Potential Fire Behavior Research Articles

Paths of Recovery: Landscape Variability in Forest Structure and Function 25 Years after the 1988 Yellowstone Fires

Understanding succession following severe wildfire is increasingly important for forest managers in western North America and critical for anticipating the resilience of forested landscapes to changing environmental conditions. Successional trajectories set the stage for future carbon storage, abundance and distribution of fuels, and habitat for many species. Early successional forests are increasing throughout the West in response to greater fire activity, but few long-term studies have considered succession following stand-replacing wildfires over large areas. The size and heterogeneity of the 1988 Yellowstone fires created novel opportunities to study succession at an unprecedented scale following severe fire, and we have studied the consequences of these fires for >20 years. In 2012, we began a re-sampling effort in long-term vegetation plots within the area burned by the 1988 fires to answer three overarching questions: (1) Are stand structure and function beginning to converge twenty-five years after the Yellowstone Fires, and what mechanisms may contribute to convergence or divergence? Heterogeneity in forest structure was the rule after the 1988 fires, and postfire lodgepole pine (Pinus contorta var. latifolia) densities ranged from zero to >500,000 trees/ha. The post-1988 cohort of lodgepole pine is reaching a time of critical transitions in structure and function. (2) Are plant community composition and species richness converging or diverging across gradients in local fire severity, post-fire lodgepole pine density, elevation and soil type a quarter-century after the 1988 fires? A central objective in our research has been to understand the relative influence of contingent factors (e.g., local fire severity) vs. deterministic factors (e.g., elevation, soils) on postfire ecosystem development, and how these influences may change through time. (3) How do canopy and surface fuels vary across the postfire landscape, and how will the variation in fuels influence potential fire behavior a quarter century post-fire? Field sampling was conducted for this third question during summer 2012, and data analyses and interpretation are in progress. Overall, results from the proposed study will enhance understanding of succession after one of the most notorious fires of the 20th century. Yellowstone’s postfire forests may serve as benchmarks for forests throughout the region and effective sentinels of change for the Rockies.

Are the applications of wildland fire behaviour models getting ahead of their evaluation again?

Evaluation is a crucial component for model credibility and acceptance by researchers and resource managers. The nature and characteristics of free-burning wildland fires pose challenges to acquiring the kind of quality data necessary for adequate fire behaviour model evaluation. As a result, in some circles it has led to a research culture that tends to avoid evaluating model performance. Operational fire modelling systems commonly used in western North America have been shown to exhibit an underprediction bias when employed to determine the threshold conditions necessary for the onset of crowning and the associated spread rate of active crown fires in conifer forest stands. This pronouncement was made a few years ago after at least a decade of model misapplication in fire and fuel management simulation modelling stemming from a lack of model evaluation. There are signs that the same situation may be repeated with developing physics-based models that simulate potential wildland fire behaviour; these models have as yet undergone limited testing against observations garnered from planned and/or accidental wildland fires. We propose a broad co-operative project encompassing modellers and experimentalists is needed to define and acquire the benchmark fire behaviour data required for model calibration and evaluation.

The effects of bark beetle outbreaks on forest development, fuel loads and potential fire behavior in salvage logged and untreated lodgepole pine forests

Recent mountain pine beetle infestations have resulted in widespread tree mortality and the accumulation of dead woody fuels across the Rocky Mountain region, creating concerns over future forest stand conditions and fire behavior. We quantified how salvage logging influenced tree regeneration and fuel loads relative to nearby, uncut stands for 24 lodgepole pine forests in north-central Colorado that had experienced >70% overstory mortality from mountain pine beetles. We used our field measurements to predict changes in fuel loads and potential fire behavior in the forests that develop over the century following the outbreak and associated harvesting. Our field measurements and stand development projections suggest that salvage logging will alter the potential for canopy fire behavior in future stands by creating conditions that promote regeneration of lodgepole pine and quaking aspen as opposed to subalpine fir. The abundant subalpine fir that has regenerated in untreated, beetle-killed stands is predicted to form a stratum of ladder fuels more likely to allow fires burning on the surface to spread into the forest canopy. Harvesting increased woody surface fuels more than 3-fold compared to untreated stands immediately after treatments; however, coarse fuels will increase substantially (by ∼55Mgha−1) in untreated stands within three decades of the beetle infestation as dead trees topple, and the elevated fuel loads will persist for more than a century. Though salvage logging will treat a small fraction of beetle-infested Colorado forests, in those areas treatment will affect stand development and fuel loads and will alter potential fire behavior for more than a century.

Mapping fire risk in the Model Forest of Urbión (Spain) based on airborne LiDAR measurements

The present study sets a methodological framework to combine LiDAR derived data with fire behaviour models in order to assess fire risk at landscape level for forest management and planning. Two forest areas of the Model Forest in Urbión, Soria (Central Spain) were analyzed, covering 992.7ha and 221.7ha. The modelling phase was based in 160 field sample plots as ground data, and the LiDAR data had a density of first returns of 2pulses/m2, which were used to construct 13 models for stand variables (e.g. basal area, stem volume, branch biomass). The coefficients of determination ranged from 0.167 for shrub cover, to 0.906 for dominant height. The modelled variables were used for a classification of fuel types compatible with the continuous data. The simulation phase was performed using the spatialized data on FlamMap in order to assess the potential fire behaviour resulting across the whole landscape for four scenarios of moisture and wind conditions. The results showed maps of fire intensity and probability of fire occurrence, based on the simulation of 500 random ignition points, which allowed the analysis of the spatial relation between the initial state and allocation of forest resources and their risk of fire. The methodology proposed, as well as the results of this research are directly applicable for operational forest planning at landscape level.

Thirty year change in lodgepole and lodgepole/mixed conifer forest structure following 1980s mountain pine beetle outbreak in western Colorado, USA

Current mortality in lodgepole pine caused by mountain pine beetle (MPB) throughout much of western North America has resulted in concern about future forest structure. To better understand the long-term effects of the current mortality, and how it might differ depending on forest species composition, we measured forest vegetation and woody fuel accumulations in forest affected by a MPB outbreak in the late 1970s and early 1980s and compared conditions to 1980s USDA Forest Service data to quantify changes in the approximately 30years following tree mortality. Stands were classified into two forest type groups based on species composition prior to 1970s/1980s MPB mortality: lodgepole pine and mixed conifer. In the 30years after MPB mortality, lodgepole pine stands’ overstory recovered to 91% of pre-mortality total basal area and 93% of overstory treesha−1. Mixed conifer stands’ basal area and overstory treesha−1 remained significantly reduced. In both forest types relative basal area and treesha−1 of non-pine species increased, and understory treesha−1 increased roughly fivefold. In lodgepole pine stands, the most abundant species in the 1980s understory was subalpine fir, followed by lodgepole pine. By the 2010s, subalpine fir and aspen were the most abundant understory tree species. In mixed conifer stands, subalpine fir and Engelmann spruce dominated all understory size classes in the 1980s and the 2010s. Total down woody fuels were greater in mixed conifer (103Mgha−1) than lodgepole pine stands (60Mgha−1) due to higher rotten fuel accumulation in mixed conifer than lodgepole pine stands. Overall, our results suggest that long-term forest recovery trajectories are dependent on pre-outbreak species composition, though understory densities are likely to increase regardless of non-pine species abundances. These shifts in species and size composition by 30years after outbreak likely have substantial impacts on forest health, potential fire behavior and ecosystem processes. We speculate that forest recovery following the current MPB outbreak in these areas will be similar to observed changes following the 1970s/1980s outbreak.

Spatial modelling of wildland fire danger for risk analysis and conflict resolution in Malaysia: linking Fire Danger Rating Systems (FDRS) with Wildfire Threat Rating Systems (WTRS)

This study provides a comprehensive framework to mitigate or prevent forest and land (or wildland) fire disaster in Malaysia. This system supports emergency response and preparedness for wildland fire by means of integrated modelling, monitoring and mapping of fire danger. In this framework, multi-sensor applications for monitoring fire danger and fire activity are linked with decision-aid models in a Geographic Information System (GIS) environment to generate information required for wildland fire management. Using a customized version of the spatial Fire Management System software, components of the Malaysia Fire Danger Rating System (FDRS) are calculated to provide fire weather, fire behaviour and wildfire threat information. Wildfire threat ratings (WTRs) are assessed on the basis of fire occurrence risk, potential fire behaviour, suppression capability and values at risk. Outputs from the Malaysia FDRS were integrated with hotspots extracted from remote sensing data to generate combined maps of active fire locations, fire danger, potential fire behaviour and uncontrolled wildland fire (or wildfire) threat. In case of wildfire, remotely sensed data were also used to generate wildfire affected area and emergency response maps for emergency management. The system architecture and application models for wildfire analysis, which aid decision-making components for wildfire mitigation and relief, are described. These include early warning of fire, risk analysis, damage assessment and emergency response analysis. This article provides the first documentation of a national, operational system linking fire danger rating with socio-economic values, as defined by the WTR models, to guide fire and rescue decision-making during wildfire events. It is finally shown how the proposed system can reduce the risk offire management disputes in Malaysia by directing the conflict to a more favourable resolution.

Fuel variability following wildfire in forests with mixed severity fire regimes, Cascade Range, USA

Fire severity influences post-burn structure and composition of a forest and the potential for a future fire to burn through the area. The effects of fire on forests with mixed severity fire regimes are difficult to predict and interpret because the quantity, structure, and composition of forest fuels vary considerably. This study examines the relationship between fire severity and post-burn fuel characteristics in forests with mixed severity fire regimes. We sampled live and dead canopy and surface fuels across four fire severity classes on three wildfires that occurred on the east side of the Cascade Range, USA, in 2007 and 2008. We used empirical fuels data and stand structure and composition characteristics to calculate potential surface fire behavior for the four fire severity classes. Post-burn average canopy cover is 25–30% in the low severity class and <10% in the high severity class and ranges from 0 to 50% for all fires. All variables representing post-burn canopy fuels differ by fire severity class. The average loading of dead and down woody fuels <7.6cm diameter and litter is 0.9–1.1kgm−2 in the low severity class and 0.6–0.8kgm−2 in the high severity class. Values for fuel loading variables span a wide range of values within and among fires, and substantial overlap exists among severity classes. Fire severity generally does not influence post-burn dead and down woody fuel loading. Estimates of potential fire behavior also cover wide ranges of values, particularly among fires. Flame lengths average 0.4–0.8m in the low severity classes and 0.3–1.1m in the high severity classes. The range of potential flame length values, modeled with a 16.1kmh−1 midflame wind speed, varies by up to 2.0m within a single severity class (0.6–2.6m). Fire severity does influence potential fire behavior, but typically just one severity class differs from the other three classes. These results indicate that fire severity influences immediate (2–3years) post-burn canopy fuels and potential fire behavior but does not influence dead and down surface fuel loading for the three fires studied. The wide ranges of values for the fuel components analyzed demonstrate the variability that is characteristic of forests with mixed severity fire regimes and emphasize the need to consider the natural heterogeneity of these forests in fire and fuels management. Quantification of post-burn fuel variability is critical for understanding the ecological significance of mixed severity fires and developing restoration strategies that emulate characteristics of the historical fire regime.

Fuel Analysis and Potential Fire Behavior in Mixed Conifer Woodlands of the Great Basin, Nevada, Usa

The Great Basin contains mountain woodlands characterized by a mixture of conifer species (mainly Pinus monophylla, Pinus ponderosa, and Juniperus osteosperma) whose interaction with wildland fire may be affected by climatic changes. To determine expected wildfire behavior at these semiarid mountain sites, we analyzed fuel conditions at Mount Irish and the Clover Mountains, in southeastern Nevada. Current fuels were quantified by herbaceous and shrub vegetation cover, down dead woody debris, litter and duff bulk density, canopy bulk density (CBD), and biomass. At Mount Irish, CBD was about twice that at the Clover Mountains, indicating a potential crown fire behavior of higher severity. On the other hand, continuity of surface fuels, and associated surface fire spread, were greater at the Clover Mountains. To reconstruct canopy fuels at each site, all woody stems on twelve 0.1 ha plots were mapped, measured, and cored. Increment cores were processed using dendrochronological methods; establishment dates and reconstructed DBH were then used as input for simulation models. Canopy fuels and potential fire behavior over time were modeled using the Forest Vegetation Simulator (FVS) and its Fire and Fuels Extension. A transition from surface to crown fire conditions was uncovered at both sites, but at the Clover Mountains it occurred 20-30 years post Euro-American settlement, while at Mount Irish it took place 70-80 years prior to settlement. Because patterns and processes of fuel accumulation and potential fire behavior are not spatially or temporally homogenous in Great Basin mixed-conifer woodlands, conservation targets for these ecosystems cannot simply replicate those designed for either pinyon-juniper vegetation or for ponderosa pine stands in other regions of North America.

Effects of Mountain Pine Beetle on Fuels and Expected Fire Behavior in Lodgepole Pine Forests, Colorado, USA

In Colorado and southern Wyoming, mountain pine beetle (MPB) has affected over 1.6 million ha of predominantly lodgepole pine forests, raising concerns about effects of MPB-caused mortality on subsequent wildfire risk and behavior. Using empirical data we modeled potential fire behavior across a gradient of wind speeds and moisture scenarios in Green stands compared three stages since MPB attack (Red [1–3 yrs], Grey [4–10 yrs], and Old-MPB [∼30 yrs]). MPB killed 50% of the trees and 70% of the basal area in Red and Grey stages. Across moisture scenarios, canopy fuel moisture was one-third lower in Red and Grey stages compared to the Green stage, making active crown fire possible at lower wind speeds and less extreme moisture conditions. More-open canopies and high loads of large surface fuels due to treefall in Grey and Old-MPB stages significantly increased surface fireline intensities, facilitating active crown fire at lower wind speeds (>30–55 km/hr) across all moisture scenarios. Not accounting for low foliar moistures in Red and Grey stages, and large surface fuels in Grey and Old-MPB stages, underestimates the occurrence of active crown fire. Under extreme burning conditions, minimum wind speeds for active crown fire were 25–35 km/hr lower for Red, Grey and Old-MPB stands compared to Green. However, if transition to crown fire occurs (outside the stand, or within the stand via ladder fuels or wind gusts >65 km/hr), active crown fire would be sustained at similar wind speeds, suggesting observed fire behavior may not be qualitatively different among MPB stages under extreme burning conditions. Overall, the risk (probability) of active crown fire appears elevated in MPB-affected stands, but the predominant fire hazard (crown fire) is similar across MPB stages and is characteristic of lodgepole pine forests where extremely dry, gusty weather conditions are key factors in determining fire behavior.

基于FARSITE模型的丰林自然保护区潜在林火行为空间分布特征

Forest fire plays an important role in determining the species composition,age structure,and ecological processes of forest ecosystems.The high forest fuels accumulation coupled with a warmer and drier climate in recent decades makes the study of potential fire behavior of great practical significance.However,most forest fire behavior studies have been conducted at the plot-to-stand levels that cannot meet the landscape-to-regional levels fire management requirements.Researchers and managers are increasingly interested in spatially explicit fire simulation models that can simulate fire spread processes at larger spatial and temporal scales for use in fire management,planning,and scientific analyses.Thus,the main objective of this study was to simulate the potential fire behavior in Fenglin Nature Reserve under the low,moderate and extreme fire danger ratings with a spatially explicit fire behavior simulation model,FARSITE(Fire Area Simulator).According to the fire severity danger standard developed by Rothermel and Rinehart,potential fire behavior zone maps were obtained based on the FARSITE simulation results.Main conclusions from this study were drawn: 1) Under the low fire danger rating,the potential burned areas of classes Ι,Ⅱ,Ⅲ for Fireline intensity were 17765.82 hm2,105.5 hm2,and 1.89 hm2,respectively.The potential burned areas of classes Ι,Ⅱ,and Ⅲ for Flame length were 17722.71 hm2,61.47 hm2,and 0.81 hm2,respectively.under the moderate fire danger rating,the potential burned areas of classes Ι,Ⅱ,Ⅲ for Fireline intensity were 16349.04 hm2,1483.92 hm2,and 6.75 hm2,respectively.The potential burned areas of classes Ι,Ⅱ,and Ⅲ for Flame length were 15785.10 hm2,2033.37 hm2,and 21.24 hm2,respectively.Under the extreme fire danger rating,the potential burned areas of classes Ι,Ⅱ,Ⅲ for Fireline intensity were 7950.78 hm2,7540.38 hm2,and 2351.52 hm2,respectively.The potential burned areas of classes Ι,Ⅱ,and Ⅲ for Flame length were 7108.65 hm2,7263.54 hm2,and 3470.49 hm2,respectively.The results showed that under the low,moderate and extreme high fire danger rating,the potential fire behavior were mainly distributed on the Class Ι and class Ⅱ that can be controlled by persons using hand tools at the head or flanks of fires;2)The spatial distribution characteristic of fire was obvious.The Class Ⅲ were mainly distribution on the mid-eastern region,Class Ⅱ were mainly distribution on the middle region,and Class Ι were widely distribution on the edge of the region;3)The high fire danger areas were distribution of the fuel model FL-Ι and FL-Ⅱ,elevation gradient 300—400 m,slope gradient flat slope and gentle slope.High intensity fire within 500 m road and settlement was much more than that between 1000 and 1500 m;4) The result may give a useful suggestion for fire and fuel management in Fenglin natural reserve.In the future the research should concentrate on validating the simulated results using observed fire behavior in Fenglin Nature Reserve.

Estimation of wildfire size and risk changes due to fuels treatments

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.

Effects of overstory composition and prescribed fire on fuel loading across a heterogeneous managed landscape in the southeastern USA

In the southeastern USA, land use history, forest management and natural geomorphic features have created heterogeneous fuel loads. This apparent temporal and spatial variation in fuel loads make it difficult to reliably assess potential fire behavior from remotely sensed canopy variables to determine risk and to prescribe treatments. We examined this variation by exploring the relationships between overstory forest vegetation attributes, recent fire history, and selected surface fuel components across an 80,000ha contiguous landscape. Measurements of dead and live vegetation components of surface fuels were obtained from 624 permanent plots, or about 1 plot per 100ha of forest cover. Within forest vegetation groups, we modeled the relationship between individual surface fuel components and overstory stand age, basal area, site quality and recent fire history, then stochastically predicted fuel loads across the landscape using the same linkage variables. The fraction of the plot variation, i.e., R2, explained by predictive models for individual fuel components ranged from 0.05 to 0.66 for dead fuels and 0.03 to 0.97 for live fuels in pine dominated vegetation groups. Stand age and basal area were generally more important than recent fire history for predicting fuel loads. Mapped fuel loads using these regressor variables showed a very heterogeneous landscape even at the scale of a few square kilometers. The mapped patterns corresponded to stand based forest management disturbances that are reflected in age, basal area, and fire history. Recent fire history was significant in explaining variation in litter and duff biomass. Stand basal area was positively and consistently related to dead fuel biomass in most groups and was present in many predictive equations. Patterns in live fuel biomass were related to recent fire history, but the patterns were not consistent among forest vegetation groups. Age and basal area were related to live fuels in a complex manner that is likely confounded with periodic disturbances that disrupt stand dynamics. This study complements earlier hazardous fuels research in the southeastern USA, and indicates that succession, disturbance, site quality and decomposition interact with forest management practices to create variable spatial and temporal conditions. The inclusion of additional land use, disturbance history, and soil-topographic variables coupled to improved sampling methods may increase precision and subsequent fuel mapping.

Using fine-scale fuel measurements to assess wildland fuels, potential fire behavior and hazard mitigation treatments in the southeastern USA

The inherent spatial and temporal heterogeneity of fuelbeds in forests of the southeastern United States may require fine scale fuel measurements for providing reliable fire hazard and fuel treatment effectiveness estimates. In a series of five papers, an intensive, fine scale fuel inventory from the Savanna River Site in the southeastern United States is used for building fuelbeds and mapping fire behavior potential, evaluating fuel treatment options for effectiveness, and providing a comparative analysis of landscape modeled fire behavior using three different data sources including the Fuel Characteristic Classification System, LANDFIRE, and the Southern Wildfire Risk Assessment. The research demonstrates that fine scale fuel measurements associated with fuel inventories repeated over time can be used to assess broad scale wildland fire potential and hazard mitigation treatment effectiveness in the southeastern USA and similar fire prone regions. Additional investigations will be needed to modify and improve these processes and capture the true potential of these fine scale data sets for fire and fuel management planning.

Short- and Long-Term Effects on Fuels, Forest Structure, and Wildfire Potential from Prescribed Fire and Resource Benefit Fire in Southwestern Forests, USA

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 fires in ponderosa pine forests, as well as recent resource benefit fires in pinyon-juniper woodlands. The Gila National Forest was the study area because it has a rich history of using fire as a restoration tool. In each vegetation type, fuels and stand structure were sampled using random plots stratified by burn severity in resource benefit fires. In ponderosa pine, sampling and analysis also included prescribed fire and areas subject to repeated resource benefit fires. To assess potential fire behavior, we used the crown fire behavior prediction model Nexus using ninetieth percentile weather conditions. In ponderosa pine forests, surface fuels were similar between prescribed fires and low severity resource benefit fires. However, resource benefit fires significantly reduced basal area, resulting in lower loading of canopy fuels and crown fire potential. Additionally, effects of resource benefit fire on stand structure and fuels seem to be sustained in areas that burned in two or three resource benefit fires in the last century. In pinyon-juniper woodlands, resource benefit low severity fires had no effect on surface or canopy fuel loads. Moderate severity resource benefit fires, on the other hand, did significantly reduce surface and canopy fuel loads. Results from this study are pertinent to fire and fuels managers throughout the southwestern United States who utilize prescribed and resource benefit fire to reduce fuel loads and restore historical forest conditions.

Ecological correlates of fuel dynamics and potential fire behavior in former upland prairie and oak savanna

Fire behavior has changed drastically in North America following Euro-American settlement. We sought to identify potential fire behavior in former prairie and savanna following forest succession, and to predict potential fire behavior from plant community data. We collected data on fuel loads, soils, topography, and plant communities from 239 plots at seven sites in the southern Willamette Valley, Oregon, USA. We defined eight plant cover types; an ordination based on tree species basal area by diameter classes and the cover of ground layer functional types supported these community types. Extant prairie and savanna plots had the lowest fuel loads, but there were no consistent differences in fuels among wooded communities. We used a fire behavior model, BehavePlus, to simulate potential fire behavior in our study plots. Because plant community data, standard fuel models and the ordination axes were poor predictors of fuels and potential fire behavior, we explored a new method of incorporating ecological data into predictions of fire behavior. We used classification and regression trees (CARTs) to find groups of plots that differed in their potential fire behavior. Although the best CART explained only 32% of the variance in potential fire behavior, the CARTs suggest ways to more effectively manage fire behavior – for example, indicating the importance of the legacy effects of savanna trees. Our results suggest that the legacies of succession on historic prairie and savanna have led to novel and heterogeneous fuels complexes, making it difficult to predict potential fire behavior from standard fuel models or community types. CARTs could be useful in other regions, both to indicate locations that should be management priorities and specific management techniques to attenuate fire behavior.

Fuel treatment effectiveness in forests of the upper Atlantic Coastal Plain – An evaluation at two spatial scales

Fuel treatment effectiveness in Southern forests has been demonstrated using fire behavior modeling and observations of reduced wildfire area and tree damage. However, assessments of treatment effectiveness may be improved with a more rigorous accounting of the fuel characteristics. We present two case studies to introduce a relatively new approach to characterizing fuels and predicting potential fire behavior, fuel consumption, and emissions in Southern forests using the Fuel Characteristic Classification System (FCCS) and Consume. The first case study provides fine-scale (<100ha) examples of fuel treatments (prescribed fire, mechanical thinning, mastication, and herbicide treatment) and their potential effect on predicted fire behavior and effects on measured treatment units. The second case study evaluates potential fire behavior across a managed forest landscape (74,000ha) in the upper Atlantic Coastal Plain, South Carolina.Results from the fine-scale assessment indicate that fuel treatments reduce reaction intensity, rate of spread, and flamelength by up to 58%, 57%, and 63%, respectively. Fuel loading of strata that control surface fire behavior (i.e., shrubs, grasses, fine woody fuels, and litter) range from 32.0Mgha−1 in the thinned, untreated unit to 8.5Mgha−1 in the unthinned unit treated with herbicides and prescribed fire. Based on model predictions, up to 80% less fuel would be consumed with concomitant reduction in emissions during a wildfire occurring in the treated units compared to the untreated unit.Assessments of potential fire behavior across the study area indicate that overall hazard is low to moderate for this forested landscape. However, localized areas of high surface fire and crown fire potential were identified. Plot- and stand-based modeling both suggest that the potential for high to extreme fire behavior exists for this landscape. Combined, the two case studies highlight the ability of the FCCS to represent measured fuel characteristics and predict differences in potential fire behavior resulting from fuel treatments. Even small differences in fuel characteristics resulting from fuel treatments or site variation could be detected, allowing the effects of both ecological processes and management actions to be quantified.

Evaluating fuel complexes for fire hazard mitigation planning in the southeastern United States

Fire hazard mitigation planning requires an accurate accounting of fuel complexes to predict potential fire behavior and effects of treatment alternatives. In the southeastern United States, rapid vegetation growth coupled with complex land use history and forest management options requires a dynamic approach to fuel characterization. In this study we assessed potential surface fire behavior with the Fuel Characteristic Classification System (FCCS), a tool which uses inventoried fuelbed inputs to predict fire behavior.Using inventory data from 629 plots established in the upper Atlantic Coastal Plain, South Carolina, we constructed FCCS fuelbeds representing median fuel characteristics by major forest type and age class. With a dry fuel moisture scenario and 6.4kmh−1 midflame wind speed, the FCCS predicted moderate to high potential fire hazard for the majority of the fuelbeds under study. To explore fire hazard under potential future fuel conditions, we developed fuelbeds representing the range of quantitative inventory data for fuelbed components that drive surface fire behavior algorithms and adjusted shrub species composition to represent 30% and 60% relative cover of highly flammable shrub species.Results indicate that the primary drivers of surface fire behavior vary by forest type, age and surface fire behavior rating. Litter tends to be a primary or secondary driver in most forest types. In comparison to other surface fire contributors, reducing shrub loading results in reduced flame lengths most consistently across forest types. FCCS fuelbeds and the results from this project can be used for fire hazard mitigation planning throughout the southern Atlantic Coastal Plain where similar forest types occur. The approach of building simulated fuelbeds across the range of available surface fuel data produces sets of incrementally different fuel characteristics that can be applied to any dynamic forest types in which surface fuel conditions change rapidly.

Potential crown fire behavior in Pinus pinea stands following different fuel treatments

Forest fires are permanent seasonal threats that have been accentuated in recent years by climate change. Taking this problem into consideration, forest policies must propose courses of action to mitigate the effects of fires on ecosystems and their surrounding population. The aim of this study is to evaluate the effectiveness silvicultural treatments of Pinus pinea stands at the polewood stage have on potential fire behavior. Evaluating fire behavior requires a characterization of the fuel at its two levels: surface and crown layers. Given the temporal costs of the latter characterization, field inventory has yielded an equation from which canopy fuel load can be obtained without cutting trees. A complete characterization of the fuel allows for a prediction of fire behavior for each silvicultural treatment and whether or not it will be virulent enough to transfer into crown fire. Polewood stands of P.pinea are susceptible to crown fires because canopy base height is usually overrun by dense and flammable undergrowth. Crown treatments, pruning and crown thinning do not contribute in themselves to eliminating crown fire susceptibility. This study raises the need for joint surface and crown fuel treatments to ensure the effectiveness of extinction efforts. Given current budgetary constraints, fuel treatments are limited to 23.40% of the study area for mitigating possible crown fire impacts on forested area that have a future leading role in the socioeconomic development of surrounding populations.

Evaluating Potential Fire Behavior in Lodgepole Pine-Dominated Forests after a Mountain Pine Beetle Epidemic in North-Central Colorado

Abstract A mountain pine beetle outbreak in Colorado lodgepole pine forests has altered stand and fuel characteristics that affect potential fire behavior. Using the Fire and Fuels Extension to the Forest Vegetation Simulator, potential fire behavior was modeled for uninfested and mountain pine beetle-affected plots 7 years after outbreak initiation and 10 and 80% projected tree fall using measured and projected fuel and stand characteristics. Under 90th percentile weather conditions, uninfested plots exhibited proportionally more crown fire than infested plots. Plots predicted to have crown fire were composed mainly of nonhost conifer species and had a lower and more continuous canopy than infested plots. Where surface fire was predicted to occur, live lodgepole pine was the only conifer present, and plots had significantly lower tree mortality from fire than plots predicted to have crown fire. Mountain pine beetle-induced changes in stand and fuel characteristics resulted in increased intensity of surface fire behavior. Furthermore, with 80% infested tree fall, potential smoke production was predicted to be higher. Tree species composition of stands pre and postbark beetle outbreak is important when identifying mountain pine beetle-caused changes to potential fire behavior.

Development of Customized Fire Behavior Fuel Models for Boreal Forests of Northeastern China

Knowledge of forest fuels and their potential fire behavior across a landscape is essential in fire management. Four customized fire behavior fuel models that differed significantly in fuels characteristics and environmental conditions were identified using hierarchical cluster analysis based on fuels data collected across a boreal forest landscape in northeastern China. Fuel model I represented the dense and heavily branched Pinus pumila shrubland which has significant fine live woody fuels. These forests occur mainly at higher mountain elevations. Fuel model II is applicable to forests dominated by Betula platyphylla and Populus davidiana occurring in native forests on hill slopes or at low mountain elevations. This fuel model was differentiated from other fuel models by higher herbaceous cover and lower fine live woody loading. The primary coniferous forests dominated by Larix gmelini and Pinus sylvestris L. var. mongolica were classified as fuel model III and fuel model IV. Those fuel models differed from one another in average cover and height of understory shrub and herbaceous layers as well as in aspect. The potential fire behavior for each fuel model was simulated with the BehavePlus5.0 fire behavior prediction system. The simulation results indicated that the Pinus pumila shrubland fuels had the most severe fire behavior for the 97th percentile weather condition, and had the least severe fire behavior under 90th percentile weather condition. Fuel model II presented the least severe fire potential across weather conditions. Fuel model IV resulted in greater fire severity than Fuel model III across the two weather scenarios that were examined.