Prioritizing forest fuels treatments based on the probability of high-severity fire restores adaptive capacity in Sierran forests

Treesearch

Daniel J. Krofcheck; Matthew D. Hurteau; Robert M. Scheller; E. Louise Loudermilk

2017-01-01

In frequent fire forests of the western United States, a legacy of fire suppression coupled with increases in fire weather severity have altered fire regimes and vegetation dynamics. When coupled with projected climate change, these conditions have the potential to lead to vegetation type change and altered carbon (C) dynamics. In the Sierra Nevada, fuels...

Post-fire vegetation and fuel development influences fire severity patterns in reburns.

PubMed

Coppoletta, Michelle; Merriam, Kyle E; Collins, Brandon M

2016-04-01

In areas where fire regimes and forest structure have been dramatically altered, there is increasing concern that contemporary fires have the potential to set forests on a positive feedback trajectory with successive reburns, one in which extensive stand-replacing fire could promote more stand-replacing fire. Our study utilized an extensive set of field plots established following four fires that occurred between 2000 and 2010 in the northern Sierra Nevada, California, USA that were subsequently reburned in 2012. The information obtained from these field plots allowed for a unique set of analyses investigating the effect of vegetation, fuels, topography, fire weather, and forest management on reburn severity. We also examined the influence of initial fire severity and time since initial fire on influential predictors of reburn severity. Our results suggest that high- to moderate-severity fire in the initial fires led to an increase in standing snags and shrub vegetation, which in combination with severe fire weather promoted high-severity fire effects in the subsequent reburn. Although fire behavior is largely driven by weather, our study demonstrates that post-fire vegetation composition and structure are also important drivers of reburn severity. In the face of changing climatic regimes and increases in extreme fire weather, these results may provide managers with options to create more fire-resilient ecosystems. In areas where frequent high-severity fire is undesirable, management activities such as thinning, prescribed fire, or managed wildland fire can be used to moderate fire behavior not only prior to initial fires, but also before subsequent reburns.

Mapping fire probability and severity in a Mediterranean area using different weather and fuel moisture scenarios

NASA Astrophysics Data System (ADS)

Arca, B.; Salis, M.; Bacciu, V.; Duce, P.; Pellizzaro, G.; Ventura, A.; Spano, D.

2009-04-01

Although in many countries lightning is the main cause of ignition, in the Mediterranean Basin the forest fires are predominantly ignited by arson, or by human negligence. The fire season peaks coincide with extreme weather conditions (mainly strong winds, hot temperatures, low atmospheric water vapour content) and high tourist presence. Many works reported that in the Mediterranean Basin the projected impacts of climate change will cause greater weather variability and extreme weather conditions, with drier and hotter summers and heat waves. At long-term scale, climate changes could affect the fuel load and the dead/live fuel ratio, and therefore could change the vegetation flammability. At short-time scale, the increase of extreme weather events could directly affect fuel water status, and it could increase large fire occurrence. In this context, detecting the areas characterized by both high probability of large fire occurrence and high fire severity could represent an important component of the fire management planning. In this work we compared several fire probability and severity maps (fire occurrence, rate of spread, fireline intensity, flame length) obtained for a study area located in North Sardinia, Italy, using FlamMap simulator (USDA Forest Service, Missoula). FlamMap computes the potential fire behaviour characteristics over a defined landscape for given weather, wind and fuel moisture data. Different weather and fuel moisture scenarios were tested to predict the potential impact of climate changes on fire parameters. The study area, characterized by a mosaic of urban areas, protected areas, and other areas subject to anthropogenic disturbances, is mainly composed by fire-prone Mediterranean maquis. The input themes needed to run FlamMap were input as grid of 10 meters; the wind data, obtained using a computational fluid-dynamic model, were inserted as gridded file, with a resolution of 50 m. The analysis revealed high fire probability and severity in most of the areas, and therefore a high potential danger. The FlamMap outputs and the derived fire probability maps can be used in decision support systems for fire spread and behaviour and for fire danger assessment with actual and future fire regimes.

A conceptual framework for ranking crown fire potential in wildland fuelbeds.

Treesearch

Mark D. Schaaf; David V. Sandberg; Maarten D. Schreuder; Cynthia L. Riccardi

2007-01-01

This paper presents a conceptual framework for ranking the crown fire potential of wildland fuelbeds with forest canopies. This approach extends the work by Van Wagner and Rothermel, and introduces several new physical concepts to the modeling of crown fire behavior derived from the reformulated Rothemel surface fire modeling concepts proposed by Sandberg et al. This...

Influence of landscape gradients in wilderness management and spatial climate on fire severity in the Northern Rockies USA, 1984 to 2010

Treesearch

Sandra L. Haire; Carol Miller; Kevin McGarigal

2015-01-01

Management activities, applied over broad scales, can potentially affect attributes of fire regimes including fire severity. Wilderness landscapes provide a natural laboratory for exploring effects of management because in some federally designated wilderness areas the burning of naturally ignited fires is promoted. In order to better understand the contribution of...

Assessing Potential Future Carbon Dynamics with Climate Change and Fire Management in a Mountainous Landscape on the Olympic Peninsula, Washington, USA

NASA Astrophysics Data System (ADS)

Kennedy, R. S.

2010-12-01

Forests of the mountainous landscapes of the maritime Pacific Northwestern USA may have high carbon sequestration potential via their high productivity and moderate to infrequent fire regimes. With climate change, there may be shifts in incidence and severity of fire, especially in the drier areas of the region, via changes to forest productivity and hydrology, and consequent effects to C sequestration and forest structure. To explore this issue, I assessed potential effects of fire management (little fire suppression/wildland fire management/highly effective fire suppression) under two climate change scenarios on future C sequestration dynamics (amounts and spatial pattern) in Olympic National Park, WA, over a 500-year simulation period. I used the simulation platform FireBGCv2, which contains a mechanistic, individual tree succession model, a spatially explicit climate-based biophysical model that uses daily weather data, and a spatially explicit fire model incorporating ignition, spread, and effects on ecosystem components. C sequestration patterns varied over time and spatial and temporal patterns differed somewhat depending on the climate change scenario applied and the fire management methods employed. Under the more extreme climate change scenario with little fire suppression, fires were most frequent and severe and C sequestration decreased. General trends were similar under the more moderate climate change scenario, as compared to current climate, but spatial patterns differed. Both climate change scenarios under highly effective fire suppression showed about 50% of starting total C after the initial transition phase, whereas with 10% fire suppression both scenarios exhibited about 10% of starting amounts. Areas of the landscape that served as refugia for older forest under increasing frequency of high severity fire were also hotspots for C sequestration in a landscape experiencing increasing frequency of disturbance with climate change.

Alternative pathways to landscape transformation: Invasive grasses, burn severity and fire frequency in arid ecosystems

USGS Publications Warehouse

Klinger, Robert C.; Brooks, Matthew L.

2017-01-01

Arid ecosystems are often vulnerable to transformation to invasive-dominated states following fire, but data on persistence of these states are sparse. The grass/fire cycle is a feedback process between invasive annual grasses and fire frequency that often leads to the formation of alternative vegetation states dominated by the invasive grasses. However, other components of fire regimes, such as burn severity, also have the potential to produce long-term vegetation transformations. Our goal was to evaluate the influence of both fire frequency and burn severity on the transformation of woody-dominated communities to communities dominated by invasive grasses in major elevation zones of the Mojave Desert of western North America.We used a chronosequence design to collect data on herbaceous and woody cover at 229 unburned reference plots and 578 plots that burned between 1972 and 2010. We stratified the plots by elevation zone (low, mid, high), fire frequency (1–3 times) and years post-fire (YPF; 1–5, 6–10, 11–20 and 21–40 YPF). Burn severity for each plot was estimated by the difference normalized burn ratio.We identified two broad post-fire successional pathways. One was an outcome of fire frequency, resulting in a strong potential transformation via the grass/fire cycle. The second pathway was driven by burn severity, the critical aspect being that long-term transformation of a community could occur from just one fire in areas that burned at high or sometimes moderate severity. Dominance by invasive grasses was most likely to occur in low-and high-elevation communities; cover of native herbaceous species was often greater than that of invasive grasses in the mid-elevation zone.Synthesis. Invasive grasses can dominate a site that burned only one time in many decades at high severity, or a site that burned at low severity but multiple times in the same time period. However, high burn severity may predispose areas to more frequent fire because they have relatively high cover of invasive annual grass, suggesting burn severity and fire frequency have both independent and synergistic effects. Resilience in vegetation structure following fire in many arid communities may be limited to a narrow window of low burn severity in areas that have not burned in many decades.

Potential shifts in dominant forest cover in interior Alaska driven by variations in fire severity

USGS Publications Warehouse

Barrett, K.; McGuire, A. David; Hoy, E.E.; Kasischke, E.S.

2011-01-01

Large fire years in which >1% of the landscape burns are becoming more frequent in the Alaskan (USA) interior, with four large fire years in the past 10 years, and 79 000 km2 (17% of the region) burned since 2000. We modeled fire severity conditions for the entire area burned in large fires during a large fire year (2004) to determine the factors that are most important in estimating severity and to identify areas affected by deep‐burning fires. In addition to standard methods of assessing severity using spectral information, we incorporated information regarding topography, spatial pattern of burning, and instantaneous characteristics such as fire weather and fire radiative power. Ensemble techniques using regression trees as a base learner were able to determine fire severity successfully using spectral data in concert with other relevant geospatial data. This method was successful in estimating average conditions, but it underestimated the range of severity.This new approach was used to identify black spruce stands that experienced intermediate‐ to high‐severity fires in 2004 and are therefore susceptible to a shift in regrowth toward deciduous dominance or mixed dominance. Based on the output of the severity model, we estimate that 39% (∼4000 km2) of all burned black spruce stands in 2004 had <10 cm of residual organic layer and may be susceptible a postfire shift in plant functional type dominance, as well as permafrost loss. If the fraction of area susceptible to deciduous regeneration is constant for large fire years, the effect of such years in the most recent decade has been to reduce black spruce stands by 4.2% and to increase areas dominated or co‐dominated by deciduous forest stands by 20%. Such disturbance‐driven modifications have the potential to affect the carbon cycle and climate system at regional to global scales.

Potential shifts in dominant forest cover in interior Alaska driven by variations in fire severity.

PubMed

Barrett, K; McGuire, A D; Hoy, E E; Kasischke, E S

2011-10-01

Large fire years in which >1% of the landscape burns are becoming more frequent in the Alaskan (USA) interior, with four large fire years in the past 10 years, and 79 000 km2 (17% of the region) burned since 2000. We modeled fire severity conditions for the entire area burned in large fires during a large fire year (2004) to determine the factors that are most important in estimating severity and to identify areas affected by deep-burning fires. In addition to standard methods of assessing severity using spectral information, we incorporated information regarding topography, spatial pattern of burning, and instantaneous characteristics such as fire weather and fire radiative power. Ensemble techniques using regression trees as a base learner were able to determine fire severity successfully using spectral data in concert with other relevant geospatial data. This method was successful in estimating average conditions, but it underestimated the range of severity. This new approach was used to identify black spruce stands that experienced intermediate- to high-severity fires in 2004 and are therefore susceptible to a shift in regrowth toward deciduous dominance or mixed dominance. Based on the output of the severity model, we estimate that 39% (approximately 4000 km2) of all burned black spruce stands in 2004 had <10 cm of residual organic layer and may be susceptible a postfire shift in plant functional type dominance, as well as permafrost loss. If the fraction of area susceptible to deciduous regeneration is constant for large fire years, the effect of such years in the most recent decade has been to reduce black spruce stands by 4.2% and to increase areas dominated or co-dominated by deciduous forest stands by 20%. Such disturbance-driven modifications have the potential to affect the carbon cycle and climate system at regional to global scales.

Climate change, fire management, and ecological services in the southwestern US

USGS Publications Warehouse

Hurteau, Matthew D.; Bradford, John B.; Fulé, Peter Z.; Taylor, Alan H.; Martin, Katherine L.

2014-01-01

The diverse forest types of the southwestern US are inseparable from fire. Across climate zones in California, Nevada, Arizona, and New Mexico, fire suppression has left many forest types out of sync with their historic fire regimes. As a result, high fuel loads place them at risk of severe fire, particularly as fire activity increases due to climate change. A legacy of fire exclusion coupled with a warming climate has led to increasingly large and severe wildfires in many southwest forest types. Climate change projections include an extended fire season length due to earlier snowmelt and a general drying trend due to rising temperatures. This suggests the future will be warmer and drier regardless of changes in precipitation. Hotter, drier conditions are likely to increase forest flammability, at least initially. Changes in climate alone have the potential to alter the distribution of vegetation types within the region, and climate-driven shifts in vegetation distribution are likely to be accelerated when coupled with stand-replacing fire. Regardless of the rate of change, the interaction of climate and fire and their effects on Southwest ecosystems will alter the provisioning of ecosystem services, including carbon storage and biodiversity. Interactions between climate, fire, and vegetation growth provide a source of great uncertainty in projecting future fire activity in the region, as post-fire forest recovery is strongly influenced by climate and subsequent fire frequency. Severe fire can be mitigated with fuels management including prescribed fire, thinning, and wildfire management, but new strategies are needed to ensure the effectiveness of treatments across landscapes. We review the current understanding of the relationship between fire and climate in the Southwest, both historical and projected. We then discuss the potential implications of climate change for fire management and examine the potential effects of climate change and fire on ecosystem services. We conclude with an assessment of the role of fire management in an increasingly flammable Southwest.

Assessing European wild fire vulnerability

NASA Astrophysics Data System (ADS)

Oehler, F.; Oliveira, S.; Barredo, J. I.; Camia, A.; Ayanz, J. San Miguel; Pettenella, D.; Mavsar, R.

2012-04-01

Wild fire vulnerability is a measure of potential socio-economic damage caused by a fire in a specific area. As such it is an important component of long-term fire risk management, helping policy-makers take informed decisions about adequate expenditures for fire prevention and suppression, and to target those regions at highest risk. This paper presents a first approach to assess wild fire vulnerability at the European level. A conservative approach was chosen that assesses the cost of restoring the previous land cover after a potential fire. Based on the CORINE Land Cover, a restoration cost was established for each land cover class at country level, and an average restoration time was assigned according to the recovery capacity of the land cover. The damage caused by fire was then assessed by discounting the cost of restoring the previous land cover over the restoration period. Three different vulnerability scenarios were considered assuming low, medium and high fire severity causing different levels of damage. Over Europe, the potential damage of wild land fires ranges from 10 - 13, 732 Euro*ha-1*yr-1 for low fire severity, 32 - 45,772 Euro*ha-1*yr-1 for medium fire severity and 54 - 77,812 Euro*ha-1*yr-1 for high fire severity. The least vulnerable are natural grasslands, moors and heathland and sclerophyllous vegetation, while the highest cost occurs for restoring broad-leaved forest. Preliminary validation comparing these estimates with official damage assessments for past fires shows reasonable results. The restoration cost approach allows for a straightforward, data extensive assessment of fire vulnerability at European level. A disadvantage is the inherent simplification of the evaluation procedure with the underestimation of non-markets goods and services. Thus, a second approach has been developed, valuing individual wild land goods and services and assessing their annual flow which is lost for a certain period of time in case of a fire event. However, due to limitations in data availability, this approach of environmental accounting is not fully implemented yet. Keywords: fire vulnerability, damage assessment, land cover restoration, long-term fire risk, European scale

Quantity, composition and water contamination potential of ash produced under different wildfire severities.

PubMed

Santín, Cristina; Doerr, Stefan H; Otero, Xosé L; Chafer, Chris J

2015-10-01

Wildfires frequently threaten water quality through the transfer of eroded ash and soil into rivers and reservoirs. The ability to anticipate risks for water resources from wildfires is fundamental for implementing effective fire preparedness plans and post-fire mitigation measures. Here we present a new approach that allows quantifying the amount and characteristics of ash generated under different wildfire severities and its respective water contamination potential. This approach is applied to a wildfire in an Australian dry sclerophyll eucalypt forest, but can be adapted for use in other environments. The Balmoral fire of October 2013 affected 12,694 ha of Sydney's forested water supply catchment. It produced substantial ash loads that increased with fire severity, with 6, 16 and 34 Mg ha(-1) found in areas affected by low, high and extreme fire severity, respectively. Ash bulk density was also positively related to fire severity. The increase with fire severity in the total load and bulk density of the ash generated is mainly attributed to a combination of associated increases in (i) total amount of fuel affected by fire and (ii) contribution of charred mineral soil to the ash layer. Total concentrations of pollutants and nutrients in ash were mostly unrelated to fire severity and relatively low compared to values reported for wildfire ash in other environments (e.g. 4.0-7.3mg As kg(-1); 2.3-4.1 B mg kg(-1); 136-154 P mg kg(-1)). Solubility of the elements analysed was also low, less than 10% of the total concentration for all elements except for B (6-14%) and Na (30-50%). This could be related to a partial loss of soluble components by leaching and/or wind erosion before the ash sampling (10 weeks after the fire and before major ash mobilisation by water erosion). Even with their relatively low concentrations of potential pollutants, the substantial total ash loads found here represent a water contamination risk if transported into the hydrological network during severe erosion events. For example, up to 4 Mg of ash-derived P could be delivered into a single water supply reservoir. Copyright © 2015 Elsevier Inc. All rights reserved.

Mean composite fire severity metrics computed with Google Earth Engine offer improved accuracy and expanded mapping potential

USGS Publications Warehouse

Parks, Sean; Holsinger, Lisa M.; Voss, Morgan; Loehman, Rachel A.; Robinson, Nathaniel P.

2018-01-01

Landsat-based fire severity datasets are an invaluable resource for monitoring and research purposes. These gridded fire severity datasets are generally produced with pre-and post-fire imagery to estimate the degree of fire-induced ecological change. Here, we introduce methods to produce three Landsat-based fire severity metrics using the Google Earth Engine (GEE) platform: the delta normalized burn ratio (dNBR), the relativized delta normalized burn ratio (RdNBR), and the relativized burn ratio (RBR). Our methods do not rely on time-consuming a priori scene selection and instead use a mean compositing approach in which all valid pixels (e.g. cloud-free) over a pre-specified date range (pre- and post-fire) are stacked and the mean value for each pixel over each stack is used to produce the resulting fire severity datasets. This approach demonstrates that fire severity datasets can be produced with relative ease and speed compared the standard approach in which one pre-fire and post-fire scene are judiciously identified and used to produce fire severity datasets. We also validate the GEE-derived fire severity metrics using field-based fire severity plots for 18 fires in the western US. These validations are compared to Landsat-based fire severity datasets produced using only one pre- and post-fire scene, which has been the standard approach in producing such datasets since their inception. Results indicate that the GEE-derived fire severity datasets show improved validation statistics compared to parallel versions in which only one pre-fire and post-fire scene are used. We provide code and a sample geospatial fire history layer to produce dNBR, RdNBR, and RBR for the 18 fires we evaluated. Although our approach requires that a geospatial fire history layer (i.e. fire perimeters) be produced independently and prior to applying our methods, we suggest our GEE methodology can reasonably be implemented on hundreds to thousands of fires, thereby increasing opportunities for fire severity monitoring and research across the globe.

Climatic and weather factors affecting fire occurrence and behavior

Treesearch

Randall P. Benson; John O. Roads; David R. Weise

2009-01-01

Weather and climate have a profound influence on wildland fire ignition potential, fire behavior, and fire severity. Local weather and climate are affected by large-scale patterns of winds over the hemispheres that predispose wildland fuels to fire. The characteristics of wildland fuels, especially the moisture content, ultimately determine fire behavior and the impact...

Modeling hazardous fire potential within a completed fuel treatment network in the northern Sierra Nevada

Treesearch

Brandon M. Collins; Heather A. Kramer; Kurt Menning; Colin Dillingham; David Saah; Peter A. Stine; Scott L. Stephens

2013-01-01

We built on previous work by performing a more in-depth examination of a completed landscape fuel treatment network. Our specific objectives were: (1) model hazardous fire potential with and without the treatment network, (2) project hazardous fire potential over several decades to assess fuel treatment network longevity, and (3) assess fuel treatment effectiveness and...

The quest for all-purpose plants

Treesearch

Susan L. Frommer; David R. Weise

1995-01-01

The fire safety of a home in the wildland/urban interface is influenced by several factors-one of which is the presence and proximity of vegetation to the home. Landscaping may either provide a significant barrier to fire spread and thus potentially increase a home's fire safety or favor fire spread and reduce a home's fire safety. However, fire safety of...

Fire severity unaffected by spruce beetle outbreak in spruce-fir forests in southwestern Colorado.

PubMed

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 (< 5 yr from outbreak to time of fire) spruce beetle infestation affected fire severity. Contrary to the expectation that bark beetle infestation alters subsequent fire severity, correlation and multivariate generalized linear regression analysis revealed no influence of pre-fire spruce beetle severity on nearly all field or remotely sensed measurements of fire severity. Findings were consistent across moderate and extreme burning conditions. In comparison to severity of the pre-fire beetle outbreak, we found that topography, pre-outbreak basal area, and weather conditions exerted a stronger effect on fire severity. Our finding that beetle infestation did not alter fire severity is consistent with previous retrospective studies examining fire activity following other bark beetle outbreaks and reiterates the overriding influence of climate that creates conditions conducive to large, high-severity fires in the subalpine zone of Colorado. Both bark beetle outbreaks and wildfires have increased autonomously due to recent climate variability, but this study does not support the expectation that post-beetle outbreak forests will alter fire severity, a result that has important implications for management and policy decisions.

Pattern and process of prescribed fires influence effectiveness at reducing wildfire severity in dry coniferous forests

USGS Publications Warehouse

Arkle, Robert S.; Pilliod, David S.; Welty, Justin L.

2012-01-01

We examined the effects of three early season (spring) prescribed fires on burn severity patterns of summer wildfires that occurred 1–3 years post-treatment in a mixed conifer forest in central Idaho. Wildfire and prescribed fire burn severities were estimated as the difference in normalized burn ratio (dNBR) using Landsat imagery. We used GIS derived vegetation, topography, and treatment variables to generate models predicting the wildfire burn severity of 1286–5500 30-m pixels within and around treated areas. We found that wildfire severity was significantly lower in treated areas than in untreated areas and significantly lower than the potential wildfire severity of the treated areas had treatments not been implemented. At the pixel level, wildfire severity was best predicted by an interaction between prescribed fire severity, topographic moisture, heat load, and pre-fire vegetation volume. Prescribed fire severity and vegetation volume were the most influential predictors. Prescribed fire severity, and its influence on wildfire severity, was highest in relatively warm and dry locations, which were able to burn under spring conditions. In contrast, wildfire severity peaked in cooler, more mesic locations that dried later in the summer and supported greater vegetation volume. We found considerable evidence that prescribed fires have landscape-level influences within treatment boundaries; most notable was an interaction between distance from the prescribed fire perimeter and distance from treated patch edges, which explained up to 66% of the variation in wildfire severity. Early season prescribed fires may not directly target the locations most at risk of high severity wildfire, but proximity of these areas to treated patches and the discontinuity of fuels following treatment may influence wildfire severity and explain how even low severity treatments can be effective management tools in fire-prone landscapes.

Effectiveness of Prescribed Fire as a Fuel Treatment in Californian Coniferous Forests

Treesearch

Nicole M. Vaillant; JoAnn Fites-Kaufman; Scott L. Stephens

2006-01-01

Effective fire suppression for the past century has altered forest structure and increased fuel loads. Prescribed fire as a fuels treatment can reduce wildfire size and severity. This study investigates how prescribed fire affects fuel loads, forest structure, potential fire behavior, and modeled tree mortality at 80th, 90th, and 97.5th percentile fire weather...

Assessing fire impacts on the carbon stability of fire-tolerant forests.

PubMed

Bennett, Lauren T; Bruce, Matthew J; Machunter, Josephine; Kohout, Michele; Krishnaraj, Saravanan Jangammanaidu; Aponte, Cristina

2017-12-01

The carbon stability of fire-tolerant forests is often assumed but less frequently assessed, limiting the potential to anticipate threats to forest carbon posed by predicted increases in forest fire activity. Assessing the carbon stability of fire-tolerant forests requires multi-indicator approaches that recognize the myriad ways that fires influence the carbon balance, including combustion, deposition of pyrogenic material, and tree death, post-fire decomposition, recruitment, and growth. Five years after a large-scale wildfire in southeastern Australia, we assessed the impacts of low- and high-severity wildfire, with and without prescribed fire (≤10 yr before), on carbon stocks in multiple pools, and on carbon stability indicators (carbon stock percentages in live trees and in small trees, and carbon stocks in char and fuels) in fire-tolerant eucalypt forests. Relative to unburned forest, high-severity wildfire decreased short-term (five-year) carbon stability by significantly decreasing live tree carbon stocks and percentage stocks in live standing trees (reflecting elevated tree mortality), by increasing the percentage of live tree carbon in small trees (those vulnerable to the next fire), and by potentially increasing the probability of another fire through increased elevated fine fuel loads. In contrast, low-severity wildfire enhanced carbon stability by having negligible effects on aboveground stocks and indicators, and by significantly increasing carbon stocks in char and, in particular, soils, indicating pyrogenic carbon accumulation. Overall, recent preceding prescribed fire did not markedly influence wildfire effects on short-term carbon stability at stand scales. Despite wide confidence intervals around mean stock differences, indicating uncertainty about the magnitude of fire effects in these natural forests, our assessment highlights the need for active management of carbon assets in fire-tolerant eucalypt forests under contemporary fire regimes. Decreased live tree carbon and increased reliance on younger cohorts for carbon recovery after high-severity wildfire could increase vulnerabilities to imminent fires, leading to decisions about interventions to maintain the productivity of some stands. Our multi-indicator assessment also highlights the importance of considering all carbon pools, particularly pyrogenic reservoirs like soils, when evaluating the potential for prescribed fire regimes to mitigate the carbon costs of wildfires in fire-prone landscapes. © 2017 by the Ecological Society of America.

Fire activity and severity in the western US vary along proxy gradients representing fuel amount and fuel moisture.

PubMed

Parks, Sean A; Parisien, Marc-André; Miller, Carol; Dobrowski, Solomon Z

2014-01-01

Numerous theoretical and empirical studies have shown that wildfire activity (e.g., area burned) at regional to global scales may be limited at the extremes of environmental gradients such as productivity or moisture. Fire activity, however, represents only one component of the fire regime, and no studies to date have characterized fire severity along such gradients. Given the importance of fire severity in dictating ecological response to fire, this is a considerable knowledge gap. For the western US, we quantify relationships between climate and the fire regime by empirically describing both fire activity and severity along two climatic water balance gradients, actual evapotranspiration (AET) and water deficit (WD), that can be considered proxies for fuel amount and fuel moisture, respectively. We also concurrently summarize fire activity and severity among ecoregions, providing an empirically based description of the geographic distribution of fire regimes. Our results show that fire activity in the western US increases with fuel amount (represented by AET) but has a unimodal (i.e., humped) relationship with fuel moisture (represented by WD); fire severity increases with fuel amount and fuel moisture. The explicit links between fire regime components and physical environmental gradients suggest that multivariable statistical models can be generated to produce an empirically based fire regime map for the western US. Such models will potentially enable researchers to anticipate climate-mediated changes in fire recurrence and its impacts based on gridded spatial data representing future climate scenarios.

Fire Activity and Severity in the Western US Vary along Proxy Gradients Representing Fuel Amount and Fuel Moisture

PubMed Central

Parks, Sean A.; Parisien, Marc-André; Miller, Carol; Dobrowski, Solomon Z.

2014-01-01

Numerous theoretical and empirical studies have shown that wildfire activity (e.g., area burned) at regional to global scales may be limited at the extremes of environmental gradients such as productivity or moisture. Fire activity, however, represents only one component of the fire regime, and no studies to date have characterized fire severity along such gradients. Given the importance of fire severity in dictating ecological response to fire, this is a considerable knowledge gap. For the western US, we quantify relationships between climate and the fire regime by empirically describing both fire activity and severity along two climatic water balance gradients, actual evapotranspiration (AET) and water deficit (WD), that can be considered proxies for fuel amount and fuel moisture, respectively. We also concurrently summarize fire activity and severity among ecoregions, providing an empirically based description of the geographic distribution of fire regimes. Our results show that fire activity in the western US increases with fuel amount (represented by AET) but has a unimodal (i.e., humped) relationship with fuel moisture (represented by WD); fire severity increases with fuel amount and fuel moisture. The explicit links between fire regime components and physical environmental gradients suggest that multivariable statistical models can be generated to produce an empirically based fire regime map for the western US. Such models will potentially enable researchers to anticipate climate-mediated changes in fire recurrence and its impacts based on gridded spatial data representing future climate scenarios. PMID:24941290

Predicting Fire Severity and Hydrogeomorphic Effects for Wildland Fire Decision Support

NASA Astrophysics Data System (ADS)

Hyde, K.; Woods, S. W.; Calkin, D.; Ryan, K.; Keane, R.

2007-12-01

The Wildland Fire Decision Support System (WFDSS) uses the Fire Spread Probability (FSPro) model to predict the spatial extent of fire, and to assess values-at-risk within probable spread zones. This information is used to support Appropriate Management Response (AMR), which involves decision making regarding fire-fighter deployment, fire suppression requirements, and identification of areas where fire may be safely permitted to take its course. Current WFDSS assessments are generally limited to a binary prediction of whether or not a fire will reach a given location and an assessment of the infrastructure which may be damaged or destroyed by fire. However, an emerging challenge is to expand the capabilities of WFDSS so that it also estimates the probable fire severity, and hence the effect on soil, vegetation and on hydrologic and geomorphic processes such as runoff and soil erosion. We present a conceptual framework within which derivatives of predictive fire modelling are used to predict impacts upon vegetation and soil, from which fire severity and probable post-fire watershed response can be inferred, before a fire actually occurs. Fire severity predictions are validated using Burned Area Reflectance Classification imagery. Recent tests indicate that satellite derived BARC images are a simple and effective means to predict post-fire erosion response based on relative vegetation disturbance. A fire severity prediction which reasonably approximates a BARC image may therefore be used to assess post-fire erosion and flood potential before fire reaches an area. This information may provide a new avenue of reliable support for fire management decisions.

Previous fires moderate burn severity of subsequent wildland fires in two large western US wilderness areas

Treesearch

Sean A. Parks; Carol Miller; Cara R. Nelson; Zachary A. Holden

2014-01-01

Wildland fire is an important natural process in many ecosystems. However, fire exclusion has reduced frequency of fire and area burned in many dry forest types, which may affect vegetation structure and composition, and potential fire behavior. In forests of the western U.S., these effects pose a challenge for fire and land managers who seek to restore the ecological...

High-severity fire: evaluating its key drivers and mapping its probability across western US forests

NASA Astrophysics Data System (ADS)

Parks, Sean A.; Holsinger, Lisa M.; Panunto, Matthew H.; Jolly, W. Matt; Dobrowski, Solomon Z.; Dillon, Gregory K.

2018-04-01

Wildland fire is a critical process in forests of the western United States (US). Variation in fire behavior, which is heavily influenced by fuel loading, terrain, weather, and vegetation type, leads to heterogeneity in fire severity across landscapes. The relative influence of these factors in driving fire severity, however, is poorly understood. Here, we explore the drivers of high-severity fire for forested ecoregions in the western US over the period 2002–2015. Fire severity was quantified using a satellite-inferred index of severity, the relativized burn ratio. For each ecoregion, we used boosted regression trees to model high-severity fire as a function of live fuel, topography, climate, and fire weather. We found that live fuel, on average, was the most important factor driving high-severity fire among ecoregions (average relative influence = 53.1%) and was the most important factor in 14 of 19 ecoregions. Fire weather was the second most important factor among ecoregions (average relative influence = 22.9%) and was the most important factor in five ecoregions. Climate (13.7%) and topography (10.3%) were less influential. We also predicted the probability of high-severity fire, were a fire to occur, using recent (2016) satellite imagery to characterize live fuel for a subset of ecoregions in which the model skill was deemed acceptable (n = 13). These ‘wall-to-wall’ gridded ecoregional maps provide relevant and up-to-date information for scientists and managers who are tasked with managing fuel and wildland fire. Lastly, we provide an example of the predicted likelihood of high-severity fire under moderate and extreme fire weather before and after fuel reduction treatments, thereby demonstrating how our framework and model predictions can potentially serve as a performance metric for land management agencies tasked with reducing hazardous fuel across large landscapes.

Enhanced fire-related traits may contribute to the invasiveness of Downy Brome (Bromus tectorum)

USDA-ARS?s Scientific Manuscript database

Although several invasive species have induced changes to the fire regime of invaded ecosystems, potential intraspecific shifts in fire-related traits that might enhance their invasion success, have never been addressed. We assumed that traits conferring persistence and competitiveness in post-fire ...

The potential impact of regional climate change on fire weather in the United States

Treesearch

Ying Tang; Shiyuan Zhong; Lifeng Luo; Xindi Bian; Warren E. Heilman; Julie. Winkler

2015-01-01

Climate change is expected to alter the frequency and severity of atmospheric conditions conducive for wildfires. In this study, we assess potential changes in fire weather conditions for the contiguous United States using the Haines Index (HI), a fire weather index that has been employed operationally to detect atmospheric conditions favorable for large and erratic...

Assessment of the FARSITE model for predicting fire behavior in the Southern Appalachian Mountains

Treesearch

Ross J. Phillips; Thomas A. Waldrop; Dean M. Simon

2006-01-01

Fuel reduction treatments are necessary in fire-adapted ecosystems where fire has been excluded for decades and the potential for severe wildfire is high. Using the Fire Area Simulator, FARSITE, we examined the spatial and temporal effects of these treatments on fire behavior in the Southern Appalachian Mountains. With measurements from temperature sensors during...

Postfire soil burn severity mapping with hyperspectral image unmixing

Treesearch

Peter R. Robichaud; Sarah A. Lewis; Denise Y. M. Laes; Andrew T. Hudak; Raymond F. Kokaly; Joseph A. Zamudio

2007-01-01

Burn severity is mapped after wildfires to evaluate immediate and long-term fire effects on the landscape. Remotely sensed hyperspectral imagery has the potential to provide important information about fine-scale ground cover components that are indicative of burn severity after large wildland fires. Airborne hyperspectral imagery and ground data were collected after...

A fuel treatment reduces potential fire severity and increases suppression efficiency in a Sierran mixed conifer forest

Treesearch

Jason J. Moghaddas

2006-01-01

Fuel treatments are being widely implemented on public and private lands across the western U.S. While scientists and managers have an understanding of how fuel treatments can modify potential fire behavior under modeled conditions, there is limited information on how treatments perform under real wildfire conditions in Sierran mixed conifer forests. The Bell Fire...

The efficacy of fuel treatment in mitigating property loss during wildfires: Insights from analysis of the severity of the catastrophic fires in 2009 in Victoria, Australia.

PubMed

Price, Owen F; Bradstock, Ross A

2012-12-30

Treatment of fuel (e.g. prescribed fire, logging) in fire-prone ecosystems is done to reduce risks to people and their property but effects require quantification, particularly under severe weather conditions when the destructive potential of fires on human infrastructure is maximised. We analysed the relative effects of fuel age (i.e. indicative of the effectiveness of prescribed fire) and logging on remotely sensed (SPOT imagery) severity of fires which occurred in eucalypt forests in Victoria, Australia in 2009. These fires burned under the most severe weather conditions recorded in Australia and caused large losses of life and property. Statistical models of the probability of contrasting extremes of severity (crown fire versus fire confined to the understorey) were developed based on effects of fuel age, logging, weather, topography and forest type. Weather was the primary influence on severity, though it was reduced at low fuel ages in Moderate but not Catastrophic, Very High or Low fire-weather conditions. Probability of crown fires was higher in recently logged areas than in areas logged decades before, indicating likely ineffectiveness as a fuel treatment. The results suggest that recently burnt areas (up to 5-10 years) may reduce the intensity of the fire but not sufficiently to increase the chance of effective suppression under severe weather conditions. Since house loss was most likely under these conditions (67%), effects of prescribed burning across landscapes on house loss are likely to be small when weather conditions are severe. Fuel treatments need to be located close to houses in order to effectively mitigate risk of loss. Copyright © 2012 Elsevier Ltd. All rights reserved.

Near-term probabilistic forecast of significant wildfire events for the Western United States

Treesearch

Haiganoush K. Preisler; Karin L. Riley; Crystal S. Stonesifer; Dave E. Calkin; Matt Jolly

2016-01-01

Fire danger and potential for large fires in the United States (US) is currently indicated via several forecasted qualitative indices. However, landscape-level quantitative forecasts of the probability of a large fire are currently lacking. In this study, we present a framework for forecasting large fire occurrence - an extreme value event - and evaluating...

Climatic and Landscape Influences on Fire Regimes from 1984 to 2010 in the Western United States

PubMed Central

Liu, Zhihua; Wimberly, Michael C.

2015-01-01

An improved understanding of the relative influences of climatic and landscape controls on multiple fire regime components is needed to enhance our understanding of modern fire regimes and how they will respond to future environmental change. To address this need, we analyzed the spatio-temporal patterns of fire occurrence, size, and severity of large fires (> 405 ha) in the western United States from 1984–2010. We assessed the associations of these fire regime components with environmental variables, including short-term climate anomalies, vegetation type, topography, and human influences, using boosted regression tree analysis. Results showed that large fire occurrence, size, and severity each exhibited distinctive spatial and spatio-temporal patterns, which were controlled by different sets of climate and landscape factors. Antecedent climate anomalies had the strongest influences on fire occurrence, resulting in the highest spatial synchrony. In contrast, climatic variability had weaker influences on fire size and severity and vegetation types were the most important environmental determinants of these fire regime components. Topography had moderately strong effects on both fire occurrence and severity, and human influence variables were most strongly associated with fire size. These results suggest a potential for the emergence of novel fire regimes due to the responses of fire regime components to multiple drivers at different spatial and temporal scales. Next-generation approaches for projecting future fire regimes should incorporate indirect climate effects on vegetation type changes as well as other landscape effects on multiple components of fire regimes. PMID:26465959

Fire behavior, weather, and burn severity of the 2007 Anaktuvuk River tundra fire, North Slope, Alaska

Treesearch

Benjamin M. Jones; Crystal A. Kolden; Randi Jandt; John T. Abatzoglu; Frank Urban; Christopher D. Arp

2009-01-01

In 2007, the Anaktuvuk River Fire (ARF) became the largest recorded tundra fire on the North Slope of Alaska. The ARF burned for nearly three months, consuming more than 100,000 ha. At its peak in early September, the ARF burned at a rate of 7000 ha d-1. The conditions potentially responsible for this large tundra fire include modeled record high...

Modeling tree-level fuel connectivity to evaluate the effectiveness of thinning treatments for reducing crown fire potential

Treesearch

Marco A. Contreras; Russell A. Parsons; Woodam Chung

2012-01-01

Land managers have been using fire behavior and simulation models to assist in several fire management tasks. These widely-used models use average attributes to make stand-level predictions without considering spatial variability of fuels within a stand. Consequently, as the existing models have limitations in adequately modeling crown fire initiation and propagation,...

Climate change impact on fire probability and severity in Mediterranean areas

Treesearch

Bachisio Arca; Grazia Pellizzaro; Pierpaolo Duce; Michele Salis; Valentina Bacciu; Donatella Spano; Alan Ager; Mark Finney

2010-01-01

Fire is one of the most significant threats for the Mediterranean forested areas. Global change may increase the wildland fire risk due to the combined effect of air temperature and humidity on fuel status, and the effect of wind speed on fire behaviour. This paper investigated the potential effect of the climate changes predicted for the Mediterranean basin by a...

Do multiple fires interact to affect vegetation structure in temperate eucalypt forests?

PubMed

Haslem, Angie; Leonard, Steve W J; Bruce, Matthew J; Christie, Fiona; Holland, Greg J; Kelly, Luke T; MacHunter, Josephine; Bennett, Andrew F; Clarke, Michael F; York, Alan

2016-12-01

Fire plays an important role in structuring vegetation in fire-prone regions worldwide. Progress has been made towards documenting the effects of individual fire events and fire regimes on vegetation structure; less is known of how different fire history attributes (e.g., time since fire, fire frequency) interact to affect vegetation. Using the temperate eucalypt foothill forests of southeastern Australia as a case study system, we examine two hypotheses about such interactions: (1) post-fire vegetation succession (e.g., time-since-fire effects) is influenced by other fire regime attributes and (2) the severity of the most recent fire overrides the effect of preceding fires on vegetation structure. Empirical data on vegetation structure were collected from 540 sites distributed across central and eastern Victoria, Australia. Linear mixed models were used to examine these hypotheses and determine the relative influence of fire and environmental attributes on vegetation structure. Fire history measures, particularly time since fire, affected several vegetation attributes including ground and canopy strata; others such as low and sub-canopy vegetation were more strongly influenced by environmental characteristics like rainfall. There was little support for the hypothesis that post-fire succession is influenced by fire history attributes other than time since fire; only canopy regeneration was influenced by another variable (fire type, representing severity). Our capacity to detect an overriding effect of the severity of the most recent fire was limited by a consistently weak effect of preceding fires on vegetation structure. Overall, results suggest the primary way that fire affects vegetation structure in foothill forests is via attributes of the most recent fire, both its severity and time since its occurrence; other attributes of fire regimes (e.g., fire interval, frequency) have less influence. The strong effect of environmental drivers, such as rainfall and topography, on many structural features show that foothill forest vegetation is also influenced by factors outside human control. While fire is amenable to human management, results suggest that at broad scales, structural attributes of these forests are relatively resilient to the effects of current fire regimes. Nonetheless, the potential for more frequent severe fires at short intervals, associated with a changing climate and/or fire management, warrant further consideration. © 2016 by the Ecological Society of America.

Runoff Response to Rainfall in Small Catchments Burned by the 2015 Valley Fire

NASA Astrophysics Data System (ADS)

Wagenbrenner, J. W.; Coe, D. B. R.; Lindsay, D.

2016-12-01

Burned areas often produce runoff volumes and peak flows much larger than unburned forests. However, very few studies demonstrate the effect of burn severity on runoff responses, and post-fire data are especially sparse in California. We measured the effects of different degrees of burn severity on rainfall-runoff responses in six small catchments (0.15-0.65 ha) in the Northern Coast Ranges. Weirs and tipping bucket rain gages were installed after the 2015 Valley Fire and prior to any substantial rainfall. In the first wet season (Nov 2015-May 2016), one runoff event was recorded in the catchment with the lowest burn severity (42% bare soil), while 13 runoff events occurred in the catchment with the highest burn severity (68% bare soil). Preliminary results indicate the thirty minute maximum rainfall intensity that generated runoff ranged from 27 mm hr-1 in the lowest severity catchment to only 8.6 mm hr-1 in the highest severity catchment. Peak flow rates for the most intense event (27 mm hr-1), a two-year, 30-min storm, were 1.1 m3 s-1 km-2 in the lowest severity catchment and 17 m3 s-1 km-2 in the highest severity catchment. Longer duration, moderate intensity rain events produced runoff in the highest severity catchments but not the lowest severity catchments. These results are on the high end of the range of post-fire peak flow rates reported in the western US and provide an idea of potential post-fire flood potential to land and emergency management agencies.

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

USGS Publications Warehouse

Barrett, Kirsten; Kasischke, Eric S.

2013-01-01

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

Integrating remote sensing and terrain data in forest fire modeling

NASA Astrophysics Data System (ADS)

Medler, Michael Johns

Forest fire policies are changing. Managers now face conflicting imperatives to re-establish pre-suppression fire regimes, while simultaneously preventing resource destruction. They must, therefore, understand the spatial patterns of fires. Geographers can facilitate this understanding by developing new techniques for mapping fire behavior. This dissertation develops such techniques for mapping recent fires and using these maps to calibrate models of potential fire hazards. In so doing, it features techniques that strive to address the inherent complexity of modeling the combinations of variables found in most ecological systems. Image processing techniques were used to stratify the elements of terrain, slope, elevation, and aspect. These stratification images were used to assure sample placement considered the role of terrain in fire behavior. Examination of multiple stratification images indicated samples were placed representatively across a controlled range of scales. The incorporation of terrain data also improved preliminary fire hazard classification accuracy by 40%, compared with remotely sensed data alone. A Kauth-Thomas transformation (KT) of pre-fire and post-fire Thematic Mapper (TM) remotely sensed data produced brightness, greenness, and wetness images. Image subtraction indicated fire induced change in brightness, greenness, and wetness. Field data guided a fuzzy classification of these change images. Because fuzzy classification can characterize a continuum of a phenomena where discrete classification may produce artificial borders, fuzzy classification was found to offer a range of fire severity information unavailable with discrete classification. These mapped fire patterns were used to calibrate a model of fire hazards for the entire mountain range. Pre-fire TM, and a digital elevation model produced a set of co-registered images. Training statistics were developed from 30 polygons associated with the previously mapped fire severity. Fuzzy classifications of potential burn patterns were produced from these images. Observed field data values were displayed over the hazard imagery to indicate the effectiveness of the model. Areas that burned without suppression during maximum fire severity are predicted best. Areas with widely spaced trees and grassy understory appear to be misrepresented, perhaps as a consequence of inaccuracies in the initial fire mapping.

Fire weather in western Oregon and western Washington in 1952 compared with other years.

Treesearch

Owen P. Cramer

1953-01-01

How did the potential burning conditions of the 1952 fire season compare with those of previous years? The answer is important to those who protect forests from fire. Knowing the relative severity of the burning conditions will help them judge the effectiveness of their fire protection programs. This paper reports ratings of the weather factors most closely related to...

Potential release of fibers from burning carbon composites. [aircraft fires

NASA Technical Reports Server (NTRS)

Bell, V. L.

1980-01-01

A comprehensive experimental carbon fiber source program was conducted to determine the potential for the release of conductive carbon fibers from burning composites. Laboratory testing determined the relative importance of several parameters influencing the amounts of single fibers released, while large-scale aviation jet fuel pool fires provided realistic confirmation of the laboratory data. The dimensions and size distributions of fire-released carbon fibers were determined, not only for those of concern in an electrical sense, but also for those of potential interest from a health and environmental standpoint. Fire plume and chemistry studies were performed with large pool fires to provide an experimental input into an analytical modelling of simulated aircraft crash fires. A study of a high voltage spark system resulted in a promising device for the detection, counting, and sizing of electrically conductive fibers, for both active and passive modes of operation.

Measuring and Modeling the Effects of Alternate Post-Fire Successional Trajectories on Boreal Forest Carbon Dynamics

NASA Astrophysics Data System (ADS)

Loranty, M. M.; Goetz, S. J.; Mack, M. C.; Alexander, H. D.; Beck, P. S.

2011-12-01

High latitude ecosystems are experiencing amplified climate warming, and recent evidence suggests concurrent intensification of fire disturbance regimes. In central Alaskan boreal forests, severe burns consume more of the soil organic layer, resulting in increased establishment of deciduous seedlings and altered post-fire stand composition with increased deciduous dominance. Quantifying differences in ecosystem carbon (C) dynamics between forest successional trajectories in response to burn severity is essential for understanding potential changes in regional or global feedbacks between boreal forests and climate. We used the Biome BioGeochemical Cycling model (Biome-BGC) to quantify differences in C stocks and fluxes associated with alternate post-fire successional trajectories related to fire severity. A version of Biome-BGC that allows alternate competing vegetation types was calibrated against a series of aboveground biomass observations from chronosequences of stands with differing post-fire successional trajectories characterized by the proportion of deciduous biomass. The model was able to reproduce observed patterns of biomass accumulation after fire, with stands dominated by deciduous species sequestering more C at a faster rate than stands dominated by conifers. Modeled C fluxes suggest that stands dominated by deciduous species are a stronger sink of atmospheric C soon after disturbance than coniferous stands. These results agree with the few available C flux observations. We use a historic database in conjunction with a map of deciduous canopy cover to explore the consequences of ongoing and potential future changes in the fire regime on central Alaskan C balance.

Application of the relative energy release criteria to enclosure fire testing. [aircraft compartments

NASA Technical Reports Server (NTRS)

Roschke, E. J.; Coulbert, C. D.

1979-01-01

The five relative energy release criteria (RERC) which are a first step towards formulating a unified concept that can be applied to the development of fires in enclosures, place upper bounds on the rate and amount of energy released during a fire. They are independent, calculated readily, and may be applied generally to any enclosure regardless of size. They are useful in pretest planning and for interpreting experimental data. Data from several specific fire test programs were examined to evaluate the potential use of RERC to provide test planning guidelines. The RERC were compared with experimental data obtained in full-scale enclosures. These results confirm that in general the RERC do identify the proper limiting constraints on enclosure fire development and determine the bounds of the fire development envelope. Plotting actual fire data against the RERC reveals new valid insights into fire behavior and reveals the controlling constraints in fire development. The RERC were calculated and plotted for several descrpitions of full-scale fires in various aircraft compartments.

Spatiotemporal patterns of fire-induced forest mortality in boreal regions and its potential drivers

NASA Astrophysics Data System (ADS)

Yang, J.; Tian, H.; Pan, S.; Hansen, M.; Wang, Y.

2017-12-01

Wildfire is the major natural disturbance in boreal forests, which have substantially affected various biological and biophysical processes. Although a few previous studies examined fire severity in boreal regions and reported a higher fire-induced forest mortality in boreal North America than in boreal Eurasia, it remains unclear how this mortality changes over time and how environmental factors affect the temporal dynamics of mortality at a large scale. By using a combination of multiple sources of satellite observations, we investigate the spatiotemporal patterns of fire-induced forest mortality in boreal regions, and examine the contributions of potential drivers. Our results show that forest composition is the key factor influencing the spatial variations of fire mortality across ecoregions. For the temporal variations, we find that the late-season burning was associated with higher fire intensity, which lead to greater forest mortality than the early-season burning. Forests burned in the warm and dry years had greater mortality than those burned in the cool and wet years. Our findings suggest that climate warming and drying not only stimulated boreal fire frequency, but also enhanced fire severity and forest mortality. Due to the significant effects of forest mortality on vegetation structure and ecosystem carbon dynamics, the spatiotemporal changes of fire-induced forest mortality should be explicitly considered to better understand fire impacts on regional and global climate change.

Bending the carbon curve: fire management for carbon resilience under climate change

Treesearch

E. L. Loudermilk; R. M. Scheller; P. J. Weisberg; Alec Kretchun

2017-01-01

Forest landscapes are increasingly managed for fire resilience, particularly in the western US which has recently experienced drought and widespread, high-severity wildfires. Fuel reduction treatments have been effective where fires coincide with treated areas. Fuel treatments also have the potential to reduce drought-mortality if tree density is...

Leaving moss and litter layers undisturbed reduces the short-term environmental consequences of heathland managed burns.

PubMed

Grau-Andrés, Roger; Davies, G Matt; Waldron, Susan; Scott, E Marian; Gray, Alan

2017-12-15

Variation in the structure of ground fuels, i.e. the moss and litter (M/L) layer, may be an important control on fire severity in heather moorlands and thus influence vegetation regeneration and soil carbon dynamics. We completed experimental fires in a Calluna vulgaris-dominated heathland to study the role of the M/L layer in determining (i) fire-induced temperature pulses into the soil and (ii) post-fire soil thermal dynamics. Manually removing the M/L layer before burning increased fire-induced soil heating, both at the soil surface and 2 cm below. Burnt plots where the M/L layer was removed simulated the fuel structure after high severity fires where ground fuels are consumed but the soil does not ignite. Where the M/L layer was manually removed, either before or after the fire, post-fire soil thermal dynamics showed larger diurnal and seasonal variation, as well as similar patterns to those observed after wildfires, compared to burnt plots where the M/L layer was not manipulated. We used soil temperatures to explore potential changes in post-fire soil respiration. Simulated high fire severity (where the M/L layer was manually removed) increased estimates of soil respiration in warm months. With projected fire regimes shifting towards higher severity fires, our results can help land managers develop strategies to balance ecosystem services in Calluna-dominated habitats. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Comparison of AVIRIS and Landsat ETM+ detection capabilities for burn severity

USGS Publications Warehouse

Van Wagtendonk, Jan W.; Root, Ralph R.; Key, Carl H.

2004-01-01

Our study compares data on burn severity collected from multi-temporal Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) with similar data from the Enhanced Thematic Mapper Plus (ETM+) using the differenced Normalized Burn Ratio (dNBR). Two AVIRIS and ETM+ data acquisitions recorded surface conditions immediately before the Hoover Fire began to spread rapidly and again the following year. Data were validated with 63 field plots using the Composite Burn Index (CBI). The relationship between spectral channels and burn severity was examined by comparing pre- and post-fire datasets. Based on the high burn severity comparison, AVIRIS channels 47 and 60 at wavelengths of 788 and 913 nm showed the greatest negative response to fire. Post-fire reflectance values decreased the most on average at those wavelengths, while channel 210 at 2370 nm showed the greatest positive response on average. Fire increased reflectance the most at that wavelength over the entire measured spectral range. Furthermore, channel 210 at 2370 nm exhibited the greatest variation in spectral response, suggesting potentially high information content for fire severity. Based on general remote sensing principles and the logic of variable spectral responses to fire, dNBR from both sensors should produce useful results in quantifying burn severity. The results verify the band–response relationships to burn severity as seen with ETM+ data and confirm the relationships by way of a distinctly different sensor system.

Forecasting distribution of numbers of large fires

USGS Publications Warehouse

Eidenshink, Jeffery C.; Preisler, Haiganoush K.; Howard, Stephen; Burgan, Robert E.

2014-01-01

Systems to estimate forest fire potential commonly utilize one or more indexes that relate to expected fire behavior; however they indicate neither the chance that a large fire will occur, nor the expected number of large fires. That is, they do not quantify the probabilistic nature of fire danger. In this work we use large fire occurrence information from the Monitoring Trends in Burn Severity project, and satellite and surface observations of fuel conditions in the form of the Fire Potential Index, to estimate two aspects of fire danger: 1) the probability that a 1 acre ignition will result in a 100+ acre fire, and 2) the probabilities of having at least 1, 2, 3, or 4 large fires within a Predictive Services Area in the forthcoming week. These statistical processes are the main thrust of the paper and are used to produce two daily national forecasts that are available from the U.S. Geological Survey, Earth Resources Observation and Science Center and via the Wildland Fire Assessment System. A validation study of our forecasts for the 2013 fire season demonstrated good agreement between observed and forecasted values.

Mapping the potential for high severity wildfire in the western United States

Treesearch

Greg Dillon; Penny Morgan; Zack Holden

2011-01-01

Each year, large areas are burned in wildfires across the Western United States. Assessing the ecological effects of these fires is crucial to effective postfire management. This requires accurate, efficient, and economical methods to assess the severity of fires at broad landscape scales (Brennan and Hardwick 1999; Parsons and others 2010). While postfire assessment...

An evaluation of three wood shred blends for post-fire erosion control using indoor simulated rain events on small plots

Treesearch

R. B. Foltz; N. S. Wagenbrenner

2010-01-01

The assessment teams who make post-fire stabilization and treatment decisions are under pressure to employ more effective and economic post-fire treatments, as wild fire activity and severity has increased in recent years across the western United States. Use of forest-native wood-based materials for hillslope mulching has been on the rise due to potential...

Effects of dormant and growing season burning on surface fuels and potential fire behavior in northern Florida longleaf pine (Pinus palustris) flatwoods

Treesearch

James B. Cronan; Clinton S. Wright; Maria Petrova

2015-01-01

Prescribed fire is widely used to manage fuels in high-frequency, low-severity fire regimes including pine flatwoods of the southeastern USA where prescribed burning during the growing season (the frost-free period during the calendar year) has become more common in recent decades. Growing season prescribed fires address ecological management objectives that focus on...

Motorcoach Fire Safety Analysis.

DOT National Transportation Integrated Search

2009-07-01

This purpose of this study was to collect and analyze information from Government, industry, and media sources on the causes, frequency, and severity of motorcoach fires in the U.S., and to identify potential risk reduction measures. The Volpe Center...

Ecological and sampling constraints on defining landscape fire severity

USGS Publications Warehouse

Key, C.H.

2006-01-01

Ecological definition and detection of fire severity are influenced by factors of spatial resolution and timing. Resolution determines the aggregation of effects within a sampling unit or pixel (alpha variation), hence limiting the discernible ecological responses, and controlling the spatial patchiness of responses distributed throughout a burn (beta variation). As resolution decreases, alpha variation increases, extracting beta variation and complexity from the spatial model of the whole burn. Seasonal timing impacts the quality of radiometric data in terms of transmittance, sun angle, and potential contrast between responses within burns. Detection sensitivity candegrade toward the end of many fire seasons when low sun angles, vegetation senescence, incomplete burning, hazy conditions, or snow are common. Thus, a need exists to supersede many rapid response applications when remote sensing conditions improve. Lag timing, or timesince fire, notably shapes the ecological character of severity through first-order effects that only emerge with time after fire, including delayed survivorship and mortality. Survivorship diminishes the detected magnitude of severity, as burned vegetation remains viable and resprouts, though at first it may appear completely charred or consumed above ground. Conversely, delayed mortality increases the severity estimate when apparently healthy vegetation is in fact damaged by heat to the extent that it dies over time. Both responses dependon fire behavior and various species-specific adaptations to fire that are unique to the pre-firecomposition of each burned area. Both responses can lead initially to either over- or underestimating severity. Based on such implications, three sampling intervals for short-term burn severity are identified; rapid, initial, and extended assessment, sampled within about two weeks, two months, and depending on the ecotype, from three months to one year after fire, respectively. Spatial and temporal conditions of sampling strategies constrain data quality and ecological information obtained about fire severity. Though commonly overlooked, such considerations determine the objectives and hypotheses that are appropriate for each application, and are especially important when building comparative studies or long-term reference databases on fire severity.

Effects of multiple fires on the structure of southwestern Washington forests

Treesearch

Andrew N. Gray; Jerry F. Franklin

1997-01-01

Fire frequcncy, intensity, and size can influence the nature of forest development, with potentially profound effects on ecosystem processes and the abundance of native species. The effect of an intense wildfire and subsequent severe fires within a short period (reburns) on forest establishment, composition, and structure was examined in the 16,000 ha Siouxon Creek...

Vegetation response after post-fire mulching and native grass seeding

Treesearch

Penelope Morgan; Marshell Moy; Christine A. Droske; Leigh B. Lentile; Sarah A. Lewis; Peter R. Robichaud; Andrew T. Hudak

2014-01-01

Post-fire mulch and seeding treatments, often applied on steep, severely burned slopes immediately after large wildfires, are meant to reduce the potential of erosion and establishment of invasive plants, especially non-native plants, that could threaten values at risk. However, the effects of these treatments on native vegetation response post fire are little studied...

Ten years after wildfires: How does varying tree mortality impact fire hazard and forest resiliency?

Treesearch

Camille S. Stevens-Rumann; Carolyn H. Sieg; Molly E. Hunter

2012-01-01

Severe wildfires across the western US have lead to concerns about heavy surface fuel loading and the potential for high-intensity reburning. Ponderosa pine (Pinus ponderosa) forests, often overly dense from a century of fire suppression, are increasingly susceptible to large and severe wildfires especially given warmer and drier climate projections for the future....

Export of solids and nutrients from burnt areas: effects of fire severity and forest type

NASA Astrophysics Data System (ADS)

Abrantes, Nelson; Morais, Inês; Silva, Vera; Malvar, Mauxa C.; Prats, Sérgio; Coelho, Celeste; Keizer, Jan J.

2015-04-01

In the last few decades, the number of wildfires has markedly increased in Mediterranean Europe, including Portugal. Besides a range of direct impacts, wildfires can significantly alter the geomorphological and hydrological processes during a period commonly referred to as the "window-of-disturbance". It is now increasingly recognized that these indirect wildfire effects depend strongly on fire severity, i.e. the heating-induced changes in vegetation and litter cover as well as in topsoil properties such as infiltration capacity, aggregate stability and soil water repellency. Nonetheless, the exact role of fire severity in post-fire hydrological and erosion processes is still poorly quantified in many parts of the world, including Portugal. Another important gap in fire-related research stills to be the impacts of wildfire on soil fertility losses, in particular through erosion by runoff. Both research gaps were addressed in this study, following a wildfire that took place in July 2013 in Talhadas (Sever do Vouga, Aveiro) and burnt circa 815 ha. In the burnt area and the surrounding unburnt areas, six study sites were selected and, immediately after the fire, instrumented with slope-scale runoff plots. Two of the sites were long-unburnt, two were burnt at low severity and the other two were burnt at high severity; for all of them one being covered by a Eucalyptus globulus plantation and the other by a Pinus pinaster plantation. Following the instrumentation of the sites, runoff was measured at 1- to 2-weekly intervals and, whenever possible, runoff samples were collected for subsequent analysis in the laboratory with respect to total suspended sediments content and total nitrogen and total phosphorus concentrations. The results obtained in this study showed that the severity of the fire played a more important role in the loss of nutrients and solids than the type of vegetation. While the occurrence of fire markedly increased soil (fertility) losses, this effect was much stronger following a high-severity than low-severity fire. In the case of the pine slope, this effect of fire severity could be attributed to post-fire pine needle cast, with pine needles being scorched by the low-severity fire and being combusted in the high-severity fire. Looking at the temporal evolution, for both pine and eucalyptus slopes, significant exportations of solids as well nutrients were still found 10 months after the fire occurrence (May 2014) . This study highlight the importance of wildfire as a driver for the soil and fertility loss with consequent/potential impacts on surface water quality.

Fuel type characterization and potential fire behavior estimation in Sardinia and Corsica islands

NASA Astrophysics Data System (ADS)

Bacciu, V.; Pellizzaro, G.; Santoni, P.; Arca, B.; Ventura, A.; Salis, M.; Barboni, T.; Leroy, V.; Cancellieri, D.; Leoni, E.; Ferrat, L.; Perez, Y.; Duce, P.; Spano, D.

2012-04-01

Wildland fires represent a serious threat to forests and wooded areas of the Mediterranean Basin. As recorded by the European Commission (2009), during the last decade Southern Countries have experienced an annual average of about 50,000 forest fires and about 470,000 burned hectares. The factor that can be directly manipulated in order to minimize fire intensity and reduce other fire impacts, such as three mortality, smoke emission, and soil erosion, is wildland fuel. Fuel characteristics, such as vegetation cover, type, humidity status, and biomass and necromass loading are critical variables in affecting wildland fire occurrence, contributing to the spread, intensity, and severity of fires. Therefore, the availability of accurate fuel data at different spatial and temporal scales is needed for fire management applications, including fire behavior and danger prediction, fire fighting, fire effects simulation, and ecosystem simulation modeling. In this context, the main aims of our work are to describe the vegetation parameters involved in combustion processes and develop fire behavior fuel maps. The overall work plan is based firstly on the identification and description of the different fuel types mainly affected by fire occurrence in Sardinia (Italy) and Corsica (France) Islands, and secondly on the clusterization of the selected fuel types in relation to their potential fire behavior. In the first part of the work, the available time series of fire event perimeters and the land use map data were analyzed with the purpose of identifying the main land use types affected by fires. Thus, field sampling sites were randomly identified on the selected vegetation types and several fuel variables were collected (live and dead fuel load partitioned following Deeming et al., (1977), depth of fuel layer, plant cover, surface area-to-volume ratio, heat content). In the second part of the work, the potential fire behavior for every experimental site was simulated using BEHAVE fire behavior prediction system (Andrews, 1989) and experimental fuel data. Fire behavior was simulated by setting different weather scenarios representing the most frequent summer meteorological conditions. The simulation outputs (fireline intensity, rate of spread, flame length) were then analyzed for clustering the different fuel types in relation to their potential fire behavior. The results of this analysis can be used to produce fire behavior fuel maps that are important tools in evaluating fire hazard and risk for land management planning, locating and rating fuel treatments, and aiding in environmental assessments and fire danger programs modeling. This work is supported by FUME Project FP7-ENV-2009-1, Grant Agreement Number 243888 and Proterina-C Project, EU Italia-Francia Marittimo 2007-2013 Programme.

Shrub removal in reforested post-fire areas increases native plant species richness

Treesearch

Gabrielle N. Bohlman; Malcolm North; Hugh D. Safford

2016-01-01

Large, high severity fires are becoming more prevalent in Sierra Nevada mixed-conifer forests, largely due to heavy fuel loading and forest densification caused by past and current management practices. In post-fire areas distant from seed trees, conifers are often planted to re-establish a forest and to prevent a potential type-conversion to shrub fields. Typical...

Prescribed fire applications in Forest and Woodlands: Integration of models and field studies to guide fire use

Treesearch

Kevin C. Ryan; Eric Rigolot; Francisco C. Rego; Herminio Botelho; Jose A. Vega; Paulo M. Fernandes; Tatiana M. Sofronova

2010-01-01

Globally prescribed burning is widely used for agro-forestry, restoration, and conservation to modify species composition and stand structure. Commonly stated goals of prescribed burns include to reduce hazardous fuels, improve species’ habitat, reduce the potential for severe fires in the wildland urban interface or protect municipal watersheds. Treatments may focus...

Fire treatment effects on vegetation structure, fuels, and potential fire severity in western U.S. forests

Treesearch

Scott L. Stephens; Jason J. Moghaddas; Carl Edminster; Carl E. Fiedler; Sally Haase; Michael Harrington; Jon E. Keeley; Eric E. Knapp; James D. McIver; Kerry Metlen; Carl N. Skinner; Andrew Youngblood

2009-01-01

Forest structure and species composition in many western U.S. coniferous forests have been altered through fire exclusion, past and ongoing harvesting practices, and livestock grazing over the 20th century. The effects of these activities have been most pronounced in seasonally dry, low and mid-elevation coniferous forests that once experienced frequent, low to...

Comparing the effectiveness of thinning and prescribed fire for modifying structure in dry coniferous forests

Treesearch

Richy J. Harrod; Nicholas A. Povak; David W. Peterson

2007-01-01

Forest thinning and prescribed fires are the main practices used by managers to address concerns over ecosystem degradation and severe wildland fire potential in dry forests of the Western United States. There is some debate, however, about treatment effectiveness in meeting management objectives as well as their ecological consequences. This study assesses the...

Remote sensing sensitivity to fire severity and fire recovery

USGS Publications Warehouse

Key, C.H.

2005-01-01

The paper examines fundamental ways that geospatial data on fire severity and recovery are influenced by conditions of the remote sensing. Remote sensing sensitivities are spatial, temporal and radiometric in origin. Those discussed include spatial resolution, the sampling time of year, and time since fire. For standard reference, sensitivities are demonstrated with examples drawn from an archive of burn assessments based on one radiometric index, the differenced Normalized Burn Ratio. Resolution determines the aggregation of fire effects within a pixel (alpha variation), hence defining the detected ecological response, and controlling the ability to determine patchiness and spatial distribution of responses throughout a burn (beta variation). As resolution decreases, alpha variation increases, extracting beta variation from the complexity of the whole burn. Seasonal timing impacts the radiometric quality of data in terms of transmittance, sun angle, and potential for enhanced contrast between responses within burns. Remote sensing sensitivity can degrade during many fire seasons when snow, incomplete burning, hazy conditions, low sun angles, or extended drought are common. Time since fire (lag timing) most notably shapes severity detection through the first-order fire effects evident in survivorship and delayed mortality that emerge by the growth period after fire. The former effects appear overly severe at first, but diminish, as burned vegetation remains viable. Conversely, the latter signals vegetation that appears healthy at first, but is damaged by heat to the extent that it soon dies. Both responses can lead to either over- or under-estimating severity, respectively, depending on fire behavior and pre-fire composition unique to each burned area. Based on implications of such sensitivities, three sampling intervals for short-term burn severity are identified; rapid, initial, and extended assessment, sampled within ca. two weeks, two months, and depending on the ecotype, from three months to one year after fire, respectively. Jointly, remote sensing conditions and the way burns are studied yield different tendencies for data quality and information content that impact the objectives and hypotheses that can be studied. Such considerations can be commonly overlooked, but need to be incorporated especially in comparative studies, and to build long-term reference databases on fire severity and recovery.

Developing Custom Fire Behavior Fuel Models for Mediterranean Wildland-Urban Interfaces in Southern Italy

NASA Astrophysics Data System (ADS)

Elia, Mario; Lafortezza, Raffaele; Lovreglio, Raffaella; Sanesi, Giovanni

2015-09-01

The dramatic increase of fire hazard in wildland-urban interfaces (WUIs) has required more detailed fuel management programs to preserve ecosystem functions and human settlements. Designing effective fuel treatment strategies allows to achieve goals such as resilient landscapes, fire-adapted communities, and ecosystem response. Therefore, obtaining background information on forest fuel parameters and fuel accumulation patterns has become an important first step in planning fuel management interventions. Site-specific fuel inventory data enhance the accuracy of fuel management planning and help forest managers in fuel management decision-making. We have customized four fuel models for WUIs in southern Italy, starting from forest classes of land-cover use and adopting a hierarchical clustering approach. Furthermore, we provide a prediction of the potential fire behavior of our customized fuel models using FlamMap 5 under different weather conditions. The results suggest that fuel model IIIP (Mediterranean maquis) has the most severe fire potential for the 95th percentile weather conditions and the least severe potential fire behavior for the 85th percentile weather conditions. This study shows that it is possible to create customized fuel models directly from fuel inventory data. This achievement has broad implications for land managers, particularly forest managers of the Mediterranean landscape, an ecosystem that is susceptible not only to wildfires but also to the increasing human population and man-made infrastructures.

Developing Custom Fire Behavior Fuel Models for Mediterranean Wildland-Urban Interfaces in Southern Italy.

PubMed

Elia, Mario; Lafortezza, Raffaele; Lovreglio, Raffaella; Sanesi, Giovanni

2015-09-01

The dramatic increase of fire hazard in wildland-urban interfaces (WUIs) has required more detailed fuel management programs to preserve ecosystem functions and human settlements. Designing effective fuel treatment strategies allows to achieve goals such as resilient landscapes, fire-adapted communities, and ecosystem response. Therefore, obtaining background information on forest fuel parameters and fuel accumulation patterns has become an important first step in planning fuel management interventions. Site-specific fuel inventory data enhance the accuracy of fuel management planning and help forest managers in fuel management decision-making. We have customized four fuel models for WUIs in southern Italy, starting from forest classes of land-cover use and adopting a hierarchical clustering approach. Furthermore, we provide a prediction of the potential fire behavior of our customized fuel models using FlamMap 5 under different weather conditions. The results suggest that fuel model IIIP (Mediterranean maquis) has the most severe fire potential for the 95th percentile weather conditions and the least severe potential fire behavior for the 85th percentile weather conditions. This study shows that it is possible to create customized fuel models directly from fuel inventory data. This achievement has broad implications for land managers, particularly forest managers of the Mediterranean landscape, an ecosystem that is susceptible not only to wildfires but also to the increasing human population and man-made infrastructures.

MERCURY CONTROL IN MUNICIPAL WASTE COMBUSTORS AND COAL-FIRED UTILITIES

EPA Science Inventory

Control of mercury (Hg) emissions from municipal waste combustors (MWCs) and coal-fired utilities has attracted attention due to current and potential regulations. Among several techniques evaluated for Hg control, dry sorbent injection (primarily injection of activated carbon) h...

Fire Effects on Microbial Enzyme Activities in Larch Forests of the Siberian Arctic

NASA Astrophysics Data System (ADS)

Ludwig, S.; Alexander, H. D.; Bulygina, E. B.; Mann, P. J.; Natali, S.

2012-12-01

Arctic forest ecosystems are warming at an accelerated rate relative to lower latitudes, with global implications for C cycling within these regions. As climate continues to warm and dry, wildfire frequency and severity are predicted to increase, creating a positive feedback to climate warming. Increased fire activity will also influence the microenvironment experienced by soil microbes in disturbed soils. Because soil microbes regulate carbon (C) and nitrogen (N) cycling between terrestrial ecosystems and the atmosphere, it is important to understand microbial response to fires, particularly in the understudied larch forests in the Siberian Arctic. In this project, we created experimental burn plots in a mature larch forest in the Kolyma River watershed of Northeastern Siberia. Plots were burned at several treatments: control (no burn), low, moderate, and severe. After, 1 and 8 d post-fire, we measured soil organic layer depth, soil organic matter (SOM) content, soil moisture, and CO2 flux from the plots. Additionally, we leached soils and measured dissolved organic carbon (DOC), total dissolved nitrogen (TDN), NH4, NO3, soluble reactive phosphorus (SRP), and chromophoric dissolved organic matter (CDOM). Furthermore, we measured extracellular activity of four enzymes involved in soil C and nutrient cycling (leucine aminopeptidase (LAP), β-glucosidase, phosphatase, and phenol oxidase). One day post-fire, LAP activity was similarly low in all treatments, but by 8 d post-fire, LAP activity was lower in burned plots compared to control plots, likely due to increased nitrogen content with increasing burn severity. Phosphatase activity decreased with burn severity 1 d post-fire, but after 8 d, moderate and severe burn plots exhibited increased phosphatase activity. Coupled with trends in LAP activity, this suggests a switch in nutrient limitation from N to phosphorus that is more pronounced with burn severity. β-glucosidase activity similarly decreased with burn severity 1 d post-fire, but by 8 d post-fire activity was the same in all treatments, indicating complete recovery of the microbial population. Phenol oxidase activity was low in all treatments 1 d post-fire, but by 8 d post-fire, severe plots had substantially increased phenol oxidase activity, likely due to microbial efforts to mitigate phenolic compound toxicity following severe fires. Both DOC and the slope ratio of CDOM absorbance increased with burn severity 1 d post-fire, indicating higher extractability of lighter molecular weight C from severe burns. These results imply that black C created from fires remains as a stable C pool while more labile C is mobilized with increasing burn severity. Our results suggest that the immediate effects of fire severity on microbial communities have the potential to change both nutrient use and the form and concentration of C being processed and mobilized from larch forest ecosystems. These findings highlight the importance of changing fire regimes on soil dynamics with implications for forest re-growth, soil-atmospheric feedbacks, and terrestrial inputs to aquatic ecosystems.

Real time forest fire warning and forest fire risk zoning: a Vietnamese case study

NASA Astrophysics Data System (ADS)

Chu, T.; Pham, D.; Phung, T.; Ha, A.; Paschke, M.

2016-12-01

Forest fire occurs seriously in Vietnam and has been considered as one of the major causes of forest lost and degradation. Several studies of forest fire risk warning were conducted using Modified Nesterov Index (MNI) but remaining shortcomings and inaccurate predictions that needs to be urgently improved. In our study, several important topographic and social factors such as aspect, slope, elevation, distance to residential areas and road system were considered as "permanent" factors while meteorological data were updated hourly using near-real-time (NRT) remotely sensed data (i.e. MODIS Terra/Aqua and TRMM) for the prediction and warning of fire. Due to the limited number of weather stations in Vietnam, data from all active stations (i.e. 178) were used with the satellite data to calibrate and upscale meteorological variables. These data with finer resolution were then used to generate MNI. The only significant "permanent" factors were selected as input variables based on the correlation coefficients that computed from multi-variable regression among true fire-burning (collected from 1/2007) and its spatial characteristics. These coefficients also used to suggest appropriate weight for computing forest fire risk (FR) model. Forest fire risk model was calculated from the MNI and the selected factors using fuzzy regression models (FRMs) and GIS based multi-criteria analysis. By this approach, the FR was slightly modified from MNI by the integrated use of various factors in our fire warning and prediction model. Multifactor-based maps of forest fire risk zone were generated from classifying FR into three potential danger levels. Fire risk maps were displayed using webgis technology that is easy for managing data and extracting reports. Reported fire-burnings thereafter have been used as true values for validating the forest fire risk. Fire probability has strong relationship with potential danger levels (varied from 5.3% to 53.8%) indicating that the higher potential risk, the more chance of fire happen. By adding spatial factors to continuous daily updated remote sensing based meteo-data, results are valuable for both mapping forest fire risk zones in short and long-term and real time fire warning in Vietnam. Key words: Near-real-time, forest fire warning, fuzzy regression model, remote sensing.

Quantifying the Causes and Propogation of the 2015 Washington Wildfires

NASA Astrophysics Data System (ADS)

Engel, R.; Marlier, M. E.; Lettenmaier, D. P.

2017-12-01

In the summer of 2015, Washington state experienced wildfires that burned over 450,000 ha, more than five times the average and more than three times the next-most severe fire season in the 30-year record. We examine the confluence of factors that led to the extreme fire season, and evaluate whether 2015 can be used as a predictor of possible future conditions that will be affected by climate warming. In previous work, we have found that 2015 was an extremely warm summer (nearly 1 degree C warmer than the previous year in the 30-year record) but was not particularly anomalous in terms of many other climatic indicators, including reconstructed soil moisture, the Palmer Drought Severity Index (PDSI), and the Canadian Fire Weather Index. However, according to the Dead Fuel Moisture (DFM), a drying index used by the US Forest Service, 2015 was an extreme year of record. The DFM relies on temperature, precipitation, and relative humidity to establish a daily equilibrium moisture content of dead material. We examine both Washington's 2015 fire season and the 30-year fire record with respect to climatology and other potential drivers of fire (e.g. forest health, ignition). Additionally, we explore the role of land cover with respect to fire propagation through the season. While too many potential causes of extreme fires exist to establish a concrete long-term relationship at such a fine scale, we find that the 2015 fire anomaly was at least partially climatically driven.

Corrosion of Aluminum Alloys in the Presence of Fire-Retardant Aircraft Interior Materials

DOT National Transportation Integrated Search

1995-10-01

This research project was to evaluate the potential for fire-retardant materials used in aircraft interiors to cause corrosion of aluminum structural alloys. Service Difficulty Reports (SDR's) were reviewed for several aircraft types, and the most fr...

Seasonal forecasting of fire over Kalimantan, Indonesia

NASA Astrophysics Data System (ADS)

Spessa, A. C.; Field, R. D.; Pappenberger, F.; Langner, A.; Englhart, S.; Weber, U.; Stockdale, T.; Siegert, F.; Kaiser, J. W.; Moore, J.

2015-03-01

Large-scale fires occur frequently across Indonesia, particularly in the southern region of Kalimantan and eastern Sumatra. They have considerable impacts on carbon emissions, haze production, biodiversity, health, and economic activities. In this study, we demonstrate that severe fire and haze events in Indonesia can generally be predicted months in advance using predictions of seasonal rainfall from the ECMWF System 4 coupled ocean-atmosphere model. Based on analyses of long, up-to-date series observations on burnt area, rainfall, and tree cover, we demonstrate that fire activity is negatively correlated with rainfall and is positively associated with deforestation in Indonesia. There is a contrast between the southern region of Kalimantan (high fire activity, high tree cover loss, and strong non-linear correlation between observed rainfall and fire) and the central region of Kalimantan (low fire activity, low tree cover loss, and weak, non-linear correlation between observed rainfall and fire). The ECMWF seasonal forecast provides skilled forecasts of burnt and fire-affected area with several months lead time explaining at least 70% of the variance between rainfall and burnt and fire-affected area. Results are strongly influenced by El Niño years which show a consistent positive bias. Overall, our findings point to a high potential for using a more physical-based method for predicting fires with several months lead time in the tropics rather than one based on indexes only. We argue that seasonal precipitation forecasts should be central to Indonesia's evolving fire management policy.

Thinning and prescribed fire effects on overstory tree and snag structure in dry coniferous forests of the interior Pacific Northwest

Treesearch

Richy J. Harrod; David W. Peterson; Nicholas A. Povak; Erich Kyle Dodson

2009-01-01

Forest thinning and prescribed fires are practices used by managers to address concerns over ecosystem degradation and severe wildland fire potential in dry forests. There is some debate, however, about treatment effectiveness in meeting management objectives as well as their ecological consequences. The purpose of this study was to assess changes to forest stand...

Western spruce budworm outbreaks did not increase fire risk over the last three centuries: A dendrochronological analysis of inter-disturbance synergism

Treesearch

Aquila Flower; Daniel G. Gavin; Emily K. Heyerdahl; Russell A. Parsons; Gregory M. Cohn

2014-01-01

Insect outbreaks are often assumed to increase the severity or probability of fire occurrence through increased fuel availability, while fires may in turn alter susceptibility of forests to subsequent insect outbreaks through changes in the spatial distribution of suitable host trees. However, little is actually known about the potential synergisms between these...

Long-term overstory and understory change following logging and fire exclusion in a Sierra Nevada mixed-conifer forest

Treesearch

Eric E. Knapp; Carl N. Skinner; Malcolm P. North; Becky L. Estes

2013-01-01

In many forests of the western US, increased potential for fires of uncharacteristic intensity and severity is frequently attributed to structural changes brought about by fire exclusion, past land management practices, and climate. Extent of forest change and effect on understory vegetation over time are not well understood, but such information is useful to forest...

Alternative approach for fire suppression of class A, B and C fires in gloveboxes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenberger, Mark S; Tsiagkouris, James A

2011-02-10

Department of Energy (DOE) Orders and National Fire Protection Association (NFPA) Codes and Standards require fire suppression in gloveboxes. Several potential solutions have been and are currently being considered at Los Alamos National Laboratory (LANL). The objective is to provide reliable, minimally invasive, and seismically robust fire suppression capable of extinguishing Class A, B, and C fires; achieve compliance with DOE and NFPA requirements; and provide value-added improvements to fire safety in gloveboxes. This report provides a brief summary of current approaches and also documents the successful fire tests conducted to prove that one approach, specifically Fire Foe{trademark} tubes, ismore » capable of achieving the requirement to provide reliable fire protection in gloveboxes in a cost-effective manner.« less

Regional variation in fire weather controls the reported occurrence of Scottish wildfires

PubMed Central

Legg, Colin J.

2016-01-01

Fire is widely used as a traditional habitat management tool in Scotland, but wildfires pose a significant and growing threat. The financial costs of fighting wildfires are significant and severe wildfires can have substantial environmental impacts. Due to the intermittent occurrence of severe fire seasons, Scotland, and the UK as a whole, remain somewhat unprepared. Scotland currently lacks any form of Fire Danger Rating system that could inform managers and the Fire and Rescue Services (FRS) of periods when there is a risk of increased of fire activity. We aimed evaluate the potential to use outputs from the Canadian Fire Weather Index system (FWI system) to forecast periods of increased fire risk and the potential for ignitions to turn into large wildfires. We collated four and a half years of wildfire data from the Scottish FRS and examined patterns in wildfire occurrence within different regions, seasons, between urban and rural locations and according to FWI system outputs. We used a variety of techniques, including Mahalanobis distances, percentile analysis and Thiel-Sen regression, to scope the best performing FWI system codes and indices. Logistic regression showed significant differences in fire activity between regions, seasons and between urban and rural locations. The Fine Fuel Moisture Code and the Initial Spread Index did a tolerable job of modelling the probability of fire occurrence but further research on fuel moisture dynamics may provide substantial improvements. Overall our results suggest it would be prudent to ready resources and avoid managed burning when FFMC > 75 and/or ISI > 2. PMID:27833814

Regional variation in fire weather controls the reported occurrence of Scottish wildfires.

PubMed

Davies, G Matt; Legg, Colin J

2016-01-01

Fire is widely used as a traditional habitat management tool in Scotland, but wildfires pose a significant and growing threat. The financial costs of fighting wildfires are significant and severe wildfires can have substantial environmental impacts. Due to the intermittent occurrence of severe fire seasons, Scotland, and the UK as a whole, remain somewhat unprepared. Scotland currently lacks any form of Fire Danger Rating system that could inform managers and the Fire and Rescue Services (FRS) of periods when there is a risk of increased of fire activity. We aimed evaluate the potential to use outputs from the Canadian Fire Weather Index system (FWI system) to forecast periods of increased fire risk and the potential for ignitions to turn into large wildfires. We collated four and a half years of wildfire data from the Scottish FRS and examined patterns in wildfire occurrence within different regions, seasons, between urban and rural locations and according to FWI system outputs. We used a variety of techniques, including Mahalanobis distances, percentile analysis and Thiel-Sen regression, to scope the best performing FWI system codes and indices. Logistic regression showed significant differences in fire activity between regions, seasons and between urban and rural locations. The Fine Fuel Moisture Code and the Initial Spread Index did a tolerable job of modelling the probability of fire occurrence but further research on fuel moisture dynamics may provide substantial improvements. Overall our results suggest it would be prudent to ready resources and avoid managed burning when FFMC > 75 and/or ISI > 2.

Index for characterizing post-fire soil environments in temperate coniferous forests

USGS Publications Warehouse

Jain, Theresa B.; Pilliod, David S.; Graham, Russell T.; Lentile, Leigh B.; Sandquist, Jonathan E.

2012-01-01

Many scientists and managers have an interest in describing the environment following a fire to understand the effects on soil productivity, vegetation growth, and wildlife habitat, but little research has focused on the scientific rationale for classifying the post-fire environment. We developed an empirically-grounded soil post-fire index (PFI) based on available science and ecological thresholds. Using over 50 literature sources, we identified a minimum of five broad categories of post-fire outcomes: (a) unburned, (b) abundant surface organic matter ( > 85% surface organic matter), (c) moderate amount of surface organic matter ( ≥ 40 through 85%), (d) small amounts of surface organic matter ( < 40%), and (e) absence of surface organic matter (no organic matter left). We then subdivided each broad category on the basis of post-fire mineral soil colors providing a more fine-tuned post-fire soil index. We related each PFI category to characteristics such as soil temperature and duration of heating during fire, and physical, chemical, and biological responses. Classifying or describing post-fire soil conditions consistently will improve interpretations of fire effects research and facilitate communication of potential responses or outcomes (e.g., erosion potential) from fires of varying severities.

Assessment of fire severity and species diversity in the southern Appalachians using Landsat TM and ETM+ imagery

Treesearch

Michael C. Wimberly; Matthew J. Reilly

2007-01-01

Relatively little is known about the disturbance ecology of large wildfires in the southern Appalachians. The occurrence of a 4000-ha wildfire in the Linville Gorge Wilderness area in western North Carolina has provided a rare opportunity to study a large fire with a range of severities. The objectives of this study were to 1) assess the potential for using multi-...

Water contamination risks associated with a combination of planned and unplanned fire in south eastern Australia

NASA Astrophysics Data System (ADS)

Sheridan, G. J.; Nyman, P.; Langhans, C.; Noske, P. J.; Lane, P. N. J.

2014-12-01

Planned burning reduces fuel loads in forests, potentially reducing the severity of subsequent wildfires. However planned burning also increases the risk of a significant water quality impact by maintaining a proportion of the catchment in a burnt condition conducive to generating high magnitude erosion events (eg. debris flows). Differences in the frequency and magnitude of planned and unplanned fire, combined with poorly understood relationships between fire severity and hydrologic impacts, means that predictions of the net water contamination risks associated with any particular fire regime are difficult to predict. This presentation synthesises results from 10 years of point, plot and catchment-scale post-fire hydrology and erosion studies in SE Australia to estimate the likely benifits and risks of planned burning scenarios from a drinking water supply perspective

Estimation of wildfire size and risk changes due to fuels treatments

USGS Publications Warehouse

Cochrane, M.A.; Moran, C.J.; Wimberly, M.C.; Baer, A.D.; Finney, M.A.; Beckendorf, K.L.; Eidenshink, J.; Zhu, Z.

2012-01-01

Human land use practices, altered climates, and shifting forest and fire management policies have increased the frequency of large wildfires several-fold. Mitigation of potential fire behaviour and fire severity have increasingly been attempted through pre-fire alteration of wildland fuels using mechanical treatments and prescribed fires. Despite annual treatment of more than a million hectares of land, quantitative assessments of the effectiveness of existing fuel treatments at reducing the size of actual wildfires or how they might alter the risk of burning across landscapes are currently lacking. Here, we present a method for estimating spatial probabilities of burning as a function of extant fuels treatments for any wildland fire-affected landscape. We examined the landscape effects of more than 72 000 ha of wildland fuel treatments involved in 14 large wildfires that burned 314 000 ha of forests in nine US states between 2002 and 2010. Fuels treatments altered the probability of fire occurrence both positively and negatively across landscapes, effectively redistributing fire risk by changing surface fire spread rates and reducing the likelihood of crowning behaviour. Trade offs are created between formation of large areas with low probabilities of increased burning and smaller, well-defined regions with reduced fire risk.

Climate change and forest fires.

PubMed

Flannigan, M D; Stocks, B J; Wotton, B M

2000-11-15

This paper addresses the impacts of climate change on forest fires and describes how this, in turn, will impact on the forests of the United States. In addition to reviewing existing studies on climate change and forest fires we have used two transient general circulation models (GCMs), namely the Hadley Centre and the Canadian GCMs, to estimate fire season severity in the middle of the next century. Ratios of 2 x CO2 seasonal severity rating (SSR) over present day SSR were calculated for the means and maximums for North America. The results suggest that the SSR will increase by 10-50% over most of North America; although, there are regions of little change or where the SSR may decrease by the middle of the next century. Increased SSRs should translate into increased forest fire activity. Thus, forest fires could be viewed as an agent of change for US forests as the fire regime will respond rapidly to climate warming. This change in the fire regime has the potential to overshadow the direct effects of climate change on species distribution and migration.

Establishment of non-native plant species after wildfires: Effects of fuel treatments, abiotic and biotic factors, and post-fire grass seeding treatments

USGS Publications Warehouse

Hunter, M.E.; Omi, Philip N.; Martinson, E.J.; Chong, G.W.

2006-01-01

Establishment and spread of non-native species following wildfires can pose threats to long-term native plant recovery. Factors such as disturbance severity, resource availability, and propagule pressure may influence where non-native species establish in burned areas. In addition, pre- and post-fire management activities may influence the likelihood of non-native species establishment. In the present study we examine the establishment of non-native species after wildfires in relation to native species richness, fire severity, dominant native plant cover, resource availability, and pre- and post-fire management actions (fuel treatments and post-fire rehabilitation treatments). We used an information-theoretic approach to compare alternative hypotheses. We analysed post-fire effects at multiple scales at three wildfires in Colorado and New Mexico. For large and small spatial scales at all fires, fire severity was the most consistent predictor of non-native species cover. Non-native species cover was also correlated with high native species richness, low native dominant species cover, and high seeded grass cover. There was a positive, but non-significant, association of non-native species with fuel-treated areas at one wildfire. While there may be some potential for fuels treatments to promote non-native species establishment, wildfire and post-fire seeding treatments seem to have a larger impact on non-native species. ?? IAWF 2006.

Investigation of UF/sub 6/ behavior in a fire

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, W.R.

Reactions between UF/sub 6/ and combustible gases and the potential for UF/sub 6/-filled cylinders to rupture when exposed to fire are addressed. Although the absence of kinetic data prevents specific identification and quantification of the chemical species formed, potential reaction products resulting from the release of UF/sub 6/ into a fire include UF/sub 4/, UO/sub 2/F/sub 2/, HF, C, CF/sub 4/,COF/sub 2/, and short chain, fluorinated or partially fluorinated hydrocarbons. Such a release adds energy to a fire relative to normal combustion reactions. Time intervals to an assumed point of rupture for UF/sub 6/-filled cylinders exposed to fire are estimatedmore » conservatively. Several related studies are also summarized, including a test series in which small UF/sub 6/-filled cylinders were immersed in fire resulting in valve failures and explosive ruptures. It is concluded that all sizes of UF/sub 6/ cylinders currently in use may rupture within 30 minutes when totally immersed in a fire. For cylinders adjacent to fires, rupture of the larger cylinders appears much less likely.« less

High severity experimental burns in Siberian larch forests increase permafrost thaw and larch tree regeneration

NASA Astrophysics Data System (ADS)

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

2013-12-01

Global change models predict increased fire activity in boreal forests as climate warms and dries. We hypothesized that fire-driven decreases in soil organic layer (SOL) depth will (1) increase permafrost thaw by reducing the insulating capacity of the SOL and (2) improve seedbed conditions for tree regeneration. Over time, these changes will lead to altered patterns of above- and belowground carbon (C) accumulation. To test these hypotheses, we conducted plot-level experimental burns in July 2012 in a low-density, mature larch stand near the Northeast Science Station in Cherskii, Siberia. Dried fuels of naturally occurring vegetation were added to plots to achieve four burn severity treatments based on residual SOL depths: control, low (> 8 cm), moderate (5-8 cm), and high severity (2-5 cm). Pre-fire and during two growing seasons post-fire, we measured thaw depth, soil moisture, and soil temperature to determine severity effects on permafrost thaw. We also sowed larch seeds in fall 2012 and quantified germination rates the following growing season. By 1 wk post-fire, thaw depth was 15-25 cm deeper in plots burned at high severity (55 cm) compared to other treatments (30-40 cm). These differences in thaw depth with burn severity were maintained during the subsequent growing season and were associated with increased soil temperature and moisture. Larch regeneration was 10x higher on severely burned plots than those unburned. Our findings highlight the potential for increased fire severity to degrade permafrost and alter successional dynamics and patterns of C accumulation.

Interactive effects of historical logging and fire exclusion on ponderosa pine forest structure in the northern Rockies.

PubMed

Naficy, Cameron; Sala, Anna; Keeling, Eric G; Graham, Jon; DeLuca, Thomas H

2010-10-01

Increased forest density resulting from decades of fire exclusion is often perceived as the leading cause of historically aberrant, severe, contemporary wildfires and insect outbreaks documented in some fire-prone forests of the western United States. Based on this notion, current U.S. forest policy directs managers to reduce stand density and restore historical conditions in fire-excluded forests to help minimize high-severity disturbances. Historical logging, however, has also caused widespread change in forest vegetation conditions, but its long-term effects on vegetation structure and composition have never been adequately quantified. We document that fire-excluded ponderosa pine forests of the northern Rocky Mountains logged prior to 1960 have much higher average stand density, greater homogeneity of stand structure, more standing dead trees and increased abundance of fire-intolerant trees than paired fire-excluded, unlogged counterparts. Notably, the magnitude of the interactive effect of fire exclusion and historical logging substantially exceeds the effects of fire exclusion alone. These differences suggest that historically logged sites are more prone to severe wildfires and insect outbreaks than unlogged, fire-excluded forests and should be considered a high priority for fuels reduction treatments. Furthermore, we propose that ponderosa pine forests with these distinct management histories likely require distinct restoration approaches. We also highlight potential long-term risks of mechanical stand manipulation in unlogged forests and emphasize the need for a long-term view of fuels management.

Biogeochemistry and plant physiological traits interact to reinforce patterns of post-fire dominance in boreal forests

NASA Astrophysics Data System (ADS)

Shenoy, A.; Kielland, K.; Johnstone, J. F.

2011-12-01

Increases in the frequency, extent, and severity of fire in the North American boreal region are projected to continue under a warming climate and are likely to be associated with changes in future vegetation composition. In interior Alaska, fire severity is linked to the relative dominance of deciduous versus coniferous canopy species. Severely burned areas have high levels of deciduous recruitment and subsequent stand dominance, while lightly burned areas exhibit black spruce self-replacement. To elucidate potential mechanisms by which differential fire severity results in differential post-fire vegetation development, we examined changes in soil nitrogen (N) supply (NO3- and NH4+) and in situ 15N uptake by young aspen (Populus tremuloides) and black spruce (Picea mariana) trees growing in lightly and severely burned areas. We hypothesized that (a) soil nitrate supply would be higher in severely burned sites and (b) since conifers have been shown to have a reduced physiological capacity for NO3- uptake, aspen would display greater rates of NO3- uptake than spruce in severely burned sites. Our results suggested that the composition and magnitude of inorganic N supply 14 years after the fire was nearly identical in high-severity and low-severity sites, and nitrate represented nearly 50% of the supply. However, both aspen and spruce took up substantially more NH4+-N than NO3- -N regardless of fire severity. Surprisingly, spruce exhibited only a moderately lower rate of NO3- uptake (μg N/g root-1h-1) than aspen. At the stand level, aspen took up nearly an order-of-magnitude more N per hectare in severely burned sites compared to lightly burned sites, while spruce exhibited the opposite pattern of N uptake with respect to fire severity. Whereas ammonium appeared to be preferred by both species, nitrate represented a larger component of N uptake (based on the NO3-:NH4+ uptake ratio) in aspen (0.7) than in spruce (0.4). We suggest that these species-specific differences in N preference coupled with their respective physiological response to fire severity represent a positive feedback loop that reinforce the opposing stand dominance patterns that have developed at the two ends of the fire severity spectrum. Shifts in forest composition from the current dominance by conifers to a future landscape dominated by deciduous forest are of concern due to impacts on climate-albedo feedbacks, forest productivity, ecosystem carbon storage, and wildlife habitat use.

Modeling Fire Severity in Black Spruce Stands in the Alaskan Boreal Forest Using Spectral and Non-Spectral Geospatial Data

NASA Technical Reports Server (NTRS)

Barrett, K.; Kasischke, E. S.; McGuire, A. D.; Turetsky, M. R.; Kane, E. S.

2010-01-01

Biomass burning in the Alaskan interior is already a major disturbance and source of carbon emissions, and is likely to increase in response to the warming and drying predicted for the future climate. In addition to quantifying changes to the spatial and temporal patterns of burned areas, observing variations in severity is the key to studying the impact of changes to the fire regime on carbon cycling, energy budgets, and post-fire succession. Remote sensing indices of fire severity have not consistently been well-correlated with in situ observations of important severity characteristics in Alaskan black spruce stands, including depth of burning of the surface organic layer. The incorporation of ancillary data such as in situ observations and GIS layers with spectral data from Landsat TM/ETM+ greatly improved efforts to map the reduction of the organic layer in burned black spruce stands. Using a regression tree approach, the R2 of the organic layer depth reduction models was 0.60 and 0.55 (pb0.01) for relative and absolute depth reduction, respectively. All of the independent variables used by the regression tree to estimate burn depth can be obtained independently of field observations. Implementation of a gradient boosting algorithm improved the R2 to 0.80 and 0.79 (pb0.01) for absolute and relative organic layer depth reduction, respectively. Independent variables used in the regression tree model of burn depth included topographic position, remote sensing indices related to soil and vegetation characteristics, timing of the fire event, and meteorological data. Post-fire organic layer depth characteristics are determined for a large (N200,000 ha) fire to identify areas that are potentially vulnerable to a shift in post-fire succession. This application showed that 12% of this fire event experienced fire severe enough to support a change in post-fire succession. We conclude that non-parametric models and ancillary data are useful in the modeling of the surface organic layer fire depth. Because quantitative differences in post-fire surface characteristics do not directly influence spectral properties, these modeling techniques provide better information than the use of remote sensing data alone.

Modeling fire severity in black spruce stands in the Alaskan boreal forest using spectral and non-spectral geospatial data

USGS Publications Warehouse

Barrett, Kirsten M.; Kasischke, E.S.; McGuire, A.D.; Turetsky, M.R.; Kane, E.S.

2010-01-01

Biomass burning in the Alaskan interior is already a major disturbance and source of carbon emissions, and is likely to increase in response to the warming and drying predicted for the future climate. In addition to quantifying changes to the spatial and temporal patterns of burned areas, observing variations in severity is the key to studying the impact of changes to the fire regime on carbon cycling, energy budgets, and post-fire succession. Remote sensing indices of fire severity have not consistently been well-correlated with in situ observations of important severity characteristics in Alaskan black spruce stands, including depth of burning of the surface organic layer. The incorporation of ancillary data such as in situ observations and GIS layers with spectral data from Landsat TM/ETM+ greatly improved efforts to map the reduction of the organic layer in burned black spruce stands. Using a regression tree approach, the R2 of the organic layer depth reduction models was 0.60 and 0.55 (pb0.01) for relative and absolute depth reduction, respectively. All of the independent variables used by the regression tree to estimate burn depth can be obtained independently of field observations. Implementation of a gradient boosting algorithm improved the R2 to 0.80 and 0.79 (pb0.01) for absolute and relative organic layer depth reduction, respectively. Independent variables used in the regression tree model of burn depth included topographic position, remote sensing indices related to soil and vegetation characteristics, timing of the fire event, and meteorological data. Post-fire organic layer depth characteristics are determined for a large (N200,000 ha) fire to identify areas that are potentially vulnerable to a shift in post-fire succession. This application showed that 12% of this fire event experienced fire severe enough to support a change in post-fire succession. We conclude that non-parametric models and ancillary data are useful in the modeling of the surface organic layer fire depth. Because quantitative differences in post-fire surface characteristics do not directly influence spectral properties, these modeling techniques provide better information than the use of remote sensing data alone.

Fire and amphibians in North America

USGS Publications Warehouse

Pilliod, D.S.; Bury, R.B.; Hyde, E.J.; Pearl, C.A.; Corn, P.S.

2003-01-01

Information on amphibian responses to fire and fuel reduction practices is critically needed due to potential declines of species and the prevalence of new, more intensive fire management practices in North American forests. The goals of this review are to summarize the known and potential effects of fire and fuels management on amphibians and their aquatic habitats, and to identify information gaps to help direct future scientific research. Amphibians as a group are taxonomically and ecologically diverse; in turn, responses to fire and associated habitat alteration are expected to vary widely among species and among geographic regions. Available data suggest that amphibian responses to fire are spatially and temporally variable and incompletely understood. Much of the limited research has addressed short-term (1–3 years) effects of prescribed fire on terrestrial life stages of amphibians in the southeastern United States. Information on the long-term negative effects of fire on amphibians and the importance of fire for maintaining amphibian communities is sparse for the majority of taxa in North America. Given the size and severity of recent wildland fires and the national effort to reduce fuels on federal lands, future studies are needed to examine the effects of these landscape disturbances on amphibians. We encourage studies to address population-level responses of amphibians to fire by examining how different life stages are affected by changes in aquatic, riparian, and upland habitats. Research designs need to be credible and provide information that is relevant for fire managers and those responsible for assessing the potential effects of various fuel reduction alternatives on rare, sensitive, and endangered amphibian species.

Creation of a retrospective job-exposure matrix using surrogate measures of exposure for a cohort of US career firefighters from San Francisco, Chicago and Philadelphia

PubMed Central

Dahm, Matthew M; Bertke, Stephen; Allee, Steve; Daniels, Robert D

2015-01-01

Objectives To construct a cohort-specific job-exposure matrix (JEM) using surrogate metrics of exposure for a cancer study on career firefighters from the Chicago, Philadelphia and San Francisco Fire Departments. Methods Departmental work history records, along with data on historical annual fire-runs and hours, were collected from 1950 to 2009 and coded into separate databases. These data were used to create a JEM based on standardised job titles and fire apparatus assignments using several surrogate exposure metrics to estimate firefighters’ exposure to the combustion byproducts of fire. The metrics included duration of exposure (cumulative time with a standardised exposed job title and assignment), fire-runs (cumulative events of potential fire exposure) and time at fire (cumulative hours of potential fire exposure). Results The JEM consisted of 2298 unique job titles alongside 16 174 fire apparatus assignments from the three departments, which were collapsed into 15 standardised job titles and 15 standardised job assignments. Correlations were found between fire-runs and time at fires (Pearson coefficient=0.92), duration of exposure and time at fires (Pearson coefficient=0.85), and duration of exposure and fire-runs (Pearson coefficient=0.82). Total misclassification rates were found to be between 16–30% when using duration of employment as an exposure surrogate, which has been traditionally used in most epidemiological studies, compared with using the duration of exposure surrogate metric. Conclusions The constructed JEM successfully differentiated firefighters based on gradient levels of potential exposure to the combustion byproducts of fire using multiple surrogate exposure metrics. PMID:26163543

Creation of a retrospective job-exposure matrix using surrogate measures of exposure for a cohort of US career firefighters from San Francisco, Chicago and Philadelphia.

PubMed

Dahm, Matthew M; Bertke, Stephen; Allee, Steve; Daniels, Robert D

2015-09-01

To construct a cohort-specific job-exposure matrix (JEM) using surrogate metrics of exposure for a cancer study on career firefighters from the Chicago, Philadelphia and San Francisco Fire Departments. Departmental work history records, along with data on historical annual fire-runs and hours, were collected from 1950 to 2009 and coded into separate databases. These data were used to create a JEM based on standardised job titles and fire apparatus assignments using several surrogate exposure metrics to estimate firefighters' exposure to the combustion byproducts of fire. The metrics included duration of exposure (cumulative time with a standardised exposed job title and assignment), fire-runs (cumulative events of potential fire exposure) and time at fire (cumulative hours of potential fire exposure). The JEM consisted of 2298 unique job titles alongside 16,174 fire apparatus assignments from the three departments, which were collapsed into 15 standardised job titles and 15 standardised job assignments. Correlations were found between fire-runs and time at fires (Pearson coefficient=0.92), duration of exposure and time at fires (Pearson coefficient=0.85), and duration of exposure and fire-runs (Pearson coefficient=0.82). Total misclassification rates were found to be between 16-30% when using duration of employment as an exposure surrogate, which has been traditionally used in most epidemiological studies, compared with using the duration of exposure surrogate metric. The constructed JEM successfully differentiated firefighters based on gradient levels of potential exposure to the combustion byproducts of fire using multiple surrogate exposure metrics. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

A NASA-NOAA Update on Global Fire Monitoring Capabilities for Studying Fire-Climate Interactions: Focus on Northern Eurasia

NASA Astrophysics Data System (ADS)

Gutman, G.; Csiszar, I.

2012-04-01

The global, long-term effects of fires are not well understood and we are learning more every year about its global impacts and potential feedbacks to climate change. The frequency, intensity, severity, and emissions of fires may be changing as a result of climate warming as has been manifested by the observations in northern Eurasia. The climate-fire interaction may produce important societal and environmental impacts in the long run. NASA and NOAA have been developing long-term fire datasets and improving systems to monitor active fires, study fire severity, fire growth, emissions into the atmosphere, and fire effects on carbon stocks. Almost every year there are regions in the world that experience particularly severe fires. For example, less than two years ago the European part of Russia was the focus of attention due to the anomalous heat and dry wave with record high temperatures that caused wildfires rage for weeks and that led to thousands of deaths. The fires also have spread to agricultural land and damaged crops, causing sharp increases of global wheat commodity prices. Remote sensing observations are widely used to monitor fire occurrence, fire spread; smoke dispersion, and atmospheric pollutant levels. In the context of climate warming and acute interest to large-scale emissions from various land-cover disturbances studying spatial-temporal dynamics of forest fire activity is critical. NASA supports several activities related to fires and the Earth system. These include GOFC-GOLD Fire Project Office at University of Maryland and the Rapid Response System for global fire monitoring. NASA has funded many research projects on biomass burning, which cover various geographic regions of the world and analyze impacts of fires on atmospheric carbon in support of REDD initiative, as well as on atmospheric pollution with smoke. Monitoring active fires, studying their severity and burned areas, and estimating fire-induced atmospheric emissions has been the subject of several research projects in the NASA LCLUC program over the globe, and, in particular, in Northern Eurasia. As an operational agency, NOAA puts global fire monitoring as a priority and supports related GCOS, CEOS and GOFC-GOLD objectives. NOAA developed an operational quasi-global fire monitoring system using geostationary satellites that provides coverage over parts of Northern Eurasia. Fire products from the VIIRS (Visible Infrared Imager Radiometer Suite) sensor on the NPP (NPOESS Preparatory Project) satellite, launched in October 2011, and on subsequent JPSS satellites will ensure high quality global fire monitoring and will extent the AVHRR- and MODIS-based fire data record over Northern Eurasia. This overview presents an update of NASA's and NOAA's fire monitoring capability and scientific achievements on fire-climate interactions. We will illustrate how combination of coarse spatial resolution polar orbiting satellite observations are combined with moderate spatial resolution observations to better monitor the location of fires and burned areas. While coarse resolution data have been more or less easily available, the utility of moderate resolution Landsat data has increased tremendously during the past couple of years once the data became freely available. Data fusion from polar orbiting and geostationary satellites will be discussed.

Using synthetic polymers to reduce soil erosion after forest fires in Mediterranean soils

NASA Astrophysics Data System (ADS)

Lado, Marcos; Ben-Hur, Meni; Inbar, Assaf

2010-05-01

Forest fires are a major environmental problem in the Mediterranean region because they result in a loss of vegetation cover, changes in biodiversity, increases in greenhouse gasses emission and a potential increase of runoff and soil erosion. The large increases in runoff and sediment yields after high severity fires have been attributed to several factors, among them: increase in soil water repellency; soil sealing by detached particles and by ash particles, and the loss of a surface cover. The presence of a surface cover increases infiltration, and decreases runoff and erosion by several mechanisms which include: rainfall interception, plant evapotranspiration, preservation of soil structure by increasing soil organic matter, and increasing surface roughness. The loss of vegetation cover as a result of fire leaves the surface of the soil exposed to the direct impact of the raindrops, and therefore the sensitivity of the soil to runoff generation and soil loss increases. In this work, we propose a new method to protect soils against post-fire erosion based on the application of synthetic polymers to the soil. Laboratory rainfall simulations and field runoff plots were used to analyze the suitability of the application of synthetic polymers to reduce soil erosion and stabilize soil structure in Mediterranean soils. The combination of these two processes will potentially favor a faster recovery of the vegetation structure. This method has been successfully applied in arable land, however it has not been tested in burnt forests. The outcome of this study may provide important managerial tools for forest management following fires.

Climate drives inter-annual variability in probability of high severity fire occurrence in the western United States

NASA Astrophysics Data System (ADS)

Keyser, Alisa; Westerling, Anthony LeRoy

2017-05-01

A long history of fire suppression in the western United States has significantly changed forest structure and ecological function, leading to increasingly uncharacteristic fires in terms of size and severity. Prior analyses of fire severity in California forests showed that time since last fire and fire weather conditions predicted fire severity very well, while a larger regional analysis showed that topography and climate were important predictors of high severity fire. There has not yet been a large-scale study that incorporates topography, vegetation and fire-year climate to determine regional scale high severity fire occurrence. We developed models to predict the probability of high severity fire occurrence for the western US. We predict high severity fire occurrence with some accuracy, and identify the relative importance of predictor classes in determining the probability of high severity fire. The inclusion of both vegetation and fire-year climate predictors was critical for model skill in identifying fires with high fractional fire severity. The inclusion of fire-year climate variables allows this model to forecast inter-annual variability in areas at future risk of high severity fire, beyond what slower-changing fuel conditions alone can accomplish. This allows for more targeted land management, including resource allocation for fuels reduction treatments to decrease the risk of high severity fire.

Political and technical issues of coal fire extinction in the Kyoto framework

NASA Astrophysics Data System (ADS)

Meyer, U.; Chen-Brauchler, D.; Rüter, H.; Fischer, C.; Bing, K.

2009-04-01

It is a highly desirable effort to extinguish as much coal fires as possible in short time to prevent large losses of energy resources and to minimise CO2 and other exhaust gas releases from such sources. Unfortunately, extinguishing coal fires needs massive financial investments, skilled man power, suited technology and a long time. Even mid to small scale coal fires need several months of extinguishing measures and of monitoring time after extinction resulting in expenditures of a minimum of several hundred thousand Euros. Large companies might be willing to spend money for coal fire extinction measures but smaller holdings or regional governments might not have the monetary resources for it. Since there is no law in China that demands coal fire extinction, measures under the Kyoto framework may be applied to sell CO2 certificates for prevented emissions from extinguished coal fires and thus used as a financial stimulus for coal fire extinction activities. The set-up for methodologies and project designs is especially complex for coal fire extinction measures and thus for necessary exploration, evaluation and monitoring using geophysical and remote sensing methods. A brief overview of most important formal and technical aspects is given to outline the conditions for a potentially successful CDM application on coal fires based on geophysical observations and numerical modelling.

Twenty Years After the 1988 Yellowstone Fires: Lessons About Disturbance and Ecosystems

USGS Publications Warehouse

Romme, W.H.; Boyce, M.S.; Gresswell, R.; Merrill, E.H.; Minshall, G.W.; Whitlock, C.; Turner, M.G.

2011-01-01

The 1988 Yellowstone fires were among the first in what has proven to be an upsurge in large severe fires in the western USA during the past 20 years. At the time of the fires, little was known about the impacts of such a large severe disturbance because scientists had had few previous opportunities to study such an event. Ecologists predicted short- and long-term effects of the 1988 fires on vegetation, biogeochemistry, primary productivity, wildlife, and aquatic ecosystems based on scientific understanding of the time. Twenty-plus years of subsequent study allow these early predictions to be evaluated. Most of the original predictions were at least partially supported, but some predictions were refuted, others nuanced, and a few postfire phenomena were entirely unexpected. Post-1988 Yellowstone studies catalyzed advances in ecology focused on the importance of spatial and temporal heterogeneity, contingent influences, and multiple interacting drivers. Post-1988 research in Yellowstone also has changed public perceptions of fire as an ecological process and attitudes towards fire management. Looking ahead to projected climate change and more frequent large fires, the well-documented ecological responses to the 1988 Yellowstone fires provide a foundation for detecting and evaluating potential changes in fire regimes of temperate mountainous regions. ?? 2011 Springer Science+Business Media, LLC.

Impact of fire on active layer and permafrost microbial communities and metagenomes in an upland Alaskan boreal forest.

PubMed

Taş, Neslihan; Prestat, Emmanuel; McFarland, Jack W; Wickland, Kimberley P; Knight, Rob; Berhe, Asmeret Asefaw; Jorgenson, Torre; Waldrop, Mark P; Jansson, Janet K

2014-09-01

Permafrost soils are large reservoirs of potentially labile carbon (C). Understanding the dynamics of C release from these soils requires us to account for the impact of wildfires, which are increasing in frequency as the climate changes. Boreal wildfires contribute to global emission of greenhouse gases (GHG-CO2, CH4 and N2O) and indirectly result in the thawing of near-surface permafrost. In this study, we aimed to define the impact of fire on soil microbial communities and metabolic potential for GHG fluxes in samples collected up to 1 m depth from an upland black spruce forest near Nome Creek, Alaska. We measured geochemistry, GHG fluxes, potential soil enzyme activities and microbial community structure via 16SrRNA gene and metagenome sequencing. We found that soil moisture, C content and the potential for respiration were reduced by fire, as were microbial community diversity and metabolic potential. There were shifts in dominance of several microbial community members, including a higher abundance of candidate phylum AD3 after fire. The metagenome data showed that fire had a pervasive impact on genes involved in carbohydrate metabolism, methanogenesis and the nitrogen cycle. Although fire resulted in an immediate release of CO2 from surface soils, our results suggest that the potential for emission of GHG was ultimately reduced at all soil depths over the longer term. Because of the size of the permafrost C reservoir, these results are crucial for understanding whether fire produces a positive or negative feedback loop contributing to the global C cycle.

Impact of fire on active layer and permafrost microbial communities and metagenomes in an upland Alaskan boreal forest

PubMed Central

Taş, Neslihan; Prestat, Emmanuel; McFarland, Jack W; Wickland, Kimberley P; Knight, Rob; Berhe, Asmeret Asefaw; Jorgenson, Torre; Waldrop, Mark P; Jansson, Janet K

2014-01-01

Permafrost soils are large reservoirs of potentially labile carbon (C). Understanding the dynamics of C release from these soils requires us to account for the impact of wildfires, which are increasing in frequency as the climate changes. Boreal wildfires contribute to global emission of greenhouse gases (GHG—CO2, CH4 and N2O) and indirectly result in the thawing of near-surface permafrost. In this study, we aimed to define the impact of fire on soil microbial communities and metabolic potential for GHG fluxes in samples collected up to 1 m depth from an upland black spruce forest near Nome Creek, Alaska. We measured geochemistry, GHG fluxes, potential soil enzyme activities and microbial community structure via 16SrRNA gene and metagenome sequencing. We found that soil moisture, C content and the potential for respiration were reduced by fire, as were microbial community diversity and metabolic potential. There were shifts in dominance of several microbial community members, including a higher abundance of candidate phylum AD3 after fire. The metagenome data showed that fire had a pervasive impact on genes involved in carbohydrate metabolism, methanogenesis and the nitrogen cycle. Although fire resulted in an immediate release of CO2 from surface soils, our results suggest that the potential for emission of GHG was ultimately reduced at all soil depths over the longer term. Because of the size of the permafrost C reservoir, these results are crucial for understanding whether fire produces a positive or negative feedback loop contributing to the global C cycle. PMID:24722629

Evidence of fuels management and fire weather influencing fire severity in an extreme fire event

USGS Publications Warehouse

Lydersen, Jamie M; Collins, Brandon M.; Brooks, Matthew L.; Matchett, John R.; Shive, Kristen L.; Povak, Nicholas A.; Kane, Van R.; Smith, Douglas F.

2017-01-01

Following changes in vegetation structure and pattern, along with a changing climate, large wildfire incidence has increased in forests throughout the western U.S. Given this increase there is great interest in whether fuels treatments and previous wildfire can alter fire severity patterns in large wildfires. We assessed the relative influence of previous fuels treatments (including wildfire), fire weather, vegetation and water balance on fire severity in the Rim Fire of 2013. We did this at three different spatial scales to investigate whether the influences on fire severity changed across scales. Both fuels treatments and previous low to moderate severity wildfire reduced the prevalence of high severity fire. In general, areas without recent fuels treatments and areas that previously burned at high severity tended to have a greater proportion of high severity fire in the Rim Fire. Areas treated with prescribed fire, especially when combined with thinning, had the lowest proportions of high severity. Proportion of the landscape burned at high severity was most strongly influenced by fire weather and proportional area previously treated for fuels or burned by low to moderate severity wildfire. The proportion treated needed to effectively reduce the amount of high fire severity fire varied by spatial scale of analysis, with smaller spatial scales requiring a greater proportion treated to see an effect on fire severity. When moderate and high severity fire encountered a previously treated area, fire severity was significantly reduced in the treated area relative to the adjacent untreated area. Our results show that fuels treatments and low to moderate severity wildfire can reduce fire severity in a subsequent wildfire, even when burning under fire growth conditions. These results serve as further evidence that both fuels treatments and lower severity wildfire can increase forest resilience.

Postfire soil burn severity mapping with hyperspectral image unmixing

USGS Publications Warehouse

Robichaud, P.R.; Lewis, S.A.; Laes, D.Y.M.; Hudak, A.T.; Kokaly, R.F.; Zamudio, J.A.

2007-01-01

Burn severity is mapped after wildfires to evaluate immediate and long-term fire effects on the landscape. Remotely sensed hyperspectral imagery has the potential to provide important information about fine-scale ground cover components that are indicative of burn severity after large wildland fires. Airborne hyperspectral imagery and ground data were collected after the 2002 Hayman Fire in Colorado to assess the application of high resolution imagery for burn severity mapping and to compare it to standard burn severity mapping methods. Mixture Tuned Matched Filtering (MTMF), a partial spectral unmixing algorithm, was used to identify the spectral abundance of ash, soil, and scorched and green vegetation in the burned area. The overall performance of the MTMF for predicting the ground cover components was satisfactory (r2 = 0.21 to 0.48) based on a comparison to fractional ash, soil, and vegetation cover measured on ground validation plots. The relationship between Landsat-derived differenced Normalized Burn Ratio (dNBR) values and the ground data was also evaluated (r2 = 0.20 to 0.58) and found to be comparable to the MTMF. However, the quantitative information provided by the fine-scale hyperspectral imagery makes it possible to more accurately assess the effects of the fire on the soil surface by identifying discrete ground cover characteristics. These surface effects, especially soil and ash cover and the lack of any remaining vegetative cover, directly relate to potential postfire watershed response processes. ?? 2006 Elsevier Inc. All rights reserved.

The potential for pulmonary heat injury resulting from the activation of a cabin water spray system to fight aircraft cabin fires.

DOT National Transportation Integrated Search

1995-05-01

A cabin water spray system (CWSS) has been suggested as a means of attenuating the severity of smoke and fire commonly associated with aircraft accidents. All aspects of passenger and cabin safety must be considered when evaluating a new safety syste...

Differential impacts of wildfire on the population dynamics of an old-forest species.

PubMed

Rockweit, Jeremy T; Franklin, Alan B; Carlson, Peter C

2017-06-01

Ecological disturbances shape and maintain natural communities, but climate change and human land use can alter disturbance regimes and affect population persistence and vital rates in unpredictable ways. Species inhabiting landscapes shaped by wildfire have evolved mechanisms allowing them to persist under this dynamic disturbance type, which creates habitats of varying quality for these species. We utilized data from a 26-yr demographic study of northern spotted owls to analyze the influence of wildfire on apparent survival and recruitment rates. Wildfires occurred across different years and affected different spotted owl territories, which allowed us to implement a retrospective Before-After-Control-Impact (BACI) analysis and model the potential effect of wildfire extent and severity. Our results indicated that mixed-severity fires that burned at predominantly low-severity had little effect on survival and recruitment while fires characterized by more medium to high burn severities negatively affected spotted owl survival, with varying effects on recruitment. Reduced survival and increased recruitment rates on some territories affected by medium to high severity fires suggested that post-fire habitat quality was reduced resulting in territories that were marginally capable of supporting owls. We hypothesize these territories may have represented "sinks" that were supported by nearby "source" territories in a spatially heterogeneous landscape created by the mixed-severity fire regime of the region. © 2017 by the Ecological Society of America.

A multi-scale conceptual model of fire and disease interactions in North American forests

NASA Astrophysics Data System (ADS)

Varner, J. M.; Kreye, J. K.; Sherriff, R.; Metz, M.

2013-12-01

One aspect of global change with increasing attention is the interactions between irruptive pests and diseases and wildland fire behavior and effects. These pests and diseases affect fire behavior and effects in spatially and temporally complex ways. Models of fire and pathogen interactions have been constructed for individual pests or diseases, but to date, no synthesis of this complexity has been attempted. Here we synthesize North American fire-pathogen interactions into syndromes with similarities in spatial extent and temporal duration. We base our models on fire interactions with three examples: sudden oak death (caused by the pathogen Phytopthora ramorum) and the native tree tanoak (Notholithocarpus densiflorus); mountain pine beetle (Dendroctonus ponderosae) and western Pinus spp.; and hemlock woolly adelgid (Adelges tsugae) on Tsuga spp. We evaluate each across spatial (severity of attack from branch to landscape scale) and temporal scales (from attack to decades after) and link each change to its coincident effects on fuels and potential fire behavior. These syndromes differ in their spatial and temporal severity, differentially affecting windows of increased or decreased community flammability. We evaluate these models with two examples: the recently emergent ambrosia beetle-vectored laurel wilt (caused by the pathogen Raffaelea lauricola) in native members of the Lauraceae and the early 20th century chestnut blight (caused by the pathogen Cryphonectria parasitica) that led to the decline of American chestnut (Castanea dentata). Some changes (e.g., reduced foliar moisture content) have short-term consequences for potential fire behavior while others (functional extirpation) have more complex indirect effects on community flammability. As non-native emergent diseases and pests continue, synthetic models that aid in prediction of fire behavior and effects will enable the research and management community to prioritize mitigation efforts to realized effects.

Evaluation of a boron-nitrogen, phosphate-free fire-retardant treatment. Part II, Testing of small clear specimens per ASTM Standard D 5664-95, Methods A and B

Treesearch

Jerrold E. Winandy; Douglas Herdman

2003-01-01

The objective of this work was to evaluate the effects of a new boron-nitrogen, phosphate-free fire-retardant (FR) formulation on several mechanical properties of FR-treated wood and to assess the potential of this treatment for in-service thermal-induced strength loss resulting from exposure to high temperature. Fire-retardant-treated and untreated small clear...

Spatial patterns of large natural fires in Sierra Nevada wilderness areas

USGS Publications Warehouse

Collins, B.M.; Kelly, M.; van Wagtendonk, J.W.; Stephens, S.L.

2007-01-01

The effects of fire on vegetation vary based on the properties and amount of existing biomass (or fuel) in a forest stand, weather conditions, and topography. Identifying controls over the spatial patterning of fire-induced vegetation change, or fire severity, is critical in understanding fire as a landscape scale process. We use gridded estimates of fire severity, derived from Landsat ETM+ imagery, to identify the biotic and abiotic factors contributing to the observed spatial patterns of fire severity in two large natural fires. Regression tree analysis indicates the importance of weather, topography, and vegetation variables in explaining fire severity patterns between the two fires. Relative humidity explained the highest proportion of total sum of squares throughout the Hoover fire (Yosemite National Park, 2001). The lowest fire severity corresponded with increased relative humidity. For the Williams fire (Sequoia/Kings Canyon National Parks, 2003) dominant vegetation type explains the highest proportion of sum of squares. Dominant vegetation was also important in determining fire severity throughout the Hoover fire. In both fires, forest stands that were dominated by lodgepole pine (Pinus contorta) burned at highest severity, while red fir (Abies magnifica) stands corresponded with the lowest fire severities. There was evidence in both fires that lower wind speed corresponded with higher fire severity, although the highest fire severity in the Williams fire occurred during increased wind speed. Additionally, in the vegetation types that were associated with lower severity, burn severity was lowest when the time since last fire was fewer than 11 and 17 years for the Williams and Hoover fires, respectively. Based on the factors and patterns identified, managers can anticipate the effects of management ignited and naturally ignited fires at the forest stand and the landscape levels. ?? 2007 Springer Science+Business Media, Inc.

Experimental Studies on the Flammability and Fire Hazards of Photovoltaic Modules

PubMed Central

Yang, Hong-Yun; Zhou, Xiao-Dong; Yang, Li-Zhong; Zhang, Tao-Lin

2015-01-01

Many of the photovoltaic (PV) systems on buildings are of sufficiently high voltages, with potential to cause or promote fires. However, research about photovoltaic fires is insufficient. This paper focuses on the flammability and fire hazards of photovoltaic modules. Bench-scale experiments based on polycrystalline silicon PV modules have been conducted using a cone calorimeter. Several parameters including ignition time (tig), mass loss, heat release rate (HRR), carbon monoxide (CO) and carbon dioxide (CO2) concentration, were investigated. The fire behaviours, fire hazards and toxicity of gases released by PV modules are assessed based on experimental results. The results show that PV modules under tests are inflammable with the critical heat flux of 26 kW/m2. This work will lead to better understanding on photovoltaic fires and how to help authorities determine the appropriate fire safety provisions for controlling photovoltaic fires. PMID:28793434

Experimental Studies on the Flammability and Fire Hazards of Photovoltaic Modules.

PubMed

Yang, Hong-Yun; Zhou, Xiao-Dong; Yang, Li-Zhong; Zhang, Tao-Lin

2015-07-09

Many of the photovoltaic (PV) systems on buildings are of sufficiently high voltages, with potential to cause or promote fires. However, research about photovoltaic fires is insufficient. This paper focuses on the flammability and fire hazards of photovoltaic modules. Bench-scale experiments based on polycrystalline silicon PV modules have been conducted using a cone calorimeter. Several parameters including ignition time ( t ig ), mass loss, heat release rate (HRR), carbon monoxide (CO) and carbon dioxide (CO₂) concentration, were investigated. The fire behaviours, fire hazards and toxicity of gases released by PV modules are assessed based on experimental results. The results show that PV modules under tests are inflammable with the critical heat flux of 26 kW/m². This work will lead to better understanding on photovoltaic fires and how to help authorities determine the appropriate fire safety provisions for controlling photovoltaic fires.

Changes in Fire-Derived Soil Black Carbon Storage in a Sub-humid Woodland

NASA Astrophysics Data System (ADS)

White, J. D.; Yao, J.; Murray, D. B.; Hockaday, W. C.

2014-12-01

Fire-derived black carbon (BC) in soil, including charcoal, represents a potentially important fraction of terrestrial carbon cycling due to its presumed long persistence in soil. Interpretation of site BC retention is important for assessing feedbacks to ecosystem processes including nutrient and water cycling. However, interaction between vegetation disturbance, BC formation, and off site transport may exist that complicate interpretation of BC addition to soils from wildfire or prescribed burns directly. To investigate the relationship between disturbance and site retention on soil BC, we determined BC concentrations for a woodland in central Texas, USA, from study plots in hilly terrain with a fire scar dendrochronology spanning 100 years. BC values were determined from 13C nuclear magnetic resonance (NMR) spectroscopy. Estimated values showed mean BC concentration of 2.73 ± 3.06 g BC kg-1 (0.91 ± 0.51 kg BC m-2) for sites with fire occurrence within the last 40 years compared with BC values of1.21 ± 1.70 g BC kg-1 soil (0.18 ± 0.14 kg BC m-2) for sites with fire 40 - 100 years ago. Sites with no tree ring evidence of fire during the last 100 years had the lowest mean soil BC concentration of 0.05 ± 0.11 g BC kg-1 (0.02 ± 0.03 kg BC m-2). Molecular proxies of stability (lignin/N) and decomposition (Alkyl C/O-Alky C) showed no differences across the sites, indicating that low potential for BC mineralization. Modeled soil erosion and time since fire from fire scar data showed that soil BC concentrations were inversely correlated. A modified the ecosystem process model, Biome-BGC, was also used simulate the effects of fire disturbance with different severities and seasonality on C cycling related to the BC production, effect on soil water availability, and off-site transport. Results showed that BC impacts on ecosystem processes, including net ecosystem exchange and leaf area development, were predominantly related to fire frequency. Site BC loss rates were affected by initial slope-affected erosion, fire severity, vegetation type, and rate of vegetation recovery. The simulation results showed that fire types, such as high severity, was generally associated with low site BC retention related to low vertical transfer of BC into soils, buoyancy of BC particles, and surface runoff from unvegetated soils.

Prioritizing forest fuels treatments based on the probability of high-severity fire restores adaptive capacity in Sierran forests.

PubMed

Krofcheck, Daniel J; Hurteau, Matthew D; Scheller, Robert M; Loudermilk, E Louise

2018-02-01

In frequent fire forests of the western United States, a legacy of fire suppression coupled with increases in fire weather severity have altered fire regimes and vegetation dynamics. When coupled with projected climate change, these conditions have the potential to lead to vegetation type change and altered carbon (C) dynamics. In the Sierra Nevada, fuels reduction approaches that include mechanical thinning followed by regular prescribed fire are one approach to restore the ability of the ecosystem to tolerate episodic fire and still sequester C. Yet, the spatial extent of the area requiring treatment makes widespread treatment implementation unlikely. We sought to determine if a priori knowledge of where uncharacteristic wildfire is most probable could be used to optimize the placement of fuels treatments in a Sierra Nevada watershed. We developed two treatment placement strategies: the naive strategy, based on treating all operationally available area and the optimized strategy, which only treated areas where crown-killing fires were most probable. We ran forecast simulations using projected climate data through 2,100 to determine how the treatments differed in terms of C sequestration, fire severity, and C emissions relative to a no-management scenario. We found that in both the short (20 years) and long (100 years) term, both management scenarios increased C stability, reduced burn severity, and consequently emitted less C as a result of wildfires than no-management. Across all metrics, both scenarios performed the same, but the optimized treatment required significantly less C removal (naive=0.42 Tg C, optimized=0.25 Tg C) to achieve the same treatment efficacy. Given the extent of western forests in need of fire restoration, efficiently allocating treatments is a critical task if we are going to restore adaptive capacity in frequent-fire forests. © 2017 John Wiley & Sons Ltd.

Wildland fire and climate variability impacts on annual streamflow in watersheds across the continental United States: Regional patterns and attribution analysis

NASA Astrophysics Data System (ADS)

Hallema, D. W.; Sun, G.; Caldwell, P. V.; Norman, S. P.; Cohen, E. C.; Liu, Y.; McNulty, S. G.

2016-12-01

The magnitude of wildland fire impacts on water resources varies regionally depending on fire severity, topography, vegetation and climate. An assessment of the potential threat that wildland fire poses to water supplies across the conterminous United States (CONUS) is critically important because forests supply 50% of consumed water. In our assessment, we first performed a double mass analysis of streamflow (GAGES-II) vs. precipitation (PRISM) data from 170 burned watersheds to identify changes in average water yield in the first five years following wildland fire (MTBS burn severity dataset), which were positive in 52 watersheds (Chow test p<0.1), negative in 69 (p<0.1), and not significant in 49 (p>0.1). Subsequently, we separated the respective contributions of fire and climate variability to changes in annual runoff (dQ) by fitting linear climate elasticity models (CEMs), yielding acceptable CEMs (coefficient p<0.1) for 106 watersheds. Median dQ (MdQ) for 62 watersheds with a burned area to drainage area ratio (BAR) <10% declined by -12%, mostly attributed to lower annual precipitation (P) (-16%) associated with regional climate trends, which was a common response in watersheds in the eastern states with low severity prescribed (Rx) or wildfires. MdQ increased by +11% in 44 watersheds with BAR >10%, notwithstanding overall declining P. These watersheds were for the greatest part located in the western CONUS, where dQ was correlated with burn severity (R2>0.53, variable per severity class) and PET (R2=0.73). The most severe impacts were observed in Arizona (2005 Cave Creek Complex, 2004 Edge Complex and 2004 Willow Fires), with BARs >39% and dQ>+160%, while hydrologic response in the east was much less extreme with only 10 cases where post-fire dQ increased >+10%. The clear regional patterns in post-fire Q together with evidence showing that downward trends in P can mask flow enhancing effects of fire disturbance (24 watersheds), underline the importance of the combined analysis of wildland fire and climate impacts in national scale assessments. Research funded by the USDA Forest Service Southern Research Station, Joint Fire Science Program (#14-1-06-18), and Oak Ridge Institute for Science and Education (U.S. Department of Energy).

Wildfire in the Critical Zone: Pyro-Geomorphic Feedbacks in Upland Forests

NASA Astrophysics Data System (ADS)

Sheridan, G. J.; Inbar, A.; Metzen, D.; Van der Sant, R.; Lane, P. N. J.; Nyman, P.

2017-12-01

Wildfire often triggers a dramatic geomorphic response, with erosion rates several orders of magnitude greater than background rates. The fact that wildfire is linked to increased soil erosion is well established, but could it also work the other way around? Is it possible that, over time, soil erosion could lead to an increase in wildfire? The proposed mechanism for this is a potential positive feedback between post-fire soil erosion, soil depth, and forest flammability. More fire-related erosion may, over time, lead to less soil water holding capacity, more open vegetation with drier fuels, more fire, and in turn more fire related erosion. These pyro-geomorphic feedbacks may help explain the co-evolved soil-vegetation-fire systems that are observed in the landscape. More broadly, the concept of "wildfire in the critical zone", with a greater emphasis on the interactions between fire, vegetation, hydrology, and geomorphology, may help us understand and predict the trajectory of change as the vegetation-soil-fire system responds and adjusts to the new climate forcing. This presentation will combine an extensive soil, vegetation, and post fire erosion experimental dataset, with conceptual and numerical modelling, to evaluate the significance of the potential pyro-geomorphic feedbacks described above.

Wildfire Emissions and Their Interaction with Urban and Rural Pollution: Data and Simulations

NASA Technical Reports Server (NTRS)

Singh, H. B.

2014-01-01

In recent years NASA has conducted a series of airborne campaigns (e. g. SEAC4RS*, ARCTAS, INTEX-A/B) over North America using an instrumented DC-8 aircraft equipped to measure a very large number of gaseous and aerosol constituents including several unique tracers. In these campaigns wild fires were extensively sampled near source as well as downwind after aging. The data provided detailed information on the composition and chemistry of fire emissions under a variety of atmospheric conditions as well as their interactions with rural and urban air pollution. Major fires studied including the California Rim fire in 2013 (SEAC4RS), the 2008 California wildfires (ARCTAS), and the Alaskan fires downwind over eastern US (INTEX-A). Although some fire plumes contained virtually no O3 enhancement, others showed significant ozone formation. Over Los Angeles, the highest O3 mixing ratios were observed in fire influenced urban air masses. Attempts to simulate these interactions using state of the art models were only minimally successful and indicated several shortcomings in simulating fire emission influences on urban smog formation. A variety of secondary oxidation products (e. g. O3, PAN, HCHO) were substantially underestimated. We will discuss the data collected in fire influenced air masses and their potential air quality implications.

Targeting Forest Management through Fire and Erosion Modeling

NASA Astrophysics Data System (ADS)

Elliot, William J.; Miller, Mary Ellen; MacDonald, Lee H.

2013-04-01

Forests deliver a number of ecosystem services, including clean water. When forests are disturbed by wildfire, the timing and quantity of runoff can be altered, and the quality can be severely degraded. A modeling study for about 1500 km2 in the Upper Mokelumne River Watershed in California was conducted to determine the risk of wildfire and the associated potential sediment delivery should a wildfire occur, and to calculate the potential reduction in sediment delivery that might result from fuel reduction treatments. The first step was to predict wildfire severity and probability of occurrence under current vegetation conditions with FlamMap fire prediction tool. FlamMap uses current vegetation, topography, and wind characteristics to predict the speed, flame length, and direction of a simulated flame front for each 30-m pixel. As the first step in the erosion modeling, a geospatial interface for the WEPP model (GeoWEPP) was used to delineate approximately 6-ha hillslope polygons for the study area. The flame length values from FlamMap were then aggregated for each hillslope polygon to yield a predicted fire intensity. Fire intensity and pre-fire vegetation conditions were used to estimate fire severity (either unburned, low, moderate or high). The fire severity was combined with soil properties from the STATSGO database to build the vegetation and soil files needed to run WEPP for each polygon. Eight different stochastic climates were generated to account for the weather variability within the basin. A modified batching version of GeoWEPP was used to predict the first-year post-fire sediment yield from each hillslope and subwatershed. Estimated sediment yields ranged from 0 to more than 100 Mg/ha, and were typical of observed values. The polygons that generated the greatest amount of sediment or that were critical for reducing fire spread were identified, and these were "treated" by reducing the amount of fuel available for a wildfire. The erosion associated with these fuel treatments was estimated using WEPP. FlamMap and WEPP were run a second time to determine the extent to which the imposed treatments reduced fire intensity, fire severity, and the predicted sediment yields. The results allowed managers to quantify the net reduction in sediment delivery due to the prescribed treatments. The modeling also identified those polygons with the greatest net decline in sediment delivery, with the expectation that these polygons would have the highest priority for fuel reduction treatments. An economic value can be assigned to the predicted net change in sediment delivered to a reservoir or a specified decline in water quality. The estimated avoided costs due to the reduction in sediment delivery can help justify the optimized fuel treatments.

Measuring moisture dynamics to predict fire severity in longleaf pine forests.

Treesearch

Sue A. Ferguson; Julia E. Ruthford; Steven J. McKay; David Wright; Clint Wright; Roger Ottmar

2002-01-01

To understand the combustion limit of biomass fuels in a longleaf pine (Pinus palustris) forest, an experiment was conducted to monitor the moisture content of potentially flammable forest floor materials (litter and duff) at Eglin Air Force Base in the Florida Panhandle. While longleaf pine forests are fire dependent ecosystems, a long history of...

Relating fuel loads to overstorey structure and composition in a fire-excluded Sierra Nevada mixed conifer forest

Treesearch

Jamie M. Lydersen; Brandon M. Collins; Eric E. Knapp; Gary B. Roller; Scott Stephens

2015-01-01

Although knowledge of surface fuel loads is critical for evaluating potential fire behaviour and effects, their inherent variability makes these difficult to quantify. Several studies relate fuel loads to vegetation type, topography and spectral imaging, but little work has been done examining relationships between forest overstorey variables and surface fuel...

Earth, wind, and fire: Wildfire risk perceptions in a hurricane-prone environment

Treesearch

Soren M. Newman; Matthew S. Carroll; Pamela J. Jakes; Daniel R. Williams; Lorie L. Higgins

2014-01-01

Wildfire is one of several potential disturbances that could have extraordinary impacts on individuals and communities in fire-prone areas. In this article we describe disturbance risk perceptions from interviews with residents in three Florida communities that face significant wildfire and hurricane risk. Although they live in areas characterized by emergency managers...

Modeling post-fire hydro-geomorphic recovery in the Waldo Canyon Fire

NASA Astrophysics Data System (ADS)

Kinoshita, Alicia; Nourbakhshbeidokhti, Samira; Chin, Anne

2016-04-01

Wildfire can have significant impacts on watershed hydrology and geomorphology by changing soil properties and removing vegetation, often increasing runoff and soil erosion and deposition, debris flows, and flooding. Watershed systems may take several years or longer to recover. During this time, post-fire channel changes have the potential to alter hydraulics that influence characteristics such as time of concentration and increase time to peak flow, flow capacity, and velocity. Using the case of the 2012 Waldo Canyon Fire in Colorado (USA), this research will leverage field-based surveys and terrestrial Light Detection and Ranging (LiDAR) data to parameterize KINEROS2 (KINematic runoff and EROSion), an event oriented, physically-based watershed runoff and erosion model. We will use the Automated Geospatial Watershed Assessment (AGWA) tool, which is a GIS-based hydrologic modeling tool that uses commonly available GIS data layers to parameterize, execute, and spatially visualize runoff and sediment yield for watersheds impacted by the Waldo Canyon Fire. Specifically, two models are developed, an unburned (Bear Creek) and burned (Williams) watershed. The models will simulate burn severity and treatment conditions. Field data will be used to validate the burned watersheds for pre- and post-fire changes in infiltration, runoff, peak flow, sediment yield, and sediment discharge. Spatial modeling will provide insight into post-fire patterns for varying treatment, burn severity, and climate scenarios. Results will also provide post-fire managers with improved hydro-geomorphic modeling and prediction tools for water resources management and mitigation efforts.

Strengthening community participation in reducing GHG emission from forest and peatland fire

NASA Astrophysics Data System (ADS)

Thoha, A. S.; Saharjo, B. H.; Boer, R.; Ardiansyah, M.

2018-02-01

Strengthening community participation is needed to find solutions to encourage community more participate in reducing Green House Gas (GHG) from forest and peatland fire. This research aimed to identify stakeholders that have the role in forest and peatland fire control and to formulate strengthening model of community participation through community-based early warning fire. Stakeholder mapping and action research were used to determine stakeholders that had potential influence and interest and to formulate strengthening model of community participation in reducing GHG from forest and peatland fire. There was found that position of key players in the mapping of stakeholders came from the government institution. The existence of community-based fire control group can strengthen government institution through collaborating with stakeholders having strong interest and influence. Moreover, it was found several local knowledge in Kapuas District about how communities predict drought that have potential value for developing the community-based early warning fire system. Formulated institutional model in this research also can be further developed as a model institution in the preservation of natural resources based on local knowledge. In conclusion, local knowledge and community-based fire groups can be integrated within strengthening model of community participation in reducing GHG from forest and peatland fire.

Assessment of Fire Occurrence and Future Fire Potential in Arctic Alaska

NASA Astrophysics Data System (ADS)

French, N. H. F.; Jenkins, L. K.; Loboda, T. V.; Bourgeau-Chavez, L. L.; Whitley, M. A.

2014-12-01

An analysis of the occurrence of fire in Alaskan tundra was completed using the relatively complete historical record of fire for the region from 1950 to 2013. Spatial fire data for Alaskan tundra regions were obtained from the Alaska Large Fire Database for the region defined from vegetation and ecoregion maps. A detailed presentation of fire records available for assessing the fire regime of the tundra regions of Alaska as well as results evaluating fire size, seasonality, and general geographic and temporal trends is included. Assessment of future fire potential was determined for three future climate scenarios at four locations across the Alaskan tundra using the Canadian Forest Fire Weather Index (FWI). Canadian Earth System Model (CanESM2) weather variables were used for historical (1850-2005) and future (2006-2100) time periods. The database includes 908 fire points and 463 fire polygons within the 482,931 km2 of Alaskan tundra. Based on the polygon database 25,656 km2 (6,340,000 acres) has burned across the six tundra ecoregions since 1950. Approximately 87% of tundra fires start in June and July across all ecoregions. Combining information from the polygon and points data records, the estimated average fire size for fire in the Alaskan Arctic region is 28.1 km2 (7,070 acres), which is much smaller than in the adjacent boreal forest region, averaging 203 km2 for high fire years. The largest fire in the database is the Imuruk Basin Fire which burned 1,680 km2 in 1954 in the Seward Peninsula region (Table 1). Assessment of future fire potential shows that, in comparison with the historical fire record, fire occurrence in Alaskan tundra is expected to increase under all three climate scenarios. Occurrences of high fire weather danger (>10 FWI) are projected to increase in frequency and magnitude in all regions modeled. The changes in fire weather conditions are expected to vary from one region to another in seasonal occurrence as well as severity and frequency of high fire weather danger. While the Alaska Large Fire Database represents the best data available for the Alaskan Arctic, and is superior to many other regions around the world, particularly Arctic regions, these fire records need to be used with some caution due to the mixed origin and minimal validation of the data; this is reviewed in the presentation.

Assessing Landscape Scale Wildfire Exposure for Highly Valued Resources in a Mediterranean Area

NASA Astrophysics Data System (ADS)

Alcasena, Fermín J.; Salis, Michele; Ager, Alan A.; Arca, Bachisio; Molina, Domingo; Spano, Donatella

2015-05-01

We used a fire simulation modeling approach to assess landscape scale wildfire exposure for highly valued resources and assets (HVR) on a fire-prone area of 680 km2 located in central Sardinia, Italy. The study area was affected by several wildfires in the last half century: some large and intense fire events threatened wildland urban interfaces as well as other socioeconomic and cultural values. Historical wildfire and weather data were used to inform wildfire simulations, which were based on the minimum travel time algorithm as implemented in FlamMap. We simulated 90,000 fires that replicated recent large fire events in the area spreading under severe weather conditions to generate detailed maps of wildfire likelihood and intensity. Then, we linked fire modeling outputs to a geospatial risk assessment framework focusing on buffer areas around HVR. The results highlighted a large variation in burn probability and fire intensity in the vicinity of HVRs, and allowed us to identify the areas most exposed to wildfires and thus to a higher potential damage. Fire intensity in the HVR buffers was mainly related to fuel types, while wind direction, topographic features, and historically based ignition pattern were the key factors affecting fire likelihood. The methodology presented in this work can have numerous applications, in the study area and elsewhere, particularly to address and inform fire risk management, landscape planning and people safety on the vicinity of HVRs.

Normalized burn ratios link fire severity with patterns of avian occurrence

USGS Publications Warehouse

Rose, Eli T.; Simons, Theodore R.; Klein, Rob; McKerrow, Alexa

2016-01-01

ContextRemotely sensed differenced normalized burn ratios (DNBR) provide an index of fire severity across the footprint of a fire. We asked whether this index was useful for explaining patterns of bird occurrence within fire adapted xeric pine-oak forests of the southern Appalachian Mountains.ObjectivesWe evaluated the use of DNBR indices for linking ecosystem process with patterns of bird occurrence. We compared field-based and remotely sensed fire severity indices and used each to develop occupancy models for six bird species to identify patterns of bird occurrence following fire.MethodsWe identified and sampled 228 points within fires that recently burned within Great Smoky Mountains National Park. We performed avian point counts and field-assessed fire severity at each bird census point. We also used Landsat™ imagery acquired before and after each fire to quantify fire severity using DNBR. We used non-parametric methods to quantify agreement between fire severity indices, and evaluated single season occupancy models incorporating fire severity summarized at different spatial scales.ResultsAgreement between field-derived and remotely sensed measures of fire severity was influenced by vegetation type. Although occurrence models using field-derived indices of fire severity outperformed those using DNBR, summarizing DNBR at multiple spatial scales provided additional insights into patterns of occurrence associated with different sized patches of high severity fire.ConclusionsDNBR is useful for linking the effects of fire severity to patterns of bird occurrence, and informing how high severity fire shapes patterns of bird species occurrence on the landscape.

Pinus contorta invasions increase wildfire fuel loads and may create a positive feedback with fire.

PubMed

Taylor, Kimberley T; Maxwell, Bruce D; McWethy, David B; Pauchard, Aníbal; Nuñez, Martín A; Whitlock, Cathy

2017-03-01

Invasive plant species that have the potential to alter fire regimes have significant impacts on native ecosystems. Concern that pine invasions in the Southern Hemisphere will increase fire activity and severity and subsequently promote further pine invasion prompted us to examine the potential for feedbacks between Pinus contorta invasions and fire in Patagonia and New Zealand. We determined how fuel loads and fire effects were altered by P. contorta invasion. We also examined post-fire plant communities across invasion gradients at a subset of sites to assess how invasion alters the post-fire vegetation trajectory. We found that fuel loads and soil heating during simulated fire increase with increasing P. contorta invasion age or density at all sites. However, P. contorta density did not always increase post-fire. In the largest fire, P. contorta density only increased significantly post-fire where the pre-fire P. contorta density was above an invasion threshold. Below this threshold, P. contorta did not dominate after fire and plant communities responded to fire in a similar manner as uninvaded communities. The positive feedback observed at high densities is caused by the accumulation of fuel that in turn results in greater soil heating during fires and high P. contorta density post-fire. Therefore, a positive feedback may form between P. contorta invasions and fire, but only above an invasion density threshold. These results suggest that management of pine invasions before they reach the invasion density threshold is important for reducing fire risk and preventing a transition to an alternate ecosystem state dominated by pines and novel understory plant communities. © 2016 by the Ecological Society of America.

Fires: Pushing the Reset Button or a Flash in the Pan?

NASA Astrophysics Data System (ADS)

MacDonald, L. H.; Wagenbrenner, J. W.; Robichaud, P. R.; Nelson, P. A.; Kampf, S. K.; Brogan, D. J.

2016-12-01

High and moderate severity wildfires can reduce infiltration rates to less than 10 mm/hr, and the resulting surface runoff can increase small-scale peak flows by one or more orders of magnitude. Fires can increase hillslope erosion rates by several orders of magnitude, but this increase is less linear with rainfall intensity because it also depends on sediment supply and detachment processes as well as transport capacity. These localized and shorter-term effects have been relatively well documented, but there is much more uncertainty in how these fire-induced changes can lead to larger-scale and/or longer-term effects. The goal of this presentation is to provide a process-based analysis of how, where, and when wildfires can cause either longer-term or larger-scale changes, effectively resetting the system as opposed to a more transient "flash in the pan". An understanding of vegetation, climatic, and geomorphic dynamics are are critical for predicting larger-scale and longer-term effects. First is the potential for the vegetation to return to pre-fire conditions, and this depends on vegetation type, spatial extent of the fire, and if the pre-fire vegetation is marginalized by climate change, land use, or other factors. The trajectory of post-fire regrowth controls the duration of increased runoff and erosion as well as the size and severity of future fires, which then sets the scene for longer-term hydrologic and geomorphic change. Climate defines the dominant storm type and how they match up with the spatial extent of a fire. Historic data help estimate the extent and magnitude of post-fire rainfall, but there is a strong stochastic component and the more extreme events are of greatest concern. Geomorphic controls on larger-scale effects include the valley and drainage network characteristics that help govern the storage and delivery of water and sediment. Assessing each component involves multiple site factors, but the biggest problem is understanding their complex interactions to predict resource impacts, landscape change over different temporal and spatial scales, and the potential to ameliorate adverse impacts. Data from multiple field studies are used to illustrate the range of post-fire effects, selected interactions of the different components, and identify key research needs.

Fire severity is more sensitive to low fuel moisture content on Calluna heathlands than on peat bogs.

PubMed

Grau-Andrés, Roger; Davies, G Matt; Gray, Alan; Scott, E Marian; Waldron, Susan

2018-03-01

Moorland habitats dominated by the dwarf shrub Calluna vulgaris provide important ecosystem services. Drought is projected to intensify throughout their range, potentially leading to increased fire severity as moisture is a key control on severity. We studied the effect of low fuel moisture content (FMC) on fire severity by using 2×2m rain-out shelters prior to completing 19 experimental fires in two sites in Scotland (UK): a dry heath with thin organic soils and a raised bog with deep, saturated peat, both dominated by Calluna vulgaris. Reduced FMC of the moss and litter (M/L) layer at both sites, and the soil moisture of the dry heath, increased fire-induced consumption of the M/L layer and soil heating at both sites. Increase in fire severity was greater at the dry heath than at the raised bog, e.g. average maximum temperatures at the soil surface increased from 31°C to 189°C at the dry heath, but only from 10°C to 15°C at the raised bog. Substantial M/L layer consumption was observed when its FMC was below 150%. This led to larger seasonal and daily soil temperature fluctuation, particularly at the dry heath during warm months. The results suggest that low FMC following predicted changes in climate are likely to increase wildfire severity and that the impact on vegetation composition and carbon stores may be greater at heathlands than at peatlands. Managed burning aiming to minimise fire severity (e.g. ignition of the M/L layer and exposure to lethal temperatures of ericoid seeds) should be carried out when the FMC of the M/L layer is above 150% and the FMC of the soil is above 200-300%. Copyright © 2017 Elsevier B.V. All rights reserved.

Risk preferences in strategic wildfire decision making: a choice experiment with U.S. wildfire managers.

PubMed

Wibbenmeyer, Matthew J; Hand, Michael S; Calkin, David E; Venn, Tyron J; Thompson, Matthew P

2013-06-01

Federal policy has embraced risa management as an appropriate paradigm for wildfire management. Economic theory suggests that over repeated wildfire events, potential economic costs and risas of ecological damage are optimally balanced when management decisions are free from biases, risa aversion, and risa seeking. Of primary concern in this article is how managers respond to wildfire risa, including the potential effect of wildfires (on ecological values, structures, and safety) and the likelihood of different fire outcomes. We use responses to a choice experiment questionnaire of U.S. federal wildfire managers to measure attitudes toward several components of wildfire risa and to test whether observed risa attitudes are consistent with the efficient allocation of wildfire suppression resources. Our results indicate that fire managers' decisions are consistent with nonexpected utility theories of decisions under risa. Managers may overallocate firefighting resources when the likelihood or potential magnitude of damage from fires is low, and sensitivity to changes in the probability of fire outcomes depends on whether probabilities are close to one or zero and the magnitude of the potential harm. © 2012 Society for Risk Analysis.

Short-term low-severity spring grassland fire impacts on soil extractable elements and soil ratios in Lithuania.

PubMed

Pereira, Paulo; Cerda, Artemi; Martin, Deborah; Úbeda, Xavier; Depellegrin, Daniel; Novara, Agata; Martínez-Murillo, Juan F; Brevik, Eric C; Menshov, Oleksandr; Comino, Jesus Rodrigo; Miesel, Jessica

2017-02-01

Spring grassland fires are common in boreal areas as a consequence of slash and burn agriculture used to remove dry grass to increase soil nutrient properties and crop production. However, few works have investigated fire impacts on these grassland ecosystems, especially in the immediate period after the fire. The objective of this work was to study the short-term impacts of a spring grassland fire in Lithuania. Four days after the fire we established a 400m 2 sampling grid within the burned area and in an adjacent unburned area with the same topographical, hydrological and pedological characteristics. We collected topsoil samples immediately after the fire (0months), 2, 5, 7 and 9months after the fire. We analysed soil pH, electrical conductivity (EC), major nutrients including calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K), and the minor elements aluminium (Al), manganese (Mn), iron (Fe) and zinc (Zn). We also calculated the soil Na and K adsorption ratio (SPAR), Ca:Mg and Ca:Al. The results showed that this low-severity grassland fire significantly decreased soil pH, Al, and Mn but increased EC, Ca, Mg, and K,. There was no effect on Na, Fe, and Zn. There was a decrease of EC, Ca, Mg, and Na from 0months after the fire until 7months after the fire, with an increase during the last sampling period. Fire did not significantly affect SPAR. Ca:Mg decreased significantly immediately after the fire, but not to critical levels. Ca:Al increased after the fire, reducing the potential effects of Al on plants. Overall, fire impacts were mainly limited to the immediate period after the fire. Copyright © 2016 Elsevier B.V. All rights reserved.

Fire frequency, area burned, and severity: A quantitative approach to defining a normal fire year

USGS Publications Warehouse

Lutz, J.A.; Key, C.H.; Kolden, C.A.; Kane, J.T.; van Wagtendonk, J.W.

2011-01-01

Fire frequency, area burned, and fire severity are important attributes of a fire regime, but few studies have quantified the interrelationships among them in evaluating a fire year. Although area burned is often used to summarize a fire season, burned area may not be well correlated with either the number or ecological effect of fires. Using the Landsat data archive, we examined all 148 wildland fires (prescribed fires and wildfires) >40 ha from 1984 through 2009 for the portion of the Sierra Nevada centered on Yosemite National Park, California, USA. We calculated mean fire frequency and mean annual area burned from a combination of field- and satellite-derived data. We used the continuous probability distribution of the differenced Normalized Burn Ratio (dNBR) values to describe fire severity. For fires >40 ha, fire frequency, annual area burned, and cumulative severity were consistent in only 13 of 26 years (50 %), but all pair-wise comparisons among these fire regime attributes were significant. Borrowing from long-established practice in climate science, we defined "fire normals" to be the 26 year means of fire frequency, annual area burned, and the area under the cumulative probability distribution of dNBR. Fire severity normals were significantly lower when they were aggregated by year compared to aggregation by area. Cumulative severity distributions for each year were best modeled with Weibull functions (all 26 years, r2 ??? 0.99; P < 0.001). Explicit modeling of the cumulative severity distributions may allow more comprehensive modeling of climate-severity and area-severity relationships. Together, the three metrics of number of fires, size of fires, and severity of fires provide land managers with a more comprehensive summary of a given fire year than any single metric.

Prediction and Mitigation of the Effects of Catastrophic Fire on Water Supplies: Science for Risk Reduction and Planning for Future Scenarios

NASA Astrophysics Data System (ADS)

Martin, D. A.; Tindall, J.

2008-12-01

Precipitation falling on forests and grasslands provides much of the water to communities across the United States. The U.S. Forest Service estimates that over 3,400 communities are served by water draining land under its jurisdiction alone. Much of this land is subject to wildland fires, which have been increasing in size and severity in the western United States in response to climatic forcing and increased ignitions from human sources. Runoff from burned landscapes can present a significant risk to municipal and agricultural water supplies from ash, sediment, contaminants from burned structures, and fire-fighting chemicals. Several municipalities, including Denver, Colorado, have experienced both short-term and long-term degradation of their water supplies in the aftermath of fires in watersheds upstream from drinking water reservoirs. Scientific efforts to predict and mitigate the effects of catastrophic fire on water supplies have focused on three areas. The first consists of data collection and carefully designed experiments to understand the change of the hydrologic behavior of burned watersheds in response to rain with different intensities, durations, and trajectories as the watersheds recover. Results from these studies are used to validate models that predict watershed response under different initial conditions constrained by remotely-sensed burn severity, topography, rainfall-intensity recurrence probabilities and other factors. These predictions are the basis for rehabilitation measures applied to the landscape to minimize post-fire runoff and erosion. Efforts are under way to incorporate the chemical effects of ash and fire-fighting compounds in decision-support tools. A second area of scientific focus is the characterization of the chemical and physical properties of ash from wildland fire, including ash from structures consumed by fire. The ash chemistry is correlated to remotely- sensed data, type of vegetation that burned, and the underlying geology. Ash affects the hydraulic properties and behavior of soils in burned watersheds while it still mantles the hillslopes, but it is easily delivered to water bodies by rain and wind as a flush of material that affects water chemistry and properties like turbidity and temperature. A third thrust is to identify watersheds that are critical to the function of municipal water supplies and infrastructure to determine their vulnerability to fire and post-fire effects. This information can be used to prioritize areas for fuel treatments or land management practices to minimize the probability of high severity fire and hence the effects of post-fire runoff. Scientific studies are providing crucial information about such topics as changes in soil erodibility, infiltration and runoff after fire, and the effects of vegetation recovery. Even in watersheds where land management actions are limited by topography or land use designation, such as wilderness areas, knowledge of the potential response of burned areas allows water providers to develop rapid-response and long-term plans based on scientific data and tools. Some climate change models are predicting hotter, drier temperatures in certain areas of the United States and a higher probability of larger, more severe wildfires. These predictions have a direct bearing on the potential risk of impairment of water supplies by post-fire runoff and erosion. In an era when water availability and quality are of utmost importance, careful scientific studies focused on the effects of wildland fire on water supplies will continue to inform public policy and decision making on topics of vulnerability and risk reduction.

Fire severity and tree regeneration following bark beetle outbreaks: the role of outbreak stage and burning conditions.

PubMed

Harvey, Brian J; Donato, Daniel C; Romme, William H; Turner, Monica G

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 against prefire outbreak severity. In the green-attack/red stage, several canopy fire-severity measures increased with prefire outbreak severity under moderate burning conditions. Under extreme conditions, few fire-severity measures were related to prefire outbreak severity, and effect sizes were of marginal biological significance. The percentage of tree stems and basal area killed by fire increased with more green-attack vs. red-stage trees (i.e., the earliest stages of outbreak). In the gray stage, by contrast, most fire-severity measures declined with increasing outbreak severity under moderate conditions, and fire severity was unrelated to outbreak severity under extreme burning conditions. Postfire lodgepole pine seedling regeneration was unrelated to prefire outbreak severity in either post-outbreak stage, but increased with prefire serotiny. Results suggest bark beetle outbreaks can affect fire severity in subalpine forests under moderate burning conditions, but have little effect on fire severity under extreme burning conditions when most large wildfires occur in this system. Thus, beetle outbreak severity was moderately linked to fire severity, but the strength and direction of the linkage depended on both endogenous (outbreak stage) and exogenous (fire weather) factors. Closely timed beetle outbreak and fire did not impart compound effects on tree regeneration, suggesting the presence of a canopy seedbank may enhance resilience to their combined effects.

Simulation of air quality impacts from prescribed fires on an urban area.

PubMed

Hu, Yongtao; Odman, M Talat; Chang, Michael E; Jackson, William; Lee, Sangil; Edgerton, Eric S; Baumann, Karsten; Russell, Armistead G

2008-05-15

On February 28, 2007, a severe smoke event caused by prescribed forest fires occurred in Atlanta, GA. Later smoke events in the southeastern metropolitan areas of the United States caused by the Georgia-Florida wild forest fires further magnified the significance of forest fire emissions and the benefits of being able to accurately predict such occurrences. By using preburning information, we utilize an operational forecasting system to simulate the potential air quality impacts from two large February 28th fires. Our "forecast" predicts that the scheduled prescribed fires would have resulted in over 1 million Atlanta residents being potentially exposed to fine particle matter (PM2.5) levels of 35 microg m(-3) or higher from 4 p.m. to midnight. The simulated peak 1 h PM2.5 concentration is about 121 microg m(-3). Our study suggests that the current air quality forecasting technology can be a useful tool for helping the management of fire activities to protect public health. With postburning information, our "hindcast" predictions improved significantly on timing and location and slightly on peak values. "Hindcast" simulations also indicated that additional isoprenoid emissions from pine species temporarily triggered by the fire could induce rapid ozone and secondary organic aerosol formation during late winter. Results from this study suggest that fire induced biogenic volatile organic compounds emissions missing from current fire emissions estimate should be included in the future.

Geophysical survey for groundwater potential investigation in peat land area, Riau, Indonesia

NASA Astrophysics Data System (ADS)

Islami, N.; Irianti, M.; Azhar; Nor, M.; Fakhrudin

2018-04-01

Tropical forests, especially peat lands, are particularly vulnerable to forest fires. Fires are the most common disasters in peat lands in the dry season, especially in Riau Province, Indonesia. In the process of extinguishing the peat fire, several substantial problems arise to stop peat fires during this period. This study aims to determine the possibility of using ground water as a source of water to anticipate the early mitigation of peat land fires disaster. The geoelectrical resistivity surveys were used to predict the subsurface geological data including peat thickness and depth of aquifers. The geometry of peat lands was determined using geostatistics based on geoelectrical resistivity interpretation data. Peat Land thickness varies up to 4 m in the north and is thinner to the south. A shallower and deeper aquifer is available at a depth of 13 m to 18 m and 70 m to 90 m respectively. In general, the potential of groundwater in the shallow aquifer is predicted to be sufficient for peat land watering anytime.

Extreme Fire Severity Patterns in Topographic, Convective and Wind-Driven Historical Wildfires of Mediterranean Pine Forests

PubMed Central

Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

2014-01-01

Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme severity wildfires. PMID:24465492

Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of Mediterranean pine forests.

PubMed

Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

2014-01-01

Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme severity wildfires.

Factors associated with the severity of interacting fires in Yosemite National Park

USGS Publications Warehouse

van Wagtendonk, Jan W.; van Wagtendonk, Kent A.; Thode, Andrea E.

2012-01-01

In 1972, Yosemite National Park established a wilderness fire zone in which lightning fires were allowed to run their courses under prescribed conditions. This zone was expanded in 1973 to include the 16 209 ha Illilouette Creek basin, just to the southeast of Yosemite Valley. From 1973 through 2011, there have been 157 fires in the basin. Fire severity data were collected on all 28 of those fires that were larger than 40 ha. The proportion burned in each fire severity class was not significantly associated with fire return interval departure class. When areas were reburned, the proportion of unchanged severity fire decreased while the proportion of high severity fire increased. The proportion of fire severity of the subsequent fires was associated with the number of years since last burned, the burning index, and the severity of the previous fires. The main effects were significant for unchanged severity and low severity, and the interaction between return interval class and burning index class was significant for high severity. Most vegetation types remained the same when burned with unchanged, low, or moderate severity, while high severity often resulted in conversion to montane chaparral. The factors that were associated with reburn severity worked in combination with each factor influencing some aspect of severity. Managers and scientists can use this information to better understand the role fire plays in these ecosystems and how to best manage this dynamic ecological process.

Fire severity and ecosytem responses following crown fires in California shrublands

USGS Publications Warehouse

Keeley, J.E.; Brennan, T.; Pfaff, A.H.

2008-01-01

Chaparral shrublands burn in large high-intensity crown fires. Managers interested in how these wildfires affect ecosystem processes generally rely on surrogate measures of fire intensity known as fire severity metrics. In shrublands burned in the autumn of 2003, a study of 250 sites investigated factors determining fire severity and ecosystem responses.Using structural equation modeling we show that stand age, prefire shrub density, and the shortest interval of the prior fire history had significant direct effects on fire severity, explaining >50% of the variation in severity.Fire severity per se is of interest to resource managers primarily because it is presumed to be an indicator of important ecosystem processes such as vegetative regeneration, community recovery, and erosion. Fire severity contributed relatively little to explaining patterns of regeneration after fire. Two generalizations can be drawn: fire severity effects are mostly short-lived, i.e., by the second year they are greatly diminished, and fire severity may have opposite effects on different functional types.Species richness exhibited a negative relationship to fire severity in the first year, but fire severity impacts were substantially less in the second postfire year and varied by functional type. Much of this relationship was due to alien plants that are sensitive to high fire severity; at all scales from 1 to 1000 m2, the percentage of alien species in the postfire flora declined with increased fire severity. Other aspects of disturbance history are also important determinants of alien cover and richness as both increased with the number of times the site had burned and decreased with time since last fire.A substantial number of studies have shown that remote-sensing indices are correlated with field measurements of fire severity. Across our sites, absolute differenced normalized burn ratio (dNBR) was strongly correlated with field measures of fire severity and with fire history at a site but relative dNBR was not. Despite being correlated with fire severity, absolute dNBR showed little or no relationship with important ecosystem responses to wildfire such as shrub resprouting or total vegetative regeneration. These findings point to a critical need for further research on interpreting remote sensing indices as applied to postfire management of these shrublands.

Fire severity and ecosytem responses following crown fires in California shrublands.

PubMed

Keeley, Jon E; Brennan, Teresa; Pfaff, Anne H

2008-09-01

Chaparral shrublands burn in large high-intensity crown fires. Managers interested in how these wildfires affect ecosystem processes generally rely on surrogate measures of fire intensity known as fire severity metrics. In shrublands burned in the autumn of 2003, a study of 250 sites investigated factors determining fire severity and ecosystem responses. Using structural equation modeling we show that stand age, prefire shrub density, and the shortest interval of the prior fire history had significant direct effects on fire severity, explaining > 50% of the variation in severity. Fire severity per se is of interest to resource managers primarily because it is presumed to be an indicator of important ecosystem processes such as vegetative regeneration, community recovery, and erosion. Fire severity contributed relatively little to explaining patterns of regeneration after fire. Two generalizations can be drawn: fire severity effects are mostly shortlived, i.e., by the second year they are greatly diminished, and fire severity may have opposite effects on different functional types. Species richness exhibited a negative relationship to fire severity in the first year, but fire severity impacts were substantially less in the second postfire year and varied by functional type. Much of this relationship was due to alien plants that are sensitive to high fire severity; at all scales from 1 to 1000 m2, the percentage of alien species in the postfire flora declined with increased fire severity. Other aspects of disturbance history are also important determinants of alien cover and richness as both increased with the number of times the site had burned and decreased with time since last fire. A substantial number of studies have shown that remote-sensing indices are correlated with field measurements of fire severity. Across our sites, absolute differenced normalized burn ratio (dNBR) was strongly correlated with field measures of fire severity and with fire history at a site but relative dNBR was not. Despite being correlated with fire severity, absolute dNBR showed little or no relationship with important ecosystem responses to wildfire such as shrub resprouting or total vegetative regeneration. These findings point to a critical need for further research on interpreting remote sensing indices as applied to postfire management of these shrublands.

Seasonal and diurnal variation in moisture content of six species of pocosin shrubs

Treesearch

W. H. Blackmarr; William B. Flanner

1968-01-01

Understory shrubs growing on organic soils in pocosins of the eastern North Carolina coastal plain can become a particularly severe fire hazard during certain dry seasons of the year. These shrubs commonly form dense thickets of highly flammable fuels capable of supporting very intense wildfires. Such fires, once started, often have the potential for widespread...

Modeling potential outcomes of fire and fuel management scenarios on the structure of forested habitats in northeast Oregon, USA.

Treesearch

B.C. Wales; L.H. Suring; M.A. Hemstrom

2007-01-01

Thinning and prescribed fire are being used extensively across the interior Western United States to reduce the risk of large, severe wildfires. However, the full ecological consequences of implementing these management practices on the landscape have not been completely evaluated. We projected future vegetation trends resulting from four management scenarios and...

Effect of a Spaced Thinning in Mature Lodgepole Pine on Within-Stand Microclimate and Fine Fuel Moisture Content

Treesearch

R. J. Whitehead; G. L. Russo; B. C. Hawkes; S. W. Taylor; B. N. Brown; H. J. Barclay; R. A. Benton

2006-01-01

Thinning mature forest stands to wide spacing is prescribed to reduce crown bulk density and likelihood of severe crown fire behaviour. However, it may adversely affect surface fuel load, moisture content and within-stand wind, which influence surface fire behaviour and crowning potential. Comparison of a mature lodgepole pine (Pinus contorta Dougl....

Using Shelterwood Harvests and Prescribed Fire to Regenerate Oak Stands on Productive Upland Sites

Treesearch

Patrick H. Brose; David H. van Lear; Roderick Cooper

1999-01-01

Regenerating oak stands on productive upland sites in the Piedmont region is a major problem because of intense competition from yellow-poplar. As a potential solution to this problem, we tested the hypothesis that a shelterwood harvest of an oak-dominated stand. followed several years later by a prescribed fire, would adequately regeneraie the stand. Three oak-...

Effects of bark beetle attack on canopy fuel flammability and crown fire potential in lodgepole pine and Engelmann spruce forests

Treesearch

Wesley G. Page; Martin E. Alexander; Michael J. Jenkins

2015-01-01

Large wildland fires in conifer forests typically involve some degree of crowning, with their initiation and propagation dependent upon several characteristics of the canopy fuels. Recent outbreaks of mountain pine beetle (Dendroctonus ponderosae Hopkins) in lodgepole pine (Pinus contorta Dougl. var. latifolia E ngelm.) forests and spruce beetle (Dendroctonus...

A fuel treatment reduces fire severity and increases suppression efficiency in a mixed conifer forest

Treesearch

Jason J. Moghaddas; Larry Craggs

2007-01-01

Fuel treatments are being implemented on public and private lands across the western United States. Although scientists and managers have an understanding of how fuel treatments can modify potential fire behaviour under modelled conditions, there is limited information on how treatments perform under real wildfire conditions in Sierran mixed conifer forests. The Bell...

Impacts of fire on non-native plant recruitment in black spruce forests of interior Alaska.

PubMed

Walker, Xanthe J; Frey, Matthew D; Conway, Alexandra J; Jean, Mélanie; Johnstone, Jill F

2017-01-01

Climate change is expected to increase the extent and severity of wildfires throughout the boreal forest. Historically, black spruce (Picea mariana (Mill.) B.S.P.) forests in interior Alaska have been relatively free of non-native species, but the compounding effects of climate change and an altered fire regime could facilitate the expansion of non-native plants. We tested the effects of wildfire on non-native plant colonization by conducting a seeding experiment of non-native plants on different substrate types in a burned black spruce forest, and surveying for non-native plants in recently burned and mature black spruce forests. We found few non-native plants in burned or mature forests, despite their high roadside presence, although invasion of some burned sites by dandelion (Taraxacum officinale) indicated the potential for non-native plants to move into burned forest. Experimental germination rates were significantly higher on mineral soil compared to organic soil, indicating that severe fires that combust much of the organic layer could increase the potential for non-native plant colonization. We conclude that fire disturbances that remove the organic layer could facilitate the invasion of non-native plants providing there is a viable seed source and dispersal vector.

Effects of fire disturbance on soil respiration in the non-growing season in a Larix gmelinii forest in the Daxing'an Mountains, China.

PubMed

Hu, Tongxin; Sun, Long; Hu, Haiqing; Guo, Futao

2017-01-01

In boreal forests, fire is an important part of the ecosystem that greatly influences soil respiration, which in turn affects the carbon balance. Wildfire can have a significant effect on soil respiration and it depends on the fire severity and environmental factors (soil temperature and snow water equivalent) after fire disturbance. In this study, we quantified post-fire soil respiration during the non-growing season (from November to April) in a Larix gmelinii forest in Daxing'an Mountains of China. Soil respiration was measured in the snow-covered and snow-free conditions with varying degrees of natural burn severity forests. We found that soil respiration decreases as burn severity increases. The estimated annual C efflux also decreased with increased burn severity. Soil respiration during the non-growing season approximately accounted for 4%-5% of the annual C efflux in all site types. Soil temperature (at 5 cm depth) was the predominant determinant of non-growing season soil respiration change in this area. Soil temperature and snow water equivalent could explain 73%-79% of the soil respiration variability in winter snow-covering period (November to March). Mean spring freeze-thaw cycle (FTC) period (April) soil respiration contributed 63% of the non-growing season C efflux. Our finding is key for understanding and predicting the potential change in the response of boreal forest ecosystems to fire disturbance under future climate change.

Effects of fire disturbance on soil respiration in the non-growing season in a Larix gmelinii forest in the Daxing'an Mountains, China

PubMed Central

Hu, Tongxin; Guo, Futao

2017-01-01

In boreal forests, fire is an important part of the ecosystem that greatly influences soil respiration, which in turn affects the carbon balance. Wildfire can have a significant effect on soil respiration and it depends on the fire severity and environmental factors (soil temperature and snow water equivalent) after fire disturbance. In this study, we quantified post-fire soil respiration during the non-growing season (from November to April) in a Larix gmelinii forest in Daxing'an Mountains of China. Soil respiration was measured in the snow-covered and snow-free conditions with varying degrees of natural burn severity forests. We found that soil respiration decreases as burn severity increases. The estimated annual C efflux also decreased with increased burn severity. Soil respiration during the non-growing season approximately accounted for 4%–5% of the annual C efflux in all site types. Soil temperature (at 5 cm depth) was the predominant determinant of non-growing season soil respiration change in this area. Soil temperature and snow water equivalent could explain 73%–79% of the soil respiration variability in winter snow-covering period (November to March). Mean spring freeze–thaw cycle (FTC) period (April) soil respiration contributed 63% of the non-growing season C efflux. Our finding is key for understanding and predicting the potential change in the response of boreal forest ecosystems to fire disturbance under future climate change. PMID:28665958

Induction of antimicrobial 3-deoxyflavonoids in pome fruit trees controls fire blight.

PubMed

Halbwirth, Heidrun; Fischer, Thilo C; Roemmelt, Susanne; Spinelli, Francesco; Schlangen, Karin; Peterek, Silke; Sabatini, Emidio; Messina, Christian; Speakman, John-Bryan; Andreotti, Carlo; Rademacher, Wilhelm; Bazzi, Carlo; Costa, Guglielmo; Treutter, Dieter; Forkmann, Gert; Stich, Karl

2003-01-01

Fire blight, a devastating bacterial disease in pome fruits, causes severe economic losses worldwide. Hitherto, an effective control could only be achieved by using antibiotics, but this implies potential risks for human health, livestock and environment. A new approach allows transient inhibition of a step in the flavonoid pathway, thereby inducing the formation of a novel antimicrobial 3-deoxyflavonoid controlling fire blight in apple and pear leaves. This compound is closely related to natural phytoalexins in sorghum. The approach does not only provide a safe method to control fire blight: Resistance against different pathogens is also induced in other crop plants.

Ecological responses to el Niño-induced surface fires in central Brazilian Amazonia: management implications for flammable tropical forests.

PubMed Central

Barlow, Jos; Peres, Carlos A

2004-01-01

Over the past 20 years the combined effects of El Niño-induced droughts and land-use change have dramatically increased the frequency of fire in humid tropical forests. Despite the potential for rapid ecosystem alteration and the current prevalence of wildfire disturbance, the consequences of such fires for tropical forest biodiversity remain poorly understood. We provide a pan-tropical review of the current state of knowledge of these fires, and include data from a study in a seasonally dry terra firme forest of central Brazilian Amazonia. Overall, this study supports predictions that rates of tree mortality and changes in forest structure are strongly linked to burn severity. The potential consequences for biomass loss and carbon emissions are explored. Despite the paucity of data on faunal responses to tropical forest fires, some trends are becoming apparent; for example, large canopy frugivores and understorey insectivorous birds appear to be highly sensitive to changes in forest structure and composition during the first 3 years after fires. Finally, we appraise the management implications of fires and evaluate the viability of techniques and legislation that can be used to reduce forest flammability, prevent anthropogenic ignition sources from coming into contact with flammable forests and aid the post-fire recovery process. PMID:15212091

Review of Repair Materials for Fire-Damaged Reinforced Concrete Structures

NASA Astrophysics Data System (ADS)

Zahid, MZA Mohd; Abu Bakar, BH; Nazri, FM; Ahmad, MM; Muhamad, K.

2018-03-01

Reinforced concrete (RC) structures perform well during fire and may be repaired after the fire incident because their low heat conductivity prevents the loss or degradation of mechanical strength of the concrete core and internal reinforcing steel. When an RC structure is heated to more than 500 °C, mechanical properties such as compressive strength, stiffness, and tensile strength start to degrade and deformations occur. Although the fire-exposed RC structure shows no visible damage, its residual strength decreases compared with that in the pre-fire state. Upon thorough assessment, the fire-damaged RC structure can be repaired or strengthened, instead of subjecting to partial or total demolition followed by reconstruction. The structure can be repaired using several materials, such as carbon fiber-reinforced polymer, glass fiber-reinforced polymer, normal strength concrete, fiber-reinforced concrete, ferrocement, epoxy resin mortar, and high-performance concrete. Selecting an appropriate repair material that must be compatible with the substrate or base material is a vital step to ensure successful repair. This paper reviews existing repair materials and factors affecting their performance. Of the materials considered, ultra-high-performance fiber-reinforced concrete (UHPFRC) exhibits huge potential for repairing fire-damaged RC structures but lack of information available. Hence, further studies must be performed to assess the potential of UHPFRC in rehabilitating fire-damaged RC structures.

Modeling Fire Emissions across Central and Southern Italy: Implications for Land and Fire Management

NASA Astrophysics Data System (ADS)

Bacciu, V. M.; Salis, M.; Spano, D.

2015-12-01

Fires play a relevant role in the global and regional carbon cycle, representing a remarkable source of CO2 and other greenhouse gases (GHG) that influence atmosphere budgets and climate. In addition, the wildfire increase projected in Southern Europe due to climate change (CC) and concurrent exacerbation of extreme weather conditions could also lead to a significant rise in GHG. Recently, in the context of the Italian National Adaptation Strategy to Climate Change (SNAC), several approaches were identified as valuable tools to adapt and mitigate the impacts of CC on wildfires, in order to reduce landscape susceptibility and to contribute to the efforts of carbon emission mitigation proposed within the Kyoto protocol. Active forest and fuel management (such as prescribed burning, fuel reduction and removal, weed and flammable shrub control, creation of fuel discontinuity) is recognised to be a key element to adapt and mitigate the impacts of CC on wildfires. Despite this, overall there is a lack of studies about the effectiveness of fire emission mitigation strategies. The current work aims to analyse the potential of a combination of fuel management practices in mitigating emissions from forest fires and evaluate valuable and viable options across Central and Southern Italy. These objectives were achieved throughout a retrospective application of an integrated approach combining a fire emission model (FOFEM - First Order Fire Effect Model) with spatially explicit, comprehensive, and accurate fire, vegetation and weather data for the period 2004-2012. Furthermore, a number of silvicultural techniques were combined to develop several fuel management scenarios and then tested to evaluate their potential in mitigating fire emissions.The preliminary results showed the crucial role of appropriate fuel, fire behavior, and weather data to reduce bias in quantifying the source and the composition of fire emissions and to attain reasonable estimations. Also, the current study highlighted that balanced combination of fuel management techniques could not only be a viable mean to reduce fire emissions but at the same time prevent future wildfires and the related threat to human lives and activities.

Post-fire Water Quality in the Western United States: Understanding and Predicting Short and Long-term Response

NASA Astrophysics Data System (ADS)

Hogue, T. S.; Rust, A.

2016-12-01

Fire frequency is increasing across mid-elevation forests, especially in the Northern Rockies, Sierra Nevada, southern Cascades, as well as the coastal ranges in California and southern Oregon. Numerous studies have noted increased discharge, floods and debris flows after wildfire. More recent work also shows increased water yield during dry seasons for up to ten years post-fire. However, few studies have evaluated long-term water quality response in fire-impacted watersheds. The current presentation will overview recent development of an extensive database on post-fire water quality response across the western U.S. A range of water quality parameters were gathered from 271 burned watersheds through local, state and federal agencies. Short and long-term response was evaluated for watersheds with at least 5 years of pre-fire data. Over 30 watersheds showed significant increases in NO3-, NO2-, NH3, and total nitrogen loading in the initial five years after fire and remained elevated ten years after fire. The burn severity influenced the degree of nitrogen response, where more severely burned watersheds showed higher nitrogen loading than less severely burned watersheds. Dissolved and total phosphorous showed significant increases in 32 watersheds for the first five years after fire. Dissolved ions such as calcium, magnesium, and chloride were also exported from over 32 watersheds, primarily during the first five years after fire, with the majority of impacted watersheds returning to pre-fire water quality conditions after ten years. Ongoing work includes evaluating key determinants that drive short and long-term response and developing predictive models for post-fire water quality. Watersheds impacted by wildfire are known to pose significant risks for downstream communities. Understanding short and long-term water quality change that can impact regional water supplies is critical for establishing potential treatment priorities and alternative source planning.

Satellite-based Assessment of Climate Controls on US Burned Area

NASA Technical Reports Server (NTRS)

Morton, D. C.; Collatz, G. J.; Wang, D.; Randerson, J. T.; Giglio, L.; Chen, Y.

2012-01-01

Climate regulates fire activity through the buildup and drying of fuels and the conditions for fire ignition and spread. Understanding the dynamics of contemporary climate-fire relationships at national and sub-national scales is critical to assess the likelihood of changes in future fire activity and the potential options for mitigation and adaptation. Here, we conducted the first national assessment of climate controls on US fire activity using two satellite-based estimates of monthly burned area (BA), the Global Fire Emissions Database (GFED, 1997 2010) and Monitoring Trends in Burn Severity (MTBS, 1984 2009) BA products. For each US National Climate Assessment (NCA) region, we analyzed the relationships between monthly BA and potential evaporation (PE) derived from reanalysis climate data at 0.5 resolution. US fire activity increased over the past 25 yr, with statistically significant increases in MTBS BA for entire US and the Southeast and Southwest NCA regions. Monthly PE was strongly correlated with US fire activity, yet the climate driver of PE varied regionally. Fire season temperature and shortwave radiation were the primary controls on PE and fire activity in the Alaska, while water deficit (precipitation PE) was strongly correlated with fire activity in the Plains regions and Northwest US. BA and precipitation anomalies were negatively correlated in all regions, although fuel-limited ecosystems in the Southern Plains and Southwest exhibited positive correlations with longer lead times (6 12 months). Fire season PE in creased from the 1980s 2000s, enhancing climate-driven fire risk in the southern and western US where PE-BA correlations were strongest. Spatial and temporal patterns of increasing fire season PE and BA during the 1990s 2000s highlight the potential sensitivity of US fire activity to climate change in coming decades. However, climatefire relationships at the national scale are complex, based on the diversity of fire types, ecosystems, and ignition sources within each NCA region. Changes in the seasonality or magnitude of climate anomalies are therefore unlikely to result in uniform changes in US fire activity.

Influence of daily versus monthly fire emissions on atmospheric model applications in the tropics

NASA Astrophysics Data System (ADS)

Marlier, M. E.; Voulgarakis, A.; Faluvegi, G.; Shindell, D. T.; DeFries, R. S.

2012-12-01

Fires are widely used throughout the tropics to create and maintain areas for agriculture, but are also significant contributors to atmospheric trace gas and aerosol concentrations. However, the timing and magnitude of fire activity can vary strongly by year and ecosystem type. For example, frequent, low intensity fires dominate in African savannas whereas Southeast Asian peatland forests are susceptible to huge pulses of emissions during regional El Niño droughts. Despite the potential implications for modeling interactions with atmospheric chemistry and transport, fire emissions have commonly been input into global models at a monthly resolution. Recognizing the uncertainty that this can introduce, several datasets have parsed fire emissions to daily and sub-daily scales with satellite active fire detections. In this study, we explore differences between utilizing the monthly and daily Global Fire Emissions Database version 3 (GFED3) products as inputs into the NASA GISS-E2 composition climate model. We aim to understand how the choice of the temporal resolution of fire emissions affects uncertainty with respect to several common applications of global models: atmospheric chemistry, air quality, and climate. Focusing our analysis on tropical ozone, carbon monoxide, and aerosols, we compare modeled concentrations with available ground and satellite observations. We find that increasing the temporal frequency of fire emissions from monthly to daily can improve correlations with observations, predominately in areas or during seasons more heavily affected by fires. Differences between the two datasets are more evident with public health applications: daily resolution fire emissions increases the number of days exceeding World Health Organization air quality targets.

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

NASA Astrophysics Data System (ADS)

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 probability. The output of the model includes biomass estimates for 44 tree species that occur in the RFE, grouped by genus. We compared the model outputs with land cover classifications derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) data and LIDAR-based estimates of biomass across the entire region, and Russian forest inventory records at selected sites. Overall, we find that the FAREAST estimates of forest biomass and general composition are consistent with the observed distribution of forest types.

Aboveground carbon sequestration in dry temperate forests varies with climate not fire regime.

PubMed

Gordon, Christopher E; Bendall, Eli R; Stares, Mitchell G; Collins, Luke; Bradstock, Ross A

2018-06-01

The storage of carbon in plant tissues and debris has been proposed as a method to offset anthropogenic increases in atmospheric [CO 2 ]. Temperate forests represent significant above-ground carbon (AGC) "sinks" because their relatively fast growth and slow decay rates optimise carbon assimilation. Fire is a common disturbance event in temperate forests globally that should strongly influence AGC because: discrete fires consume above-ground biomass releasing carbon to the atmosphere, and the long-term application of different fire-regimes select for specific plant communities that sequester carbon at different rates. We investigated the latter process by quantifying AGC storage at 104 sites in the Sydney Basin Bioregion, Australia, relative to differences in components of the fire regime: frequency, severity and interfire interval. To predict the potential impacts of future climate change on fire/AGC interactions, we stratified our field sites across gradients of mean annual temperature and precipitation and quantified within- and between-factor interactions between the fire and climate variables. In agreement with previous studies, large trees were the primary AGC sink, accounting for ~70% of carbon at sites. Generalised additive models showed that mean annual temperature was the strongest predictor of AGC storage, with a 54% near-linear decrease predicted across the 6.1°C temperature range experienced at sites. Mean annual precipitation, fire frequency, fire severity and interfire interval were consistently poor predictors of total above-ground storage, although there were some significant relationships with component stocks. Our results show resilience of AGC to frequent and severe wildfire and suggest temperature mediated decreases in forest carbon storage under future climate change predictions. © 2018 John Wiley & Sons Ltd.

Assessing landscape scale wildfire exposure for highly valued resources in a Mediterranean area.

PubMed

Alcasena, Fermín J; Salis, Michele; Ager, Alan A; Arca, Bachisio; Molina, Domingo; Spano, Donatella

2015-05-01

We used a fire simulation modeling approach to assess landscape scale wildfire exposure for highly valued resources and assets (HVR) on a fire-prone area of 680 km(2) located in central Sardinia, Italy. The study area was affected by several wildfires in the last half century: some large and intense fire events threatened wildland urban interfaces as well as other socioeconomic and cultural values. Historical wildfire and weather data were used to inform wildfire simulations, which were based on the minimum travel time algorithm as implemented in FlamMap. We simulated 90,000 fires that replicated recent large fire events in the area spreading under severe weather conditions to generate detailed maps of wildfire likelihood and intensity. Then, we linked fire modeling outputs to a geospatial risk assessment framework focusing on buffer areas around HVR. The results highlighted a large variation in burn probability and fire intensity in the vicinity of HVRs, and allowed us to identify the areas most exposed to wildfires and thus to a higher potential damage. Fire intensity in the HVR buffers was mainly related to fuel types, while wind direction, topographic features, and historically based ignition pattern were the key factors affecting fire likelihood. The methodology presented in this work can have numerous applications, in the study area and elsewhere, particularly to address and inform fire risk management, landscape planning and people safety on the vicinity of HVRs.

Landscape-scale effects of fire severity on mixed-conifer and red fir forest structure in Yosemite National Park

USGS Publications Warehouse

Kane, Van R.; Lutz, James A.; Roberts, Susan L.; Smith, Douglas F.; McGaughey, Robert J.; Povak, Nicholas A.; Brooks, Matthew L.

2013-01-01

While fire shapes the structure of forests and acts as a keystone process, the details of how fire modifies forest structure have been difficult to evaluate because of the complexity of interactions between fires and forests. We studied this relationship across 69.2 km2 of Yosemite National Park, USA, that was subject to 32 fires ⩾40 ha between 1984 and 2010. Forests types included ponderosa pine (Pinus ponderosa), white fir-sugar pine (Abies concolor/Pinus lambertiana), and red fir (Abies magnifica). We estimated and stratified burned area by fire severity using the Landsat-derived Relativized differenced Normalized Burn Ratio (RdNBR). Airborne LiDAR data, acquired in July 2010, measured the vertical and horizontal structure of canopy material and landscape patterning of canopy patches and gaps. Increasing fire severity changed structure at the scale of fire severity patches, the arrangement of canopy patches and gaps within fire severity patches, and vertically within tree clumps. Each forest type showed an individual trajectory of structural change with increasing fire severity. As a result, the relationship between estimates of fire severity such as RdNBR and actual changes appears to vary among forest types. We found three arrangements of canopy patches and gaps associated with different fire severities: canopy-gap arrangements in which gaps were enclosed in otherwise continuous canopy (typically unburned and low fire severities); patch-gap arrangements in which tree clumps and gaps alternated and neither dominated (typically moderate fire severity); and open-patch arrangements in which trees were scattered across open areas (typically high fire severity). Compared to stands outside fire perimeters, increasing fire severity generally resulted first in loss of canopy cover in lower height strata and increased number and size of gaps, then in loss of canopy cover in higher height strata, and eventually the transition to open areas with few or no trees. However, the estimated fire severities at which these transitions occurred differed for each forest type. Our work suggests that low severity fire in red fir forests and moderate severity fire in ponderosa pine and white fir-sugar pine forests would restore vertical and horizontal canopy structures believed to have been common prior to the start of widespread fire suppression in the early 1900s. The fusion of LiDAR and Landsat data identified post-fire structural conditions that would not be identified by Landsat alone, suggesting a broad applicability of combining Landsat and LiDAR data for landscape-scale structural analysis for fire management.

Fire intensity, fire severity and burn severity: A brief review and suggested usage

USGS Publications Warehouse

Keeley, J.E.

2009-01-01

Several recent papers have suggested replacing the terminology of fire intensity and fire severity. Part of the problem with fire intensity is that it is sometimes used incorrectly to describe fire effects, when in fact it is justifiably restricted to measures of energy output. Increasingly, the term has created confusion because some authors have restricted its usage to a single measure of energy output referred to as fireline intensity. This metric is most useful in understanding fire behavior in forests, but is too narrow to fully capture the multitude of ways fire energy affects ecosystems. Fire intensity represents the energy released during various phases of a fire, and different metrics such as reaction intensity, fireline intensity, temperature, heating duration and radiant energy are useful for different purposes. Fire severity, and the related term burn severity, have created considerable confusion because of recent changes in their usage. Some authors have justified this by contending that fire severity is defined broadly as ecosystem impacts from fire and thus is open to individual interpretation. However, empirical studies have defined fire severity operationally as the loss of or change in organic matter aboveground and belowground, although the precise metric varies with management needs. Confusion arises because fire or burn severity is sometimes defined so that it also includes ecosystem responses. Ecosystem responses include soil erosion, vegetation regeneration, restoration of community structure, faunal recolonization, and a plethora of related response variables. Although some ecosystem responses are correlated with measures of fire or burn severity, many important ecosystem processes have either not been demonstrated to be predicted by severity indices or have been shown in some vegetation types to be unrelated to severity. This is a critical issue because fire or burn severity are readily measurable parameters, both on the ground and with remote sensing, yet ecosystem responses are of most interest to resource managers.

Mapping burned areas and burn severity patterns across the Mediterranean region

NASA Astrophysics Data System (ADS)

Kalogeropoulos, Christos; Amatulli, Giuseppe; Kempeneers, Pieter; Sedano, Fernando; San Miguel-Ayanz, Jesus; Camia, Andrea

2010-05-01

The Mediterranean region is highly susceptible to wildfires. On average, about 60,000 fires take place in this region every year, burning on average half a million hectares of forests and natural vegetation. Wildfires cause environmental degradation and affect the lives of thousands of people in the region. In order to minimize the consequences of these catastrophic events, fire managers and national authorities need to have in their disposal accurate and updated spatial information concerning the size of the burned area as well as the burn severity patterns. Mapping burned areas and burn severity patterns is necessary to effectively support the decision-making process in what concerns strategic (long-term) planning with the definition of post-fire actions at European and national scales. Although a comprehensive archive of burnt areas exists at the European Forest Fire Information System, the analysis of the severity of the areas affected by forest fires in the region is not yet available. Fire severity is influenced by many variables, including fuel type, topography and meteorological conditions before and during the fire. The analysis of fire severity is essential to determine the socio-economic impact of forest fires, to assess fire impacts, and to determine the need of post-fire rehabilitation measures. Moreover, fire severity is linked to forest fire emissions and determines the rate of recovery of the vegetation after the fire. Satellite imagery can give important insights about the conditions of the live fuel moisture content and can be used to assess changes on vegetation structure and vitality after forest fires. Fire events occurred in Greece, Portugal and Spain during the fire season of 2009 were recorded and analyzed in a GIS environment. The Normalized Difference Vegetation Index (NDVI), the Enhanced Vegetation Index (EVI) and the Normalized Burn Ratio (NBR) were calculated from 8-days composites MODIS/TERRA imagery from March to October 2009. In addition, subtracting a post-fire from a pre-fire image derived index produces a measure of absolute change of the vegetation condition, like the differenced Normalized Burn Ratio index (dNBR). The aim of this study was the assessment of fire severity across diverse ecological and environmental conditions in the Mediterranean region. The specific objectives were: • The analysis of the correlation between the fire severity and local site conditions, including topography, fuel type, land use, land cover. • The analysis of the correlation between fire severity and fire danger conditions during the fire, as estimated by the European Forest Fire Information System. • Assessing the performance of several vegetation indices derived from MODIS imagery in estimating fire severity. • Assessing the permanence of the burnt signal for large fires as an estimate of fire severity.

Responses of pond-breeding amphibians to wildfire: Short-term patterns in occupancy and colonization

Treesearch

Blake R. Hossack; Paul Stephen Corn

2007-01-01

Wildland fires are expected to become more frequent and severe in many ecosystems, potentially posing a threat to many sensitive species. We evaluated the effects of a large, stand-replacement wildfire on three species of pond-breeding amphibians by estimating changes in occupancy of breeding sites during the three years before and after the fire burned 42 of 83...

Predicting post-fire hillslope erosion in forest lands of the western United States

Treesearch

Mary Ellen Miller; Lee H. MacDonald; Peter R. Robichaud; William J. Elliot

2011-01-01

Many forests and their associated water resources are at increasing risk from large and severe wildfires due to high fuel accumulations and climate change. Extensive fuel treatments are being proposed, but it is not clear where such treatments should be focussed. The goals of this project were to: (1) predict potential post-fire erosion rates for forests and shrublands...

Effects of forest fires and post-fire rehabilitation: a Colorado, USA case study

Treesearch

Lee H. MacDonald; Isaac J. Larsen

2009-01-01

Anthropogenic activities have increased the number of large, high-burn severity wildfires in the lower and mid-elevation coniferous forests in Colorado as well as much of the western US. Forests provide most of the water for cities and agriculture, and the increased runoff and erosion after wildfires is a major concern because of the potential adverse effects on...

Mapping ground cover using hyperspectral remote sensing after the 2003 Simi and Old wildfires in southern California

Treesearch

Sarah A. Lewis; Leigh B. Lentile; Andrew T. Hudak; Peter R. Robichaud; Penelope Morgan; Michael J. Bobbitt

2007-01-01

Wildfire effects on the ground surface are indicative of the potential for post-fire watershed erosion response. Areas with remaining organic ground cover will likely experience less erosion than areas of complete ground cover combustion or exposed mineral soil. The Simi and Old fires burned ~67,000 ha in southern California in 2003. Burn severity indices calculated...

Climate, lightning ignitions, and fire severity in Yosemite National Park, California, USA

USGS Publications Warehouse

Lutz, J.A.; van Wagtendonk, J.W.; Thode, A.E.; Miller, J.D.; Franklin, J.F.

2009-01-01

Continental-scale studies of western North America have attributed recent increases in annual area burned and fire size to a warming climate, but these studies have focussed on large fires and have left the issues of fire severity and ignition frequency unaddressed. Lightning ignitions, any of which could burn a large area given appropriate conditions for fire spread, could be the first indication of more frequent fire. We examined the relationship between snowpack and the ignition and size of fires that occurred in Yosemite National Park, California (area 3027 km2), between 1984 and 2005. During this period, 1870 fires burned 77 718 ha. Decreased spring snowpack exponentially increased the number of lightning-ignited fires. Snowpack mediated lightning-ignited fires by decreasing the proportion of lightning strikes that caused lightning-ignited fires and through fewer lightning strikes in years with deep snowpack. We also quantified fire severity for the 103 fires >40 ha with satellite fire-severity indices using 23 years of Landsat Thematic Mapper data. The proportion of the landscape that burned at higher severities and the complexity of higher-severity burn patches increased with the log10 of annual area burned. Using one snowpack forecast, we project that the number of lightning-ignited fires will increase 19.1% by 2020 to 2049 and the annual area burned at high severity will increase 21.9%. Climate-induced decreases in snowpack and the concomitant increase in fire severity suggest that existing assumptions may be understated-fires may become more frequent and more severe. ?? IAWF 2009.

Numerical investigation of aggregated fuel spatial pattern impacts on fire behavior

DOE PAGES

Parsons, Russell A.; Linn, Rodman Ray; Pimont, Francois; ...

2017-06-18

Here, landscape heterogeneity shapes species distributions, interactions, and fluctuations. Historically, in dry forest ecosystems, low canopy cover and heterogeneous fuel patterns often moderated disturbances like fire. Over the last century, however, increases in canopy cover and more homogeneous patterns have contributed to altered fire regimes with higher fire severity. Fire management strategies emphasize increasing within-stand heterogeneity with aggregated fuel patterns to alter potential fire behavior. Yet, little is known about how such patterns may affect fire behavior, or how sensitive fire behavior changes from fuel patterns are to winds and canopy cover. Here, we used a physics-based fire behavior model,more » FIRETEC, to explore the impacts of spatially aggregated fuel patterns on the mean and variability of stand-level fire behavior, and to test sensitivity of these effects to wind and canopy cover. Qualitative and quantitative approaches suggest that spatial fuel patterns can significantly affect fire behavior. Based on our results we propose three hypotheses: (1) aggregated spatial fuel patterns primarily affect fire behavior by increasing variability; (2) this variability should increase with spatial scale of aggregation; and (3) fire behavior sensitivity to spatial pattern effects should be more pronounced under moderate wind and fuel conditions.« less

Numerical investigation of aggregated fuel spatial pattern impacts on fire behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parsons, Russell A.; Linn, Rodman Ray; Pimont, Francois

Here, landscape heterogeneity shapes species distributions, interactions, and fluctuations. Historically, in dry forest ecosystems, low canopy cover and heterogeneous fuel patterns often moderated disturbances like fire. Over the last century, however, increases in canopy cover and more homogeneous patterns have contributed to altered fire regimes with higher fire severity. Fire management strategies emphasize increasing within-stand heterogeneity with aggregated fuel patterns to alter potential fire behavior. Yet, little is known about how such patterns may affect fire behavior, or how sensitive fire behavior changes from fuel patterns are to winds and canopy cover. Here, we used a physics-based fire behavior model,more » FIRETEC, to explore the impacts of spatially aggregated fuel patterns on the mean and variability of stand-level fire behavior, and to test sensitivity of these effects to wind and canopy cover. Qualitative and quantitative approaches suggest that spatial fuel patterns can significantly affect fire behavior. Based on our results we propose three hypotheses: (1) aggregated spatial fuel patterns primarily affect fire behavior by increasing variability; (2) this variability should increase with spatial scale of aggregation; and (3) fire behavior sensitivity to spatial pattern effects should be more pronounced under moderate wind and fuel conditions.« less

Meta-analysis of avian and small-mammal response to fire severity and fire surrogate treatments in U.S. fire-prone forests.

PubMed

Fontaine, Joseph B; Kennedy, Patricia L

2012-07-01

Management in fire-prone ecosystems relies widely upon application of prescribed fire and/or fire surrogate (e.g., forest thinning) treatments to maintain biodiversity and ecosystem function. Recently, published literature examining wildlife response to fire and fire management has increased rapidly. However, none of this literature has been synthesized quantitatively, precluding assessment of consistent patterns of wildlife response among treatment types. Using meta-analysis, we examined the scientific literature on vertebrate demographic responses to burn severity (low/moderate, high), fire surrogates (forest thinning), and fire and fire surrogate combined treatments in the most extensively studied fire-prone, forested biome (forests of the United States). Effect sizes (magnitude of response) and their 95% confidence limits (response consistency) were estimated for each species-by-treatment combination with two or more observations. We found 41 studies of 119 bird and 17 small-mammal species that examined short-term responses (< or =4 years) to thinning, low/moderate- and high-severity fire, and thinning plus prescribed fire; data on other taxa and at longer time scales were too sparse to permit quantitative assessment. At the stand scale (<50 ha), thinning and low/moderate-severity fire demonstrated similar response patterns in these forests. Combined thinning plus prescribed fire produced a higher percentage of positive responses. High-severity fire provoked stronger responses, with a majority of species possessing higher or lower effect sizes relative to fires of lower severity. In the short term and at fine spatial scales, fire surrogate forest-thinning treatments appear to effectively mimic low/moderate-severity fire, whereas low/moderate-severity fire is not a substitute for high-severity fire. The varied response of taxa to each of the four conditions considered makes it clear that the full range of fire-based disturbances (or their surrogates) is necessary to maintain a full complement of vertebrate species, including fire-sensitive taxa. This is especially true for high-severity fire, where positive responses from many avian taxa suggest that this disturbance (either as wildfire or prescribed fire) should be included in management plans where it is consistent with historic fire regimes and where maintenance of regional vertebrate biodiversity is a goal.

Linking tree demography to climate change feedbacks: fire, larch forests, and carbon pools of the Siberian Arctic

NASA Astrophysics Data System (ADS)

Alexander, H. D.; Loranty, M. M.; Natali, S.; Pena, H., III; Ludwig, S.; Spektor, V.; Davydov, S. P.; Zimov, N.; Mack, M. C.

2017-12-01

Fire severity is increasing in larch forests of the Siberian Arctic as climate warms, and initial fire impacts on tree demographic processes could be an especially important determinant of long-term forest structure and carbon (C) dynamics. We hypothesized that (1) larch forest regrowth post-fire is largely determined by residual soil organic layer (SOL) depth because of the SOL's role as a seedbed and thermal regulator, and (2) changes in post-fire larch recruitment impact C accumulation through stand density impacts on understory microclimate and permafrost thaw. We tested these hypotheses by (1) experimentally creating a soil burn severity gradient in a Cajander larch (Larix cajanderi Mayr.) forest near Cherskiy, Russia and (2) quantifying C pools across a stand density gradient within a 75-year old fire scar. From 2012-2015, we added larch seeds to plots burned at different severities and monitored recruitment along with permafrost and active layer (i.e., subject to annual freeze-thaw) conditions (SOL depth, temperature, moisture, and thaw depth). Across the density gradient, we inventoried larch trees and harvested ground-layer vegetation to estimate aboveground contribution to C pools. We quantified woody debris C pools and sampled belowground C pools (soil, fine roots, and coarse roots) in the organic + upper (0-10 cm) mineral soil. Larch recruits were rare in unburned and low severity plots, but a total of 6 new germinants m-2 were tallied in moderate and high severity plots during the study. Seedling survival for > 1 year was only 40 and 25% on moderate and high severity treatments, respectively, but yielded net larch recruitment of 2 seedlings m-2, compared to 0.3 seedlings m-2 on low severity plots. Density of both total and established recruits increased with decreasing residual SOL depth, which correlated with increased soil temperature, moisture, and thaw depth. At 75-year post-fire, total C pools increased with increased larch density, largely due to increased tree aboveground C pools and decreased ground-layer vegetation C pools, which corresponded to higher canopy cover, cooler soils, and shallower active layer depths. Our findings highlight the potential for a climate-driven increase in fire severity to alter tree recruitment, successional dynamics, and C cycling in Siberian larch forests.

A transdisciplinary approach to understanding the health effects of wildfire and prescribed fire smoke regimes

NASA Astrophysics Data System (ADS)

Williamson, G. J.; Bowman, D. M. J. S.; Price, O. F.; Henderson, S. B.; Johnston, F. H.

2016-12-01

Prescribed burning is used to reduce the occurrence, extent and severity of uncontrolled fires in many flammable landscapes. However, epidemiologic evidence of the human health impacts of landscape fire smoke emissions is shaping fire management practice through increasingly stringent environmental regulation and public health policy. An unresolved question, critical for sustainable fire management, concerns the comparative human health effects of smoke from wild and prescribed fires. Here we review current knowledge of the health effects of landscape fire emissions and consider the similarities and differences in smoke from wild and prescribed fires with respect to the typical combustion conditions and fuel properties, the quality and magnitude of air pollution emissions, and the potential for dispersion to large populations. We further examine the interactions between these considerations, and how they may shape the longer term smoke regimes to which populations are exposed. We identify numerous knowledge gaps and propose a conceptual framework that describes pathways to better understanding of the health trade-offs of prescribed and wildfire smoke regimes.

Burn me twice, shame on who? Interactions between successive forest fires across a temperate mountain region.

PubMed

Harvey, Brian J; Donato, Daniel C; Turner, Monica G

2016-09-01

Increasing rates of natural disturbances under a warming climate raise important questions about how multiple disturbances interact. Escalating wildfire activity in recent decades has resulted in some forests re-burning in short succession, but how the severity of one wildfire affects that of a subsequent wildfire is not fully understood. We used a field-validated, satellite-derived, burn-severity atlas to assess interactions between successive wildfires across the US Northern Rocky Mountains a 300,000-km 2 region dominated by fire-prone forests. In areas that experienced two wildfires between 1984 and 2010, we asked: (1) How do overall frequency distributions of burn-severity classes compare between first and second fires? (2) In a given location, how does burn severity of the second fire relate to that of the first? (3) Do interactions between successive fires vary by forest zone or the interval between fires? (4) What factors increase the probability of burning twice as stand-replacing fire? Within the study area, 138,061 ha burned twice between 1984 and 2010. Overall, frequency distributions of burn severity classes (low, moderate, high; quantified using relativized remote sensing indices) were similar between the first and second fires; however burn severity was 5-13% lower in second fires on average. Negative interactions between fires were most pronounced in lower-elevation forests and woodlands, when fire intervals were <10 yr, and when burn severity was low in the first fire. When the first fire burned as high severity and fire intervals exceeded 10-12 yr, burn-severity interactions switched from negative to positive, with high-severity fire begetting subsequent high-severity fire. Locations most likely to experience successive stand-replacing fires were high-elevation forests, which are adapted to high-severity fire, and areas conducive to abundant post-fire tree regeneration. Broadly similar severities among short-interval "re-burns" and other wildfires indicate that positive severity feedbacks, an oft-posited agent of ecosystem decline or state shift, are not an inevitable outcome of re-burning. Nonetheless, context-dependent shifts in both the magnitude and direction of wildfire interactions (associated with forest zone, initial burn-severity, and disturbance interval) illustrate complexities in disturbance interactions and can inform management and predictions of future system dynamics. © 2016 by the Ecological Society of America.

Are High-Severity Fires Burning at Much Higher Rates Recently than Historically in Dry-Forest Landscapes of the Western USA?

PubMed

Baker, William L

2015-01-01

Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use effects. Their setting is fire-prone, they have been altered by land-uses, and fire severity may be increasing. However, where fires were excluded, increased fire could also be hypothesized as restorative of historical fire. These competing hypotheses are not well tested, as reference data prior to widespread land-use expansion were insufficient. Moreover, fire-climate projections were lacking for these forests. Here, I used new reference data and records of high-severity fire from 1984-2012 across all dry forests (25.5 million ha) of the western USA to test these hypotheses. I also approximated projected effects of climatic change on high-severity fire in dry forests by applying existing projections. This analysis showed the rate of recent high-severity fire in dry forests is within the range of historical rates, or is too low, overall across dry forests and individually in 42 of 43 analysis regions. Significant upward trends were lacking overall from 1984-2012 for area burned and fraction burned at high severity. Upward trends in area burned at high severity were found in only 4 of 43 analysis regions. Projections for A.D. 2046-2065 showed high-severity fire would generally be still operating at, or have been restored to historical rates, although high projections suggest high-severity fire rotations that are too short could ensue in 6 of 43 regions. Programs to generally reduce fire severity in dry forests are not supported and have significant adverse ecological impacts, including reducing habitat for native species dependent on early-successional burned patches and decreasing landscape heterogeneity that confers resilience to climatic change. Some adverse ecological effects of high-severity fires are concerns. Managers and communities can improve our ability to live with high-severity fire in dry forests.

Pyrodiversity promotes avian diversity over the decade following forest fire.

PubMed

Tingley, Morgan W; Ruiz-Gutiérrez, Viviana; Wilkerson, Robert L; Howell, Christine A; Siegel, Rodney B

2016-10-12

An emerging hypothesis in fire ecology is that pyrodiversity increases species diversity. We test whether pyrodiversity-defined as the standard deviation of fire severity-increases avian biodiversity at two spatial scales, and whether and how this relationship may change in the decade following fire. We use a dynamic Bayesian community model applied to a multi-year dataset of bird surveys at 1106 points sampled across 97 fires in montane California. Our results provide strong support for a positive relationship between pyrodiversity and bird diversity. This relationship interacts with time since fire, with pyrodiversity having a greater effect on biodiversity at 10 years post-fire than at 1 year post-fire. Immediately after fires, patches of differing burn severities hold similar bird communities, but over the ensuing decade, bird assemblages within patches of contrasting severities differentiate. When evaluated at the scale of individual fires, fires with a greater heterogeneity of burn severities hold substantially more species. High spatial heterogeneity in severity, sometimes called 'mixed-severity fire', is a natural part of wildfire regimes in western North America, but may be jeopardized by climate change and a legacy of fire suppression. Forest management that encourages mixed-severity fire may be critical for sustaining biodiversity across fire-prone landscapes. © 2016 The Author(s).

Fire severity estimated from remote sensing data to evaluate the Coupled Atmosphere-Wildland Fire-Environment (CAWFE) model

NASA Astrophysics Data System (ADS)

Oliva, P.; Coen, J.; Schroeder, W.

2013-12-01

Fire severity defined as the degree of damage originated from fire on soils and vegetation immediately after the fire, is affected by weather conditions (i.e. wind, air humidity), terrain characteristics (i.e. slope, aspect) and fuel properties (i.e. tree density, fuel moisture content). In this study we evaluated the relationships between fire severity estimated from Earth Observing Advance Land Imager (EO-ALI) images and the heat fluxes produced by the Coupled Atmosphere-Wildland Fire-Environment (CAWFE) model (Coen 2013). We present the results for a large fire occurred in New Mexico in June 2012 which burned 44,330 acres. The EO-ALI sensor (30 m spatial resolution) has nine spectral bands, six of them were designed to mimic Landsat bands and the three additional bands cover 443, 867.5 and 1250 nm. We used a physically-based approach to estimate fire severity developed by De Santis et al. (2009). This method classifies the satellite image into Geophysical Composite burned index (GeoCBI) values, which represent the fire severity within the fire-affected area, using radiative transfer model simulated spectra as reference. This method has been used to characterize fire severity levels using Landsat images and validated with field data (R2 > 0.85). Based on those results we expected a better performance of EO-ALI images due to its improved spectral resolution. On the other hand, CAWFE is composed of two parts: a numerical weather prediction model and a fire behavior module that represents the growth of a wildland fire in response to factors such as wind, terrain, and fuels, and includes the fire's impact on the atmosphere. To perform the evaluation we selected a stratified random sample by fire severity level. The values of maximum heat flux (sensible, latent), and total heat flux showed a higher correlation with the higher levels of fire severity (GeoCBI: 2.8-3) than with the medium levels of fire severity (GeoCBI: 2.3-2.8). However, the total heat flux proved to have a high correlation with the fire severity estimated in terms of GeoCBI values. The GeoCBI is a semi-quantitative index that takes into account the effects on vegetation by means of evaluating several variables such as, percentage of scorched leaves, height of carbon and change in LAI. Therefore, the results obtained in this study pointed out the good performance of the CAWFE model simulating the effects of fire in vegetation. Interpreting the outputs of the CAWFE model in terms of fire severity will help fire managers and decision makers understand the effects of the fire and prioritize the areas more severely affected. Fire severity classification estimated as GeoCBI values. The GeoCBI range from 0 to 3, where 0 means not affected by fire, and 3 means very high fire severity.

Mixed-severity fire regimes in the northern Rocky Mountains: consequences of fire exclusion and options for the future

Treesearch

Stephen F. Arno; David J. Parsons; Robert E. Keane

2000-01-01

Findings from fire history studies have increasingly indicated that many forest ecosystems in the northern Rocky Mountains were shaped by mixed-severity fire regimes, characterized by fires of variable severities at intervals averaging between about 30 and 100 years. Perhaps because mixed-severity fire regimes and their resulting vegetational patterns are difficult to...

Charcoal Reflectance Reveals Early Holocene Boreal Deciduous Forests Burned at High Intensities

PubMed Central

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

2015-01-01

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

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

PubMed

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

2015-01-01

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

Improving Large-scale Biomass Burning Carbon Consumption and Emissions Estimates in the Former Soviet Union based on Fire Weather

NASA Astrophysics Data System (ADS)

Westberg, D. J.; Soja, A. J.; Tchebakova, N.; Parfenova, E. I.; Kukavskaya, E.; de Groot, B.; McRae, D.; Conard, S. G.; Stackhouse, P. W., Jr.

2012-12-01

Estimating the amount of biomass burned during fire events is challenging, particularly in remote and diverse regions, like those of the Former Soviet Union (FSU). Historically, we have typically assumed 25 tons of carbon per hectare (tC/ha) is emitted, however depending on the ecosystem and severity, biomass burning emissions can range from 2 to 75 tC/ha. Ecosystems in the FSU span from the tundra through the taiga to the forest-steppe, steppe and desserts and include the extensive West Siberian lowlands, permafrost-lain forests and agricultural lands. Excluding this landscape disparity results in inaccurate emissions estimates and incorrect assumptions in the transport of these emissions. In this work, we present emissions based on a hybrid ecosystem map and explicit estimates of fuel that consider the depth of burning based on the Canadian Forest Fire Weather Index System. Specifically, the ecosystem map is a fusion of satellite-based data, a detailed ecosystem map and Alexeyev and Birdsey carbon storage data, which is used to build carbon databases that include the forest overstory and understory, litter, peatlands and soil organic material for the FSU. We provide a range of potential carbon consumption estimates for low- to high-severity fires across the FSU that can be used with fire weather indices to more accurately estimate fire emissions. These data can be incorporated at ecoregion and administrative territory scales and are optimized for use in large-scale Chemical Transport Models. Additionally, paired with future climate scenarios and ecoregion cover, these carbon consumption data can be used to estimate potential emissions.

Inerting and atmospheres

NASA Technical Reports Server (NTRS)

Carhart, Homer W.

1987-01-01

It is argued that fires are dependent primarily on the concentration of oxygen, whereas life is dependent on the partial pressure of oxygen. It follows that in an inhabited capsule it should be possible to exercise a certain amount of willful control over fire and still maintain habitability by proper selection of the composition of the atmosphere. This leads to two concepts in the control of fires in confined spaces by controlling atmospheric composition: the first, to lower the overall potential hazard by maintaining the percent of oxygen in the capsule below that of air, and second, to provide for the emergency extinguishment of a fire by sudden flooding with nitrogen. Several relevant charts and graphs are presented.

Mid-21st-century climate changes increase predicted fire occurrence and fire season length, Northern Rocky Mountains, United States

USGS Publications Warehouse

Riley, Karin L.; Loehman, Rachel A.

2016-01-01

Climate changes are expected to increase fire frequency, fire season length, and cumulative area burned in the western United States. We focus on the potential impact of mid-21st-century climate changes on annual burn probability, fire season length, and large fire characteristics including number and size for a study area in the Northern Rocky Mountains. Although large fires are rare they account for most of the area burned in western North America, burn under extreme weather conditions, and exhibit behaviors that preclude methods of direct control. Allocation of resources, development of management plans, and assessment of fire effects on ecosystems all require an understanding of when and where fires are likely to burn, particularly under altered climate regimes that may increase large fire occurrence. We used the large fire simulation model FSim to model ignition, growth, and containment of wildfires under two climate scenarios: contemporary (based on instrumental weather) and mid-century (based on an ensemble average of global climate models driven by the A1B SRES emissions scenario). Modeled changes in fire patterns include increased annual burn probability, particularly in areas of the study region with relatively short contemporary fire return intervals; increased individual fire size and annual area burned; and fewer years without large fires. High fire danger days, represented by threshold values of Energy Release Component (ERC), are projected to increase in number, especially in spring and fall, lengthening the climatic fire season. For fire managers, ERC is an indicator of fire intensity potential and fire economics, with higher ERC thresholds often associated with larger, more expensive fires. Longer periods of elevated ERC may significantly increase the cost and complexity of fire management activities, requiring new strategies to maintain desired ecological conditions and limit fire risk. Increased fire activity (within the historical range of frequency and severity, and depending on the extent to which ecosystems are adapted) may maintain or restore ecosystem functionality; however, in areas that are highly departed from historical fire regimes or where there is disequilibrium between climate and vegetation, ecosystems may be rapidly and persistently altered by wildfires, especially those that burn under extreme conditions.

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, U.S.A.

PubMed

Fraver, Shawn; Jain, Theresa; Bradford, John B; D'Amato, Anthony W; Kastendick, Doug; Palik, Brian; Shinneman, Doug; Stanovick, John

2011-09-01

Although primarily used to mitigate economic losses following disturbance, salvage logging has also been justified on the basis of reducing fire risk and fire severity; however, its ability to achieve these secondary objectives remains unclear. The patchiness resulting from a sequence of recent disturbances-blowdown, salvage logging, and wildfire-provided an excellent opportunity to assess the impacts of blowdown and salvage logging on wildfire severity. We used two fire-severity assessments (tree-crown and forest-floor characteristics) to compare post-wildfire conditions among three treatment combinations (Blowdown-Salvage-Fire, Blowdown-Fire, and Fire only). Our results suggest that salvage logging reduced the intensity (heat released) of the subsequent fire. However, its effect on severity (impact to the system) differed between the tree crowns and forest floor: tree-crown indices suggest that salvage logging decreased fire severity (albeit with modest statistical support), while forest-floor indices suggest that salvage logging increased fire severity. We attribute the latter finding to the greater exposure of mineral soil caused by logging operations; once exposed, soils are more likely to register the damaging effects of fire, even if fire intensity is not extreme. These results highlight the important distinction between fire intensity and severity when formulating post-disturbance management prescriptions.

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, USA

USGS Publications Warehouse

Fraver, S.; Jain, T.; Bradford, J.B.; D'Amato, A.W.; Kastendick, D.; Palik, B.; Shinneman, D.; Stanovick, J.

2011-01-01

Although primarily used to mitigate economic losses following disturbance, salvage logging has also been justified on the basis of reducing fire risk and fire severity; however, its ability to achieve these secondary objectives remains unclear. The patchiness resulting from a sequence of recent disturbances-blowdown, salvage logging, and ildfire- provided an excellent opportunity to assess the impacts of blowdown and salvage logging on wildfire severity. We used two fire-severity assessments (tree-crown and forest-floor characteristics) to compare post-wildfire conditions among three treatment combinations (Blowdown-Salvage-Fire, Blowdown-Fire, and Fire only). Our results suggest that salvage logging reduced the intensity (heat released) of the subsequent fire. However, its effect on severity (impact to the system) differed between the tree crowns and forest floor: tree-crown indices suggest that salvage logging decreased fire severity (albeit with modest statistical support), while forest-floor indices suggest that salvage logging increased fire severity. We attribute the latter finding to the greater exposure of mineral soil caused by logging operations; once exposed, soils are more likely to register the damaging effects of fire, even if fire intensity is not extreme. These results highlight the important distinction between fire intensity and severity when formulating post-disturbance management prescriptions. ?? 2011 by the Ecological Society of America.

Trends and causes of severity, size, and number of fires in northwestern California, USA.

PubMed

Miller, J D; Skinner, C N; Safford, H D; Knapp, E E; Ramirez, C M

2012-01-01

Research in the last several years has indicated that fire size and frequency are on the rise in western U.S. forests. Although fire size and frequency are important, they do not necessarily scale with ecosystem effects of fire, as different ecosystems have different ecological and evolutionary relationships with fire. Our study assessed trends and patterns in fire size and frequency from 1910 to 2008 (all fires > 40 ha), and the percentage of high-severity in fires from 1987 to 2008 (all fires > 400 ha) on the four national forests of northwestern California. During 1910-2008, mean and maximum fire size and total annual area burned increased, but we found no temporal trend in the percentage of high-severity fire during 1987-2008. The time series of severity data was strongly influenced by four years with region-wide lightning events that burned huge areas at primarily low-moderate severity. Regional fire rotation reached a high of 974 years in 1984 and fell to 95 years by 2008. The percentage of high-severity fire in conifer-dominated forests was generally higher in areas dominated by smaller-diameter trees than in areas with larger-diameter trees. For Douglas-fir forests, the percentage of high-severity fire did not differ significantly between areas that re-burned and areas that only burned once (10% vs. 9%) when re-burned within 30 years. Percentage of high-severity fire decreased to 5% when intervals between first and second fires were > 30 years. In contrast, in both mixed-conifer and fir/high-elevation conifer forests, the percentage of high-severity fire was less when re-burned within 30 years compared to first-time burned (12% vs. 16% for mixed conifer; 11% vs. 19% for fir/high-elevation conifer). Additionally, the percentage of high-severity fire did not differ whether the re-burn interval was less than or greater than 30 years. Years with larger fires and greatest area burned were produced by region-wide lightning events, and characterized by less winter and spring precipitation than years dominated by smaller human-ignited fires. Overall percentage of high-severity fire was generally less in years characterized by these region-wide lightning events. Our results suggest that, under certain conditions, wildfires could be more extensively used to achieve ecological and management objectives in northwestern California.

Severe fire weather and intensive forest management increase fire severity in a multi-ownership landscape.

PubMed

Zald, Harold S J; Dunn, Christopher J

2018-04-26

Many studies have examined how fuels, topography, climate, and fire weather influence fire severity. Less is known about how different forest management practices influence fire severity in multi-owner landscapes, despite costly and controversial suppression of wildfires that do not acknowledge ownership boundaries. In 2013, the Douglas Complex burned over 19,000 ha of Oregon & California Railroad (O&C) lands in Southwestern Oregon, USA. O&C lands are composed of a checkerboard of private industrial and federal forestland (Bureau of Land Management, BLM) with contrasting management objectives, providing a unique experimental landscape to understand how different management practices influence wildfire severity. Leveraging Landsat based estimates of fire severity (Relative differenced Normalized Burn Ratio, RdNBR) and geospatial data on fire progression, weather, topography, pre-fire forest conditions, and land ownership, we asked (1) what is the relative importance of different variables driving fire severity, and (2) is intensive plantation forestry associated with higher fire severity? Using Random Forest ensemble machine learning, we found daily fire weather was the most important predictor of fire severity, followed by stand age and ownership, followed by topographic features. Estimates of pre-fire forest biomass were not an important predictor of fire severity. Adjusting for all other predictor variables in a general least squares model incorporating spatial autocorrelation, mean predicted RdNBR was higher on private industrial forests (RdNBR 521.85 ± 18.67 [mean ± SE]) vs. BLM forests (398.87 ± 18.23) with a much greater proportion of older forests. Our findings suggest intensive plantation forestry characterized by young forests and spatially homogenized fuels, rather than pre-fire biomass, were significant drivers of wildfire severity. This has implications for perceptions of wildfire risk, shared fire management responsibilities, and developing fire resilience for multiple objectives in multi-owner landscapes. © 2018 by the Ecological Society of America.

Mixed-severity fire history at a forest-grassland ecotone in west central British Columbia, Canada.

PubMed

Harvey, Jill E; Smith, Dan J; Veblen, Thomas T

2017-09-01

This study examines spatially variable stand structure and fire-climate relationships at a low elevation forest-grassland ecotone in west central British Columbia, Canada. Fire history reconstructions were based on samples from 92 fire-scarred trees and stand demography from 27 plots collected over an area of about 7 km 2 . We documented historical chronologies of widespread fires and localized grassland fires between AD 1600 and 1900. Relationships between fire events, reconstructed values of the Palmer Drought Severity Index, and annual precipitation were examined using superposed epoch and bivariate event analyses. Widespread fires occurred during warm, dry years and were preceded by multiple anomalously dry, warm years. Localized fires that affected only grassland-proximal forests were more frequent than widespread fires. These localized fires showed a lagged, positive relationship with wetter conditions. The landscape pattern of forest structure provided further evidence of complex fire activity with multiple plots shown to have experienced low-, mixed-, and/or high-severity fires over the last four centuries. We concluded that this forest-grassland ecotone was characterized by fires of mixed severity, dominated by frequent, low-severity fires punctuated by widespread fires of moderate to high severity. This landscape-level variability in fire-climate relationships and patterns in forest structure has important implications for fire and grassland management in west central British Columbia and similar environments elsewhere. Forest restoration techniques such as prescribed fire and thinning are oftentimes applied at the forest-grassland ecotone on the basis that historically high frequency, low-severity fires defined the character of past fire activity. This study provides forest managers and policy makers with important information on mixed-severity fire activity at a low elevation forest-grassland ecotone, a crucial prerequisite for the effective management of these complex ecosystems. © 2017 by the Ecological Society of America.

Monitoring post-fire changes in species composition and stand structure in boreal forests using high-resolution, 3-D aerial drone data and Landsat

NASA Astrophysics Data System (ADS)

Alonzo, M.; Morton, D. C.; Cook, B.; Andersen, H. E.; Mack, M. C.

2017-12-01

The growing frequency and severity of boreal forest fires has important consequences for fire carbon emissions and ecosystem composition. Severe fires are typically associated with high degrees of both canopy and soil organic layer (SOL) consumption, particularly in black spruce stands. Complete canopy consumption can decrease the likelihood of spruce regeneration due to reduced viability of the aerial seedbank. Deeper burning of the SOL increases fire emissions and can expose mineral soil that promotes colonization by broadleaf species. There is mounting evidence that a disturbance-driven shift from spruce to broadleaf forests may indicate an ecological state change with feedbacks to regional and global climate. If post-fire successional dynamics can be characterized at an ecosystem scale using remote sensing data, we will be better equipped to constrain carbon and energy fluxes from SOL losses and albedo changes. In this study, we used Landsat time series, very high-resolution structure-from-motion (SFM) drone imagery, and field measurements to investigate post-fire regrowth 13 years after the 2004 Taylor Complex (TC) fires in interior Alaska. Twenty-seven TC plots span a gradient of moisture conditions and burn severity as estimated by loss of SOL. A range of variables potentially governing seedling species dominance (e.g., moisture status, distance to seed sources) have been collected systematically over the years following fire. In July 2017, we additionally collected < 2 cm resolution drone imagery over 25 of the TC plots. We processed these highly overlapped, nadir-view and oblique angle photos into extremely dense (>700 pts/m2) RGB-colored point clouds using SFM techniques. With these point clouds and high resolution orthomosaics, we estimated: 1) snag heights and biomass, 2) remnant snag fine branching, and 3) species and structure of shrubs and groundcover that have regrown since fire. We additionally assembled a dense Landsat time series arranged by day-of-year to monitor pre-fire and post-fire phenology. Our preliminary results illustrate how ultra-fine and moderate-scale remote sensing can be used to better understand the processes of ecosystem regeneration following fire.

The role of climate and vegetation change in shaping past and future fire regimes in the northwestern US and the implications for ecosystem management

USGS Publications Warehouse

Whitlock, C.; Shafer, S.L.; Marlon, J.

2003-01-01

Fire is an important part of the disturbance regimes of northwestern US forests and its role in maintaining and altering forest vegetation is evident in the paleoecological record of the region. Long-term reconstructions of Holocene fire regimes, provided by the analysis of charcoal, pollen, and other fire proxies in a network of lake records, indicate that the Pacific Northwest and summer-dry regions of the northern Rocky Mountains experienced their highest fire activity in the early Holocene (11,000-7000 years ago) and during the Medieval Warm Period (ca. 1000 years ago) when drought conditions were more severe than today. In contrast, in summer-wet areas of the northern Rocky Mountains, the period of highest fire activity was registered in the last 7000 years when dry woodland vegetation developed. When synthesized across the entire northwestern US, the paleoecological record reveals that past and present fire regimes are strongly controlled by climate changes occurring on multiple time scales. The scarcity of fires in the 20th century in some northwestern US ecosystems may be the result of successful fire suppression policies, but in wetter forests this absence is consistent with long-term fire regime patterns. In addition, simulations of potential future climate and vegetation indicate that future fire conditions in some parts of the northwestern US could be more severe than they are today. The Holocene record of periods of intensified summer drought is used to assess the nature of future fire-climate-vegetation linkages in the region. ?? 2003 Elsevier Science B.V. All rights reserved.

Perceptions of Post-Wildfire Landscape Change and Recovery

NASA Astrophysics Data System (ADS)

Kooistra, C. M.; Hall, T. E.; Paveglio, T.; Carroll, M.; Smith, A. M.

2013-12-01

Considering the dynamic nature of the earth and climate systems and the increasing potential for widespread forest disturbances, it is important to understand the implications of landscape changes, and perceptions of changes, on people's responses to forest disturbances. Understanding how people perceive landscape change over time following forest disturbances helps researchers, land managers, and community leaders identify important biophysical and social characteristics that influence the vulnerability of people who experience forest disturbances, as well as their responses to those disturbances. This poster describes people's perceptions of landscape change following a significant wildfire. The lightning ignited Dahl fire burned 12 miles southeast of Roundup, MT mostly on private land in the summer of June 2012. The fire burned approximately 22,000 acres and destroyed 73 residences. We conducted interviews in the summer of 2013 with more than 40 residents, land managers, emergency personnel, and other stakeholders. While interviews covered several topics, this poster focuses on responses to questions regarding perceptions of short- and long-term landscape change after the fire, including both social and biophysical perspectives. Interviews revealed that people's understanding of the role of wildfires as a natural ecosystem process, as well as their connections with the landscape (i.e., sense of place), were important factors that influenced their perceptions of landscape change after the fire. Many respondents discussed the landscape ';recovering' to pre-fire conditions in longer-term timeframes, such as ';multiple generations.' They often referenced previous wildfires, the Hawk Creek fire (1984) and the Majeras fire (2006), by explaining how parts of the landscape affected by the Dahl fire might compare to certain areas of the previous fires. Variations in recovery expectations were often based on perceptions of the severity of the fire (especially temperature), post-fire restoration/seeding efforts, and what the landscape was ';supposed to look like.' Participants with a stronger understanding of the ecological role of fire seemed less concerned about the long-term negative impacts of the fire on the ecological and aesthetic aspects of the changed landscape. Others seemed to focus on the negative aspects, namely that the landscape would never return to ';normal' within their lifetime. Several residents (not interviewed) reportedly moved away because the changes to the landscape were so severe. Of course, most residents stayed, though many mentioned how important the trees in the landscape were to them and that areas burnt by the fire had lost something special. Many respondents also discussed a severe flood shortly after the fire, as well as continued erosion problems due largely to the fire's impacts on the soil and vegetation. These insights about perceptions of changes in the landscape from the fire, floods, and erosion, in terms of expected recovery over spatial and temporal scales will be explored in more detail. We also discuss the implications of these insights for understanding people's attitudes about wildfire management and for communicating about wildfire issues with the public.

Impact of anthropogenic climate change on wildfire across western US forests.

PubMed

Abatzoglou, John T; Williams, A Park

2016-10-18

Increased forest fire activity across the western continental United States (US) in recent decades has likely been enabled by a number of factors, including the legacy of fire suppression and human settlement, natural climate variability, and human-caused climate change. We use modeled climate projections to estimate the contribution of anthropogenic climate change to observed increases in eight fuel aridity metrics and forest fire area across the western United States. Anthropogenic increases in temperature and vapor pressure deficit significantly enhanced fuel aridity across western US forests over the past several decades and, during 2000-2015, contributed to 75% more forested area experiencing high (>1 σ) fire-season fuel aridity and an average of nine additional days per year of high fire potential. Anthropogenic climate change accounted for ∼55% of observed increases in fuel aridity from 1979 to 2015 across western US forests, highlighting both anthropogenic climate change and natural climate variability as important contributors to increased wildfire potential in recent decades. We estimate that human-caused climate change contributed to an additional 4.2 million ha of forest fire area during 1984-2015, nearly doubling the forest fire area expected in its absence. Natural climate variability will continue to alternate between modulating and compounding anthropogenic increases in fuel aridity, but anthropogenic climate change has emerged as a driver of increased forest fire activity and should continue to do so while fuels are not limiting.

Impact of anthropogenic climate change on wildfire across western US forests

NASA Astrophysics Data System (ADS)

Abatzoglou, John T.; Park Williams, A.

2016-10-01

Increased forest fire activity across the western continental United States (US) in recent decades has likely been enabled by a number of factors, including the legacy of fire suppression and human settlement, natural climate variability, and human-caused climate change. We use modeled climate projections to estimate the contribution of anthropogenic climate change to observed increases in eight fuel aridity metrics and forest fire area across the western United States. Anthropogenic increases in temperature and vapor pressure deficit significantly enhanced fuel aridity across western US forests over the past several decades and, during 2000-2015, contributed to 75% more forested area experiencing high (>1 σ) fire-season fuel aridity and an average of nine additional days per year of high fire potential. Anthropogenic climate change accounted for ˜55% of observed increases in fuel aridity from 1979 to 2015 across western US forests, highlighting both anthropogenic climate change and natural climate variability as important contributors to increased wildfire potential in recent decades. We estimate that human-caused climate change contributed to an additional 4.2 million ha of forest fire area during 1984-2015, nearly doubling the forest fire area expected in its absence. Natural climate variability will continue to alternate between modulating and compounding anthropogenic increases in fuel aridity, but anthropogenic climate change has emerged as a driver of increased forest fire activity and should continue to do so while fuels are not limiting.

Modeling of multi-strata forest fire severity using Landsat TM data

Treesearch

Q. Meng; R.K. Meentemeyer

2011-01-01

Most of fire severity studies use field measures of composite burn index (CBI) to represent forest fire severity and fit the relationships between CBI and Landsat imagery derived differenced normalized burn ratio (dNBR) to predict and map fire severity at unsampled locations. However, less attention has been paid on the multi-strata forest fire severity, which...

Rapid assessment of postfire plant invasions in coniferous forests of the western United States

USGS Publications Warehouse

Freeman, J.P.; Stohlgren, T.J.; Hunter, M.E.; Omi, Philip N.; Martinson, E.J.; Chong, G.W.; Brown, C.S.

2007-01-01

Fire is a natural part of most forest ecosystems in the western United States, but its effects on nonnative plant invasion have only recently been studied. Also, forest managers are engaging in fuel reduction projects to lessen fire severity, often without considering potential negative ecological consequences such as nonnative plant species introductions. Increased availability of light, nutrients, and bare ground have all been associated with high-severity fires and fuel treatments and are known to aid in the establishment of nonnative plant species. We use vegetation and environmental data collected after wildfires at seven sites in coniferous forests in the western United States to study responses of nonnative plants to wildfire. We compared burned vs. unburned plots and plots treated with mechanical thinning and/or prescribed burning vs. untreated plots for nonnative plant species richness and cover and used correlation analyses to infer the effect of abiotic site conditions on invasibility. Wildfire was responsible for significant increases in nonnative species richness and cover, and a significant decrease in native cover. Mechanical thinning and prescribed fire fuel treatments were associated with significant changes in plant species composition at some sites. Treatment effects across sites were minimal and inconclusive due to significant site and site x treatment interaction effects caused by variation between sites including differences in treatment and fire severities and initial conditions (e.g., nonnative species sources). We used canonical correspondence analysis (CCA) to determine what combinations of environmental variables best explained patterns of nonnative plant species richness and cover. Variables related to fire severity, soil nutrients, and elevation explained most of the variation in species composition. Nonnative species were generally associated with sites with higher fire severity, elevation, percentage of bare ground, and lower soil nutrient levels and lower canopy cover. Early assessments of postfire stand conditions can guide rapid responses to nonnative plant invasions. ?? 2007 by the Ecological Society of America.

Effects of Fire on Understory Vegetation Communities in Siberian Boreal Forests and Alaskan Tundra

NASA Astrophysics Data System (ADS)

Pena, H., III; Alexander, H. D.; Natali, S.; Loranty, M. M.; Holmes, R. M.; Mack, M. C.; Schade, J. D.; Mann, P. J.; Davydov, S. P.; Frey, B.; Zimov, N.; Jardine, L. E.

2017-12-01

Fire is an important disturbance in Arctic ecosystems that is increasing in frequency and severity as a result of climate warming. Fire alters the landscape, changes soil conditions, and influences vegetation regrowth, favoring early-successional plants and those with well-established root systems capable of surviving fire. Post-fire vegetation establishment contributes to the recovery of the soil organic layer (SOL), which insulates the soil and protects soil and permafrost carbon pools. In order to better understand successional dynamics following fire in the Arctic we assessed the short-(years) and long-(decades) term effects of fire on vegetation communities, SOL depth, and thaw depth across fire-affected sites located in two regions of the Arctic- a 76-year old fire scar in a larch forest in Siberia near Cherskiy, Russia, and a 2-year old fire scar in tundra in the Yukon-Kuskokwim Delta, Alaska. We measured species diversity, plant carbon (C) pools, SOL conditions and NDVI at both study areas. As expected, there was a decline in vegetation C pools following fire in Alaskan tundra, and as a result of higher severity fire in Siberian boreal forests. Two years following fire in Alaskan tundra, vegetation C pools decreased six-fold from 600 g C m-2 at unburned areas, to 100 g C m-2 at the 2015 burn areas. In larch forests, understory C pools were three-times lower in stands with high intensity fires (135 g C m-2) compared to those with low intensity fires (415 g C m-2), due to the absence of dwarf birch (Betula nana). Our results illustrate how fire influences vegetation at both early and later stages of succession, which can have cascading effects on SOL development and permafrost integrity, with the potential for release of large C stocks that may further exacerbate climate warming.

Evaluation of Containment Boxes as a Fire Mitigation Method in Elevated Oxygen Conditions

NASA Technical Reports Server (NTRS)

Juarez, Alfredo; Harper, Susana; Perez, Horacio

2016-01-01

NASA performed testing to evaluate the efficacy of fire containment boxes without forced ventilation. Configurational flammability testing was performed on a simulation avionics box replicating critical design features and filled with materials possessing representative flammability characteristics. This paper discusses the box's ability, under simulated end-use conditions, to inhibit the propagation of combustion to surrounding materials. Analysis was also performed to evaluate the potential for the fire containment box to serve as an overheat/ignition source to temperature sensitive equipment (such as items with lithium-ion batteries). Unrealistically severe combustion scenarios were used as a means to better understand the fire containment mechanism. These scenarios were achieved by utilizing materials/fuels not typically used in space vehicles due to flammability concerns. Oxygen depletion, during combustion within the fire containment boxes, drove self-extinguishment and proved an effective method of fire containment

Monitoring the Effects of Forest Restoration Treatments on Post-Fire Vegetation Recovery with MODIS Multitemporal Data

PubMed Central

van Leeuwen, Willem J. D.

2008-01-01

This study examines how satellite based time-series vegetation greenness data and phenological measurements can be used to monitor and quantify vegetation recovery after wildfire disturbances and examine how pre-fire fuel reduction restoration treatments impact fire severity and impact vegetation recovery trajectories. Pairs of wildfire affected sites and a nearby unburned reference site were chosen to measure the post-disturbance recovery in relation to climate variation. All site pairs were chosen in forested uplands in Arizona and were restricted to the area of the Rodeo-Chediski fire that occurred in 2002. Fuel reduction treatments were performed in 1999 and 2001. The inter-annual and seasonal vegetation dynamics before, during, and after wildfire events can be monitored using a time series of biweekly composited MODIS NDVI (Moderate Resolution Imaging Spectroradiometer - Normalized Difference Vegetation Index) data. Time series analysis methods included difference metrics, smoothing filters, and fitting functions that were applied to extract seasonal and inter-annual change and phenological metrics from the NDVI time series data from 2000 to 2007. Pre- and post-fire Landsat data were used to compute the Normalized Burn Ratio (NBR) and examine burn severity at the selected sites. The phenological metrics (pheno-metrics) included the timing and greenness (i.e. NDVI) for the start, peak and end of the growing season as well as proxy measures for the rate of green-up and senescence and the annual vegetation productivity. Pre-fire fuel reduction treatments resulted in lower fire severity, which reduced annual productivity much less than untreated areas within the Rodeo-Chediski fire perimeter. The seasonal metrics were shown to be useful for estimating the rate of post-fire disturbance recovery and the timing of phenological greenness phases. The use of satellite time series NDVI data and derived pheno-metrics show potential for tracking vegetation cover dynamics and successional changes in response to drought, wildfire disturbances, and forest restoration treatments in fire-suppressed forests. PMID:27879809

Frequent fire alters nitrogen transformations in ponderosa pine stands of the inland northwest.

PubMed

DeLuca, Thomas H; Sala, Anna

2006-10-01

Recurrent, low-severity fire in ponderosa pine (Pinus ponderosa)/interior Douglas-fir (Pseudotsuga menziesii var. glauca) forests is thought to have directly influenced nitrogen (N) cycling and availability. However, no studies to date have investigated the influence of natural fire intervals on soil processes in undisturbed forests, thereby limiting our ability to understand ecological processes and successional dynamics in this important ecosystem of the Rocky Mountain West. Here, we tested the standing hypothesis that recurrent fire in ponderosa pine/Douglas-fir forests of the Inland Northwest decreases total soil N, but increases N turnover and nutrient availability. We compared soils in stands unburned over the past 69-130 years vs. stands exposed to two or more fires over the last 130 years at seven distinct locations in two wilderness areas. Mineral soil samples were collected from each of the seven sites in June and July of 2003 and analyzed for pH, total C and N, potentially mineralizable N (PMN), and extractable NH4+, NO3-, PO4(-3), Ca+2, Mg+2, and K+. Nitrogen transformations were assessed at five sites by installing ionic resin capsules in the mineral soil in August of 2003 and by conducting laboratory assays of nitrification potential and net nitrification in aerobic incubations. Total N and PMN decreased in stands subjected to multiple fires. This loss of total N and labile N was not reflected in concentrations of extractable NH4+ and NO3-. Rather, multiple fires caused an increase in NO3 sorbed on ionic resins, nitrification potential, and net nitrification in spite of the burned stands not having been exposed to fire for at least 12-17 years. Charcoal collected from a recent fire site and added to unburned soils increased nitrification potential, suggesting that the decrease of charcoal in the absence of fire may play an important role in N transformations in fire-dependent ecosystems in the long term. Interestingly, we found no consistent effect of fire frequency on extractable P or alkaline metal concentrations. Our results corroborate the largely untested hypothesis that frequent fire in ponderosa pine forests increases inorganic N availability in the long term and emphasize the need to study natural, unmanaged sites in far greater detail.

Return on investment from fuel treatments to reduce severe wildfire and erosion in a watershed investment program in Colorado.

PubMed

Jones, Kelly W; Cannon, Jeffery B; Saavedra, Freddy A; Kampf, Stephanie K; Addington, Robert N; Cheng, Antony S; MacDonald, Lee H; Wilson, Codie; Wolk, Brett

2017-08-01

A small but growing number of watershed investment programs in the western United States focus on wildfire risk reduction to municipal water supplies. This paper used return on investment (ROI) analysis to quantify how the amounts and placement of fuel treatment interventions would reduce sediment loading to the Strontia Springs Reservoir in the Upper South Platte River watershed southwest of Denver, Colorado following an extreme fire event. We simulated various extents of fuel mitigation activities under two placement strategies: (a) a strategic treatment prioritization map and (b) accessibility. Potential fire behavior was modeled under each extent and scenario to determine the impact on fire severity, and this was used to estimate expected change in post-fire erosion due to treatments. We found a positive ROI after large storm events when fire mitigation treatments were placed in priority areas with diminishing marginal returns after treating >50-80% of the forested area. While our ROI results should not be used prescriptively they do show that, conditional on severe fire occurrence and precipitation, investments in the Upper South Platte could feasibly lead to positive financial returns based on the reduced costs of dredging sediment from the reservoir. While our analysis showed positive ROI focusing only on post-fire erosion mitigation, it is important to consider multiple benefits in future ROI calculations and increase monitoring and evaluation of these benefits of wildfire fuel reduction investments for different site conditions and climates. Copyright © 2017 Elsevier Ltd. All rights reserved.

Predicting fire severity using surface fuels and moisture

Treesearch

Pamela G. Sikkink; Robert E. Keane

2012-01-01

Fire severity classifications have been used extensively in fire management over the last 30 years to describe specific environmental or ecological impacts of fire on fuels, vegetation, wildlife, and soils in recently burned areas. New fire severity classifications need to be more objective, predictive, and ultimately more useful to fire management and planning. Our...

Pyrodiversity promotes avian diversity over the decade following forest fire

PubMed Central

Ruiz-Gutiérrez, Viviana; Wilkerson, Robert L.; Howell, Christine A.; Siegel, Rodney B.

2016-01-01

An emerging hypothesis in fire ecology is that pyrodiversity increases species diversity. We test whether pyrodiversity—defined as the standard deviation of fire severity—increases avian biodiversity at two spatial scales, and whether and how this relationship may change in the decade following fire. We use a dynamic Bayesian community model applied to a multi-year dataset of bird surveys at 1106 points sampled across 97 fires in montane California. Our results provide strong support for a positive relationship between pyrodiversity and bird diversity. This relationship interacts with time since fire, with pyrodiversity having a greater effect on biodiversity at 10 years post-fire than at 1 year post-fire. Immediately after fires, patches of differing burn severities hold similar bird communities, but over the ensuing decade, bird assemblages within patches of contrasting severities differentiate. When evaluated at the scale of individual fires, fires with a greater heterogeneity of burn severities hold substantially more species. High spatial heterogeneity in severity, sometimes called ‘mixed-severity fire', is a natural part of wildfire regimes in western North America, but may be jeopardized by climate change and a legacy of fire suppression. Forest management that encourages mixed-severity fire may be critical for sustaining biodiversity across fire-prone landscapes. PMID:27708152

Emissions from an automobile fire.

PubMed

Lönnermark, Anders; Blomqvist, Per

2006-02-01

The emissions from automobile fires have been investigated. The main gas phase components were analysed in small-scale tests with representative material from an automobile. A more detailed investigation of full-scale simulated automobile fires was also conducted, including the characterisation of gas phase components, particulates and run-off water from extinguishing activities. Three separate full scale fire tests have been characterised: a fire ignited and developed in the engine compartment; a fire ignited inside the coupé, that was extinguished in the early stages; and a similar fire ignited inside the coupé that was allowed to spread until the entire vehicle was involved in the fire. The quantitative analysis of the smoke gases from the full-scale fires showed that emissions with a potentially negative impact on the environment, or chronic toxic effect on humans, were produced in significant quantities. These emissions included HCl, SO2, VOCs (e.g. benzene), PAHs, and PCDDs/PCDFs. Analysis of run-off water indicated that it was severely contaminated, containing elevated levels of both organic compounds and metals. Comparison with data from other vehicle fires found in the literature shows that contamination by lead, copper, zinc, and antimony appears to be significant in water run-off from these types of fires.

Global Pyrogeography: the Current and Future Distribution of Wildfire

PubMed Central

Krawchuk, Meg A.; Moritz, Max A.; Parisien, Marc-André; Van Dorn, Jeff; Hayhoe, Katharine

2009-01-01

Climate change is expected to alter the geographic distribution of wildfire, a complex abiotic process that responds to a variety of spatial and environmental gradients. How future climate change may alter global wildfire activity, however, is still largely unknown. As a first step to quantifying potential change in global wildfire, we present a multivariate quantification of environmental drivers for the observed, current distribution of vegetation fires using statistical models of the relationship between fire activity and resources to burn, climate conditions, human influence, and lightning flash rates at a coarse spatiotemporal resolution (100 km, over one decade). We then demonstrate how these statistical models can be used to project future changes in global fire patterns, highlighting regional hotspots of change in fire probabilities under future climate conditions as simulated by a global climate model. Based on current conditions, our results illustrate how the availability of resources to burn and climate conditions conducive to combustion jointly determine why some parts of the world are fire-prone and others are fire-free. In contrast to any expectation that global warming should necessarily result in more fire, we find that regional increases in fire probabilities may be counter-balanced by decreases at other locations, due to the interplay of temperature and precipitation variables. Despite this net balance, our models predict substantial invasion and retreat of fire across large portions of the globe. These changes could have important effects on terrestrial ecosystems since alteration in fire activity may occur quite rapidly, generating ever more complex environmental challenges for species dispersing and adjusting to new climate conditions. Our findings highlight the potential for widespread impacts of climate change on wildfire, suggesting severely altered fire regimes and the need for more explicit inclusion of fire in research on global vegetation-climate change dynamics and conservation planning. PMID:19352494

Are High-Severity Fires Burning at Much Higher Rates Recently than Historically in Dry-Forest Landscapes of the Western USA?

PubMed Central

Baker, William L.

2015-01-01

Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use effects. Their setting is fire-prone, they have been altered by land-uses, and fire severity may be increasing. However, where fires were excluded, increased fire could also be hypothesized as restorative of historical fire. These competing hypotheses are not well tested, as reference data prior to widespread land-use expansion were insufficient. Moreover, fire-climate projections were lacking for these forests. Here, I used new reference data and records of high-severity fire from 1984–2012 across all dry forests (25.5 million ha) of the western USA to test these hypotheses. I also approximated projected effects of climatic change on high-severity fire in dry forests by applying existing projections. This analysis showed the rate of recent high-severity fire in dry forests is within the range of historical rates, or is too low, overall across dry forests and individually in 42 of 43 analysis regions. Significant upward trends were lacking overall from 1984–2012 for area burned and fraction burned at high severity. Upward trends in area burned at high severity were found in only 4 of 43 analysis regions. Projections for A.D. 2046–2065 showed high-severity fire would generally be still operating at, or have been restored to historical rates, although high projections suggest high-severity fire rotations that are too short could ensue in 6 of 43 regions. Programs to generally reduce fire severity in dry forests are not supported and have significant adverse ecological impacts, including reducing habitat for native species dependent on early-successional burned patches and decreasing landscape heterogeneity that confers resilience to climatic change. Some adverse ecological effects of high-severity fires are concerns. Managers and communities can improve our ability to live with high-severity fire in dry forests. PMID:26351850

Modeling carbon-nutrient interactions during the early recovery of tundra after fire.

PubMed

Jiang, Yueyang; Rastetter, Edward B; Rocha, Adrian V; Pearce, Andrea R; Kwiatkowski, Bonnie L; Shaver, Gaius R

2015-09-01

Fire frequency has dramatically increased in the tundra of northern Alaska, USA, which has major implications for the carbon budget of the region and the functioning of these ecosystems, which support important wildlife species. We investigated the postfire succession of plant and soil carbon (C), nitrogen (N), and phosphorus (P) fluxes and stocks along a burn severity gradient in the 2007 Anaktuvuk River fire scar in northern Alaska. Modeling results indicated that the early regrowth of postfire tundra vegetation was limited primarily by its canopy photosynthetic potential, rather than nutrient availability, because of the initially low leaf area and relatively high inorganic N and P concentrations in soil. Our simulations indicated that the postfire recovery of tundra vegetation was sustained predominantly by the uptake of residual inorganic N (i.e., in the remaining ash), and the redistribution of N and P from soil organic matter to vegetation. Although residual nutrients in ash were higher in the severe burn than the moderate burn, the moderate burn recovered faster because of the higher remaining biomass and consequent photosynthetic potential. Residual nutrients in ash allowed both burn sites to recover and exceed the unburned site in both aboveground biomass and production five years after the fire. The investigation of interactions among postfire C, N, and P cycles has contributed to a mechanistic understanding of the response of tundra ecosystems to fire disturbance. Our study provided insight on how the trajectory of recovery of tundra from wildfire is regulated during early succession.

Population and Individual Elephant Response to a Catastrophic Fire in Pilanesberg National Park

PubMed Central

Woolley, Leigh-Ann; Millspaugh, Joshua J.; Woods, Rami J.; Janse van Rensburg, Samantha; Mackey, Robin L.; Page, Bruce; Slotow, Rob

2008-01-01

In predator-free large herbivore populations, where density-dependent feedbacks occur at the limit where forage resources can no longer support the population, environmental catastrophes may play a significant role in population regulation. The potential role of fire as a stochastic mass-mortality event limiting these populations is poorly understood, so too the behavioural and physiological responses of the affected animals to this type of large disturbance event. During September 2005, a wildfire resulted in mortality of 29 (18% population mortality) and injury to 18, African elephants in Pilanesberg National Park, South Africa. We examined movement and herd association patterns of six GPS-collared breeding herds, and evaluated population physiological response through faecal glucocorticoid metabolite (stress) levels. We investigated population size, structure and projected growth rates using a simulation model. After an initial flight response post-fire, severely injured breeding herds reduced daily displacement with increased daily variability, reduced home range size, spent more time in non-tourist areas and associated less with other herds. Uninjured, or less severely injured, breeding herds also shifted into non-tourist areas post-fire, but in contrast, increased displacement rate (both mean and variability), did not adjust home range size and formed larger herds post-fire. Adult cow stress hormone levels increased significantly post-fire, whereas juvenile and adult bull stress levels did not change significantly. Most mortality occurred to the juvenile age class causing a change in post-fire population age structure. Projected population growth rate remained unchanged at 6.5% p.a., and at current fecundity levels, the population would reach its previous level three to four years post-fire. The natural mortality patterns seen in elephant populations during stochastic events, such as droughts, follows that of the classic mortality pattern seen in predator-free large ungulate populations, i.e. mainly involving juveniles. Fire therefore functions in a similar manner to other environmental catastrophes and may be a natural mechanism contributing to population limitation. Welfare concerns of arson fires, burning during “hot-fire” conditions and the conservation implications of fire suppression (i.e. removal of a potential contributing factor to natural population regulation) should be integrated into fire management strategies for conservation areas. PMID:18797503

Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure

PubMed Central

Miquelajauregui, Yosune; Cumming, Steven G.; Gauthier, Sylvie

2016-01-01

It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity. PMID:26919456

Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure.

PubMed

Miquelajauregui, Yosune; Cumming, Steven G; Gauthier, Sylvie

2016-01-01

It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity.

Determining relative contributions of vegetation and topography to burn severity from LANDSAT imagery.

PubMed

Wu, Zhiwei; He, Hong S; Liang, Yu; Cai, Longyan; Lewis, Bernard J

2013-10-01

Fire is a dominant process in boreal forest landscapes and creates a spatial patch mosaic with different burn severities and age classes. Quantifying effects of vegetation and topography on burn severity provides a scientific basis on which forest fire management plans are developed to reduce catastrophic fires. However, the relative contribution of vegetation and topography to burn severity is highly debated especially under extreme weather conditions. In this study, we hypothesized that relationships of vegetation and topography to burn severity vary with fire size. We examined this hypothesis in a boreal forest landscape of northeastern China by computing the burn severity of 24 fire patches as the difference between the pre- and post-fire Normalized Difference Vegetation Index obtained from two Landsat TM images. The vegetation and topography to burn severity relationships were evaluated at three fire-size levels of small (<100 ha, n = 12), moderate (100-1,000 ha, n = 9), and large (>1,000 ha, n = 3). Our results showed that vegetation and topography to burn severity relationships were fire-size-dependent. The burn severity of small fires was primary controlled by vegetation conditions (e.g., understory cover), and the burn severity of large fires was strongly influenced by topographic conditions (e.g., elevation). For moderate fires, the relationships were complex and indistinguishable. Our results also indicated that the pattern trends of relative importance for both vegetation and topography factors were not dependent on fire size. Our study can help managers to design fire management plans according to vegetation characteristics that are found important in controlling burn severity and prioritize management locations based on the relative importance of vegetation and topography.

Determining Relative Contributions of Vegetation and Topography to Burn Severity from LANDSAT Imagery

NASA Astrophysics Data System (ADS)

Wu, Zhiwei; He, Hong S.; Liang, Yu; Cai, Longyan; Lewis, Bernard J.

2013-10-01

Fire is a dominant process in boreal forest landscapes and creates a spatial patch mosaic with different burn severities and age classes. Quantifying effects of vegetation and topography on burn severity provides a scientific basis on which forest fire management plans are developed to reduce catastrophic fires. However, the relative contribution of vegetation and topography to burn severity is highly debated especially under extreme weather conditions. In this study, we hypothesized that relationships of vegetation and topography to burn severity vary with fire size. We examined this hypothesis in a boreal forest landscape of northeastern China by computing the burn severity of 24 fire patches as the difference between the pre- and post-fire Normalized Difference Vegetation Index obtained from two Landsat TM images. The vegetation and topography to burn severity relationships were evaluated at three fire-size levels of small (<100 ha, n = 12), moderate (100-1,000 ha, n = 9), and large (>1,000 ha, n = 3). Our results showed that vegetation and topography to burn severity relationships were fire-size-dependent. The burn severity of small fires was primary controlled by vegetation conditions (e.g., understory cover), and the burn severity of large fires was strongly influenced by topographic conditions (e.g., elevation). For moderate fires, the relationships were complex and indistinguishable. Our results also indicated that the pattern trends of relative importance for both vegetation and topography factors were not dependent on fire size. Our study can help managers to design fire management plans according to vegetation characteristics that are found important in controlling burn severity and prioritize management locations based on the relative importance of vegetation and topography.

Relationship between Climate Variability, Wildfire Risk, and Wildfire Occurrence in Wildland-Urban Interface of the Southwestern United States

NASA Astrophysics Data System (ADS)

Kafatos, M.; Kim, S. H.; Jia, S.; Nghiem, S. V.

2017-12-01

As housing units in or near wildlands have grown, the wildland-urban interface (WUI) contain at present approximately one-third of all housing in the contiguous US. Wildfires are a part of the natural cycle in the Southwestern United States (SWUS) but the increasing trend of WUI has made wildfires a serious high-risk hazard. The expansion of WUI has elevated wildfire risks by increasing the chance of human caused ignitions and past fire suppression in the area. Previous studies on climate variability have shown that the SWUS region is prone to frequent droughts and has suffered from severe wildfires in the recent decade. Therefore, assessing the increased vulnerability to the wildfire in WUI is crucial for proactive adaptation under climate change. Our previous study has shown that a strong correlation between North Atlantic Oscillation (NAO) and temperature was found during March-June in the SWUS. The abnormally warm and dry spring conditions, combined with suppression of winter precipitation, can cause an early start of a fire season and high fire risk throughout the summer and fall. Therefore, it is crucial to investigate the connections between climate variability and wildfire danger characteristics. This study aims to identify climate variability using multiple climate indices such as NAO, El Niño-Southern Oscillation and the Pacific Decadal Oscillation closely related with droughts in the SWUS region. Correlation between the variability and fire frequency and severity in WUI were examined. Also, we investigated climate variability and its relationship on local wildfire potential using both Keetch-Byram Drought Index (KBDI) and Fire Weather Index (FWI) which have been used to assessing wildfire potential in the U.S.A and Canada, respectively. We examined the long-term variability of the fire potential indices and relationships between the indices and historical occurrence in WUI using multi-decadal reanalysis data sets. Following our analysis, we investigated joint impacts of multiple climate indices on droughts and human activities in the WUI for regional wildfire potential.

The eukaryotic bell-shaped temporal rate of DNA replication origin firing emanates from a balance between origin activation and passivation.

PubMed

Arbona, Jean-Michel; Goldar, Arach; Hyrien, Olivier; Arneodo, Alain; Audit, Benjamin

2018-06-01

The time-dependent rate I(t) of origin firing per length of unreplicated DNA presents a universal bell shape in eukaryotes that has been interpreted as the result of a complex time-evolving interaction between origins and limiting firing factors. Here we show that a normal diffusion of replication fork components towards localized potential replication origins (p-oris) can more simply account for the I(t) universal bell shape, as a consequence of a competition between the origin firing time and the time needed to replicate DNA separating two neighboring p-oris . We predict the I(t) maximal value to be the product of the replication fork speed with the squared p-ori density. We show that this relation is robustly observed in simulations and in experimental data for several eukaryotes. Our work underlines that fork-component recycling and potential origins localization are sufficient spatial ingredients to explain the universality of DNA replication kinetics. © 2018, Arbona et al.

Potential changes in forest composition could reduce impacts of climate change on boreal wildfires.

PubMed

Terrier, Aurélie; Girardin, Martin P; Périé, Catherine; Legendre, Pierre; Bergeron, Yves

2013-01-01

There is general consensus that wildfires in boreal forests will increase throughout this century in response to more severe and frequent drought conditions induced by climate change. However, prediction models generally assume that the vegetation component will remain static over the next few decades. As deciduous species are less flammable than conifer species, it is reasonable to believe that a potential expansion of deciduous species in boreal forests, either occurring naturally or through landscape management, could offset some of the impacts of climate change on the occurrence of boreal wildfires. The objective of this study was to determine the potential of this offsetting effect through a simulation experiment conducted in eastern boreal North America. Predictions of future fire activity were made using multivariate adaptive regression splines (MARS) with fire behavior indices and ecological niche models as predictor variables so as to take into account the effects of changing climate and tree distribution on fire activity. A regional climate model (RCM) was used for predictions of future fire risk conditions. The experiment was conducted under two tree dispersal scenarios: the status quo scenario, in which the distribution of forest types does not differ from the present one, and the unlimited dispersal scenario, which allows forest types to expand their range to fully occupy their climatic niche. Our results show that future warming will create climate conditions that are more prone to fire occurrence. However, unlimited dispersal of southern restricted deciduous species could reduce the impact of climate change on future fire occurrence. Hence, the use of deciduous species could be a good option for an efficient strategic fire mitigation strategy aimed at reducing fire Propagation in coniferous landscapes and increasing public safety in remote populated areas of eastern boreal Canada under climate change.

Climate refugia: The physical, hydrologic and disturbance basis

NASA Astrophysics Data System (ADS)

Holden, Z. A.; Maneta, M. P.; Forthofer, J.

2015-12-01

Projected changes in global climate and associated shifts in vegetation have increased interest in understanding species persistence at local scales. We examine the climatic and physical factors that could mediate changes in the distribution of vegetation in regions of complex topography. Using massive networks of low-cost temperature and humidity sensors, we developed topographically-resolved daily historical gridded temperature data for the US Northern Rockies. We used the WindNinja model to create daily historical wind speed maps across the same domain. Using a spatially distributed ecohydrology model (ECH2O) we examine separately the sensitivity of modeled evapotranspiration and soil moisture to wind, radiation, soil properties, minimum temperature and humidity. A suite of physical factors including lower wind speeds, cold air drainage, solar shading and increased soil depth reduce evapotranspiration and increase late season moisture availability in valley bottoms. Evapotranspiration shows strong sensitivity to spatial variability in surface wind speed, suggesting that sheltering effects from winds may be an important factor contributing to mountain refugia. Fundamental to our understanding of patterns of vegetation change is the role of stand-replacing wildfires, which modify the physical environment and subsequent patterns of species persistence and recruitment. Using satellite-derived maps of burn severity for recent fires in the US Northern Rockies we examined relationships between wind speed, cold air drainage potential and soil depth and the occurrence of unburned and low severity fire. Severe fire is less likely to occur in areas with high cold air drainage potential and low wind speeds, suggesting that sheltered valley bottoms have mediated the severity of recent wildfires. Our finding highlight the complex physical mechanisms by which mountain weather and climate mediate fire-induced vegetation changes in the US Northern Rocky Mountains.

Abrupt fire regime change may cause landscape-wide loss of mature obligate seeder forests.

PubMed

Bowman, David M J S; Murphy, Brett P; Neyland, Dominic L J; Williamson, Grant J; Prior, Lynda D

2014-03-01

Obligate seeder trees requiring high-severity fires to regenerate may be vulnerable to population collapse if fire frequency increases abruptly. We tested this proposition using a long-lived obligate seeding forest tree, alpine ash (Eucalyptus delegatensis), in the Australian Alps. Since 2002, 85% of the Alps bioregion has been burnt by several very large fires, tracking the regional trend of more frequent extreme fire weather. High-severity fires removed 25% of aboveground tree biomass, and switched fuel arrays from low loads of herbaceous and litter fuels to high loads of flammable shrubs and juvenile trees, priming regenerating stands for subsequent fires. Single high-severity fires caused adult mortality and triggered mass regeneration, but a second fire in quick succession killed 97% of the regenerating alpine ash. Our results indicate that without interventions to reduce fire severity, interactions between flammability of regenerating stands and increased extreme fire weather will eliminate much of the remaining mature alpine ash forest. © 2013 John Wiley & Sons Ltd.

Assessment of wildland fire impacts on watershed annual water yield: Analytical framework and case studies in the United States

Treesearch

Dennis W. Hallema; Ge Sun; Peter V. Caldwell; Steve Norman; Erika Cohen Mack; Yongqiang Liu; Eric J. Ward; Steve McNulty

2016-01-01

More than 50% of water supplies in the conterminous United States originate on forestland or rangeland, and are potentially under increasing stress as a result of larger and more severe wildfires. Little is known however about the long-term impacts of fire on annual water yield, and the role of climate variability within this context. We here propose a framework for...

[Influence of fire disturbance on aboveground deadwood debris carbon storage in Huzhong forest region of Great Xing'an Mountains, Northeast China].

PubMed

Yang, Da; He, Hong-shi; Wu, Zhi-wei; Liang, Yu; Huang, Chao; Luo, Xu; Xiao, Jiang-tao; Zhang, Qing-long

2015-02-01

Based on the field inventory data, the aboveground deadwood debris carbon storage under different fire severities was analyzed in Huzhong forest region of Great Xing' an Mountains. The results showed that the fire severity had a significant effect on aboveground deadwood debris carbon storage. The deadwood debris carbon storage was in the order of high-severity > low-severity > unburned in Larix gmelinii stands, and mixed conifer-broadleaf stands ( L. gmelinii and Betula platyphylla), and in the order of high severity > unburned > low-severity in B. platyphylla stands. Fire disturbance significantly changed the component percentage of the deadwood debris carbon storage. The component percentage of snags increased and litter decreased with the increasing fire severity. Logs and stumps did not change significantly with the increasing fire severity. The spatial variation of deadwood debris carbon storage in forests burned with low-severity fire was higher than that in unburned forests. The spatial variation of deadwood debris carbon storage with high-severity fires was lowest. This spatial variation needed to be accounted when calculating forest deadwood debris carbon storage.

Increasing elevation of fire in the Sierra Nevada and implications for forest change

USGS Publications Warehouse

Schwartz, Mark W.; Butt, Nathalie; Dolanc, Christopher R.; Holguin, Andrew; Moritz, Max A.; North, Malcolm P.; Safford, Hugh D.; Stephenson, Nathan L.; Thorne, James H.; van Mantgem, Phillip J.

2015-01-01

Fire in high-elevation forest ecosystems can have severe impacts on forest structure, function and biodiversity. Using a 105-year data set, we found increasing elevation extent of fires in the Sierra Nevada, and pose five hypotheses to explain this pattern. Beyond the recognized pattern of increasing fire frequency in the Sierra Nevada since the late 20th century, we find that the upper elevation extent of those fires has also been increasing. Factors such as fire season climate and fuel build up are recognized potential drivers of changes in fire regimes. Patterns of warming climate and increasing stand density are consistent with both the direction and magnitude of increasing elevation of wildfire. Reduction in high elevation wildfire suppression and increasing ignition frequencies may also contribute to the observed pattern. Historical biases in fire reporting are recognized, but not likely to explain the observed patterns. The four plausible mechanistic hypotheses (changes in fire management, climate, fuels, ignitions) are not mutually exclusive, and likely have synergistic interactions that may explain the observed changes. Irrespective of mechanism, the observed pattern of increasing occurrence of fire in these subalpine forests may have significant impacts on their resilience to changing climatic conditions.

Analysis of the prescribed burning practice in the pine forest of northwestern Portugal.

PubMed

Fernandes, P; Botelho, H

2004-01-01

The ignition of low-intensity fires in the dormant season in the pine stands of north-western Portugal seeks to reduce the existing fuel hazard without compromising site quality. The purpose of this study is to characterise this practice and assess its effectiveness, based on information resulting from the normal monitoring process at the management level, and using operational guidelines, fire behaviour models and a newly developed method to classify prescribed fire severity. Although the region's humid climate strongly constrains the activity of prescribed fire, 87% of the fires analysed were undertaken under acceptable meteorological and fuel moisture conditions. In fact, most operations achieved satisfactory results. On average, prescribed fire reduces by 96% the potential intensity of a wildfire occurring under extreme weather conditions, but 36% of the treated sites would still require heavy fire fighting resources to suppress such fire, and 17% would still carry it in the tree canopy. Only 10% of the prescribed burns have an excessive impact on trees or the forest floor, while 89% (normal fire weather) or 59% (extreme fire weather) comply with both ecological integrity maintenance and wildfire protection needs. Improved planning and monitoring procedures are recommended in order to overcome the current deficiencies.

Wood crib fire free burning test in ISO room

NASA Astrophysics Data System (ADS)

Qiang, Xu; Griffin, Greg; Bradbury, Glenn; Dowling, Vince

2006-04-01

In the research of application potential of water mist fire suppression system for fire fighting in train luggage carriage, a series of experiments were conducted in ISO room on wood crib fire with and without water mist actuation. The results of free burn test without water mist suppression are used as reference in evaluating the efficiency of water mist suppression system. As part of the free burn test, several tests have been done under the hood of ISO room to calibrate the size of the crib fire and these tests can also be used in analyzing the wall effect in room fire hazard. In these free burning experiments, wood cribs of four sizes under the hood were tested. The temperature of crib fire, heat flux around the fire, gas concentration in hood of ISO room were measured in the experiments and two sets of thermal imaging system were used to get the temperature distribution and the typical shape of the free burning flames. From the experiments, the radiation intensity in specific positions around the fire, the effective heat of combustion, mass loss, oxygen consumption rate for different sizes of fire, typical structure of the flame and self extinguishment time was obtained for each crib size.

Modeling fire occurrence as a function of landscape

NASA Astrophysics Data System (ADS)

Loboda, T. V.; Carroll, M.; DiMiceli, C.

2011-12-01

Wildland fire is a prominent component of ecosystem functioning worldwide. Nearly all ecosystems experience the impact of naturally occurring or anthropogenically driven fire. Here, we present a spatially explicit and regionally parameterized Fire Occurrence Model (FOM) aimed at developing fire occurrence estimates at landscape and regional scales. The model provides spatially explicit scenarios of fire occurrence based on the available records from fire management agencies, satellite observations, and auxiliary geospatial data sets. Fire occurrence is modeled as a function of the risk of ignition, potential fire behavior, and fire weather using internal regression tree-driven algorithms and empirically established, regionally derived relationships between fire occurrence, fire behavior, and fire weather. The FOM presents a flexible modeling structure with a set of internal globally available default geospatial independent and dependent variables. However, the flexible modeling environment adapts to ingest a variable number, resolution, and content of inputs provided by the user to supplement or replace the default parameters to improve the model's predictive capability. A Southern California FOM instance (SC FOM) was developed using satellite assessments of fire activity from a suite of Landsat and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data, Monitoring Trends in Burn Severity fire perimeters, and auxiliary geospatial information including land use and ownership, utilities, transportation routes, and the Remote Automated Weather Station data records. The model was parameterized based on satellite data acquired between 2001 and 2009 and fire management fire perimeters available prior to 2009. SC FOM predictive capabilities were assessed using observed fire occurrence available from the MODIS active fire product during 2010. The results show that SC FOM provides a realistic estimate of fire occurrence at the landscape level: the fraction of area impacted by fire from the total available area within a given value of the Fire Occurrence Index (FOI) increased from 9.e-06 at FOI < 3 to 28.e-06 at 25 < FOI <= 28. Additionally, the model has revealed a new important relationship between fire occurrence, anthropogenic activity, and fire weather. Data analysis has demonstrated that human activity can alter the expected weather/fire occurrence relationships and result in considerable modifications of fire regimes contrary to the assumed ecological parameters. Specifically, between 2001 and 2009 over 50% of total fire impacted area burned during the low fire danger conditions (Canadian Fire Weather Index < 5). These findings and the FOM capabilities offer a new theoretical construct and an advanced tool for assessing the potential impacts of climate changes on fire regimes, particularly within landscapes which are impacted strongly by human activities. Future development of the FOM will focus on ingesting and internal downscaling of climate variables produced by General or Regional Circulation Models to develop scenarios of potential future change in fire occurrence under the influence of projected climate change at the appropriate regional or landscape scales.

Southwestern Oregon's Biscuit Fire: An Analysis of Forest Resources, Fire Severity, and Fire Hazard

Treesearch

David L. Azuma; Glenn A. Christensen

2005-01-01

This study compares pre-fire field inventory data (collected from 1993 to 1997) in relation to post-fire mapped fire severity classes and the Fire and Fuels Extension of the Forest Vegetation Simulator growth and yield model measures of fire hazard for the portion of the Siskiyou National Forest in the 2002 Biscuit fire perimeter of southwestern Oregon. Post-fire...

Avian response to fire in pine–oak forests of Great Smoky Mountains National Park following decades of fire suppression

USGS Publications Warehouse

Rose, Eli T.; Simons, Theodore R.

2016-01-01

Fire suppression in southern Appalachian pine–oak forests during the past century dramatically altered the bird community. Fire return intervals decreased, resulting in local extirpation or population declines of many bird species adapted to post-fire plant communities. Within Great Smoky Mountains National Park, declines have been strongest for birds inhabiting xeric pine–oak forests that depend on frequent fire. The buildup of fuels after decades of fire suppression led to changes in the 1996 Great Smoky Mountains Fire Management Plan. Although fire return intervals remain well below historic levels, management changes have helped increase the amount of fire within the park over the past 20 years, providing an opportunity to study patterns of fire severity, time since burn, and bird occurrence. We combined avian point counts in burned and unburned areas with remote sensing indices of fire severity to infer temporal changes in bird occurrence for up to 28 years following fire. Using hierarchical linear models that account for the possibility of a species presence at a site when no individuals are detected, we developed occurrence models for 24 species: 13 occurred more frequently in burned areas, 2 occurred less frequently, and 9 showed no significant difference between burned and unburned areas. Within burned areas, the top models for each species included fire severity, time since burn, or both, suggesting that fire influenced patterns of species occurrence for all 24 species. Our findings suggest that no single fire management strategy will suit all species. To capture peak occupancy for the entire bird community within xeric pine–oak forests, at least 3 fire regimes may be necessary; one applying frequent low severity fire, another using infrequent low severity fire, and a third using infrequently applied high severity fire.

Distribution and relative abundance of forest birds in relation to burn severity in southeastern Arizona

USGS Publications Warehouse

Kirkpatrick, C.; Conway, C.J.; Jones, P.B.

2006-01-01

The frequency of wild and prescribed fires in montane forests of the southwestern United States has increased after a century of fire suppression and subsequent fuels accumulation. To assess the effects of recent fires (median time since fire = 6 yr) on the montane forest bird community, we surveyed birds in 8 Sky Island mountain ranges in southeastern Arizona, USA, and examined how the distribution (i.e., presence-absence) of 65 species and relative abundance of 16 species correlated with evidence of severe and less severe fire at >1,500 survey points. We detected associations between fire and bird presence-absence for 17% of the 65 species analyzed and between fire and bird relative abundance for 25% of the 16 species analyzed. Most species (73%) were positively associated with burned areas and displayed stronger associations (i.e., more extreme odds ratios) with survey points that had evidence of severe as opposed to less severe fire. Positive associations with severe fire were strong (>3 to 1 odds) for western wood-pewee (Contopus sordidulus) and house wren (Troglodytes aedon), and negative associations with severe fire were strong for warbling vireo (Vireo gilvus) and red-breasted nuthatch (Sitta canadensis). Although recent fires appear to have had a positive effect on the distribution and relative abundance of several montane forest bird species in the region, these species are not the open-woodland birds that we would have expected to have benefited from fire based on previous research. Nevertheless, our results confirm associations between fire and bird presence-absence and relative abundance reported previously for 7 species of birds. Our results also provide new information for Grace's warbler (Dendroica graciae) and greater pewee (C. pertinax), 2 species for which fire data were formerly lacking. Managers can use these data to make and test predictions about the effects of future fires, both severe and less severe, on montane forest birds in the southwestern United States.

Examining Historical and Current Mixed-Severity Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America

PubMed Central

Odion, Dennis C.; Hanson, Chad T.; Arsenault, André; Baker, William L.; DellaSala, Dominick A.; Hutto, Richard L.; Klenner, Walt; Moritz, Max A.; Sherriff, Rosemary L.; Veblen, Thomas T.; Williams, Mark A.

2014-01-01

There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to “restore” forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa pine and mixed-conifer forests of western North America. PMID:24498383

Examining historical and current mixed-severity fire regimes in ponderosa pine and mixed-conifer forests of western North America.

PubMed

Odion, Dennis C; Hanson, Chad T; Arsenault, André; Baker, William L; Dellasala, Dominick A; Hutto, Richard L; Klenner, Walt; Moritz, Max A; Sherriff, Rosemary L; Veblen, Thomas T; Williams, Mark A

2014-01-01

There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to "restore" forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa pine and mixed-conifer forests of western North America.

Fire Severity and Soil Carbon Combustion in Boreal and Tundra Ecosystems

NASA Astrophysics Data System (ADS)

Walker, X. J.; Mack, M. C.; Baltzer, J. L.; Cummings, S.; Day, N.; Goetz, S.; Johnstone, J. F.; Rogers, B. M.; Turetsky, M. R.

2016-12-01

Climate warming in northern latitudes has led to an intensification of wildfire disturbance. Increased fire frequency, extent, and severity is expected to strongly impact the structure and function of northern ecosystems. In this study, we examined 50 sites in a recently burned tundra ecosystem of Alaska, USA and 250 sites in recently burned boreal conifer forest ecosystems of Northwest Territories, Canada. The majority of organic carbon (C) in both boreal and tundra ecosystems resides in the soil organic layer (SOL) and combustion of this layer can lead to large C emissions. Through examining multiple fire scars in different regions, ranging in moisture, elevation, and pre-fire vegetation communities, we can determine the ecosystem, landscape, and regional controls on SOL combustion and the potential shift in C storage. In this research, we use scalable SOL consumption metrics to estimate depth of burn and the associated C emissions. Preliminary results from boreal conifer sites indicate that nearly 50% of the pre-fire soil C pool was combusted and that over 75% of the total C emitted from the extreme fire year of 2014 can be attributed to combustion of the SOL. Increased combustion of SOL associated with an intensifying fire regime could shift boreal and tundra ecosystems across a C cycle threshold: from net accumulation of C from the atmosphere over multiple fire cycles, to a net loss. Understanding changes in SOL combustion and C storage is essential for assessing the consequences of an altered fire regime on permafrost dynamics, vegetation regeneration, and the initiation of successional trajectories in tundra and boreal ecosystems.

Oxygen Compatibility Assessment of Components and Systems

NASA Technical Reports Server (NTRS)

Stoltzfus, Joel; Sparks, Kyle

2010-01-01

Fire hazards are inherent in oxygen systems and a storied history of fires in rocket engine propulsion components exists. To detect and mitigate these fire hazards requires careful, detailed, and thorough analyses applied during the design process. The oxygen compatibility assessment (OCA) process designed by NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) can be used to determine the presence of fire hazards in oxygen systems and the likelihood of a fire. This process may be used as both a design guide and during the approval process to ensure proper design features and material selection. The procedure for performing an OCA is a structured step-by-step process to determine the most severe operating conditions; assess the flammability of the system materials at the use conditions; evaluate the presence and efficacy of ignition mechanisms; assess the potential for a fire to breach the system; and determine the reaction effect (the potential loss of life, mission, and system functionality as the result of a fire). This process should be performed for each component in a system. The results of each component assessment, and the overall system assessment, should be recorded in a report that can be used in the short term to communicate hazards and their mitigation and to aid in system/component development and, in the long term, to solve anomalies that occur during engine testing and operation.

Anaphylaxis

MedlinePlus

... Bees Wasps Hornets Yellow jackets Fire ants Medicines Antibiotics and antiseizure medicines are some of the more common medicines that cause anaphylaxis. However, any medicine, even aspirin and other nonsteroidal anti-inflammatory drugs, have the potential to cause severe reactions. ...

Interactions among livestock grazing, vegetation type, and fire behavior in the Murphy Wildland Fire Complex in Idaho and Nevada, July 2007

USGS Publications Warehouse

Launchbaugh, Karen; Brammer, Bob; Brooks, Matthew L.; Bunting, Stephen C.; Clark, Patrick; Davison, Jay; Fleming, Mark; Kay, Ron; Pellant, Mike; Pyke, David A.

2008-01-01

A series of wildland fires were ignited by lightning in sagebrush and grassland communities near the Idaho-Nevada border southwest of Twin Falls, Idaho in July 2007. The fires burned for over two weeks and encompassed more than 650,000 acres. A team of scientists, habitat specialists, and land managers was called together by Tom Dyer, Idaho BLM State Director, to examine initial information from the Murphy Wildland Fire Complex in relation to plant communities and patterns of livestock grazing. Three approaches were used to examine this topic: (1) identify potential for livestock grazing to modify fuel loads and affect fire behavior using fire models applied to various vegetation types, fuel loads, and fire conditions; (2) compare levels of fuel consumed within and among major vegetation types; and (3) examine several observed lines of difference and discontinuity in fuel consumed to determine what factors created these contrasts. The team found that much of the Murphy Wildland Fire Complex burned under extreme fuel and weather conditions that likely overshadowed livestock grazing as a factor influencing fire extent and fuel consumption in many areas where these fires burned. Differences and abrupt contrast lines in the level of fuels consumed were affected mostly by the plant communities that existed on a site before fire. A few abrupt contrasts in burn severity coincided with apparent differences in grazing patterns of livestock, observed as fence-line contrasts. Fire modeling revealed that grazing in grassland vegetation can reduce surface rate of spread and fire-line intensity to a greater extent than in shrubland types. Under extreme fire conditions (low fuel moisture, high temperatures, and gusty winds), grazing applied at moderate utilization levels has limited or negligible effects on fire behavior. However, when weather and fuel-moisture conditions are less extreme, grazing may reduce the rate of spread and intensity of fires allowing for patchy burns with low levels of fuel consumption. The team suggested that targeted grazing to accomplish fuel objectives holds promise but requires detailed planning that includes clearly defined goals for fuel modification and appropriate monitoring to assess effectiveness. It was recommended that a pilot plan be devised to strategically place grazed blocks across a landscape to create fuel-reduction bands capable of influencing fire behavior. Also suggested was the development of a general technical report that highlights information and examples of how livestock grazing influences fire extent, severity, and intensity. Finally, the team encouraged continued research and monitoring of the effects of the Murphy Wildland Fire Complex. Much more can be learned from the effects of this extensive fire complex that may offer insight for future management decisions.

The Zoning of Forest Fire Potential of Gulestan Province Forests Using Granular Computing and MODIS Images

NASA Astrophysics Data System (ADS)

Jalilzadeh Shadlouei, A.; Delavar, M. R.

2013-09-01

There are many vegetation in Iran. This is because of extent of Iran and its width. One of these vegetation is forest vegetation most prevalent in Northern provinces named Guilan, Mazandaran, Gulestan, Ardebil as well as East Azerbaijan. These forests are always threatened by natural forest fires so much so that there have been reports of tens of fires in recent years. Forest fires are one of the major environmental as well as economic, social and security concerns in the world causing much damages. According to climatology, forest fires are one of the important factors in the formation and dispersion of vegetation. Also, regarding the environment, forest fires cause the emission of considerable amounts of greenhouse gases, smoke and dust into the atmosphere which in turn causes the earth temperature to rise up and are unhealthy to humans, animals and vegetation. In agriculture droughts are the usual side effects of these fires. The causes of forest fires could be categorized as either Human or Natural Causes. Naturally, it is impossible to completely contain forest fires; however, areas with high potentials of fire could be designated and analysed to decrease the risk of fires. The zoning of forest fire potential is a multi-criteria problem always accompanied by inherent uncertainty like other multi-criteria problems. So far, various methods and algorithm for zoning hazardous areas via Remote Sensing (RS) and Geospatial Information System (GIS) have been offered. This paper aims at zoning forest fire potential of Gulestan Province of Iran forests utilizing Remote Sensing, Geospatial Information System, meteorological data, MODIS images and granular computing method. Granular computing is part of granular mathematical and one way of solving multi-criteria problems such forest fire potential zoning supervised by one expert or some experts , and it offers rules for classification with the least inconsistencies. On the basis of the experts' opinion, 6 determinative criterias contributing to forest fires have been designated as follows: vegetation (NDVI), slope, aspect, temperature, humidity and proximity to roadways. By applying these variables on several tentatively selected areas and formation information tables and producing granular decision tree and extraction of rules, the zoning rules (for the areas in question) were extracted. According to them the zoning of the entire area has been conducted. The zoned areas have been classified into 5 categories: high hazard, medium hazard (high), medium hazard (low), low hazard (high), low hazard (low). According to the map, the zoning of most of the areas fall into the low hazard (high) class while the least number of areas have been classified as low hazard (low). Comparing the forest fires in these regions in 2010 with the MODIS data base for forest fires, it is concluded that areas with high hazards of forest fire have been classified with a 64 percent precision. In other word 64 percent of pixels that are in high hazard classification are classified according to MODIS data base. Using this method we obtain a good range of Perception. Manager will reduce forest fire concern using precautionary proceeding on hazardous area.

Increasing fire severity, alternate successional trajectories, and the carbon balance of Alaskan boreal forests

NASA Astrophysics Data System (ADS)

Mack, M. C.; Alexander, H. D.; Jean, M.; Melvin, A. M.; Johnstone, J. F.

2016-12-01

Climate-sensitive disturbances, such as wildfire, can feed back positively to climate warming via the carbon (C) cycle if C released by disturbance is not replaced over post-fire succession. In boreal forests, burning of carbon in deep organic soils is not only an important determinate of ecosystem element balance over the disturbance cycle, but also sets the conditions that control plant recruitment, species dominance and successional trajectory. Species dominance, in turn, has the potential to exert strong control over the plant-soil-microbial feedbacks that determine C and nutrient coupling, C storage, and ultimately, replacement of combusted C. We examined the consequences of increasing fire severity for C balance and C and nitrogen (N) coupling in Alaskan boreal forests. We estimated combustion losses in 90 black spruce (conifer) stands that burned in 2004. Over the next decade, we followed natural tree seedling establishment in these stands and used seedling species dominance identify conifer versus deciduous successional trajectories. We assembled data from 120 stands that varied in time after fire and successional trajectory, and estimated C and N dynamics across 150 years of post-fire succession for each trajectory. Conifer stands that burned with high severity transitioned to deciduous tree dominance after fire. These stands had smaller ecosystem pools of C and N before fire, lost a larger proportion of these pools during the fire, and began succession with smaller residual pools than stands that returned to conifer dominance after fire. Over secondary succession, deciduous stands accumulated about 10 times more carbon in aboveground biomass than conifer stands. Belowground biomass and soil carbon accumulation, by contrast, was about three times higher in the black spruce stands than in deciduous stands. As a result, net ecosystem C accumulation over the 100 year inter-fire interval was three times higher in deciduous stands than in coniferous stands. Nitrogen accumulation did not differ between the trajectories; high C:N ratio biomass accumulation in deciduous stands balanced low C:N ratio soil organic matter accumulation in conifer stands. The timing of N accumulation, however, differed substantially, supporting the idea that deciduous stands mine N from degrading permafrost after fire.

Incorporating Resource Protection Constraints in an Analysis of Landscape Fuel-Treatment Effectiveness in the Northern Sierra Nevada, CA, USA.

PubMed

Dow, Christopher B; Collins, Brandon M; Stephens, Scott L

2016-03-01

Finding novel ways to plan and implement landscape-level forest treatments that protect sensitive wildlife and other key ecosystem components, while also reducing the risk of large-scale, high-severity fires, can prove to be difficult. We examined alternative approaches to landscape-scale fuel-treatment design for the same landscape. These approaches included two different treatment scenarios generated from an optimization algorithm that reduces modeled fire spread across the landscape, one with resource-protection constrains and one without the same. We also included a treatment scenario that was the actual fuel-treatment network implemented, as well as a no-treatment scenario. For all the four scenarios, we modeled hazardous fire potential based on conditional burn probabilities, and projected fire emissions. Results demonstrate that in all the three active treatment scenarios, hazardous fire potential, fire area, and emissions were reduced by approximately 50 % relative to the untreated condition. Results depict that incorporation of constraints is more effective at reducing modeled fire outputs, possibly due to the greater aggregation of treatments, creating greater continuity of fuel-treatment blocks across the landscape. The implementation of fuel-treatment networks using different planning techniques that incorporate real-world constraints can reduce the risk of large problematic fires, allow for landscape-level heterogeneity that can provide necessary ecosystem services, create mixed forest stand structures on a landscape, and promote resilience in the uncertain future of climate change.

Impact of anthropogenic climate change on wildfire across western US forests

PubMed Central

Williams, A. Park

2016-01-01

Increased forest fire activity across the western continental United States (US) in recent decades has likely been enabled by a number of factors, including the legacy of fire suppression and human settlement, natural climate variability, and human-caused climate change. We use modeled climate projections to estimate the contribution of anthropogenic climate change to observed increases in eight fuel aridity metrics and forest fire area across the western United States. Anthropogenic increases in temperature and vapor pressure deficit significantly enhanced fuel aridity across western US forests over the past several decades and, during 2000–2015, contributed to 75% more forested area experiencing high (>1 σ) fire-season fuel aridity and an average of nine additional days per year of high fire potential. Anthropogenic climate change accounted for ∼55% of observed increases in fuel aridity from 1979 to 2015 across western US forests, highlighting both anthropogenic climate change and natural climate variability as important contributors to increased wildfire potential in recent decades. We estimate that human-caused climate change contributed to an additional 4.2 million ha of forest fire area during 1984–2015, nearly doubling the forest fire area expected in its absence. Natural climate variability will continue to alternate between modulating and compounding anthropogenic increases in fuel aridity, but anthropogenic climate change has emerged as a driver of increased forest fire activity and should continue to do so while fuels are not limiting. PMID:27791053

Burn severity mapping using simulation modeling and satellite imagery

Treesearch

Eva C. Karau; Robert E. Keane

2010-01-01

Although burn severity maps derived from satellite imagery provide a landscape view of fire impacts, fire effects simulation models can provide spatial fire severity estimates and add a biotic context in which to interpret severity. In this project, we evaluated two methods of mapping burn severity in the context of rapid post-fire assessment for four wildfires in...

Effects of active forest fire on terrestrial ecosystem production and greenhouse gas emissions

NASA Astrophysics Data System (ADS)

Sannigrahi, Srikanta; Rahmat, Shahid; Bhatt, Sandeep; Rana, Virendra

2017-04-01

The forest fire is one of the most catalysing agents which degrade an ecosystems leading to the loss of net and gross primary productivity (NPP & GPP) and carbon sequestration service. Additionally, it can suppress the efficiency of service providing capacity of an ecosystem throughout the time and space. Remote sensing-based forest fire estimation in a diverse ecosystem is very much essential for mitigating the biodiversity and productivity losses due to the forest fire. Satellite-based Land Surface Temperature (LST) has been calculated for the pre-fire and fire years to identify the burn severity hotspot across all eco-regions in the Lower Himalaya region. Several burn severity indices: Normalized Burn Ratio (NBR), Burnt Area Index (BAI), Normalized Multiband Drought Index (NMDI), Soil Adjusted Vegetation Index (SAVI), Global Environmental Monitoring Index (GEMI), Enhance Vegetation Index (EVI) have been used in this study to quantify the spatial and temporal changes (delta) of the selected indices. Two Light Use Efficiency (LUE) models: Carnegie- Ames-Stanford-Approach (CASA) and Vegetation Photosynthesis Model (VPM) have been used to quantify the terrestrial Net Primary Productivity (NPP) in the pre-fire and fire years across all biomes of the region. A novel approach has been preceded in this field to demonstrate the correlation between forest fire density (FFD) and NPP. A strong positive correlation was found between burn severity indices and predicted NPP: BAI and NPP (r = 0.49), NBR and NPP: (r = 0.58), EVI and NPP: (r = 0.72), SAVI and NPP: (r = 0.67), whereas, a negative association has noted between the NMDI and NPP: (r = -0.36) during the both studied years. Results have shown that the NPP is highly correlated with the forest fire density (R2 = 0.75, RMSE = 5.03 gC m-2 month-1). The estimated LST of the individual fire days has witnessed a sharp temperature increase by > 6oC - 9oC in comparison to the non-fire days clearly indicates high fire risk (in Uttarakhand) due to the subtle water stress condition with lesser soil moisture content into the ground. Among the 13 districts, the maximum net emissions of carbon and nitrogen compounds have been observed in 7 districts (accounting for high biomass and forest cover loss by the 2016 forest fire), whereas, the rest of the 6 districts acts as the sequester of greenhouse compounds. This new approach having the potentiality of quantifying the losses of ecosystem productivity due to forest fires and could be used in broader aspects if more accurate field based observation can be obtained in the near future.

Effect of prior disturbances on the extent and severity of wildfire in Colorado subalpine forests.

PubMed

Kulakowski, Dominik; Veblen, Thomas T

2007-03-01

Disturbances are important in creating spatial heterogeneity of vegetation patterns that in turn may affect the spread and severity of subsequent disturbances. Between 1997 and 2002 extensive areas of subalpine forests in northwestern Colorado were affected by a blowdown of trees, bark beetle outbreaks, and salvage logging. Some of these stands were also affected by severe fires in the late 19th century. During a severe drought in 2002, fires affected extensive areas of these subalpine forests. We evaluated and modeled the extent and severity of the 2002 fires in relation to these disturbances that occurred over the five years prior to the fires and in relation to late 19th century stand-replacing fires. Occurrence of disturbances prior to 2002 was reconstructed using a combination of tree-ring methods, aerial photograph interpretation, field surveys, and geographic information systems (GIS). The extent and severity of the 2002 fires were based on the normalized difference burn ratio (NDBR) derived from satellite imagery. GIS and classification trees were used to analyze the effects of prefire conditions on the 2002 fires. Previous disturbance history had a significant influence on the severity of the 2002 fires. Stands that were severely blown down (> 66% trees down) in 1997 burned more severely than other stands, and young (approximately 120 year old) postfire stands burned less severely than older stands. In contrast, prefire disturbances were poor predictors of fire extent, except that young (approximately 120 years old) postfire stands were less extensively burned than older stands. Salvage logging and bark beetle outbreaks that followed the 1997 blowdown (within the blowdown as well as in adjacent forest that was not blown down) did not appear to affect fire extent or severity. Conclusions regarding the influence of the beetle outbreaks on fire extent and severity are limited, however, by spatial and temporal limitations associated with aerial detection surveys of beetle activity. Thus, fire extent in these forests is largely independent of prefire disturbance history and vegetation conditions. In contrast, fire severity, even during extreme fire weather and in conjunction with a multiyear drought, is influenced by prefire stand conditions, including the history of previous disturbances.

Application of the Haines Index in the fire warning system

NASA Astrophysics Data System (ADS)

Kalin, Lovro; Marija, Mokoric; Tomislav, Kozaric

2016-04-01

Croatia, as all Mediterranean countries, is strongly affected by large wildfires, particularly in the coastal region. In the last two decades the number and intensity of fires has been significantly increased, which is unanimously associated with climate change, e.g. global warming. More extreme fires are observed, and the fire-fighting season has been expanded to June and September. The meteorological support for fire protection and planning is therefore even more important. At the Meteorological and Hydrological Service of Croatia a comprehensive monitoring and warning system has been established. It includes standard components, such as short term forecast of Fire Weather Index (FWI), but long range forecast as well. However, due to more frequent hot and dry seasons, FWI index often does not provide additional information of extremely high fire danger, since it regularly takes the highest values for long periods. Therefore the additional tools have been investigated. One of widely used meteorological products is the Haines index (HI). It provides information of potential fire growth, taking into account only the vertical instability of the atmosphere, and not the state of the fuel. Several analyses and studies carried out at the Service confirmed the correlation of high HI values with large and extreme fires. The Haines index forecast has been used at the Service for several years, employing European Centre for Medium Range Weather Forecast (ECMWF) global prediction model, as well as the limited-area Aladin model. The verification results show that these forecast are reliable, when compared to radiosonde measurements. All these results provided the introduction of the additional fire warnings, that are issued by the Service's Forecast Department.

Seed invasion filters and forest fire severity

Treesearch

Tom R. Cottrell; Paul F. Hessburg; Jonathan A. Betz

2008-01-01

Forest seed dispersal is altered after fire. Using seed traps, we studied impacts of fire severity on timing of seed dispersal, total seed rain, and seed rain richness in patches of high and low severity fire and unburned Douglas-fir (Pseudotsuga menziesii) forests in the Fischer and Tyee fire complexes in the eastern Washington Cascades. Unburned...

Assessing post-fire ground cover in Mediterranean shrublands with field spectrometry and digital photography

NASA Astrophysics Data System (ADS)

Montorio Llovería, Raquel; Pérez-Cabello, Fernando; García-Martín, Alberto

2016-09-01

Fire severity can be assessed by identifying and quantifying the fractional abundance of post-fire ground cover types, an approach with great capacity to predict ecosystem response. Focused on shrubland formations of Mediterranean-type ecosystems, three burned areas (Ibieca and Zuera wildfires and Peñaflor experimental fire) were sampled in the summers of 2006 and 2007. Two different ground measurements were made for each of the 356 plots: (i) 3-band high spatial resolution photography (HSRP) and (ii) the hemispherical-conical reflectance factor (HCRF) in the visible to near-infrared spectral range (VNIR, 400-900 nm). Stepwise multiple lineal regression (SMLR) models were fitted to spectral variables (HCRF, first derivative spectra or FDS, and four absorption indices) to estimate the fractional cover of seven post-fire ground cover types (vegetation and soil - unburned and charred components - and ash - char and ash, individually and as a combined category). Models were developed and validated at the Peñaflor site (training, n = 217; validation, n = 88) and applied to the samples from the Ibieca and Zuera sites (n = 51). The best results were observed for the abundance estimations of green vegetation (Radj.20.70-0.90), unburned soil (Radj.20.40-0.75), and the combination of ashes (Radj.20.65-0.80). In comparison of spectral data, FDS outperforms reflectance or absorption data because of its higher accuracy levels and, importantly, its greater capacity to yield generalizable models. Future efforts should be made to improve the estimation of intermediate severity levels and upscaling the developed models. In the context of fire severity assessment, our study demonstrates the potential of hyperspectral data to estimate in a quick and objective manner post-fire ground cover fractions and thus provide valuable information to guide management responses.

Quantifying the fire regime distributions for severity in Yosemite National Park, California, USA

USGS Publications Warehouse

Thode, Andrea E.; van Wagtendonk, Jan W.; Miller, Jay D.; Quinn, James F.

2011-01-01

This paper quantifies current fire severity distributions for 19 different fire-regime types in Yosemite National Park, California, USA. Landsat Thematic Mapper remote sensing data are used to map burn severity for 99 fires (cumulatively over 97 000 ha) that burned in Yosemite over a 20-year period. These maps are used to quantify the frequency distributions of fire severity by fire-regime type. A classification is created for the resultant distributions and they are discussed within the context of four vegetation zones: the foothill shrub and woodland zone; the lower montane forest zone; the upper montane forest zone and the subalpine forest zone. The severity distributions can form a building block from which to discuss current fire regimes across the Sierra Nevada in California. This work establishes a framework for comparing the effects of current fires on our landscapes with our notions of how fires historically burned, and how current fire severity distributions differ from our desired future conditions. As this process is refined, a new set of information will be available to researchers and land managers to help understand how fire regimes have changed from the past and how we might attempt to manage them in the future.

Forest fire weather and computed fire occurrence in western Oregon and western Washington in 1960.

Treesearch

Owen P. Cramer

1960-01-01

Fire season severity in 1960 was about average in western Washington but was very high in western Oregon. Severity of the entire season in both States was slightly greater than in 1959. Although spring was less severe, both summer and fall were slightly more severe than comparable parts of the previous fire season. Spring fire danger in western Washington was as low as...

Disturbance and productivity interactions mediate stability of forest composition and structure.

PubMed

O'Connor, Christopher D; Falk, Donald A; Lynch, Ann M; Swetnam, Thomas W; Wilcox, Craig P

2017-04-01

Fire is returning to many conifer-dominated forests where species composition and structure have been altered by fire exclusion. Ecological effects of these fires are influenced strongly by the degree of forest change during the fire-free period. Response of fire-adapted species assemblages to extended fire-free intervals is highly variable, even in communities with similar historical fire regimes. This variability in plant community response to fire exclusion is not well understood; however, ecological mechanisms such as individual species' adaptations to disturbance or competition and underlying site characteristics that facilitate or impede establishment and growth have been proposed as potential drivers of assemblage response. We used spatially explicit dendrochronological reconstruction of tree population dynamics and fire regimes to examine the influence of historical disturbance frequency (a proxy for adaptation to disturbance or competition), and potential site productivity (a proxy for underlying site characteristics) on the stability of forest composition and structure along a continuous ecological gradient of pine, dry mixed-conifer, mesic mixed-conifer, and spruce-fir forests following fire exclusion. While average structural density increased in all forests, species composition was relatively stable in the lowest productivity pine-dominated and highest productivity spruce-fir-dominated sites immediately following fire exclusion and for the next 100 years, suggesting site productivity as a primary control on species composition and structure in forests with very different historical fire regimes. Species composition was least stable on intermediate productivity sites dominated by mixed-conifer forests, shifting from primarily fire-adapted species to competition-adapted, fire-sensitive species within 20 years of fire exclusion. Rapid changes to species composition and stand densities have been interpreted by some as evidence of high-severity fire. We demonstrate that the very different ecological process of fire exclusion can produce similar changes by shifting selective pressures from disturbance-mediated to productivity-mediated controls. Restoring disturbance-adapted species composition and structure to intermediate productivity forests may help to buffer them against projected increasing temperatures, lengthening fire seasons, and more frequent and prolonged moisture stress. Fewer management options are available to promote adaptation in forest assemblages historically constrained by underlying site productivity. © 2016 by the Ecological Society of America.

Modeling the impacts of wildfire on runoff and pollutant transport from coastal watersheds to the nearshore environment.

PubMed

Morrison, Katherine D; Kolden, Crystal A

2015-03-15

Wildfire is a common disturbance that can significantly alter vegetation in watersheds and affect the rate of sediment and nutrient transport to adjacent nearshore oceanic environments. Changes in runoff resulting from heterogeneous wildfire effects are not well-understood due to both limitations in the field measurement of runoff and temporally-limited spatial data available to parameterize runoff models. We apply replicable, scalable methods for modeling wildfire impacts on sediment and nonpoint source pollutant export into the nearshore environment, and assess relationships between wildfire severity and runoff. Nonpoint source pollutants were modeled using a GIS-based empirical deterministic model parameterized with multi-year land cover data to quantify fire-induced increases in transport to the nearshore environment. Results indicate post-fire concentration increases in phosphorus by 161 percent, sediments by 350 percent and total suspended solids (TSS) by 53 percent above pre-fire years. Higher wildfire severity was associated with the greater increase in exports of pollutants and sediment to the nearshore environment, primarily resulting from the conversion of forest and shrubland to grassland. This suggests that increasing wildfire severity with climate change will increase potential negative impacts to adjacent marine ecosystems. The approach used is replicable and can be utilized to assess the effects of other types of land cover change at landscape scales. It also provides a planning and prioritization framework for management activities associated with wildfire, including suppression, thinning, and post-fire rehabilitation, allowing for quantification of potential negative impacts to the nearshore environment in coastal basins. Copyright © 2014 Elsevier Ltd. All rights reserved.

Forest restoration as a strategy to mitigate climate impacts on wildfire, vegetation, and water in semiarid forests.

PubMed

O'Donnell, Frances C; Flatley, William T; Springer, Abraham E; Fulé, Peter Z

2018-06-25

Climate change and wildfire are interacting to drive vegetation change and potentially reduce water quantity and quality in the southwestern United States, Forest restoration is a management approach that could mitigate some of these negative outcomes. However, little information exists on how restoration combined with climate change might influence hydrology across large forest landscapes that incorporate multiple vegetation types and complex fire regimes. We combined spatially explicit vegetation and fire modeling with statistical water and sediment yield models for a large forested landscape (335,000 ha) on the Kaibab Plateau in northern Arizona, USA. Our objective was to assess the impacts of climate change and forest restoration on the future fire regime, forest vegetation, and watershed outputs. Our model results predict that the combination of climate change and high-severity fire will drive forest turnover, biomass declines, and compositional change in future forests. Restoration treatments may reduce the area burned in high-severity fires and reduce conversions from forested to non-forested conditions. Even though mid-elevation forests are the targets of restoration, the treatments are expected to delay the decline of high-elevation spruce-fir, aspen, and mixed conifer forests by reducing the occurrence of high-severity fires that may spread across ecoregions. We estimate that climate-induced vegetation changes will result in annual runoff declines of up to 10%, while restoration reduced or reversed this decline. The hydrologic model suggests that mid-elevation forests, which are the targets of restoration treatments, provide around 80% of runoff in this system and the conservation of mid- to high-elevation forests types provides the greatest benefit in terms of water conservation. We also predict that restoration treatments will conserve water quality by reducing patches of high-severity fire that are associated with high sediment yield. Restoration treatments are a management strategy that may reduce undesirable outcomes for multiple ecosystem services. © 2018 by the Ecological Society of America.

Spatial characteristics of fire severity in relation to fire growth in a Rocky Mountain subalpine forest

Treesearch

Calvin A. Farris; Ellis Q. Margolis; John A. Kupfer

2008-01-01

We compared the spatial characteristics of fire severity patches within individual fire “runs” (contiguous polygons burned during a given day) resulting from a 72,000 ha fire in centralIdaho in 1994. Our hypothesis was that patch characteristics of four fire severity classes (high, moderate, low, and unburned), as captured by five landscape metrics, would...

Evaluating and monitoring forest fuel treatments using remote sensing applications in Arizona, U.S.A.

USGS Publications Warehouse

Petrakis, Roy; Villarreal, Miguel; Wu, Zhuoting; Hetzler, Robert; Middleton, Barry R.; Norman, Laura M.

2018-01-01

The practice of fire suppression across the western United States over the past century has led to dense forests, and when coupled with drought has contributed to an increase in large and destructive wildfires. Forest management efforts aimed at reducing flammable fuels through various fuel treatments can help to restore frequent fire regimes and increase forest resilience. Our research examines how different fuel treatments influenced burn severity and post-fire vegetative stand dynamics on the San Carlos Apache Reservation, in east-central Arizona, U.S.A. Our methods included the use of multitemporal remote sensing data and cloud computing to evaluate burn severity and post-fire vegetation conditions as well as statistical analyses. We investigated how forest thinning, commercial harvesting, prescribed burning, and resource benefit burning (managed wildfire) related to satellite measured burn severity (the difference Normalized Burn Ratio – dNBR) following the 2013 Creek Fire and used spectral measures of post-fire stand dynamics to track changes in land surface characteristics (i.e., brightness, greenness and wetness). We found strong negative relationships between dNBR and post-fire greenness and wetness, and a positive non-linear relationship between dNBR and brightness, with greater variability at higher severities. Fire severity and post-fire surface changes also differed by treatment type. Our results showed harvested and thinned sites that were not treated with prescribed fire had the highest severity fire. When harvesting was followed by a prescribed burn, the sites experienced lower burn severity and reduced post-fire changes in vegetation greenness and wetness. Areas that had previously experienced resource benefit burns had the lowest burn severities and the highest post-fire greenness measurements compared to all other treatments, except for where the prescribed burn had occurred. These results suggest that fire treatments may be most effective at reducing the probability of hazardous fire and increasing post-fire recovery. This research demonstrates the utility of remote sensing and spatial data to inform forest management, and how various fuel treatments can influence burn severity and post-fire vegetation response within ponderosa pine forests across the southwestern U.S.

Oxygen fires, materials compatibility and system contaminants

NASA Astrophysics Data System (ADS)

Barter, Simon A.; Hillen, Lance W.

An evaluation is made of aircraft fires initiated by oxygen systems, giving attention to such systems' mechanical design and materials-selection factors. While many oxygen compatibility tests are conducted on single components, operational systems become contaminated through frequent use and occasional abuse; it is therefore essential for the designer to have information about the oxygen compatibility of the entire spectrum of potential contaminants and their various combinations. Valve designs are noted to be especially sensitive to system contamination. Gaseous oxygen fire severity is fundamentally determined by the period of oxygen flow. There is a clear need for an automatic shut-off device which would operate when abnormal flow conditions occur.

Effects of fire on ash thickness in a Lithuanian grassland and short-term spatio-temporal changes

NASA Astrophysics Data System (ADS)

Pereira, P.; Cerdà, A.; Úbeda, X.; Mataix-Solera, J.; Martin, D.; Jordán, A.; Burguet, M.

2012-12-01

Ash thickness is a key variable in the protection of soil against erosion agents after planned and unplanned fires. Thicker ash provides better protection against raindrop impact and reduces the runoff response by retaining water and promoting water infiltration although little is known about the distribution and the evolution of the ash layer after the fires. Ash thickness measurements were conducted along two transects (flat and sloping areas) following a a grid experimental design. Both transects extended from the burned area into an adjacent unburned area. We analysed ash thickness evolution according to time and fire severity. In order to interpolate data with accuracy and identify the techniques with the least bias, several interpolation methods were tested in the grid plot. Overall, the fire had a low severity. The fire significantly reduced the ground cover, especially on sloping areas owing to the higher fire severity and/or less biomass previous to the fire. Ash thickness depends on fire severity and is thin where fire severity was higher and thicker in lower fire severity sites. The ash thickness decreased with time after the fire. Between 4 and 16 days after the fire, ash was transported by wind. The major reduction took place between 16 and 34 days after the fire as a result of rainfall, and was more efficient where fire severity was higher. Between 34 and 45 days after the fire no significant differences in ash thickness were identified among ash colours and only traces of the ash layer remained. The omni-directional experimental variograms shown that variable structure did not change importantly with the time, however, the most accurate interpolation methods were different highlighting the slight different patterns of ash thickness distribution with the time. The ash spatial variability increased with the time, particularly on the slope, as a result of water erosion.

The ecology of mixed severity fire regimes in Washington, Oregon, and Northern California

Treesearch

David Perry; Paul Hessburg; Carl Skinner; Thomas Spies; Scott Stephens; Alan Henry Taylor; Jerry Franklin; Brenda McComb; Greg Riegel

2011-01-01

Forests characterized by mixed-severity fires occupy a broad moisture gradient between lower elevation forests typified by low-severity fires and higher elevation forests in which high-severity, stand replacing fires are the norm. Mixed-severity forest types are poorly documented and little understood but likely occupy significant areas in the western United States. By...

Input Source and Strength Influences Overall Firing Phase of Model Hippocampal CA1 Pyramidal Cells During Theta: Relevance to REM Sleep Reactivation and Memory Consolidation

PubMed Central

Booth, Victoria; Poe, Gina R.

2005-01-01

In simulation studies using a realistic model CA1 pyramidal cell, we accounted for the shift in mean firing phase from theta cycle peaks to theta cycle troughs during REM sleep reactivation of hippocampal CA1 place cells over several days of growing familiarization with an environment (Poe et al., 2000). Changes in the theta drive between proximal and distal dendritic regions of the cell modulated the theta phase of firing when stimuli were presented at proximal and distal dendritic locations. Stimuli at proximal dendritic sites (proximal to 100 μm from the soma) invoked firing with a significant phase preference at the depolarizing theta peaks, while distal stimuli (> 290 μm from the soma) invoked firing at hyperpolarizing theta troughs. The location-related phase preference depended on active dendritic conductances, a sufficient electrotonic separation between input sites and theta-induced subthreshold membrane potential oscillations in the cell. The simulation results predict that the shift in mean theta phase during REM sleep cellular reactivation could occur through potentiation of distal dendritic (temporo-ammonic) synapses and depotentiation of proximal dendritic (Schaffer collateral) synapses over the course of familiarization. PMID:16411243

Interactions between atmospheric circulation, nutrient deposition, and tropical forest primary production (Invited)

NASA Astrophysics Data System (ADS)

Randerson, J. T.; Chen, Y.; Rogers, B. M.; Morton, D. C.; van der Werf, G.; Mahowald, N. M.

2010-12-01

Tropical forests influence regional and global climate by means of several pathways, including by modifying surface energy exchange and by forming clouds. High levels of precipitation, leaching, and soil weathering limit nutrient availability in these ecosystems. Phosphorus (P) is a key element limiting net primary production, and in some areas, including forests recovering from prior disturbance, nitrogen (N) also may limit some components of production. Here we quantified atmospheric P and N inputs to these forests from fires using satellite-derived estimates of emissions and atmospheric models. In Africa and South America, cross-biome transport of fire-emitted aerosols and reactive N gases from savannas and areas near the deforestation frontier increased deposition of P and N in interior forests. Equatorward atmospheric transport during the dry (fire) season in one hemisphere was linked with surface winds moving toward the inter-tropical convergence zone (ITCZ) in the other hemisphere. Deposition levels were higher in tropical forests in Africa than in South America because of large savanna areas with high levels of fire emissions in both southern and northern Africa. We conclude by describing a potential feedback loop by which equatorward transport of fire emissions, dust, and spores sustains the productivity of tropical forests. We specifically assessed evidence that savanna-to-forest atmospheric transport of nutrients increases forest productivity, height, and rates of evapotranspiration (ET). In parallel, we examined the degree to which increases in ET and surface roughness in tropical forests have the potential to strengthen several components of the Hadley circulation, including deep convection, equatorward return flow (near the surface), and the intensity of seasonal drought in the subtropics (thereby increasing fires). These interactions are important for understanding biogeochemical - climate interactions on millennial timescales and for quantifying how contemporary changes in fire activity and land use are changing the global carbon cycle.

Catastrophic Fires in Russian Forests

NASA Astrophysics Data System (ADS)

Sukhinin, A. I.; McRae, D. J.; Stocks, B. J.; Conard, S. G.; Hao, W.; Soja, A. J.; Cahoon, D.

2010-12-01

We evaluated the contribution of catastrophic fires to the total burned area and the amount of tree mortality in Russia since the 1970’s. Such fires occurred in the central regions of European Russia (1972, 1976, 1989, 2002, 2010), Khabarovsk krai (1976, 1988, 1998), Amur region (1997-2002), Republics of Yakutia and Tuva (2002), Magadan and Kamchatka oblast (1984, 2001, 2010), and Irkutsk, Chita, Amur regions, Buryat, Agin national districts (2003, 2007-08). We define a catastrophic fire as a single high-severity fire that covers more than 10,000 ha and results in total consumption of the litter and humus layers and in high tree mortality, or the simultaneous occurrence of several high-severity fires in a given region with a total area exceeding 10,000 km2. Fires on this scale can cause substantial economic, social and environmental effects, with regional to global impacts. We hypothesize that there is a positive feedback between anticyclone growth and energy release from wildfires burning over large areas. Usually the first blocking anticyclone appears in June in Russia, bringing with it dry weather that increases fire hazard. The anticyclonic pattern has maximum activity in the end of July and disappears around the middle of August. When high fire activity occurs, the anticyclone may strengthen and develop a blocking character that prevents cyclonic patterns from moving into anticyclone-dominated areas, where the fire danger index may be more than six times the average maximum. The likelihood of uncontrolled fire situations developing increases greatly when the fire number and burned area exceed critical values as a function of conditions that favor high intensity fires. In such situations fire suppression by regional forest protection services becomes impossible and federal resources are required. If the appearance of a blocking anticyclone is forecast, active fire prevention and suppression of small fires (most of which appear to be human caused) is critical. Based on NOAA and TOMS daily data, we estimated fire emissions (including CO2, CO, CH4 and other smoke aerosols) of over 70 Tg Carbon for Yakutian fires in 2002 and more than 120 Tg C for all Russian fires in 2010. We note the potential for increasing amounts of methane emissions when fires occur in permafrost zones and peat bogs. Post-fire changes in permafrost and vegetation cover are discussed in the connection changes in solar radiance balance. During the fire season of 2006 in the Eastern-Siberian, Transbaikal, and Far East regions we identified more than 15,000 fires with a total area of 120,000 km2. From 2002-2010 the annual number of fires in this area ranged from 10,000 to 16,500, and annual burned areas ranged from a low of 30 000 km2 in 2004 to a high of 145,000 km2 in 2003.

Climate-vegetation-fire interactions and their impact on long-term carbon dynamics in a boreal peatland landscape in northern Manitoba, Canada

NASA Astrophysics Data System (ADS)

Camill, Philip; Barry, Ann; Williams, Evie; Andreassi, Christian; Limmer, Jacob; Solick, Donald

2009-12-01

Climate warming may increase the size and frequency of fires in the boreal biome, possibly causing greater carbon release that amplifies warming. However, in peatlands, vegetation change may also control long-term fire and carbon accumulation, confounding simple relationships between climate, fire, and carbon accumulation. Using 17 peat cores dating to 8000 cal years B.P. from northern Manitoba, Canada, we addressed the following questions: (1) Do past climate changes correlate with shifts in peatland vegetation? (2) What is the relationship between peatland vegetation and fire severity? (3) What is the mean return interval for boreal peat fires, and how does it change across fires of different severities? (4) How does fire severity affect carbon accumulation rates? (5) Do fire and long-term carbon accumulation change directly in response to climate or indirectly though climate-driven changes in vegetation? We measured carbon accumulation rates, fire severity, and return intervals using macroscopic charcoal and changes in vegetation using macrofossils. Climate and vegetation changes covaried, with shifts from wetter fen to drier, forested bog communities during the Holocene Thermal Maximum (HTM). Fires became more severe following the shift to forested bogs, with fire severity peaking after 4000 cal years B.P. rather than during the HTM. Rising fire severity, in turn, was correlated with a significant decrease in carbon accumulation from ˜6000 to 2000 cal years B.P. The Medieval Warm Period and Little Ice Age affected vegetation composition and permafrost, further impacting fire and carbon accumulation. Our results indicate that long-term changes in fire and carbon dynamics are mediated by climate-driven changes in vegetation.

Fire behavior, fuel treatments, and fire suppression on the Hayman Fire - Part 4: Relation of roads to burn severity

Treesearch

Charles W. McHugh; Mark A. Finney

2003-01-01

Effects of roads on fire behavior intensity and severity can be studied directly or indirectly. A direct study of road effects would include uses by fire suppression, burnout operations, and delay of fire progress at the roadside. Interpretations after the fire burns are easily confounded by the unknown nature of suppression activities and fire arrival time, and fire...

The impact of post-fire salvage logging on microbial nitrogen cyclers in Mediterranean forest soil.

PubMed

Pereg, Lily; Mataix-Solera, Jorge; McMillan, Mary; García-Orenes, Fuensanta

2018-04-01

Forest fires are a regular occurrence in the Mediterranean basin. High severity fires and post-fire management can affect biological, chemical and physical properties of soil, including the composition and abundance of soil microbial communities. Salvage logging is a post-fire management strategy, which involves the removal of burnt wood from land after a fire. The main objective of this work was to evaluate the impact of post-fire salvage logging and microaggregation on soil microbial communities, specifically on the abundance of nitrogen cyclers and, thus, the potential of the soil for microbial nitrogen cycling. The abundance of nitrogen cyclers was assessed by quantification of microbial nitrogen cycling genes in soil DNA, including nifH (involved in nitrogen fixation), nirS/K and nosZ (involved in denitrification), amoA-B and amoA-Arch (involved in bacterial and archaeal nitrification, respectively). It was demonstrated that salvage logging reduced bacterial load post-fire when compared to tree retention control and resulted in significant changes to the abundance of functional bacteria involved in nitrogen cycling. Microbial gene pools involved in various stages of the nitrogen cycle were larger in control soil than in soil subjected to post-fire salvage logging and were significantly correlated with organic matter, available phosphorous, nitrogen and aggregate stability. The microaggregate fraction of the soil, which has been associated with greater organic carbon, was shown to be a hotspot for nitrogen cyclers particularly under salvage logging. The impact of post-fire management strategies on soil microbial communities needs to be considered in relation to maintaining ecosystem productivity, resilience and potential impact on climate change. Copyright © 2017 Elsevier B.V. All rights reserved.

Modelling and mitigating dose to firefighters from inhalation of radionuclides in wildland fire smoke

DOE PAGES

Viner, Brian J.; Jannik, Tim; Stone, Daniel; ...

2015-06-12

Firefighters responding to wildland fires where surface litter and vegetation contain radiological contamination will receive a radiological dose by inhaling resuspended radioactive material in the smoke. This may increase their lifetime risk of contracting certain types of cancer. Using published data, we modelled hypothetical radionuclide emissions, dispersion and dose for 70th and 97th percentile environmental conditions and for average and high fuel loads at the Savannah River Site. We predicted downwind concentration and potential dose to firefighters for radionuclides of interest ( 137Cs, 238Pu, 90Sr and 210Po). Predicted concentrations exceeded dose guidelines in the base case scenario emissions of 1.0more » × 10 7 Bq ha –1 for 238Pu at 70th percentile environmental conditions and average fuel load levels for both 4- and 14-h shifts. Under 97th percentile environmental conditions and high fuel loads, dose guidelines were exceeded for several reported cases for 90Sr, 238Pu and 210Po. Potential for exceeding dose guidelines was mitigated by including plume rise (>2 m s –1) or moving a small distance from the fire owing to large concentration gradients near the edge of the fire. As a result, our approach can quickly estimate potential dose from airborne radionuclides in wildland fire and assist decision-making to reduce firefighter exposure.« less

Occupational burns from oxygen resuscitator fires: the hazard of aluminum regulators.

PubMed

Hodous, Thomas K; Washenitz, Frank; Newton, Barry

2002-07-01

There have been over 30 incidents of oxygen resuscitator fires over the last 6 years, causing severe burns to a number of fire fighters, emergency medical service personnel, health care workers, and patients. The National Institute for Occupational Safety and Health (NIOSH) was requested to investigate three such incidents. NIOSH conducted site investigations of the incidents, and the requesters also sent the involved oxygen resuscitators to a forensic engineering company for a causal analysis. The investigated fires were associated with aluminum regulators, all from one manufacturer, on compressed pure oxygen cylinders. The investigations indicated that the cause of the fires was an initial small ignition in the high-pressure area of the aluminum regulator, which then consumed itself in a massive burnout. Aluminum regulators used with high-pressure oxygen systems are subject to rare, but potentially catastrophic combustion in normal use. Replacement of such regulators with those made of more fire-resistant materials or designs, as well as education and improved safety practices are needed to reduce this hazard.

Analytical approach to an integrate-and-fire model with spike-triggered adaptation

NASA Astrophysics Data System (ADS)

Schwalger, Tilo; Lindner, Benjamin

2015-12-01

The calculation of the steady-state probability density for multidimensional stochastic systems that do not obey detailed balance is a difficult problem. Here we present the analytical derivation of the stationary joint and various marginal probability densities for a stochastic neuron model with adaptation current. Our approach assumes weak noise but is valid for arbitrary adaptation strength and time scale. The theory predicts several effects of adaptation on the statistics of the membrane potential of a tonically firing neuron: (i) a membrane potential distribution with a convex shape, (ii) a strongly increased probability of hyperpolarized membrane potentials induced by strong and fast adaptation, and (iii) a maximized variability associated with the adaptation current at a finite adaptation time scale.

Who is in the Driver's Seat? Millennial-Scale Records of Wildfire in the Western USA Reveal a Complex Interplay of Climate, Fire, and Vegetation

NASA Astrophysics Data System (ADS)

Pierce, J. L.; Meyer, G. A.; Bigio, E.; Nelson, N.; Poulos, M. J.; Jenkins, S.; Riley, K. E.; Weppner, K.; Svenson, L.; Fitch, E. P.; Frechette, J.

2015-12-01

A new synthesis of 10 study areas and >480 14C dates of Holocene fire and erosional response are recorded in alluvial fan sediments of the interior western US. Chronologies are from high elevation mixed conifer forests in the N. Rockies, ponderosa and Douglas-fir forests in the N. Rockies and SW, and low elevation sagebrush steppe and piñon-juniper woodlands near the Snake River Plain. Results are as follows: 1) Late Holocene arrivals of ponderosa, lodgepole and piñon pine at Northern Rockies sites correspond with increased fire severity, linking vegetation and fire regime changes. 2) Deposit types vary with environment; sheetfloods are more common in sparsely vegetated sites and in drier Holocene periods with open forests, whereas dense forests and infrequent severe fires often produce debris flows. 3) Climate variability drives ponderosa pine and Douglas-fir forests in both the SW and N. Rockies to burn 'at both ends of the spectrum', where frequent low-severity fires are typical, but higher-severity fires burn during severe droughts following fuel buildup over wet decades. 4) Fires in dry sage steppe are generally fuel-limited, but burn during prolonged wet and variable climates; grazing, land-use, and invasive species, particularly influence modern fires. 5) At moist high-elevation lodgepole and mixed conifer sites in Yellowstone and central Idaho, episodic large debris flows indicate high severity burns, often during severe multidecadal droughts. 6) Regionally coherent peaks exist ca. 200, 500, 900, 1700 and 2600 cal yr BP, but fire activity is not generally synchronous among sites. Differences in climate among sites likely account for some asynchroneity. 7) Recent severe fires have burned in 8 of 10 sites described; erosional response appears particularly anomalous in the SW, where impacts of fire suppression and land use are greatest. Widespread and severe modern fires may herald the arrival of a no-analog era of fire in the western US.

The influence of burn severity on post-fire vegetation recovery and albedo change during early succession in North American boreal forests

NASA Astrophysics Data System (ADS)

Jin, Y.; Randerson, J. T.; Goetz, S. J.; Beck, P. S.; Loranty, M. M.; Goulden, M.

2011-12-01

Severity of burning can influence multiple aspects of forest composition, carbon cycling, and climate forcing. We quantified how burn severity affected vegetation recovery and albedo change during early succession in Canadian boreal regions by combining satellite observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Canadian Large Fire Data Base (LFDB). We used the difference Normalized Burn Ratio (dNBR) and changes in spring albedo derived from MODIS 500m albedo product as measures of burn severity. We found that the most severe burns had the greatest reduction in summer EVI in first year after fire, indicating greater loss of vegetation cover immediately following fire. By 5-7 years after fire, summer EVI for all severity classes had recovered to within 90-110% of pre-fire levels. Burn severity had a positive effect on the increase of post-fire spring albedo during the first 7 years after fire, and a shift from low to moderate or moderate to severe fires led to amplification of the post-fire albedo increase by approximately 30%. Fire-induced increases in both spring and summer albedo became progressively larger with stand age from years 1-7, with the trend in spring albedo likely driven by continued losses of needles and branches from trees killed by the fire (and concurrent losses of black carbon coatings on remaining debris), and the summer trend associated with increases in leaf area of short-stature herbs and shrubs. Our results suggest that increases in burn severity and carbon losses observed in some areas of boreal forests (e.g., Turetsky et al., 2011) may be at least partly offset by increases in negative forcing associated with changes in surface albedo.

Israel wildfires: future trends, impacts and mitigation strategies

NASA Astrophysics Data System (ADS)

Wittenberg, Lea

2017-04-01

Forest fires in the Euro-Mediterranean region burn about 450,000 ha each year. In Israel, the frequency and extent of wildfires have been steadily increasing over the past decades, culminating in several large and costly fires in 2010, 2012 and 2016. The extensive development of forest areas since the 1950's and the accumulation of fuel in the forests, has led to increased occurrences of high intensity fires. Land-use changes and human population growth are the most prevailing and common determinant of wildfire occurrence and impacts. Climate extremes, possibly already a sign of regional climate change, are another frequent determinant of increasing wildfire risk. Therefore, the combination of extreme dry spells, high fuel loads and increased anthropogenic pressure on the open spaces result in an overall amplified wildfire risk. These fires not only cause loss of life and damage to properties but also carry serious environmental repercussions. Combustion of standing vegetation and the leaf litter leave the soil bare and vulnerable to runoff and erosion, thereby increasing risks of flooding. Today, all of Israel's open spaces, forests, natural parks, major metropolitan centers, towns and villages are embedded within the wildland urban interface (WUI). Typically, wildfires near or in the WUI occur on uplands and runoff generated from the burned area poses flooding risks in urban and agricultural zones located downstream. Post-fire management aims at reducing associated hazards as collapsing trees and erosion risk. Often the time interval between a major fire and the definition of priority sites is in the order of days-to-weeks since administrative procedures, financial estimates and implementation of post-fire salvage logging operations require time. Defining the magnitude of the burn scar and estimating its potential impact on runoff and erosion must therefore be done quickly. A post-fire burn severity, runoff and erosion model is a useful tool in estimating potential risks and management strategic. Moreover, national agencies and local authorities must decide on a range of post-fire measures to mitigate risks quickly since most large fires occur late in summer shortly before the winter season. Possible climate changes, socio-economic trends, and intense land use pressures are contributing factors in a national challenge to deal with forest fires along the WUI. However, in order to support integrated fire preparedness, response, management and recovery at the national, regional and local scales, stronger research and planning effort are required. This includes long-term monitoring programs and a systematic, standardized data acquisition scheme, compiling fire history, landscape-fire spread, mitigation and assessment of the immediate fire effects, land use changes and weather data. Knowledge of both short and long-term impacts of wildfire is essential for effective risk assessment, policy formulation and wildfire management.

Predicting Fire Season Severity in the Pacific Northwest

Treesearch

Paul Werth

2006-01-01

Projections of fire season severity that integrate historical weather and fire information can be used by fire managers when making decisions about allocating and prioritizing firefighting resources. They enable fire managers to anticipate fire activity and pre-position resources to maximize public and firefighter safety, reduce environmental impacts, and lower...

Barren-ground caribou (Rangifer tarandus groenlandicus) behaviour after recent fire events; integrating caribou telemetry data with Landsat fire detection techniques.

PubMed

Rickbeil, Gregory J M; Hermosilla, Txomin; Coops, Nicholas C; White, Joanne C; Wulder, Michael A

2017-03-01

Fire regimes are changing throughout the North American boreal forest in complex ways. Fire is also a major factor governing access to high-quality forage such as terricholous lichens for barren-ground caribou (Rangifer tarandus groenlandicus). Additionally, fire alters forest structure which can affect barren-ground caribou's ability to navigate in a landscape. Here, we characterize how the size and severity of fires are changing across five barren-ground caribou herd ranges in the Northwest Territories and Nunavut, Canada. Additionally, we demonstrate how time since fire, fire severity, and season result in complex changes in caribou behavioural metrics estimated using telemetry data. Fire disturbances were identified using novel gap-free Landsat surface reflectance composites from 1985 to 2011 across all herd ranges. Burn severity was estimated using the differenced normalized burn ratio. Annual area burned and burn severity were assessed through time for each herd and related to two behavioural metrics: velocity and relative turning angle. Neither annual area burned nor burn severity displayed any temporal trend within the study period. However, certain herds, such as the Ahiak/Beverly, have more exposure to fire than other herds (i.e. Cape Bathurst had a maximum forested area burned of less than 4 km 2 ). Time since fire and burn severity both significantly affected velocity and relative turning angles. During fall, winter, and spring, fire virtually eliminated foraging-focused behaviour for all 26 years of analysis while more severe fires resulted in a marked increase in movement-focused behaviour compared to unburnt patches. Between seasons, caribou used burned areas as early as 1-year postfire, demonstrating complex, nonlinear reactions to time since fire, fire severity, and season. In all cases, increases in movement-focused behaviour were detected postfire. We conclude that changes in caribou behaviour immediately postfire are primarily driven by changes in forest structure rather than changes in terricholous lichen availability. © 2016 John Wiley & Sons Ltd.

The largest forest fires in Portugal: the constraints of burned area size on the comprehension of fire severity.

PubMed

Tedim, Fantina; Remelgado, Ruben; Martins, João; Carvalho, Salete

2015-01-01

Portugal is a European country with highest forest fires density and burned area. Since beginning of official forest fires database in 1980, an increase in number of fires and burned area as well as appearance of large and catastrophic fires have characterized fire activity in Portugal. In 1980s, the largest fires were just a little bit over 10,000 ha. However, in the beginning of 21st century several fires occurred with a burned area over 20,000 ha. Some of these events can be classified as mega-fires due to their ecological and socioeconomic severity. The present study aimed to discuss the characterization of large forest fires trend, in order to understand if the largest fires that occurred in Portugal were exceptional events or evidences of a new trend, and the constraints of fire size to characterize fire effects because, usually, it is assumed that larger the fire higher the damages. Using Portuguese forest fire database and satellite imagery, the present study showed that the largest fires could be seen at the same time as exceptional events and as evidence of a new fire regime. It highlighted the importance of size and patterns of unburned patches within fire perimeter as well as heterogeneity of fire ecological severity, usually not included in fire regime description, which are critical to fire management and research. The findings of this research can be used in forest risk reduction and suppression planning.

How will climate change affect wildland fire severity in the western US?

Treesearch

Sean A. Parks; Carol Miller; John T. Abatzoglou; Lisa M. Holsinger; Marc-Andre Parisien; Solomon Z. Dobrowski

2016-01-01

Fire regime characteristics in North America are expected to change over the next several decades as a result of anthropogenic climate change. Although some fire regime characteristics (e.g., area burned and fire season length) are relatively well-studied in the context of a changing climate, fire severity has received less attention. In this study, we used...

High-severity fire: Evaluating its key drivers and mapping its probability across western US forests

Treesearch

Sean A. Parks; Lisa M. Holsinger; Matthew H. Panunto; W. Matt Jolly; Solomon Z. Dobrowski; Gregory K. Dillon

2018-01-01

Wildland fire is a critical process in forests of the western United States (US). Variation in fire behavior, which is heavily influenced by fuel loading, terrain, weather, and vegetation type, leads to heterogeneity in fire severity across landscapes. The relative influence of these factors in driving fire severity, however, is poorly understood. Here, we explore the...

Fire-severity effects on plant-fungal interactions after a novel tundra wildfire disturbance: implications for arctic shrub and tree migration.

PubMed

Hewitt, Rebecca E; Hollingsworth, Teresa N; Stuart Chapin Iii, F; Lee Taylor, D

2016-05-11

Vegetation change in high latitude tundra ecosystems is expected to accelerate due to increased wildfire activity. High-severity fires increase the availability of mineral soil seedbeds, which facilitates recruitment, yet fire also alters soil microbial composition, which could significantly impact seedling establishment. We investigated the effects of fire severity on soil biota and associated effects on plant performance for two plant species predicted to expand into Arctic tundra. We inoculated seedlings in a growth chamber experiment with soils collected from the largest tundra fire recorded in the Arctic and used molecular tools to characterize root-associated fungal communities. Seedling biomass was significantly related to the composition of fungal inoculum. Biomass decreased as fire severity increased and the proportion of pathogenic fungi increased. Our results suggest that effects of fire severity on soil biota reduces seedling performance and thus we hypothesize that in certain ecological contexts fire-severity effects on plant-fungal interactions may dampen the expected increases in tree and shrub establishment after tundra fire.

Landsat-Based Detection and Severity Analysis of Burned Sugarcane Plots in Tarlac, Philippines Using Differenced Normalized Burn Ratio (dNBR)

NASA Astrophysics Data System (ADS)

Baloloy, A. B.; Blanco, A. C.; Gana, B. S.; Sta. Ana, R. C.; Olalia, L. C.

2016-09-01

The Philippines has a booming sugarcane industry contributing about PHP 70 billion annually to the local economy through raw sugar, molasses and bioethanol production (SRA, 2012). Sugarcane planters adapt different farm practices in cultivating sugarcane, one of which is cane burning to eliminate unwanted plant material and facilitate easier harvest. Information on burned sugarcane extent is significant in yield estimation models to calculate total sugar lost during harvest. Pre-harvest burning can lessen sucrose by 2.7% - 5% of the potential yield (Gomez, et al 2006; Hiranyavasit, 2016). This study employs a method for detecting burn sugarcane area and determining burn severity through Differenced Normalized Burn Ratio (dNBR) using Landsat 8 Images acquired during the late milling season in Tarlac, Philippines. Total burned area was computed per burn severity based on pre-fire and post-fire images. Results show that 75.38% of the total sugarcane fields in Tarlac were burned with post-fire regrowth; 16.61% were recently burned; and only 8.01% were unburned. The monthly dNBR for February to March generated the largest area with low severity burn (1,436 ha) and high severity burn (31.14 ha) due to pre-harvest burning. Post-fire regrowth is highest in April to May when previously burned areas were already replanted with sugarcane. The maximum dNBR of the entire late milling season (February to May) recorded larger extent of areas with high and low post-fire regrowth compared to areas with low, moderate and high burn severity. Normalized Difference Vegetation Index (NDVI) was used to analyse vegetation dynamics between the burn severity classes. Significant positive correlation, rho = 0.99, was observed between dNBR and dNDVI at 5% level (p = 0.004). An accuracy of 89.03% was calculated for the Landsat-derived NBR validated using actual mill data for crop year 2015-2016.

Mixed-severity fire regimes: lessons and hypotheses from the Klamath-Siskiyou ecoregion

Treesearch

J.E. Halofsky; D.C. Donato; D.E. Hibbs; J.L. Campbell; M. Donaghy Cannon; J.B. Fontaine; J.R. Thompson; R.G. Anthony; B.T. Bormann; L.J. Kayes; B.E. Law; D.L. Peterson; T.A. Spies

2011-01-01

Although mixed-severity fires are among the most widespread disturbances influencing western North American forests, they remain the least understood. A major question is the degree to which mixed-severity fire regimes are simply an ecological intermediate between low- and high-severity fire regimes, versus a unique disturbance regime with distinct properties. The...

Is proportion burned severely related to daily area burned?

Treesearch

Donovan S. Birch; Penelope Morgan; Crystal A. Kolden; Andrew T. Hudak; Alistair M. S. Smith

2014-01-01

The ecological effects of forest fires burning with high severity are long-lived and have the greatest impact on vegetation successional trajectories, as compared to low-to-moderate severity fires. The primary drivers of high severity fire are unclear, but it has been hypothesized that wind-driven, large fire-growth days play a significant role, particularly on large...

Temporal and spatial climatic controls on Holocene fire-related erosion and sedimentation, Jemez Mountains, New Mexico

NASA Astrophysics Data System (ADS)

Fitch, Erin P.; Meyer, Grant A.

2016-01-01

In the Jemez Mountains, tree-ring data indicate that low-severity fires characterized the 400 yr before Euro-American settlement, and that subsequent fire suppression promoted denser forests, recent severe fires, and erosion. Over longer timescales, climate change may alter fire regimes; thus, we used fire-related alluvial deposits to assess the timing of moderate- to high-severity fires, their geomorphic impact, and relation to climate over the last 4000 yr. Fire-related sedimentation does not clearly follow millennial-scale climatic changes, but probability peaks commonly correspond with severe drought, e.g., within the interval 1700-1400 cal yr BP, and ca. 650 and ca. 410 cal yr BP. The latter episodes were preceded by prolonged wet intervals that could promote dense stands. Estimated recurrence intervals for fire-related sedimentation are 250-400 yr. Climatic differences with aspect influenced Holocene post-fire response: fire-related deposits constitute 77% of fan sediments from north-facing basins but only 39% of deposits from drier southerly aspects. With sparser vegetation and exposed bedrock, south aspects can generate runoff and sediment when unburned, whereas soil-mantled north aspects produce minor sediment unless severely burned. Recent channel incision appears unprecedented over the last 2300 yr, suggesting that fuel loading and extreme drought produced an anomalously severe burn in 2002.

The development and evaluation of water-mist fire extinguishing systems

NASA Astrophysics Data System (ADS)

Beason, D. G.; Staggs, K. J.

1994-08-01

Fire protection for underfloor space is primarily provided by Halon 1301 which has proven to be very effective. However, due to the link between halons and the possible depletion of the stratospheric ozone layer, plans have been implemented to eventually phase out Halon 1301 and 1211. In September 1987 the Montreal Protocol concerning chlorofluorocarbons (CFC) and halons was signed by the United States, the European Economic Community, and 23 other nations. The Montreal Protocol calls for freezing halon production at 1986 levels. Because the majority of underfloor fire protection at Lawrence Livermore National Laboratory (LLNL), as well as other Department of Energy (DOE) sites, is either Halon 1301 or sprinklers, some other means of suppression will have to be developed and verified. The potential loss to facilities housing computer or control rooms damaged by underfloor fires can be extreme. These losses would not only include hardware and software replacement costs, but also lost computing and control capability. Here at LLNL technical research in a facility could be severely affected. Recent studies conducted by the Fire Research Discipline of the Special Projects Division have shown that severe fires fueled by cable insulation can develop within as little as a 6-in-high underfloor space (even with mechanical ventilation shut off). Studies also show that conventional sprinklers may not be effective in preventing this destruction. Therefore, we are investigating the water-mist fire extinguishing system as an alternative to Halon 1301 and sprinklers.

Climatic stress increases forest fire severity across the western United States

USGS Publications Warehouse

van Mantgem, Philip J.; Nesmith, Jonathan C. B.; Keifer, MaryBeth; Knapp, Eric E.; Flint, Alan; Flint, Lorraine

2013-01-01

Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resulting from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship between climate and fire was present after accounting for fire defences and injuries, and appeared to influence the effects of crown and stem injuries. Climate and fire interactions did not vary substantially across geographical regions, major genera and tree sizes. Our findings support recent physiological evidence showing that both drought and heating from fire can impair xylem conductivity. Warming trends have been linked to increasing probabilities of severe fire weather and fire spread; our results suggest that warming may also increase forest fire severity (the number of trees killed) independent of fire intensity (the amount of heat released during a fire).

Evaluation of weapons' combustion products in armored vehicles. Final report, 30 September 1986-14 December 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menzies, K.T.; Randel, M.A.; Quill, A.L.

1989-01-01

The U.S. Army Biomedical Research and Development Laboratory defined an extensive research program to address the generation of potentially toxic propellant combustion products in crew compartments of armored vehicles during weapons firing. The major objectives of the research were: (1) to determine the presence and concentration of propellant combustion products, (2) to determine potential crew exposure to these combustion products, and (3) to assess the efficacy of field monitoring in armored vehicles. To achieve these goals, air monitoring was conducted in selected armored vehicle types, i.e., M109, M60, M3, M1, at several Army installations. Auxiliary information concerning the specific munitionsmore » fired and the Training and Doctrine Command (TRADOC) or Forces Command (FORSCOM) firing scenarios was collected so that a comparison of pollutant concentrations generated by specific weapons both within vehicle types and between vehicle types could be made.« less

BK channels are required for multisensory plasticity in the oculomotor system

PubMed Central

Nelson, Alexandra; Faulstich, Michael; Moghadam, Setareh; Onori, Kimberly; Meredith, Andrea; du Lac, Sascha

2017-01-01

SUMMARY Neural circuits are endowed with several forms of intrinsic and synaptic plasticity that could contribute to adaptive changes in behavior, but circuit complexities have hindered linking specific cellular mechanisms with their behavioral consequences. Eye movements generated by simple brainstem circuits provide a means for relating cellular plasticity to behavioral gain control. Here we show that firing rate potentiation, a form of intrinsic plasticity mediated by reductions in BK-type calcium activated potassium currents in spontaneously firing neurons, is engaged during optokinetic reflex compensation for inner ear dysfunction. Vestibular loss triggers transient increases in postsynaptic excitability, occlusion of firing rate potentiation, and reductions in BK currents in vestibular nucleus neurons. Concurrently, adaptive increases in visually-evoked eye movements rapidly restore oculomotor function in wildtype mice but are profoundly impaired in BK channel null mice. Activity-dependent regulation of intrinsic excitability may be a general mechanism for adaptive control of behavioral output in multisensory circuits. PMID:27989457

Management and climate contributions to satellite-derived active fire trends in the contiguous United States

PubMed Central

Lin, Hsiao-Wen; McCarty, Jessica L; Wang, Dongdong; Rogers, Brendan M; Morton, Douglas C; Collatz, G James; Jin, Yufang; Randerson, James T

2014-01-01

Fires in croplands, plantations, and rangelands contribute significantly to fire emissions in the United States, yet are often overshadowed by wildland fires in efforts to develop inventories or estimate responses to climate change. Here we quantified decadal trends, interannual variability, and seasonality of Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations of active fires (thermal anomalies) as a function of management type in the contiguous U.S. during 2001–2010. We used the Monitoring Trends in Burn Severity database to identify active fires within the perimeter of large wildland fires and land cover maps to identify active fires in croplands. A third class of fires defined as prescribed/other included all residual satellite active fire detections. Large wildland fires were the most variable of all three fire types and had no significant annual trend in the contiguous U.S. during 2001–2010. Active fires in croplands, in contrast, increased at a rate of 3.4% per year. Cropland and prescribed/other fire types combined were responsible for 77% of the total active fire detections within the U.S and were most abundant in the south and southeast. In the west, cropland active fires decreased at a rate of 5.9% per year, likely in response to intensive air quality policies. Potential evaporation was a dominant regulator of the interannual variability of large wildland fires, but had a weaker influence on the other two fire types. Our analysis suggests it may be possible to modify landscape fire emissions within the U.S. by influencing the way fires are used in managed ecosystems. Key Points Wildland, cropland, and prescribed fires had different trends and patterns Sensitivity to climate varied with fire type Intensity of air quality regulation influenced cropland burning trends PMID:26213662

Management and climate contributions to satellite-derived active fire trends in the contiguous United States.

PubMed

Lin, Hsiao-Wen; McCarty, Jessica L; Wang, Dongdong; Rogers, Brendan M; Morton, Douglas C; Collatz, G James; Jin, Yufang; Randerson, James T

2014-04-01

Fires in croplands, plantations, and rangelands contribute significantly to fire emissions in the United States, yet are often overshadowed by wildland fires in efforts to develop inventories or estimate responses to climate change. Here we quantified decadal trends, interannual variability, and seasonality of Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations of active fires (thermal anomalies) as a function of management type in the contiguous U.S. during 2001-2010. We used the Monitoring Trends in Burn Severity database to identify active fires within the perimeter of large wildland fires and land cover maps to identify active fires in croplands. A third class of fires defined as prescribed/other included all residual satellite active fire detections. Large wildland fires were the most variable of all three fire types and had no significant annual trend in the contiguous U.S. during 2001-2010. Active fires in croplands, in contrast, increased at a rate of 3.4% per year. Cropland and prescribed/other fire types combined were responsible for 77% of the total active fire detections within the U.S and were most abundant in the south and southeast. In the west, cropland active fires decreased at a rate of 5.9% per year, likely in response to intensive air quality policies. Potential evaporation was a dominant regulator of the interannual variability of large wildland fires, but had a weaker influence on the other two fire types. Our analysis suggests it may be possible to modify landscape fire emissions within the U.S. by influencing the way fires are used in managed ecosystems. Wildland, cropland, and prescribed fires had different trends and patternsSensitivity to climate varied with fire typeIntensity of air quality regulation influenced cropland burning trends.

Comparison of six fire severity classification methods using Montana and Washington wildland fires

Treesearch

Pamela G. Sikkink

2015-01-01

Fire severity classifications are used in the post-fire environment to describe fire effects, such as soil alteration or fuel consumption, on the forest floor. Most of the developed classifications are limited because they address very specific fire effects or post-burn characteristics in the burned environment. However, because fire effects vary so much among soil,...

Calibrating a forest landscape model to simulate frequent fire in Mediterranean-type shrublands

USGS Publications Warehouse

Syphard, A.D.; Yang, J.; Franklin, J.; He, H.S.; Keeley, J.E.

2007-01-01

In Mediterranean-type ecosystems (MTEs), fire disturbance influences the distribution of most plant communities, and altered fire regimes may be more important than climate factors in shaping future MTE vegetation dynamics. Models that simulate the high-frequency fire and post-fire response strategies characteristic of these regions will be important tools for evaluating potential landscape change scenarios. However, few existing models have been designed to simulate these properties over long time frames and broad spatial scales. We refined a landscape disturbance and succession (LANDIS) model to operate on an annual time step and to simulate altered fire regimes in a southern California Mediterranean landscape. After developing a comprehensive set of spatial and non-spatial variables and parameters, we calibrated the model to simulate very high fire frequencies and evaluated the simulations under several parameter scenarios representing hypotheses about system dynamics. The goal was to ensure that observed model behavior would simulate the specified fire regime parameters, and that the predictions were reasonable based on current understanding of community dynamics in the region. After calibration, the two dominant plant functional types responded realistically to different fire regime scenarios. Therefore, this model offers a new alternative for simulating altered fire regimes in MTE landscapes. ?? 2007 Elsevier Ltd. All rights reserved.

Tubing Cutter is Activated Hydraulically

NASA Technical Reports Server (NTRS)

Mcsmith, D. G.; Richardson, J. I.

1983-01-01

Hydraulically-actuated tubing cutter severs tubing when operator squeezes handle grip. "Gooseneck" extension enables cutter to be used in areas where accessiblity is limited. Cutter has potential as flight-line tool and is useful in automobile and fire rescue work.

A National Disturbance Modeling System to Support Ecological Carbon Sequestration Assessments

NASA Astrophysics Data System (ADS)

Hawbaker, T. J.; Rollins, M. G.; Volegmann, J. E.; Shi, H.; Sohl, T. L.

2009-12-01

The U.S. Geological Survey (USGS) is prototyping a methodology to fulfill requirements of Section 712 of the Energy Independence and Security Act (EISA) of 2007. At the core of the EISA requirements is the development of a methodology to complete a two-year assessment of current carbon stocks and other greenhouse gas (GHG) fluxes, and potential increases for ecological carbon sequestration under a range of future climate changes, land-use / land-cover configurations, and policy, economic and management scenarios. Disturbances, especially fire, affect vegetation dynamics and ecosystem processes, and can also introduce substantial uncertainty and risk to the efficacy of long-term carbon sequestration strategies. Thus, the potential impacts of disturbances need to be considered under different scenarios. As part of USGS efforts to meet EISA requirements, we developed the National Disturbance Modeling System (NDMS) using a series of statistical and process-based simulation models. NDMS produces spatially-explicit forecasts of future disturbance locations and severity, and the resulting effects on vegetation dynamics. NDMS is embedded within the Forecasting Scenarios of Future Land Cover (FORE-SCE) model and informs the General Ensemble Biogeochemical Modeling System (GEMS) for quantifying carbon stocks and GHG fluxes. For fires, NDMS relies on existing disturbance histories, such as the Landsat derived Monitoring Trends in Burn Severity (MTBS) and Vegetation Change Tracker (VCT) data being used to update LANDFIRE fuels data. The MTBS and VCT data are used to parameterize models predicting the number and size of fires in relation to climate, land-use/land-cover change, and socioeconomic variables. The locations of individual fire ignitions are determined by an ignition probability surface and then FARSITE is used to simulate fire spread in response to weather, fuels, and topography. Following the fire spread simulations, a burn severity model is used to determine annual changes in biomass pools. Vegetation succession among LANDFIRE vegetation types is initiated using burn perimeter and severity data at the end of each annual simulation. Results from NDMS are used to update land-use/land-cover layers used by FORE-SCE and also transferred to GEMS for quantifying and updating carbon stocks and greenhouse gas fluxes. In this presentation, we present: 1) an overview of NDMS and its role in USGS's national ecological carbon sequestration assessment; 2) validation of NDMS using historic data; and 3) initial forecasts of disturbances for the southeastern United States and their impacts on greenhouse gas emissions, and post-fire carbon stocks and fluxes.

Relating fire-caused change in forest structure to remotely sensed estimates of fire severity

Treesearch

Jamie M. Lydersen; Brandon M. Collins; Jay D. Miller; Danny L. Fry; Scott L. Stephens

2016-01-01

Fire severity maps are an important tool for understanding fire effects on a landscape. The relative differenced normalized burn ratio (RdNBR) is a commonly used severity index in California forests, and is typically divided into four categories: unchanged, low, moderate, and high. RdNBR is often calculated twice--from images collected the year of the fire (initial...

Tree mortality based fire severity classification for forest inventories: A Pacific Northwest national forests example

Treesearch

Thomas R. Whittier; Andrew N. Gray

2016-01-01

Determining how the frequency, severity, and extent of forest fires are changing in response to changes in management and climate is a key concern in many regions where fire is an important natural disturbance. In the USA the only national-scale fire severity classification uses satellite image changedetection to produce maps for large (>400 ha) fires, and is...

Interactions among wildland fires in a long-established Sierra Nevada natural fire area

USGS Publications Warehouse

Collins, B.M.; Miller, J.D.; Thode, A.E.; Kelly, M.; van Wagtendonk, J.W.; Stephens, S.L.

2009-01-01

We investigate interactions between successive naturally occurring fires, and assess to what extent the environments in which fires burn influence these interactions. Using mapped fire perimeters and satellite-based estimates of post-fire effects (referred to hereafter as fire severity) for 19 fires burning relatively freely over a 31-year period, we demonstrate that fire as a landscape process can exhibit self-limiting characteristics in an upper elevation Sierra Nevada mixed conifer forest. We use the term 'self-limiting' to refer to recurring fire as a process over time (that is, fire regime) consuming fuel and ultimately constraining the spatial extent and lessening fire-induced effects of subsequent fires. When the amount of time between successive adjacent fires is under 9 years, and when fire weather is not extreme (burning index <34.9), the probability of the latter fire burning into the previous fire area is extremely low. Analysis of fire severity data by 10-year periods revealed a fair degree of stability in the proportion of area burned among fire severity classes (unchanged, low, moderate, high). This is in contrast to a recent study demonstrating increasing high-severity burning throughout the Sierra Nevada from 1984 to 2006, which suggests freely burning fires over time in upper elevation Sierra Nevada mixed conifer forests can regulate fire-induced effects across the landscape. This information can help managers better anticipate short- and long-term effects of allowing naturally ignited fires to burn, and ultimately, improve their ability to implement Wildland Fire Use programs in similar forest types. ?? 2008 Springer Science+Business Media, LLC.

Resilience of Mediterranean terrestrial ecosystems and fire severity in semiarid areas: Responses of Aleppo pine forests in the short, mid and long term.

PubMed

González-De Vega, S; De Las Heras, J; Moya, D

2016-12-15

In recent decades, the fire regime of the Mediterranean Basin has been disturbed by various factors: climate change; forest management policies; land cover; changed landscape. Size and severity have notably increased, which in turn have increased large fires events with >500ha burned (high severity). In spite of Mediterranean ecosystems' high resilience to fire, these changes have implied more vulnerability and reduced natural recovery with irreparable long-term negative effects. Knowledge of the response of ecosystems to increasing severity, mainly in semiarid areas, is still lacking, which is needed to rehabilitate and restore burned areas. Our approach assessed the resilience concept by focusing on the recovery of ecosystem functions and services, measured as changes in the composition and diversity of plant community vegetation and structure. This will be validated in the long term as a model of ecosystem response. Also, depending on the pre-fire characteristics of vegetation, fire severity and the post-fire management, this approach will lead to tools that can be applied to implement post-fire restoration efforts in order to help decision making in planning activities. Regarding Mediterranean ecosystems' ability to recover after wildfires, this study concludes that pre-fire communities are resilient in these fire-prone areas, but the window for natural recovery in semiarid areas of Aleppo pine forest in SE Iberian Peninsula varied from 3 to 15 post-fire years. Fire severity was also key for effects on the ecosystem: the vegetation types of areas burned with low and medium severity recovered naturally, while those areas with a high-severity burn induced shrublands. We concluded that very strong regeneration activity exists in the short term, and that the negative effects of medium- and high-severity fire are evidenced in the mid and long term, which affect natural recovery. Adaptive forest management to rehabilitate and restore burned Mediterranean ecosystems should be implemented. Copyright © 2016 Elsevier B.V. All rights reserved.

Potentials and limitations of remote fire monitoring in protected areas.

PubMed

Dos Santos, João Flávio Costa; Romeiro, Joyce Machado Nunes; de Assis, José Batuíra; Torres, Fillipe Tamiozzo Pereira; Gleriani, José Marinaldo

2018-03-01

Protected areas (PAs) play an important role in maintaining the biodiversity and ecological processes of the site. One of the greatest challenges for the PA management in several biomes in the world is wildfires. The objective of this work was to evaluate the potentialities and limitations of the use of data obtained by orbital remote sensing in the monitoring fire occurrence in PAs. Fire Occurrence Records (FORs) were analyzed in Serra do Brigadeiro State Park, Minas Gerais, Brazil, from 2007 to 2015, using photo interpreted data from TM, ETM + and OLI sensors of the Landsat series and the Hot Spot Database (HSD) from the Brazilian Institute of Space Research - INPE. It was also observed the time of permanence of the scar left by fire on the landscape, through the multitemporal analysis of the behavior of NDVI (Normalized Difference Vegetation Index) and NBR (Normalized Burn Ratio) indexes, before and after the occurrence. The greatest limitation found for the orbital remote monitoring was the presence of clouds in the passage of the sensor in dates close to the occurrence of the fires. The burned area identified by photo interpretation was 54.9% less than the area contained in the FOR. Although the HSD reported fire occurrences in the buffer zone (up to 10km from the Park), no FORs were found at a distance greater than 1100m from the boundaries of the PA. As the main potential of remote sensing, the possibility of identifying burned areas throughout the park and surroundings is highlighted, with low costs and greater accuracy. Copyright © 2017 Elsevier B.V. All rights reserved.

Remote sensing of fire severity: linking post-fire reflectance data with physiological responses in two western conifer species

NASA Astrophysics Data System (ADS)

Sparks, A. M.; Smith, A. M.; Kolden, C.; Apostol, K. G.; Boschetti, L.

2014-12-01

Fire is a common disturbance in forested ecosystems in the western U.S. and can be responsible for long-term impacts on vegetation and soil. An improved understanding of how ecosystems recover after fire is necessary so that land managers can plan for and mitigate the effects of these disturbances. Although several studies have attempted to link fire intensity with severity, direct links between spectral indices of severity and key physiological changes in vegetation are not well understood. We conducted an assessment of how two western conifer species respond to four fire radiative energy treatments, with spectra acquired pre- and up to a month post-burn. After transforming the spectral data into Landsat 8 equivalent reflectance, burn severity indices commonly used in the remote sensing community were compared to concurrent physiological measurements including gas exchange and photosynthetic rate. Preliminary results indicate significant relationships between several fire severity indices and physiological responses measured in the conifer seedlings.

Bat Response to Differing Fire Severity in Mixed-Conifer Forest California, USA

PubMed Central

Heady, Paul A.; Hayes, John P.; Frick, Winifred F.

2013-01-01

Wildlife response to natural disturbances such as fire is of conservation concern to managers, policy makers, and scientists, yet information is scant beyond a few well-studied groups (e.g., birds, small mammals). We examined the effects of wildfire severity on bats, a taxon of high conservation concern, at both the stand (<1 ha) and landscape scale in response to the 2002 McNally fire in the Sierra Nevada region of California, USA. One year after fire, we conducted surveys of echolocation activity at 14 survey locations, stratified in riparian and upland habitat, in mixed-conifer forest habitats spanning three levels of burn severity: unburned, moderate, and high. Bat activity in burned areas was either equivalent or higher than in unburned stands for all six phonic groups measured, with four groups having significantly greater activity in at least one burn severity level. Evidence of differentiation between fire severities was observed with some Myotis species having higher levels of activity in stands of high-severity burn. Larger-bodied bats, typically adapted to more open habitat, showed no response to fire. We found differential use of riparian and upland habitats among the phonic groups, yet no interaction of habitat type by fire severity was found. Extent of high-severity fire damage in the landscape had no effect on activity of bats in unburned sites suggesting no landscape effect of fire on foraging site selection and emphasizing stand-scale conditions driving bat activity. Results from this fire in mixed-conifer forests of California suggest that bats are resilient to landscape-scale fire and that some species are preferentially selecting burned areas for foraging, perhaps facilitated by reduced clutter and increased post-fire availability of prey and roosts. PMID:23483936

Activity-Dependent Changes in the Firing Properties of Neocortical Fast-Spiking Interneurons in the Absence of Large Changes in Gene Expression

PubMed Central

Miller, Mark N.; Okaty, Benjamin W.; Kato, Saori; Nelson, Sacha B.

2010-01-01

The diverse cell types that comprise neocortical circuits each have characteristic integrative and firing properties that are specialized to perform specific functions within the network. Parvalbumin-positive fast-spiking (FS) interneurons are a particularly specialized cortical cell-type that controls the dynamics of ongoing activity and prevents runaway excitation by virtue of remarkably high firing rates, a feature that is permitted by narrow action potentials and the absence of spike-frequency adaptation. Although several neuronal intrinsic membrane properties undergo activity-dependent plasticity, the role of network activity in shaping and maintaining specialized, cell-type-specific firing properties is unknown. We tested whether the specialized firing properties of mature FS interneurons are sensitive to activity perturbations by inactivating a portion of motor cortex in vivo for 48 hours and measuring resulting plasticity of FS intrinsic and firing properties with whole-cell recording in acute slices. Many of the characteristic properties of FS interneurons, including non-adapting high-frequency spiking and narrow action potentials, were profoundly affected by activity deprivation both at an age just after maturation of FS firing properties and also a week after their maturation. Using microarray screening, we determined that although normal maturation of FS electrophysiological specializations is accompanied by large-scale transcriptional changes, the effects of deprivation on the same specializations involve more modest transcriptional changes, and may instead be primarily mediated by post-transcriptional mechanisms. PMID:21154910

Fuel models and fire potential from satellite and surface observations

USGS Publications Warehouse

Burgan, R.E.; Klaver, R.W.; Klarer, J.M.

1998-01-01

A national 1-km resolution fire danger fuel model map was derived through use of previously mapped land cover classes and ecoregions, and extensive ground sample data, then refined through review by fire managers familiar with various portions of the U.S. The fuel model map will be used in the next generation fire danger rating system for the U.S., but it also made possible immediate development of a satellite and ground based fire potential index map. The inputs and algorithm of the fire potential index are presented, along with a case study of the correlation between the fire potential index and fire occurrence in California and Nevada. Application of the fire potential index in the Mediterranean ecosystems of Spain, Chile, and Mexico will be tested.

Prevention of Surgical Fires: A Certification Course for Healthcare Providers.

PubMed

Fisher, Marquessa

2015-08-01

An estimated 550 to 650 surgical fires occur annually in the United States. Surgical fires may have severe consequences, including burns, disfigurement, long-term medical care, or death. This article introduces a potential certification program for the prevention of surgical fires. A pilot study was conducted with a convenience sample of 10 anesthesia providers who participated in the education module. The overall objective was to educate surgical team members and to prepare them to become certified in surgical fire prevention. On completion of the education module, participants completed the 50-question certification examination. The mean pretest score was 66%; none of the participants had enough correct responses (85%) to be considered competent in surgical fire prevention. The mean post- test score was 92.80%, with all participants answering at least 85% of questions correct. A paired-samples t test showed a statistically significant increase in knowledge: t (df = 9) = 11.40; P = .001. Results of the pilot study indicate that this course can remediate gaps in knowledge of surgical fire prevention for providers. Their poor performance on the pretest suggests that many providers may not receive sufficient instruction in surgical fire prevention.

Large-Scale Forest Fires and Resulting Alterations to the Hydrologic Cycle in the Western U.S

NASA Astrophysics Data System (ADS)

Carr, J.; White, A. B.; Thomson, B.

2012-12-01

Recent changes in climate have resulted in a decrease in precipitation and snowpack amounts and increased temperatures in the western United States. Drier and warmer conditions coupled with forest management issues have led to an increase in the frequency and size of forest fires. The 2000 Cerro Grande fire in Los Alamos, New Mexico burned over 43,000 acres and 200 structures. Eleven years later, the Las Conchas fire burned over 156,000 acres and 100 structures, including areas previously burned in 2000, and was considered the largest fire in New Mexico's history. Both fires burned ponderosa, juniper, piñon and mixed conifer forests, resulting in dramatic decreases in vegetation, changes to surface soils, and alterations to the hydrologic cycle (decreased evapotranspiration, decreased infiltration, increased runoff volume and peak discharge, and decreased time to peak discharge) in surrounding watersheds. Burned Area Emergency Response (BAER) teams need to determine the flash-flood danger quickly in order to protect residents, fire-fighters, BAER-team field personnel, and property at risk. The USGS developed an analytical method for predicting post-fire peak discharges using data collected from eight different fires throughout the western United States. We use this method to predict peak discharge in Los Alamos watersheds post-Cerro Grande and post-Las Conchas, then compare predicted to measured peak discharge. We will evaluate the effectiveness of the three methodology levels presented by the USGS, which include varying levels of data input and processing. We expect the peak discharges to be similar in magnitude; however, we will also investigate different influential factors such as burn severity, soil type, vegetation type and density, ecological connectivity, topography, pre- and post-fire weather conditions, etc., as they relate to the fires and the results seen from the measured versus the analytical method. Determining the relative influence of these factors may be important in establishing the comprehensive nature of the methodology. The frequency of large, intense "mega-fires" are predicted to increase, thus there is a potential for more post-fire flood damage and more surface water resources to be altered due to water quality issues. For example, the Whitewater-Baldy Complex fire became the largest fire in New Mexico's history one year after the Las Conchas fire by burning almost 300,000 acres in the Gila National Forest in southern New Mexico, the Little Bear fire in 2012 forced the closure of Alto Reservoir for the foreseeable future due to ash and debris, and the Las Conchas fire forced several surface water treatment facilities serving Santa Fe and Albuquerque to shut down. As these fires become more frequent, there is a potential that less surface water will be available and more groundwater will be pumped for human and agricultural use in the western U.S., where water scarcity is already a pressing problem. Understanding how these fires alter the hydrologic cycle is critical to water policy and planning and this research will help advance that understanding.

Shrub-Steppe Early Succession Following Juniper Cutting and Prescribed Fire

NASA Astrophysics Data System (ADS)

Bates, Jonathan D.; Davies, Kirk W.; Sharp, Robert N.

2011-03-01

Pinus- Juniperus L. (Piñon-juniper) woodlands of the western United States have expanded in area nearly 10-fold since the late 1800's. Juniperus occidentalis ssp. occidentalis Hook. (western juniper) dominance in sagebrush steppe has several negative consequences, including reductions in herbaceous production and diversity, decreased wildlife habitat, and higher erosion and runoff potentials. Prescribed fire and mechanical tree removal are the main methods used to control J. occidentalis and restore sagebrush steppe. However, mature woodlands become difficult to prescribe burn because of the lack of understory fuels. We evaluated partial cutting of the woodlands (cutting 25-50% of the trees) to increase surface fuels, followed by prescribed fire treatments in late successional J. occidentalis woodlands of southwest Idaho to assess understory recovery. The study was conducted in two different plant associations and evaluated what percentage of the woodland required preparatory cutting to eliminate remaining J. occidentalis by prescribed fire, determined the impacts of fire to understory species, and examined early post-fire successional dynamics. The study demonstrated that late successional J. occidentalis woodlands can be burned after pre-cutting only a portion of the trees. Early succession in the cut-and-burn treatments were dominated by native annual and perennial forbs, in part due to high mortality of perennial bunchgrasses. By the third year after fire the number of establishing perennial grass seedlings indicated that both associations would achieve full herbaceous recovery. Cutting-prescribed fire combinations are an effective means for controlling encroaching late successional J. occidentalis and restoring herbaceous plant communities. However, land managers should recognize that there are potential problems associated with cutting-prescribed fire applications when invasive weeds are present.

Shrub-steppe early succession following juniper cutting and prescribed fire.

PubMed

Bates, Jonathan D; Davies, Kirk W; Sharp, Robert N

2011-03-01

Pinus-Juniperus L. (Piñon-juniper) woodlands of the western United States have expanded in area nearly 10-fold since the late 1800's. Juniperus occidentalis ssp. occidentalis Hook. (western juniper) dominance in sagebrush steppe has several negative consequences, including reductions in herbaceous production and diversity, decreased wildlife habitat, and higher erosion and runoff potentials. Prescribed fire and mechanical tree removal are the main methods used to control J. occidentalis and restore sagebrush steppe. However, mature woodlands become difficult to prescribe burn because of the lack of understory fuels. We evaluated partial cutting of the woodlands (cutting 25-50% of the trees) to increase surface fuels, followed by prescribed fire treatments in late successional J. occidentalis woodlands of southwest Idaho to assess understory recovery. The study was conducted in two different plant associations and evaluated what percentage of the woodland required preparatory cutting to eliminate remaining J. occidentalis by prescribed fire, determined the impacts of fire to understory species, and examined early post-fire successional dynamics. The study demonstrated that late successional J. occidentalis woodlands can be burned after pre-cutting only a portion of the trees. Early succession in the cut-and-burn treatments were dominated by native annual and perennial forbs, in part due to high mortality of perennial bunchgrasses. By the third year after fire the number of establishing perennial grass seedlings indicated that both associations would achieve full herbaceous recovery. Cutting-prescribed fire combinations are an effective means for controlling encroaching late successional J. occidentalis and restoring herbaceous plant communities. However, land managers should recognize that there are potential problems associated with cutting-prescribed fire applications when invasive weeds are present.

A new field method to characterise the runoff generation potential of burned hillslopes

NASA Astrophysics Data System (ADS)

Sheridan, Gary; Lane, Patrick; Langhans, Christoph

2016-04-01

The prediction of post fire runoff generation is critical for the estimation of post fire erosion processes and rates. Typical field measures for determining infiltration model parameters include ring infiltrometers, tension infiltrometers, rainfall simulators and natural runoff plots. However predicting the runoff generating potential of post-fire hillslopes is difficult due to the high spatial variability of soil properties relative to the size of the measurement method, the poorly understood relationship between water repellence and runoff generation, known scaling issues with all the above hydraulic measurements, and logistical limitations for measurements in remote environments. In this study we tested a new field method for characterizing surface runoff generation potential that overcomes these limitations and is quick, simple and cheap to apply in the field. The new field method involves the manual application of a 40mm depth of Brilliant Blue FCF food dye along a 10cm wide and 5m long transect along the contour under slightly-ponded conditions. After 24 hours the transect is excavated to a depth of 10cm and the percentage dyed area within the soil profile recorded manually. The dyed area is an index of infiltration potential of the soil during intense rainfall events, and captures both spatial variability and water repellence effects. The dye measurements were made adjacent to long term instrumented post fire rainfall-runoff plots on 7 contrasting soil types over a 6 month period, and the results show surprisingly strong correlations (r2 = 0.9) between the runoff-ratio from the plots and the dyed area. The results are used to develop an initial conceptual model that links the dye index with an infiltration model and parameters suited to burnt hillslopes. The capacity of this method to provide a simple, and reliable indicator of post fire runoff potential from different fire severities, soil types and treatments is explored in this presentation.

Impact of a moderate/high-severity prescribed eucalypt forest fire on soil phosphorous stocks and partitioning.

PubMed

Santín, Cristina; Otero, Xose L; Doerr, Stefan H; Chafer, Chris J

2018-04-15

This study examines the direct impact of a moderate/high-severity prescribed fire on phosphorous (P) stocks and partitioning in oligotrophic soils of a dry eucalypt forest within Sydney's water supply catchments, Australia. We also quantify and characterize the P present in the ash produced in this fire, and explore its relationships with the maximum temperatures recorded in the litter layer during the burn. In these oligotrophic soils, P concentrations were already relatively low before the fire (<130mgkg -1 , mainly in organic forms). The fire consumed the entire litter layer and the thin Oa soil horizon, creating 6.3±3.1tha -1 of ash, and resulted into direct net P losses of ~7kgha -1 . The P lost was mostly organic and there was a moderate net gain of inorganic and non-reactive P forms. Importantly, only a small proportion of the post-fire P was bioavailable (equivalent to ~3% of the total P lost during fire). Higher total P concentrations in ash corresponded with higher maximum temperatures (>650°C) recorded in the burning litter layer, but effects of fire temperature on ash P partitioning were not significant. Fire not only transformed P chemically, but also physically. Our results show that, immediately after fire, up to 2kgha -1 of P was present in the ash layer and, therefore, highly erodible and susceptible to be transported off-site by wind- and water erosion. Even if most of this P was, initially, of low bioavailability, its transfer to depositional environments with different geochemical conditions (e.g. anoxic sediments in water reservoirs) can alter its geochemical forms and availability. Further investigation of potential P transformations off-site is therefore essential, particularly given that SE-Australian water supply catchments are subject to recurrent perturbation by prescribed fire and wildfires. The latter have already resulted in major algal blooms in water supply reservoirs. Copyright © 2017 Elsevier B.V. All rights reserved.

Vegetation and topographical correlates of fire severity from two fires in the Klamath-Siskiyou region of Oregon and California

Treesearch

John D. Alexander; Nathaniel E. Seavy; C Ralph; Bill Hogoboom

2006-01-01

We used vegetation data collected in areas before they were burned by the 2500 ha Quartz fire in southern Oregon and the 50 600 ha Big Bar complex in northern California to evaluate the ability of vegetation and topographic characteristics to predict patterns of fire severity. Fire severity was characterized as high, moderate, or low based on crown scorch and...

Mixed severity fire effects within the Rim fire: Relative importance of local climate, fire weather, topography, and forest structure

Treesearch

Van R. Kane; C. Alina Cansler; Nicholas A. Povak; Jonathan T. Kane; Robert J. McGaughey; James A. Lutz; Derek J. Churchill; Malcolm P. North

2015-01-01

Recent and projected increases in the frequency and severity of large wildfires in the western U.S. makes understanding the factors that strongly affect landscape fire patterns a management priority for optimizing treatment location. We compared the influence of variations in the local environment on burn severity patterns on the large 2013 Rim fire that burned under...

Tongue-tied: Confused meanings for common fire terminology can lead to fuels mismanagement

Treesearch

Theresa B. Jain; Russell T. Graham; David S. Pilliod

2004-01-01

The ineffective and inconsistent use of terminology among fire managers, scientists, resource managers and the public is a constant problem in resource management. In fire management and fire science, the terms fire severity, burn severity and fire intensity are defined in a variety of ways, used inconsistently and, in some cases, interchangeably.

Using RAQMS Chemical Transport Model, Aircraft In-situ and Satellite Data to Verify Ground-based Biomass Burning Emissions from the Extreme Fire Event in Boreal Alaska 2004

NASA Astrophysics Data System (ADS)

Soja, A. J.; Pierce, R. B.; Al-Saadi, J. A.; Alvarado, E.; Sandberg, D. V.; Ottmar, R. D.; Kittaka, C.; McMillian, W. W.; Sachse, G. W.; Warner, J. X.; Szykman, J. J.

2006-12-01

Current climate change scenarios are predicted to result in increased biomass burning, particularly in boreal regions. Biomass burning events feedback to the climate system by altering albedo (affecting the energy balance) and by direct and indirect fire emissions. Additionally, fire emissions influence air quality and human health downwind of burning. Biomass burning emission estimates are difficult to quantify in near-real-time and accurate estimates are useful for large-scale chemical transport models, which could be used to warn the public of potential health risks and for climate modeling. In this talk, we describe a methodology to quantify emissions, validate those emission estimates, transport the emissions and verify the resultant CO plume 100's of kilometers from the fire events using aircraft in-situ and satellite data. First, we developed carbon consumption estimates that are specifically designed for near-real-time use in conjunction with satellite-derived fire data for regional- to global-chemical transport models. Large-scale carbon consumption estimates are derived for 10 ecozones across North America and each zone contains 3 classes of severity. The estimates range is from a low severity 3.11 t C ha-1 estimate from the Western Taiga Shield to a high severity 59.83 t C ha-1 estimate from the Boreal Cordillera. These estimates are validated using extensive supplementary ground-based Alaskan data. Then, the RAQMS chemical transport model ingests these data and transports CO from the Alaskan 2004 fires across North America, where results are compared with in-situ flight CO data measured during INTEX-A and satellite-based CO data (AIRS and MOPITT). Ground-based CO is 6 to 14 times greater than the typically modeled fire climatology. RAQMS often overestimates CO in the biomass plumes in comparison to satellite- derived CO data and we suspect this may be due to the satellite instruments low sensitivity to planetary boundary layer CO, which is prevalent in the near field plumes, and also the assumption of high-severity fires throughout the burning season. RAQMS underestimates biomass CO in comparison to in-situ CO data (146 out of 148 ascents and descents), and we suspect this may be due to RAQMS difficulty in defining narrow fire plumes due to the 1.4° x 1.4° resolution.

Quantifying soil burn severity for hydrologic modeling to assess post-fire effects on sediment delivery

NASA Astrophysics Data System (ADS)

Dobre, Mariana; Brooks, Erin; Lew, Roger; Kolden, Crystal; Quinn, Dylan; Elliot, William; Robichaud, Pete

2017-04-01

Soil erosion is a secondary fire effect with great implications for many ecosystem resources. Depending on the burn severity, topography, and the weather immediately after the fire, soil erosion can impact municipal water supplies, degrade water quality, and reduce reservoirs' storage capacity. Scientists and managers use field and remotely sensed data to quickly assess post-fire burn severity in ecologically-sensitive areas. From these assessments, mitigation activities are implemented to minimize post-fire flood and soil erosion and to facilitate post-fire vegetation recovery. Alternatively, land managers can use fire behavior and spread models (e.g. FlamMap, FARSITE, FOFEM, or CONSUME) to identify sensitive areas a priori, and apply strategies such as fuel reduction treatments to proactively minimize the risk of wildfire spread and increased burn severity. There is a growing interest in linking fire behavior and spread models with hydrology-based soil erosion models to provide site-specific assessment of mitigation treatments on post-fire runoff and erosion. The challenge remains, however, that many burn severity mapping and modeling products quantify vegetation loss rather than measuring soil burn severity. Wildfire burn severity is spatially heterogeneous and depends on the pre-fire vegetation cover, fuel load, topography, and weather. Severities also differ depending on the variable of interest (e.g. soil, vegetation). In the United States, Burned Area Reflectance Classification (BARC) maps, derived from Landsat satellite images, are used as an initial burn severity assessment. BARC maps are classified from either a Normalized Burn Ratio (NBR) or differenced Normalized Burned Ratio (dNBR) scene into four classes (Unburned, Low, Moderate, and High severity). The development of soil burn severity maps requires further manual field validation efforts to transform the BARC maps into a product more applicable for post-fire soil rehabilitation activities. Alternative spectral indices and modeled output approaches may prove better predictors of soil burn severity and hydrologic effects, but these have not yet been assessed in a model framework. In this project we compare field-verified soil burn severity maps to satellite-derived and modeled burn severity maps. We quantify the extent to which there are systematic differences in these mapping products. We then use the Water Erosion Prediction Project (WEPP) hydrologic soil erosion model to assess sediment delivery from these fires using the predicted and observed soil burn severity maps. Finally, we discuss differences in observed and predicted soil burn severity maps and application to watersheds in the Pacific Northwest to estimate post-fire sediment delivery.

Fire ignition during laser surgery in pet rodents

PubMed Central

2012-01-01

Background Laser surgery is an attractive alternative to other means of section device in terms of tissue inflammation and interaction, which has been extensively used in human and veterinary medicine. Although accidental ignition during laser surgeries is sporadically reported in human medical literature, to the authors’ knowledge this is the first report regarding laser-dependent fire ignition during surgery in veterinary medicine. Case presentation Two rodents, a 13-month old, 27-gram, male pet mouse (Mus musculus) and a 1-year old, female Russian hamster (Phodopus sungorus), underwent surgical removal of masses with diode laser. During the surgical procedures fires ignited from the face masks. The mouse presented severe burns on the head and both forelimbs, it was hospitalized and approximately 2 months after surgery burns were resolved. The hamster presented severe burns on the face and the proximal regions of the body. At 72 hours from the accident the hamster was euthanized. Conclusion The present report suggests that fire ignition is a potential life-threatening complication of laser surgery in non-intubated rodents maintained under volatile anesthesia. High oxygen concentrations, the presence of combustible, and the narrowness of the surgical field with the face mask during laser surgery on rodents are risk factors for fire ignition. PMID:23009047

Temporal characterisation of soil-plant natural recovery related to fire severity in burned Pinus halepensis Mill. forests.

PubMed

Moya, D; González-De Vega, S; García-Orenes, F; Morugán-Coronado, A; Arcenegui, V; Mataix-Solera, J; Lucas-Borja, M E; De Las Heras, J

2018-05-28

Despite Mediterranean ecosystems' high resilience to fire, both climate and land use change, and alterations in fire regimes increase their vulnerability to fire by affecting the long-term natural recovery of ecosystem services. The objective of this work is to study the effects of fire severity on biochemical soil indicators, such as chemical composition or enzymatic activity, related to time after fire and natural vegetation recovery (soil-plant interphase). Soil samples from three wildfires occurring 3, 15 and 21 years ago were taken in the south-eastern Iberian Peninsula (semiarid climate). Sampling included three fire severity levels in naturally regenerated (and changing to shrublands) Pinus halepensis Mill. forests. In the short-term post-fire period, phosphorus concentration, electrical conductivity and urease activity were positively linked to fire severity, and also influenced β-glucosidade activity in a negative relationship. During the 15-21-year post-fire period, the effects related to medium-high fire severity were negligible and soil quality indicators were linked to natural regeneration success. The results showed that most soil properties recovered in the long term after fire (21 years). These outcomes will help managers and stakeholders to implement management tools to stabilise soils and to restore burned ecosystems affected by medium-high fire severity. Such knowledge can be considered in adaptive forest management to reduce the negative effects of wildfires and desertification, and to improve the resilience of vulnerable ecosystems in a global change scenario. Copyright © 2018 Elsevier B.V. All rights reserved.

The Big Burn: C Emissions from the Northern Rockies 1910 Fires

NASA Astrophysics Data System (ADS)

Walsh, E.; Hudiburg, T. W.

2017-12-01

The forest fires in August of 1910 were one of the greatest fire events in modern U.S. history. The Big Burn of northern Idaho and northwest Montana overwhelmed the burgeoning U.S. Forest Service suppression efforts and would ultimately harden the policy of fire suppression in the United States that prevails today. The fire burned 12k km2 (approximately the size of Connecticut) in two days with an estimated loss of 8 billion board feet of timber valued at $329 million (2016 dollars). Though one of the greatest natural events in U.S. history, little research has focused on the effect of the fires on CO2 emissions and forest successional pathways of this region. Based on fire extents and timber mortality reports, we estimate the fire resulted in 11 Mg/ha in dead woody biomass and potentially as much as 52 Tg C (191 Tg CO2) released as direct emissions. This is 58%-116% above the average yearly direct carbon emissions due to fire during 2002-2012 in the CONUS. We modeled the subsequent fires and change in species composition providing a measure of the observed shift from white pine (Pinus monticola), western larch (Larix occidentalis) and fir (Abies spp.) to lodgepole pine (Pinus contorta). These models can provide biogeochemical and forest successional pathway context for future changes in forest composition and fire severity/extent due to climate change.

Using the Large Fire Simulator System to map wildland fire potential for the conterminous United States

Treesearch

LaWen Hollingsworth; James Menakis

2010-01-01

This project mapped wildland fire potential (WFP) for the conterminous United States by using the large fire simulation system developed for Fire Program Analysis (FPA) System. The large fire simulation system, referred to here as LFSim, consists of modules for weather generation, fire occurrence, fire suppression, and fire growth modeling. Weather was generated with...

The role of fire severity, distance from fire perimeter and vegetation on post-fire recovery of small-mammal communities in chaparal

Treesearch

Jay Diffendorfer; Genie M. Fleming; Scott Tremor; Wayne Spencer; Jan L. Beyers

2012-01-01

Chaparral shrublands in southern California, US, exhibit significant biodiversity but are prone to large, intense wildfires. Debate exists regarding fuel reduction to prevent such fires in wildland areas, but the effects of these fires on fauna are not well understood. We studied whether fire severity and distance from unburned fire perimeter influenced recovery of the...

Ecological effects of large fires on US landscapes: benefit or catastrophe?

USGS Publications Warehouse

Keane, Robert E.; Agee, James K.; Fule, Peter; Keeley, Jon E.; Key, Carl H.; Kitchen, Stanley G.; Miller, Richard; Schulte, Lisa A.

2008-01-01

The perception is that today’s large fires are an ecological catastrophe because they burn vast areas with high intensities and severities. However, little is known of the ecological impacts of large fires on both historical and contemporary landscapes. The present paper presents a review of the current knowledge of the effects of large fires in the United States by important ecosystems written by regional experts. The ecosystems are (1) ponderosa pine–Douglas-fir, (2) sagebrush–grasslands, (3) piñon–juniper, (4) chaparral, (5) mixed-conifer, and (6) spruce–fir. This review found that large fires were common on most historical western US landscapes and they will continue to be common today with exceptions. Sagebrush ecosystems are currently experiencing larger, more severe, and more frequent large fires compared to historical conditions due to exotic cheatgrass invasions. Historical large fires in south-west ponderosa pine forest created a mixed severity mosaic dominated by non-lethal surface fires while today’s large fires are mostly high severity crown fires. While large fires play an important role in landscape ecology for most regions, their importance is much less in the dry piñon–juniper forests and sagebrush–grasslands. Fire management must address the role of large fires in maintaining the health of many US fire-dominated ecosystems.

Fire-induced Carbon Emissions and Regrowth Uptake in Western U.S. Forests: Documenting Variation Across Forest Types, Fire Severity, and Climate Regions

NASA Technical Reports Server (NTRS)

Ghimire, Bardan; Williams, Christopher A.; Collatz, George James; Vanderhoof, Melanie

2012-01-01

The forest area in the western United States that burns annually is increasing with warmer temperatures, more frequent droughts, and higher fuel densities. Studies that examine fire effects for regional carbon balances have tended to either focus on individual fires as examples or adopt generalizations without considering how forest type, fire severity, and regional climate influence carbon legacies. This study provides a more detailed characterization of fire effects and quantifies the full carbon impacts in relation to direct emissions, slow release of fire-killed biomass, and net carbon uptake from forest regrowth. We find important variations in fire-induced mortality and combustion across carbon pools (leaf, live wood, dead wood, litter, and duff) and across low- to high-severity classes. This corresponds to fire-induced direct emissions from 1984 to 2008 averaging 4 TgC/yr and biomass killed averaging 10.5 TgC/yr, with average burn area of 2723 sq km/yr across the western United States. These direct emission and biomass killed rates were 1.4 and 3.7 times higher, respectively, for high-severity fires than those for low-severity fires. The results show that forest regrowth varies greatly by forest type and with severity and that these factors impose a sustained carbon uptake legacy. The western U.S. fires between 1984 and 2008 imposed a net source of 12.3 TgC/yr in 2008, accounting for both direct fire emissions (9.5 TgC/yr) and heterotrophic decomposition of fire-killed biomass (6.1 TgC yr1) as well as contemporary regrowth sinks (3.3 TgC/yr). A sizeable trend exists toward increasing emissions as a larger area burns annually.

Social validation and training of emergency fire safety skills for potential injury prevention and life saving.

PubMed Central

Jones, R T; Kazdin, A E; Haney, J I

1981-01-01

A multifaceted behavioral program designed to teach emergency fire escape procedures to children was evaluated in a multiple-baseline design. Five children were trained to respond correctly to nine home emergency fire situations under simulated conditions. The situations and responses focused upon in training were identified by a social validation procedure involving consultation with several safety agencies, including the direct input of firefighters. Training, carried out in simulated bedrooms at school, resulted in significant improvements in both overt behavior and self-report of fire safety skills. The gains were maintained at a post-check assessment 2 weeks after training had been terminated. The results are discussed in relation both to the importance of social validation of targets and outcomes and the implications for further research in assessing and developing emergency response skills. PMID:7298537

Climatic stress increases forest fire severity across the western United States.

PubMed

van Mantgem, Phillip J; Nesmith, Jonathan C B; Keifer, MaryBeth; Knapp, Eric E; Flint, Alan; Flint, Lorriane

2013-09-01

Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resulting from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship between climate and fire was present after accounting for fire defences and injuries, and appeared to influence the effects of crown and stem injuries. Climate and fire interactions did not vary substantially across geographical regions, major genera and tree sizes. Our findings support recent physiological evidence showing that both drought and heating from fire can impair xylem conductivity. Warming trends have been linked to increasing probabilities of severe fire weather and fire spread; our results suggest that warming may also increase forest fire severity (the number of trees killed) independent of fire intensity (the amount of heat released during a fire). Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viner, Brian J.; Jannik, Tim; Stone, Daniel

Firefighters responding to wildland fires where surface litter and vegetation contain radiological contamination will receive a radiological dose by inhaling resuspended radioactive material in the smoke. This may increase their lifetime risk of contracting certain types of cancer. Using published data, we modelled hypothetical radionuclide emissions, dispersion and dose for 70th and 97th percentile environmental conditions and for average and high fuel loads at the Savannah River Site. We predicted downwind concentration and potential dose to firefighters for radionuclides of interest ( 137Cs, 238Pu, 90Sr and 210Po). Predicted concentrations exceeded dose guidelines in the base case scenario emissions of 1.0more » × 10 7 Bq ha –1 for 238Pu at 70th percentile environmental conditions and average fuel load levels for both 4- and 14-h shifts. Under 97th percentile environmental conditions and high fuel loads, dose guidelines were exceeded for several reported cases for 90Sr, 238Pu and 210Po. Potential for exceeding dose guidelines was mitigated by including plume rise (>2 m s –1) or moving a small distance from the fire owing to large concentration gradients near the edge of the fire. As a result, our approach can quickly estimate potential dose from airborne radionuclides in wildland fire and assist decision-making to reduce firefighter exposure.« less

Permafrost as an additional driving factor for the extreme fire event in the boreal Baikal region in 2003

NASA Astrophysics Data System (ADS)

Forkel, M.; Thonicke, K.; Beer, C.; Cramer, W.; Bartalev, S.; Schmullius, C.

2012-04-01

Wildfires are a natural and important element in the functioning of boreal forests. However, in some years, fires with extreme spread and severity occur. Such severe fires degrade the forest, affect human values, emit huge amount of carbon and aerosols and alter the land surface albedo. Usually, wind, slope, and dry conditions have been recognized as factors determining fire spread. In the Baikal region, 127,000 km2 burned in 2003, while the annual average burned area is approx. 8100 km2. In average years, 16% of the burned area occurred in the continuous permafrost zone but in 2003, 33% of these burned areas coincide with the existence of permanently frozen grounds. Permafrost and the associated upper active layer, which thaws during summer and refreezes during winter, is an important supply for soil moisture in boreal ecosystems. This leads to the question if permafrost hydrology is a potential additional driving factor for extreme fire events in boreal forests. Using temperature and precipitation data, we calculated the Nesterov index as indicator for fire weather conditions. Further, we used satellite observations of burned area and surface moisture, a digital elevation model, a land cover and a permafrost map to evaluate drivers for the temporal dynamic and spatial variability of surface moisture conditions and burned area in spring 2003. On the basis of time series decomposition, we separated the effect of drivers for fire activity on different time scales. We next computed cross-correlations to identify potential time lags between weather conditions, surface moisture and fire activity. Finally, we assessed the predictive capability of different combinations of driving variables for surface moisture conditions and burned area using multivariate spatial-temporal regression models. The results from this study demonstrate that permafrost in larch-dominated ecosystems regulates the inter-annual variability of surface moisture and thus increases the inter-annual variability of burned area. The drought conditions in spring 2003 were accelerated by the presence of permafrost because less water was stored in the upper active layer from the dry previous summer 2002 and the permafrost table prevents vegetative water uptake from deeper layers. In contrast, weather conditions (precipitation anomaly, Nesterov index) are weaker predictors for the 2003 fire event. Our analysis advances the understanding of complex interactions between the atmosphere, vegetation and soil on how feedback mechanisms can lead to extreme fire events. These findings emphasize the importance of a mechanistic coupling of soil thermodynamics, hydrology, and fire activity in earth system models for projecting climate change impacts over the next century.

Fire modeling in the Brazilian arc of deforestation through nested coupling of atmosphere, dynamic vegetation, LUCC and fire spread models

NASA Astrophysics Data System (ADS)

Tourigny, E.; Nobre, C.; Cardoso, M. F.

2012-12-01

Deforestation of tropical forests for logging and agriculture, associated to slash-and-burn practices, is a major source of CO2 emissions, both immediate due to biomass burning and future due to the elimination of a potential CO2 sink. Feedbacks between climate change and LUCC (Land-Use and Land-Cover Change) can potentially increase the loss of tropical forests and increase the rate of CO2 emissions, through mechanisms such as land and soil degradation and the increase in wildfire occurrence and severity. However, current understanding of the processes of fires (including ignition, spread and consequences) in tropical forests and climatic feedbacks are poorly understood and need further research. As the processes of LUCC and associated fires occur at local scales, linking them to large-scale atmospheric processes requires a means of up-scaling higher resolutions processes to lower resolutions. Our approach is to couple models which operate at various spatial and temporal scales: a Global Climate Model (GCM), Dynamic Global Vegetation Model (DGVM) and local-scale LUCC and fire spread model. The climate model resolves large scale atmospheric processes and forcings, which are imposed on the surface DGVM and fed-back to climate. Higher-resolution processes such as deforestation, land use management and associated (as well as natural) fires are resolved at the local level. A dynamic tiling scheme allows to represent local-scale heterogeneity while maintaining computational efficiency of the land surface model, compared to traditional landscape models. Fire behavior is modeled at the regional scale (~500m) to represent the detailed landscape using a semi-empirical fire spread model. The relatively coarse scale (as compared to other fire spread models) is necessary due to the paucity of detailed land-cover information and fire history (particularly in the tropics and developing countries). This work presents initial results of a spatially-explicit fire spread model coupled to the IBIS DGVM model. Our area of study comprises selected regions in and near the Brazilian "arc of deforestation". For model training and evaluation, several areas have been mapped using high-resolution imagery from the Landsat TM/ETM+ sensors (Figure 1). This high resolution reference data is used for local-scale simulations and also to evaluate the accuracy of the global MCD45 burned area product, which will be used in future studies covering the entire "arc of deforestation".; Area of study along the arc of deforestation and cerrado: landsat scenes used and burned area (2010) from MCD45 product.

Resilience Through Disturbance: Effects of Wildfire on Vegetation and Water Balance in the Sierra Nevadas

NASA Astrophysics Data System (ADS)

Boisrame, G. F. S.; Thompson, S. E.; Stephens, S.; Collins, B.; Tague, N.

2015-12-01

A century of fire suppression in the Western United States has drastically altered the historically fire-adapated ecology in California's Sierra Nevada Mountains. Fire suppression is understood to have increased the forest cover, as well as the stem density, canopy cover and water demand of montane forests, reducing resilience of the forests to drought, and increasing the risk of catastrophic fire by drying the landscape and increasing fuel loads. The potential to reverse these trends by re-introducing fire into the Sierra Nevada is highly promising, but the likely effects on vegetation structure and water balance are poorly quantified. The Illilouette Creek Basin in Yosemite National Park represents a unique experiment in the Sierra Nevada, in which managers have moved from fire suppression to allowing a near-natural fire regime to prevail since 1972. Changes in vegetation structure in the Illilouette since the restoration of natural burning provides a unique opportunity to examine how frequent, mixed severity fires can reshape the Sierra Nevada landscape. We characterize these changes from 1969 to the present using a combination of Landsat products and high-resolution aerial imagery. We describe how the landscape structure has changed in terms of vegetation composition and its spatial organization, and explore the drivers of different post-fire vegetation type transitions (e.g. forest to shrubland vs. forest to meadow). By upscaling field data using vegetation maps and Landsat wetness indices, we explore how these vegetation transitions have impacted the water balance of the Illilouette Creek Basin, potentially increasing its resilience in the face of drought, climate change, and catastrophic fire. In a region that is adapted to frequent disturbance from fire, this work helps us understand how allowing such natural disturbances to take place can increase the sustainability of diverse landscapes in the long term.

Prescribed fire and its impacts on ecosystem services in the UK.

PubMed

Harper, Ashleigh R; Doerr, Stefan H; Santin, Cristina; Froyd, Cynthia A; Sinnadurai, Paul

2018-05-15

The impacts of vegetation fires on ecosystems are complex and varied affecting a range of important ecosystem services. Fire has the potential to affect the physicochemical and ecological status of water systems, alter several aspects of the carbon cycle (e.g. above- and below-ground carbon storage) and trigger changes in vegetation type and structure. Globally, fire is an essential part of land management in fire-prone regions in, e.g. Australia, the USA and some Mediterranean countries to mitigate the likelihood of catastrophic wildfires and sustain healthy ecosystems. In the less-fire prone UK, fire has a long history of usage in management for enhancing the productivity of heather, red grouse and sheep. This distinctly different socioeconomic tradition of burning underlies some of the controversy in recent decades in the UK around the use of fire. Negative public opinion and opposition from popular media have highlighted concerns around the detrimental impacts burning can have on the health and diversity of upland habitats. It is evident there are many gaps in the current knowledge around the environmental impacts of prescribed burning in less fire-prone regions (e.g. UK). Land owners and managers require a greater level of certainty on the advantages and disadvantages of prescribed burning in comparison to other techniques to better inform management practices. This paper addresses this gap by providing a critical review of published work and future research directions related to the impacts of prescribed fire on three key aspects of ecosystem services: (i) water quality, (ii) carbon dynamics and (iii) habitat composition and structure (biodiversity). Its overall aims are to provide guidance based on the current state-of-the-art for researchers, land owners, managers and policy makers on the potential effects of the use of burning and to inform the wider debate about the place of fire in modern conservation and land management in humid temperate ecosystems. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Post-fire regeneration across a fire severity gradient in the southern Cascades

Treesearch

Justin Crotteau; Morgan Varner; Martin Ritchie

2012-01-01

Large scale, high-severity fires are increasing in the western United States. Despite this trend, there have been few studies investigating post-fire tree regeneration. We established a study in the footprint of the 2000 Storrie Fire, a 23,000 ha wildfire that occurred in northern California, USA. We used a stratified sampling design to quantify post-fire vegetation...

The ecological importance of mixed-severity fires: Nature's phoenix [Book Review

Treesearch

Carolyn H. Sieg

2016-01-01

The stated goal of a recent book, The Ecological Importance of Mixed-Severity Fires: Nature’s Phoenix, edited by Dominick A. DellaSala and Chad T. Hansen, is to provide a global reference on the benefits of mixed- and high-severity fires. Note that the goal is not to provide an objective reference on the ecological aspects of mixed- and high-severity fires. Rather, the...

Fire Effects on Microbial Dynamics and C, N, and P Cycling in Larch Forests of the Siberian Arctic

NASA Astrophysics Data System (ADS)

Ludwig, S.; Alexander, H. D.; Mann, P. J.; Natali, S.; Schade, J. D.

2013-12-01

Arctic forest ecosystems are warming at an accelerated rate relative to lower latitudes, with global implications for C cycling within these regions. As climate continues to warm and dry, wildfire frequency and severity are predicted to increase, creating a positive feedback to climate warming. Because soil microbes regulate carbon (C) and nitrogen (N) cycling between terrestrial ecosystems and the atmosphere, it is important to understand microbial response to fires, particularly in the understudied larch forests in the Siberian Arctic. In this project, we created experimental burn plots in a mature larch forest in the Kolyma River watershed of Northeastern Siberia. Plots were burned at several treatments: control (no burn), low, moderate, and severe. After 1 day, 8 days and 1 year post-fire, we measured CO2 flux from the plots, and measured dissolved organic carbon (DOC), total dissolved nitrogen (TDN), NH4, NO3, PO4, and chromophoric dissolved organic matter (CDOM) from soil leachates. Furthermore, we measured extracellular activity of four enzymes involved in soil C and nutrient cycling (leucine aminopeptidase (LAP), β-glucosidase, phosphatase, and phenol oxidase). Both 1 day and 8 days post-fire DOC, TDN, NH4, and PO4 all increased with burn severity, but by 1 year they were similar to control plots. The aromaticity and molecular weight of DOM decreased with fire severity. One day post-fire we observed a spike in phenol oxidase activity in the severe burns only, and a decline in β-glucosidase and phosphatase activity. By 8 days post-fire all enzyme activities were at the level of the control plots. 1 year post-fire LAP, β-glucosidase, and phosphatase all decreased with fire severity, parallel to a decrease in CO2 flux by fire severity. Ratios of enzymatic activity 1 year post-fire reflect a switch of resource allocation from P acquiring to N acquiring activities in more severe fires. Our results show an immediate microbial response to the short-term effects of fire severity that reflects both a change in nutrient use and the form and concentration of C being processed, and a response to long-term effects of fire severity that show further changes in nutrient use and overall decreased microbial activity. These findings highlight the importance of changing fire regimes on soil dynamics with implications for forest re-growth, soil-atmospheric feedbacks, and terrestrial inputs to aquatic ecosystems.

Fuel moisture - a guide for evaluating severity of fire seasons

Treesearch

Richard J. Barney

1964-01-01

Field personnel in all forest fire protection agencies need some simple but reasonably accurate method for evaluating severity of the fire season as it progresses and of comparing severity of the current season with that of preceding fire seasons. This paper proposes use of records of average fuel moisture percentages cumulated continuously for 5-day periods throughout...

Mapping and exploring variation in post-fire vegetation recovery following mixed severity wildfire using airborne LiDAR.

PubMed

Gordon, Christopher E; Price, Owen F; Tasker, Elizabeth M

2017-07-01

There is a public perception that large high-severity wildfires decrease biodiversity and increase fire hazard by homogenizing vegetation composition and increasing the cover of mid-story vegetation. But a growing literature suggests that vegetation responses are nuanced. LiDAR technology provides a promising remote sensing tool to test hypotheses about post-fire vegetation regrowth because vegetation cover can be quantified within different height strata at fine scales over large areas. We assess the usefulness of airborne LiDAR data for measuring post-fire mid-story vegetation regrowth over a range of spatial resolutions (10 × 10 m, 30 × 30 m, 50 × 50 m, 100 × 100 m cell size) and investigate the effect of fire severity on regrowth amount and spatial pattern following a mixed severity wildfire in Warrumbungle National Park, Australia. We predicted that recovery would be more vigorous in areas of high fire severity, because park managers observed dense post-fire regrowth in these areas. Moderate to strong positive associations were observed between LiDAR and field surveys of mid-story vegetation cover between 0.5-3.0 m. Thus our LiDAR survey was an apt representation of on-ground vegetation cover. LiDAR-derived mid-story vegetation cover was 22-40% lower in areas of low and moderate than high fire severity. Linear mixed-effects models showed that fire severity was among the strongest biophysical predictors of mid-story vegetation cover irrespective of spatial resolution. However much of the variance associated with these models was unexplained, presumably because soil seed banks varied at finer scales than our LiDAR maps. Dense patches of mid-story vegetation regrowth were small (median size 0.01 ha) and evenly distributed between areas of low, moderate and high fire severity, demonstrating that high-severity fires do not homogenize vegetation cover. Our results are relevant for ecosystem conservation and fire management because they: indicate that native vegetation are responsive and resilient to high-severity fire, and show the usefulness of remote sensing tools such as LiDAR to monitor post-fire vegetation recovery over large areas in situ. © 2017 by the Ecological Society of America.

Reduced frequency and severity of residential fires following delivery of fire prevention education by on-duty fire fighters: cluster randomized controlled study.

PubMed

Clare, Joseph; Garis, Len; Plecas, Darryl; Jennings, Charles

2012-04-01

In 2008, Surrey Fire Services, British Columbia, commenced a firefighter-delivered, door-to-door fire-prevention education and smoke alarm examination/installation initiative with the intention of reducing the frequency and severity of residential structure fires in the City of Surrey. High-risk zones within the city were identified and 18,473 home visits were undertaken across seven temporal delivery cohorts (13.8% of non-apartment dwellings in the city). The frequency and severity of fires pre- and post- the home visit intervention was examined in comparison to randomized high-risk cluster controls. Overall, the frequency of fires was found to have reduced in the city overall, however, the reduction in the intervention cohorts was significantly larger than for controls. Furthermore, when fires did occur within the intervention cohorts, smoke detectors were activated more frequently and the fires were confined to the object of origin more often post-home visits. No equivalent pattern was observed for the cluster control. On-duty fire fighters can reduce the frequency and severity of residential fires through targeted, door-to-door distribution of fire prevention education in high-risk areas. Copyright © 2012 Elsevier Ltd. All rights reserved.

Areas of Agreement and Disagreement Regarding Ponderosa Pine and Mixed Conifer Forest Fire Regimes: A Dialogue with Stevens et al.

PubMed Central

Odion, Dennis C.; Hanson, Chad T.; Baker, William L.; DellaSala, Dominick A.; Williams, Mark A.

2016-01-01

In a recent PLOS ONE paper, we conducted an evidence-based analysis of current versus historical fire regimes and concluded that traditionally defined reference conditions of low-severity fire regimes for ponderosa pine (Pinus ponderosa) and mixed-conifer forests were incomplete, missing considerable variability in forest structure and fire regimes. Stevens et al. (this issue) agree that high-severity fire was a component of these forests, but disagree that one of the several sources of evidence, stand age from a large number of forest inventory and analysis (FIA) plots across the western USA, support our findings that severe fire played more than a minor role ecologically in these forests. Here we highlight areas of agreement and disagreement about past fire, and analyze the methods Stevens et al. used to assess the FIA stand-age data. We found a major problem with a calculation they used to conclude that the FIA data were not useful for evaluating fire regimes. Their calculation, as well as a narrowing of the definition of high-severity fire from the one we used, leads to a large underestimate of conditions consistent with historical high-severity fire. The FIA stand age data do have limitations but they are consistent with other landscape-inference data sources in supporting a broader paradigm about historical variability of fire in ponderosa and mixed-conifer forests than had been traditionally recognized, as described in our previous PLOS paper. PMID:27195808

Areas of Agreement and Disagreement Regarding Ponderosa Pine and Mixed Conifer Forest Fire Regimes: A Dialogue with Stevens et al.

PubMed

Odion, Dennis C; Hanson, Chad T; Baker, William L; DellaSala, Dominick A; Williams, Mark A

2016-01-01

In a recent PLOS ONE paper, we conducted an evidence-based analysis of current versus historical fire regimes and concluded that traditionally defined reference conditions of low-severity fire regimes for ponderosa pine (Pinus ponderosa) and mixed-conifer forests were incomplete, missing considerable variability in forest structure and fire regimes. Stevens et al. (this issue) agree that high-severity fire was a component of these forests, but disagree that one of the several sources of evidence, stand age from a large number of forest inventory and analysis (FIA) plots across the western USA, support our findings that severe fire played more than a minor role ecologically in these forests. Here we highlight areas of agreement and disagreement about past fire, and analyze the methods Stevens et al. used to assess the FIA stand-age data. We found a major problem with a calculation they used to conclude that the FIA data were not useful for evaluating fire regimes. Their calculation, as well as a narrowing of the definition of high-severity fire from the one we used, leads to a large underestimate of conditions consistent with historical high-severity fire. The FIA stand age data do have limitations but they are consistent with other landscape-inference data sources in supporting a broader paradigm about historical variability of fire in ponderosa and mixed-conifer forests than had been traditionally recognized, as described in our previous PLOS paper.

Potential climate change impacts on fire intensity and key wildfire suppression thresholds in Canada

NASA Astrophysics Data System (ADS)

Wotton, B. M.; Flannigan, M. D.; Marshall, G. A.

2017-09-01

Much research has been carried out on the potential impacts of climate change on forest fire activity in the boreal forest. Indeed, there is a general consensus that, while change will vary regionally across the vast extent of the boreal, in general the fire environment will become more conducive to fire. Land management agencies must consider ways to adapt to these new conditions. This paper examines the impact of that changed fire environment on overall wildfire suppression capability. We use multiple General Circulation Models and carbon emission pathways to generate future fire environment scenarios for Canada’s forested region. We then use these scenarios with the Canadian Forest Fire Behaviour Prediction System and spatial coverages of the current forest fuel composition across the landscape to examine potential variation in key fire behaviour outputs that influence whether fire management resources can effectively suppress fire. Specifically, we evaluate how the potential for crown fire occurrence and active growth of fires changes with the changing climate. We also examine future fire behaviour through the lens of operational fire intensity thresholds used to guide decisions about resources effectiveness. Results indicate that the proportion of days in fire seasons with the potential for unmanageable fire will increase across Canada’s forest, more than doubling in some regions in northern and eastern boreal forest.

Borneo on Fire

Atmospheric Science Data Center

2016-12-23

... the land surface, meaning it had the potential to affect air quality not only locally but as far as 1,000 miles (1,600 kilometers) away in Malaysia. For several weeks, episodes of hazardous pollution from the heavy smoke have been causing emergency school closures and ...

Geographic Mapping as a Tool for Identifying Communities at High Risk for Fires.

PubMed

Fahey, Erin; Lehna, Carlee; Hanchette, Carol; Coty, Mary-Beth

2016-01-01

The purpose of this study was to evaluate whether the sample of older adults in a home fire safety (HFS) study captured participants living in the areas at highest risk for fire occurrence. The secondary aim was to identify high risk areas to focus future HFS interventions. Geographic information systems software was used to identify census tracts where study participants resided. Census data for these tracts were compared with participant data based on seven risk factors (ie, age greater than 65 years, nonwhite race, below high school education, low socioeconomic status, rented housing, year home built, home value) previously identified in a fire risk model. The distribution of participants and census tracts among risk categories determined how well higher risk census tracts were sampled. Of the 46 census tracts where the HFS intervention was implemented, 78% (n = 36) were identified as high or severe risk according to the fire risk model. Study participants' means for median annual family income (P < .0001) and median home value (P < .0001) were significantly lower than the census tract means (n = 46), indicating participants were at higher risk of fire occurrence. Of the 92 census tracts identified as high or severe risk in the entire county, the study intervention was implemented in 39% (n = 36), indicating 56 census tracts as potential areas for future HFS interventions. The Geographic information system-based fire risk model is an underutilized but important tool for practice that allows community agencies to develop, plan, and evaluate their outreach efforts and ensure the most effective use of scarce resources.

Monitoring Soil Erosion on a Burned Site in the Mojave-Great Basin Transition Zone: Final Report for the Jacob Fire Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Julianne; Etyemezian, Vic; Cablk, Mary E.

A historic return interval of 100 years for large fires in the U.S. southwestern deserts is being replaced by one where fires may reoccur as frequently as every 20 to 30 years. The shortened return interval, which translates to an increase in fires, has implications for management of Soil Corrective Action Units (CAUs) and Corrective Action Sites (CASs) for which the Department of Energy, National Nuclear Security Administration Nevada Field Office has responsibility. A series of studies was initiated at uncontaminated analog sites to better understand the possible impacts of erosion and transport by wind and water should contaminated soilmore » sites burn. The first of these studies was undertaken at the Jacob Fire site approximately 12 kilometers (7.5 miles) north of Hiko, Nevada. A lightning-caused fire burned approximately 200 hectares during August 6-8, 2008. The site is representative of a transition between Mojave and Great Basin desert ecoregions on the Nevada National Security Site (NNSS), where the largest number of Soil CAUs/CASs are located. The area that burned at the Jacob Fire site was primarily a Coleogyne ramosissima (blackbrush) and Ephedra nevadensis (Mormon tea) community, also an abundant shrub assemblage in the similar transition zone on the NNSS. This report summarizes three years of measurements after the fire. Seven measurement campaigns at the Jacob Fire site were completed. Measurements were made on burned ridge (upland) and drainage sites, and on burned and unburned sites beneath and between vegetation. A Portable In-Situ Wind Erosion Lab (PI-SWERL) was used to estimate emissions of suspended particles at different wind speeds. Context for these measurements was provided through a meteorological tower that was installed at the Jacob Fire site to obtain local, relevant environmental parameters. Filter samples, collected from the exhaust of the PI-SWERL during measurements, were analyzed for chemical composition. Runoff and water erosion were quantified through a series of rainfall/runoff simulation tests in which controlled amounts of water were delivered to the soil surface in a specified amount of time. Runoff data were collected from understory and interspace soils on burned ridge and drainage areas. Runoff volume and suspended sediment in the runoff were sampled; the particle size distribution of the sediment was determined by laboratory analysis. Several land surface and soil characteristics associated with runoff were integrated by the calculation of site-specific curve numbers. Several vegetation surveys were conducted to assess post-burn recovery. Data from plots in both burned and unburned areas included species identification, counts, and location. Characterization of fire-affected area included measures at both the landscape scale and at specific sites. Although wind erosion measurements indicate that there are seasonal influences on almost all parameters measured, several trends were observed. PI-SWERL measurements indicated the potential for PM10 windblown dust emissions was higher on areas that were burned compared to areas that were not. Among the burned areas, understory soils in drainage areas were the most emissive, and interspace soils along burned ridges were least emissive. By 34 months after the burn (MAB), at the end of the study, emissions from all burned soil sites were virtually indistinguishable from unburned levels. Like the amount of emissions, the chemical signature of the fire (indicated by the EC-Soil ratio) was elevated immediately after the fire and approached pre-burn levels by 24 MAB. Thus, the potential for wind erosion at the Jacob Fire site, as measured by the amount and type of emissions, increased significantly after the fire and returned to unburned levels by 24 MAB. The effect of fire on the potential for water erosion at the Jacob Fire site was more ambiguous. Runoff and sediment from ridge interspace soils and unburned interspace soils were similar throughout the study period. Seldom, if ever, did runoff and sediment occur in burned drainage area soils. For burned soils where runoff occurred at 1 MAB, the sediment size was finer than on unburned sites, but this effect disappeared by 3 MAB. For the three year study under the conditions tested at the Jacob Fire site, the potential for water erosion appeared relatively unaffected by the fire. Vegetation responses were documented for each year following the fire. By the end of the study, there was a substantial difference in plant densities and richness between drainage and ridge sites. Cheatgrass densities were higher in unburned plots, and cheatgrass was also more dominant in the community composition in unburned plots. Cheatgrass had increased in the burned area but so did other native species. Three years after the fire, the burned landscape continued to revegetate but had yet to approximate the condition of an unburned landscape. The results from the vegetation surveys support the wind erosion results, where the primary source of windborne particles originate from the understory, where lower plant diversity and densities were found. The soil appears to be more resilient and have a much shorter recovery time than the vegetation in this particular community.« less

Avifaunal responses to fire in southwestern montane forests along a burn severity gradient

USGS Publications Warehouse

Kotliar, N.B.; Kennedy, P.L.; Ferree, K.

2007-01-01

The effects of burn severity on avian communities are poorly understood, yet this information is crucial to fire management programs. To quantify avian response patterns along a burn severity gradient, we sampled 49 random plots (2001-2002) at the 17 351-ha Cerro Grande Fire (2000) in New Mexico, USA. Additionally, pre-fire avian surveys (1986-1988, 1990) created a unique opportunity to quantify avifaunal changes in 13 pre-fire transects (resampled in 2002) and to compare two designs for analyzing the effects of unplanned disturbances: after-only analysis and before-after comparisons. Distance analysis was used to calculate densities. We analyzed after-only densities for 21 species using gradient analysis, which detected a broad range of responses to increasing burn severity: (I) large significant declines, (II) weak, but significant declines, (III) no significant density changes, (IV) peak densities in low- or moderate-severity patches, (V) weak, but significant increases, and (VI) large significant increases. Overall, 71% of the species included in the after-only gradient analysis exhibited either positive or neutral density responses to fire effects across all or portions of the severity gradient (responses III-VI). We used pre/post pairs analysis to quantify density changes for 15 species using before-after comparisons; spatiotemporal variation in densities was large and confounded fire effects for most species. Only four species demonstrated significant effects of burn severity, and their densities were all higher in burned compared to unburned forests. Pre- and post-fire community similarity was high except in high-severity areas. Species richness was similar pre- and post-fire across all burn severities. Thus, ecosystem restoration programs based on the assumption that recent severe fires in Southwestern ponderosa pine forests have overriding negative ecological effects are not supported by our study of post-fire avian communities. This study illustrates the importance of quantifying burn severity and controlling confounding sources of spatiotemporal variation in studies of fire effects. After-only gradient analysis can be an efficient tool for quantifying fire effects. This analysis can also augment historical data sets that have small samples sizes coupled with high non-process variation, which limits the power of before-after comparisons. ?? 2007 by the Ecological Society of America.

Fish Mercury Loads and Lake Productivity Are Not Impacted by Wildland Fire in Northern Minnesota

NASA Astrophysics Data System (ADS)

Riggs, C.; Kolka, R. K.; Nater, E. A.; Witt, E.; Wickman, T.; Woodruff, L. G.; Butcher, J.

2016-12-01

Wildland fire can significantly alter mercury (Hg) cycling on land and in adjacent aquatic environments. In addition to enhancing local atmospheric Hg deposition, fire can influence terrestrial movement of Hg and other elements into lakes via runoff from burned upland soil. However, the impact of fire on water quality and the accumulation of Hg in fish remains equivocal. We investigated the effects of fire - specifically a low severity prescribed fire and moderate severity wildfire - on young-of-the-year yellow perch (Perca flavescens) and lake chemistry in two small remote watersheds in the Boundary Waters Canoe Area Wilderness in northeastern Minnesota using a paired watershed approach (fire-impacted vs. control watershed). Prior to fire, surface soil in the two study watersheds contained significant loads of Hg, mainly from atmospheric deposition. We expected fire to increase transport and deposition of Hg from smoke and burned soil into the fire-impacted lake, leading to changes in lake productivity and fish Hg loads. In contrast to our prediction, and despite significant effects of the moderate severity wildfire fire on upland soil Hg stocks, fish Hg accumulation and lake productivity were not affected by fire. Instead, climate and lake water levels were the strongest predictors of lake chemistry and fish responses in our study lakes. Our results suggest that low to moderate severity wildland fire does not alter lake productivity nor Hg accumulation in young-of-the-year yellow perch in these small, shallow lakes in the northern deciduous and boreal forest region. The effect of a high severity fire remains to be tested.

Using Space Technologies for a timely detection of forest fires: the experience of end-users in 3 Italian Regions

NASA Astrophysics Data System (ADS)

Filizzola, Carolina; Belloni, Antonella; Benigno, Giuseppe; Biancardi, Alberto; Corrado, Rosita; Coviello, Irina; De Costanzo, Giovanni; Genzano, Nicola; Lacava, Teodosio; Lisi, Mariano; Marchese, Francesco; Mazzeo, Giuseppe; Merzagora, Cinzio; Paciello, Rossana; Pergola, Nicola; Sannazzaro, Filomena; Serio, Salvatore; Tramutoli, Valerio

2013-04-01

Every year, hundreds of thousands of hectares of European forests are destroyed by fires. Due to the particular topography, landscape and demographic distribution in Europe (very different from typical scenarios of China, USA, Canada and Australia), rapidity in fire sighting is still the determining factor in limiting damages to people and goods. Moreover, the possibility of early fire detection means also potentially to reduce the size of the event to be faced, the necessary fire fighting resources and, therefore, even the reaction times. In such a context, integration of satellite technologies (mainly high temporal resolution data) and traditional surveillance systems within the fire fighting procedures seems to positively impact on the effectiveness of active fire fighting as demonstrated by recent experiences over Italian territory jointly performed by University of Basilicata, IMAA-CNR and Local Authorities. Real time implementation was performed since 2007, during fire seasons, over several Italian regions with different fire regimes and features, in order to assess the actual potential of different satellite-based fire detection products to support regional and local authorities in efficiently fighting fires and better mitigating their negative effects. Real-time campaigns were carried out in strict collaboration with end-users within the framework of specific projects (i.e. the AVVISA, AVVISTA and AVVISA-Basilicata projects) funded by Civil Protection offices of Regione Lombardia, Provincia Regionale di Palermo and Regione Basilicata in charge of fire risk management and mitigation. A tailored training program was dedicated to the personnel of Regional Civil Protection offices in order to ensure the full understanding and the better integration of satellite based products and tools within the existing fire fighting protocols. In this work, outcomes of these practices are shown and discussed, especially highlighting the impact that a real time satellite system may have in assisting and complementing traditional surveillance systems to mitigate damages due to fires. In particular, the usefulness of satellite technology in an operational context was demonstrated mainly in reference to: i) the possibility of identifying fires at an early stage (so avoiding that small hotbeds could extend and become dangerous for citizens and destructive for environmental protected areas) as well as ii) the possibility to have an effective territorial control (e.g. discovering illegal burning fires such as unauthorized cleaning fires, and permitting local authorities to rapidly intervene and catch red-handed pyromaniacs).

Historical dominance of low-severity fire in dry and wet mixed-conifer forest habitats of the endangered terrestrial Jemez Mountains salamander (Plethodon neomexicanus)

USGS Publications Warehouse

Margolis, Ellis; Malevich, Steven B.

2016-01-01

Anthropogenic alteration of ecosystem processes confounds forest management and conservation of rare, declining species. Restoration of forest structure and fire hazard reduction are central goals of forest management policy in the western United States, but restoration priorities and treatments have become increasingly contentious. Numerous studies have documented changes in fire regimes, forest stand structure and species composition following a century of fire exclusion in dry, frequent-fire forests of the western U.S. (e.g., ponderosa pine and dry mixed-conifer). In contrast, wet mixed-conifer forests are thought to have historically burned infrequently with mixed- or high-severity fire—resulting in reduced impacts from fire exclusion and low restoration need—but data are limited. In this study we quantified the current forest habitat of the federally endangered, terrestrial Jemez Mountains salamander (Plethodon neomexicanus) and compared it to dendroecological reconstructions of historical habitat (e.g., stand structure and composition), and fire regime parameters along a gradient from upper ponderosa pine to wet mixed-conifer forests. We found that current fire-free intervals in Jemez Mountains salamander habitat (116–165 years) are significantly longer than historical intervals, even in wet mixed-conifer forests. Historical mean fire intervals ranged from 10 to 42 years along the forest gradient. Low-severity fires were historically dominant across all forest types (92 of 102 fires). Although some mixed- or highseverity fire historically occurred at 67% of the plots over the last four centuries, complete mortality within 1.0 ha plots was rare, and asynchronous within and among sites. Climate was an important driver of temporal variability in fire severity, such that mixed- and high-severity fires were associated with more extreme drought than low-severity fires. Tree density in dry conifer forests historically ranged from open (90 trees/ha) to moderately dense (400 trees/ha), but has doubled on average since fire exclusion. Infill of fire-sensitive tree species has contributed to the conversion of historically dry mixedconifer to wet mixed-conifer forest. We conclude that low-severity fire, which has been absent for over a century, was a critical ecosystem process across the forest gradient in Jemez Mountains salamander habitat, and thus is an important element of ecosystem restoration, resilience, and rare species recovery.

Trends and causes of severity, size, and number of fires in northwestern California, USA

Treesearch

J. D. Miller; Carl Skinner; H. D. Safford; Eric E. Knapp; C. M. Ramirez

2012-01-01

Research in the last several years has indicated that fire size and frequency are on the rise in western U.S. forests. Although fire size and frequency are important, they do not necessarily scale with ecosystem effects of fire, as different ecosystems have different ecological and evolutionary relationships with fire. Our study assessed trends and patterns in fire...

Short- and long-term effects of fire on carbon in US dry temperate forest systems

USGS Publications Warehouse

Hurteau, Matthew D.; Brooks, Matthew L.

2011-01-01

Forests sequester carbon from the atmosphere, and in so doing can mitigate the effects of climate change. Fire is a natural disturbance process in many forest systems that releases carbon back to the atmosphere. In dry temperate forests, fires historically burned with greater frequency and lower severity than they do today. Frequent fires consumed fuels on the forest floor and maintained open stand structures. Fire suppression has resulted in increased understory fuel loads and tree density; a change in structure that has caused a shift from low- to high-severity fires. More severe fires, resulting in greater tree mortality, have caused a decrease in forest carbon stability. Fire management actions can mitigate the risk of high-severity fires, but these actions often require a trade-off between maximizing carbon stocks and carbon stability. We discuss the effects of fire on forest carbon stocks and recommend that managing forests on the basis of their specific ecologies should be the foremost goal, with carbon sequestration being an ancillary benefit. ?? 2011 by American Institute of Biological Sciences. All rights reserved.

Surface Fire Influence on Carbon Balance Components in Scots Pine Forest of Siberia, Russia

NASA Astrophysics Data System (ADS)

Kukavskaya, E.; Ivanova, G. A.; Conard, S. G.; Soja, A. J.

2008-12-01

Wildfire is one of the most important disturbances in boreal forests, and it can have a profound effect on forest-atmosphere carbon exchange. Pinus sylvestris (Scots pine) stands of Siberia are strongly impacted by fires of low to high severity. Biomass distribution in mature lichen/feathermoss Scots pine stands indicates that they are carbon sinks before fire. Fires contribute significantly to the carbon budget resulting in a considerable carbon efflux, initially through direct consumption of forest fuels and later as a result of tree mortality and decomposition of dead material accumulated on the forest floor. In initial postfire years these processes dominate over photosynthetic carbon assimilation, and the ecosystems become a carbon source. Over several postfire years, above-ground carbon in dead biomass tends to increase, with the increase depending significantly on fire severity. High-severity fire enhances dead biomass carbon, while moderate- and low-severity fires have minimal effect on above-ground carbon distribution in Scots pine ecosystems. Dead stand biomass carbon increases, primarily during the first two years following fires, due to tree mortality. This increase can account for up to 12.4% of the total stand biomass after low- and moderate- intensity fires. We found tree dieback following a high-intensity fire is an order of magnitude higher, and thus the dead biomass increases up to 88.1% of total above-ground biomass. Photosynthetic CO2 uptake decreases with increasing tree mortality, and needle foliage and bark are incorporated into the upper layer of the forest floor in the course of years. Ground vegetation and duff carbon were >90, 71-83, and 82% of prefire levels after fires of low, moderate, and high severity, respectively for the first 4 to 5 years after fire. Fires of low and moderate severity caused down woody fuel carbon to increase by 2.1 and 3.6 t ha-1 respectively by four years after burning as compared to the pre-fire values. Climate change and increasing drought length observed in recent decades have increased the probability of high-intensity fire occurrence. Areas burned have increased in extent and severity across Siberia, resulting in increased carbon emissions to the atmosphere from fuel combustion and post fire decomposition.

Land cover change interacts with drought severity to change fire regimes in Western Amazonia.

PubMed

Gutiérrez-Vélez, Víctor H; Uriarte, María; DeFries, Ruth; Pinedo-Vásquez, Miguel; Fernandes, Katia; Ceccato, Pietro; Baethgen, Walter; Padoch, Christine

Fire is becoming a pervasive driver of environmental change in Amazonia and is expected to intensify, given projected reductions in precipitation and forest cover. Understanding of the influence of post-deforestation land cover change on fires in Amazonia is limited, even though fires in cleared lands constitute a threat for ecosystems, agriculture, and human health. We used MODIS satellite data to map burned areas annually between 2001 and 2010. We then combined these maps with land cover and climate information to understand the influence of land cover change in cleared lands and dry-season severity on fire occurrence and spread in a focus area in the Peruvian Amazon. Fire occurrence, quantified as the probability of burning of individual 232-m spatial resolution MODIS pixels, was modeled as a function of the area of land cover types within each pixel, drought severity, and distance to roads. Fire spread, quantified as the number of pixels burned in 3 × 3 pixel windows around each focal burned pixel, was modeled as a function of land cover configuration and area, dry-season severity, and distance to roads. We found that vegetation regrowth and oil palm expansion are significantly correlated with fire occurrence, but that the magnitude and sign of the correlation depend on drought severity, successional stage of regrowing vegetation, and oil palm age. Burning probability increased with the area of nondegraded pastures, fallow, and young oil palm and decreased with larger extents of degraded pastures, secondary forests, and adult oil palm plantations. Drought severity had the strongest influence on fire occurrence, overriding the effectiveness of secondary forests, but not of adult plantations, to reduce fire occurrence in severely dry years. Overall, irregular and scattered land cover patches reduced fire spread but irregular and dispersed fallows and secondary forests increased fire spread during dry years. Results underscore the importance of land cover management for reducing fire proliferation in this landscape. Incentives for promoting natural regeneration and perennial crops in cleared lands might help to reduce fire risk if those areas are protected against burning in early stages of development and during severely dry years.

Spectral Mixture Analysis to map burned areas in Brazil's deforestation arc from 1992 to 2011

NASA Astrophysics Data System (ADS)

Antunes Daldegan, G.; Ribeiro, F.; Roberts, D. A.

2017-12-01

The two most extensive biomes in South America, the Amazon and the Cerrado, are subject to several fire events every dry season. Both are known for their ecological and environmental importance. However, due to the intensive human occupation over the last four decades, they have been facing high deforestation rates. The Cerrado biome is adapted to fire and is considered a fire-dependent landscape. In contrast, the Amazon as a tropical moist broadleaf forest does not display similar characteristics and is classified as a fire-sensitive landscape. Nonetheless, studies have shown that forest areas that have already been burned become more prone to experience recurrent burns. Remote sensing has been extensively used by a large number of researchers studying fire occurrence at a global scale, as well as in both landscapes aforementioned. Digital image processing aiming to map fire activity has been applied to a number of imagery from sensors of various spatial, temporal, and spectral resolutions. More specifically, several studies have used Landsat data to map fire scars in the Amazon forest and in the Cerrado. An advantage of using Landsat data is the potential to map fire scars at a finer spatial resolution, when compared to products derived from imagery of sensors featuring better temporal resolution but coarser spatial resolution, such as MODIS (Moderate Resolution Imaging Spectrometer) and GOES (Geostationary Operational Environmental Satellite). This study aimed to map burned areas present in the Amazon-Cerrado transition zone by applying Spectral Mixture Analysis on Landsat imagery for a period of 20 years (1992-2011). The study area is a subset of this ecotone, centered at the State of Mato Grosso. By taking advantage of the Landsat 5TM and Landsat 7ETM+ imagery collections available in Google Earth Engine platform and applying Spectral Mixture Analysis (SMA) techniques over them permitted to model fire scar fractions and delimitate burned areas. Overlaying yearly burned areas allowed to identify areas with high fire recurrence.

Growth Response of Pinus ponderosa following a Mixed-Severity Wildfire in the Black Hills, South Dakota

Treesearch

Tara keyser; Fredrick Smith; Wayne Sheppard

2010-01-01

In late summer 2000 the Jasper Fire burned ~34,000 ha of ponderosa pine forest in the Black Hills of South Dakota. Although regarded as a catastrophic event, the Jasper Fire left a mosaic of fire severity across the landscape, with live trees present in areas burned under low and moderate fire severity. In October 2005, we cored 96 trees from unburned, low-severity,...

Predicting wildfire ignitions, escapes, and large fire activity using Predictive Service’s 7-Day Fire Potential Outlook in the western USA

Treesearch

Karin L. Riley; Crystal Stonesifer; Haiganoush Preisler; Dave Calkin

2014-01-01

Can fire potential forecasts assist with pre-positioning of fire suppression resources, which could result in a cost savings to the United States government? Here, we present a preliminary assessment of the 7-Day Fire Potential Outlook forecasts made by the Predictive Services program. We utilized historical fire occurrence data and archived forecasts to assess how...

Climatic warming strengthens a positive feedback between alpine shrubs and fire.

PubMed

Camac, James S; Williams, Richard J; Wahren, Carl-Henrik; Hoffmann, Ary A; Vesk, Peter A

2017-08-01

Climate change is expected to increase fire activity and woody plant encroachment in arctic and alpine landscapes. However, the extent to which these increases interact to affect the structure, function and composition of alpine ecosystems is largely unknown. Here we use field surveys and experimental manipulations to examine how warming and fire affect recruitment, seedling growth and seedling survival in four dominant Australian alpine shrubs. We found that fire increased establishment of shrub seedlings by as much as 33-fold. Experimental warming also doubled growth rates of tall shrub seedlings and could potentially increase their survival. By contrast, warming had no effect on shrub recruitment, postfire tussock regeneration, or how tussock grass affected shrub seedling growth and survival. These findings indicate that warming, coupled with more frequent or severe fires, will likely result in an increase in the cover and abundance of evergreen shrubs. Given that shrubs are one of the most flammable components in alpine and tundra environments, warming is likely to strengthen an existing feedback between woody species abundance and fire in these ecosystems. © 2017 John Wiley & Sons Ltd.

Calibration and validation of the relative differenced Normalized Burn Ratio (RdNBR) to three measures of fire severity in the Sierra Nevada and Klamath Mountains, California, USA

USGS Publications Warehouse

Miller, J.D.; Knapp, E.E.; Key, C.H.; Skinner, C.N.; Isbell, C.J.; Creasy, R.M.; Sherlock, J.W.

2009-01-01

Multispectral satellite data have become a common tool used in the mapping of wildland fire effects. Fire severity, defined as the degree to which a site has been altered, is often the variable mapped. The Normalized Burn Ratio (NBR) used in an absolute difference change detection protocol (dNBR), has become the remote sensing method of choice for US Federal land management agencies to map fire severity due to wildland fire. However, absolute differenced vegetation indices are correlated to the pre-fire chlorophyll content of the vegetation occurring within the fire perimeter. Normalizing dNBR to produce a relativized dNBR (RdNBR) removes the biasing effect of the pre-fire condition. Employing RdNBR hypothetically allows creating categorical classifications using the same thresholds for fires occurring in similar vegetation types without acquiring additional calibration field data on each fire. In this paper we tested this hypothesis by developing thresholds on random training datasets, and then comparing accuracies for (1) fires that occurred within the same geographic region as the training dataset and in similar vegetation, and (2) fires from a different geographic region that is climatically and floristically similar to the training dataset region but supports more complex vegetation structure. We additionally compared map accuracies for three measures of fire severity: the composite burn index (CBI), percent change in tree canopy cover, and percent change in tree basal area. User's and producer's accuracies were highest for the most severe categories, ranging from 70.7% to 89.1%. Accuracies of the moderate fire severity category for measures describing effects only to trees (percent change in canopy cover and basal area) indicated that the classifications were generally not much better than random. Accuracies of the moderate category for the CBI classifications were somewhat better, averaging in the 50%-60% range. These results underscore the difficulty in isolating fire effects to individual vegetation strata when fire effects are mixed. We conclude that the models presented here and in Miller and Thode ([Miller, J.D. & Thode, A.E., (2007). Quantifying burn severity in a heterogeneous landscape with a relative version of the delta Normalized Burn Ratio (dNBR). Remote Sensing of Environment, 109, 66-80.]) can produce fire severity classifications (using either CBI, or percent change in canopy cover or basal area) that are of similar accuracy in fires not used in the original calibration process, at least in conifer dominated vegetation types in Mediterranean-climate California.

Holocene Fire, Climate, and Geomorphic Response: Perspectives From the Past and Indications for the Future

NASA Astrophysics Data System (ADS)

Meyer, G. A.; Pierce, J. L.; Frechette, J. D.; New, J.; Jull, A.

2006-12-01

Increased wildfire activity has accompanied late 20th-century to present warming across the diverse conifer forests of western North America. In ponderosa pine forests in particular, large, severe wildfires and ensuing erosion and debris flows appear unprecedented in light of tree-ring fire-scar records, and are often attributed to increased stand density following Euro-American settlement and fire suppression starting in the late 1800s. Yet, presettlement periods in fire-scar records correspond to mostly cooler Little Ice Age climates, when we expect that severe fires may be less probable. AMS 14C dating of fire-related alluvial-fan deposits provides a longer-term context for assessing links between fire, climate, erosion, and anthropogenic change. Infrequent high-severity fire is typical of cool, high-elevation Yellowstone National Park (YNP). Fire-related debris flows were common in YNP 2350-2000 cal yr BP and in Medieval time 1050-650 BP, both relatively warm periods at many sites across the Northern Hemisphere. Drier, low-elevation ponderosa forests in central Idaho also experienced severe fires and debris flows at these times, and ~25% of fan aggradation in the last 4000 yr occurred via postfire debris flows within the 400-yr Medieval period containing widespread, multidecadal droughts (Cook et al. 2004). Few fire-related deposits in YNP date to the Little Ice Age and prior cold episodes ca. 1400 and 2800 BP. At these same times, thin charcoal-bearing deposits indicate frequent low-severity fires in Idaho, where cooler, effectively wetter climates promoted growth of grass and fine fuels that promoted surface fires in the typically dry summers of this region. Initial data from varied forest types in the monsoonal (dry spring, wet summer) climate of the Sacramento Mountains, New Mexico, indicate voluminous fire-related sedimentation 6000-4500 BP, consistent with a warm middle Holocene. Fire-induced debris flows were less frequent in the late Holocene, but indicate that some severe fires affected ponderosa pine-dominated forests. Therefore, modern postfire debris flows are not without precedent in any of these areas, where fire has been an important catalyst for episodic erosion. Each record indicates an increased probability of severe fire with warmer climates. As greenhouse gas increases are virtually assured over the next century, impacts on fire and erosion have likely just begun. Earlier snowmelt accompanying warming lengthens the fire season in much of the Rocky Mountains, including YNP and central Idaho (Westerling et al. 2006). In ponderosa and similar forests where surface fires were suppressed by humans, increased stand density compounds the effect of warming. Increasing temperatures may also heighten precipitation intensity, producing greater postfire erosion. Although Holocene history provides imperfect analogs for a uniquely anthropogenic future, the sensitivity of fire regimes to past warming portends future increases in severe fires and geomorphic change.

Cannabidiol as a Potential Treatment for Febrile Infection-Related Epilepsy Syndrome (FIRES) in the Acute and Chronic Phases.

PubMed

Gofshteyn, Jacqueline S; Wilfong, Angus; Devinsky, Orrin; Bluvstein, Judith; Charuta, Joshi; Ciliberto, Michael A; Laux, Linda; Marsh, Eric D

2017-01-01

Febrile infection-related epilepsy syndrome (FIRES) is a devastating epilepsy affecting normal children after a febrile illness. FIRES presents with an acute phase with super-refractory status epilepticus and all patients progress to a chronic phase with persistent refractory epilepsy. The typical outcome is severe encephalopathy or death. The authors present 7 children from 5 centers with FIRES who had not responded to antiepileptic drugs or other therapies who were given cannabadiol (Epidiolex, GW Pharma) on emergency or expanded investigational protocols in either the acute or chronic phase of illness. After starting cannabidiol, 6 of 7 patients' seizures improved in frequency and duration. One patient died due to multiorgan failure secondary to isoflourane. An average of 4 antiepileptic drugs were weaned. Currently 5 subjects are ambulatory, 1 walks with assistance, and 4 are verbal. While this is an open-label case series, the authors add cannabidiol as a possible treatment for FIRES.

Selection and Use of Manganese Dioxide by Neanderthals

PubMed Central

Heyes, Peter J.; Anastasakis, Konstantinos; de Jong, Wiebren; van Hoesel, Annelies; Roebroeks, Wil; Soressi, Marie

2016-01-01

Several Mousterian sites in France have yielded large numbers of small black blocs. The usual interpretation is that these ‘manganese oxides’ were collected for their colouring properties and used in body decoration, potentially for symbolic expression. Neanderthals habitually used fire and if they needed black material for decoration, soot and charcoal were readily available, whereas obtaining manganese oxides would have incurred considerably higher costs. Compositional analyses lead us to infer that late Neanderthals at Pech-de-l’Azé I were deliberately selecting manganese dioxide. Combustion experiments and thermo-gravimetric measurements demonstrate that manganese dioxide reduces wood’s auto-ignition temperature and substantially increases the rate of char combustion, leading us to conclude that the most beneficial use for manganese dioxide was in fire-making. With archaeological evidence for fire places and the conversion of the manganese dioxide to powder, we argue that Neanderthals at Pech-de-l’Azé I used manganese dioxide in fire-making and produced fire on demand. PMID:26922901

The Recovery of a Clinical Database Management System after Destruction by Fire *

PubMed Central

Covvey, H.D.; McAlister, N.H.; Greene, J.; Wigle, E.D.

1981-01-01

In August 1980 a fire in the Cardiovascular Unit at Toronto General Hospital severely damaged the physical plant and rendered all on-site equipment unrecoverable. Among the hardware items in the fire was the computer which supports our cardiovascular database system. Within hours after the fire it was determined that the computer was no longer serviceable. Beyond off-site back-up tapes, there was the possibility that recent records on the computer had suffered a similar fate. Immediate procedures were instituted to obtain a replacement computer system and to clean media to permit data recovery. Within 2 months a partial system was supporting all users, and all data was recovered and being used. The destructive potential of a fire is rarely seriously considered relative to computer equipment in our clinical environments. Full-replacement value insurance; an excellent equipment supplier with the capacity to respond to an emergency; backup and recovery procedures with off-site storage; and dedicated staff are key hedges against disaster.

Hydrologic impacts of high severity wildfire: Learning from the past and preparing for the future

Treesearch

Daniel G. Neary; Karen A. Koestner; Ann Youberg

2011-01-01

Wildfire is a natural disturbance with epic potential to drastically alter watershed hydrologic condition. Basins with high-burn severity, especially those with steep previously forested terrain, have flashier hydrographs and can produce peak-flows orders of magnitude greater than pre-fire conditions. This is due to fundamental changes in the hydrology of burnt...

Reburn severity in managed and unmanaged vegetation in a large wildfire

PubMed Central

Thompson, Jonathan R.; Spies, Thomas A.; Ganio, Lisa M.

2007-01-01

Debate over the influence of postwildfire management on future fire severity is occurring in the absence of empirical studies. We used satellite data, government agency records, and aerial photography to examine a forest landscape in southwest Oregon that burned in 1987 and then was subject, in part, to salvage-logging and conifer planting before it reburned during the 2002 Biscuit Fire. Areas that burned severely in 1987 tended to reburn at high severity in 2002, after controlling for the influence of several topographical and biophysical covariates. Areas unaffected by the initial fire tended to burn at the lowest severities in 2002. Areas that were salvage-logged and planted after the initial fire burned more severely than comparable unmanaged areas, suggesting that fuel conditions in conifer plantations can increase fire severity despite removal of large woody fuels. PMID:17563370

Impact of Wildfire on Microbial Biomass in Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Murphy, M. A.; Fairbanks, D.; Chorover, J.; Gallery, R. E.; Rich, V. I.

2014-12-01

The recovery of the critical zone following disturbances such as wildfire is not fully understood. Wildfires have increased in size and intensity in western US forests in recent years and these fires influence soil microbial communities, both in composition and overall biomass. Studies have typically shown a 50% post-fire decline in overall microbial biomass (µg per g soil) that can persist for years. There is however, some variability in the severity of biomass decline, and its relationship with burn severity and landscape position have not yet been studied. Since microbial biomass has a cascade of impacts in soil systems, from helping control the rate and diversity the biogeochemical processes occurring, to promoting soil fertility, to impacting the nature and structure of soil carbon (C), fire's lasting impact on it is one mechanistic determinant of the overall post-fire recovery of impacted ecosystems. Additionally, microbial biomass measurements hold potential for testing and incorporation into land surface models (NoahMP, CLM, etc.) in order to improve estimates of long-term effects of climate change and disturbances such as fire on the C cycle. In order to refine our understanding of the impact of fire on microbial biomass and then relate that to biogeochemical processes and ecosystem recovery, we used chloroform fumigation extraction to quantify total microbial biomass C (Cmic ). One year after the June 2013 Thompson Ridge fire in the Jemez River Basin Critical Zone Observatory, we are measuring the Cmic of 22 sites across a gradient of burn severities and 4 control unburned sites, from six depth intervals at each site (0-2, 2-5, 5-10, 10-20, 20-30, and 30-40 cm). We hypothesize that the decrease in microbial biomass in burned sites relative to control sites will correlate with changes in soil biogeochemistry related to burn severity; and that the extent of the impact on biomass will be inversely related to depth in the soil column. Additionally, as the project progresses, we will relate microbial biomass to microbial functional assays as proxy for biogeochemical activity, and test variation by landscape position and aspect.

The 2002 Hayman Fire - ecological benefit or catastrophe? An understory plant community perspective

Treesearch

Paula Fornwalt

2013-01-01

Fire has long been a keystone ecological process in Western forests. In ponderosa pine (Pinus ponderosa)/Douglas-fir (Pseudotsuga menziesii) forests of the Colorado Front Range, historical fires are believed to have been "mixed severity" in nature. That means that these fires are believed to have typically burned within a range of severities from low severity...

Biophysical Interactions within Step-Pool Mountain Streams Following Wildfire

NASA Astrophysics Data System (ADS)

Parker, A.; Chin, A.; O'Dowd, A. P.

2014-12-01

Recovery of riverine ecosystems following disturbance is driven by a variety of interacting processes. Wildfires pose increasing disturbances to riverine landscapes, with rising frequencies and magnitudes owing to warming climates and increased fuel loads. The effects of wildfire include loss of vegetation, elevated runoff and flash floods, erosion and deposition, and changing biological habitats and communities. Understanding process interactions in post-fire landscapes is increasingly urgent for successful management and restoration of affected ecosystems. In steep channels, steps and pools provide prominent habitats for organisms and structural integrity in high energy environments. Step-pools are typically stable, responding to extreme events with recurrence intervals often exceeding 50 years. Once wildfire occurs, however, intensification of post-fire flood events can potentially overpower the inherent stability of these systems, with significant consequences for aquatic life and human well-being downstream. This study examined the short-term response of step-pool streams following the 2012 Waldo Canyon Fire in Colorado. We explored interacting feedbacks among geomorphology, hydrology, and ecology in the post-fire environment. At selected sites with varying burn severity, we established baseline conditions immediately after the fire with channel surveys, biological assessment using benthic macroinvertebrates, sediment analysis including pebble counts, and precipitation gauging. Repeat measurements after major storm events over several years enabled analysis of the interacting feedbacks among post-fire processes. We found that channels able to retain the step-pool structure changed less and facilitated recovery more readily. Step habitats maintained higher percentages of sensitive macroinvertebrate taxa compared to pools through post-fire floods. Sites burned with high severity experienced greater reduction in the percentage of sensitive taxa. The decimation of macroinvertebrates closely coincides with the physical destruction of the step-pool morphology. The role that step-pools play in enhancing the ecological quality of fluvial systems, therefore, provides a key focus for effective management and restoration of aquatic resources following wildfires.

Shifts in microbial communities and soil nutrients along a fire chronosequence in Alaskan boreal forest

NASA Astrophysics Data System (ADS)

Treseder, K. K.; Mack, M. C.; Cross, A.

2002-12-01

Fires are important pathways of carbon loss from boreal forests, while microbial communities form equally important mechanisms for carbon accumulation between fires. We used a chronosequence in Alaska to examine shifts in microbial abundance and community composition in the several decades following severe fire, and then related these responses to soil characteristics in the same sites. The sites are located in upland forests near Delta Junction, Alaska, and represent stages at 3-, 15-, 45-, and over 100-yr following fire. Plant communities shift from herbaceous species in the youngest site, to deciduous shrubs and trees (e.g. Populus tremuloides and Salix) in the intermediate sites, to black spruce (Picea mariana) forest in the oldest site. Soil organic matter accumulated 2.8-fold over time. Potential mineralization was highest in the intermediate-aged sites, as was nitrification and standing pools of inorganic nitrogen. In contrast, inorganic phosphorus pools were highest immediately following fire, and then decreased nine-fold with age. As measured with BiologTM plates, bacterial diversity and abundance were greatest in the oldest sites. Plant roots in the intermediate-aged sites displayed higher colonization by ecto- and arbuscular mycorrhizal fungi than those in the youngest and oldest sites. Likewise, glomalin, a glycoprotein produced by arbuscular mycorrhizal fungi, was most abundant in the 14-yr old site. Glomalin is believed to contribute to the formation of water-stable aggregates in the soil. However, water stable aggregates were most abundant in the younger sites and did not follow the pattern of glomalin or arbuscular mycorrhizal abundance. Our results indicate that fire may maintain landscape-level diversity of microbial functional groups, and that carbon sequestration in microbial tissues (e.g. glomalin and fungal biomass) may be greatest in areas that have burned several decades earlier. Changes in soil structure may not be directly attributable to microbial activity.

Unitary synaptic connections among substantia nigra pars reticulata neurons

PubMed Central

Wilson, Charles J.

2016-01-01

Neurons in substantia nigra pars reticulata (SNr) are synaptically coupled by local axon collaterals, providing a potential mechanism for local signal processing. Because SNr neurons fire spontaneously, these synapses are constantly active. To investigate their properties, we recorded spontaneous inhibitory postsynaptic currents (sIPSCs) from SNr neurons in brain slices, in which afferents from upstream nuclei are severed, and the cells fire rhythmically. The sIPSC trains contained a mixture of periodic and aperiodic events. Autocorrelation analysis of sIPSC trains showed that a majority of cells had one to four active unitary inputs. The properties of the unitary IPSCs (uIPSCs) were analyzed for cells with one unitary input, using a model of periodic presynaptic firing and stochastic synaptic transmission. The inferred presynaptic firing rates and coefficient of variation of interspike intervals (ISIs) corresponded well with direct measurements of spiking in SNr neurons. Methods were developed to estimate the success probability, amplitude distributions, and kinetics of the uIPSCs, while removing the contribution from aperiodic sIPSCs. The sIPSC amplitudes were not increased upon release from halorhodopsin silencing, suggesting that most synapses were not depressed at the spontaneous firing rate. Gramicidin perforated-patch recordings indicated that the average reversal potential of spontaneous inhibitory postsynaptic potentials was −64 mV. Because of the change in driving force across the ISI, the unitary inputs are predicted to have a larger postsynaptic impact when they arrive late in the ISI. Simulations of network activity suggest that this very sparse inhibitory coupling may act to desynchronize the activity of SNr neurons while having only a small effect on firing rate. PMID:26961101

[Patterns of action potential firing in cortical neurons of neonatal mice and their electrophysiological property].

PubMed

Furong, Liu; Shengtian, L I

2016-05-25

To investigate patterns of action potential firing in cortical heurons of neonatal mice and their electrophysiological properties. The passive and active membrane properties of cortical neurons from 3-d neonatal mice were observed by whole-cell patch clamp with different voltage and current mode. Three patterns of action potential firing were identified in response to depolarized current injection. The effects of action potential firing patterns on voltage-dependent inward and outward current were found. Neurons with three different firing patterns had different thresholds of depolarized current. In the morphology analysis of action potential, the three type neurons were different in rise time, duration, amplitude and threshold of the first action potential evoked by 80 pA current injection. The passive properties were similar in three patterns of action potential firing. These results indicate that newborn cortical neurons exhibit different patterns of action potential firing with different action potential parameters such as shape and threshold.

Investigating the haze transport from 1997 biomass burning in Southeast Asia: its impact upon Singapore

NASA Astrophysics Data System (ADS)

Koe, Lawrence C. C.; Arellano, Avelino F.; McGregor, John L.

The 1997 Indonesia forest fires was an environmental disaster of exceptional proportions. Such a disaster caused massive transboundary air pollution and indiscriminate destruction of biodiversity in the world. The immediate consequence of the fires was the production of large amounts of haze in the region, causing visibility and health problems within Southeast Asia. Furthermore, fires of these magnitudes are potential contributors to global warming and climate change due to the emission of large amounts of greenhouse gases and other pyrogenic products.The long-range transport of fire-related haze in the region is investigated using trajectories from the CSIRO Division of Atmospheric Research Limited Area Model (DARLAM). Emission scenarios were constructed for hotspot areas in Sumatra and Kalimantan for the months of September and October 1997 to determine the period and fire locations most critical to Singapore. This study also examines some transport issues raised from field observations. Results show that fires in the coastal areas of southeast Sumatra and southwest Kalimantan can be potential contributors to transboundary air pollution in Singapore. Singapore was directly affected by haze from these areas whereas Kuala Lumpur was heavily affected by the haze coming from Sumatra. In most cases, Singapore was more affected by fires from Kalimantan than was Kuala Lumpur. This was mainly a result of the shifting of monsoons. The transition of monsoons resulted in weaker low-level winds and shifted convergence zones near to the southeast of Peninsular Malaysia. In addition to severe drought and massive fire activity in 1997, the timing of the monsoon transition has a strong influence on haze transport in the region.

Toward a more ecologically informed view of severe forest fires

Treesearch

Richard L. Hutto; Robert E. Keane; Rosemary L. Sherriff; Christopher T. Rota; Lisa A. Eby; Vicki Saab

2016-01-01

We use the historical presence of high-severity fire patches in mixed-conifer forests of the western United States to make several points that we hope will encourage development of a more ecologically informed view of severe wildland fire effects. First, many plant and animal species use, and have sometimes evolved to depend on, severely burned forest...

Assessing Climate Change in Early Warm Season and Impacts on Wildfire Potential in the Southwestern United States

NASA Astrophysics Data System (ADS)

Kafatos, M.; Kim, S. H.; Kim, J.; Nghiem, S. V.; Fujioka, F.; Myoung, B.

2016-12-01

Wildfires are an important concern in the Southwestern United States (SWUS) where the prevalent semi-arid to arid climate, vegetation types and hot and dry warm seasons challenge strategic fire management. Although they are part of the natural cycle related to the region's climate, significant growth of urban areas and expansion of the wildland-urban interface, have made wildfires a serious high-risk hazard. Previous studies also showed that the SWUS region is prone to frequent droughts due to large variations in wet season rainfall and has suffered from a number of severe wildfires in the recent decades. Despite the increasing trend in large wildfires, future wildfire risk assessment studies at regional scales for proactive adaptations are lacking. Our previous study revealed strong correlations between the North Atlantic Oscillation (NAO) and temperatures during March-June in SWUS. The abnormally warm and dry conditions in an NAO-positive spring, combined with reduced winter precipitation, can cause an early start of a fire season and extend it for several seasons, from late spring to fall. A strong interannual variation of the Keetch-Byram Drought Index (KBDI) during the early warm season was also found in the 35 year period 1979 - 2013 of the North American Regional Reanalysis (NARR) dataset. Thus, it is crucial to investigate the climate change impact that early warm season temperatures have on future wildfire danger potential. Our study reported here examines fine-resolution fire-weather variables for 2041-2070 projected in the North American Regional Climate Change Assessment Program (NARCCAP). The high-resolution climate data were obtained from multiple regional climate models (RCM) driven by multiple climate scenarios projected from multiple global climate models (GCMs) in conjunction with multiple greenhouse gas concentration pathways. The local wildfire potential in future climate is investigated using both the Keetch-Byram Drought Index (KBDI) and the Canadian Fire Weather Index (FWI) which have been widely used for assessing wildfire potential in the U.S.A and Canada, respectively.

Low Level Impacts on Fire Evolution in the Mack Lake and Other Severe Wildfires

Treesearch

Joseph J. Charney; Xindi Bian; Brian E. Potter; Warren E. Heilman

2003-01-01

The 2000 fire season brought to the forefront the issue of severe wildland fires in the United States. To address the need for new research and for the development of predictive tools for managing wildland fires, Congress allocated funding under the National Fire Plan (NFP) to better equip government agencies to fight and study forest fires. As part of the NFP research...

Mixed-severity fire fosters heterogeneous spatial patterns of conifer regeneration in a dry conifer forest

Treesearch

Sparkle L. Malone; Paula J. Fornwalt; Mike A. Battaglia; Marin E. Chambers; Jose M. Iniguez; Carolyn H. Sieg

2018-01-01

We examined spatial patterns of post-fire regenerating conifers in a Colorado, USA, dry conifer forest 11-12 years following the reintroduction of mixed-severity fire. We mapped and measured all post-fire regenerating conifers, as well as all other post-fire regenerating trees and all residual (i.e., surviving) trees, in three 4-ha plots following the 2002 Hayman Fire...

Northwest California National Forests fire severity monitoring 1987-2008

Treesearch

Jay D. Miller; Carl N. Skinner; Hugh D. Safford; Eric E. Knapp; Carlos M. Ramirez

2012-01-01

Research in the last several years has indicated that the frequency of large fires is on the rise in western US forests. Although fire size and frequency are important, they do not necessarily provide information concerning the effects of fire on ecosystems, as ecosystems differ in ecological and evolutionary relationships with fire. Our study focused on the four...

Modeling impacts of fire severity on successional trajectories and future fire behavior in Alaskan boreal forests

Treesearch

Jill F. Johnstone; T. Scott Rupp; Mark Olson; David. Verbyla

2011-01-01

Much of the boreal forest in western North America and Alaska experiences frequent, stand-replacing wildfires. Secondary succession after fire initiates most forest stands and variations in fire characteristics can have strong effects on pathways of succession. Variations in surface fire severity that influence whether regenerating forests are dominated by coniferous...

Chapter 6: Fire damage of wood structures

Treesearch

B. Kukay; R.H. White; F. Woeste

2012-01-01

Depending on the severity, fire damage can compromise the structural integrity of wood structures such as buildings or residences. Fire damage of wood structures can incorporate several models that address (1) the type, cause, and spread of the fire, (2) the thermal gradients and fire-resistance ratings, and (3) the residual load capacity (Figure 6.1). If there is a...

Monitoring post-fire recovery of shrublands in Mediterranean-type ecosystems using MODIS and TM/ETM+ data

NASA Astrophysics Data System (ADS)

Hope, Allen; Albers, Noah; Bart, Ryan

2010-05-01

Wildland fires in Mediterranean-Type Ecosystems (MTEs) are episodic events that dramatically alter land-cover conditions. Monitoring post-fire vegetation recovery is important for land management applications such as the scheduling of prescribed burns, post-fire resource management and soil erosion control. Full recovery of MTE shrublands may take many years and have a prolonged effect on water, energy and carbon fluxes in these ecosystems. Comparative studies of fynbos ecosystems in the Cape Floristic Region of South Africa (Western Cape Region) and chaparral ecosystems of California have demonstrated that there is a considerable degree of convergence in some aspects of post-fire vegetation regeneration and marked differences in other aspects. Since these MTEs have contrasting rainfall and soil nutrient conditions, an obvious question arises as to the similarity or dissimilarity in remotely sensed post-fire recovery pathways of vegetation stands in these two regions and the extent to which fire severity and drought impact the rate of vegetation recovery. Post-fire recovery pathways of chaparral and fynbos vegetation stands were characterized using the normalized difference vegetation index (NDVI) based on TM/ETM+ and MODIS (250 m) data. Procedures based on stands of unburned vegetation (control) were implemented to normalize the NDVI for variations associated with inter-annual differences in rainfall. Only vegetation stands that had not burned for 20 years were examined in this study to eliminate potential effects of variable fire histories on the recovery pathways. Post-fire recovery patterns of vegetation in both regions and across different vegetation types were found to be very similar. Post-fire stand age was the primary control over vegetation recovery and the NDVI returned to pre-fire values within seven to 10 years of the fires. Droughts were shown to cause slight interruptions in recovery rates while fire severity had no discernable effect. Intra-stand variability in the NDVI (pixel-scale) also returned to pre-fire values within the same time frame but increased with water stress associated with droughts. While these studies indicated that the NDVI of fynbos and chaparral stands recovered to pre-fire values within 10 years, it is recognized that other ecosystem characteristics may take considerably longer to recover. Despite the larger pixel size, MODIS data were found to be more suitable for monitoring vegetation post-fire recovery than TM/ETM+ data, requiring considerably less pre-processing and providing substantially more information regarding phenological characteristics of recovery pathways. Future studies will include consideration of fire history in the post-fire recovery characteristics of vegetation in these two MTEs.

Acacia shrubs respond positively to high severity wildfire: Implications for conservation and fuel hazard management.

PubMed

Gordon, Christopher E; Price, Owen F; Tasker, Elizabeth M; Denham, Andrew J

2017-01-01

High severity wildfires pose threats to human assets, but are also perceived to impact vegetation communities because a small number of species may become dominant immediately after fire. However there are considerable gaps in our knowledge about species-specific responses of plants to different fire severities, and how this influences fuel hazard in the short and long-term. Here we conduct a floristic survey at sites before and two years after a wildfire of unprecedented size and severity in the Warrumbungle National Park (Australia) to explore relationships between post-fire growth of a fire responsive shrub genera (Acacia), total mid-story vegetation cover, fire severity and fuel hazard. We then survey 129 plots surrounding the park to assess relationships between mid-story vegetation cover and time-since-fire. Acacia species richness and cover were 2.3 and 4.3 times greater at plots after than before the fire. However the same common dominant species were present throughout the study. Mid-story vegetation cover was 1.5 times greater after than before the wildfire, and Acacia species contribution to mid-story cover increased from 10 to 40%. Acacia species richness was not affected by fire severity, however strong positive associations were observed between Acacia and total mid-story vegetation cover and severity. Our analysis of mid-story vegetation recovery showed that cover was similarly high between 2 and 30years post-fire, then decreased until 52years. Collectively, our results suggest that Acacia species are extremely resilient to high severity wildfire and drive short to mid-term increases in fuel hazard. Our results are discussed in relation to fire regime management from the twin perspectives of conserving biodiversity and mitigating human losses due to wildfire. Copyright © 2016 Elsevier B.V. All rights reserved.

Potential postwildfire debris-flow hazards - A prewildfire evaluation for the Jemez Mountains, north-central New Mexico

Treesearch

Anne C. Tillery; Jessica Haas

2016-01-01

Wildfire can substantially increase the probability of debris flows, a potentially hazardous and destructive form of mass wasting, in landscapes that have otherwise been stable throughout recent history. Although the exact location, extent, and severity of wildfire or subsequent rainfall intensity and duration cannot be known, probabilities of fire and debris‑flow...

Application of wildfire spread and behavior models to assess fire probability and severity in the Mediterranean region

NASA Astrophysics Data System (ADS)

Salis, Michele; Arca, Bachisio; Bacciu, Valentina; Spano, Donatella; Duce, Pierpaolo; Santoni, Paul; Ager, Alan; Finney, Mark

2010-05-01

Characterizing the spatial pattern of large fire occurrence and severity is an important feature of the fire management planning in the Mediterranean region. The spatial characterization of fire probabilities, fire behavior distributions and value changes are key components for quantitative risk assessment and for prioritizing fire suppression resources, fuel treatments and law enforcement. Because of the growing wildfire severity and frequency in recent years (e.g.: Portugal, 2003 and 2005; Italy and Greece, 2007 and 2009), there is an increasing demand for models and tools that can aid in wildfire prediction and prevention. Newer wildfire simulation systems offer promise in this regard, and allow for fine scale modeling of wildfire severity and probability. Several new applications has resulted from the development of a minimum travel time (MTT) fire spread algorithm (Finney, 2002), that models the fire growth searching for the minimum time for fire to travel among nodes in a 2D network. The MTT approach makes computationally feasible to simulate thousands of fires and generate burn probability and fire severity maps over large areas. The MTT algorithm is imbedded in a number of research and fire modeling applications. High performance computers are typically used for MTT simulations, although the algorithm is also implemented in the FlamMap program (www.fire.org). In this work, we described the application of the MTT algorithm to estimate spatial patterns of burn probability and to analyze wildfire severity in three fire prone areas of the Mediterranean Basin, specifically Sardinia (Italy), Sicily (Italy) and Corsica (France) islands. We assembled fuels and topographic data for the simulations in 500 x 500 m grids for the study areas. The simulations were run using 100,000 ignitions under weather conditions that replicated severe and moderate weather conditions (97th and 70th percentile, July and August weather, 1995-2007). We used both random ignition locations and ignition probability grids (1000 x 1000 m) built from historical fire data (1995-2007). The simulation outputs were then examined to understand relationships between burn probability and specific vegetation types and ignition sources. Wildfire threats to specific values of human interest were quantified to map landscape patterns of wildfire risk. The simulation outputs also allowed us to differentiate between areas of the landscape that were progenitors of fires versus "victims" of large fires. The results provided spatially explicit data on wildfire likelihood and intensity that can be used in a variety of strategic and tactical planning forums to mitigate wildfire threats to human and other values in the Mediterranean Basin.

Wood utilization

Treesearch

Eugene M. Wengert; Dennis M. Donnelly; Donald C. Markstrom; Harold E. Worth

1985-01-01

In the past, markets for quaking aspen timber from the Rocky Mountains have been insufficient to support significant harvesting. This shortage of markets severely restrained the potential for aspen management. As a result, many stands protected from wildfire gradually reverted to conifers (see the VEGETATIVE REGENERATION and FIRE chapters).

Fire and the distribution and uncertainty of carbon sequestered as above-ground tree biomass in Yosemite and Sequoia & Kings Canyon National Parks

USGS Publications Warehouse

Lutz, James A.; Matchett, John R.; Tarnay, Leland W.; Smith, Douglas F.; Becker, Kendall M.L.; Furniss, Tucker J.; Brooks, Matthew L.

2017-01-01

Fire is one of the principal agents changing forest carbon stocks and landscape level distributions of carbon, but few studies have addressed how accurate carbon accounting of fire-killed trees is or can be. We used a large number of forested plots (1646), detailed selection of species-specific and location-specific allometric equations, vegetation type maps with high levels of accuracy, and Monte Carlo simulation to model the amount and uncertainty of aboveground tree carbon present in tree species (hereafter, carbon) within Yosemite and Sequoia & Kings Canyon National Parks. We estimated aboveground carbon in trees within Yosemite National Park to be 25 Tg of carbon (C) (confidence interval (CI): 23–27 Tg C), and in Sequoia & Kings Canyon National Park to be 20 Tg C (CI: 18–21 Tg C). Low-severity and moderate-severity fire had little or no effect on the amount of carbon sequestered in trees at the landscape scale, and high-severity fire did not immediately consume much carbon. Although many of our data inputs were more accurate than those used in similar studies in other locations, the total uncertainty of carbon estimates was still greater than ±10%, mostly due to potential uncertainties in landscape-scale vegetation type mismatches and trees larger than the ranges of existing allometric equations. If carbon inventories are to be meaningfully used in policy, there is an urgent need for more accurate landscape classification methods, improvement in allometric equations for tree species, and better understanding of the uncertainties inherent in existing carbon accounting methods.

Minimization of Roll Firings for Optimal Propellant Maneuvers

NASA Astrophysics Data System (ADS)

Leach, Parker C.

Attitude control of the International Space Station (ISS) is critical for operations, impacting power, communications, and thermal systems. The station uses gyroscopes and thrusters for attitude control, and reorientations are normally assisted by thrusters on docked vehicles. When the docked vehicles are unavailable, the reduction in control authority in the roll axis results in frequent jet firings and massive fuel consumption. To improve this situation, new guidance and control schemes are desired that provide control with fewer roll firings. Optimal control software was utilized to solve for potential candidates that satisfied desired conditions with the goal of minimizing total propellant. An ISS simulation too was then used to test these solutions for feasibility. After several problem reformulations, multiple candidate solutions minimizing or completely eliminating roll firings were found. Flight implementation would not only save massive amounts of fuel and thus money, but also reduce ISS wear and tear, thereby extending its lifetime.

Avifaunal responses to fire in southwestern montane forests along a burn severity gradient

Treesearch

Natasha B. Kotliar; Patricia L. Kennedy; Kimberly Ferree

2007-01-01

The effects of burn severity on avian communities are poorly understood, yet this information is crucial to fire management programs. To quantify avian response patterns along a burn severity gradient, we sampled 49 random plots (2001-2002) at the 17351-ha Cerro Grande Fire (2000) in New Mexico, USA. Additionally, pre-fire avian surveys (1986- 1988, 1990) created a...

Average stand age from forest inventory plots does not describe historical fire regimes in ponderosa pine and mixed-conifer forests of western North America

Treesearch

Jens T. Stevens; Hugh D. Safford; Malcolm P. North; Jeremy S. Fried; Andrew N. Gray; Peter M. Brown; Christopher R. Dolanc; Solomon Z. Dobrowski; Donald A. Falk; Calvin A. Farris; Jerry F. Franklin; Peter Z. Fulé; R. Keala Hagmann; Eric E. Knapp; Jay D. Miller; Douglas F. Smith; Thomas W. Swetnam; Alan H. Taylor; Julia A. Jones

2016-01-01

Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests...

Pre-wildfire management treatments interact with fire severity to have lasting effects on post-wildfire vegetation response

Treesearch

Kristen L. Shive; Carolyn H. Sieg; Peter Z. Fule

2013-01-01

Land managers are routinely applying fuel reduction treatments to mitigate the risk of severe, stand-replacing fire in ponderosa pine communities of the southwestern US. When these treatments are burned by wildfire they generally reduce fire severity, but less is known about how they influence post-wildfire vegetation recovery, as compared to pre-fire untreated areas....

A project for monitoring trends in burn severity

USGS Publications Warehouse

Eidenshink, Jeffery C.; Schwind, Brian; Brewer, Ken; Zhu, Zhu-Liang; Quayle, Brad; Howard, Stephen M.

2007-01-01

Jeff Eidenshink, Brian Schwind, Ken Brewer, Zhi-Liang Zhu, Brad Quayle, and Elected officials and leaders of environmental agencies need information about the effects of large wildfires in order to set policy and make management decisions. Recently, the Wildland Fire Leadership Council (WFLC), which implements and coordinates the National Fire Plan (NFP) and Federal Wildland Fire Management Policies (National Fire Plan 2004), adopted a strategy to monitor the effectiveness of the National Fire Plan and the Healthy Forests Restoration Act (HFRA). One component of this strategy is to assess the environmental impacts of large wildland fires and identify the trends of burn severity on all lands across the United States. To that end, WFLC has sponsored a six-year project, Monitoring Trends in Burn Severity (MTBS), which requires the U.S. Department of Agriculture Forest Service (USDA-FS) and the U.S. Geological Survey (USGS) to map and assess the burn severity for all large current and historical fires. Using Landsat data and the differenced Normalized Burn Ratio (dNBR) algorithm, the USGS Center for Earth Resources Observation and Science (EROS) and USDA-FS Remote Sensing Applications Center will map burn severity of all fires since 1984 greater than 202 ha (500ac) in the east, and 404 ha (1,000 ac) in the west. The number of historical fires from this period combined with current fires occurring during the course of the project will exceed 9,000. The MTBS project will generate burn severity data, maps, and reports, which will be available for use at local, state, and national levels to evaluate trends in burn severity and help develop and assess the effectiveness of land management decisions. Additionally, the information developed will provide a baseline from which to monitor the recovery and health of fire-affected landscapes over time. Spatial and tabular data quantifying burn severity will augment existing information used to estimate risk associated with a range of current and future resource threats. The annual report of 2004 fires has been completed. All data and results will be distributed to the public on a Web site. A Project for Monitoring Trends in Burn Severity

Initial segment Kv2.2 channels mediate a slow delayed rectifier and maintain high frequency action potential firing in medial nucleus of the trapezoid body neurons

PubMed Central

Johnston, Jamie; Griffin, Sarah J; Baker, Claire; Skrzypiec, Anna; Chernova, Tatanya; Forsythe, Ian D

2008-01-01

The medial nucleus of the trapezoid body (MNTB) is specialized for high frequency firing by expression of Kv3 channels, which minimize action potential (AP) duration, and Kv1 channels, which suppress multiple AP firing, during each calyceal giant EPSC. However, the outward K+ current in MNTB neurons is dominated by another unidentified delayed rectifier. It has slow kinetics and a peak conductance of ∼37 nS; it is half-activated at −9.2 ± 2.1 mV and half-inactivated at −35.9 ± 1.5 mV. It is blocked by several non-specific potassium channel antagonists including quinine (100 μm) and high concentrations of extracellular tetraethylammonium (TEA; IC50 = 11.8 mm), but no specific antagonists were found. These characteristics are similar to recombinant Kv2-mediated currents. Quantitative RT-PCR showed that Kv2.2 mRNA was much more prevalent than Kv2.1 in the MNTB. A Kv2.2 antibody showed specific staining and Western blots confirmed that it recognized a protein ∼110 kDa which was absent in brainstem tissue from a Kv2.2 knockout mouse. Confocal imaging showed that Kv2.2 was highly expressed in axon initial segments of MNTB neurons. In the absence of a specific antagonist, Hodgkin–Huxley modelling of voltage-gated conductances showed that Kv2.2 has a minor role during single APs (due to its slow activation) but assists recovery of voltage-gated sodium channels (Nav) from inactivation by hyperpolarizing interspike potentials during repetitive AP firing. Current-clamp recordings during high frequency firing and characterization of Nav inactivation confirmed this hypothesis. We conclude that Kv2.2-containing channels have a distinctive initial segment location and crucial function in maintaining AP amplitude by regulating the interspike potential during high frequency firing. PMID:18511484

Using satellite fire detection to calibrate components of the fire weather index system in Malaysia and Indonesia.

PubMed

Dymond, Caren C; Field, Robert D; Roswintiarti, Orbita; Guswanto

2005-04-01

Vegetation fires have become an increasing problem in tropical environments as a consequence of socioeconomic pressures and subsequent land-use change. In response, fire management systems are being developed. This study set out to determine the relationships between two aspects of the fire problems in western Indonesia and Malaysia, and two components of the Canadian Forest Fire Weather Index System. The study resulted in a new method for calibrating components of fire danger rating systems based on satellite fire detection (hotspot) data. Once the climate was accounted for, a problematic number of fires were related to high levels of the Fine Fuel Moisture Code. The relationship between climate, Fine Fuel Moisture Code, and hotspot occurrence was used to calibrate Fire Occurrence Potential classes where low accounted for 3% of the fires from 1994 to 2000, moderate accounted for 25%, high 26%, and extreme 38%. Further problems arise when there are large clusters of fires burning that may consume valuable land or produce local smoke pollution. Once the climate was taken into account, the hotspot load (number and size of clusters of hotspots) was related to the Fire Weather Index. The relationship between climate, Fire Weather Index, and hotspot load was used to calibrate Fire Load Potential classes. Low Fire Load Potential conditions (75% of an average year) corresponded with 24% of the hotspot clusters, which had an average size of 30% of the largest cluster. In contrast, extreme Fire Load Potential conditions (1% of an average year) corresponded with 30% of the hotspot clusters, which had an average size of 58% of the maximum. Both Fire Occurrence Potential and Fire Load Potential calibrations were successfully validated with data from 2001. This study showed that when ground measurements are not available, fire statistics derived from satellite fire detection archives can be reliably used for calibration. More importantly, as a result of this work, Malaysia and Indonesia have two new sources of information to initiate fire prevention and suppression activities.

Implications of changing fire regimes for aquatic ecosystems

Treesearch

Bruce Rieman; Charles H. Luce; Jason B. Dunham; Amanda L. Rosenberger

2005-01-01

Climate change and past management, including fire suppression, have been linked to changing patterns of fire in the last century. It is widely believed that many forested areas have moved from a regime of low and mixed severity fire to more frequent and more continuous high severity fire (Hessburg and Agee 2003). There is growing concern among ecologists and natural...

Fire and weather disturbances in terrestrial ecosystems of the eastern Cascades.

Treesearch

James K. Agee

1994-01-01

Fire has been an important ecological process in eastside Cascade ecosystems for millennia. Fire regimes ranged from low severity to high severity, and historic fire return intervals ranged from less than a decade to greater than 300 years. Fire history and effects are described for grassland and shrubland ecosystems, and the range of forested communities by plant...

Climate, lightning ignitions, and fire severity in Yosemite National Park, California, USA

Treesearch

James A. Lutz; Jan W. van Wagtendonk; Andrea E. Thode; Jay D. Miller; Jerry F. Franklin

2009-01-01

Continental-scale studies of western North America have attributed recent increases in annual area burned and fire size to a warming climate, but these studies have focused on large fires and have left the issues of fire severity and ignition frequency unaddressed. Lightning ignitions, any of which could burn a large area given appropriate conditions for fire spread,...

Evaluation of weapons' combustion products in armored vehicles. Appendix C: Summary of descriptive statistics (proc tabulate). Appendix D: Summary of comparative statistics. Final report, 30 September 1986-14 December 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menzies, K.T.; Randel, M.A.; Quill, A.L.

1989-01-01

The U.S. Army Biomedical Research and Development Laboratory defined an extensive research program to address the generation of potentially toxic propellant combustion products in crew compartments of armored vehicles during weapons firing. The major objectives of the research were (1) to determine the presence and concentration of propellant combustion products, (2) to determine potential crew exposure to these combustion products, and (3) to assess the efficacy of field monitoring in armored vehicles. To achieve these goals, air monitoring was conducted in selected armored vehicle types, i.e., M109, M60, M3, M1, at several Army installations. Auxiliary information concerning the specific munitionsmore » fired and the Training and Doctrine Command (TRADOC) or Forces Command (FORSCOM) firing scenarios was collected so that a comparison of pollutant concentrations generated by specific weapons both within vehicle types and between vehicle types could be made.« less

BK Channels Are Required for Multisensory Plasticity in the Oculomotor System.

PubMed

Nelson, Alexandra B; Faulstich, Michael; Moghadam, Setareh; Onori, Kimberly; Meredith, Andrea; du Lac, Sascha

2017-01-04

Neural circuits are endowed with several forms of intrinsic and synaptic plasticity that could contribute to adaptive changes in behavior, but circuit complexities have hindered linking specific cellular mechanisms with their behavioral consequences. Eye movements generated by simple brainstem circuits provide a means for relating cellular plasticity to behavioral gain control. Here we show that firing rate potentiation, a form of intrinsic plasticity mediated by reductions in BK-type calcium-activated potassium currents in spontaneously firing neurons, is engaged during optokinetic reflex compensation for inner ear dysfunction. Vestibular loss triggers transient increases in postsynaptic excitability, occlusion of firing rate potentiation, and reductions in BK currents in vestibular nucleus neurons. Concurrently, adaptive increases in visually evoked eye movements rapidly restore oculomotor function in wild-type mice but are profoundly impaired in BK channel-null mice. Activity-dependent regulation of intrinsic excitability may be a general mechanism for adaptive control of behavioral output in multisensory circuits. Copyright © 2017 Elsevier Inc. All rights reserved.

Average Stand Age from Forest Inventory Plots Does Not Describe Historical Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America.

PubMed

Stevens, Jens T; Safford, Hugh D; North, Malcolm P; Fried, Jeremy S; Gray, Andrew N; Brown, Peter M; Dolanc, Christopher R; Dobrowski, Solomon Z; Falk, Donald A; Farris, Calvin A; Franklin, Jerry F; Fulé, Peter Z; Hagmann, R Keala; Knapp, Eric E; Miller, Jay D; Smith, Douglas F; Swetnam, Thomas W; Taylor, Alan H

Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the "stand age" variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age basal area in 58% of plots analyzed and more than 30% of pre-stand age basal area in 32% of plots, and 2) recruitment events are not necessarily related to high-severity fire occurrence. Because the FIA stand age variable is estimated from a sample of tree ages within the tree size class containing a plurality of canopy trees in the plot, it does not necessarily include the oldest trees, especially in uneven-aged stands. Thus, the FIA stand age variable does not indicate whether the trees in the predominant size class established in response to severe fire, or established during the absence of fire. FIA stand age was not designed to measure the time since a stand-replacing disturbance. Quantification of historical "mixed-severity" fire regimes must be explicit about the spatial scale of high-severity fire effects, which is not possible using FIA stand age data.

The use of remotely-sensed wildland fire radiation to infer the fates of carbon during biomass combustion - the need to understand and quantify a fire's mass and energy budget

NASA Astrophysics Data System (ADS)

Dickinson, M. B.; Dietenberger, M.; Ellicott, E. A.; Hardy, C.; Hudak, A. T.; Kremens, R.; Mathews, W.; Schroeder, W.; Smith, A. M.; Strand, E. K.

2016-12-01

Few measurement techniques offer broad-scale insight on the extent and characteristics of biomass combustion during wildland fires. Remotely-sensed radiation is one of these techniques but its measurement suffers from several limitations and, when quantified, its use to derive variables of real interest depends on an understanding of the fire's mass and energy budget. In this talk, we will review certain assumptions of wildland fire radiation measurement and explore the use of those measurements to infer the fates of biomass and the dissipation of combustion energy. Recent measurements show that the perspective of the sensor (nadir vs oblique) matters relative to estimates of fire radiated power. Other considerations for producing accurate estimates of fire radiation from remote sensing include obscuration by an intervening forest canopy and to what extent measurements that are based on the assumption of graybody/blackbody behavior underestimate fire radiation. Fire radiation measurements are generally a means of quantifying other variables and are often not of interest in and of themselves. Use of fire radiation measurements as a means of inference currently relies on correlations with variables of interest such as biomass consumption and sensible and latent heat and emissions fluxes. Radiation is an imperfect basis for these correlations in that it accounts for a minority of combustion energy ( 15-30%) and is not a constant as is often assumed. Measurements suggest that fire convective energy accounts for the majority of combustion energy and (after radiation) is followed by latent energy, soil heating, and pyrolysis energy, more or less in that order. Combustion energy in and of itself is not its potential maximum, but is reduced to an effective heat of combustion by combustion inefficiency and by work done to pyrolyze fuel (important in char production) and in moisture vaporization. The effective heat of combustion is often on the order of 65% of its potential maximum. Through consideration of available data and modeling, we conclude that there is substantial scope to improve the science behind fire radiation measurements and the inferences derived from those measurements.

Mediterranean maquis fuel model development and mapping to support fire modeling

NASA Astrophysics Data System (ADS)

Bacciu, V.; Arca, B.; Pellizzaro, G.; Salis, M.; Ventura, A.; Spano, D.; Duce, P.

2009-04-01

Fuel load data and fuel model maps represent a critical issue for fire spread and behaviour modeling. The availability of accurate input data at different spatial and temporal scales can allow detailed analysis and predictions of fire hazard and fire effects across a landscape. Fuel model data are used in spatially explicit fire growth models to attain fire behaviour information for fuel management in prescribed fires, fire management applications, firefighters training, smoke emissions, etc. However, fuel type characteristics are difficult to be parameterized due to their complexity and variability: live and dead materials with different size contribute in different ways to the fire spread and behaviour. In the last decades, a strong help was provided by the use of remote sensing imagery at high spatial and spectral resolution. Such techniques are able to capture fine scale fuel distributions for accurate fire growth projections. Several attempts carried out in Europe were devoted to fuel classification and map characterization. In Italy, fuel load estimation and fuel model definition are still critical issues to be addressed due to the lack of detailed information. In this perspective, the aim of the present work was to propose an integrated approach based on field data collection, fuel model development and fuel model mapping to provide fuel models for the Mediterranean maquis associations. Field data needed for the development of fuel models were collected using destructive and non destructive measurements in experimental plots located in Northern Sardinia (Italy). Statistical tests were used to identify the main fuel types that were classified into four custom fuel models. Subsequently, a supervised classification by the Maximum Likelihood algorithm was applied on IKONOS images to identify and map the different types of maquis vegetation. The correspondent fuel model was then associated to each vegetation type to obtain the fuel model map. The results show the potential of this approach in achieving a reasonable accuracy in fuel model development and mapping; fine scale fuel model maps can be potentially helpful to obtain realistic predictions of fire behaviour and fire effects.

Mapping the Distribution of Wildfire Fuels Using AVIRIS in the Santa Monica Mountains

NASA Technical Reports Server (NTRS)

Roberts, Dar; Gardner, M.; Regelbrugge, J.; Pedreros, D.; Ustin, S.

1998-01-01

Catastrophic wildfires, such as the 1990 Painted Cave Fire in Santa Barbara or Oakland fire of 1991, attest to the destructive potential of fire in the wildland/urban interface. For example, during the Painted Cave Fire, 673 structures were consumed over a period of only six hours at an estimated cost of 250 million dollars (Gomes et al., 1993). One of the primary sources of fuels is chaparral, which consists of plant species that are adapted to frequent fires and may actually promote its ignition and spread of through volatile organic compounds in foliage. As one of the most widely distributed plant communities in Southern California, and one of the most common vegetation types along the wildland urban interface, chaparral represents one of the greatest sources of wildfire hazard in the region. An ongoing NASA funded research project was initiated in 1994 to study the potential of AVIRIS for mapping wildfire fuel properties in Southern California chaparral. The project was initiated in the Santa Monica Mountains, an east-west trending range in western Los Angeles County that has experienced extremely high fire frequencies over the past 70 years. The Santa Monica Mountains were selected because they exemplify many of the problems facing the southwest, forming a complex mosaic of land ownership intermixed with a diversity of chaparral age classes and fuel loads. Furthermore, the area has a wide diversity of chaparral community types and a rich background in supporting geographic information including fire history, soils and topography. Recent fires in the Santa Monica Mountains, including several in 1993 and the Calabasas fire of 1996 attest to the active fire regime present in the area. The long term objectives of this project are to improve existing maps of wildland fuel properties in the area, link AVIRIS derived products to fuel models under development for the region, then predict fire hazard through models that simulate fire spread. In this paper, we describe the AVIRIS derived products we are developing to map wildland fuels.

Time-related changes in firing rates are influenced by recruitment threshold and twitch force potentiation in the first dorsal interosseous.

PubMed

Miller, Jonathan D; Herda, Trent J; Trevino, Michael A; Sterczala, Adam J; Ciccone, Anthony B

2017-08-01

What is the central question of this study? The influences of motor unit recruitment threshold and twitch force potentiation on the changes in firing rates during steady-force muscular contractions are not well understood. What is the main finding and its importance? The behaviour of motor units during steady force was influenced by recruitment threshold, such that firing rates decreased for lower-threshold motor units but increased for higher-threshold motor units. In addition, individuals with greater changes in firing rates possessed greater twitch force potentiation. There are contradictory reports regarding changes in motor unit firing rates during steady-force contractions. Inconsistencies are likely to be the result of previous studies disregarding motor unit recruitment thresholds and not examining firing rates on a subject-by-subject basis. It is hypothesized that firing rates are manipulated by twitch force potentiation during contractions. Therefore, in this study we examined time-related changes in firing rates at steady force in relationship to motor unit recruitment threshold in the first dorsal interosseous and the influence of twitch force potentiation on such changes in young versus aged individuals. Subjects performed a 12 s steady-force contraction at 50% maximal voluntary contraction, with evoked twitches before and after the contraction to quantify potentiation. Firing rates, in relationship to recruitment thresholds, were determined at the beginning, middle and end of the steady force. There were no firing rate changes for aged individuals. For the young, firing rates decreased slightly for lower-threshold motor units but increased for higher-threshold motor units. Twitch force potentiation was greater for young than aged subjects, and changes in firing rates were correlated with twitch force potentiation. Thus, individuals with greater increases in firing rates of higher-threshold motor units and decreases in lower-threshold motor units possessed greater twitch force potentiation. Overall, changes in firing rates during brief steady-force contractions are dependent on recruitment threshold and explained in part by twitch force potentiation. Given that firing rate changes were measured in relationship to recruitment threshold, this study illustrates a more complete view of firing rate changes during steady-force contractions. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Seedling performance covaries with dormancy thresholds: maintaining cryptic seed heteromorphism in a fire-prone system.

PubMed

Liyanage, Ganesha S; Ayre, David J; Ooi, Mark K J

2016-11-01

The production of morphologically different seeds or fruits by the same individual plant is known as seed heteromorphism. Such variation is expected to be selected for in disturbance-prone environments to allow germination into inherently variable regeneration niches. However, there are few demonstrations that heteromorphic seed characteristics should be favored by selection or how they may be maintained. In fire-prone ecosystems, seed heteromorphism is found in the temperatures needed to break physical dormancy, with seeds responding to high or low temperatures, ensuring emergence under variable fire-regime-related soil heating. Because of the relationship between dormancy-breaking temperature thresholds and fire severity, we hypothesize that different post-fire resource conditions have selected for covarying seedling traits, which contribute to maintenance of such heteromorphism. Seeds with low thresholds emerge into competitive conditions, either after low-severity fire or in vegetation gaps, and are therefore likely to experience selection for seedling characteristics that make them good competitors. On the other hand, high-temperature-threshold seeds would emerge into less competitive environments, indicative of stand-clearing high-severity fires, and would not experience the same selective forces. We identified high and low-threshold seed morphs via dormancy-breaking heat treatments and germination trials for two study species and compared seed mass and other morphological characteristics between morphs. We then grew seedlings from the two different morphs, with and without competition, and measured growth and biomass allocation as indicators of seedling performance. Seedlings from low-threshold seeds of both species performed better than their high-threshold counterparts, growing more quickly under competitive conditions, confirming that different performance can result from this seed characteristic. Seed mass or appearance did not differ between morphs, indicating that dormancy-breaking temperature threshold variation is a form of cryptic heteromorphism. The potential shown for the selective influence of different post-fire environmental conditions on seedling performance provides evidence of a mechanism for the maintenance of heteromorphic variation in dormancy-breaking temperature thresholds. © 2016 The Authors. Ecology, published by Wiley Periodicals, Inc., on behalf of the Ecological Society of America.

Factors controlling seedling germination after fire in Mediterranean gorse shrublands. Implications for fire prescription.

PubMed

De Luis, M; Raventós, J; González-Hidalgo, J C

2005-07-01

In Western Mediterranean areas, fires are frequent in forests established on old croplands where woody resprouting species are scarce and post-fire regeneration is limited to obligate-seeder species, such as Mediterranean gorse (Ulex parviflorus), that accumulate a great deal of fine dry fuel, increasing the risk of other severe fires. Under these conditions, fuel control techniques are required in order to prevent fires of high intensity and severity and the subsequent economic and ecological damage. Prescribed fires present an alternative to fuel control, and recent studies demonstrate that, under optimum climatic conditions, fire-line intensity values fall within the limits of those recommended for fire prescription. However, a better understanding of the consequences of fire on the regeneration of vegetation is needed in order to evaluate the suitability of prescribed fires as a technique for fuel reduction in Mediterranean gorse ecosystems. This paper analyses the factors controlling seedling germination after fire to make an evaluation from an ecological perspective of whether fire prescription is a suitable technique for fuel control in mature Mediterranean gorse shrublands. The results show that small differences in the composition of vegetation play a decisive role in fire behaviour, and have a decisive influence on the system's capacity for regeneration. Fire severity is low in mixed Mediterranean gorse communities with a low continuity of dead fine fuel (including Cistus sp., Rosmarinus sp., etc.) and fire creates a wide range of microhabitats where seedling emergence is high. In contrast, where U. parviflorus is more dominant, fire severity is higher and the regeneration of vegetation could be hindered. Our conclusions suggest that detailed studies of the composition of plant communities are required in order to decide whether prescribed burning should be applied.

Fire-induced erosion and millennial-scale climate change in northern ponderosa pine forests.

PubMed

Pierce, Jennifer L; Meyer, Grant A; Jull, A J Timothy

2004-11-04

Western US ponderosa pine forests have recently suffered extensive stand-replacing fires followed by hillslope erosion and sedimentation. These fires are usually attributed to increased stand density as a result of fire suppression, grazing and other land use, and are often considered uncharacteristic or unprecedented. Tree-ring records from the past 500 years indicate that before Euro-American settlement, frequent, low-severity fires maintained open stands. However, the pre-settlement period between about ad 1500 and ad 1900 was also generally colder than present, raising the possibility that rapid twentieth-century warming promoted recent catastrophic fires. Here we date fire-related sediment deposits in alluvial fans in central Idaho to reconstruct Holocene fire history in xeric ponderosa pine forests and examine links to climate. We find that colder periods experienced frequent low-severity fires, probably fuelled by increased understory growth. Warmer periods experienced severe droughts, stand-replacing fires and large debris-flow events that comprise a large component of long-term erosion and coincide with similar events in sub-alpine forests of Yellowstone National Park. Our results suggest that given the powerful influence of climate, restoration of processes typical of pre-settlement times may be difficult in a warmer future that promotes severe fires.

Seasonal Forecasting of Fires across Southern Borneo, 1997-2010

NASA Astrophysics Data System (ADS)

Spessa, Allan; Field, Robert; Kaiser, Johannes; Langner, Andreas; Moore, Jonathan; Pappenberger, Florian; Siegert, Florian; Weber, Ulrich

2014-05-01

Wildfire is a fundamental Earth System process, affecting almost all biogeochemical cycles, and all vegetated biomes. Fires are naturally rare in humid tropical forests, and tropical trees are generally killed by even low-intensity fires. However, fire activity in the tropics has increased markedly over the past 15-20 years, especially in Indonesia, Amazonia, and more recently, central Africa also. Since fire is the prime tool for clearing land in the tropics, it not surprising that the increase in fire activity is strongly associated with increased levels of deforestation, which is driven mainly by world-wide demand for timber and agricultural commodities. The consequences of deforestation fires for biodiversity conservation and emissions of greenhouse gases and aerosols are enormous. For example, carbon emissions from tropical biomass burning are around 20% of annual average global fossil fuel emissions. The destructive fires in Indonesia during the exceptionally strong El Niño-induced drought in late 1997 and early 1998 rank as some of the largest peak emissions events in recorded history. Past studies estimate about 1Gt of carbon was released to the atmosphere from the Indonesian fires in 1997 (which were mostly concentrated in carbon-rich forested peatlands). This amount is equivalent to about 14% of the average global annual fossil fuel emissions released during the 1990s. While not as large as the 1997-98 events, significant emissions from biomass burning have also been recorded in other (less severe) El Niño years across Indonesia, in particular, 2002, 2004, 2006 and 2009-2010. Recent climate modelling studies indicate that the frequency of El Niño events may increase under future climate change, affecting many tropical countries, including Indonesia. An increased drought frequency plus a projected increase in population and land use pressures in Indonesia, imply there will be even more fires and emissions in future across the region. However, while several studies using historical data have established negative relationships between fires and antecedent rainfall, and/or positive relationships between fires and deforestation in regions affected by El Nino, comparatively little work has attempted to predict fires and emissions in such regions. Ensemble seasonal climate forecasts issued with several months lead-time have been applied to support risk assessment systems in many fields, notably agricultural production and natural disaster management of flooding, heat waves, drought and fire. The USA, for example, has a long-standing seasonal fire danger prediction system. Fire danger monitoring systems have been operating in Indonesia for over a decade, but, as of yet, no fire danger prediction systems exist. Given the effort required to mobilise suppression and prevention measures in Indonesia, one could argue that high fire danger periods must be anticipated months in advance for mitigation and response measures to be effective. To address this need, the goal of our work was to examine the utility of seasonal rainfall forecasts in predicting severe fires in Indonesia more than one month in advance, using southern Borneo (comprising the bulk of Kalimantan) as a case study. Here we present the results of comparing seasonal forecasts of monthly rainfall from ECMWF's System 4 against i) observed rainfall (GPCP), and ii) burnt area and deforestation (MODIS, AVHRR and Landsat) across southern Borneo for the period 1997-2010. Our results demonstrate the utility of using ECMWF's seasonal climate forecasts for predicting fire activity in the region. Potential applications include improved fire mitigation and responsiveness, and improved risk assessments of biodiversity and carbon losses through fire. These are important considerations for forest protection programmes (e.g. REDD+), forest carbon markets and forest (re)insurance enterprises.

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

PubMed

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.

Modeling the effects of fire severity and spatial complexity on Small Mammals in Yosemite National Park, California

USGS Publications Warehouse

Roberts, Susan L.; Van Wagtendonk, Jan W.; Miles, A. Keith; Kelt, Douglas A.; Lutz, James A.

2008-01-01

We evaluated the impact of fire severity and related spatial and vegetative parameters on small mammal populations in 2 yr- to 15 yr-old burns in Yosemite National Park, California, USA. We also developed habitat models that would predict small mammal responses to fires of differing severity. We hypothesized that fire severity would influence the abundances of small mammals through changes in vegetation composition, structure, and spatial habitat complexity. Deer mouse (Peromyscus maniculatus) abundance responded negatively to fire severity, and brush mouse (P. boylii) abundance increased with increasing oak tree (Quercus spp.) cover. Chipmunk (Neotamias spp.) abundance was best predicted through a combination of a negative response to oak tree cover and a positive response to spatial habitat complexity. California ground squirrel (Spermophilus beecheyi) abundance increased with increasing spatial habitat complexity. Our results suggest that fire severity, with subsequent changes in vegetation structure and habitat spatial complexity, can influence small mammal abundance patterns.

Public health impacts of the severe haze in Equatorial Asia in September-October 2015: demonstration of a new framework for informing fire management strategies to reduce downwind smoke exposure

NASA Astrophysics Data System (ADS)

Koplitz, Shannon N.; Mickley, Loretta J.; Marlier, Miriam E.; Buonocore, Jonathan J.; Kim, Patrick S.; Liu, Tianjia; Sulprizio, Melissa P.; DeFries, Ruth S.; Jacob, Daniel J.; Schwartz, Joel; Pongsiri, Montira; Myers, Samuel S.

2016-09-01

In September-October 2015, El Niño and positive Indian Ocean Dipole conditions set the stage for massive fires in Sumatra and Kalimantan (Indonesian Borneo), leading to persistently hazardous levels of smoke pollution across much of Equatorial Asia. Here we quantify the emission sources and health impacts of this haze episode and compare the sources and impacts to an event of similar magnitude occurring under similar meteorological conditions in September-October 2006. Using the adjoint of the GEOS-Chem chemical transport model, we first calculate the influence of potential fire emissions across the domain on smoke concentrations in three receptor areas downwind—Indonesia, Malaysia, and Singapore—during the 2006 event. This step maps the sensitivity of each receptor to fire emissions in each grid cell upwind. We then combine these sensitivities with 2006 and 2015 fire emission inventories from the Global Fire Assimilation System (GFAS) to estimate the resulting population-weighted smoke exposure. This method, which assumes similar smoke transport pathways in 2006 and 2015, allows near real-time assessment of smoke pollution exposure, and therefore the consequent morbidity and premature mortality, due to severe haze. Our approach also provides rapid assessment of the relative contribution of fire emissions generated in a specific province to smoke-related health impacts in the receptor areas. We estimate that haze in 2015 resulted in 100 300 excess deaths across Indonesia, Malaysia and Singapore, more than double those of the 2006 event, with much of the increase due to fires in Indonesia’s South Sumatra Province. The model framework we introduce in this study can rapidly identify those areas where land use management to reduce and/or avoid fires would yield the greatest benefit to human health, both nationally and regionally.

Evaluating Greenhouse Gas Emissions Reporting Systems for Agricultural Waste Burning Using MODIS Active Fires

NASA Astrophysics Data System (ADS)

Lin, H.; Jin, Y.; Giglio, L.; Foley, J. A.; Randerson, J. T.

2010-12-01

Fires in agricultural ecosystems emit greenhouse gases and aerosols that influence climate on multiple spatial and temporal scales. Annex 1 countries of the United Nations Framework Convention on Climate Change (UNFCCC), many of which ratified the Kyoto Protocol, are required to report emissions of CO2, CH4 and N2O from these fires annually. We evaluated several aspects of this reporting system, including the optimality of the crops targeted by the UNFCCC globally and within Annex 1 countries and the consistency of emissions reporting among countries. We also evaluated the success of the individual countries in capturing interannual variability and long-term trends in agricultural fire activity. We combined global crop maps with Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) active fire detections. At a global scale, we recommend adding ground nuts, cocoa, cotton and oil palm, and removing potato, oats, pulse other and rye from the UNFCCC list of 14 crops. This leads to an overall increase of 6% of the active fires covered by the reporting system. Optimization led to a different recommended list for Annex 1 countries. Extending emissions reporting to all Annex 1 countries (from the current set of 19 countries) would increase the efficacy of the reporting system from 10% to 20%, and further including several non-Annex 1 countries (Argentina, Brazil, China, India, Indonesia, Thailand, Kazakhstan, Mexico and Nigeria) would capture over 58% of active fires in croplands worldwide. Analyses of interannual trends from the U.S. and Australia showed the importance of both intensity of fire use and crop production in controlling year-to-year variations in agricultural fire emissions. Remote sensing provides an efficient tool for an independent assessment of current UNFCCC emissions reporting system; and, if combined with census data, field experiments and expert opinion, has the potential for improving the robustness of the next generation inventory system.

Climate, fire size, and biophysical setting control fire severity and spatial pattern in the northern Cascade Range, USA

Treesearch

C. Alina Cansler; Donald. McKenzie

2014-01-01

Warmer and drier climate over the past few decades has brought larger fire sizes and increased annual area burned in forested ecosystems of western North America, and continued increases in annual area burned are expected due to climate change. As warming continues, fires may also increase in severity and produce larger contiguous patches of severely burned areas. We...

Predicting hydrological and erosional risks in fire-affected watersheds: recent advances and research gaps

NASA Astrophysics Data System (ADS)

Nunes, João Pedro; Keizer, Jan Jacob

2017-04-01

Models can be invaluable tools to assess and manage the impacts of forest fires on hydrological and erosion processes. Immediately after fires, models can be used to identify priority areas for post-fire interventions or assess the risks of flooding and downstream contamination. In the long term, models can be used to evaluate the long-term implications of a fire regime for soil protection, surface water quality and potential management risks, or determine how changes to fire regimes, caused e.g. by climate change, can impact soil and water quality. However, several challenges make post-fire modelling particularly difficult: • Fires change vegetation cover and properties, such as by changing soil water repellency or by adding an ash layer over the soil; these processes, however are not described in currently used models, so that existing models need to be modified and tested. • Vegetation and soils recover with time since fire, changing important model parameters, so that the recovery processes themselves also need to be simulated, including the role of post-fire interventions. • During the window of vegetation and soil disturbance, particular weather conditions, such as the occurrence of severe droughts or extreme rainfall events, can have a large impact on the amount of runoff and erosion produced in burnt areas, so that models that smooth out these peak responses and rather simulate "long-term" average processes are less useful. • While existing models can simulate reasonable well slope-scale runoff generation and associated sediment losses and their catchment-scale routing, few models can accommodate the role of the ash layer or its transport by overland flow, in spite of its importance for soil fertility losses and downstream contamination. This presentation will provide an overview of the importance of post-fire hydrological and erosion modelling as well as of the challenges it faces and of recent efforts made to overcome these challenges. It will illustrate these challenges with two examples: probabilistic approaches to simulate the impact of different vegetation regrowth and post-fire climate combinations on runoff and erosion; and model developments for post-fire soil water repellency with different levels of complexity. It will also present an inventory of the current state-of-the-art and propose future research directions, both on post-fire models themselves and on their integration with other models in large-scale water resource assessment management.

Relevance of wildfires on dust emissions via interaction with near-surface wind pattern

NASA Astrophysics Data System (ADS)

Wagner, Robert; Jähn, Michael; Schepanski, Kerstin

2017-04-01

Mineral dust is a key player in the Earth system and shows diverse impacts on the radiation budget, cloud microphysics, marine and terrestrial ecosystems. Eventually, it also affects our modern way of life. Not only dust emissions from barren or unvegetated soil surfaces like deserts or uncultivated croplands are important sources of airborne mineral dust. Also, during fire events dust is entrained into the atmosphere and appears to contribute noteworthy to the atmospheric dust burden. The underlying process, which drives dust entrainment during fires, is the so-called pyro-convection. The high temperatures in the center of a fire result in an upward motion of the heated air. Subsequently, air flows towards the fire replacing the raising air. The resulting accelerated winds are able to mobilize soil and dust particles up to a size of several millimeters, depending of both the size and the strength of the fire. Several measurements have shown that up to 80% of the mass fraction of the emitted particles during natural or prescribed fires is related to soil or dust particles. The particles are then mixed externally with the combustion aerosols into the convective updraft and were finally inject into altitudes above the planetary boundary layer where they can be distributed and transported over long distances by the atmospheric circulation. To investigate the impacts of such fires on the near-surface wind pattern and the potential for dust emissions via exceeding typical threshold velocities, high resolved Large-Eddy Simulations (LES) with the All Scale Atmospheric Model (ASAM) were executed. In the framework of this study, the influences of different fire properties (fire intensity, size, and shape) and different atmospheric conditions on the strength and extent of fire-related winds and finally their relevance for dust emissions were investigated using sensitivity studies. Prescribed fires are omnipresent during dry seasons and pyro-convection is a mechanism entraining dust particles into boundary layer. As the quantity of dust emitted during fire events is still unclear, the results presented here will support the development of a parameterization of fire-related dust entrainment for meso-scale models. This will allow an estimation of such fire-related dust emissions on a continental scale and can finally reduce the uncertainty in the aerosol-climate feedback.

Mega-fire Recovery in Dry Conifer Forests of the Interior West

NASA Astrophysics Data System (ADS)

Malone, S. L.; Fornwalt, P.; Chambers, M. E.; Battaglia, M.

2015-12-01

Wildfire is a complex landscape process with great uncertainty in whether trends in size and severity are shifting trajectories for ecosystem recovery that are outside of the historical range of variability. Considering that wildfire size and severity is likely to increase into the future with a drier climate, it is important that we understand wildfire effects and ecosystem recovery. To evaluate how ecosystems recover from wildfire we measured spatial patterns in regeneration and mapped tree refugia within mega-fire perimeters (Hayman, Jasper, Bobcat, and Grizzly Gulch) in ponderosa pine (Pinus ponderosa) dominated forest. On average, high severity fire effects accounted for > 15% of burned area and increased with fire size. Areas with high severity fire effects contained 1 - 15% tree refugia cover, compared to 37 - 70% observed in low severity areas . Large high severity patches with low coverage of tree refugia, were more frequent in larger fires and regeneration distances required to initiate forest recovery far exceeded 1.5 canopy height or 200 m, distances where the vast majority of regeneration is likely to arise. Using a recovery model driven by distance, we estimate recovery times between 300 to > 1000 years for these mega-fires. In Western dry conifer forests, large patches of stand replacing fire are likely to lead to uneven aged forest and very long recovery times.

Analysis of the ability of large-scale reanalysis data to define Siberian fire danger in preparation for future fire prediction

NASA Astrophysics Data System (ADS)

Soja, Amber; Westberg, David; Stackhouse, Paul, Jr.; McRae, Douglas; Jin, Ji-Zhong; Sukhinin, Anatoly

2010-05-01

Fire is the dominant disturbance that precipitates ecosystem change in boreal regions, and fire is largely under the control of weather and climate. Fire frequency, fire severity, area burned and fire season length are predicted to increase in boreal regions under current climate change scenarios. Therefore, changes in fire regimes have the potential to compel ecological change, moving ecosystems more quickly towards equilibrium with a new climate. The ultimate goal of this research is to assess the viability of large-scale (1°) data to be used to define fire weather danger and fire regimes, so that large-scale data can be confidently used to predict future fire regimes using large-scale fire weather data, like that available from current Intergovernmental Panel on Climate Change (IPCC) climate change scenarios. In this talk, we intent to: (1) evaluate Fire Weather Indices (FWI) derived using reanalysis and interpolated station data; (2) discuss the advantages and disadvantages of using these distinct data sources; and (3) highlight established relationships between large-scale fire weather data, area burned, active fires and ecosystems burned. Specifically, the Canadian Forestry Service (CFS) Fire Weather Index (FWI) will be derived using: (1) NASA Goddard Earth Observing System version 4 (GEOS-4) large-scale reanalysis and NASA Global Precipitation Climatology Project (GPCP) data; and National Climatic Data Center (NCDC) surface station-interpolated data. Requirements of the FWI are local noon surface-level air temperature, relative humidity, wind speed, and daily (noon-noon) rainfall. GEOS-4 reanalysis and NCDC station-interpolated fire weather indices are generally consistent spatially, temporally and quantitatively. Additionally, increased fire activity coincides with increased FWI ratings in both data products. Relationships have been established between large-scale FWI to area burned, fire frequency, ecosystem types, and these can be use to estimate historic and future fire regimes.

Extreme Wildfire Spread and Behaviour: Case Studies from North Sardinia, Italy

NASA Astrophysics Data System (ADS)

Salis, M.; Arca, B.; Ager, A.; Fois, C.; Bacciu, V.; Duce, P.; Spano, D.

2012-04-01

Worldwide, fire seasons are usually characterized by the occurrence of one or more days with extreme environmental conditions, such as heat waves associated with strong winds. On these days, fires can quickly get out of hand originating large and severe wildfires. In these cases, containment and extinguishment phases are critical, considering that the imperative goal is to keep fire crews, people and animals safe. In this work we will present a set of large and severe wildfires occurred with extreme environmental conditions in the northern area of Sardinia. The most recent wildfire we will describe was ignited on July 13, 2011 in the Oschiri municipality (40°43' N; 9°06' E), and burned about 2,500 ha of wooded and herbaceous pastures and oakwoods in few hours. The second wildfire we will present was ignited on July 23, 2009 in the Bonorva municipality (40°25' N; 8° 46' E), and was responsible for the death of two people and several damages to houses, animals and farms. This wildfire lasted on July 25, and burned about 10,000 ha of wooded and herbaceous pastures; the most of the area was burned during the first day. The last wildfire we will describe was ignited on July 23, 2007 in the Oniferi municipality (40°16' N; 9° 16' E) and burned about 9,000 ha of wooded and herbaceous pastures and oakwoods; about 8,000 ha were burned after 11 hours of propagation. All these wildfires were ignited in days characterized by very hot temperatures associated to the effect of air masses moving from inland North Africa to the Mediterranean Basin, and strong winds from west-south west. This is one of the typical weather pattern associated with large and severe wildfires in North Sardinia, and is well documented in the last years. Weather conditions, fuels and topography factors related to each case study will be accurately analyzed. Moreover, a detailed overview of observed fire spread and behavior and post-fire vegetation recovery will be presented. The fire spread and behavior data collected during the events will be also compared with the results obtained with FARSITE (Finney, 1994) and FLAMMAP (Finney, 2003) models. The main goal of this paper is to thoroughly describe the fire behavior of relevant and recent case studies, in order to learn from it and lessen the chance of making potential mistakes or hazardous firefighting operations in the same environmental conditions. Furthermore, a crucial point is to teach and prepare people and fire crews not to be surprised by severe or abrupt fire behavior under extreme environmental conditions. For these reasons, the combination of analysis, knowledge and awareness of historical case studies, field experience and computer modeling represent a key learning technique.

Effects of fire damage on the structural properties of steel bridge elements.

DOT National Transportation Integrated Search

2011-04-30

It is well known that fire can cause severe damage to steel bridges. There are documented cases where fire has directly led to the collapse or significant sagging of a steel bridge. However, when the damage is less severe, the effects of the fire, if...

ELECTROPHYSIOLOGY OF ELECTRIC ORGAN IN GYMNOTUS CARAPO

PubMed Central

Bennett, Michael V. L.; Grundfest, Harry

1959-01-01

The electric organ of G. carapo is formed by linearly arrayed electroplaques which lie in four tubes on each side of the fish. In one tube the electroplaques are innervated on their rostral surfaces, in the others on the caudal. Both surfaces of each electroplaque produce spikes, and either can be excited alone by a suitably oriented externally applied stimulating current. The innervated surface, however, has a lower threshold, and in the normal organ activity, which is a continuous discharge at 35 to 60/sec., it is always fired first by the large neurally evoked postsynaptic potential. The spike of the innervated face then fires the opposite face. The potential recorded external to the innervated face is initially negative and becomes positive when the other face fires. The potential outside the other face is inverted. The p.s.p.'s are electrically inexcitable, have short duration, and are augmented by hyperpolarization. A single electroplaque is innervated by several nerve fibers, which produce summative p.s.p.'s. Homosynaptic facilitation of p.s.p.'s is common. The synapses are cholinoceptive. The organ discharge begins with synchronized activity in the rostrally innervated electroplaques. After a brief interval, the electroplaques in the other three tubes fire. The organ discharge therefore is triphasic, resulting from the summation of the two diphasic components that are oppositely directed and asynchronous. Observations on the sensory role of the organ are included. PMID:13654750

Landscape variation in tree regeneration and snag fall drive fuel loads in 24-year old post-fire lodgepole pine forests.

PubMed

Nelson, Kellen N; Turner, Monica G; Romme, William H; Tinker, Daniel B

2016-12-01

Escalating wildfire in subalpine forests with stand-replacing fire regimes is increasing the extent of early-seral forests throughout the western USA. Post-fire succession generates the fuel for future fires, but little is known about fuel loads and their variability in young post-fire stands. We sampled fuel profiles in 24-year-old post-fire lodgepole pine (Pinus contorta var. latifolia) stands (n = 82) that regenerated from the 1988 Yellowstone Fires to answer three questions. (1) How do canopy and surface fuel loads vary within and among young lodgepole pine stands? (2) How do canopy and surface fuels vary with pre- and post-fire lodgepole pine stand structure and environmental conditions? (3) How have surface fuels changed between eight and 24 years post-fire? Fuel complexes varied tremendously across the landscape despite having regenerated from the same fires. Available canopy fuel loads and canopy bulk density averaged 8.5 Mg/ha (range 0.0-46.6) and 0.24 kg/m 3 (range: 0.0-2.3), respectively, meeting or exceeding levels in mature lodgepole pine forests. Total surface-fuel loads averaged 123 Mg/ha (range: 43-207), and 88% was in the 1,000-h fuel class. Litter, 1-h, and 10-h surface fuel loads were lower than reported for mature lodgepole pine forests, and 1,000-h fuel loads were similar or greater. Among-plot variation was greater in canopy fuels than surface fuels, and within-plot variation was greater than among-plot variation for nearly all fuels. Post-fire lodgepole pine density was the strongest positive predictor of canopy and fine surface fuel loads. Pre-fire successional stage was the best predictor of 100-h and 1,000-h fuel loads in the post-fire stands and strongly influenced the size and proportion of sound logs (greater when late successional stands had burned) and rotten logs (greater when early successional stands had burned). Our data suggest that 76% of the young post-fire lodgepole pine forests have 1,000-h fuel loads that exceed levels associated with high-severity surface fire potential, and 63% exceed levels associated with active crown fire potential. Fire rotations in Yellowstone National Park are predicted to shorten to a few decades and this prediction cannot be ruled out by a lack of fuels to carry repeated fires. © 2016 by the Ecological Society of America.

Continued warming could transform Greater Yellowstone fire regimes by mid-21st century

PubMed Central

Westerling, Anthony L.; Turner, Monica G.; Smithwick, Erica A. H.; Romme, William H.; Ryan, Michael G.

2011-01-01

Climate change is likely to alter wildfire regimes, but the magnitude and timing of potential climate-driven changes in regional fire regimes are not well understood. We considered how the occurrence, size, and spatial location of large fires might respond to climate projections in the Greater Yellowstone ecosystem (GYE) (Wyoming), a large wildland ecosystem dominated by conifer forests and characterized by infrequent, high-severity fire. We developed a suite of statistical models that related monthly climate data (1972–1999) to the occurrence and size of fires >200 ha in the northern Rocky Mountains; these models were cross-validated and then used with downscaled (∼12 km × 12 km) climate projections from three global climate models to predict fire occurrence and area burned in the GYE through 2099. All models predicted substantial increases in fire by midcentury, with fire rotation (the time to burn an area equal to the landscape area) reduced to <30 y from the historical 100–300 y for most of the GYE. Years without large fires were common historically but are expected to become rare as annual area burned and the frequency of regionally synchronous fires increase. Our findings suggest a shift to novel fire–climate–vegetation relationships in Greater Yellowstone by midcentury because fire frequency and extent would be inconsistent with persistence of the current suite of conifer species. The predicted new fire regime would transform the flora, fauna, and ecosystem processes in this landscape and may indicate similar changes for other subalpine forests. PMID:21788495

Assessment of fire effects based on Forest Inventory and Analysis data and a long-term fire mapping data set

Treesearch

John D. Shaw; Sara A. Goeking; James Menlove; Charles E. Werstak

2017-01-01

Integration of Forest Inventory and Analysis (FIA) plot data with Monitoring Trends in Burn Severity (MTBS) data can provide new information about fire effects on forests. This integration allowed broad-scale assessment of the cover types burned in large fires, the relationship between prefire stand conditions and fire severity, and postfire stand conditions. Of the 42...

Stand-replacing patches within a ‘mixed severity’ fire regime: quantitative characterization using recent fires in a long-established natural fire area

Treesearch

B.M. Collins; S.L. Stephens

2010-01-01

The complexity inherent in variable, or mixed-severity fire regimes makes quantitative characterization of important fire regime attributes (e.g., proportion of landscape burned at different severities, size and distribution of stand-replacing patches) difficult. As a result, there is ambiguity associated with the term ‘mixed-severity’. We address...

A new forest fire paradigm: The need for high-severity fires

Treesearch

Monica L. Bond; Rodney B. Siegel; Richard L. Hutto; Victoria A. Saab; Stephen A. Shunk

2012-01-01

Bond, Monica L.; Siegel, Rodney B.; Hutto, Richard L.; Saab, Victoria A.; Shunk, Stephen A. 2012. A new forest fire paradigm: The need for high-severity fires. The Wildlife Professional. Winter 2012: 46-49. During the 2012 fire season from June through August, wildfires in the drought-stricken western and central United States burned more than 3.6 million acres of...

Bird communities following high-severity fire: Response to single and repeat fires in a mixed-evergreen forest, Oregon, USA

Treesearch

Joseph B. Fontaine; Daniel C. Donato; W. Douglas Robinson; Beverly E. Law; J. Boone Kauffman

2009-01-01

Fire is a widespread natural disturbance agent in most conifer-dominated forests. In light of climate change and the effects of fire exclusion, single and repeated high-severity (stand-replacement) fires have become prominent land management issues. We studied bird communities using point counting in the Klamath-Siskiyou ecoregion of Oregon, USA at various points in...

Variation in fire regimes of the Rocky Mountains: Implications for avian communities and fire management

USGS Publications Warehouse

Saab, Victoria A.; Powell, Hugo D.W.; Kotliar, Natasha B.; Newlon, Karen R.; Saab, Victoria A.; Powell, Hugo D.W.

2005-01-01

Information about avian responses to fire in the U.S. Rocky Mountains is based solely on studies of crown fires. However, fire management in this region is based primarily on studies of low-elevation ponderosa pine (Pinus ponderosa) forests maintained largely by frequent understory fires. In contrast to both of these trends, most Rocky Mountain forests are subject to mixed severity fire regimes. As a result, our knowledge of bird responses to fire in the region is incomplete and skewed toward ponderosa pine forests. Research in recent large wildfires across the Rocky Mountains indicates that large burns support diverse avifauna. In the absence of controlled studies of bird responses to fire, we compared reproductive success for six cavity-nesting species using results from studies in burned and unburned habitats. Birds in ponderosa pine forests burned by stand-replacement fire tended to have higher nest success than individuals of the same species in unburned habitats, but unburned areas are needed to serve species dependent upon live woody vegetation, especially foliage gleaners. Over the last century, fire suppression, livestock grazing, and logging altered the structure and composition of many low-elevation forests, leading to larger and more severe burns. In higher elevation forests, changes have been less marked. Traditional low-severity prescribed fire is not likely to replicate historical conditions in these mixed or high-severity fire regimes, which include many mixed coniferous forests and all lodgepole pine (Pinus contorta) and spruce-fi r (Picea-Abies) forests. We suggest four research priorities: (1) the effects of fire severity and patch size on species’ responses to fire, (2) the possibility that postfire forests are ephemeral sources for some bird species, (3) the effect of salvage logging prescriptions on bird communities, and (4) experiments that illustrate bird responses to prescribed fire and other forest restoration methods. This research is urgent if we are to develop fire management strategies that reduce fire risk and maintain habitat for avifauna and other wildlife of the Rocky Mountains.

Variation in fire regimes of the rocky mountains: Implications for avian communities and fire management

USGS Publications Warehouse

Saab, V.A.; Powell, Hugo D.W.; Kotliar, N.B.; Newlon, K.R.

2005-01-01

Information about avian responses to fire in the U.S. Rocky Mountains is based solely on studies of crown fires. However, fire management in this region is based primarily on studies of low-elevation ponderosa pine (Pinus ponderosa) forests maintained largely by frequent understory fires. In contrast to both of these trends, most Rocky Mountain forests are subject to mixed severity fire regimes. As a result, our knowledge of bird responses to fire in the region is incomplete and skewed toward ponderosa pine forests. Research in recent large wildfires across the Rocky Mountains indicates that large burns support diverse avifauna. In the absence of controlled studies of bird responses to fire, we compared reproductive success for six cavity-nesting species using results from studies in burned and unburned habitats. Birds in ponderosa pine forests burned by stand-replacement fire tended to have higher nest success than individuals of the same species in unburned habitats, but unburned areas are needed to serve species dependent upon live woody vegetation, especially foliage gleaners. Over the last century, fire suppression, livestock grazing, and logging altered the structure and composition of many low-elevation forests, leading to larger and more severe burns. In higher elevation forests, changes have been less marked. Traditional low-severity prescribed fire is not likely to replicate historical conditions in these mixed or high-severity fire regimes, which include many mixed coniferous forests and all lodgepole pine (Pinus contorta) and spruce-fir (Picea-Abies) forests. We suggest four research priorities: (1) the effects of fire severity and patch size on species' responses to fire, (2) the possibility that postfire forests are ephemeral sources for some bird species, (3) the effect of salvage logging prescriptions on bird communities, and (4) experiments that illustrate bird responses to prescribed fire and other forest restoration methods. This research is urgent if we are to develop fire management strategies that reduce fire risk and maintain habitat for avifauna and other wildlife of the Rocky Mountains.

Non-supervised method for early forest fire detection and rapid mapping

NASA Astrophysics Data System (ADS)

Artés, Tomás; Boca, Roberto; Liberta, Giorgio; San-Miguel, Jesús

2017-09-01

Natural hazards are a challenge for the society. Scientific community efforts have been severely increased assessing tasks about prevention and damage mitigation. The most important points to minimize natural hazard damages are monitoring and prevention. This work focuses particularly on forest fires. This phenomenon depends on small-scale factors and fire behavior is strongly related to the local weather. Forest fire spread forecast is a complex task because of the scale of the phenomena, the input data uncertainty and time constraints in forest fire monitoring. Forest fire simulators have been improved, including some calibration techniques avoiding data uncertainty and taking into account complex factors as the atmosphere. Such techniques increase dramatically the computational cost in a context where the available time to provide a forecast is a hard constraint. Furthermore, an early mapping of the fire becomes crucial to assess it. In this work, a non-supervised method for forest fire early detection and mapping is proposed. As main sources, the method uses daily thermal anomalies from MODIS and VIIRS combined with land cover map to identify and monitor forest fires with very few resources. This method relies on a clustering technique (DBSCAN algorithm) and on filtering thermal anomalies to detect the forest fires. In addition, a concave hull (alpha shape algorithm) is applied to obtain rapid mapping of the fire area (very coarse accuracy mapping). Therefore, the method leads to a potential use for high-resolution forest fire rapid mapping based on satellite imagery using the extent of each early fire detection. It shows the way to an automatic rapid mapping of the fire at high resolution processing as few data as possible.

Effects of Climate and Fuels Management on Wildfire Occurrence, Size, Severity and Emissions in the Sierra Nevada

NASA Astrophysics Data System (ADS)

Westerling, A. L.; Fites, J. A.; Keyser, A.

2015-12-01

Annual wildfire burned area in federally managed Sierra Nevada forests has increased by more than 10,000 ha per decade since the early 1970s. At the same time, recent years have seen some extremely large fires compared to the historical record, with significant areas of moderate to high severity fire (e.g., McNally 2002, Rim 2013, King 2014 fires). Changes to fuels and fire regimes due to fire suppression and land use, as well as warming temperatures and the occurrence of drought, are thought to be significant factors contributing to increased risks of large, severe fires in Sierra Nevada forests. Over 70% of the vegetated area in federally managed forests in the Sierra Nevada is classified as having altered fuels and fire regimes, while average annual temperature in the Sierra Nevada has been above the long term mean for all but four years in the past two decades. As climate is expected to continue warming for decades to come, we explored fuels management scenarios as the primary tools available to modify risks of large, severe wildfires. We developed experimental statistical models of fire occurrence, fire size, and high severity burned area, to explore the interaction between climate and altered fuels conditions. These models were applied to historical climate conditions, a sample of future climate projections, and to both current fuels conditions and a range of scenarios for fuels treatments. Emissions from wildfires were estimated using the Fire Inventory from the National Center for Atmospheric Research. Our models project that average annual burned area in the Sierra Nevada will more than double by mid-century. Similarly, particulate and other pollution emissions from Sierra Nevada wildfires are projected to more than double, even if future fire severity does not change. Fuels treatment scenarios significantly reduced simulated future burned area and emissions below untreated projections. High severity burned area responded to both climate and fuels treatments. A sensitivity analysis indicated that in areas where the fraction of highly altered fuels is high, successfully restoring fuels to prehistoric conditions could more than compensate for expected climate change effects on fire severity by mid-century.

Effects of fire and post-fire salvage logging on avian communities in conifer-dominated forests of the western United States

USGS Publications Warehouse

Kotliar, N.B.; Hejl, S.J.; Hutto, R.L.; Saab, V.; Melcher, Cynthia; McFadzen, M.E.; George, T.L.; Dobkin, D.S.

2002-01-01

Historically, fire was one of the most widespread natural disturbances in the western United States. More recently, however, significant anthropogenic activities, especially fire suppression and silvicultural practices, have altered fire regimes; as a result, landscapes and associated communities have changed as well. Herein, we review current knowledge of how fire and postfire salvaging practices affect avian communities in conifer-dominated forests of the western United States. Specifically, we contrast avian communities in (1) burned vs. unburned forest, and (2) unsalvaged vs. salvage-logged burns. We also examine how variation in burn characteristics (e.g., severity, age, size) and salvage logging can alter avian communities in burns.Of the 41 avian species observed in three or more studies comparing early postfire and adjacent unburned forests, 22% are consistently more abundant in burned forests, 34% are usually more abundant in unburned forests, and 44% are equally abundant in burned and unburned forests or have varied responses. In general, woodpeckers and aerial foragers are more abundant in burned forest, whereas most foliage-gleaning species are more abundant in unburned forests. Bird species that are frequently observed in stand-replacement burns are less common in understory burns; similarly, species commonly observed in unburned forests often decrease in abundance with increasing burn severity. Granivores and species common in open-canopy forests exhibit less consistency among studies. For all species, responses to tire may be influenced by a number of factors including burn severity, fire size and shape, proximity to unburned forests, pre-and post-fire cover types, and time since fire. In addition, postfire management can alter species’ responses to burns. Most cavity-nesting species do not use severely salvaged burns, whereas some cavity-nesters persist in partially salvaged burns. Early post fire specialists, in particular, appear to prefer unsalvaged burns. We discuss several alternatives to severe salvage-logging that will help provide habitat for cavity nesters.We provide an overview of critical research questions and design considerations crucial for evaluating the effects of prescribed fire and other anthropogenic disturbances, such as forest fragmentation. Management of native avifaunas may be most successful if natural disturbance regimes, including fire, are permitted to occur when possible. Natural fires could be augmented with practices, such as prescribed fire (including high-severity fire), that mimic inherent disturbance regimes.

Short- and long-term effects on fuels, forest structure, and wildfire potential from prescribed fire and resource benefit fire in southwestern forests, USA

Treesearch

Molly E. Hunter; Jose M. Iniguez; Leigh B. Lentile

2011-01-01

Prescribed and resource benefit fires are used to manage fuels in fire-prone landscapes in the Southwest. These practices, however, typically occur under different conditions, potentially leading to differences in fire behavior and effects. The objectives of this study were to investigate the effects of recent prescribed fires, resource benefit fires, and repeated...

Synergy between land use and climate change increases future fire risk in Amazon forests

NASA Astrophysics Data System (ADS)

Le Page, Yannick; Morton, Douglas; Hartin, Corinne; Bond-Lamberty, Ben; Cardoso Pereira, José Miguel; Hurtt, George; Asrar, Ghassem

2017-12-01

Tropical forests have been a permanent feature of the Amazon basin for at least 55 million years, yet climate change and land use threaten the forest's future over the next century. Understory forest fires, which are common under the current climate in frontier forests, may accelerate Amazon forest losses from climate-driven dieback and deforestation. Far from land use frontiers, scarce fire ignitions and high moisture levels preclude significant burning, yet projected climate and land use changes may increase fire activity in these remote regions. Here, we used a fire model specifically parameterized for Amazon understory fires to examine the interactions between anthropogenic activities and climate under current and projected conditions. In a scenario of low mitigation efforts with substantial land use expansion and climate change - Representative Concentration Pathway (RCP) 8.5 - projected understory fires increase in frequency and duration, burning 4-28 times more forest in 2080-2100 than during 1990-2010. In contrast, active climate mitigation and land use contraction in RCP4.5 constrain the projected increase in fire activity to 0.9-5.4 times contemporary burned area. Importantly, if climate mitigation is not successful, land use contraction alone is very effective under low to moderate climate change, but does little to reduce fire activity under the most severe climate projections. These results underscore the potential for a fire-driven transformation of Amazon forests if recent regional policies for forest conservation are not paired with global efforts to mitigate climate change.

Estimating post-fire organic soil depth in the Alaskan boreal forest using the Normalized Burn Ratio

Treesearch

D. Verbyla; R. Lord

2008-01-01

As part of a long-term moose browse/fire severity study, we used the Normalized Burn Ratio (NBR) with historic Landsat Thematic Mapper (TM) imagery to estimate fire severity from a 1983 wildfire in interior Alaska. Fire severity was estimated in the field by measuring the depth of the organic soil at 57 sites during the summer of 2006. Sites were selected for field...

Reassessment of the use of fire as a management tool in deciduous forests of eastern North America.

PubMed

Matlack, Glenn R

2013-10-01

Prescribed burning is increasingly being used in the deciduous forests of eastern North America. Recent work suggests that historical fire frequency has been overestimated east of the prairie-woodland transition zone, and its introduction could potentially reduce forest herb and shrub diversity. Fire-history recreations derived from sedimentary charcoal, tree fire scars, and estimates of Native American burning suggest point-return times ranging from 5-10 years to centuries and millennia. Actual return times were probably longer because such records suffer from selective sampling, small sample sizes, and a probable publication bias toward frequent fire. Archeological evidence shows the environmental effect of fire could be severe in the immediate neighborhood of a Native American village. Population density appears to have been low through most of the Holocene, however, and villages were strongly clustered at a regional scale. Thus, it appears that the majority of forests of the eastern United States were little affected by burning before European settlement. Use of prescribed burning assumes that most forest species are tolerant of fire and that burning will have only a minimal effect on diversity. However, common adaptations such as serotiny, epicormic sprouting, resprouting from rhizomes, and smoke-cued germination are unknown across most of the deciduous region. Experimental studies of burning show vegetation responses similar to other forms of disturbance that remove stems and litter and do not necessarily imply adaptation to fire. The general lack of adaptation could potentially cause a reduction in diversity if burning were introduced. These observations suggest a need for a fine-grained examination of fire history with systematic sampling in which all subregions, landscape positions, and community types are represented. Responses to burning need to be examined in noncommercial and nonwoody species in rigorous manipulative experiments. Until such information is available, it seems prudent to limit the use of prescribed burning east of the prairie-woodland transition zone. © 2013 Society for Conservation Biology.

Temporal trends in mammal responses to fire reveals the complex effects of fire regime attributes.

PubMed

Lindenmayer, David B; Blanchard, Wade; MacGregor, Christopher; Barton, Philip; Banks, Sam C; Crane, Mason; Michael, Damian; Okada, Sachiko; Berry, Laurence; Florance, Daniel; Gill, Malcolm

2016-03-01

Fire is a major ecological process in many ecosystems worldwide. We sought to identify which attributes of fire regimes affect temporal change in the presence and abundance of Australian native mammals. Our detailed study was underpinned by time series data on 11 mammal species at 97 long-term sites in southeastern Australia between 2003 and 2013. We explored how temporal aspects of fire regimes influenced the presence and conditional abundance of species. The key fire regime components examined were: (1) severity of a major fire in 2003, (2) interval between the last major fire (2003) and the fire prior to that, and (3) number of past fires. Our long-term data set enabled quantification of the interactions between survey year and each fire regime variable: an ecological relationship missing from temporally restricted studies. We found no evidence of any appreciable departures from the assumption of independence of the sites. Multiple aspects of fire regimes influenced temporal variation in the presence and abundance of mammals. The best models indicated that six of the 11 species responded to two or more fire regime variables, with two species influenced by all three fire regime attributes. Almost all species responded to time since fire, either as an interaction with survey year or as a main effect. Fire severity or its interaction with survey year was important for most terrestrial rodents. The number of fires at a site was significant for terrestrial rodents and several other species. Our findings contain evidence of the effects on native mammals of heterogeneity in fire regimes. Temporal response patterns of mammal species were influenced by multiple fire regime attributes, often in conjunction with survey year. This underscores the critical importance of long-term studies of biota that are coupled with data sets characterized by carefully documented fire history, severity, and frequency. Long-term studies are essential to predict animal responses to fires and guide management of when and where (prescribed) fire or, conversely, long-unburned vegetation is needed. The complexity of observed responses highlights the need for large reserves in which patterns of heterogeneity in fire regimes can be sustained in space and over time.

Simulation of quaking aspen potential fire behavior in Northern Utah, USA

Treesearch

R. Justin DeRose; A. Joshua Leffler

2014-01-01

Current understanding of aspen fire ecology in western North America includes the paradoxical characterization that aspen-dominated stands, although often regenerated following fire, are “fire-proof”. We tested this idea by predicting potential fire behavior across a gradient of aspen dominance in northern Utah using the Forest Vegetation Simulator and the Fire and...

Rill and gully formation following the 2010 Schultz Fire

Treesearch

Daniel G. Neary; Karen A. Koestner; Ann Youberg; Peter E. Koestner

2011-01-01

The Schultz Fire burned 6,100 ha on the eastern slopes of the San Francisco Peaks across moderate to very steep ponderosa pine and mixed conifer watersheds. There was widespread occurrence of high severity fire, with several watersheds classified as over 50% high severity. This resulted in moderate to severe water repellency in most soils, especially those on steep...

Average Stand Age from Forest Inventory Plots Does Not Describe Historical Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America

PubMed Central

Stevens, Jens T.; Safford, Hugh D.; North, Malcolm P.; Fried, Jeremy S.; Gray, Andrew N.; Brown, Peter M.; Dolanc, Christopher R.; Dobrowski, Solomon Z.; Falk, Donald A.; Farris, Calvin A.; Franklin, Jerry F.; Fulé, Peter Z.; Hagmann, R. Keala; Knapp, Eric E.; Miller, Jay D.; Smith, Douglas F.; Swetnam, Thomas W.; Taylor, Alan H.

2016-01-01

Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the “stand age” variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age basal area in 58% of plots analyzed and more than 30% of pre-stand age basal area in 32% of plots, and 2) recruitment events are not necessarily related to high-severity fire occurrence. Because the FIA stand age variable is estimated from a sample of tree ages within the tree size class containing a plurality of canopy trees in the plot, it does not necessarily include the oldest trees, especially in uneven-aged stands. Thus, the FIA stand age variable does not indicate whether the trees in the predominant size class established in response to severe fire, or established during the absence of fire. FIA stand age was not designed to measure the time since a stand-replacing disturbance. Quantification of historical “mixed-severity” fire regimes must be explicit about the spatial scale of high-severity fire effects, which is not possible using FIA stand age data. PMID:27196621

An algorithm to detect fire activity using Meteosat: fine tuning and quality assesment

NASA Astrophysics Data System (ADS)

Amraoui, M.; DaCamara, C. C.; Ermida, S. L.

2012-04-01

Hot spot detection by means of sensors on-board geostationary satellites allows studying wildfire activity at hourly and even sub-hourly intervals, an advantage that cannot be met by polar orbiters. Since 1997, the Satellite Application Facility for Land Surface Analysis has been running an operational procedure that allows detecting active fires based on information from Meteosat-8/SEVIRI. This is the so-called Fire Detection and Monitoring (FD&M) product and the procedure takes advantage of the temporal resolution of SEVIRI (one image every 15 min), and relies on information from SEVIRI channels (namely 0.6, 0.8, 3.9, 10.8 and 12.0 μm) together with information on illumination angles. The method is based on heritage from contextual algorithms designed for polar, sun-synchronous instruments, namely NOAA/AVHRR and MODIS/TERRAAQUA. A potential fire pixel is compared with the neighboring ones and the decision is made based on relative thresholds as derived from the pixels in the neighborhood. Generally speaking, the observed fire incidence compares well against hot spots extracted from the global daily active fire product developed by the MODIS Fire Team. However, values of probability of detection (POD) tend to be quite low, a result that may be partially expected by the finer resolution of MODIS. The aim of the present study is to make a systematic assessment of the impacts on POD and False Alarm Ratio (FAR) of the several parameters that are set in the algorithms. Such parameters range from the threshold values of brightness temperature in the IR3.9 and 10.8 channels that are used to select potential fire pixels up to the extent of the background grid and thresholds used to statistically characterize the radiometric departures of a potential pixel from the respective background. The impact of different criteria to identify pixels contaminated by clouds, smoke and sun glint is also evaluated. Finally, the advantages that may be brought to the algorithm by adding contextual tests in the time domain are discussed. The study lays the grounds to the development of improved quality flags that will be integrated in the FD&M product in the nearby future.

Hazard Science in Support of Community Resiliency: The Response of the Multi Hazards Demonstration Project to the 2009 Station Fire in Los Angeles County

NASA Astrophysics Data System (ADS)

Jones, L. M.; Bawden, G. W.; Bowers, J.; Cannon, S.; Cox, D. A.; Fisher, R.; Keeley, J.; Perry, S. C.; Plumlee, G. S.; Wood, N. J.

2009-12-01

The “Station” fire, the largest fire in the history of Los Angeles County in southern California, began on August 26, 2009 and as of the abstract deadline had burned over 150,000 acres of the Angeles National Forest. This fire creates both a demand and an opportunity for hazards science to be used by the communities directly hit by the fire, as well as those downstream of possible postfire impacts. The Multi Hazards Demonstration Project of the USGS is deploying several types of scientific response, including 1) evaluation of potential debris-flow hazards and associated risk, 2) monitoring physical conditions in burned areas and the hydrologic response to rainstorms, 3) increased streamflow monitoring, 4) ash analysis and ground water contamination, 5) ecosystem response and endangered species rescue, 6) lidar data acquisition for evaluations of biomass loss, detailed mapping of the physical processes that lead to debris-flow generation, and other geologic investigations. The Multi Hazards Demonstration Project is working with the southern California community to use the resulting information to better manage the social consequences of the fire and its secondary hazards. In particular, we are working with Los Angeles County to determine what information they need to prioritize recovery efforts. For instance, maps of hazards specific to debris flow potential can help identify the highest priority areas for debris flow mitigation efforts. These same maps together with ecosystem studies will help land managers determine whether individuals from endangered species should be removed to zoos or other refuges during the rainy months. The ash analysis will help water managers prevent contamination to water supplies. Plans are just beginning for a public information campaign with Los Angeles County about the risk posed by potential debris flows that should be underway in December. Activities from the fire response will support the development of the Wildfire Scenario in 2011, which will examine implications of land-use decisions in the frequency of fires in southern California.

Assessment of Greenhouse Gas Retrofit Issues for Coal Fired Power Plants

EPA Science Inventory

Several studies have been published on carbon capture technology as an independent island. In contrast, this evaluation considered the impact on the existing plant and the potential improvements to ease the retrofit of a carbon capture process. This paper will provide insight i...

The influence of wildfire extent and severity on streamwater chemistry, sediment and temperature following the Hayman Fire, Colorado

Treesearch

Charles C. Rhoades; Deborah Entwistle; Dana Butler

2011-01-01

The 2002 Hayman Fire was the largest fire in recent Colorado history (558 km2). The extent of high severity combustion and possible effects on Denver's water supply focussed public attention on the effects of wildfire on water quality.Wemonitored stream chemistry, temperature and sediment before the fire and at monthly intervals for 5 years after the fire. The...

Patch structure, fire-scar formation, and tree regeneration in a large mixed-severity fire in the South Dakota Black Hills, USA

Treesearch

Leigh B. Lentile; Frederick W. Smith; Wayne D. Shepperd

2005-01-01

We compared patch structure, fire-scar formation, and seedling regeneration in patches of low, moderate, and high burn severity following the large (~34 000 ha) Jasper fire of 2000 that occurred in ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) forests of the Black Hills of South Dakota, USA. This fire created a patchy mosaic of effects...

Evaluation of the composite burn index for assessing fire severity in Alaskan black spruce forests

Treesearch

Eric S. Kasischke; Merritt R. Turetsky; Roger D. Ottmar; Nancy H.F. French; Elizabeth E. Hoy; Evan S. Kane

2008-01-01

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, percentage of trees standing after the fire, depth of the organic layer remaining after the fire, depth of burning...

Fire severity mediates climate-driven shifts in understorey community composition of black spruce stands of interior Alaska

Treesearch

Emily L. Bernhardt; Teresa N. Hollingsworth; F. Stuart Chapin

2011-01-01

Question: How do pre-fire conditions (community composition and environmental characteristics) and climate-driven disturbance characteristics (fire severity) affect post-fire community composition in black spruce stands? Location: Northern boreal forest, interior Alaska. Methods: We compared plant community composition and environmental stand characteristics in 14...

Using unplanned fires to help suppressing future large fires in Mediterranean forests.

PubMed

Regos, Adrián; Aquilué, Núria; Retana, Javier; De Cáceres, Miquel; Brotons, Lluís

2014-01-01

Despite the huge resources invested in fire suppression, the impact of wildfires has considerably increased across the Mediterranean region since the second half of the 20th century. Modulating fire suppression efforts in mild weather conditions is an appealing but hotly-debated strategy to use unplanned fires and associated fuel reduction to create opportunities for suppression of large fires in future adverse weather conditions. Using a spatially-explicit fire-succession model developed for Catalonia (Spain), we assessed this opportunistic policy by using two fire suppression strategies that reproduce how firefighters in extreme weather conditions exploit previous fire scars as firefighting opportunities. We designed scenarios by combining different levels of fire suppression efficiency and climatic severity for a 50-year period (2000-2050). An opportunistic fire suppression policy induced large-scale changes in fire regimes and decreased the area burnt under extreme climate conditions, but only accounted for up to 18-22% of the area to be burnt in reference scenarios. The area suppressed in adverse years tended to increase in scenarios with increasing amounts of area burnt during years dominated by mild weather. Climate change had counterintuitive effects on opportunistic fire suppression strategies. Climate warming increased the incidence of large fires under uncontrolled conditions but also indirectly increased opportunities for enhanced fire suppression. Therefore, to shift fire suppression opportunities from adverse to mild years, we would require a disproportionately large amount of area burnt in mild years. We conclude that the strategic planning of fire suppression resources has the potential to become an important cost-effective fuel-reduction strategy at large spatial scale. We do however suggest that this strategy should probably be accompanied by other fuel-reduction treatments applied at broad scales if large-scale changes in fire regimes are to be achieved, especially in the wider context of climate change.

The Influence of Wildfire on Long-Term Erosion: Insights from the Jemez Mountains, NM and the Western USA

NASA Astrophysics Data System (ADS)

Fitch, E. P.; Meyer, G. A.

2017-12-01

A major influence of wildfire on long-term erosion in the western USA is strongly suggested by extreme postfire debris flows and floods, where fire severity has increased in recent decades due to climate change and land use. Roughly 30% of the ponderosa-mixed conifer forests of the Jemez Mountains has burned in the last 20 yr, much at high severity, whereas tree-ring data indicate mostly lower-severity burns from 1600-1900 CE, before fire suppression and grazing. Fire-related alluvial deposits proximal to hillslopes reflect mostly small to moderate erosional events over the last 4000 yr, compared to thick, bouldery debris-flow deposits from recent severe fires; some modern postfire debris flows appear truly extreme in comparison to Holocene deposits. Recognizable fire-related deposits make up 77% of fans from moist north aspects, as relatively dense vegetation and thick soil yield minor surface runoff unless severely burned. Only 39% of fan sediments from drier south aspects are fire-related, however, as sparser vegetation and exposed bedrock can produce runoff and sediment when unburned. Peaks in fire-related sedimentation at 1800, 650, 410, and 300 cal yr BP coincide with severe droughts, often preceded by wetter decades that could suppress fire activity and promote denser stands. Although the Medieval Climatic Anomaly (MCA, 1050-700 cal yr BP) was marked by generally warmer temperatures and multidecadal episodes of widespread, severe drought in the western USA, fire-related sedimentation was relatively minor in the Jemez Mountains. In contrast, dense subalpine forests of Yellowstone and central Idaho burned less frequently and more severely in the late Holocene, and produced major debris flows in the MCA. Fire accounts for only 30-50% of Holocene fan deposition in these areas, as steep unburned basins also produce large debris flows in extreme storms. The relative importance of fire in erosion depends on topography, bedrock, soil cover, and forest composition and density; potent climatic influence on the latter makes it difficult to generalize about how strongly fire drives long-term erosion rates, as even local aspect is important. Also, our data represent interglacial environments that are uncommon over the Quaternary, such that extrapolation of fire's importance beyond the last 104 yr is unwarranted.

Estimating wildfire risk on a Mojave Desert landscape using remote sensing and field sampling

USGS Publications Warehouse

Van Linn, Peter F.; Nussear, Kenneth E.; Esque, Todd C.; DeFalco, Lesley A.; Inman, Richard D.; Abella, Scott R.

2013-01-01

Predicting wildfires that affect broad landscapes is important for allocating suppression resources and guiding land management. Wildfire prediction in the south-western United States is of specific concern because of the increasing prevalence and severe effects of fire on desert shrublands and the current lack of accurate fire prediction tools. We developed a fire risk model to predict fire occurrence in a north-eastern Mojave Desert landscape. First we developed a spatial model using remote sensing data to predict fuel loads based on field estimates of fuels. We then modelled fire risk (interactions of fuel characteristics and environmental conditions conducive to wildfire) using satellite imagery, our model of fuel loads, and spatial data on ignition potential (lightning strikes and distance to roads), topography (elevation and aspect) and climate (maximum and minimum temperatures). The risk model was developed during a fire year at our study landscape and validated at a nearby landscape; model performance was accurate and similar at both sites. This study demonstrates that remote sensing techniques used in combination with field surveys can accurately predict wildfire risk in the Mojave Desert and may be applicable to other arid and semiarid lands where wildfires are prevalent.

Mechanisms and consequences of action potential burst firing in rat neocortical pyramidal neurons

PubMed Central

Williams, Stephen R; Stuart, Greg J

1999-01-01

Electrophysiological recordings and pharmacological manipulations were used to investigate the mechanisms underlying the generation of action potential burst firing and its postsynaptic consequences in visually identified rat layer 5 pyramidal neurons in vitro.Based upon repetitive firing properties and subthreshold membrane characteristics, layer 5 pyramidal neurons were separated into three classes: regular firing and weak and strong intrinsically burst firing.High frequency (330 ± 10 Hz) action potential burst firing was abolished or greatly weakened by the removal of Ca2+ (n = 5) from, or by the addition of the Ca2+ channel antagonist Ni2+ (250–500 μm; n = 8) to, the perfusion medium.The blockade of apical dendritic sodium channels by the local dendritic application of TTX (100 nm; n = 5) abolished or greatly weakened action potential burst firing, as did the local apical dendritic application of Ni2+ (1 mm; n = 5).Apical dendritic depolarisation resulted in low frequency (157 ± 26 Hz; n = 6) action potential burst firing in regular firing neurons, as classified by somatic current injection. The intensity of action potential burst discharges in intrinsically burst firing neurons was facilitated by dendritic depolarisation (n = 11).Action potential amplitude decreased throughout a burst when recorded somatically, suggesting that later action potentials may fail to propagate axonally. Axonal recordings demonstrated that each action potential in a burst is axonally initiated and that no decrement in action potential amplitude is apparent in the axon > 30 μm from the soma.Paired recordings (n = 16) from synaptically coupled neurons indicated that each action potential in a burst could cause transmitter release. EPSPs or EPSCs evoked by a presynaptic burst of action potentials showed use-dependent synaptic depression.A postsynaptic, TTX-sensitive voltage-dependent amplification process ensured that later EPSPs in a burst were amplified when generated from membrane potentials positive to -60 mV, providing a postsynaptic mechanism that counteracts use-dependent depression at synapses between layer 5 pyramidal neurons. PMID:10581316

The potential and realized spread of wildfires across Canada.

PubMed

Wang, Xianli; Parisien, Marc-André; Flannigan, Mike D; Parks, Sean A; Anderson, Kerry R; Little, John M; Taylor, Steve W

2014-08-01

Given that they can burn for weeks or months, wildfires in temperate and boreal forests may become immense (eg., 10(0) - 10(4) km(2) ). However, during the period within which a large fire is 'active', not all days experience weather that is conducive to fire spread; indeed most of the spread occurs on a small proportion (e.g., 1 - 15 days) of not necessarily consecutive days during the active period. This study examines and compares the Canada-wide patterns in fire-conducive weather ('potential' spread) and the spread that occurs on the ground ('realized' spread). Results show substantial variability in distributions of potential and realized spread days across Canada. Both potential and realized spread are higher in western than in eastern Canada; however, whereas potential spread generally decreases from south to north, there is no such pattern with realized spread. The realized-to-potential fire-spread ratio is considerably higher in northern Canada than in the south, indicating that proportionally more fire-conducive days translate into fire progression. An exploration of environmental correlates to spread show that there may be a few factors compensating for the lower potential spread in northern Canada: a greater proportion of coniferous (i.e., more flammable) vegetation, lesser human impacts (i.e., less fragmented landscapes), sufficient fire ignitions, and intense droughts. Because a linear relationship exists between the frequency distributions of potential spread days and realized spread days in a fire zone, it is possible to obtain one from the other using a simple conversion factor. Our methodology thus provides a means to estimate realized fire spread from weather-based data in regions where fire databases are poor, which may improve our ability to predict future fire activity. © 2014 John Wiley & Sons Ltd.

Near-Real-Time Earth Observation Data Supporting Wildfire Management

NASA Astrophysics Data System (ADS)

Ambrosia, V. G.; Zajkowski, T.; Quayle, B.

2013-12-01

During disaster events, the most critical element needed by responding personnel and management teams is situational intelligence / awareness. During rapidly-evolving events such as wildfires, the need for timely information is critical to save lives, property and resources. The wildfire management agencies in the US rely heavily on remote sensing information both from airborne platforms as well as from orbital assets. The ability to readily have information from those systems, not just data, is critical to effective control and damage mitigation. NASA has been collaborating with the USFS to mature and operationalize various asset-information capabilities to effect improved knowledge of fire-prone areas, monitor wildfire events in real-time, assess effectiveness of fire management strategies, and provide rapid, post-fire assessment for recovery operations. Specific examples of near-real-time remote sensing asset utility include daily MODIS data employed to assess fire potential / wildfire hazard areas, and national-scale hot-spot detection, airborne thermal sensor collected during wildfire events to effect management strategies, EO-1 ALI 'pointable' satellite sensor data to assess fire-retardant application effectiveness, and Landsat 8 and other sensor data to derive burn severity indices for post-fire remediation work. These cases of where near-real-time data is used operationally during the previous few fire seasons will be presented.

Restoring and managing low-severity fire in dry-forest landscapes of the western USA.

PubMed

Baker, William L

2017-01-01

Low-severity fires that killed few canopy trees played a significant historical role in dry forests of the western USA and warrant restoration and management, but historical rates of burning remain uncertain. Past reconstructions focused on on dating fire years, not measuring historical rates of burning. Past statistics, including mean composite fire interval (mean CFI) and individual-tree fire interval (mean ITFI) have biases and inaccuracies if used as estimators of rates. In this study, I used regression, with a calibration dataset of 96 cases, to test whether these statistics could accurately predict two equivalent historical rates, population mean fire interval (PMFI) and fire rotation (FR). The best model, using Weibull mean ITFI, had low prediction error and R2adj = 0.972. I used this model to predict historical PMFI/FR at 252 sites spanning dry forests. Historical PMFI/FR for a pool of 342 calibration and predicted sites had a mean of 39 years and median of 30 years. Short (< 25 years) mean PMFI/FRs were in Arizona and New Mexico and scattered in other states. Long (> 55 years) mean PMFI/FRs were mainly from northern New Mexico to South Dakota. Mountain sites often had a large range in PMFI/FR. Nearly all 342 estimates are for old forests with a history of primarily low-severity fire, found across only about 34% of historical dry-forest area. Frequent fire (PMFI/FR < 25 years) was found across only about 14% of historical dry-forest area, with 86% having multidecadal rates of low-severity fire. Historical fuels (e.g., understory shrubs and small trees) could fully recover between multidecadal fires, allowing some denser forests and some ecosystem processes and wildlife habitat to be less limited by fire. Lower historical rates mean less restoration treatment is needed before beginning managed fire for resource benefits, where feasible. Mimicking patterns of variability in historical low-severity fire regimes would likely benefit biological diversity and ecosystem functioning.

Restoring and managing low-severity fire in dry-forest landscapes of the western USA

PubMed Central

2017-01-01

Low-severity fires that killed few canopy trees played a significant historical role in dry forests of the western USA and warrant restoration and management, but historical rates of burning remain uncertain. Past reconstructions focused on on dating fire years, not measuring historical rates of burning. Past statistics, including mean composite fire interval (mean CFI) and individual-tree fire interval (mean ITFI) have biases and inaccuracies if used as estimators of rates. In this study, I used regression, with a calibration dataset of 96 cases, to test whether these statistics could accurately predict two equivalent historical rates, population mean fire interval (PMFI) and fire rotation (FR). The best model, using Weibull mean ITFI, had low prediction error and R2adj = 0.972. I used this model to predict historical PMFI/FR at 252 sites spanning dry forests. Historical PMFI/FR for a pool of 342 calibration and predicted sites had a mean of 39 years and median of 30 years. Short (< 25 years) mean PMFI/FRs were in Arizona and New Mexico and scattered in other states. Long (> 55 years) mean PMFI/FRs were mainly from northern New Mexico to South Dakota. Mountain sites often had a large range in PMFI/FR. Nearly all 342 estimates are for old forests with a history of primarily low-severity fire, found across only about 34% of historical dry-forest area. Frequent fire (PMFI/FR < 25 years) was found across only about 14% of historical dry-forest area, with 86% having multidecadal rates of low-severity fire. Historical fuels (e.g., understory shrubs and small trees) could fully recover between multidecadal fires, allowing some denser forests and some ecosystem processes and wildlife habitat to be less limited by fire. Lower historical rates mean less restoration treatment is needed before beginning managed fire for resource benefits, where feasible. Mimicking patterns of variability in historical low-severity fire regimes would likely benefit biological diversity and ecosystem functioning. PMID:28199416

The role of fire-return interval and season of burn in snag dynamics in a south Florida slash pine forest

USGS Publications Warehouse

Lloyd, John D.; Slater, Gary L.; Snyder, James R.

2012-01-01

Standing dead trees, or snags, are an important habitat element for many animal species. In many ecosystems, fire is a primary driver of snag population dynamics because it can both create and consume snags. The objective of this study was to examine how variation in two key components of the fire regime—fire-return interval and season of burn—affected population dynamics of snags. Using a factorial design, we exposed 1 ha plots, located within larger burn units in a south Florida slash pine (Pinus elliottii var. densa Little and Dorman) forest, to prescribed fire applied at two intervals (approximately 3-year intervals vs. approximately 6-year intervals) and during two seasons (wet season vs. dry season) over a 12- to 13-year period. We found no consistent effect of fire season or frequency on the density of lightly to moderately decayed or heavily decayed snags, suggesting that variation in these elements of the fire regime at the scale we considered is relatively unimportant in the dynamics of snag populations. However, our confidence in these findings is limited by small sample sizes, potentially confounding effects of unmeasured variation in fire behavior and effects (e.g., intensity, severity, synergy with drought cycles) and wide variation in responses within a treatment level. The generalizing of our findings is also limited by the narrow range of treatment levels considered. Future experiments incorporating a wider range of fire regimes and directly quantifying fire intensity would prove useful in identifying more clearly the role of fire in shaping the dynamics of snag populations.

Predicting fire effects on water quality: a perspective and future needs

NASA Astrophysics Data System (ADS)

Smith, Hugh; Sheridan, Gary; Nyman, Petter; Langhans, Christoph; Noske, Philip; Lane, Patrick

2017-04-01

Forest environments are a globally significant source of drinking water. Fire presents a credible threat to the supply of high quality water in many forested regions. The post-fire risk to water supplies depends on storm event characteristics, vegetation cover and fire-related changes in soil infiltration and erodibility modulated by landscape position. The resulting magnitude of runoff generation, erosion and constituent flux to streams and reservoirs determines the severity of water quality impacts in combination with the physical and chemical composition of the entrained material. Research to date suggests that most post-fire water quality impacts are due to large increases in the supply of particulates (fine-grained sediment and ash) and particle-associated chemical constituents. The largest water quality impacts result from high magnitude erosion events, including debris flow processes, which typically occur in response to short duration, high intensity storm events during the recovery period. Most research to date focuses on impacts on water quality after fire. However, information on potential water quality impacts is required prior to fire events for risk planning. Moreover, changes in climate and forest management (e.g. prescribed burning) that affect fire regimes may alter water quality risks. Therefore, prediction requires spatial-temporal representation of fire and rainfall regimes coupled with information on fire-related changes to soil hydrologic parameters. Recent work has applied such an approach by combining a fire spread model with historic fire weather data in a Monte Carlo simulation to quantify probabilities associated with fire and storm events generating debris flows and fine sediment influx to a reservoir located in Victoria, Australia. Prediction of fire effects on water quality would benefit from further research in several areas. First, more work on regional-scale stochastic modelling of intersecting fire and storm events with landscape zones of erosion vulnerability is required to support quantitative evaluation of water quality risk and the effect of future changes in climate and land management. Second, we underscore previous calls for characterisation of landscape-scale domains to support regionalisation of parameter sets derived from empirical studies. Recent examples include work identifying aridity as a control of hydro-geomorphic response to fire and the use of spectral-based indices to predict spatial heterogeneity in ash loadings. Third, information on post-fire erosion from colluvial or alluvial stores is needed to determine their significance as both sediment-contaminant sinks and sources. Such sediment stores may require explicit spatial representation in risk models for some environments and sediment tracing can be used to determine their relative importance as secondary sources. Fourth, increased dating of sediment archives could provide regional datasets of fire-related erosion event frequency. Presently, the lack of such data hinders evaluation of risk models linking fire and storm events to erosion and water quality impacts.

Fire severity classification: Uses and abuses

Treesearch

Theresa B. Jain; Russell T. Graham

2003-01-01

Burn severity (also referred to as fire severity) is not a single definition, but rather a concept and its classification is a function of the measured units unique to the system of interest. The systems include: flora and fauna, soil microbiology and hydrologic processes, atmospheric inputs, fire management, and society. Depending on the particular system of interest...

Quercus kelloggii (Newb.) sprout response to fire severity in northern California

Treesearch

Justin S. Crotteau; Martin W. Ritchie; J. Morgan Varner; John-Pascal Berrill

2015-01-01

We counted seedlings and assessed crown characteristics and abundance of fire-induced stump sprout regeneration in California black oak (Quercus kelloggii) 11 to 12 years after wildfire. Regeneration was examined across three levels of burn severity (low, moderate, and high) according to the Composite Burn Index. Fire severity affected crown width...

Fire Effects at the Tundra-Boreal Ecotone in Interior Alaska

NASA Astrophysics Data System (ADS)

Howard, B. K.; Mack, M. C.; Johnstone, J. F.; Walker, X. J.; Roland, C.

2016-12-01

Climate warming in northern latitudes has led to an intensification of disturbance by wildfire. Little is known about the effects of fire on tundra vegetation. Changes in vegetation composition could have important implications for carbon cycling , and may feedback positively or negatively to future climate change (Randerson et al., 2006). Our study utilizes extensive pre-fire ecological data collected by the National Park Service (NPS) Inventory and Monitoring (I&M) program to assess the prefire conditions important in driving successional pathways within Denali National Park and Preserve. In 2013, the East Toklat fire burned 30,000 acres of tussock tundra and mixed white and black spruce forest at a high severity, which encompassed 50 NPS plots that were originally monitored in 2003. Our sampling occurred the summer of 2016 following the same NPS protocols to assess post-fire vegetation composition. In addition, we conducted a seeding experiment using locally collected white and black spruce seed to assess natural and potential tree regeneration in unburned and post fire environments. Seed traps were established along our transects to assess seed rain. A multivariate approach will be used to assess post-fire community dynamics and future field seasons will address tree germination and survival rates. These data will then be coupled with pre and post-fire ecological data to parse out important factors driving secondary succession.

The human dimension of fire regimes on Earth.

PubMed

Bowman, David M J S; Balch, Jennifer; Artaxo, Paulo; Bond, William J; Cochrane, Mark A; D'Antonio, Carla M; Defries, Ruth; Johnston, Fay H; Keeley, Jon E; Krawchuk, Meg A; Kull, Christian A; Mack, Michelle; Moritz, Max A; Pyne, Stephen; Roos, Christopher I; Scott, Andrew C; Sodhi, Navjot S; Swetnam, Thomas W; Whittaker, Robert

2011-12-01

Humans and their ancestors are unique in being a fire-making species, but 'natural' (i.e. independent of humans) fires have an ancient, geological history on Earth. Natural fires have influenced biological evolution and global biogeochemical cycles, making fire integral to the functioning of some biomes. Globally, debate rages about the impact on ecosystems of prehistoric human-set fires, with views ranging from catastrophic to negligible. Understanding of the diversity of human fire regimes on Earth in the past, present and future remains rudimentary. It remains uncertain how humans have caused a departure from 'natural' background levels that vary with climate change. Available evidence shows that modern humans can increase or decrease background levels of natural fire activity by clearing forests, promoting grazing, dispersing plants, altering ignition patterns and actively suppressing fires, thereby causing substantial ecosystem changes and loss of biodiversity. Some of these contemporary fire regimes cause substantial economic disruptions owing to the destruction of infrastructure, degradation of ecosystem services, loss of life, and smoke-related health effects. These episodic disasters help frame negative public attitudes towards landscape fires, despite the need for burning to sustain some ecosystems. Greenhouse gas-induced warming and changes in the hydrological cycle may increase the occurrence of large, severe fires, with potentially significant feedbacks to the Earth system. Improved understanding of human fire regimes demands: (1) better data on past and current human influences on fire regimes to enable global comparative analyses, (2) a greater understanding of different cultural traditions of landscape burning and their positive and negative social, economic and ecological effects, and (3) more realistic representations of anthropogenic fire in global vegetation and climate change models. We provide an historical framework to promote understanding of the development and diversification of fire regimes, covering the pre-human period, human domestication of fire, and the subsequent transition from subsistence agriculture to industrial economies. All of these phases still occur on Earth, providing opportunities for comparative research.

The human dimension of fire regimes on Earth

PubMed Central

Bowman, David M J S; Balch, Jennifer; Artaxo, Paulo; Bond, William J; Cochrane, Mark A; D'Antonio, Carla M; DeFries, Ruth; Johnston, Fay H; Keeley, Jon E; Krawchuk, Meg A; Kull, Christian A; Mack, Michelle; Moritz, Max A; Pyne, Stephen; Roos, Christopher I; Scott, Andrew C; Sodhi, Navjot S; Swetnam, Thomas W; Whittaker, Robert

2011-01-01

Humans and their ancestors are unique in being a fire-making species, but ‘natural’ (i.e. independent of humans) fires have an ancient, geological history on Earth. Natural fires have influenced biological evolution and global biogeochemical cycles, making fire integral to the functioning of some biomes. Globally, debate rages about the impact on ecosystems of prehistoric human-set fires, with views ranging from catastrophic to negligible. Understanding of the diversity of human fire regimes on Earth in the past, present and future remains rudimentary. It remains uncertain how humans have caused a departure from ‘natural’ background levels that vary with climate change. Available evidence shows that modern humans can increase or decrease background levels of natural fire activity by clearing forests, promoting grazing, dispersing plants, altering ignition patterns and actively suppressing fires, thereby causing substantial ecosystem changes and loss of biodiversity. Some of these contemporary fire regimes cause substantial economic disruptions owing to the destruction of infrastructure, degradation of ecosystem services, loss of life, and smoke-related health effects. These episodic disasters help frame negative public attitudes towards landscape fires, despite the need for burning to sustain some ecosystems. Greenhouse gas-induced warming and changes in the hydrological cycle may increase the occurrence of large, severe fires, with potentially significant feedbacks to the Earth system. Improved understanding of human fire regimes demands: (1) better data on past and current human influences on fire regimes to enable global comparative analyses, (2) a greater understanding of different cultural traditions of landscape burning and their positive and negative social, economic and ecological effects, and (3) more realistic representations of anthropogenic fire in global vegetation and climate change models. We provide an historical framework to promote understanding of the development and diversification of fire regimes, covering the pre-human period, human domestication of fire, and the subsequent transition from subsistence agriculture to industrial economies. All of these phases still occur on Earth, providing opportunities for comparative research. PMID:22279247

Using Unplanned Fires to Help Suppressing Future Large Fires in Mediterranean Forests

PubMed Central

Regos, Adrián; Aquilué, Núria; Retana, Javier; De Cáceres, Miquel; Brotons, Lluís

2014-01-01

Despite the huge resources invested in fire suppression, the impact of wildfires has considerably increased across the Mediterranean region since the second half of the 20th century. Modulating fire suppression efforts in mild weather conditions is an appealing but hotly-debated strategy to use unplanned fires and associated fuel reduction to create opportunities for suppression of large fires in future adverse weather conditions. Using a spatially-explicit fire–succession model developed for Catalonia (Spain), we assessed this opportunistic policy by using two fire suppression strategies that reproduce how firefighters in extreme weather conditions exploit previous fire scars as firefighting opportunities. We designed scenarios by combining different levels of fire suppression efficiency and climatic severity for a 50-year period (2000–2050). An opportunistic fire suppression policy induced large-scale changes in fire regimes and decreased the area burnt under extreme climate conditions, but only accounted for up to 18–22% of the area to be burnt in reference scenarios. The area suppressed in adverse years tended to increase in scenarios with increasing amounts of area burnt during years dominated by mild weather. Climate change had counterintuitive effects on opportunistic fire suppression strategies. Climate warming increased the incidence of large fires under uncontrolled conditions but also indirectly increased opportunities for enhanced fire suppression. Therefore, to shift fire suppression opportunities from adverse to mild years, we would require a disproportionately large amount of area burnt in mild years. We conclude that the strategic planning of fire suppression resources has the potential to become an important cost-effective fuel-reduction strategy at large spatial scale. We do however suggest that this strategy should probably be accompanied by other fuel-reduction treatments applied at broad scales if large-scale changes in fire regimes are to be achieved, especially in the wider context of climate change. PMID:24727853

The human dimension of fire regimes on Earth

USGS Publications Warehouse

Bowman, David M.J.S.; Balch, Jennifer; Artaxo, Paulo; Bond, William J.; Cochrane, Mark A.; D'Antonio, Carla M.; DeFries, Ruth; Johnston, Fay H.; Keeley, Jon E.; Krawchuk, Meg A.; Kull, Christian A.; Michelle, Mack; Moritz, Max A.; Pyne, Stephen; Roos, Christopher I.; Scott, Andrew C.; Sodhi, Navjot S.; Swetnam, Thomas W.

2011-01-01

Humans and their ancestors are unique in being a fire-making species, but 'natural' (i.e. independent of humans) fires have an ancient, geological history on Earth. Natural fires have influenced biological evolution and global biogeochemical cycles, making fire integral to the functioning of some biomes. Globally, debate rages about the impact on ecosystems of prehistoric human-set fires, with views ranging from catastrophic to negligible. Understanding of the diversity of human fire regimes on Earth in the past, present and future remains rudimentary. It remains uncertain how humans have caused a departure from 'natural' background levels that vary with climate change. Available evidence shows that modern humans can increase or decrease background levels of natural fire activity by clearing forests, promoting grazing, dispersing plants, altering ignition patterns and actively suppressing fires, thereby causing substantial ecosystem changes and loss of biodiversity. Some of these contemporary fire regimes cause substantial economic disruptions owing to the destruction of infrastructure, degradation of ecosystem services, loss of life, and smoke-related health effects. These episodic disasters help frame negative public attitudes towards landscape fires, despite the need for burning to sustain some ecosystems. Greenhouse gas-induced warming and changes in the hydrological cycle may increase the occurrence of large, severe fires, with potentially significant feedbacks to the Earth system. Improved understanding of human fire regimes demands: (1) better data on past and current human influences on fire regimes to enable global comparative analyses, (2) a greater understanding of different cultural traditions of landscape burning and their positive and negative social, economic and ecological effects, and (3) more realistic representations of anthropogenic fire in global vegetation and climate change models. We provide an historical framework to promote understanding of the development and diversification of fire regimes, covering the pre-human period, human domestication of fire, and the subsequent transition from subsistence agriculture to industrial economies. All of these phases still occur on Earth, providing opportunities for comparative research.

Severity of an uncharacteristically large wildfire, the Rim Fire, in forests with relatively restored frequent fire regimes

Treesearch

Jamie Lydersen; Malcolm North; Brandon M. Collins

2014-01-01

The 2013 Rim Fire, originating on Forest Service land, burned into old-growth forests within Yosemite National Park with relatively restored frequent-fire regimes (¡Ý2 predominantly low and moderate severity burns within the last 35 years). Forest structure and fuels data were collected in the field 3-4 years before the fire, providing a rare chance to use pre-existing...

Pre-fire treatments have persistent effects on post-fire plant communities

Treesearch

Kristen L. Shive

2012-01-01

Wildfires characterized by large areas of high severity are increasingly occurring in ponderosa pine (Pinus ponderosa P. & C. Lawson) forests of the Southwest to extents that are out of the natural range of variability. Managers are now routinely applying thinning and/or burning treatments to reduce fire severity. To investigate the effects of pre-fire treatments...

Fire Severity and Intensity During Spring Burning in Natural and Masticated Mixed Shrub Woodlands

Treesearch

Tim Bradley; Jennifer Gibson; Windy Bunn

2006-01-01

Fire risk is an ever present management concern in many urban interface regions. To mitigate this risk, land management agencies have expanded their options beyond prescribed fire to include vegetation mastication and other mechanical fuel treatments. This research project examined fire severity and intensity in masticated and unmanipulated units that were burned in...

Fires following bark beetles: Factors controlling severity and disturbance interactions in ponderosa pine

Treesearch

Carolyn H. Sieg; Rodman R. Linn; Francois Pimont; Chad M. Hoffman; Joel D. McMillin; Judith Winterkamp; L. Scott Baggett

2017-01-01

Previous studies have suggested that bark beetles and fires can be interacting disturbances, whereby bark beetle-caused tree mortality can alter the risk and severity of subsequent wildland fires. However, there remains considerable uncertainty around the type and magnitude of the interaction between fires following bark beetle attacks, especially in drier forest types...

78 FR 8058 - Airworthiness Directives; Fokker Services B.V. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-05

... torque values of nuts on circuit breakers, contactors, and terminal blocks of the electrical power center... loose nuts, which could result in arcing and potentially an onboard fire, possibly resulting in damage... were issued, several operators reported finding loose nuts on contactors in the EPC of Fokker 50/60...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tom Elicson; Bentley Harwood; Jim Bouchard

Over a 12 month period, a fire PRA was developed for a DOE facility using the NUREG/CR-6850 EPRI/NRC fire PRA methodology. The fire PRA modeling included calculation of fire severity factors (SFs) and fire non-suppression probabilities (PNS) for each safe shutdown (SSD) component considered in the fire PRA model. The SFs were developed by performing detailed fire modeling through a combination of CFAST fire zone model calculations and Latin Hypercube Sampling (LHS). Component damage times and automatic fire suppression system actuation times calculated in the CFAST LHS analyses were then input to a time-dependent model of fire non-suppression probability. Themore » fire non-suppression probability model is based on the modeling approach outlined in NUREG/CR-6850 and is supplemented with plant specific data. This paper presents the methodology used in the DOE facility fire PRA for modeling fire-induced SSD component failures and includes discussions of modeling techniques for: • Development of time-dependent fire heat release rate profiles (required as input to CFAST), • Calculation of fire severity factors based on CFAST detailed fire modeling, and • Calculation of fire non-suppression probabilities.« less

Fire investigation

NASA Astrophysics Data System (ADS)

Gomberg, A.

There was considerable progress made on several fronts of fire investigation in the United States in recent years. Progress was made in increasing the quantity of fire investigation and reporting, through efforts to develop the National Fire Incident Reporting System. Improving overall quality of fire investigation is the objective of efforts such as the Fire Investigation Handbook, which was developed and published by the National Bureau of Standards, and the upgrading and expanding of the ""dictionary'' of fire investigation and reporting, the NFPA 901, Uniform Coding for Fire Protection, system. The science of fire investigation as furthered also by new approaches to post fire interviews being developed at the University of Washington, and by in-depth research into factors involved in several large loss fires, including the MGM Grand Hotel in Las Vegas. Finally, the use of special study fire investigations - in-depth investigations concentrating on specific fire problems - is producing new glimpses into the nature of the national fire problem. A brief description of the status of efforts in each of these areas is discussed.

The effects of fire severity on black carbon additions to forest soils - 10 years post fire

NASA Astrophysics Data System (ADS)

Poore, R.; Wessman, C. A.; Buma, B.

2013-12-01

Wildfires play an active role in the global carbon cycle. While large amounts of carbon dioxide are released, a small fraction of the biomass consumed by the fire is only partially combusted, yielding soot and charcoal. These products, also called black carbon (BC) make up only 1-5% of the biomass burnt, yet they can have a disproportionate effect on both the atmosphere and fluxes in long-term carbon pools. This project specifically considers the fraction that is sequestered in forest soils. Black carbon is not a specific compound, and exists along a continuum ranging from partially burned biomass to pure carbon or graphite. Increasing aromaticity as the result of partial combustion means charcoal is highly resistant to oxidation. Although debated, most studies indicate a turnover time on the order of 500-1,000 years in warm, wet, aerobic soils. Charcoal may function as a long-term carbon sink, however its overall significance depends on its rate of formation and loss. At the landscape level, fire characteristics are one of the major factors controlling charcoal production. A few studies suggest that charcoal production increases with cooler, less-severe fires. However, there are many factors to tease apart, partly because of a lack of specificity in how fire severity is defined. Within this greater context, our lab has been working on a landscape-level study within Routt National Forest, north of Steamboat Springs, Colorado. In 2002, a large fire swept through a subalpine spruce, fir and lodgepole pine forest. In 2011-2013 we sampled BC pools in 44 plots across a range of fire severities from unburned to severe crown We hypothesized that charcoal stocks will be higher in areas of low severity fire as compared to high severity because of decreased re-combustion of charcoal in the organic soil and increased overall charcoal production due to lower temperatures. In each of our plots we measured charcoal on snags and coarse woody debris, sampled the entire organic horizon and the top 10cm mineral horizon. The soils were sieved to 2mm and their BC content measured using the Kurth-MacKenzie-DeLuca method of digesting labile carbon using nitric acid and hydrogen peroxide at 95C for 20hrs. We integrated both remotely sensed data and field observations. We used the Relative Difference Normalized Burn Ratio (RdNBR) calculated by Monitoring Trends in Burn Severity (MTBS). This index used Landsat images from July in the years before and after the fire and is based on differences in bands 4 and 7, with the aim of assessing coarse scale changes in soil and vegetation post fire. For each plot we also collected data on tree mortality and organic soil depth. These metrics were chosen from the Composite Burn Index as those that were most reliable even 10 years after the fire. We observed no significant differences in BC totals between high severity fire and unburned plots, although BC increased slightly on burned plots. Early results for low severity sites (analysis still in progress) suggest that BC increased in plots experiencing lower severity fires compared to unburned and high severity plots. Comparing carbon and BC totals on unburned and severely burned plots, and assuming no loss of BC from mineral soil during the fire, we observed a 1.2% conversion of burned biomass to BC, which corresponds with literature estimates of 1-4%.

Strategies for preventing invasive plant outbreaks after prescribed fire in ponderosa pine forest

USGS Publications Warehouse

Symstad, Amy J.; Newton, Wesley E.; Swanson, Daniel J.

2014-01-01

Land managers use prescribed fire to return a vital process to fire-adapted ecosystems, restore forest structure from a state altered by long-term fire suppression, and reduce wildfire intensity. However, fire often produces favorable conditions for invasive plant species, particularly if it is intense enough to reveal bare mineral soil and open previously closed canopies. Understanding the environmental or fire characteristics that explain post-fire invasive plant abundance would aid managers in efficiently finding and quickly responding to fire-caused infestations. To that end, we used an information-theoretic model-selection approach to assess the relative importance of abiotic environmental characteristics (topoedaphic position, distance from roads), pre-and post-fire biotic environmental characteristics (forest structure, understory vegetation, fuel load), and prescribed fire severity (measured in four different ways) in explaining invasive plant cover in ponderosa pine forest in South Dakota’s Black Hills. Environmental characteristics (distance from roads and post-fire forest structure) alone provided the most explanation of variation (26%) in post-fire cover of Verbascum thapsus (common mullein), but a combination of surface fire severity and environmental characteristics (pre-fire forest structure and distance from roads) explained 36–39% of the variation in post-fire cover of Cirsium arvense (Canada thistle) and all invasives together. For four species and all invasives together, their pre-fire cover explained more variation (26–82%) in post-fire cover than environmental and fire characteristics did, suggesting one strategy for reducing post-fire invasive outbreaks may be to find and control invasives before the fire. Finding them may be difficult, however, since pre-fire environmental characteristics explained only 20% of variation in pre-fire total invasive cover, and less for individual species. Thus, moderating fire intensity or targeting areas of high severity for post-fire invasive control may be the most efficient means for reducing the chances of post-fire invasive plant outbreaks when conducting prescribed fires in this region.

Western Spruce Budworm Outbreaks Did Not Increase Fire Risk over the Last Three Centuries: A Dendrochronological Analysis of Inter-Disturbance Synergism

PubMed Central

Flower, Aquila; G. Gavin, Daniel; Heyerdahl, Emily K.; Parsons, Russell A.; Cohn, Gregory M.

2014-01-01

Insect outbreaks are often assumed to increase the severity or probability of fire occurrence through increased fuel availability, while fires may in turn alter susceptibility of forests to subsequent insect outbreaks through changes in the spatial distribution of suitable host trees. However, little is actually known about the potential synergisms between these natural disturbances. Assessing inter-disturbance synergism is challenging due to the short length of historical records and the confounding influences of land use and climate changes on natural disturbance dynamics. We used dendrochronological methods to reconstruct defoliator outbreaks and fire occurrence at ten sites along a longitudinal transect running from central Oregon to western Montana. We assessed synergism between disturbance types, analyzed long-term changes in disturbance dynamics, and compared these disturbance histories with dendroclimatological moisture availability records to quantify the influence of moisture availability on disturbances. After approximately 1890, fires were largely absent and defoliator outbreaks became longer-lasting, more frequent, and more synchronous at our sites. Fires were more likely to occur during warm-dry years, while outbreaks were most likely to begin near the end of warm-dry periods. Our results show no discernible impact of defoliation events on subsequent fire risk. Any effect from the addition of fuels during defoliation events appears to be too small to detect given the overriding influence of climatic variability. We therefore propose that if there is any relationship between the two disturbances, it is a subtle synergistic relationship wherein climate determines the probability of occurrence of each disturbance type, and each disturbance type damps the severity, but does not alter the probability of occurrence, of the other disturbance type over long time scales. Although both disturbance types may increase in frequency or extent in response to future warming, our records show no precedent that western spruce budworm outbreaks will increase future fire risk. PMID:25526633

Western spruce budworm outbreaks did not increase fire risk over the last three centuries: a dendrochronological analysis of inter-disturbance synergism.

PubMed

Flower, Aquila; Gavin, Daniel G; Heyerdahl, Emily K; Parsons, Russell A; Cohn, Gregory M

2014-01-01

Insect outbreaks are often assumed to increase the severity or probability of fire occurrence through increased fuel availability, while fires may in turn alter susceptibility of forests to subsequent insect outbreaks through changes in the spatial distribution of suitable host trees. However, little is actually known about the potential synergisms between these natural disturbances. Assessing inter-disturbance synergism is challenging due to the short length of historical records and the confounding influences of land use and climate changes on natural disturbance dynamics. We used dendrochronological methods to reconstruct defoliator outbreaks and fire occurrence at ten sites along a longitudinal transect running from central Oregon to western Montana. We assessed synergism between disturbance types, analyzed long-term changes in disturbance dynamics, and compared these disturbance histories with dendroclimatological moisture availability records to quantify the influence of moisture availability on disturbances. After approximately 1890, fires were largely absent and defoliator outbreaks became longer-lasting, more frequent, and more synchronous at our sites. Fires were more likely to occur during warm-dry years, while outbreaks were most likely to begin near the end of warm-dry periods. Our results show no discernible impact of defoliation events on subsequent fire risk. Any effect from the addition of fuels during defoliation events appears to be too small to detect given the overriding influence of climatic variability. We therefore propose that if there is any relationship between the two disturbances, it is a subtle synergistic relationship wherein climate determines the probability of occurrence of each disturbance type, and each disturbance type damps the severity, but does not alter the probability of occurrence, of the other disturbance type over long time scales. Although both disturbance types may increase in frequency or extent in response to future warming, our records show no precedent that western spruce budworm outbreaks will increase future fire risk.

Changing Weather Extremes Call for Early Warning of Potential for Catastrophic Fire

NASA Astrophysics Data System (ADS)

Boer, Matthias M.; Nolan, Rachael H.; Resco De Dios, Víctor; Clarke, Hamish; Price, Owen F.; Bradstock, Ross A.

2017-12-01

Changing frequencies of extreme weather events and shifting fire seasons call for enhanced capability to forecast where and when forested landscapes switch from a nonflammable (i.e., wet fuel) state to the highly flammable (i.e., dry fuel) state required for catastrophic forest fires. Current forest fire danger indices used in Europe, North America, and Australia rate potential fire behavior by combining numerical indices of fuel moisture content, potential rate of fire spread, and fire intensity. These numerical rating systems lack the physical basis required to reliably quantify forest flammability outside the environments of their development or under novel climate conditions. Here, we argue that exceedance of critical forest flammability thresholds is a prerequisite for major forest fires and therefore early warning systems should be based on a reliable prediction of fuel moisture content plus a regionally calibrated model of how forest fire activity responds to variation in fuel moisture content. We demonstrate the potential of this approach through a case study in Portugal. We use a physically based fuel moisture model with historical weather and fire records to identify critical fuel moisture thresholds for forest fire activity and then show that the catastrophic June 2017 forest fires in central Portugal erupted shortly after fuels in the region dried out to historically unprecedented levels.

Fire impacts on European Boreal soils: A review

NASA Astrophysics Data System (ADS)

Pereira, Paulo; Oliva, Marc; Cerda, Artemi

2016-04-01

Fire is an important natural disturbance in boreal ecosystems, fundamental to understand plant distribution (Ryan, 2002; Wallenius et al., 2004; Granstrom, 2001). Nevertheless, nowadays the intense and successful, fire suppression measures are changing their ecological role (Pereira et al., 2013a,b). This is consequence of the lack of understanding of stakeholders and decision makers about the role of the fire in the ecosystems (Mierasukas and Pereira, 2013; Pereira et al., 2016). This fire suppression measures are increasing the amount of fuel accumulation and the risk of severe wildfires, which can increase of frequency and severity in a context of climate change. Fire is a good tool for landscape management and restoration of degraded ecosystems (Toivanen and Kotiaho, 2007). Fire is considered a soil forming factor (Certini, 2014) and in boreal environments it has been observed that low fire severities, do not change importantly soil properties, mean fire severities induce positive impacts on soil, since add an important amounts of nutrients into soil profile and high severity fires had negative impacts due to the high consumption of organic matter (Vanha-Majamaa et al., 2007; Pereira et al., 2014). References Certini, G., 2014. Fire as a soil-forming factor. Ambio, 43, 191-195 Granstrom A. 2001. Fire management for biodiversity in the European Boreal forest. Scandinavian Journal of Forest Research 3: 62-69. Mierauskas, P., Pereira, P. (2013) Stakeholders perception about prescribed fire use in Lithuania. First results, Flamma, 4(3), 157-161. Pereira, P., Cerdà, A., Jordán, A., Bolutiene, V., Úbeda, X., Pranskevicius, M., Mataix-Solera, J. (2013) Spatio-temporal vegetation recuperation after a grassland fire in Lithuania, Procedia Environmental Sciences, 19:856-864 Pereira, P., Mierauskas, P., Ubeda, X., Mataix-Solera, J.,Cerda, A. (2012) Fire in protected areas - the effect of the protection and importance of fire management, Environmental Research, Engineering and Management, 1(59), 52-62. Pereira, P., Ubeda, X., Mataix-Solera, J., Oliva, M., Novara, A. (2014) Short-term spatio-temporal spring grassland fire effects on soil colour,organic matter and water repellency in Lithuania, Solid Earth, 5, 209-225. Ryan KC. 2002. Dynamic Interactions between forest structure and fire behavioural in boreal ecosystems. Silva Fennica 36: 13-39 Toivanen T, Kotiaho JS. 2007. Mimicking natural disturbances of boreal forests: the effects of controlled burning and creating dead wood on beetle diversity. Biodiversity Conservation 16: 3193-3211.

Human Neck Response during Vertical Impact with Variable Weighted Helmets

DTIC Science & Technology

2006-09-01

activated, action potentials from the brain travel to motor neurons which branch out to the muscle fibers . EMG sensors record the action potentials of...the motor unit, comprised of several activated muscle fibers . An "EMG signal directly reflects the recruitment and firing characteristics of the...upper trapezius and SCM associated with isometric muscle contractions. They thoroughly investigated the mechanics of muscle fatigue during helmet loading

Effectiveness of mechanical thinning and prescribed burning on fire behavior in Pinus nigra forests in NE Spain.

PubMed

Piqué, Míriam; Domènech, Rut

2018-03-15

Fuel treatments can mitigate present and future impacts of climate change by reducing fire intensity and severity. In recent years, Pinus nigra forests in the Mediterranean basin have been dramatically affected by the new risk of highly intense and extreme fires and its distribution area has been reduced. New tools are necessary for assessing the management of these forests so they can adapt to the challenges to come. Our main goal was to evaluate the effects of different fuel treatments on Mediterranean Pinus nigra forests. We assessed the forest response, in terms of forest structure and fire behavior, to different intensities of low thinning treatments followed by different slash prescriptions (resulting in: light thinning and lop and scatter; light thinning and burn; heavy thinning and lop and scatter; heavy thinning and burn; and, untreated control). Treatments that used fire to decrease the resulting slash were the most effective for reducing active crown fires decreasing the rate of spread and flame length more than 89%. Low thinning had an effect on torching potential, but there was no difference between intensities of thinning. Only an outcoming crown fire could spread actively if it was sustained by a high-enough constant wind speed and enough surface fuel load. Overall, treatments reduce fire intensity and treated areas have a more homogenous fire behavior response than untreated areas. This provides opportunities to extinguish the fire and reduce the probability of trees dying from the fire. It would be helpful to include ecological principles and fire behavior criteria in silvicultural treatment guidelines in order to perform more efficient management techniques in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

Use of prescribed fire to reduce wildfire potential

Treesearch

Robert E. Martin; J. Boone Kauffman

1989-01-01

Fires were a part of our wildlands prehistorically. Prescribed burning reduces fire hazard and potential fire behavior primarily by reducing fuel quantity and continuity. Fuel continuity should be considered on the micro scale within stands, the mid-scale among, and the macro-scale among watersheds or entire forests. Prescribed fire is only one of the tools which can...

The Role of Low-severity Fire and Thermal Alteration of Soil Organic Matter in Carbon Preservation and GHG Flux From Global Peatlands

NASA Astrophysics Data System (ADS)

Flanagan, N. E.; Wang, H.; Hodgkins, S. B.; Richardson, C. J.

2017-12-01

Many global peatlands are dominated by fire-adapted plant communities and are subject to frequent wildfires with return intervals ranging between 3 to 100 years. Wildfires in peatlands are typically low-severity events that occur in winter and spring when vegetation is desiccated and soil moisture content is high. As a result, most wildfires consume aboveground fuels in a matter of minutes without igniting the nearly saturated peat. In such fires, surface soil layers are subjected to flash heating with a rapid loss of soil moisture but little loss of soil organic matter (SOM). Such fires have the potential to alter the chemical structure of SOM, even in the absence of combustion, through Maillard's Reaction and similar chemical processes, and through structural changes that protect SOM from decomposition. This study examines the effects of low-intensity surface fires on the recalcitrance of SOM from fire-adapted communities located in subtropical, temperate and sub-boreal peatlands. In addition, soil from a non-fire-adapted Peruvian palm peatland was examined for response to thermal alteration. The timing and temperatures of low-intensity fires were measured in the field during prescribed burns and replicated in simulated fires. The effects of fire on the chemical structure of SOM were examined with FTIR, SEM and XPS. Burned and unburned peat replicates were incubated at three temperatures (5oC, 15oC, 25oC) in controlled chambers for more than six months. Burned replicates initially showed higher CO2, CH4 and NO2 emissions. Yet, within four weeks emissions from the burned replicates dropped below those of unburned replicates and remained significantly lower (10-50%) for the duration of the experiment. In addition, thermal alteration significantly reduced the temperature sensitivity (Q10) of thermally altered peat. After accounting for small initial losses of organic matter (<10 %) during the fire simulations, thermal alteration of SOM resulted in a net long-term reduction in carbon losses to microbial respiration. Such thermal alteration of SOM might be an underestimated factor influencing carbon accretion in frequently burned peatlands and could be globally relevant if climate change increases fire frequency in boreal peatlands.

Post-fire Water Quality Response and Associated Physical Drivers

NASA Astrophysics Data System (ADS)

Rust, A.; Saxe, S.; Hogue, T. S.; McCray, J. E.; Rhoades, C.

2017-12-01

The frequency and severity of forest fires is increasing across the western US. Wildfires are known to impact water quality in receiving waters; many of which are important sources of water supply. Studies on individual forest fires have shown an increase in total suspended solids, nutrient and metal concentrations and loading in receiving streams. The current research looks at a large number of fires across a broad region (Western United States) to identify typical water quality changes after fire and the physical characteristics that drive those responses. This presentation will overview recent development of an extensive database on post-fire water quality. Across 172 fires, we found that water quality changed significantly in one out of three fires up to five years after the event compared to pre-burn conditions. For basins with higher frequency data, it was evident that water quality changes were significant in the first three years following fire. In both the initial years following fire and five years after fire, concentrations and loading rates of dissolved nutrients such as nitrite, nitrate and orthophosphate and particulate forms of nutrients, total organic nitrogen, total nitrogen, total phosphate, and total phosphorus increase thirty percent of the time. Concentrations of some major dissolved ions and metals decrease, with increased post-fire flows, while total particulate concentrations increased; the flux of both dissolved and particulate forms increase in thirty percent of the fires over five years. Water quality change is not uniform across the studied watersheds. A second goal of this study is to identify physical characteristics of a watershed that drive water quality response. Specifically, we investigate the physical, geochemical, and climatological characteristics of watersheds that control the type, direction, and magnitude of water quality change. Initial results reveal vegetation recovery is a key driver in post-fire water quality response. Ultimately, improved understanding of post-fire response and related drivers will advance potential mitigation and treatment strategies as well as aid in the parametrization of post-fire models of water quality.

The influence of wildfire severity on soil char composition and nitrogen dynamics

NASA Astrophysics Data System (ADS)

Rhoades, Charles; Fegel, Timothy; Chow, Alex; Tsai, Kuo-Pei; Norman, John, III; Kelly, Eugene

2017-04-01

Forest fires cause lasting ecological changes and alter the biogeochemical processes that control stream water quality. Decreased plant nutrient uptake is the mechanism often held responsible for lasting post-fire shifts in nutrient supply and demand, though other upland and in-stream factors also likely contribute to elevated stream nutrient losses. Soil heating, for example, creates pyrogenic carbon (C) and char layers that influence C and nitrogen (N) cycling. Char layer composition and persistence vary across burned landscapes and are influenced first by fire behavior through the temperature and duration of combustion and then by post-fire erosion. To evaluate the link between soil char and stream C and N export we studied areas burned by the 2002 Hayman Fire, the largest wildfire in Colorado, USA history. We compared soil C and N pools and processes across ecotones that included 1) unburned forests, 2) areas with moderate and 3) high wildfire severity. We analyzed 1-2 cm thick charred organic layers that remain visible 15 years after the fire, underlying mineral soils, and soluble leachate from both layers. Unburned soils released more dissolved organic C and N (DOC and DON) from organic and mineral soil layers than burned soils. The composition of DOC leachate characterized by UV-fluorescence, emission-excitation matrices (EEMs) and Fluorescence Regional Integration (FRI) found similarity between burned and unburned soils, underscoring a common organic matter source. Humic and fulvic acid-like fractions, contained in regions V and III of the FRI model, comprised the majority of the fluorescing DOM in both unburned and char layers. Similarity between two EEMs indices (Fluorescence and Freshness), further denote that unburned soils and char layers originate from the same source and are consistent with visual evidence char layers contain significant amounts of unaltered OM. However, the EEMs humification index (HIX) and compositional analysis with pyrolysis GCMS both indicate that C contained or leached from severely-burned char layers has higher aromaticity and thus chemical stability compared to C in unburned soils. Mineral soil (0-5 cm depth) beneath char layers in high severity portions of the Hayman Fire had significantly more soil N and C and lower pH. Potential net mineralization - an index of the supply of plant-available nitrogen - differed between the severely-burned areas and both unburned and moderately-burn areas. Negative net mineralization in unburned and moderately burned soils indicates immobilization or retention of inorganic N by soil microbes. In contrast, soils burned at high severity produced inorganic N sources available to plants, leaching and gas losses. Water soluble nitrate comprised a larger proportion of inorganic N leached from the char layer of high severity burns. Mineral soil in those areas had both higher water soluble nitrate and total inorganic N in leachate. Char layers that have persisted for fifteen years influence soil N turnover within the Hayman Fire affected area and may contribute to elevated N losses in streams burned at high severity. The chemical stability of soil char layers perpetuates their importance for C sequestration and N dynamics in burned landscapes.

The Application of a WEPP Technology to a Complex Watershed Analysis

NASA Astrophysics Data System (ADS)

Elliot, William; Miller, Ina Sue; Dobre, Mariana

2017-04-01

Forest restoration activities are essential in many forest stands, where previous management and fire suppression has resulted in stands with high density, diseased trees and excessive fuel loads. Trying to balance the watershed impacts of restoration activities such as thinning, selective harvesting, and prescribed fire against the significant impact of wildfire is challenging. The process is further aggravated by the necessity of a road network if management activities include timber removal. We propose to present an approach to a watershed analysis for a 3400-ha of fuel reduction project within an 18,0000-ha sensitive watershed in the Nez Perce National Forest in Northern Idaho, USA. The FlamMap fire spread model was first used to predict the distribution of potential fire severity on the landscape for the current fuel load, and for a landscape that had been treated by thinning and/or prescribed fire. FlamMap predicts the flame length by 30-m pixel as a function of fuel load and water content, wind speed, and slope steepness and aspect. The flame length distribution was then classified so that the distribution of burn severity (unburned, low, moderate and high severity) was similar to the distributions observed on recent wildfires in the Forest. The flame length classes determined for the current fuel loads were also used for the treated condition flame lengths, where predominantly unburned or low severity fire severities were predicted. The burn severity maps were uploaded to a web site that was developed to provide soil and management files reflecting burn severity and soil texture, formatted for the Geospatial interface to the Water Erosion Prediction Project (GeoWEPP). The study area was divided into 40 sub watersheds under 2.5 km2 each for GeoWEPP analysis. GeoWEPP was run for an undisturbed forest; for the burn severity following wildfire for the current and treated fuel loads; for prescribed fire, either broadcast or jack pot burn; and for thinning either by tractor or by skyline logging. The GeoWEPP erosion estimates by hillslope polygon were merged with the proposed treatment polygons to produce maps of erosion for each condition for each treatment polygon. Road network erosion was estimated using a new online GIS tool to estimate road segment length and steepness, and linking those topographic values to the WEPP model for erosion prediction by road segment. The results were summarized and compared to earlier estimates of sediment delivery using a locally-developed cumulative watershed effects analysis. The results were similar from both tools, in spite of using very different erosion estimation methods, and similar to regional observations of forest watershed sediment delivery ( 12.5 Mg/sq km). The study found that the erosion risk from wildfire was 5 times greater than sediment generated by forest management, justifying the proposed restoration activities to reduce fire risk. Sediment generated from the road network, however, was unacceptably high suggesting that methods improve road erosion prediction and/or to reduce road erosion are warranted.

Land surveys show regional variability of historical fire regimes and dry forest structure of the western United States.

PubMed

Baker, William L; Williams, Mark A

2018-03-01

An understanding of how historical fire and structure in dry forests (ponderosa pine, dry mixed conifer) varied across the western United States remains incomplete. Yet, fire strongly affects ecosystem services, and forest restoration programs are underway. We used General Land Office survey reconstructions from the late 1800s across 11 landscapes covering ~1.9 million ha in four states to analyze spatial variation in fire regimes and forest structure. We first synthesized the state of validation of our methods using 20 modern validations, 53 historical cross-validations, and corroborating evidence. These show our method creates accurate reconstructions with low errors. One independent modern test reported high error, but did not replicate our method and made many calculation errors. Using reconstructed parameters of historical fire regimes and forest structure from our validated methods, forests were found to be non-uniform across the 11 landscapes, but grouped together in three geographical areas. Each had a mixture of fire severities, but dominated by low-severity fire and low median tree density in Arizona, mixed-severity fire and intermediate to high median tree density in Oregon-California, and high-severity fire and intermediate median tree density in Colorado. Programs to restore fire and forest structure could benefit from regional frameworks, rather than one size fits all. © 2018 by the Ecological Society of America.

Mixed-severity fire regimes in dry forests of southern interior British Columbia, Canada

Treesearch

Emily K. Heyerdahl; Ken Lertzman; Carmen M. Wong

2012-01-01

Historical fire severity is poorly characterized for dry forests in the interior west of North America. We inferred a multicentury history of fire severity from tree rings in Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) - ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) forests in the southern interior of British Columbia,...

Quantifying fire severity, carbon, and nitrogen emissions in Alaska's boreal forest

Treesearch

Leslie A. Boby; Edward A.G. Schuur; Michelle C. Mack; David Verbyla; Jill F. Johnstone

2010-01-01

The boreal region stores a large proportion of the world's terrestrial carbon (C) and is subject to high-intensity, stand-replacing wildfires that release C and nitrogen (N) stored in biomass and soils through combustion. While severity and extent of fires drives overall emissions, methods for accurately estimating fire severity are poorly tested in this unique...

Wildfires and geochemical change in a subalpine forest over the past six millennia

NASA Astrophysics Data System (ADS)

Leys, Bérangère; Higuera, Philip E.; McLauchlan, Kendra K.; Dunnette, Paul V.

2016-12-01

The frequency of large wildfires in western North America has been increasing in recent decades, yet the geochemical impacts of these events are poorly understood. The multidecadal timescales of both disturbance-regime variability and ecosystem responses make it challenging to study the effects of fire on terrestrial nutrient cycling. Nonetheless, disturbance-mediated changes in nutrient concentrations could ultimately limit forest productivity over centennial to millennial time scales. Here, we use a novel approach that combines quantitative elemental analysis of lake sediments using x-ray fluorescence to assess the geochemical impacts of high-severity fires in a 6200 year long sedimentary record from a small subalpine lake in Rocky Mountain National Park, Colorado, USA. Immediately after 17 high-severity fires, the sedimentary concentrations of five elements increased (Ti, Ca, K, Al, and P), but returned to pre-fire levels within three decades. Multivariate analyses indicate that erosion of weathered mineral material from the catchment is a primary mechanism though which high-severity fires impact element cycling. A longer-term trend in sediment geochemistry was also identified over millennial time scales. This decrease in the concentrations of six elements (Al, Si, K, Ti, Mn, and Fe) over the past 6200 years may have been due to a decreased rate of high-severity fires, long-term ecosystem development, or changes in precipitation regime. Our results indicate that high-severity fire events can determine elemental concentrations in subalpine forests. The degree of variability in geochemical response across time scales suggests that shifting rates of high-severity burning can cause significant changes in key rock-derived nutrients. To our knowledge, these results are the first to reveal repeated loss of rock-derived nutrients from the terrestrial ecosystem due to high-severity fires. Understanding the future of fire-prone coniferous forests requires further documentation and quantification of this important mechanism linking fire regimes and biogeochemical cycles.

Post-fire ecosystem recovery trajectories along burn severity gradients

NASA Astrophysics Data System (ADS)

Newingham, B. A.; Hudak, A. T.; Bright, B. C.; Smith, A. G.; Henareh Khalyani, A.

2017-12-01

Burn severity is a term used to describe the longer-term, second-order effects of fire on ecosystems. Plant communities are assumed to recover more slowly at higher burn severities; however, this likely depends on plant community type and climate. We assessed vegetation recovery approximately a decade post-fire across North American forests (moist mixed conifer, dry mixed conifer, ponderosa pine) and shrublands (mountain big sagebrush and Wyoming big sagebrush) distributed across climate and burn severity gradients. We assessed vegetation recovery across these ecosystems as indicated by the differenced Normalized Burn Ratio derived from 1984-2016 Landsat time series imagery (LandTrendr). Additionally, we used field vegetation measurements to examine local topographic controls on burn severity and post-fire vegetation recovery. Ecosystem responses were related to climate predictors derived from downscaled 1993-2011 climate normals. We hypothesized that drier and hotter ecosystems would take longer to recover. We also predicted areas with higher burn severity to have slower recovery. We found post-fire recovery to be strongly predicted by precipitation with the slowest recovery in shrublands and ponderosa pine forest, the driest vegetation types considered. We conclude that climate and burn severity interact to determine ecosystem recovery trajectories after fire, with burn severity having larger influence in the short term, and climate having larger influence in the long term.

Fire and Emission Characterization in the Northern Sub-Saharan Africa (NSSA) Region and their Potential Effects on the Regional Climate System

NASA Astrophysics Data System (ADS)

Ellison, L.; Ichoku, C. M.

2013-12-01

Northern Sub-Saharan Africa (NSSA) is known for its consistent vast amounts of seasonal biomass burning each year. These mostly anthropogenic slash-and-burn fires typically used for farming and grazing purposes contributes to a significant proportion of the total global emissions of particulate matter (PM). The consequences of such severe burning could potentially have a noticeable influence on local climate patterns, such as the frequent severe droughts over the past century or the drying of Lake Chad, through both direct and indirect causes. This research therefore focuses on: 1) characterizing the burning patterns and extent within NSSA, 2) accurately quantifying PM emissions that have a direct impact on climate, and 3) exploring potential indirect impacts of burning on climate through evaluation of correlations with various environmental and meteorological parameters. In this study, the NSSA region was first split into nine distinct sub-regions to better analyze the burning patters and climatological changes. The diurnal cycle of fire radiative power (FRP, a quantifiable way of measuring fire radiant heat output) within these different regions differ in amplitude and shape, though the basic shape is the same with months of maximum FRP being between November and January and with practically no fires during the rainy season. Corresponding changes in other climatological variables were studied against changes seen in FRP on a monthly scale, including precipitation, soil moisture, surface evaporation, evapotranspiration (ET), normalized difference vegetation index (NDVI) and aerosol optical depth (AOD). This study includes an analysis of the distinct change in FRP signal that occurred in 2006 for the middle of the NSSA region, which is the area with the highest concentration of fires. A decrease in maximum monthly FRP has been observed since 2006 in this region. Regional changes in PM emissions have also been observed since then, including a large region of decreasing emissions southwest of Lake Chad. These emissions are taken from the new Fire Energetics and Emissions Research (FEER) emissions product that was developed as part of this NSSA research and is based on a global coefficient of emission (Ce) map with high spatial resolution. The FEER algorithm is a top-down approach in an effort to properly account for all emitted PM, which is especially important in the NSSA region because of its high concentration of fire events. When the FEER Ce v1.0 product is combined with the global FRP dataset from the Global Fire Assimilation System (GFAS) v1.0 product to generate PM emissions, estimates of total particulate matter (TPM) are generated. The FEER product estimates average annual TPM emissions in the NSSA region to be around 14 Tg between 2004-2010, which is greater than GFAS v1.0 by a factor of 1.8, and greater than the Global Fire Emissions Database (GFED) v3.1 by a factor of 1.6. Future work will plug these new emission estimates into regional models to gain a better understanding of the impacts of biomass burning on climate in NSSA.

Burning transformations: Fire history effects on organic matter processing from hillslopes to streams

NASA Astrophysics Data System (ADS)

Barnes, R. T.; Gilbertson, A.; Maxwell, K.

2017-12-01

Disturbance strongly regulates material and energy flows, changing ecosystem pattern and process. An increase in the size and severity of fire, particularly in the Intermountain West, over the last several decades is expected to continue due to a warming climate. Predicting how fire will alter the net ecosystem carbon balance requires us to understand how carbon is stored, processed, and transferred. Here we present results from paired watersheds focused on five 2002 severe fires in Colorado to examine how organic matter is processed along the hillslope and within the stream. Comparing soil samples and water extractable organic matter (WEOM) between burned and unburned sites illustrates the impact of fire: burned soils have 50% organic matter (OM) content as unburned soils, regardless of geomorphic position. While a smaller pool, soil OM (SOM) in burned sites is more susceptible to microbial degradation (p<0.001 for 4 of 6 sites), especially in systems with slower vegetative recovery. This is explained, in part, to the water extractable organic matter (WEOM) from unburned soils having a higher C:N than burned sites (p<0.02). This shift in SOM quality is likely due to differing OM inputs (e.g. grasses and forbes vs. trees in burned vs. unburned sites). Comparing results from intact soil column experiments to soil extractions and stream samples, suggests that the majority of this soil derived WEOM does not make it to the stream, potentially getting sorbed deeper in the mineral rich, organic poor, portion of the soil. Interestingly, the systematic shifts in OM amounts and quality (as measured by SUVA, E2:E3, and fluorescence) within the terrestrial system in response to fire, are not seen in stream exports. As such, while there are significant relationships (p<0.05) between stream DOM quality, DOM bioavailability, and stream metabolism, burned watersheds are not exporting DOM that is more bioavailable. In addition, despite different terrestrial OM pools, burned and unburned watersheds export statistically similar amounts of DOM per unit area, suggesting that a larger fraction of OM is transferred from the terrestrial to aquatic ecosystem within fire affected landscapes.

Persistent Effects of Fire Severity on Early Successional Forests in Interior Alaska

NASA Technical Reports Server (NTRS)

Shenoy, Aditi; Johnstone, Jill F.; Kasischke, Eric S.; Kielland, Knut

2011-01-01

There has been a recent increase in the frequency and extent of wildfires in interior Alaska, and this trend is predicted to continue under a warming climate. Although less well documented, corresponding increases in fire severity are expected. Previous research from boreal forests in Alaska and western Canada indicate that severe fire promotes the recruitment of deciduous tree species and decreases the relative abundance of black spruce (Picea mariana) immediately after fire. Here we extend these observations by (1) examining changes in patterns of aspen and spruce density and biomass that occurred during the first two decades of post-fire succession, and (2) comparing patterns of tree composition in relation to variations in post-fire organic layer depth in four burned black spruce forests in interior Alaska after 10-20 years of succession.Wefound that initial effects of fire severity on recruitment and establishment of aspen and black spruce were maintained by subsequent effects of organic layer depth and initial plant biomass on plant growth during post-fire succession. The proportional contribution of aspen (Populus tremuloides) to total stand biomass remained above 90% during the first and second decades of succession in severely burned sites, while in lightly burned sites the proportional contribution of aspen was reduced due to a 40- fold increase in spruce biomass in these sites. Relationships between organic layer depth and stem density and biomass were consistently negative for aspen, and positive or neutral for black spruce in all four burns. Our results suggest that initial effects of post-fire organic layer depths on deciduous recruitment are likely to translate into a prolonged phase of deciduous dominance during post-fire succession in severely burned stands. This shift in vegetation distribution has important implications for climate-albedo feedbacks, future fire regime, wildlife habitat quality and natural resources for indigenous subsistence activities in interior Alaska.

Application of the NUREG/CR-6850 EPRI/NRC Fire PRA Methodology to a DOE Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tom Elicson; Bentley Harwood; Richard Yorg

2011-03-01

The application NUREG/CR-6850 EPRI/NRC fire PRA methodology to DOE facility presented several challenges. This paper documents the process and discusses several insights gained during development of the fire PRA. A brief review of the tasks performed is provided with particular focus on the following: • Tasks 5 and 14: Fire-induced risk model and fire risk quantification. A key lesson learned was to begin model development and quantification as early as possible in the project using screening values and simplified modeling if necessary. • Tasks 3 and 9: Fire PRA cable selection and detailed circuit failure analysis. In retrospect, it wouldmore » have been beneficial to perform the model development and quantification in 2 phases with detailed circuit analysis applied during phase 2. This would have allowed for development of a robust model and quantification earlier in the project and would have provided insights into where to focus the detailed circuit analysis efforts. • Tasks 8 and 11: Scoping fire modeling and detailed fire modeling. More focus should be placed on detailed fire modeling and less focus on scoping fire modeling. This was the approach taken for the fire PRA. • Task 14: Fire risk quantification. Typically, multiple safe shutdown (SSD) components fail during a given fire scenario. Therefore dependent failure analysis is critical to obtaining a meaningful fire risk quantification. Dependent failure analysis for the fire PRA presented several challenges which will be discussed in the full paper.« less

Evidence of fuels management and fire weather influencing fire severity in an extreme fire event

Treesearch

Jamie M. Lydersen; Brandon M. Collins; Matthew L. Brooks; John R. Matchett; Kristen L. Shive; Nicholas A. Povak; Van R. Kane; Douglas F. Smith

2017-01-01

Following changes in vegetation structure and pattern, along with a changing climate, large wildfire incidence has increased in forests throughout the western U.S. Given this increase there is great interest in whether fuels treatments and previous wildfire can alter fire severity patterns in large wildfires. We assessed the relative influence of previous fuels...

Challenges of assessing fire and burn severity using field measures, remote sensing and modelling

Treesearch

Penelope Morgan; Robert E. Keane; Gregory K. Dillon; Theresa B. Jain; Andrew T. Hudak; Eva C. Karau; Pamela G. Sikkink; Zachery A. Holden; Eva K. Strand

2014-01-01

Comprehensive assessment of ecological change after fires have burned forests and rangelands is important if we are to understand, predict and measure fire effects. We highlight the challenges in effective assessment of fire and burn severity in the field and using both remote sensing and simulation models. We draw on diverse recent research for guidance on assessing...

Mapping day-of-burning with coarse-resolution satellite fire-detection data

Treesearch

Sean A. Parks

2014-01-01

Evaluating the influence of observed daily weather on observed fire-related effects (e.g. smoke production, carbon emissions and burn severity) often involves knowing exactly what day any given area has burned. As such, several studies have used fire progression maps ­ in which the perimeter of an actively burning fire is mapped at a fairly high temporal resolution -...

A comparison of effects from prescribed fires and wildfires managed for resource objectives in Sequoia and Kings Canyon National Parks

USGS Publications Warehouse

Nesmith, C.B.; Caprio, Anthony C.; Pfaff, Anne H.; McGinnis, Thomas W.; Keeley, Jon E.

2011-01-01

Current goals for prescription burning are focused on measures of fuel consumption and changes in forest density. These benchmarks, however, do not address the extent to which prescription burning meets perceived ecosystem needs of heterogeneity in burning, both for overstory trees and understory herbs and shrubs. There are still questions about how closely prescribed fires mimic these patterns compared to natural wildfires. This study compared burn patterns of prescribed fires and managed unplanned wildfires to understand how the differing burning regimes affect ecosystem properties. Measures of forest structure and fire severity were sampled in three recent prescribed fires and three wildfires managed for resource objectives in Sequoia and Kings Canyon National Parks. Fine scale patterns of fire severity and heterogeneity were compared between fire types using ground-based measures of fire effects on fuels and overstory and understory vegetation. Prescribed fires and wildfires managed for resource objectives displayed similar patterns of overstory and understory fire severity, heterogeneity, and seedling and sapling survival. Variation among plots within the same fire was always greater than between fire types. Prescribed fires can provide burned landscapes that approximate natural fires in many ways. It is recognized that constraints placed on when wildfires managed for resource objectives are allowed to burn freely may bias the range of conditions that might have been experienced under more natural conditions. Therefore they may not exactly mimic natural wildfires. Overall, the similarity in fire effects that we observed between prescribed fires and managed wildfires indicate that despite the restrictions that are often placed on prescribed fires, they appear to be creating post-fire conditions that approximate natural fires when assessed on a fine spatial scale.

Post-fire reconstructions of fire intensity from fire severity data: quantifying the role of spatial variability of fire intensity on forest dynamics

NASA Astrophysics Data System (ADS)

Baker, Patrick; Oborne, Lisa

2015-04-01

Large, high-intensity fires have direct and long-lasting effects on forest ecosystems and present a serious threat to human life and property. However, even within the most catastrophic fires there is important variability in local-scale intensity that has important ramifications for forest mortality and regeneration. Quantifying this variability is difficult due to the rarity of catastrophic fire events, the extreme conditions at the time of the fires, and their large spatial extent. Instead fire severity is typically measured or estimated from observed patterns of vegetation mortality; however, differences in species- and size-specific responses to fires often makes fire severity a poor proxy for fire intensity. We developed a statistical method using simple, plot-based measurements of individual tree mortality to simultaneously estimate plot-level fire intensity and species-specific mortality patterns as a function of tree size. We applied our approach to an area of forest burned in the catastrophic Black Saturday fires that occurred near Melbourne, Australia, in February 2009. Despite being the most devastating fire in the past 70 years and our plots being located in the area that experienced some of the most intense fires in the 350,000 ha fire complex, we found that the estimated fire intensity was highly variable at multiple spatial scales. All eight tree species in our study differed in their susceptibility to fire-induced mortality, particularly among the largest size classes. We also found that seedling height and species richness of the post-fire seedling communities were both positively correlated with fire intensity. Spatial variability in disturbance intensity has important, but poorly understood, consequences for the short- and long-term dynamics of forests in the wake of catastrophic wildfires. Our study provides a tool to estimate fire intensity after a fire has passed, allowing new opportunities for linking spatial variability in fire intensity to forest ecosystem dynamics.

Estimating evapotranspiration change due to forest treatment and fire at the basin scale in the Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Roche, J. W.; Goulden, M.; Bales, R. C.

2017-12-01

Increased forest evapotranspiration (ET) coupled with snowpack decreases in a warming climate is likely to decrease runoff and increase forest drought stress. Field experiments and modeling suggest that forest thinning can reduce ET and thus increase potential runoff relative to untreated areas. We investigated the potential magnitude and duration of ET decreases resulting from forest-thinning treatments and fire using a robust empirical relation between Landsat-derived mean-annual normalized difference vegetation index (NDVI) and annual ET measured at flux towers. Among forest treatments, the minimum observed NDVI change required to produce a significant departure from control plots with NDVI of about 0.70 was -0.07 units, corresponding to a basal-area reduction of 3.1 m2 ha-1, and equivalent to an estimated ET reduction of -102 mm yr-1. Intensive thinning in highly productive forests that approached pre-fire-exclusion densities reduced basal area by 40-50%, generating estimated ET reductions of 152-216 mm yr-1 over five years following treatment. Between 1990 and 2008, fires in the American River basin generated more than twice the ET reduction per unit area than those in the Kings River basin, corresponding to greater water and energy limitations in the latter and greater fire severity in the former. A rough extrapolation of these results to the entire American River watershed, much of which would have burned naturally during this 19-year period, could result in ET reductions that approach 10% of full natural flows for drought years and 5% averaged over all years. This work demonstrates the potential utility to estimate forest ET change at the patch scale, which in turn may allow managers to estimate thinning benefits in areas lacking detailed hydrologic measurements.

Synergy between land use and climate change increases future fire risk in Amazon forests

DOE PAGES

Le Page, Yannick; Morton, Douglas; Hartin, Corinne; ...

2017-12-20

Tropical forests have been a permanent feature of the Amazon basin for at least 55 million years, yet climate change and land use threaten the forest's future over the next century. Understory forest fires, which are common under the current climate in frontier forests, may accelerate Amazon forest losses from climate-driven dieback and deforestation. Far from land use frontiers, scarce fire ignitions and high moisture levels preclude significant burning, yet projected climate and land use changes may increase fire activity in these remote regions. Here, we used a fire model specifically parameterized for Amazon understory fires to examine the interactionsmore » between anthropogenic activities and climate under current and projected conditions. In a scenario of low mitigation efforts with substantial land use expansion and climate change – Representative Concentration Pathway (RCP) 8.5 – projected understory fires increase in frequency and duration, burning 4–28 times more forest in 2080–2100 than during 1990–2010. In contrast, active climate mitigation and land use contraction in RCP4.5 constrain the projected increase in fire activity to 0.9–5.4 times contemporary burned area. Importantly, if climate mitigation is not successful, land use contraction alone is very effective under low to moderate climate change, but does little to reduce fire activity under the most severe climate projections. These results underscore the potential for a fire-driven transformation of Amazon forests if recent regional policies for forest conservation are not paired with global efforts to mitigate climate change.« less

Multi-trophic resilience of boreal lake ecosystems to forest fires

USGS Publications Warehouse

Lewis, Tyler L.; Lindberg, Mark S.; Schmutz, Joel A.; Bertram, M.R.

2014-01-01

Fires are the major natural disturbance in the boreal forest, and their frequency and intensity will likely increase as the climate warms. Terrestrial nutrients released by fires may be transported to boreal lakes, stimulating increased primary productivity, which may radiate through multiple trophic levels. Using a before-after-control-impact (BACI) design, with pre- and postfire data from burned and unburned areas, we examined effects of a natural fire across several trophic levels of boreal lakes, from nutrient and chlorophyll levels, to macroinvertebrates, to waterbirds. Concentrations of total nitrogen and phosphorus were not affected by the fire. Chlorophyll levels were also unaffected, likely reflecting the stable nutrient concentrations. For aquatic invertebrates, we found that densities of three functional feeding groups did not respond to the fire (filterers, gatherers, scrapers), while two groups increased (shredders, predators). Amphipods accounted for 98% of shredder numbers, and we hypothesize that fire-mediated habitat changes may have favored their generalist feeding and habitat ecology. This increase in amphipods may, in turn, have driven increased predator densities, as amphipods were the most numerous invertebrate in our lakes and are commonly taken as prey. Finally, abundance of waterbird young, which feed primarily on aquatic invertebrates, was not affected by the fire. Overall, ecosystems of our study lakes were largely resilient to forest fires, likely due to their high initial nutrient concentrations and small catchment sizes. Moreover, this resilience spanned multiple trophic levels, a significant result for ecologically similar boreal regions, especially given the high potential for increased fires with future climate change.

The impact of fire on the geochemistry of speleothem-forming drip water in a sub-alpine cave.

PubMed

Coleborn, Katie; Baker, Andy; Treble, Pauline C; Andersen, Martin S; Baker, Andrew; Tadros, Carol V; Tozer, Mark; Fairchild, Ian J; Spate, Andy; Meehan, Sophia

2018-06-12

Fire dramatically modifies the surface environment by combusting vegetation and changing soil properties. Despite this well-documented impact on the surface environment, there has been limited research into the impact of fire events on karst, caves and speleothems. Here we report the first experiment designed to investigate the short-term impacts of a prescribed fire on speleothem-forming cave drip water geochemistry. Before and after the fire, water was collected on a bi-monthly basis from 18 drip sites in South Glory Cave, New South Wales, Australia. Two months post-fire, there was an increase in B, Si, Na, Fe and Pb concentrations at all drip sites. We conclude that this response is most likely due to the transport of soluble ash-derived elements from the surface to the cave drip water below. A significant deviation in stable water isotopic composition from the local meteoric water line was also observed at six of the sites. We hypothesise that this was due to partial evaporation of soil water resulting in isotopic enrichment of drip waters. Our results demonstrate that even low-severity prescribed fires can have an impact on speleothem-forming cave drip water geochemistry. These findings are significant because firstly, fires need to be considered when interpreting past climate from speleothem δ 18 O isotope and trace element records, particularly in fire prone regions such as Australia, North America, south west Europe, Russia and China. Secondly, it supports research that demonstrates speleothems could be potential proxy records for past fires. Copyright © 2017 Elsevier B.V. All rights reserved.

Multi-trophic resilience of boreal lake ecosystems to forest fires.

PubMed

Lewis, Tyler L; Lindberg, Mark S; Schmutz, Joel A; Bertram, Mark R

2014-05-01

Fires are the major natural disturbance in the boreal forest, and their frequency and intensity will likely increase as the climate warms. Terrestrial nutrients released by fires may be transported to boreal lakes, stimulating increased primary productivity, which may radiate through multiple trophic levels. Using a before-after-control-impact (BACI) design, with pre- and postfire data from burned and unburned areas, we examined effects of a natural fire across several trophic levels of boreal lakes, from nutrient and chlorophyll levels, to macroinvertebrates, to waterbirds. Concentrations of total nitrogen and phosphorus were not affected by the fire. Chlorophyll a levels were also unaffected, likely reflecting the stable nutrient concentrations. For aquatic invertebrates, we found that densities of three functional feeding groups did not respond to the fire (filterers, gatherers, scrapers), while two groups increased (shredders, predators). Amphipods accounted for 98% of shredder numbers, and we hypothesize that fire-mediated habitat changes may have favored their generalist feeding and habitat ecology. This increase in amphipods may, in turn, have driven increased predator densities, as amphipods were the most numerous invertebrate in our lakes and are commonly taken as prey. Finally, abundance of waterbird young, which feed primarily on aquatic invertebrates, was not affected by the fire. Overall, ecosystems of our study lakes were largely resilient to forest fires, likely due to their high initial nutrient concentrations and small catchment sizes. Moreover, this resilience spanned multiple trophic levels, a significant result for ecologically similar boreal regions, especially given the high potential for increased fires with future climate change.