J. E. Nettles; S. Tian

    2013-01-01

    Assessing the environmental impacts of fertilizer nitrogen (N) used to increase productivity in managed forests is complex due to a wide range of abiotic and biotic factors affecting its forms and movement. Models developed to predict fertilizer N fate (e.g., cycling processes) and water quality impacts vary widely in their design, scope, and potential application. We...

  19. A framework for evaluating forest landscape model predictions using empirical data and knowledge

    Science.gov (United States)

    Wen J. Wang; Hong S. He; Martin A. Spetich; Stephen R. Shifley; Frank R. Thompson; William D. Dijak; Qia. Wang

    2014-01-01

    Evaluation of forest landscape model (FLM) predictions is indispensable to establish the credibility of predictions. We present a framework that evaluates short- and long-term FLM predictions at site and landscape scales. Site-scale evaluation is conducted through comparing raster cell-level predictions with inventory plot data whereas landscape-scale evaluation is...

  20. Bibliography of forest water yields, flooding issues, and the hydrologic modeling of extreme flood events

    Science.gov (United States)

    Mark H. Eisenbies; M.B. Adams; W. Michael Aust; James A. Burger

    2007-01-01

    Floods continue to cause significant damage in the United States and elsewhere, and questions about the causes of flooding continue to be debated. A significant amount of research has been conducted on the relationship between forest management activities and water yield, peak flows, and flooding; somewhat less research has been conducted on the modeling of these...

  1. Model forest landscape change in the Missouri Ozarks under alternative management practices

    Science.gov (United States)

    Stephen R. Shifley; Frank R. Thompson; David R. Larsen; William D. Dijak

    2000-01-01

    We used a spatially explicit landscape model, LANDIS, to simulate the effects of five management alternatives on a 3216 ha forest landscape in southeast Missouri, USA. We compared management alternatives among two intensities of even-aged management with clearcutting, uneven-aged management with group selection harvest, a mixture of even- and uneven-aged management,...

  2. Modeling forest ecosystem changes resulting from surface coal mining in West Virginia

    Science.gov (United States)

    John Brown; Andrew J. Lister; Mary Ann Fajvan; Bonnie Ruefenacht; Christine Mazzarella

    2012-01-01

    The objective of this project is to assess the effects of surface coal mining on forest ecosystem disturbance and restoration in the Coal River Subbasin in southern West Virginia. Our approach is to develop disturbance impact models for this subbasin that will serve as a case study for testing the feasibility of integrating currently available GIS data layers, remote...

  3. Challenges of forest landscape modeling - simulating large landscapes and validating results

    Science.gov (United States)

    Hong S. He; Jian Yang; Stephen R. Shifley; Frank R. Thompson

    2011-01-01

    Over the last 20 years, we have seen a rapid development in the field of forest landscape modeling, fueled by both technological and theoretical advances. Two fundamental challenges have persisted since the inception of FLMs: (1) balancing realistic simulation of ecological processes at broad spatial and temporal scales with computing capacity, and (2) validating...

  4. Estimating forest variables from top-of-atmosphere radiance satellite measurements using coupled radiative transfer models

    NARCIS (Netherlands)

    Laurent, V.C.E.; Verhoef, W.; Clevers, J.G.P.W.; Schaepman, M.E.

    2011-01-01

    Traditionally, it is necessary to pre-process remote sensing data to obtain top of canopy (TOC) reflectances before applying physically-based model inversion techniques to estimate forest variables. Corrections for atmospheric, adjacency, topography, and surface directional effects are applied

  5. Evaluating the SWAT model for a low-gradient forested watershed in coastal South Carolina

    Science.gov (United States)

    D.M. Amatya; M.K. Jha.

    2011-01-01

    Modeling the hydrology of low�]gradient forested watersheds on shallow, poorly drained soils of the coastal plain is a challenging task due to complexities in watershed delineation, microtopography, evapotranspiration, runoff generation processes and pathways including flooding and submergence caused by tropical storms, and complexity of vegetation species....

  6. The influence of climate changes on carbon cycle in the russian forests. Data inventory and long-scale model prognoses

    Energy Technology Data Exchange (ETDEWEB)

    Kokorin, A.O.; Nazarov, I.M.; Lelakin, A.L. [Inst. Global Climate and Ecology, Moscow (Russian Federation)

    1995-12-31

    The growing up climate changes arise the question about reaction of forests. Forests cover 770 Mha in Russia and are giant carbon reservoir. Climate changes cause disbalance in carbon budget that give additional CO{sub 2} exchange between forests and the atmosphere. The aim of the work is estimation of these fluxes. This problem is directly connected with an GHG inventory, vulnerability and mitigation assessment, which are necessary for future Russian Reports to UN FCCC. The work includes the following steps: (1) Collection of literature data as well as processing of the experimental data on influence of climate changes on forests, (2) Calculation of carbon budget as base for calculations of CO{sub 2} fluxes, (3) Developing of new version of CCBF (Carbon and Climate in Boreal Forests) model, (4) Model estimations of current and future CO{sub 2} fluxes caused by climate changes, forest cuttings, fires and reforestation

  7. Measuring and modelling the impact of the bark beetle forest disturbance on snow accumulation and ablation at a plot scale

    Science.gov (United States)

    Jenicek, Michal; Matejka, Ondrej; Hotovy, Ondrej

    2017-04-01

    The knowledge of water volume stored in the snowpack and its spatial distribution is important to predict the snowmelt runoff. The objective of this study was to quantify the role of different forest structures on the snowpack distribution at a plot scale during snow accumulation and snow ablation periods. Special interest was put in the role of the forest affected by the bark beetle (Ips typographus). We performed repeated detailed manual field survey at selected mountain plots with different canopy structure located at the same elevation and without influence of topography and wind on the snow distribution. The forest canopy structure was described using parameters calculated from hemispherical photographs, such as canopy closure, leaf area index (LAI) and potential irradiance. Additionally, we used shortwave radiation measured using CNR4 Net radiometers placed in plots with different canopy structure. Two snow accumulation and ablation models were set-up to simulate the snow water equivalent (SWE) in plots with different vegetation cover. First model was physically-based using the energy balance approach, second model was conceptual and it was based on the degree-day approach. Both models accounted for snow interception in different forest types using LAI as a parameter. The measured SWE in the plot with healthy forest was on average by 41% lower than in open area during snow accumulation period. The disturbed forest caused the SWE reduction by 22% compared to open area indicating increasing snow storage after forest defoliation. The snow ablation in healthy forest was by 32% slower compared to open area. On the contrary, the snow ablation in disturbed forest (due to the bark beetle) was on average only by 7% slower than in open area. The relative decrease in incoming solar radiation in the forest compared to open area was much bigger compared to the relative decrease in snowmelt rates. This indicated that the decrease in snowmelt rates cannot be explained only

  8. Extrapolating carbon dynamics of tropical dry forests into future climates: improving simulation models with empirical observations

    Science.gov (United States)

    Medvigy, David; Waring, Bonnie; Vargas, German; Xu, Xiangtao; Smith, Christina; Becknell, Justin; Trierweiler, Annette; Brodribb, Timothy; Powers, Jennifer

    2017-04-01

    Tropical dry forests occur in areas with warm temperatures and a pronounced dry season with little to no rainfall that lasts 3 to 7 months. The potential area covered by this biome is vast: globally, 47% of all forest occurs in tropical and subtropical latitudes, and of all tropical forests approximately 42% are classified as dry forests. Throughout the last several centuries, the area covered by tropical dry forests has been dramatically reduced through conversion to grazing and croplands, and they are now considered the most threatened tropical biome. However, in many regions, tropical dry forests are now growing back. There is growing concern that this recovery process will be strongly impacted by climate variability and change. Observations show that climate is changing in the seasonal tropics, and climate models forecast that neotropical dry forests will receive significantly less rainfall in the 21st century than in the 20th century. Rates of nitrogen deposition are also changing rapidly in this sector, and the fertility of some soils may still be recovering from past land use. We are engaged in several efforts to understand how water and nutrients limit the productivity of these forests, including manipulative experiments, modeling, and investigation of responses to natural climate variability. In 2015, at a well-characterized site in Guanacaste, Costa Rica, we established a full-factorial fertilization experiment with N and P in diverse mature forest stands. Initial responses highlight stronger ecosystem sensitivity to P addition than to N addition. Intriguingly, pre-experiment numerical simulations with a mechanistic ecosystem model had indicated the reverse. Work is ongoing to use field observations to better represent critical processes in the model, and ultimately to improve the model's sensitivity to nutrients and water. In addition, in 2016, we established a full factorial nutrient addition and drought experiment in plantations. Thus far, soil

  9. Modelling deforestation trends in Costa Rica and predicting future forest sustainability

    Science.gov (United States)

    Stan, Kayla; Sanchez, Arturo

    2017-04-01

    Deforestation in Costa Rica has historically varied between the original degradation of primary forest due to land-based industries, followed by secondary regrowth. The regeneration of forests largely came into effect with incentive based programs such as payments for ecosystem services, creation of large protected areas, and a new industry of ecotourism in the country. Given the changes that have occurred within the last 50 years from heavy deforestation pressures to regeneration patterns, and a correlation between deforestation and policy/economic influences, it is important to understand the historical changes that have occurred and how the forests will change in the future, which provides the objective of this study. Future projections are increasingly important given changes in the global socio-political structure, climatic change, and the ever increasing globalization of capitalistic endeavours. The trajectory of the forest in the country can also serve as a way to track both these global pressures on the natural landscape in Costa Rica, and as a proxy for how to manage deforestation in other similar political and geographic areas of the tropics. To determine the historical deforestation trends and link them to the different biogeophysical and socioeconomic variables, forest maps from 1960-2013 were used in the Dinamica Environment for Geoprocessing Objects (Dinamica EGO) to create deforestation models for Costa Rica. Dinamica EGO is a cellular automata model which utilizes Bayesian statistics and expert opinion to replicate both patterns and quantities of land cover change over time with both static and dynamic variables. Additional legislative variables can be used to track how political pressures shift deforestation both spatially and temporally. The historical model was built and analyzed for changes in landscape metrics such as patch size and distance between 1960 and 2013. After validation of the model's ability to replicate patterns, first between 2005

  10. Comparison Between Surf and Multi-Shock Forest Fire High Explosive Burn Models

    Energy Technology Data Exchange (ETDEWEB)

    Greenfield, Nicholas Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-18

    PAGOSA1 has several different burn models used to model high explosive detonation. Two of these, Multi-Shock Forest Fire and Surf, are capable of modeling shock initiation. Accurately calculating shock initiation of a high explosive is important because it is a mechanism for detonation in many accident scenarios (i.e. fragment impact). Comparing the models to pop-plot data give confidence that the models are accurately calculating detonation or lack thereof. To compare the performance of these models, pop-plots2 were created from simulations where one two cm block of PBX 9502 collides with another block of PBX 9502.

  11. Comparative analysis of the actual evapotranspiration of Flemish forest and cropland, using the soil water balance model WAVE

    Directory of Open Access Journals (Sweden)

    W. W. Verstraeten

    2005-01-01

    Full Text Available This paper focuses on the quantification of the green – vegetation related – water flux of forest stands in the temperate lowland of Flanders. The underlying reason of the research was to develop a methodology for assessing the impact of forests on the hydrologic cycle in comparison to agriculture. The tested approach for calculating the water use by forests was based on the application of the soil water balance model WAVE. The study involved the collection of data from 14 forest stands, the calibration and validation of the WAVE model, and the comparison of the water use (WU components – transpiration, soil and interception evaporation – between forest and cropland. For model calibration purposes simulated and measured time series of soil water content at different soil depths, period March 2000–August 2001, were compared. A multiple-site validation was conducted as well. Actual tree transpiration calculated with sap flow measurements in three forest stands gave similar results for two of the three stands of pine (Pinus sylvestris L., but WAVE overestimated the actual measured transpiration for a stand of poplar (Populus sp.. A useful approach to compare the WU components of forest versus cropland is scenario analysis based on the validated WAVE model. The statistical Profile Analysis method was implemented to explore and analyse the simulated WU time series. With an average annual rainfall of 819 mm, the results reveal that forests in Flanders consume more water than agricultural crops. A 30 years average of 491 mm for 10 forests stands versus 398 mm for 10 cropped agricultural fields was derived. The WU components, on yearly basis, also differ between the two land use types (transpiration: 315 mm for forest and 261 mm for agricultural land use; soil evaporation: 47 mm and 131 mm, for forest and cropland, respectively. Forest canopy interception evaporation was estimated at 126 mm, while it was negligible for cropland.

  12. Forest operations planning by using RTK-GPS based digital elevation model

    Directory of Open Access Journals (Sweden)

    Neşe Gülci

    2015-07-01

    Full Text Available Having large proportion of forests in mountainous terrain in Turkey, the logging methods that not only minimize operational costs but also minimize environmental damages should be determined in forest operations planning. In a case where necessary logging equipment and machines are available, ground slope is the most important factor in determining the logging method. For this reason, accurate, up to date, and precise ground slope data is very crucial in the success of forest operations planning. In recent years, high-resolution Digital Elevation Models (DEM can be generated for forested areas by using Real Time Kinematic (RTK GPS method and these DEMs can be used to develop precise slope maps. In this study, high-resolution DEM was developed by RTK-GPS method to generate precise slope map in a sample area. Then, the slope map was classified into slope classes specified by IUFRO in order to assist forest operations planning. According to the results, logging methods that are suitable for very steep and steep terrain conditions (i.e. skyline logging, cable pulling, and chute systems should be preferred in 48.1% of the study area. It was also found that logging methods that are suitable for terrain with medium slope (i.e. skidding and cable pulling and gentle slope (i.e. skidding and mobile winch should be preferred in 34.1% and 17.8% of the study area, respectively.

  13. Distribution and Conservation of Davilla (Dilleniaceae in Brazilian Atlantic Forest Using Ecological Niche Modeling

    Directory of Open Access Journals (Sweden)

    Ismael Martins Pereira

    2014-01-01

    Full Text Available We have modeled the ecological niche for 12 plant species belonging to the genus Davilla (Dilleniaceae which occur in the Atlantic Forest of Brazil. This group includes endemic species lianas threatened by extinction and is therefore a useful indicator for forest areas requiring conservation. The aims are to compare the distribution and richness of species within the protected areas, assessing the degree of protection and gap analysis of reserves for this group. We used the Maxent algorithm with environmental and occurrence data, and produced geographic distribution maps. The results show that high species richness occurs in forest and coastal forest of Espírito Santo to Bahia states. The endemic species comprise D. flexuosa, D. macrocarpa, D. flexuosa, D. grandifolia, and D. sessilifolia. In the Atlantic Forest of southeastern Brazil, the following endemic species occur: D. tintinnabulata and D. glaziovii, with this latter species being included in the “red list” due habitat loss and predatory extractivism. The indicators of species richness in the coastal region of Bahia correspond with floristic inventories that point to this area having a high biodiversity. Although this region has several protected areas, there are gaps in reserves, which, combined with anthropogenic threats and fragmentation, have caused several problems for biodiversity.

  14. Hydro-economic modeling of the role of forests on water resources production in Andalusia, Spain

    Science.gov (United States)

    Beguería, Santiago; Serrano-Notivoli, Roberto; Álvarez-Palomino, Alejandro; Campos, Pablo

    2014-05-01

    The development of more refined information tools is a pre-requisite for supporting decision making in the context of integrated water resources management. Among these tools, hydro-economic models are favoured because they allow integrating the ecological, hydrological, infrastructure and economic aspects into a coherent, scientifically-informed framework. We present a case study that assesses physically the water resources of forest lands of the Andalusia region in Spain and conducts an economic environmental income and asset valuation of the forest surface water yield. We show how, based on available hydrologic and economic data, we can develop a comprehensive water account for all the forest lands at the regional scale. This forest water environmental valuation is part of the larger RECAMAN project, which aims at providing a robust and easily replicable accounting tool to evaluate yearly the total income an capital generated by the forest land, encompassing all measurable sources of private and public incomes (timber and cork production, auto-consumption, recreational activities, biodiversity conservation, carbon sequestration, water production, etc.). Only a comprehensive integrated tool such as the one built within the RECAMAN project may serve as a basis for the development of integrated policies such as those internationally agreed and recommended for the management of water resources.

  15. Heterogeneous movement of insectivorous Amazonian birds through primary and secondary forest: A case study using multistate models with radiotelemetry data

    Science.gov (United States)

    Hines, James; Powell, Luke L.; Wolfe, Jared D.; Johnson, Erik l.; Nichols, James D.; Stouffer, Phillip C.

    2015-01-01

    Given rates of deforestation, disturbance, and secondary forest accumulation in tropical rainforests, there is a great need to quantify habitat use and movement among different habitats. This need is particularly pronounced for animals most sensitive to disturbance, such as insectivorous understory birds. Here we use multistate capture–recapture models with radiotelemetry data to determine the successional stage at which within-day movement probabilities of Amazonian birds in secondary forest are similar to those in primary forest. We radio-tracked three common understory insectivore species in primary and secondary forest at the Biological Dynamics of Forest Fragments project near Manaus, Brazil: two woodcreepers, Glyphorynchus spirurus (n = 19) andXiphorhynchus pardalotus (n = 18), and the terrestrial antthrush Formicarius colma(n = 19). Forest age was a strong predictor of fidelity to a given habitat. All three species showed greater fidelity to primary forest than to 8–14-year-old secondary forest, indicating the latter’s relatively poor quality. The two woodcreeper species used 12–18-year-old secondary forest in a manner comparable to continuous forest, but F. colmaavoided moving even to 27–31-year-old secondary forest—the oldest at our site. Our results suggest that managers concerned with less sensitive species can assume that forest reserves connected by 12–18-year-old secondary forest corridors are effectively connected. On the other hand, >30 years are required after land abandonment before secondary forest serves as a primary forest-like conduit for movement by F. colma; more sensitive terrestrial insectivores may take longer still.

  16. Sequential Fragmentation of Pleistocene Forests in an East Africa Biodiversity Hotspot: Chameleons as a Model to Track Forest History

    OpenAIRE

    Measey, G. John; Tolley, Krystal A.

    2011-01-01

    Background The Eastern Arc Mountains (EAM) is an example of naturally fragmented tropical forests, which contain one of the highest known concentrations of endemic plants and vertebrates. Numerous paleo-climatic studies have not provided direct evidence for ancient presence of Pleistocene forests, particularly in the regions in which savannah presently occurs. Knowledge of the last period when forests connected EAM would provide a sound basis for hypothesis testing of vicariance and dispersal...

  17. [Forest lighting fire forecasting for Daxing'anling Mountains based on MAXENT model].

    Science.gov (United States)

    Sun, Yu; Shi, Ming-Chang; Peng, Huan; Zhu, Pei-Lin; Liu, Si-Lin; Wu, Shi-Lei; He, Cheng; Chen, Feng

    2014-04-01

    Daxing'anling Mountains is one of the areas with the highest occurrence of forest lighting fire in Heilongjiang Province, and developing a lightning fire forecast model to accurately predict the forest fires in this area is of importance. Based on the data of forest lightning fires and environment variables, the MAXENT model was used to predict the lightning fire in Daxing' anling region. Firstly, we studied the collinear diagnostic of each environment variable, evaluated the importance of the environmental variables using training gain and the Jackknife method, and then evaluated the prediction accuracy of the MAXENT model using the max Kappa value and the AUC value. The results showed that the variance inflation factor (VIF) values of lightning energy and neutralized charge were 5.012 and 6.230, respectively. They were collinear with the other variables, so the model could not be used for training. Daily rainfall, the number of cloud-to-ground lightning, and current intensity of cloud-to-ground lightning were the three most important factors affecting the lightning fires in the forest, while the daily average wind speed and the slope was of less importance. With the increase of the proportion of test data, the max Kappa and AUC values were increased. The max Kappa values were above 0.75 and the average value was 0.772, while all of the AUC values were above 0.5 and the average value was 0. 859. With a moderate level of prediction accuracy being achieved, the MAXENT model could be used to predict forest lightning fire in Daxing'anling Mountains.

  18. Improving predictions of tropical forest response to climate change through integration of field studies and ecosystem modeling

    Science.gov (United States)

    Feng, Xiaohui; Uriarte, María; González, Grizelle; Reed, Sasha C.; Thompson, Jill; Zimmerman, Jess K.; Murphy, Lora

    2018-01-01

    Tropical forests play a critical role in carbon and water cycles at a global scale. Rapid climate change is anticipated in tropical regions over the coming decades and, under a warmer and drier climate, tropical forests are likely to be net sources of carbon rather than sinks. However, our understanding of tropical forest response and feedback to climate change is very limited. Efforts to model climate change impacts on carbon fluxes in tropical forests have not reached a consensus. Here we use the Ecosystem Demography model (ED2) to predict carbon fluxes of a Puerto Rican tropical forest under realistic climate change scenarios. We parameterized ED2 with species-specific tree physiological data using the Predictive Ecosystem Analyzer workflow and projected the fate of this ecosystem under five future climate scenarios. The model successfully captured inter-annual variability in the dynamics of this tropical forest. Model predictions closely followed observed values across a wide range of metrics including above-ground biomass, tree diameter growth, tree size class distributions, and leaf area index. Under a future warming and drying climate scenario, the model predicted reductions in carbon storage and tree growth, together with large shifts in forest community composition and structure. Such rapid changes in climate led the forest to transition from a sink to a source of carbon. Growth respiration and root allocation parameters were responsible for the highest fraction of predictive uncertainty in modeled biomass, highlighting the need to target these processes in future data collection. Our study is the first effort to rely on Bayesian model calibration and synthesis to elucidate the key physiological parameters that drive uncertainty in tropical forests responses to climatic change. We propose a new path forward for model-data synthesis that can substantially reduce uncertainty in our ability to model tropical forest responses to future climate.

  19. Developments to the Sylvan stand structure model to describe wood quality changes in southern bottomland hardwood forests because of forest management

    Science.gov (United States)

    Ian R. Scott

    2009-01-01

    Growth models can produce a wealth of detailed information that is often very difficult to perceive because it is frequently presented either as summary tables, stand view or landscape view visualizations. We have developed new tools for use with the Sylvan model (Larsen 1994) that allow the analysis of wood-quality changes as a consequence of forest management....

  20. Human radiation dose resulting from forests contaminated by radionuclides: generic model and applications to the Chernobyl ecosystems

    International Nuclear Information System (INIS)

    Linkov, I.; Harvard Univ., Cambridge, MA; Schell, W.R.

    1996-01-01

    Forest ecosystems have been found to contribute significantly to the human radiation dose in the intermediate and long teens following radionuclide releases. Evaluation of the internal and external radiation dose for these critical population groups requires knowledge of radionuclide transport processes in forest ecosystems, as well as the extent of forest utilization by these populations. The high complexity of the problem requires the use of models to define and analyze the properties of the forest as well as to evaluate the ecosystem response to possible human intervention. A generic FORESTPATH model is used to calculate the internal and external radiation doses for different critical groups of consumers at different times following radionuclide release. The model is tested using the information available for contaminated forests in Belarus. Uncertainty of the model predictions are estimated by means of Monte-Carlo simulations. (author)

  1. Effect of different tree mortality patterns on stand development in the forest model SIBYLA

    Directory of Open Access Journals (Sweden)

    Trombik Jiří

    2016-09-01

    Full Text Available Forest mortality critically affects stand structure and the quality of ecosystem services provided by forests. Spruce bark beetle (Ips typographus generates rather complex infestation and mortality patterns, and implementation of such patterns in forest models is challenging. We present here the procedure, which allows to simulate the bark beetle-related tree mortality in the forest dynamics model Sibyla. We explored how sensitive various production and stand structure indicators are to tree mortality patterns, which can be generated by bark beetles. We compared the simulation outputs for three unmanaged forest stands with 40, 70 and 100% proportion of spruce as affected by the disturbance-related mortality that occurred in a random pattern and in a patchy pattern. The used tree species and age class-specific mortality rates were derived from the disturbance-related mortality records from Slovakia. The proposed algorithm was developed in the SQLite using the Python language, and the algorithm allowed us to define the degree of spatial clustering of dead trees ranging from a random distribution to a completely clustered distribution; a number of trees that died in either mode is set to remain equal. We found significant differences between the long-term developments of the three investigated forest stands, but we found very little effect of the tested mortality modes on stand increment, tree species composition and diversity, and tree size diversity. Hence, our hypothesis that the different pattern of dead trees emergence should affect the competitive interactions between trees and regeneration, and thus affect selected productivity and stand structure indicators was not confirmed.

  2. Modeling transcriptional networks regulating secondary growth and wood formation in forest trees.

    Science.gov (United States)

    Liu, Lijun; Filkov, Vladimir; Groover, Andrew

    2014-06-01

    The complex interactions among the genes that underlie a biological process can be modeled and presented as a transcriptional network, in which genes (nodes) and their interactions (edges) are shown in a graphical form similar to a wiring diagram. A large number of genes have been identified that are expressed during the radial woody growth of tree stems (secondary growth), but a comprehensive understanding of how these genes interact to influence woody growth is currently lacking. Modeling transcriptional networks has recently been made tractable by next-generation sequencing-based technologies that can comprehensively catalog gene expression and transcription factor-binding genome-wide, but has not yet been extensively applied to undomesticated tree species or woody growth. Here we discuss basic features of transcriptional networks, approaches for modeling biological networks, and examples of biological network models developed for forest trees to date. We discuss how transcriptional network research is being developed in the model forest tree genus, Populus, and how this research area can be further developed and applied. Transcriptional network models for forest tree secondary growth and wood formation could ultimately provide new predictive models to accelerate hypothesis-driven research and develop new breeding applications. © 2013 Scandinavian Plant Physiology Society.

  3. Agent-Based Modeling of Harvest Decisions by Small Scale Forest Landowners in Maine, USA

    Directory of Open Access Journals (Sweden)

    Jessica E. Leahy

    2013-01-01

    Full Text Available Small-scale forests are an excellent example of coupled social-ecological systems, which involve human and biophysical subsystems with complex two-way feedback interactions. The multifaceted nature of landowner decisions drives a significant need to better understand decision-making processes, reactions to policy, and combined impacts on ecosystems in a comprehensive manner. Small-scale forests require an integrated approach to modeling the social and biophysical components comprehensively. Agent-based modeling involves modeling individualistic behavior and interpreting patterns that emerge. The interaction between agents and their environments makes this a valuable tool to assess repeated decisions of individual landowners responding to changing environmental conditions. Agent-based models can be used to determine potential ecological, economic, and social outcomes of landowner decisions and reactions to changing conditions. A forest landowner agent-based model experiment was developed to model timber harvesting in Maine, USA. We present baseline simulation results and compare the effect of a social change (an increased tax rate and a biophysical change (a pest outbreak resulting in increased tree mortality on the system. These three scenarios were analyzed using ANOVA and MANOVA tests on harvested hectares and landowner goal scores to assess landowner behavior and priorities by action. We conclude by reviewing implications for future modeling efforts.

  4. Aquatic insect assemblages associated with subalpine stream segment types in relict glaciated headwaters

    Science.gov (United States)

    Kubo, Joshua S.; Torgersen, Christian E.; Bolton, Susan M.; Weekes, Anne A.; Gara, Robert I.

    2013-01-01

    1. Aquatic habitats and biotic assemblages in subalpine headwaters are sensitive to climate and human impacts. Understanding biotic responses to such perturbations and the contribution of high-elevation headwaters to riverine biodiversity requires the assessment of assemblage composition among habitat types. We compared aquatic insect assemblages among headwater stream segment types in relict glaciated subalpine basins in Mt. Rainier National Park, Washington, USA. 2. Aquatic insects were collected during summer and autumn in three headwater basins. In each basin, three different stream segment types were sampled: colluvial groundwater sources, alluvial lake inlets, and cascade-bedrock lake outlets. Ward's hierarchical cluster analysis revealed high β diversity in aquatic insect assemblages, and non-metric multidimensional scaling indicated that spatial and temporal patterns in assemblage composition differed among headwater stream segment types. Aquatic insect assemblages showed more fidelity to stream segment types than to individual basins, and the principal environmental variables associated with assemblage structure were temperature and substrate. 3. Indicator species analyses identified specific aquatic insects associated with each stream segment type. Several rare and potentially endemic aquatic insect taxa were present, including the recently described species, Lednia borealis (Baumann and Kondratieff). 4. Our results indicate that aquatic insect assemblages in relict glaciated subalpine headwaters were strongly differentiated among stream segment types. These results illustrate the contribution of headwaters to riverine biodiversity and emphasise the importance of these habitats for monitoring biotic responses to climate change. Monitoring biotic assemblages in high-elevation headwaters is needed to prevent the potential loss of unique and sensitive biota.

  5. A fire suppression model for forested range of the Beverly and Qamanirjuaq herds of caribou

    Directory of Open Access Journals (Sweden)

    Donald C. Thomas

    1996-01-01

    Full Text Available A fire suppression model was developed for forested winter range of the Beverly and Qamanirjuaq (formerly Kaminuriak herds of barren-ground caribou (Rangifer tarandus groenlandicus in north-central Canada. The model is a balance between total protection, as voiced by some aboriginal people, and a let-burn policy for natural fires advocated by some ecologists. Elements in the model were caribou ecology, lichen recovery after fire, burn history, community priorities for caribou hunting, and fire cycle lengths. The percent ratio of current productive caribou habitat to the goal for that habitat determines whether fire should be suppressed in a specific area. The goals for productive caribou habitat, defined as forests older than 50 years, were scaled by fire cycle length and community priority ranking. Thus, the model is an example of co-management: traditional knowledge combined with science in a joint forum, the Beverly and Qamanirjuaq Caribou Management Board.

  6. Modeling urban host tree distributions for invasive forest insects using a two-step approach

    Science.gov (United States)

    Mark J. Ambrose; Frank H. Koch; Denys Yemshanov; P. Eric. Wiseman

    2015-01-01

    Many alien insect species currently impacting forested ecosystems in North America first appeared in urban forests. Unfortunately, despite serving as critical gateways for the human-mediated spread of these and other forest pests, urban forests remain less well documented than their “natural” forest counterparts. While Forest Inventory and Analysis (FIA) data provide...

  7. Spatio-temporal modelling of ground vegetation development in mountain spruce forests

    Czech Academy of Sciences Publication Activity Database

    Matějíček, L.; Vávrová, Eva; Cudlín, Pavel

    2011-01-01

    Roč. 222, č. 14 (2011), s. 2584-2592 ISSN 0304-3800 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA MŠk OC10022 Institutional research plan: CEZ:AV0Z60870520 Keywords : Spatio-temporal modelling * Diffusion-reaction model * Ground vegetation * Mountain spruce forest * GIS Subject RIV: EH - Ecology, Behaviour Impact factor: 2.326, year: 2011 http://www.sciencedirect.com/science/article/pii/S0304380010006150

  8. Modelling and predicting the spatial distribution of tree root density in heterogeneous forest ecosystems.

    Science.gov (United States)

    Mao, Zhun; Saint-André, Laurent; Bourrier, Franck; Stokes, Alexia; Cordonnier, Thomas

    2015-08-01

    In mountain ecosystems, predicting root density in three dimensions (3-D) is highly challenging due to the spatial heterogeneity of forest communities. This study presents a simple and semi-mechanistic model, named ChaMRoots, that predicts root interception density (RID, number of roots m(-2)). ChaMRoots hypothesizes that RID at a given point is affected by the presence of roots from surrounding trees forming a polygon shape. The model comprises three sub-models for predicting: (1) the spatial heterogeneity - RID of the finest roots in the top soil layer as a function of tree basal area at breast height, and the distance between the tree and a given point; (2) the diameter spectrum - the distribution of RID as a function of root diameter up to 50 mm thick; and (3) the vertical profile - the distribution of RID as a function of soil depth. The RID data used for fitting in the model were measured in two uneven-aged mountain forest ecosystems in the French Alps. These sites differ in tree density and species composition. In general, the validation of each sub-model indicated that all sub-models of ChaMRoots had good fits. The model achieved a highly satisfactory compromise between the number of aerial input parameters and the fit to the observed data. The semi-mechanistic ChaMRoots model focuses on the spatial distribution of root density at the tree cluster scale, in contrast to the majority of published root models, which function at the level of the individual. Based on easy-to-measure characteristics, simple forest inventory protocols and three sub-models, it achieves a good compromise between the complexity of the case study area and that of the global model structure. ChaMRoots can be easily coupled with spatially explicit individual-based forest dynamics models and thus provides a highly transferable approach for modelling 3-D root spatial distribution in complex forest ecosystems. © The Author 2015. Published by Oxford University Press on behalf of the

  9. OAK FOREST CARBON AND WATER SIMULATIONS: MODEL INTERCOMPARISONS AND EVALUATIONS AGAINST INDEPENDENT DATA

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Paul J [ORNL; Amthor, Jeffrey S [ORNL; Wullschleger, Stan D [ORNL; Wilson, K. [NOAA ATDD; Grant, Robert F. [University of Alberta; Hartley, Anne [Florida International University, Miami; Hui, D. [University of Oklahoma; HuntJr., E. Raymond [USDA ARS; Johnson, Dale W. [University of Nevada, Reno; Kimball, John S. [University of Montana; King, Anthony Wayne [ORNL; Luo, Yiqi [University of Oklahoma; McNulty, Steven G. [USDA Forest Service; Sun, G. [USDA Forest Service; Thornton, Peter [National Center for Atmospheric Research (NCAR); Wang, S. [Canadian Centre for Remote Sensing; Williams, M. [University of Edinburgh; Baldocchi, D. D. [University of California, Berkeley; Cushman, Robert Michael [ORNL

    2004-01-01

    Models represent our primary method for integration of small-scale, processlevel phenomena into a comprehensive description of forest-stand or ecosystem function. They also represent a key method for testing hypotheses about the response of forest ecosystems to multiple changing environmental conditions. This paper describes the evaluation of 13 stand-level models varying in their spatial, mechanistic, and temporal complexity for their ability to capture intra- and interannual components of the water and carbon cycle for an upland, oak-dominated forest of eastern Tennessee. Comparisons between model simulations and observations were conducted for hourly, daily, and annual time steps. Data for the comparisons were obtained from a wide range of methods including: eddy covariance, sapflow, chamber-based soil respiration, biometric estimates of stand-level net primary production and growth, and soil water content by time or frequency domain reflectometry. Response surfaces of carbon and water flux as a function of environmental drivers, and a variety of goodness-of-fit statistics (bias, absolute bias, and model efficiency) were used to judge model performance. A single model did not consistently perform the best at all time steps or for all variables considered. Intermodel comparisons showed good agreement for water cycle fluxes, but considerable disagreement among models for predicted carbon fluxes. The mean of all model outputs, however, was nearly always the best fit to the observations. Not surprisingly, models missing key forest components or processes, such as roots or modeled soil water content, were unable to provide accurate predictions of ecosystem responses to short-term drought phenomenon. Nevertheless, an inability to correctly capture short-term physiological processes under drought was not necessarily an indicator of poor annual water and carbon budget simulations. This is possible because droughts in the subject ecosystem were of short duration and

  10. Specific and generic stem biomass and volume models of tree species in a West African tropical semi-deciduous forest

    DEFF Research Database (Denmark)

    Goussanou, Cédric A.; Guendehou, Sabin; Assogbadjo, Achille E.

    2016-01-01

    The quantification of the contribution of tropical forests to global carbon stocks and climate change mitigation requires availability of data and tools such as allometric equations. This study made available volume and biomass models for eighteen tree species in a semi-deciduous tropical forest...... enabled to conclude that the non-destructive sampling was a good approach to determining reliable basic wood density. The comparative analysis of species-specific models in this study with selected generic models for tropical forests indicated low probability to identify effective generic models with good...

  11. Simulating Urban Growth Using a Random Forest-Cellular Automata (RF-CA Model

    Directory of Open Access Journals (Sweden)

    Courage Kamusoko

    2015-04-01

    Full Text Available Sustainable urban planning and management require reliable land change models, which can be used to improve decision making. The objective of this study was to test a random forest-cellular automata (RF-CA model, which combines random forest (RF and cellular automata (CA models. The Kappa simulation (KSimulation, figure of merit, and components of agreement and disagreement statistics were used to validate the RF-CA model. Furthermore, the RF-CA model was compared with support vector machine cellular automata (SVM-CA and logistic regression cellular automata (LR-CA models. Results show that the RF-CA model outperformed the SVM-CA and LR-CA models. The RF-CA model had a Kappa simulation (KSimulation accuracy of 0.51 (with a figure of merit statistic of 47%, while SVM-CA and LR-CA models had a KSimulation accuracy of 0.39 and −0.22 (with figure of merit statistics of 39% and 6%, respectively. Generally, the RF-CA model was relatively accurate at allocating “non-built-up to built-up” changes as reflected by the correct “non-built-up to built-up” components of agreement of 15%. The performance of the RF-CA model was attributed to the relatively accurate RF transition potential maps. Therefore, this study highlights the potential of the RF-CA model for simulating urban growth.

  12. Remote sensing-based estimation of gross primary production in a subalpine grassland

    Directory of Open Access Journals (Sweden)

    M. Rossini

    2012-07-01

    Full Text Available This study investigates the performances in a terrestrial ecosystem of gross primary production (GPP estimation of a suite of spectral vegetation indexes (VIs that can be computed from currently orbiting platforms. Vegetation indexes were computed from near-surface field spectroscopy measurements collected using an automatic system designed for high temporal frequency acquisition of spectral measurements in the visible near-infrared region. Spectral observations were collected for two consecutive years in Italy in a subalpine grassland equipped with an eddy covariance (EC flux tower that provides continuous measurements of net ecosystem carbon dioxide (CO2 exchange (NEE and the derived GPP.

    Different VIs were calculated based on ESA-MERIS and NASA-MODIS spectral bands and correlated with biophysical (Leaf area index, LAI; fraction of photosynthetically active radiation intercepted by green vegetation, fIPARg, biochemical (chlorophyll concentration and ecophysiological (green light-use efficiency, LUEg canopy variables. In this study, the normalized difference vegetation index (NDVI was the index best correlated with LAI and fIPARg (r = 0.90 and 0.95, respectively, the MERIS terrestrial chlorophyll index (MTCI with leaf chlorophyll content (r = 0.91 and the photochemical reflectance index (PRI551, computed as (R531-R551/(R531+R551 with LUEg (r = 0.64.

    Subsequently, these VIs were used to estimate GPP using different modelling solutions based on Monteith's light-use efficiency model describing the GPP as driven by the photosynthetically active radiation absorbed by green vegetation (APARg and by the efficiency (ε with which plants use the absorbed radiation to fix carbon via photosynthesis. Results show that GPP can be successfully modelled

  13. Fire severity unaffected by spruce beetle outbreak in spruce-fir forests in southwestern Colorado.

    Science.gov (United States)

    Andrus, Robert A; Veblen, Thomas T; Harvey, Brian J; Hart, Sarah J

    2016-04-01

    Recent large and severe outbreaks of native bark beetles have raised concern among the general public and land managers about potential for amplified fire activity in western North America. To date, the majority of studies examining bark beetle outbreaks and subsequent fire severity in the U.S. Rocky Mountains have focused on outbreaks of mountain pine beetle (MPB; Dendroctonus ponderosae) in lodgepole pine (Pinus contorta) forests, but few studies, particularly field studies, have addressed the effects of the severity of spruce beetle (Dendroctonus rufipennis Kirby) infestation on subsequent fire severity in subalpine Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) forests. In Colorado, the annual area infested by spruce beetle outbreaks is rapidly rising, while MPB outbreaks are subsiding; therefore understanding this relationship is of growing importance. We collected extensive field data in subalpine forests in the eastern San Juan Mountains, southwestern Colorado, USA, to investigate whether a gray-stage (forests will alter fire severity, a result that has important implications for management and policy decisions.

  14. Modelling forest carbon stock changes as affected by harvest and natural disturbances. I. Comparison with countries’ estimates for forest management

    Directory of Open Access Journals (Sweden)

    Roberto Pilli

    2016-05-01

    Full Text Available Abstract Background According to the post-2012 rules under the Kyoto protocol, developed countries that are signatories to the protocol have to estimate and report the greenhouse gas (GHG emissions and removals from forest management (FM, with the option to exclude the emissions associated to natural disturbances, following the Intergovernmental Panel on Climate Change (IPCC guidelines. To increase confidence in GHG estimates, the IPCC recommends performing verification activities, i.e. comparing country data with independent estimates. However, countries currently conduct relatively few verification efforts. The aim of this study is to implement a consistent methodological approach using the Carbon Budget Model (CBM to estimate the net CO2 emissions from FM in 26 European Union (EU countries for the period 2000–2012, including the impacts of natural disturbances. We validated our results against a totally independent case study and then we compared the CBM results with the data reported by countries in their 2014 Greenhouse Gas Inventories (GHGIs submitted to the United Nations Framework Convention on Climate Change (UNFCCC. Results The match between the CBM results and the GHGIs was good in nine countries (i.e. the average of our results is within ±25 % compared to the GHGI and the correlation between CBM and GHGI is significant at P < 0.05 and partially good in ten countries. When the comparison was not satisfactory, in most cases we were able to identify possible reasons for these discrepancies, including: (1 a different representation of the interannual variability, e.g. where the GHGIs used the stock-change approach; (2 different assumptions for non-biomass pools, and for CO2 emissions from fires and harvest residues. In few cases, further analysis will be needed to identify any possible inappropriate data used by the CBM or problems in the GHGI. Finally, the frequent updates to data and methods used by countries to prepare GHGI

  15. A Toolkit Modeling Approach for Sustainable Forest Management Planning: Achieving Balance between Science and Local Needs

    Directory of Open Access Journals (Sweden)

    Brian R. Sturtevant

    2007-12-01

    Full Text Available To assist forest managers in balancing an increasing diversity of resource objectives, we developed a toolkit modeling approach for sustainable forest management (SFM. The approach inserts a meta-modeling strategy into a collaborative modeling framework grounded in adaptive management philosophy that facilitates participation among stakeholders, decision makers, and local domain experts in the meta-model building process. The modeling team works iteratively with each of these groups to define essential questions, identify data resources, and then determine whether available tools can be applied or adapted, or whether new tools can be rapidly created to fit the need. The desired goal of the process is a linked series of domain-specific models (tools that balances generalized "top-down" models (i.e., scientific models developed without input from the local system with case-specific customized "bottom-up" models that are driven primarily by local needs. Information flow between models is organized according to vertical (i.e., between scale and horizontal (i.e., within scale dimensions. We illustrate our approach within a 2.1 million hectare forest planning district in central Labrador, a forested landscape where social and ecological values receive a higher priority than economic values. However, the focus of this paper is on the process of how SFM modeling tools and concepts can be rapidly assembled and applied in new locations, balancing efficient transfer of science with adaptation to local needs. We use the Labrador case study to illustrate strengths and challenges uniquely associated with a meta-modeling approach to integrated modeling as it fits within the broader collaborative modeling framework. Principle advantages of the approach include the scientific rigor introduced by peer-reviewed models, combined with the adaptability of meta-modeling. A key challenge is the limited transparency of scientific models to different participatory groups

  16. A comparison of forest canopy models derived from LIDAR and INSAR data in a Pacific Northwest conifer forest.

    Science.gov (United States)

    Hans-Erik Andersen; Robert J. McGaughey; Ward W. Carson; Stephen E. Reutebuch; Bryan Mercer; Jeremy. Allan

    2004-01-01

    Active remote sensing technologies, including interferometric radar (InSAR) and airborne laser scanning (LIDAR) have the potential to provide accurate information relating to three-dimensional forest canopy structure over extensive areas of the landscape. In order to assess the capabilities of these alternative systems for characterizing the forest canopy dimensions,...

  17. Modelling the Response of Energy, Water and CO2 Fluxes Over Forests to Climate Variability

    Science.gov (United States)

    Ju, W.; Chen, J.; Liu, J.; Chen, B.

    2004-05-01

    Understanding the response of energy, water and CO2 fluxes of terrestrial ecosystems to climate variability at various temporal scales is of interest to climate change research. To simulate carbon (C) and water dynamics and their interactions at the continental scale with high temporal and spatial resolutions, the remote sensing driven BEPS (Boreal Ecosystem Productivity Simulator) model was updated to couple with the soil model of CENTURY and a newly developed biophysical model. This coupled model separates the whole canopy into two layers. For the top layer, the leaf-level conductance is scaled up to canopy level using a sunlit and shaded leaf separation approach. Fluxes of water, and CO{2} are simulated as the sums of those from sunlit and shaded leaves separately. This new approach allows for close coupling in modeling these fluxes. The whole profile of soil under a seasonal snowpack is split into four layers for estimating soil moisture and temperature. Long-term means of the vegetation productivity and climate are employed to initialize the carbon pools for the computation of heterotrophic respiration. Validated against tower data at four forested sites, this model is able to describe these fluxes and their response to climate variability. The model captures over 55% of year-round half/one hourly variances of these fluxes. The highest agreement of model results with tower data was achieved for CO2 flux at Southern Old Aspen (SOA) (R2>0.85 and RMSE<2.37 μ mol C m-2 s-1, N=17520). However, the model slightly overestimates the diurnal amplitude of sensible heat flux in winter and sometimes underestimates that of CO2 flux in the growing season. Model simulations suggest that C uptakes of forests are controlled by climate variability and the response of C cycle to climate depends on forest type. For SOA, the annual NPP (Net Primary Productivity) is more sensitive to temperature than to precipitation. This forest usually has higher NPP in warm years than in cool

  18. Transpiration and CO2 fluxes of a pine forest: modelling the undergrowth effect

    Directory of Open Access Journals (Sweden)

    V. Rivalland

    2005-02-01

    Full Text Available A modelling study is performed in order to quantify the relative effect of allowing for the physiological properties of an undergrowth grass sward on total canopy water and carbon fluxes of the Le-Bray forest (Les-Landes, South-western France. The Le-Bray forest consists of maritime pine and an herbaceous undergrowth (purple moor-grass, which is characterised by a low stomatal control of transpiration, in contrast to maritime pine. A CO2-responsive land surface model is used that includes responses of woody and herbaceous species to water stress. An attempt is made to represent the properties of the undergrowth vegetation in the land surface model Interactions between Soil, Biosphere, and Atmosphere, CO2-responsive, ISBA-A-gs. The new adjustment allows for a fairly different environmental response between the forest canopy and the understory in a simple manner. The model's simulations are compared with long term (1997 and 1998 micro-meteorological measurements over the Le-Bray site. The fluxes of energy, water and CO2, are simulated with and without the improved representation of the undergrowth vegetation, and the two simulations are compared with the observations. Accounting for the undergrowth permits one to improve the model's scores. A simple sensitivity experiment shows the behaviour of the model in response to climate change conditions, and the understory effect on the water balance and carbon storage of the forest. Accounting for the distinct characteristics of the undergrowth has a substantial and positive effect on the model accuracy and leads to a different response to climate change scenarios.

  19. Procedural Generation of Large-Scale Forests Using a Graph-Based Neutral Landscape Model

    Directory of Open Access Journals (Sweden)

    Jiaqi Li

    2018-03-01

    Full Text Available Specifying the positions and attributes of plants (e.g., species, size, and height during the procedural generation of large-scale forests in virtual geographic environments is challenging, especially when reflecting the characteristics of vegetation distributions. To address this issue, a novel graph-based neutral landscape model (NLM is proposed to generate forest landscapes with varying compositions and configurations. Our model integrates a set of class-level landscape metrics and generates more realistic and variable landscapes compared with existing NLMs controlled by limited global-level landscape metrics. To produce patches with particular sizes and shapes, a region adjacency graph is transformed from a cluster map that is generated based upon percolation theory; subsequently, optimal neighboring nodes in the graph are merged under restricted growth conditions from a source node. The locations of seeds are randomly placed and their species are classified according to the generated forest landscapes to obtain the final tree distributions. The results demonstrate that our method can generate realistic vegetation distributions representing different spatial patterns of species with a time efficiency that satisfies the requirements for constructing large-scale virtual forests.

  20. Modeling Relationships among 217 Fires Using Remote Sensing of Burn Severity in Southern Pine Forests

    Directory of Open Access Journals (Sweden)

    Amr Abd-Elrahman

    2011-09-01

    Full Text Available Pine flatwoods forests in the southeastern US have experienced severe wildfires over the past few decades, often attributed to fuel load build-up. These forest communities are fire dependent and require regular burning for ecosystem maintenance and health. Although prescribed fire has been used to reduce wildfire risk and maintain ecosystem integrity, managers are still working to reintroduce fire to long unburned areas. Common perception holds that reintroduction of fire in long unburned forests will produce severe fire effects, resulting in a reluctance to prescribe fire without first using expensive mechanical fuels reduction techniques. To inform prioritization and timing of future fire use, we apply remote sensing analysis to examine the set of conditions most likely to result in high burn severity effects, in relation to vegetation, years since the previous fire, and historical fire frequency. We analyze Landsat imagery-based differenced Normalized Burn Ratios (dNBR to model the relationships between previous and future burn severity to better predict areas of potential high severity. Our results show that remote sensing techniques are useful for modeling the relationship between elevated risk of high burn severity and the amount of time between fires, the type of fire (wildfire or prescribed burn, and the historical frequency of fires in pine flatwoods forests.

  1. Modeling N Cycling during Succession after Forest Disturbance: an Analysis of N Mining and Retention Hypothesis

    Science.gov (United States)

    Zhou, Z.; Ollinger, S. V.; Ouimette, A.; Lovett, G. M.; Fuss, C. B.; Goodale, C. L.

    2017-12-01

    Dissolved inorganic nitrogen losses at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA, have declined in recent decades, a pattern that counters expectations based on prevailing theory. An unbalanced ecosystem nitrogen (N) budget implies there is a missing component for N sink. Hypotheses to explain this discrepancy include increasing rates of denitrification and accumulation of N in mineral soil pools following N mining by plants. Here, we conducted a modeling analysis fused with field measurements of N cycling, specifically examining the hypothesis relevant to N mining and retention in mineral soils. We included simplified representations of both mechanisms, N mining and retention, in a revised ecosystem process model, PnET-SOM, to evaluate the dynamics of N cycling during succession after forest disturbance at the HBEF. The predicted N mining during the early succession was regulated by a metric representing a potential demand of extra soil N for large wood growth. The accumulation of nitrate in mineral soil pools was a function of the net aboveground biomass accumulation and soil N availability and parameterized based on field 15N tracer incubation data. The predicted patterns of forest N dynamics were consistent with observations. The addition of the new algorithms also improved the predicted DIN export in stream water with an R squared of 0.35 (Psuccession, and soil retention about 35% at the current forest stage at the HBEF.

  2. Modeling the Influence of Forest Structure on Microsite Habitat Use by Snowshoe Hares

    Directory of Open Access Journals (Sweden)

    Angela K. Fuller

    2013-01-01

    Full Text Available Snowshoe hare (Lepus americanus is an important prey species for many Carnivora and has strong influences on community structure and function in northern forests. An understanding of within-stand (microsite forest structural characteristics that promote high use by hares is important to provide forest management guidelines. We measured forest structural characteristics at the microsite-scale in north-central Maine and used an information-theoretic modeling approach to infer which characteristics were most strongly associated with use by hares during winter. We measured overwinter hare pellet density to model relationships among microsite-scale vegetation structure and hare use. Overwinter pellet density was positively associated with live stem cover (3 × coniferous saplings + deciduous saplings and negatively associated with overstory canopy closure; the two variables explained 71% of the variation in microsite use by hares. The highest pellet densities were in grids with canopy closure 22,000 stems/ha. Silvicultural practices that create dense areas of conifer and deciduous saplings should receive high within-stand use by hares in winter. These conditions can be achieved by promoting the release of advanced regeneration and reducing overstory cover to encourage establishment of shade-intolerant species; clearcutting is one such silvicultural prescription to achieve these conditions.

  3. Modeling the Effects of Harvest Alternatives on Mitigating Oak Decline in a Central Hardwood Forest Landscape.

    Directory of Open Access Journals (Sweden)

    Wen J Wang

    Full Text Available Oak decline is a process induced by complex interactions of predisposing factors, inciting factors, and contributing factors operating at tree, stand, and landscape scales. It has greatly altered species composition and stand structure in affected areas. Thinning, clearcutting, and group selection are widely adopted harvest alternatives for reducing forest vulnerability to oak decline by removing susceptible species and declining trees. However, the long-term, landscape-scale effects of these different harvest alternatives are not well studied because of the limited availability of experimental data. In this study, we applied a forest landscape model in combination with field studies to evaluate the effects of the three harvest alternatives on mitigating oak decline in a Central Hardwood Forest landscape. Results showed that the potential oak decline in high risk sites decreased strongly in the next five decades irrespective of harvest alternatives. This is because oak decline is a natural process and forest succession (e.g., high tree mortality resulting from intense competition would eventually lead to the decrease in oak decline in this area. However, forest harvesting did play a role in mitigating oak decline and the effectiveness varied among the three harvest alternatives. The group selection and clearcutting alternatives were most effective in mitigating oak decline in the short and medium terms, respectively. The long-term effects of the three harvest alternatives on mitigating oak decline became less discernible as the role of succession increased. The thinning alternative had the highest biomass retention over time, followed by the group selection and clearcutting alternatives. The group selection alternative that balanced treatment effects and retaining biomass was the most viable alternative for managing oak decline. Insights from this study may be useful in developing effective and informed forest harvesting plans for managing oak

  4. Modeling the effects of forest harvesting on landscape structure and the spatial distribution of cowbird brood parasitism

    Science.gov (United States)

    Eric J. Gustafson; Thomas R. Crow

    1994-01-01

    Timber harvesting affects both composition and structure of the landscape and has important consequences for organisms using forest habitats. A timber harvest allocation model was constructed that allows the input of specific rules to allocate forest stands for clearcutting to generate landscape patterns reflecting the "look and feel" of managed landscapes....

  5. Maintaining the confidentiality of plot locations by exploiting the low sensitivity of forest structure models to different spectral extraction kernels

    Science.gov (United States)

    Sean P. Healey; Elizabeth Lapoint; Gretchen G. Moisen; Scott L. Powell

    2011-01-01

    The United States Forest Service Forest Inventory and Analysis (FIA) unit maintains a large national network of inventory plots.While the consistency and extent of this network make FIA data attractive for ecological modelling, the FIA is charged by statute not to publicly reveal inventory plot locations. However, use of FIA plot data by the remote sensing community...

  6. Influence of forest roads standards and networks on water yield as predicted by the distributed hydrology-soil-vegetation model

    Science.gov (United States)

    Salli F. Dymond; W. Michael Aust; Steven P. Prisley; Mark H. Eisenbies; James M. Vose

    2013-01-01

    Throughout the country, foresters are continually looking at the effects of logging and forest roads on stream discharge and overall stream health. In the Pacific Northwest, a distributed hydrology-soil-vegetation model (DHSVM) has been used to predict the effects of logging on peak discharge in mountainous regions. DHSVM uses elevation, meteorological, vegetation, and...

  7. Predicting surface fuel models and fuel metrics using lidar and CIR imagery in a dense mixed conifer forest

    Science.gov (United States)

    Marek K. Jakubowksi; Qinghua Guo; Brandon Collins; Scott Stephens; Maggi. Kelly

    2013-01-01

    We compared the ability of several classification and regression algorithms to predict forest stand structure metrics and standard surface fuel models. Our study area spans a dense, topographically complex Sierra Nevada mixed-conifer forest. We used clustering, regression trees, and support vector machine algorithms to analyze high density (average 9 pulses/m

  8. Quantifying the Model-Related Variability of Biomass Stock and Change Estimates in the Norwegian National Forest Inventory

    Science.gov (United States)

    Johannes Breidenbach; Clara Antón-Fernández; Hans Petersson; Ronald E. McRoberts; Rasmus Astrup

    2014-01-01

    National Forest Inventories (NFIs) provide estimates of forest parameters for national and regional scales. Many key variables of interest, such as biomass and timber volume, cannot be measured directly in the field. Instead, models are used to predict those variables from measurements of other field variables. Therefore, the uncertainty or variability of NFI estimates...

  9. 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.

  10. Model for absorption and release of gaseous materials by forest canopies

    International Nuclear Information System (INIS)

    Murphy, C.E. Jr.

    1976-01-01

    A model of the physical processes defining the absorption and release of materials by a forest canopy has been developed. The model deals with the turbulent transport of gaseous materials in the surface boundary layer near the canopy, the turbulent transport in the canopy atmosphere, the transport through the boundary layer near the leaf and soil surface, and the solution of the gaseous materials in intracellular fluids and subsequent diffusion into the leaf cells. The model is used to simulate the uptake of molecular tritium by the forest canopy and the subsequent release of tritiated water. Results of dynamic simulations of tritium uptake and release are compared with data collected at the time of a release of molecular tritium to the atmosphere

  11. Linear compartment model of plutonium dynamics in a deciduous forest ecosystem

    International Nuclear Information System (INIS)

    Garten, C.T. Jr.; Gardner, R.H.; Dahlman, R.C.

    1977-01-01

    Systems ecology techniques have been useful in simulating the fate and dynamics of radionuclides in forest ecosystems. The applications of systems models in this context are twofold: projection of the time-dependent distribution of radioisotopes among various ecosystems components, and manipulation of the modeled system to determine the sensitivity of components to variation in transfer coefficients and, thereby, identify critical fluxes affecting system behavior. The present paper describes a systems model that projects the possible fate of plutonium in a deciduous forest ecosystem. The isotopes of interest are 239 Pu and 240 Pu which have physical half lives of 2.44 x 10 4 and 6540 years, respectively. These isotopes are indistinguishable by alpha spectrometry hence 239 Pu is used to refer to both

  12. Increased drought impacts on temperate rainforests from southern South America: results of a process-based, dynamic forest model.

    Science.gov (United States)

    Gutiérrez, Alvaro G; Armesto, Juan J; Díaz, M Francisca; Huth, Andreas

    2014-01-01

    Increased droughts due to regional shifts in temperature and rainfall regimes are likely to affect forests in temperate regions in the coming decades. To assess their consequences for forest dynamics, we need predictive tools that couple hydrologic processes, soil moisture dynamics and plant productivity. Here, we developed and tested a dynamic forest model that predicts the hydrologic balance of North Patagonian rainforests on Chiloé Island, in temperate South America (42°S). The model incorporates the dynamic linkages between changing rainfall regimes, soil moisture and individual tree growth. Declining rainfall, as predicted for the study area, should mean up to 50% less summer rain by year 2100. We analysed forest responses to increased drought using the model proposed focusing on changes in evapotranspiration, soil moisture and forest structure (above-ground biomass and basal area). We compared the responses of a young stand (YS, ca. 60 years-old) and an old-growth forest (OG, >500 years-old) in the same area. Based on detailed field measurements of water fluxes, the model provides a reliable account of the hydrologic balance of these evergreen, broad-leaved rainforests. We found higher evapotranspiration in OG than YS under current climate. Increasing drought predicted for this century can reduce evapotranspiration by 15% in the OG compared to current values. Drier climate will alter forest structure, leading to decreases in above ground biomass by 27% of the current value in OG. The model presented here can be used to assess the potential impacts of climate change on forest hydrology and other threats of global change on future forests such as fragmentation, introduction of exotic tree species, and changes in fire regimes. Our study expands the applicability of forest dynamics models in remote and hitherto overlooked regions of the world, such as southern temperate rainforests.

  13. Increased drought impacts on temperate rainforests from southern South America: results of a process-based, dynamic forest model.

    Directory of Open Access Journals (Sweden)

    Alvaro G Gutiérrez

    Full Text Available Increased droughts due to regional shifts in temperature and rainfall regimes are likely to affect forests in temperate regions in the coming decades. To assess their consequences for forest dynamics, we need predictive tools that couple hydrologic processes, soil moisture dynamics and plant productivity. Here, we developed and tested a dynamic forest model that predicts the hydrologic balance of North Patagonian rainforests on Chiloé Island, in temperate South America (42°S. The model incorporates the dynamic linkages between changing rainfall regimes, soil moisture and individual tree growth. Declining rainfall, as predicted for the study area, should mean up to 50% less summer rain by year 2100. We analysed forest responses to increased drought using the model proposed focusing on changes in evapotranspiration, soil moisture and forest structure (above-ground biomass and basal area. We compared the responses of a young stand (YS, ca. 60 years-old and an old-growth forest (OG, >500 years-old in the same area. Based on detailed field measurements of water fluxes, the model provides a reliable account of the hydrologic balance of these evergreen, broad-leaved rainforests. We found higher evapotranspiration in OG than YS under current climate. Increasing drought predicted for this century can reduce evapotranspiration by 15% in the OG compared to current values. Drier climate will alter forest structure, leading to decreases in above ground biomass by 27% of the current value in OG. The model presented here can be used to assess the potential impacts of climate change on forest hydrology and other threats of global change on future forests such as fragmentation, introduction of exotic tree species, and changes in fire regimes. Our study expands the applicability of forest dynamics models in remote and hitherto overlooked regions of the world, such as southern temperate rainforests.

  14. Spatial modeling of fires: a predictive tool for La Primavera Forest, Jalisco Mexico

    Directory of Open Access Journals (Sweden)

    Jose Luis Ibarra-Montoya

    2016-03-01

    Full Text Available The interaction of various elements of socioeconomic, political and cultural nature, influenced by landscape and climatic factors, are important aspects of fire regimes. Space models that integrate these elements and factors help to more accurately predict potential fire areas. The Protected Area Wildlife La Primavera (APFFLP is the main regulator of the climate of the Guadalajara metropolitan area, and forest fires frequently occur there. These represent a challenge for science and technology to develop methodologies that help predict forest fires. This study involves the construction of a spatial model that helps identify potential areas of fire in that area. The model integrates meteorological variables, landscape, fuels, anthropogenic and / or causality, and historical occurrences of fires during the period 1998-2012. According to the model, the variables that determine the areas of greatest fire potential are: slope (landscape, relative humidity (weather, vegetation type (causality and land use (anthropogenic. The model predicts a large area with high potential for fire, located in the central and northwest APFFLP polygon; also, there are small, isolated potential zones in the eastern part of the polygon. The information developed by this study could support the generation of local risk maps, thereby optimizing the actions of fire management and restoration of the La Primavera forest.

  15. Development of the BIOME-BGC model for the simulation of managed Moso bamboo forest ecosystems.

    Science.gov (United States)

    Mao, Fangjie; Li, Pingheng; Zhou, Guomo; Du, Huaqiang; Xu, Xiaojun; Shi, Yongjun; Mo, Lufeng; Zhou, Yufeng; Tu, Guoqing

    2016-05-01

    Numerical models are the most appropriate instrument for the analysis of the carbon balance of terrestrial ecosystems and their interactions with changing environmental conditions. The process-based model BIOME-BGC is widely used in simulation of carbon balance within vegetation, litter and soil of unmanaged ecosystems. For Moso bamboo forests, however, simulations with BIOME-BGC are inaccurate in terms of the growing season and the carbon allocation, due to the oversimplified representation of phenology. Our aim was to improve the applicability of BIOME-BGC for managed Moso bamboo forest ecosystem by implementing several new modules, including phenology, carbon allocation, and management. Instead of the simple phenology and carbon allocation representations in the original version, a periodic Moso bamboo phenology and carbon allocation module was implemented, which can handle the processes of Moso bamboo shooting and high growth during "on-year" and "off-year". Four management modules (digging bamboo shoots, selective cutting, obtruncation, fertilization) were integrated in order to quantify the functioning of managed ecosystems. The improved model was calibrated and validated using eddy covariance measurement data collected at a managed Moso bamboo forest site (Anji) during 2011-2013 years. As a result of these developments and calibrations, the performance of the model was substantially improved. Regarding the measured and modeled fluxes (gross primary production, total ecosystem respiration, net ecosystem exchange), relative errors were decreased by 42.23%, 103.02% and 18.67%, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Modeling the height of young forests regenerating from recent disturbances in Mississippi using Landsat and ICESat data

    Science.gov (United States)

    Li, Ainong; Huang, Chengquan; Sun, Guoqing; Shi, Hua; Toney, Chris; Zhu, Zhiliang; Rollins, Matthew G.; Goward, Samuel N.; Masek, Jeffery G.

    2011-01-01

    Many forestry and earth science applications require spatially detailed forest height data sets. Among the various remote sensing technologies, lidar offers the most potential for obtaining reliable height measurement. However, existing and planned spaceborne lidar systems do not have the capability to produce spatially contiguous, fine resolution forest height maps over large areas. This paper describes a Landsat–lidar fusion approach for modeling the height of young forests by integrating historical Landsat observations with lidar data acquired by the Geoscience Laser Altimeter System (GLAS) instrument onboard the Ice, Cloud, and land Elevation (ICESat) satellite. In this approach, “young” forests refer to forests reestablished following recent disturbances mapped using Landsat time-series stacks (LTSS) and a vegetation change tracker (VCT) algorithm. The GLAS lidar data is used to retrieve forest height at sample locations represented by the footprints of the lidar data. These samples are used to establish relationships between lidar-based forest height measurements and LTSS–VCT disturbance products. The height of “young” forest is then mapped based on the derived relationships and the LTSS–VCT disturbance products. This approach was developed and tested over the state of Mississippi. Of the various models evaluated, a regression tree model predicting forest height from age since disturbance and three cumulative indices produced by the LTSS–VCT method yielded the lowest cross validation error. The R2 and root mean square difference (RMSD) between predicted and GLAS-based height measurements were 0.91 and 1.97 m, respectively. Predictions of this model had much higher errors than indicated by cross validation analysis when evaluated using field plot data collected through the Forest Inventory and Analysis Program of USDA Forest Service. Much of these errors were due to a lack of separation between stand clearing and non-stand clearing

  17. Analytical approach to ecophysiological forest modeling. Computer reference-information system

    International Nuclear Information System (INIS)

    Berezovskaya, F.S.; Karev, G.P.

    1994-11-01

    A great attention is directed now to problems associated with analysis and classification of the mathematical modeling methods to be applied for studying the structure and dynamics of plant (especially forest) communities, for accounting and planning of forestry activities, as well as for monitoring efforts. Among numerous models of plant objects and plant communities that differ in modeling purpose, as well as in the mechanisms and ways of description, in this paper has been selected a class of the so-called 'ecophysiological', or 'explaining', models, i.e. those involving, as variables, values with a direct ecophysiological interpretation. 69 refs

  18. Handbook on advances in remote sensing and geographic information systems paradigms and applications in forest landscape modeling

    CERN Document Server

    Favorskaya, Margarita N

    2017-01-01

    This book presents the latest advances in remote-sensing and geographic information systems and applications. It is divided into four parts, focusing on Airborne Light Detection and Ranging (LiDAR) and Optical Measurements of Forests; Individual Tree Modelling; Landscape Scene Modelling; and Forest Eco-system Modelling. Given the scope of its coverage, the book offers a valuable resource for students, researchers, practitioners, and educators interested in remote sensing and geographic information systems and applications.

  19. Fitting a Two-Component Scattering Model to Polarimetric SAR Data from Forests

    Science.gov (United States)

    Freeman, Anthony

    2007-01-01

    Two simple scattering mechanisms are fitted to polarimetric synthetic aperture radar (SAR) observations of forests. The mechanisms are canopy scatter from a reciprocal medium with azimuthal symmetry and a ground scatter term that can represent double-bounce scatter from a pair of orthogonal surfaces with different dielectric constants or Bragg scatter from a modera