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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 ...
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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.
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Fires are a common feature of many landscapes, with numerous and complex ecological consequences. In stream ecosystems, fire can strongly influence fluvial geomorphic characteristics and riparian vegetation, which are structural c...
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Fires are a common feature of many landscapes, with numerous and complex ecological consequences. In stream ecosystems, fire can strongly influence fluvial geomorphic characteristics and riparian vegetation, which are structural components of stream riparian ecosystems that contribute to biodiversity and ecosystem function. However, the effects of fire severity on stream-riparian ecosystems in California's Sierra Nevada region (USA) are not well described, yet critical for effectively informing fire management and policy. At 12 stream reaches paired by fire severity (one high-severity burned, one low-severity burned), no significant differences were found in riparian plant community cover and composition or stream geomorphic characteristics 2-15 years following wildfire. In addition, minimal changes in riparian vegetation and stream geomorphic properties were observed in the first summer following the extensive and severe Rim Fire. However, an upstream-to-downstream influence of multiple fire occurrences was observed over the previous 81 years within each catchment on stream geomorphic metrics, including sediment size, embeddedness and channel geometry, at our study reaches. The inconsistent effects of wildfire on stream-riparian vegetation and geomorphic characteristics over space and time may be related to time since fire and precipitation.
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Climate change is likely to result in an increased frequency of extreme fire events, including more large-extent wildfires. The effects of fire extent on post-fire faunal recovery are poorly understood. Effects on invertebrate det...
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Climate change is likely to result in an increased frequency of extreme fire events, including more large-extent wildfires. The effects of fire extent on post-fire faunal recovery are poorly understood. Effects on invertebrate detritivores are of particular interest due to their functional importance in litter breakdown. We asked if distance from fire edge affected the composition and morphological traits of a key group of large invertebrate detritivores: cockroaches (Blattodea) 6years after fire. We used six replicate transects in herb-rich foothill habitat in areas that were severely burnt during the 2009 Black Saturday fires, north-east of Melbourne, Australia. Transects extended from unburnt controls up to 5km into large extent burns. Habitat variables were measured and cockroach abundances were recorded using artificial habitats comprised of stacked egg trays. Cockroach morphological traits were recorded in the laboratory. Multivariate generalized linear models revealed that habitats varied with transect, but not distance into the burn, suggesting recovery of habitat features relevant to cockroaches. Distance from burn did not affect the species richness or abundance of cockroaches, but both richness and abundance increased with bark and litter cover and decreased at lower temperatures. Cockroach assemblage composition responded significantly to distance into burn, transect and habitat variables, although only Platyzosteria similis was negatively associated with distance into the burn. Fourth corner models including traits did not provide greater predictive power than models including only species abundances and environmental variables. Wing presence, which was associated with smaller body size, did not affect site occupancy. Although species traits did not predict cockroach responses, our work shows that distance into a fire, a surrogate for fire extent, continued to be an important determinant of post-fire assemblages 6years after fire. An increase in large-extent fires may reduce the recolonization potential of some cockroach species, potentially limiting their functional importance in litter breakdown.
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This study shows how high-resolution (～15 cm) simultaneous colour and infra-red digital aerial photography can be used to map both fire severity and, particularly, fire extent, in forest in south-eastern Australia. The results sh...
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This study shows how high-resolution (～15 cm) simultaneous colour and infra-red digital aerial photography can be used to map both fire severity and, particularly, fire extent, in forest in south-eastern Australia. The results show that this methodology is capable of detecting and mapping burnt and unburnt edges under unaffected forest canopy (i.e. still green) - that is, revealing the mosaic of burnt and unburnt areas that often result from planned landscape burning under mild weather conditions (i.e. with little of the brownish canopy scorch that results from more intense bushfires). This has important implications for both fuel management and ecology. It can answer the basic questions of fire and biodiversity managers following planned burning 'how much of the planned area burnt, and, within the burnt area, what aspects were burnt, and how hot did they burn?' The analysis of fire extent by aspect showed that about 80% of southern and eastern aspects remained unburnt during broadscale autumn prescribed burning, with many of these moister aspects potentially providing longer unburnt refuges over multiple burn rotations. The fire severity and extent mapping products, produced using the methodology outlined in this study, have the potential to substantially increase the understanding of the ecological and fuel outcomes of landscape-scale autumn prescribed burning.
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Long‐term, ecosystem‐specific fire regime information improves natural community restoration and management by providing a basis for scientifically reasoned fire management prescriptions. Historical fire regimes can be reconstru...
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Long‐term, ecosystem‐specific fire regime information improves natural community restoration and management by providing a basis for scientifically reasoned fire management prescriptions. Historical fire regimes can be reconstructed to sub‐annual resolution using fire‐scarred trees, and while such reconstructions have become increasingly prevalent across the eastern USA , little information regarding how they vary at landscape scale is available. Most studies report fire regime characteristics (i.e., frequency, seasonality) at site‐composite levels, commonly at ≤1?km~(2)spatial resolution. In this study, we analyzed the historical spatial variation of fire regime characteristics over the past four centuries (1620 CE to present) in a red pine/oak landscape (30.75?km~(2)) in north‐central Pennsylvania, USA . Fire event data were reconstructed based on fire scars and locations of 192 living and dead red pines. The spatial and temporal distributions of fire scars revealed a historical fire regime dominated by frequent, dormant season fires most often detected at relatively small spatial extents and by relatively few trees. There was, however, evidence of less frequent, relatively large fires that scarred high percentages of trees. These fire regime characteristics likely resulted in a spatially and temporally transient patchwork of varying vegetation age and structures resulting in a heterogeneous landscape. At the landscape scale, fire frequency changed with human cultures, while fire spatial extent and scarring patterns appeared to be modulated by drought conditions. Results from this study show historical precedence for landscape‐scale burning across a broad range of drought conditions and spatial extents, which should be considered when designing fire‐management and ecosystem restoration objectives.
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Mapping of fire extent and severity across broad landscapes and timeframes using remote sensing approaches is valuable to inform ecological research, biodiversity conservation and fire management. Compiling imagery from various sa...
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Mapping of fire extent and severity across broad landscapes and timeframes using remote sensing approaches is valuable to inform ecological research, biodiversity conservation and fire management. Compiling imagery from various satellite sensors can assist in long-term fire history mapping; however, inherent sensor differences need to be considered. The New South Wales Fire Extent and Severity Mapping (FESM) program uses imagery from Sentinel and Landsat satellites, along with supervised classification algorithms, to produce state-wide fire maps over recent decades. In this study, we compared FESM outputs from Sentinel 2 and Landsat 8 sensors, which have different spatial and spectral resolutions. We undertook independent accuracy assessments of both Sentinel 2 and Landsat 8 sensor algorithms using high-resolution aerial imagery from eight training fires. We also compared the FESM outputs from both sensors across 27 case study fires. We compared the mapped areas of fire severity classes between outputs and assessed the classification agreement at random sampling points. Our independent accuracy assessment demonstrated very similar levels of accuracy for both sensor algorithms. We also found that there was substantial agreement between the outputs from the two sensors. Agreement on the extent of burnt versus unburnt areas was very high, and the severity classification of burnt areas was typically either in agreement between the sensors or in disagreement by only one severity class (e.g., low and moderate severity or high and extreme severity). Differences between outputs are likely partly due to differences in sensor resolution (10 m and 30 m pixel sizes for Sentinel 2 and Landsat 8, respectively) and may be influenced by landscape complexity, such as terrain roughness and foliage cover. Overall, this study supports the combined use of both sensors in remote sensing applications for fire extent and severity mapping.
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In recent years, there have been increasing efforts to understand effects of prescribed fire on population dynamics of wild turkeys (Meleagris gallopavo; turkeys) in pine (Pinusspp.) forests. Although distribution of turkeys is no...
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In recent years, there have been increasing efforts to understand effects of prescribed fire on population dynamics of wild turkeys (Meleagris gallopavo; turkeys) in pine (Pinusspp.) forests. Although distribution of turkeys is not limited to pine forests, these forests provide nesting and brood-rearing habitat throughout the southeastern United States. Previous studies have investigated direct (e.g., nest loss to fire) and indirect (e.g., nest- and brood-site selection) effects of prescribed fire, but little is known about how turkeys are influenced by the spatial scale and shape of prescribed fire. We constructed an individual-based model (IBM) with landscapes of 2 burn unit shapes and 17 spatial scales. We used telemetry data obtained from global positioning system-marked female turkeys to replicate movement behaviors of turkeys within the model. We hypothesized that use of units burned during the current year (<1 yr) would decrease as scale of fires increased, and that shape of burn units would influence use by turkeys. Spatial scale most influenced turkey use; the greatest use was in burned stands of approximately 23 ha in size, whereas least use was associated with burned stands >1,269 ha. At a spatial scale of 23 ha, the daily percent use of rectangular burn units was 7% greater than square-shaped burn units. Likewise, daily percent use of rectangular burn units was 34% greater than square-shaped burn units at a spatial scale of 1,269 ha. When burn units were rectangular-shaped, daily percent use decreased by 48% as the spatial extent of the fires increased from 23 ha to 203 ha. Likewise, when burn units were square-shaped, turkey use decreased by 49% as spatial extent of fires increased from 23 ha to 203 ha. Our findings suggest the importance of managing forested landscapes with prescribed fires not exceeding approximately 200 ha if wild turkeys are a management concern. (c) 2020 The Wildlife Society.
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The purpose of this work is to establish dimensionless correlations for the flame extent under a ceiling that can be used for large-scale calculations of radiative heat fluxes for which numerical simulations may be prohibitive. To...
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The purpose of this work is to establish dimensionless correlations for the flame extent under a ceiling that can be used for large-scale calculations of radiative heat fluxes for which numerical simulations may be prohibitive. Towards this objective, this paper presents a numerical study of the flame height in an open pool fire and the subsequent flame extent under the ceiling. The stoichiometric mixture fraction is used to define the continuous flame height which also coincides with the maximum mean temperature along the centerline of the fire. The size of the pool fire is 0.1 m x 0.1 m having heat release rates (HRRs) from 2 to 100 kW for two ceiling heights of 30 and 50 cm. The predicted free flame height and horizontal flame extent are compared to existing correlations and experimental data in the literature. It is found that the predicted continuous flame height is about three fifths that of the experimental mean flame height reported in the literature. The predicted horizontal flame extent also agrees well with existing experimental correlations, although some difference may indicate that the relation between the mean and continuous flame heights derived for an open free pool fire may no longer apply due to the presence of the ceiling which affects air entrainment and the turbulence of the ceiling flame jet. (C) 2017 Elsevier Ltd. All rights reserved.
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Wildland and wilderness refer to areas of land which have been subject to little or no modification by human activity. These areas are important due to their role as wildlife habitats, the contributions they make to air and water ...
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Wildland and wilderness refer to areas of land which have been subject to little or no modification by human activity. These areas are important due to their role as wildlife habitats, the contributions they make to air and water quality and for human recreation. However, the intermingling of wildland and homes also increases the risk to life and property through wildfires. Management of this risk requires current and detailed knowledge of the spatial extent of wildland. What constitutes wildland vegetation is often difficult to define and may be influenced by both the horizontal continuity and vertical structure. We present a method to map wildland vegetation based on a combination of a vertically stratified cover threshold and spatial morphology. To test its practical application, the method was applied to airborne lidar data collected prior to a major wildfire that occurred in Australia in 2009. Distance between the lidar defined wildland extent and homes impacted by the fire was assessed and compared to previously published data using manual delineation of wildland extent. Results showed that the proportion of homes destroyed at the wildland boundary was greater than reported in previous fires and that there was an exponential decline in the proportion of homes destroyed as a function of distances to wildland. Although the method is objective the extent of wildland depends on the parameters which define thresholds of cover and lateral extent and connectivity. This highlights the need for a clear definition of wildland that can be used to determine extent using objective methods such as those described, whether this is in the context of quantifying wildfire vulnerability or other related applications such as ecological assessment and monitoring.
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Substantial areas of eastern Indonesia are semi-arid (with a pronounced dry season extending from April to November) with extensive areas of uncultivated vegetation dominated by savanna grasslands and woodlands. These are highly f...
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Substantial areas of eastern Indonesia are semi-arid (with a pronounced dry season extending from April to November) with extensive areas of uncultivated vegetation dominated by savanna grasslands and woodlands. These are highly fire-prone, despite high population densities reliant on intensive subsistence agriculture and an official national fire policy that prohibits all burning. To date, no regional studies have been undertaken that reliably assess the seasonal extent and patterning of prescribedburning and wildfire. Focusing on two case studies in east Sumba (7000 km~2) and central Flores (3000 km~2) in the eastern Indonesian province of Nusa Tenggara Timur, the present paper addresses: (1) the efficacy of applying standard remote sensing and geographic information system tools as developed for monitoring fire patterns in savanna landscapes of adjacent northern Australia, for (2) describing the seasonal patterning of burning at village and broader regional scales in 2003 and 2004. Despite recurring cloudiness, which significantly affected daily fire detection of 'hotspots' from Advanced Very High Resolution Radiometer and Moderate Resolution Imaging Spectroradiometer sensors, fire mapping from Landsat imagery was undertaken successfully to reveal: (1) fires burnt an annual average of 29% of eastern Sumba (comprising mostly grassland savanna), and 11% of central Flores (with large forested areas); (2) most fire extent occurred in savanna grassland areas, and significantly also in cultivated lands and small remnant patches of forest; (3) most fire activity occurred under harsh, late dry season conditions; and (4) while the great majority of individual fires were less than 5 ha, some late dry season fires were hundreds of hectares in extent. The potential routine application of different image sensors for fire mapping and hotspot detection is considered in discussion.
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