Showing papers in "International Journal of Wildland Fire in 2001"

Mapping Fire Regimes Across Time and Space: Understanding Coarse and Fine-scale Fire Patterns

Abstract: This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 Maps of fire frequency, severity, size, and pattern are useful for strategically planning fire and natural resource management, assessing risk and ecological conditions, illustrating change in disturbance regimes through time, identifying knowledge gaps, and learning how climate, topography, vegetation, and land use influence fire regimes. We review and compare alternative data sources and approaches for mapping fire regimes at national, regional, and local spatial scales. Fire regimes, defined here as the nature of fires occurring over an extended period of time, are closely related to local site productivity and topography, but climate variability entrains fire regimes at regional to national scales. In response to fire exclusion policies, land use, and invasion of exotic plants over the last century, fire regimes have changed greatly, especially in dry forests, woodlands, and grasslands. Comparing among and within geographic regions, and across time, is a powerful way to understand the factors determining and constraining fire patterns. Assembling spatial databases of fire information using consistent protocols and standards will aid comparison between studies, and speed and strengthen analyses. Combining multiple types of data will increase the power and reliability of interpretations. Testing hypotheses about relationships between fire, climate, vegetation, land use, and topography will help to identify what determines fire regimes at multiple scales.

Mapping wildland fuels for fire management across multiple scales: Integrating remote sensing, GIS, and biophysical modeling

Abstract: Fuel maps are essential for computing spatial fire hazard and risk and simulating fire growth and intensity across a landscape. However, fuel mapping is an extremely difficult and complex process requiring expertise in remotely sensed image classification, fire behavior, fuels modeling, ecology, and geographical information systems (GIS). This paper first presents the challenges of mapping fuels: canopy concealment, fuelbed complexity, fuel type diversity, fuel variability, and fuel model generalization. Then, four approaches to mapping fuels are discussed with examples provided from the literature: (1) field reconnaissance; (2) direct mapping methods; (3) indirect mapping methods; and (4) gradient modeling. A fuel mapping method is proposed that uses current remote sensing and image processing technology. Future fuel mapping needs are also discussed which include better field data and fuel models, accurate GIS reference layers, improved satellite imagery, and comprehensive ecosystem models.

Accuracy assessment and validation of remotely sensed and other spatial information

Abstract: Today, validation or accuracy assessment is an integral component of most mapping projects incorporating remotely sensed data. Other spatial information may not be so stringently evaluated, but at least requires meta-data that documents how the information was generated. This emphasis on data quality was not always the case. In the 1970s only a few brave scientists and researchers dared ask the question, 'How good is this map derived from Landsat MSS imagery?' In the 1980s, the use of the error matrix became a common tool for representing the accuracy of individual map categories. By the 1990s, most maps derived from remotely sensed imagery were required to meet some minimum accuracy standard. A similar progression can be outlined for other spatial information. However, this progression is about 5 years behind the validation of remotely sensed data. This paper presents a series of steps moving towards better assessment and validation of spatial information and asks the reader to evaluate where they are in this series and to move forward.

Characterizing fuels in the 21st century.

Abstract: This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 The ongoing development of sophisticated fire behavior and effects models has demonstrated the need for a comprehensive system of fuel classification that more accurately captures the structural complexity and geographic diversity of fuelbeds. The Fire and Environmental Research Applications Team (FERA) of the USDA Forest Service, Pacific Northwest Research Station, is developing a national system of fuel characteristic classification (FCC). The system is designed to accommodate researchers and managers operating at a variety of scales, and who have access to a variety of kinds of input data. Users can generate fuel characteristics by accessing existing fuelbed descriptions (fuelbed prototypes) using generic information such as cover type or vegetation form. Fuelbed prototypes will provide the best available predictions of the kind, quality and abundance of fuels. Users can accept these default settings or modify some or all of them using more detailed information about vegetation structure and fuel biomass. When the user has completed editing the fuelbed data, the FCC system calculates or infers quantitative fuel characteristics (physical, chemical, and structural properties) and probable fire parameters specific to that fuelbed. Each user-described fuelbed is also assigned to one of approximately 192 stylized fuel characteristic classes.

Fire, climate change, carbon and fuel management in the Canadian boreal forest

Abstract: This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 Fire is the dominant stand-renewing disturbance through much of the Canadian boreal forest, with large high-intensity crown fires being common. From 1 to 3 million ha have burned on average during the past 80 years, with 6 years in the past two decades experiencing more than 4 million ha burned. A large-fire database that maps forest fires greater than 200 ha in area in Canada is being developed to catalogue historical fires. However, analyses using a regional climate model suggest that a changing climate caused by increasing greenhouse gases may alter fire weather, contributing to an increased area burned in the future. Direct carbon emissions from fire (combustion) are estimated to average 27 Tg carbon year–1 for 1959–1999 in Canada. Post-fire decomposition may be of a similar magnitude, and the regenerating forest has a different carbon sink strength. Measurements indicate that there is a net carbon release (source) by the forest immediately after the fire before vegetation is re-established. Daytime downward carbon fluxes over a burned forest take 1–3 decades to recover to those of a mature forest, but the annual carbon balance has not yet been measured. There is a potential positive feedback to global climate change, with anthropogenic greenhouse gases stimulating fire activity through weather changes, with fire releasing more carbon while the regenerating forest is a smaller carbon sink. However, changes in fuel type need to be considered in this scenario since fire spreads more slowly through younger deciduous forests. Proactive fuel management is evaluated as a potential mechanism to reduce area burned. However, it is difficult to envisage that such treatments could be employed successfully at the national scale, at least over the next few decades, because of the large scale of treatments required and ecological issues related to forest fragmentation and biodiversity.

A patch mosaic burning system for conservation areas in southern African savannas

Abstract: Fire-prone savanna ecosystems in southern African conservation areas are managed by prescribed burning in order to conserve biodiversity. A prescribed burning system designed to maximise the benefits of a diverse fire regime in savanna conservation areas is described. The area burnt per year is a function of the grass fuel load, and the number of fires per year is a function of the percentage area burnt. Fires are point-ignited, under a range of fuel and weather conditions, and allowed to burn out by themselves. The seasonal distribution of planned fires over a year is dependent on the number of fires. Early dry season fires (May–June) tend to be small because fuels have not yet fully cured, while late season fires (August–November) are larger. More fires are ignited in the early dry season, with fewer in the late dry season. The seasonality, area burnt, and fire intensity are spatially and temporally varied across a landscape. This should result in the creation of mosaics, which should vary in extent and existence in time. Envelopes for the accumulated percentage to be burnt per month, over the specified fire season, together with upper and lower buffers to the target area are proposed. The system was formalised after 8 years of development and testing in Pilanesberg National Park, South Africa. The spatial heterogeneity of fire patterns increased over the latter years of implementation. This fire management system is recommended for savanna conservation areas of >20 000 ha in size.

Estimating live fine fuels moisture content using meteorologically-based indices

Abstract: Field measurements of moisture content of several fine fuels (shrub vegetation and live foliage) were performed in Central Portugal and in Catalunya (NE Spain) for 1-10 years. Seasonal and interannual variation of live fine fuels of several species in two regions of the Iberian Peninsula are analysed. The species were grouped in three sets according to their relatively high, intermediate or low seasonal variability. Meteorological data from nearby stations were collected in each study area and used in the evaluation of some indicators of fuel moisture that are used in the Canadian Forest Fire Danger Rating System, namely the Drought Code (DC). It was found that in the summer season the slow response of live fine fuel moisture content (LFFMC) to meteorological conditions, namely to precipitation, was well described by the DC. Empirical correlations between LFFMC and DC for each species and site are proposed.

Fire and land management planning and implementation across multiple scales

Abstract: This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 Ecosystem conditions on Federal public lands have changed, particularly within the last 30 years. Wildfires in the west have increased to levels close to or above those estimated for historical conditions, despite increasing efforts and expertise in fire prevention and suppression capability. To reverse these trends, planning for fire and land management policies, budgets, and restoration must address multiple decision levels (national, regional, local, and project) and incorporate an improved understanding of conditions and their linkage across these scales. Three fundamental issues are identified and discussed that relate to traditional types of planning and the associated lack of achievement of multi-scale integrated resource and fire objectives. Various examples of planning that address these three fundamental issues at different scales are compared to traditional types of planning. Outcomes predicted for an example national scale landscape dynamics model are used to illustrate the differences between three different multi-scale management scenarios.

Spatial data for national fire planning and fuel management

Abstract: This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 Spatial data products are most often developed to support resource management decisions. Rarely can the data stand by themselves as spatially-explicit risk assessments. We discuss the technical aspects of true risk assessments, and the contrast between risk assessments and the underlying spatial data that an agency might use to perform one. We then present the development methodology and results from a comprehensive, national effort at creating resource data products that may be useful in agency- or geographically-specific risk assessments. We have produced a suite of spatial data layers, each a continuous coverage for the conterminous United States, to support national-level, programmatic planning efforts for fire and fuel management. This document describes the development of seven data layers: (1) Potential Natural Vegetation Groups; (2) Current Cover Types; (3) Historical Natural Fire Regimes; (4) Current Condition Classes; (5) National Fire Occurrence; (6) Potential Fire Characteristics; and (7) Population Density Groups. This paper documents the methodology used to develop the spatial products. We used a Geographic Information System (GIS) to integrate biophysical and remote sensing products with disturbance and succession processes. We then assigned attributes developed from succession diagrams to combinations of biophysical, current vegetation, and historical fire regime data layers. Regional ecologists, silviculturists, and fire managers developed the succession diagrams, reviewed and refined the data layers, and assigned condition classes. None of these data layers were developed to stand alone as an integrated risk assessment. Technically-robust risk assessments require quantification not only of the probability of an event occurring—wildland fire in this case—but also of the values at risk of damage or loss. The ‘values’ component of a risk assessment is highly dependent on the resource management policies and objectives of the responsible agency. The data presented here were developed for integration by individual agencies into agency-specific plans and risk assessments. For example, planners will use the Current Condition Class data to allocate resources for fire and fuel management. These data are posted on the national, USDA Forest Service website http://fs.fed.us/fire/fuelman.

Pyric properties of some dominant Mediterranean vegetation species

Abstract: The chemical and physical pyric properties of several species, dominant in the Mediterranean Basin, are quantified and compared with each other. Heat content and total and mineral (silica-free) ash content are measured and analysed for 13 species, while surface area-to-volume ratio and particle density are measured for 8 species.

Fire impacts and crowning in the boreal forest: study of a large wildfire in western Quebec

Abstract: Within the context of studying the ecological impacts of wildland fires in the boreal forest, a spatial analysis of a major wildfire was conducted. The fire covered nearly 500 km 2 in the north-western part of Quebec's boreal forest in the summer of 1995. The spatial distribution of different fire impacts on the forest canopy was obtained using timber damage assessment maps. Fire impacts varied throughout the burned area, ranging from areas where trees had completely burned crowns (43%) to remaining patches of trees with green foliage (3%). The effects of local stand and site factors on crown fire, as assessed by the fire impacts, were evaluated using geographic information systems. Despite the large extent and high intensity of the wildfire created by extreme fire weather conditions, stepwise logistic regression and analysis by log-linear models indicated that variations in surface material, stand composition, and estimated stand age played a role in the presence or absence of crowning at the stand level. However, it appears that height and density of stand, as well as topography, did not have a significant influence. Our study presents the variability of fire impacts and its implications, and it provides a better understanding of the relationships between landscape components and fire crowning.

Fire modeling and information system technology

Abstract: This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 Fire modeling and information system technology play an important supporting role in fuel and fire management. Modeling is used to examine alternative fuel treatment options, project potential ecosystem changes, and assess risk to life and property. Models are also used to develop fire prescriptions, conduct prescribed fire operations, and predict fire behavior. Fire models and information systems have greatly influenced fuel assessment methods. As an example, we examine the evolution of technology used to put Rothermel’s fire spread model into application. A review of fire and fuel modeling terminology is given, and the relationship between fire models and fuel models is explained. We review current fire modeling work and the influence that it will have on fuel characterization. Finally, we discuss opportunities and challenges involved in the use of advanced computers, the Internet, Geographic Information Systems (GIS), and remote sensing in fire and fuel management.

Theoretical fire-interval distributions

Abstract: Models for fire interval distributions in ecological communities are proposed, based on an understanding of the processes that influence the probability of fire, especially changes to the amount and condition of the fuel. The models represent changes in the probability of fire as a function of time since last fire. Despite considerable differences in the probability distributions of fire intervals, the models generate very similar age distributions when the mean fire interval is the same. Therefore, fitting the theoretical distributions to observed landscape age structure is unlikely to allow discrimination between different models. Previously, the most commonly used models of fire intervals have been based on the Weibull probability distribution. We believe that this is unnecessarily restrictive, and a broader range of models should be considered. The models may be based on an a priori understanding of the ecosystem being studied. They should assist interpretation of observed or inferred fire interval distributions.

Modeling fire effects

Abstract: This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 Fire effects are modeled for a variety of reasons including: to evaluate risk, to develop treatment prescriptions, to compare management options, and to understand ecosystems. Fire effects modeling may be conducted at a range of temporal and spatial scales. First-order fire effects are those that are the direct result of the combustion process such as plant injury and death, fuel consumption and smoke production. Modeling these effects provides an important cornerstone for models that operate at larger spatial and temporal scales. Detailed physical models of heat transfer and the combustion process under development should provide a vehicle for quantifying fire treatment and predicting fire effects. Second-order fire effects are indirect consequences of fire and other post-fire interactions such as weather. They may take place a few hours to many decades after a fire. Some important second-order fire effects are smoke dispersion, erosion, and vegetation succession. Many approaches have been used to model fire effects including empirical, mechanistic, stochastic, and combinations of all three. Selection of the appropriate model approach and scale depends on the objectives of the modeler, as well as the quality and quantity of available data. This paper is not meant to provide an exhaustive review of fire effects models. Instead, it presents a background in approaches to modeling fire effects to provide managers a basis for selecting and interpreting simulation tools.

Fire history differences in adjacent Jeffrey pine and upper montane forests in the eastern Sierra Nevada

Abstract: Fire history and forest structural characteristics of adjacent Jeffrey pine (Pinus jeffreyi) and upper montane forests was investigated in the eastern Sierra Nevada at the University of California Valentine Natural Reserve. Jeffrey pine forests had lower canopy cover, higher amounts of fine fuels, and higher shrub cover when compared to upper montane forest that were dominated by red fir (Abies magnifica). Fire dates were determined using standard dendrochronolgy techniques from fire-scarred Jeffrey pine, lodgepole pine (Pinus contorta var. murrayana), red f ir, and western white pine (Pinus monticola) trees, snags, stumps, and downed logs. Fires were recorded from 1745 to 1889 and mean fire return intervals were 9 and 24.7 years for the Jeffrey pine and upper montane forest types, respectively. The median fire return interval was 9.0 years for Jeffrey pine and 24.0 years for upper montane forests. Significant differences were found in mean fire intervals and fire history distributions between the two similarly sized fire history plots even though they were only separated by approximately 100 m. This study suggests that fire regimes can vary over very fine spatial scales. Differences in fire regimes are likely due to differences in fuel beds and fire behavior.

Water quality, substratum and biotic responses of five central Idaho (USA) streams during the first year following the Mortar Creek fire

Abstract: The Mortar Creek Fire burned 26 000 ha of mixed-conifer Rocky Mountain forest in July–August 1979. Changes in burn stream conditions were examined relative to reference streams for various ecological factors on two to six occasions, from October 1979 to August 1980. Factors included major ions and nutrients, suspended and benthic particulate matter, periphyton (algae), and macroinvertebrates. Elevated levels of most dissolved chemicals in the burn streams were evident soon after the fire and again during spring runoff. However, there were no major disruptions in the relative composition of cations (and presumably of anions also) in the burn streams during the study. Concentration (mg/L) and load (g/s) of some constituents were higher (e.g. NO 3 -N) and of others (e.g. Ca) were lower in the burn than in the reference streams during spring runoff, depending on whether they were normally under biological or geological control, respectively. Suspended sediment and particulate organic matter generally were higher in burn streams, especially during snow-melt runoff or following heavy rain storms. Benthic organic matter was higher in burn streams and was mainly charcoal, compared to the usual leaf litter found in the reference streams. Fine sediments increased and periphyton decreased in the burn streams. The fire increased the sensitivity of the burn streams to more routine smaller-scale disturbances, such as rainstorms, which had major impacts on the burn streams but not on the reference streams. The macroinvertebrate assemblage showed little direct effect from the fire but was severely altered in composition and abundance by the subsequent runoff, scouring, and channel alteration initiated by spring runoff. The burn streams showed considerable individuality in their response to fire depending on the particular set of conditions to which they were exposed.

A tale of two parks: contemporary fire regimes of Litchfield and Nitmiluk National Parks, monsoonal northern Australia

Abstract: Fires burn vast areas of the monsoonal savannas of northern Australia each year. This paper describes the contemporary fire regimes of two ecologically similar, relatively large national parks (Litchfield—1464 km2; Nitmiluk—2924 km2) in the Top End of the Northern Territory, over 8 and 9 years, respectively. Fire histories for both parks were derived from interpretation of LANDSAT TM imagery, supplemented with NOAA-AVHRR for cloudy periods at the end of the 7-month dry season (c. April–Oct). Data concerning seasonality, extent and frequency of burning were analysed with respect to digital coverages for the park as a whole, landscape units, vegetation types, infrastructure and tenure boundaries. Ground-truth data established that interpreted accuracy overall, for 2 assessment years, ranged between 82 and 91% for both parks. Over 50% of Litchfield and 40% of Nitmiluk was burnt on average over this period, with Litchfield being burnt substantially in the earlier, cooler, and moister, dry season, and Nitmiluk mostly in the parched late dry season, after August. On both parks the current frequency of burning in at least low open woodland / heath habitats is ecologically unsustainable. Both parks are prone to extensive fire incursions. The data support earlier regional assessments that the average fire return interval is around 2 years in at least some areas of northern Australia. Nevertheless, comparison of contemporary fire regimes operating in three major regional national parks shows distinct differences, particularly with respect to the extent and seasonality (hence intensity) of burning in relation to different landscape components. Management implications are considered in discussion.

Estimating fuel response time and predicting fuel moisture content from field data

Abstract: We develop a method for estimating equilibrium moisture content (EMC) and fuel moisture response time, using data collected for Eucalyptus twig litter. The method is based on the governing differential equation for the diffusion of water vapour from the fuel, and on a semi-physical formulation for EMC (Nelson 1984), based on the change in Gibbs free energy, which estimates the EMC as a function of fuel temperature and humidity. We then test the model on data collected in Western Australian mallee shrubland and in Tasmanian buttongrass moorland. This method is more generally applicable than those described by Viney and Catchpole (1991) and Viney (1992). The estimates of EMC and response time are in broad agreement with laboratory-based estimates for similar fuels (Anderson 1990a ; Nelson 1984). The model can be used to predict fuel moisture content by a book-keeping method. The predictions agree wellwith the observations for all three of our data sets.

El Niño and its impact on fire weather conditions in Alaska

Abstract: Examining the relationship of El Nino to weather patterns in Alaska shows wide climate variances that depend on the teleconnection between the tropics and the northern latitudes. However, the weather patterns exhibited in Alaska during and just after moderate to strong El Nino episodes are generally consistent: above normal temperature and precipitation along the Alaskan coast, and above normal temperature and below normal precipitation in the interior, especially through the winter. The warm, dry conditions in the Alaskan interior increase summer wildfire potential. Statistics on the area burned since 1940 show that 15 out of 17 of the biggest fire years occurred during a moderate to strong El Nino episode. These 15 years account for nearly 63% of the total area burned over the last 58 years. Evidence points to increased dry thunderstorms and associated lightning activity during an El Nino episode; the percentage of total area burned by lightning caused fires during five episodes increased from a normal of less than 40% to a high of about 96%.

A statistical classification of Mediterranean species based on their flammability components

Abstract: Eight dominant Mediterranean species were classified into similar groups according to their expected flammability, by applying multivariate statistical methods (Hierarchical Cluster Analysis and Canonical Discriminant Analysis) on the values of their most significant pyric properties (heat content, total and mineral ash content, surface area-to-volume ratio, particle density). Based on the statistical classification, meaningful explanations of the flammability differences among individual species were deduced. The results were in good agreement with similar rankings based on laboratory tests. Further validation may render the method widely applicable for the assessment of species potential flammability without laboratory flammability tests.

Postfire survival in south Florida slash pine: interacting effects of fire intensity, fire season, vegetation, burn size, and bark beetles

Abstract: We used path analysis to examine postfire survival of south Florida slash pine (Pinus elliottii var. densa) at Archbold Biological Station in south-central Florida. We considered the interacting factors of bark beetle infestation, fire intensity (estimated by bark char, percentage of canopy green, and other measures), season of burn, burn size, and vegetation structure and composition. Trees were sampled in 24 burned areas for 3 years after each fire. Fires on recently-burned sites (5–19 years since previous fire) killed fewer trees (44% mortality) than fires on sites > 25 years postfire (71%). For long-unburned sites, we used multiple regression to examine 35 variables and form a path model linking nine variables at four levels. Pine survival was most affected by season of burn; fall burns decreased survival indirectly through increases in fire intensity. Higher mortality was associated with greater char height, larger area burned, more intense attacks by the beetle Platypus, occurrence of hickory scrub or flatwoods vegetation, and complete needle consumption. The final path model explained over 90% of the variation in pine survival. It suggested that beetle effects reflect fire intensity, and detailed many complex interactions. Both preburn and fire intensity data were needed to explain a high amount of variance. Analyses of survival within burns produced similar results, but added some patterns due to vegetation differences within burns and higher survival for larger trees. Fire-induced south Florida slash pine mortality did not spread to trees growing in adjacent, unburned areas. Fire intensity may influence pine densities over the upland landscape in all but the most xeric and hydric sites. Fire management to maximize pine survival is feasible, but management for landscape heterogeneity will tolerate variation in fire intensity and pine survival.

Flame residence times and rates of weight loss of eucalypt forest fuel particles

Abstract: Shape, size, composition and arrangement of fuel particles within a fuel array significantly affect the way in which wildland fires behave. Australian eucalypt forest fire behaviour models characterise fine fuels according to the quantity burnt in the flaming zone, and the upper size limit for fine fuel particles is somewhat arbitrarily set at 6 mm for the McArthur Forest Fire Danger Meter and 10 mm for the Forest Fire Behaviour Tables for Western Australia. Flame residence time and rate of weight loss during combustion of dry eucalypt leaves and different dimensions of round wood were measured to provide a scientific basis for standardising litter fuel sampling in dry eucalypt forests. Eucalypt leaves burnt at a rate equivalent to a piece of 4 mm diameter round wood, with smaller diameter round wood being the most flammable component of the fuel array. Based on flame residence times of individual fuel particles measured in the laboratory, and eucalypt surface fuel arrays observed in the field, fine litter fuel sampling should be standardised to leaves and round wood less than 6 mm in diameter. This study also enables the determination of the contribution of larger fuel particles to flaming zone combustion and intensity.

Benthic macroinvertebrate assemblages in five central Idaho (USA) streams over a 10-year period following disturbance by wildfire

Abstract: The effects of wildfire on benthic macroinvertebrate assemblages of streams in mixed-conifer forest were examined for 10 successive years following the Mortar Creek Fire of 1979. Changes in burned-catchment streams were evaluated relative to a paired set of reference-catchment streams. Taxa richness and total abundance tended to be lower in burn than in reference streams but to converge near the end of the study; increases in the final years in both burn and reference streams were associated with reduced flows due to drought. Total biomass and that of the scraper, filterer, and miner functional groups usually were greater in the burn streams. Lack of a strong relationship of macroinvertebrate metrics with weather conditions showed that factors specific to each stream also were influencing the biotic community. Mean among-year Jaccard similarity was lower for burn than for reference streams. Specific taxa responded differently to the effects of fire. Densities of disturbance-adapted forms (e.g. Chironomidae, Baetis) increased after the fire but not during the drought period of more stable flows at the end of the study; many other taxa showed the opposite response. Adverse effects of wildfire on the biotic community were largely the result of physical changes in habitat due to increased runoff. Timing and magnitude of effects differed widely among streams as a result of differences in stream size, burn severity, and specific storm or snow-melt events. Though major effects of the fire on the macroinvertebrates dissipated within 7 years, adjustment in the habitat and biotic conditions still were taking place at the end of 10 year and normal recovery patterns may have been obscured by the drought.

Occurrence of wildfire in the northern Great Lakes Region: Effects of land cover and land ownership assessed at multiple scales

Abstract: Risk of wildfire has become a major concern for forest managers, particularly where humans live in close proximity to forests. To date, there has been no comprehensive analysis of contemporary wildfire patterns or the influence of landscape-level factors in the northern, largely forested parts of Minnesota, Wisconsin and Michigan, USA. Using electronic archives from the USDA Forest Service and from the Departments of Natural Resources of Minnesota, Wisconsin, and Michigan, we created and analysed a new, spatially explicit data set: the Lake States Fire Database. Most of the 18 514 fires during 1985-1995 were smaller than 4 ha, although there were 746 fires larger than 41 ha. Most fires were caused by debris burning and incendiary activity. There was considerable interannual variability in fire counts; over 80% of fires occurred in March, April, or May. We analysed the relationship of land cover and ownership to fires at two different fire size thresholds across four gridded spatial scales. Fires were more likely on non-forest than within forests; this was also true if considering only fires larger than 41 ha. An area of National or State Forest was less likely to have experienced a fire during the study period than was a forest of equal size outside National or State Forest boundaries. Large fires were less likely in State Forests, although they were neither more nor less likely to have occurred on National Forests. Fire frequency also varied significantly by forest type. All results were extremely consistent across analysis resolutions, indicating robust relationships.

Fire modelling in Tasmanian buttongrass moorlands. III. Dead fuel moisture

Abstract: An experimental program was carried out in Tasmanian buttongrass moorlands to develop fire behaviour prediction models for improving fire management. This paper describes the results of the fuel moisture modelling section of this project. A range of previously developed fuel moisture prediction models are examined and three empirical dead fuel moisture prediction models are developed. McArthur’s grassland fuel moisture model gave equally good predictions as a linear regression model using humidity and dew-point temperature. The regression model was preferred as a prediction model as it is inherently more robust. A prediction model based on hazard sticks was found to have strong seasonal effects which need further investigation before hazard sticks can be used operationally.

Effects of exotic grasses on potential fine fuel loads in the groundcover of south Florida slash pine savannas

Abstract: Invasive exotic grasses have been hypothesized to increase fine fuel loads, thereby increasing the frequency and intensity of fires. Most studies, however, have been conducted in habitats in which natural fires do not occur frequently. We investigated the effects of two invasive grass species, Imperata cylindrica and Neyraudia reynaudiana, on potential fine fuel loads of south Florida slash pine savannas, which naturally experience frequent fires during the lightning season. Total above-ground biomass of fine fuels and litter biomass were greater in areas where exotic grasses were present than in nearby areas not containing these grasses. In addition, less above-ground biomass of native species was present in areas where N. reynaudiana was present. The increases in both potential total fine fuels and litter suggest that exotic grass invasions can change fire characteristics, even in ecosystems where fires occur very frequently.

Changing fuel management strategies - The challenge of meeting new information and analysis needs

Abstract: This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 ‘The earth, born in fire, baptized by lightning since before life"s beginning, has been and is a fire planet’ EV Komarek Attitudes and policies concerning wildland fire, fire use, and fire management have changed greatly since early European settlers arrived in North America Active suppression of wildfires accelerated early in the 20th Century, and areas burned dropped dramatically In recent years, burned areas and cost of fires have begun to increase, in part due to fuel buildups resulting from fire suppression The importance of fire as an ecosystem process is also being increasingly recognized These factors are leading to changes in Federal agency fire and fuels management policies, including increased emphasis on use of prescribed fire and other treatments to reduce fuel loads and fire hazard Changing fire management strategies have highlighted the need for better information and improved risk analysis techniques for setting regional and national priorities, and for monitoring and evaluating the ecological, economic, and social effects and tradeoffs of fuel management treatments and wildfires The US Department of Interior and USDA Forest Service began the Joint Fire Science Program in 1998 to provide a sound scientific basis for implementing and evaluating fuel management activities Development of remote sensing and GIS tools will play a key role in enabling land managers to evaluate hazards, monitor changes, and reduce risks to the environment and the public from wildland fires

The new smoke management

Abstract: This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 The United States Environmental Protection Agency (EPA) will implement new regulations for the management of atmospheric particulate matter 2.5 µm and less in diameter (PM2.5), tropospheric ozone, and regional haze in the next few years. These three air quality issues relate directly to forest and agriculture burning. Fire generates PM2.5 and ozone precursor gases that reduce visibility. Hence, wild and agricultural land managers will be subject to these air quality regulations much as industrial and mobile sources have been for the past 25 years. In addition, these new regulations come at a time when private as well as public land managers throughout the United States are developing plans to increase their application of fire as a management tool. Prescribed fire will remain viable as a tool for land managers with these new regulations but only under a responsible smoke management paradigm. This paradigm will include formal ‘state-approved’ Smoke Management Programs and will require the use of new and ‘approved’ technologies that have been subjected to public and stakeholder scrutiny as regulatory tools. These programs will acknowledge that wildland fire is different from conventional human-caused air pollution sources. They will recognize that the managed use of fire is a superior option to wildfire from public safety and health perspectives. But they will also require greater utilization of non-burning alternatives in all circumstances, especially where fire is used for economic rather than ecological reasons. Through better smoke management and greater use of non-burning alternatives, steadily reduced smoke emissions will likely result.

Fire modelling in Tasmanian buttongrass moorlands. IV. Sustaining versus non-sustaining fires

Abstract: Buttongrass moorlands are widespread in western Tasmania. In these moorlands, the ability to conduct burning without having to rely on hard fuel boundaries (e.g. vegetation which is too wet to burn, water courses, mineral earth breaks and/or roads) would be a major advantage to land managers. Such burning relies on fires self-extinguishing and is normally referred to as unbounded burning. The aim of this project was to model the probability of fires extinguishing using the data from 156 buttongrass moorland fires. The variables used were wind speed, dead fuel moisture and site productivity. The model, derived from a combination of logistic regression and classification tree modelling, predicts that fires will self-extinguish over a wide range of conditions in low productivity moorlands but, in medium productivity moorlands, the conditions within which fires will self-extinguish will be much more restrictive. As a result, the technique of unbounded burning should be widely applicable in low productivity moorlands, but will be of marginal utility in medium productivity moorlands.

Temperature-time curves at the soil surface in maquis summer fires

Abstract: Many summer fires in Valencia are enhanced by the abundance of maquis. Nevertheless, fire field studies on the soil temperature–time curves under summer conditions with controlled amount and structure of fuel are scarce. Experimental summer fires were conducted to analyse the influence of the fuel load and the fuel structure on the soil temperature-time profiles. The increase of fuel load from 2 to 4 kg m–2 increased the net radiant heat per unit area (5691 to 11263 kJ m–2), the total duration of heat (190 to 396 min) and the duration of temperatures greater than 100oC (19.8 to 35.9 min) whereas the peak temperature increased 100oC (from 416oC to 516oC). Variations of fuel height from 1.5 to 0.75 m and bulk density from 2 to 4 kg m–3 respectively, increased net radiant heat per unit area, Hp/a (6510 to 10 444 kJ m–2), ttotal (219 to 375 min), and t>100oC (9.7 to 36. 1 min) whereas Tmax increased 40oC (446 to 486oC). At plot scale, fire intensity and severity will increase with the fuel load. At plant scale, more degradation will occur in the soil patches with higher bulk density, mainly because an increased duration of high temperatures in soil. Fuel amount and structure are then key factors in maquis fires since they will determine the post-fire patchiness of soil conditions and plant recovery.