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Eric S Kasischke - One of the best experts on this subject based on the ideXlab platform.
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modeling the effects of Fire Severity and climate warming on active layer thickness and soil carbon storage of black spruce forests across the landscape in interior alaska
Environmental Research Letters, 2013Co-Authors: Helene Genet, Eric S Kasischke, A D Mcguire, Kirsten Barrett, A L Breen, Eugenie S Euskirchen, Jill F Johnstone, A M Melvin, A Bennett, Michelle C. MackAbstract:There is a substantial amount of carbon stored in the permafrost soils of boreal forest ecosystems, where it is currently protected from decomposition. The surface organic horizons insulate the deeper soil from variations in atmospheric temperature. The removal of these insulating horizons through consumption by Fire increases the vulnerability of permafrost to thaw, and the carbon stored in permafrost to decomposition. In this study we ask how warming and Fire regime may influence spatial and temporal changes in active layer and carbon dynamics across a boreal forest landscape in interior Alaska. To address this question, we (1) developed and tested a predictive model of the effect of Fire Severity on soil organic horizons that depends on landscape-level conditions and (2) used this model to evaluate the long-term consequences of warming and changes in Fire regime on active layer and soil carbon dynamics of black spruce forests across interior Alaska. The predictive model of Fire Severity, designed from the analysis of field observations, reproduces the effect of local topography (landform category, the slope angle and aspect and flow accumulation), weather conditions (drought index, soil moisture) and Fire characteristics (day of year and size of the Fire) on the reduction of the organic layer
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evaluating the potential of landsat tm etm imagery for assessing Fire Severity in alaskan black spruce forests
International Journal of Wildland Fire, 2008Co-Authors: Elizabeth E Hoy, Simon N Trigg, Nancy H F French, Merritt R Turetsky, Eric S KasischkeAbstract:Satellite remotely sensed data of Fire disturbance offers important information; however, current methods to study Fire Severity may need modifications for boreal regions. We assessed the potential of the differenced Normalized Burn Ratio (dNBR) and other spectroscopic indices and image transforms derived from Landsat TM/ETM+ data for mapping Fire Severity in Alaskan black spruce forests (Picea mariana) using ground measures of Severity from 55 plots located in two Fire events. The analysis yielded low correlations between the satellite and field measures of Severity, with the highest correlation (R 2 = 0.52, P < 0.0001) between the dNBR and the composite burn index being lower than those found in similar studies in forests in the conterminous USA. Correlations improved using a ratio of two Landsat shortwave infrared bands (Band 7/Band 5). Overall, the satellite Fire Severity indices and transformations were more highly correlated with measures of canopy-layer Fire Severity than ground-layer Fire Severity. High levels of Fire Severity present in the Fire events, deep organic soils, varied topography of the boreal region, and variations in solar elevation angle may account for the low correlations, and illustrate the challenges faced in developing approaches to map Fire and burn Severity in high northern latitude regions.
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evaluation of the composite burn index for assessing Fire Severity in alaskan black spruce forests
International Journal of Wildland Fire, 2008Co-Authors: Eric S Kasischke, Elizabeth E Hoy, Nancy H F French, Merritt R Turetsky, Roger D Ottmar, Evan S KaneAbstract:We evaluated the utility of the composite burn index (CBI) for estimating Fire Severity in Alaskan black spruce forests by comparing data from 81 plots located in 2004 and 2005 Fire events. We collected data to estimate the CBI and quantify crown damage, percent of trees standing after the Fire, depth of the organic layer remaining after the Fire, depth of burning in the surface organic layer (absolute and relative), and the substrate layer exposed by the Fire. To estimate pre-Fire organic layer depth, we collected data in 15 unburned stands to develop relationships between total organic layer depth and measures of the adventitious root depth above mineral soil and below the surface of the organic layer. We validated this algorithm using data collected in 17 burned stands where pre-Fire organic layer depth had been measured. The average total CBI value in the black spruce stands was 2.46, with most of the variation a result of differences in the CBI observed for the substrate layer. While a quadratic equation using the substrate component of CBI was a relatively strong predictor of mineral soil exposure as a result of Fire (R 2 = 0.61, P < 0.0001, F = 60.3), low correlations were found between the other measures of Fire Severity and the CBI (R 2 = 0.00-0.37). These results indicate that the CBI approach has limited potential for quantifying Fire Severity in these ecosystems, in particular organic layer consumption, which is an important factor to understand how ecosystems will respond to changing climate and Fire regimes in northern regions.
Monica G Turner - One of the best experts on this subject based on the ideXlab platform.
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Fire Severity and tree regeneration following bark beetle outbreaks the role of outbreak stage and burning conditions
Ecological Applications, 2014Co-Authors: Brian J Harvey, Daniel C Donato, William H Romme, Monica G TurnerAbstract:The degree to which recent bark beetle (Dendroctonus ponderosae) outbreaks may influence Fire Severity and postFire tree regeneration is of heightened interest to resource managers throughout western North America, but empirical data on actual Fire effects are lacking. Outcomes may depend on burning conditions (i.e., weather during Fire), outbreak Severity, or intervals between outbreaks and subsequent Fire. We studied recent Fires that burned through green-attack/red-stage (outbreaks <3 years before Fire) and gray-stage (outbreaks 3–15 years before Fire) subalpine forests dominated by lodgepole pine (Pinus contorta var. latifolia) in Greater Yellowstone, Wyoming, USA, to determine if Fire Severity was linked to preFire beetle outbreak Severity and whether these two disturbances produced compound ecological effects on postFire tree regeneration. With field data from 143 postFire plots that burned under different conditions, we assessed canopy and surface Fire Severity, and postFire tree seedling density a...
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influence of recent bark beetle outbreak on Fire Severity and postFire tree regeneration in montane douglas fir forests
Ecology, 2013Co-Authors: Brian J Harvey, Daniel C Donato, William H Romme, Monica G TurnerAbstract:Understanding how disturbances interact to shape ecosystems is a key challenge in ecology. In forests of western North America, the degree to which recent bark beetle outbreaks and subsequent Fires may be linked (e.g., outbreak Severity affects Fire Severity) and/ or whether these two disturbances produce compound effects on postFire succession is of widespread interest. These interactions remain unresolved, largely because field data from actual wildFires following beetle outbreaks are lacking. We studied the 2008 Gunbarrel Fire, which burned 27 200 ha in Douglas-fir (Pseudotsuga menziesii ) forests that experienced a bark beetle outbreak 4-13 years preFire (''gray stage,'' after trees have died and needles have dropped), to determine whether outbreak Severity influenced subsequent Fire Severity and postFire tree regeneration. In 85 sample plots we recorded preFire stand structure and outbreak Severity; multiple measures of canopy and forest-floor Fire Severity; and postFire tree seedling density. PreFire outbreak Severity was not related to any measure of Fire Severity except for mean bole scorch, which declined slightly with increasing outbreak Severity. Instead, Fire Severity varied with topography and burning conditions (proxy for weather at time of Fire). PostFire Douglas-fir regeneration was low, with tree seedlings absent in 65% of plots. Tree seedlings were abundant in plots of low Fire Severity that also had experienced low outbreak Severity (mean ¼ 1690 seedlings/ha), suggesting a dual filter on tree regeneration. Although bark beetles and Fire collectively reduced live basal area to ,5% and increased snag density to .2000% of pre-outbreak levels, the lack of relationship between beetle outbreak and Fire Severity suggests that these disturbances were not linked. Nonetheless, effects on postFire tree regeneration suggest compound disturbance interactions that contribute to the structural heterogeneity characteristic of mid/lower montane forests.
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preFire heterogeneity Fire Severity and early postFire plant reestablishment in subalpine forests of yellowstone national park wyoming
International Journal of Wildland Fire, 1999Co-Authors: Monica G Turner, William H Romme, Robert H GardnerAbstract:The 1988 Fires in Yellowstone National Park providedan opportunity to study effects of a large infrequent disturbance on a natural community. This study addressed two questions: (1) How does preFire heterogeneity of the landscape affect postFire patterns of Fire Severity? and (2) How do postFire patterns of burn Severity influence plant reestablishment? At three sites, 100 sampling points were distributed regularly in a 1-km x 1-km grid and sampled annually from 1989 to 1992. Information was recorded on Fire Severity (damage to trees, depth of ash and soil charring, and percent mineral soil exposed); pre-Fire forest structure (forest successional stage; tree density; tree species; tree size; and evidence of pre-Fire disturbance by mountain pine beetle [Dendroctonus ponderosae Hopk.] or mistletoe [Arceuthobium americanum Nutt. ex Engelm.]); post-Fire percent cover of graminoids, forbs, and low shrubs; number of lodgepole pine (Pinus contorta var. latifolia Engelm.) seedlings; and general topographic characteristics (slope and aspect). Fire Severity was influenced by successional stage, with older stands more likely to be in the more severe burn class, and by tree diameter, with tree damage diminishing with tree size. PreFire bark beetle and mistletoe damage also influenced Fire Severity; severe preFire damage increased the likelihood of crown Fire, but intermediate preFire damage reduced the likelihood of crown Fire. Fire Severity was not influenced by slope, aspect, or tree density. PostFire percent vegetative cover and density of lodgepole pine seedlings varied with burn Severity. In lightly burned areas, percent cover returned to unburned levels by 1991. In severely burned areas, total percent cover was about half that of unburned areas by 1992, and shrub cover remained reduced. Recruitment of lodgepole pine seedlings was greatest during the second postFire year and in severe-surface burns rather than in crown Fires. Continued monitoring of vegetation dynamics in Yellowstone’s burned forests will contribute to our understanding of successional processes following a disturbance that was exceptional in its size and Severity.
Jessica R Miesel - One of the best experts on this subject based on the ideXlab platform.
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Fire Severity alters the distribution of pyrogenic carbon stocks across ecosystem pools in a californian mixed conifer forest
Journal of Geophysical Research, 2017Co-Authors: Bernardo Maestrini, Hugh D. Safford, Erin C Alvey, Matthew D Hurteau, Jessica R MieselAbstract:Pyrogenic carbon (PyC) is hypothesized to play an important role in the carbon (C) cycle due to its resistance to decomposition; however, much uncertainty still exists regarding the stocks of PyC that persist on-site after the initial erosion in post-Fire forests. Therefore, understanding how Fire characteristics influence PyC stocks is vital, particularly in the context of California forests for which an increase of high-Severity Fires is predicted over the next decades. We measured forest C and persistent PyC stocks in areas burned by low-to-moderate and high-Severity Fire, as well as in adjacent unburned areas in a California mixed-conifer forest, two to three years after wildFire. We measured C and PyC stocks in the following compartments: standing trees, downed wood, forest floor and mineral soil (0–5 cm), and we identified PyC using the weak nitric acid digestion method. We found that the total stock of PyC did not differ among Fire Severity classes (overall mean 248 ± 30 g C m−2); however, Fire Severity influenced the distribution of PyC in the individual compartments. Areas burned by high-Severity Fire had 2.5 times more PyC stocked in the coarse woody debris (p < 0.05), 3.3 times more PyC stocked in standing trees (p < 0.05) and a lower PyC stock in the forest floor (−22%, p < 0.05) compared to low-to-moderate Fire Severity areas. These results have important implications for the permanence time of PyC, which is putatively higher in standing trees and coarse woody debris compared to the forest floor, where it is susceptible to rapid losses through erosion.
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emissions of forest floor and mineral soil carbon nitrogen and mercury pools and relationships with Fire Severity for the pagami creek Fire in the boreal forest of northern minnesota
International Journal of Wildland Fire, 2017Co-Authors: Randy Kolka, Shawn Fraver, Brian R Sturtevant, Jessica R Miesel, Peter T Wolter, Thomas M Desutter, Aditya Singh, Phil TownsendAbstract:Forest Fires cause large emissions of C (carbon), N (nitrogen) and Hg (mercury) to the atmosphere and thus have important implications for global warming (e.g. via CO2 and N2O emissions), anthropogenic fertilisation of natural ecosystems (e.g. via N deposition), and bioaccumulation of harmful metals in aquatic and terrestrial systems (e.g. via Hg deposition). Research indicates that Fires are becoming more severe over much of North America, thus increasing element emissions during Fire. However, there has been little research relating forest floor and mineral soil losses of C, N and Hg to on-the-ground indices of Fire Severity that enable scaling up those losses for larger-scale accounting of Fire-level emissions. We investigated the relationships between forest floor and mineral soil elemental pools across a range of soil-level Fire severities following the 2011 Pagami Creek wildFire in northern Minnesota, USA. We were able to statistically differentiate losses of forest floor C, N and Hg among a five-class soil-level Fire Severity classification system. Regression relationships using soil Fire Severity class were able to predict remaining forest floor C, N and Hg pools with 82–96% confidence. We correlated National Aeronautics and Space Administration Airborne Visible and Infrared Imaging Spectrometer-Classic imagery to ground-based plot-scale estimates of soil Fire Severity to upscale emissions of C, N and Hg to the Fire level. We estimate that 468 000 Mg C, 11 000 Mg of N and over 122 g of Hg were emitted from the forest floor during the burning of the 28 310 ha upland area of the Pagami Creek Fire.
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soil organic matter composition and quality across Fire Severity gradients in coniferous and deciduous forests of the southern boreal region
Journal of Geophysical Research, 2015Co-Authors: Jessica R Miesel, Randy Kolka, William C Hockaday, Philip A TownsendAbstract:Recent patterns of prolonged regional drought in southern boreal forests of the Great Lakes region, USA, suggest that the ecological effects of disturbance by wildFire may become increasingly severe. Losses of forest soil organic matter (SOM) during Fire can limit soil nutrient availability and forest regeneration. These processes are also influenced by the composition of postFire SOM. We sampled the forest floor layer (i.e., full organic horizon) and 0–10 cm mineral soil from stands dominated by coniferous (Pinus banksiana Lamb.) or deciduous (Populus tremuloides Michx.) species 1–2 months after the 2011 Pagami Creek wildFire in northern Minnesota. We used solid-state 13C NMR to characterize SOM composition across a gradient of Fire Severity in both forest cover types. SOM composition was affected by Fire, even when no statistically significant losses of total C stocks were evident. The most pronounced differences in SOM composition between burned and unburned reference areas occurred in the forest floor for both cover types. Carbohydrate stocks in forest floor and mineral horizons decreased with Severity level in both cover types, whereas pyrogenic C stocks increased with Severity in the coniferous forest floor and decreased in only the highest Severity level in the deciduous forest floor. Loss of carbohydrate and lignin pools contributed to a decreased SOM stability index and increased decomposition index. Our results suggest that increases in Fire Severity expected to occur under future climate scenarios may lead to changes in SOM composition and dynamics with consequences for postFire forest recovery and C uptake.
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post Fire comparisons of forest floor and soil carbon nitrogen and mercury pools with Fire Severity indices
Soil Science Society of America Journal, 2014Co-Authors: Randy Kolka, Shawn Fraver, Brian R Sturtevant, Philip A Townsend, Jessica R Miesel, Peter T Wolter, Thomas M DesutterAbstract:Forest Fires are important contributors of C, N, and Hg to the atmosphere. In the fall of 2011, a large wildFire occurred in northern Minnesota and we were able to quickly access the area to sample the forest floor and mineral soil for C, N, and Hg pools. When compared with unburned reference soils, the mean loss of C resulting from Fire in the forest floor and the upper 20 cm of mineral soil was 19.3 Mg ha-1, for N the mean loss was 0.17 Mg ha-1, and for Hg the mean loss was 9.3 g ha-1. To assess the influence of Fire Severity on the forest floor and mineral soils, we used an established method that included a soil burn Severity index and a tree burn Severity index with a gradient of Severity classes. It was apparent that the unburned reference class had greater forest floor C, N, and Hg pools and higher C/N ratios than the burned classes. The C/N ratios of the 0- to 10- and 10- to 20-cm mineral soils in the unburned reference class were also greater than in the burned classes, indicating that a small amount of C was lost and/or N was gained, potentially through leaching unburned forest floor material. However, with a couple of exceptions, the Severity classes were unable to differentiate the forest floor and mineral soil impacts among soil burn and tree burn Severity indices. Developing burn Severity indices that are reflective of soil elemental impacts is an important first step in scaling ecosystem impacts both within and across Fire events.
Carla M Dantonio - One of the best experts on this subject based on the ideXlab platform.
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effects of Fire Severity and post Fire climate on short term vegetation recovery of mixed conifer and red fir forests in the sierra nevada mountains of california
Remote Sensing of Environment, 2015Co-Authors: Ran Meng, Philip E Dennison, Chengquan Huang, Max A Moritz, Carla M DantonioAbstract:Abstract Forest ecosystems in the Sierra Nevada Mountains of California are greatly influenced by wildFire as a natural disturbance, and increased Fire Severity and drought occurrence may alter the course of post-Fire recovery in these ecosystems. We examined effects of Fire Severity, post-Fire climate, and topographic factors on short-term ( 405 ha) between 1999 and 2006 were examined. According to the modeling results provided by ordinary least squares (OLS) regressions including spatial variation coefficients, Fire Severity, post-Fire wet eason precipitation, post-Fire January minimum temperature, and topographic factors explain variations in short-term post-Fire NDVI values (adjusted R-squared = [0.680, 0.688] for red fir forests; adjusted R-squared = [0.671, 0.678] for mixed-conifer forests). The modeling results indicated that burned mixed-conifer forest was sensitive to post-Fire drought, while burned red fir forest, with higher summer soil moisture availability, was sensitive to post-Fire temperature. We also found that differences in recovery related to Fire Severity disappeared more quickly in burned mixed-conifer forest than in burned red fir forest. Future efforts should focus on long-term recovery, including competition between forest and shrub species in previously burned areas.
Simon N Trigg - One of the best experts on this subject based on the ideXlab platform.
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evaluating the potential of landsat tm etm imagery for assessing Fire Severity in alaskan black spruce forests
International Journal of Wildland Fire, 2008Co-Authors: Elizabeth E Hoy, Simon N Trigg, Nancy H F French, Merritt R Turetsky, Eric S KasischkeAbstract:Satellite remotely sensed data of Fire disturbance offers important information; however, current methods to study Fire Severity may need modifications for boreal regions. We assessed the potential of the differenced Normalized Burn Ratio (dNBR) and other spectroscopic indices and image transforms derived from Landsat TM/ETM+ data for mapping Fire Severity in Alaskan black spruce forests (Picea mariana) using ground measures of Severity from 55 plots located in two Fire events. The analysis yielded low correlations between the satellite and field measures of Severity, with the highest correlation (R 2 = 0.52, P < 0.0001) between the dNBR and the composite burn index being lower than those found in similar studies in forests in the conterminous USA. Correlations improved using a ratio of two Landsat shortwave infrared bands (Band 7/Band 5). Overall, the satellite Fire Severity indices and transformations were more highly correlated with measures of canopy-layer Fire Severity than ground-layer Fire Severity. High levels of Fire Severity present in the Fire events, deep organic soils, varied topography of the boreal region, and variations in solar elevation angle may account for the low correlations, and illustrate the challenges faced in developing approaches to map Fire and burn Severity in high northern latitude regions.
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remote sensing of Fire Severity assessing the performance of the normalized burn ratio
IEEE Geoscience and Remote Sensing Letters, 2006Co-Authors: David P Roy, Luigi Boschetti, Simon N TriggAbstract:Several studies have used satellite data to map different levels of Fire Severity present within burned areas. Increasingly, Fire Severity has been estimated using a spectral index called the normalized burn ratio (NBR). This letter assesses the performance of the NBR against ideal requirements of a spectral index designed to measure Fire Severity. According to index theory, the NBR would be optimal for quantifying Fire Severity if the trajectory in spectral feature space caused by different levels of Severity occurred perpendicular to the NBR isolines. We assess how well NBR meets this condition using reflectance data sensed before and shortly after Fires in the South African savanna, Australian savanna, Russian Federation boreal forest, and South American tropical forest. Although previous studies report high correlation between Fire Severity measured in the field- and satellite-derived NBR, our results do not provide evidence that the performance of the NBR is optimal in describing Fire Severity shortly after Fire occurrence. Spectral displacements due to burning occur in numerous directions relative to the NBR index isolines, suggesting that the NBR may not be primarily and consistently sensitive to Fire Severity. Findings suggest that the development of the next generation of methods to estimate Fire Severity remotely should incorporate knowledge of how Fires of different Severity displace the position of preFire vegetation in multispectral space.