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In the spring and summer of 2019–2020, the 'Black Summer' bushfires burned more than 97 000 km2 of predominantly Eucalyptus dominated forest habitat in eastern Australia. The Black Summer bushfires prompted great concern that many species had been imperilled by the fires. Here, we investigate the effects that fire severity had on the habitat and abundance of a cool climate lizard Eulamprus tympanum that was identified as a species of concern because 37% of its habitat was burnt in the Black Summer bushfires. We quantified habitat structure and the abundance of E. tympanum at sites which were unburnt, burnt at low severity and at high severity 10, 15 and 23 months after the fires. Our classification of fire severity based on scorch height and canopy status corresponded well with the Australian Government Google Earth Engine Burnt Area Map (AUS GEEBAM) fire severity layer. Ten months after the fires, sites burnt at high severity had less canopy cover, more bare ground and less fine fuel than sites burnt at low severity or unburnt sites. The abundance of E. tympanum varied with survey occasion and was greatest during the warmest sampling period and lowest during the coolest sampling period. The abundance of E. tympanum was consistently lower on sites burnt at high severity than sites burnt at low severity or unburnt sites. Our findings show that higher severity fires had a greater effect on E. tympanum than low severity fires. Our results suggest that E. tympanum were likely to have persisted in burnt sites, with populations in low severity and unburnt sites facilitating population recovery in areas burnt at high severity. Our results also suggest that wildfire impacts on E. tympanum populations will increase because the frequency and extent of severe fires are expected to increase due to climate change. [ABSTRACT FROM AUTHOR]

Context. Sound taxonomy is the cornerstone of biodiversity conservation. Without a fundamental understanding of species delimitations, as well as their distributions and ecological requirements, our ability to conserve them is drastically impeded. Cryptic species -- two or more distinct species currently classified as a single species -- present a significant challenge to biodiversity conservation. How do we assess the conservation status and address potential drivers of extinction if we are unaware of a species' existence? Here, we present a case where the reclassification of a species formerly considered widespread and secure -- the sugar glider (Petaurus breviceps) -- has dramatically increased our understanding of the potential impacts of the catastrophic 2019-20 Australian megafires to this species. Methods. We modelled and mapped the distribution of the former and reclassified sugar glider (Petaurus breviceps). We then compared the proportional overlap of fire severity classes between the former and reclassified distribution, and intersected habitat suitability and fire severity to help identify areas of important habitat following the 2019-20 fires. Key results. Taxonomic revision means that the distribution of this iconic species appears to have been reduced to 8% of its formerly accepted range. Whereas the 2019-20 Australian megafires overlapped with 8% of the formerly accepted range, they overlapped with 33% of the proposed range of the redefined Petaurus breviceps. Conclusions. Our study serves as a sombre example of the substantial risk of underestimating impacts of mega-disturbance on cryptic species, and hence the urgent need for cataloguing Earth's biodiversity in the age of megafire. [ABSTRACT FROM AUTHOR]

Background: 'Megafire' is an emerging concept commonly used to describe fires that are extreme in terms of size, behaviour, and/or impacts, but the term's meaning remains ambiguous. Approach: We sought to resolve ambiguity surrounding the meaning of 'megafire' by conducting a structured review of the use and definition of the term in several languages in the peer‐reviewed scientific literature. We collated definitions and descriptions of megafire and identified criteria frequently invoked to define megafire. We recorded the size and location of megafires and mapped them to reveal global variation in the size of fires described as megafires. Results: We identified 109 studies that define the term 'megafire' or identify a megafire, with the term first appearing in the peer‐reviewed literature in 2005. Seventy‐one (~65%) of these studies attempted to describe or define the term. There was considerable variability in the criteria used to define megafire, although definitions of megafire based on fire size were most common. Megafire size thresholds varied geographically from > 100–100,000 ha, with fires > 10,000 ha the most common size threshold (41%, 18/44 studies). Definitions of megafire were most common from studies led by authors from North America (52%, 37/71). We recorded 137 instances from 84 studies where fires were reported as megafires, the vast majority (94%, 129/137) of which exceed 10,000 ha in size. Megafires occurred in a range of biomes, but were most frequently described in forested biomes (112/137, 82%), and usually described single ignition fires (59% 81/137). Conclusion: As Earth's climate and ecosystems change, it is important that scientists can communicate trends in the occurrence of larger and more extreme fires with clarity. To overcome ambiguity, we suggest a definition of megafire as fires > 10,000 ha arising from single or multiple related ignition events. We introduce two additional terms – gigafire (> 100,000 ha) and terafire (> 1,000,000 ha) – for fires of an even larger scale than megafires. [ABSTRACT FROM AUTHOR]

Mega‐fires of unprecedented size, intensity and socio‐economic impacts have surged globally due to climate change, fire suppression and development. Soil microbiomes are critical for post‐fire plant regeneration and nutrient cycling, yet how mega‐fires impact the soil microbiome remains unclear. We had a serendipitous opportunity to obtain pre‐ and post‐fire soils from the same sampling locations after the 2016 Soberanes mega‐fire burned with high severity throughout several of our established redwood–tanoak plots. This makes our study the first to examine microbial fire response in redwood–tanoak forests. We re‐sampled soils immediately post‐fire from two burned plots and one unburned plot to elucidate the effect of mega‐fire on soil microbiomes. We used Illumina MiSeq sequencing of 16S and ITS1 sequences to determine that bacterial and fungal richness were reduced by 38%–70% in burned plots, with richness unchanged in the unburned plot. Fire altered composition by 27% for bacteria and 24% for fungi, whereas the unburned plots experienced no change in fungal and negligible change in bacterial composition. Pyrophilous taxa that responded positively to fire were phylogenetically conserved, suggesting shared evolutionary traits. For bacteria, fire selected for increased Firmicutes and Actinobacteria. For fungi, fire selected for the Ascomycota classes Pezizomycetes and Eurotiomycetes and for a Basidiomycota class of heat‐resistant Geminibasidiomycete yeasts. We build from Grime's competitor–stress tolerator–ruderal (C‐S‐R) framework and its recent microbial applications to show how our results might fit into a trait‐based conceptual model to help predict generalizable microbial responses to fire. [ABSTRACT FROM AUTHOR]

Deepened knowledge on response of biota and ecological processes following fire is essential for a future with warmer climate and more disturbances. In 2014 the first mega-fire (13,100 ha) for at least a century in Scandinavia hit south-central Sweden, in a production forest landscape shaped by clearcutting forestry. Ecological dynamics is followed in >20 projects from universities, authorities and citizen science initiatives, rapidly accumulating substantial amounts of data. We outline projects and summarize their results during the first four years, demonstrating a rapid succession of fungi, lichens, vascular plants, birds, mammals, ticks, butterflies, beetles, and drastically altered carbon dynamics. We characterize forest operations including regeneration measures and point to patterns in pest and pathogen infestations. 8,000 ha is set aside for natural succession, with the rest harvested and managed for forest production, offering excellent opportunities for studies on salvage logging effects, already evident for birds. We demonstrate a strong regrowth of deciduous trees, and the protected part will in some decades likely develop into the largest deciduous-dominated area in boreal north Europe outside Russia. Continued studies of biodiversity and ecological processes are urgent for this unique area. [ABSTRACT FROM AUTHOR]

Quaking aspen ( Populus tremuloides ) is the most widespread tree species in North America and has supported a unique ecosystem for tens of thousands of years, yet is currently threatened by dramatic loss and possible local extinctions. While multiple factors such as climate change and fire suppression are thought to contribute to aspen’s decline, increased browsing by elk ( Cervus elaphus ), which have experienced dramatic population increases in the last ∼80 years, may severely inhibit aspen growth and regeneration. Fires are known to favor aspen recovery, but in the last several decades the spatial scale and intensity of wildfires has greatly increased, with poorly understood ramifications for aspen growth. Here, focusing on the 2000 Cerro Grande fire in central New Mexico – one of the earliest fires described as a “mega-fire” - we use three methods to examine the impact of elk browsing on aspen regeneration after a mega-fire. First, we use an exclosure experiment to show that aspen growing in the absence of elk were 3× taller than trees growing in the presence of elk. Further, aspen that were both protected from elk and experienced burning were 8.5× taller than unburned trees growing in the presence of elk, suggesting that the combination of release from herbivores and stimulation from fire creates the largest aspen growth rates. Second, using surveys at the landscape level, we found a correlation between elk browsing intensity and aspen height, such that where elk browsing was highest, aspen were shortest. This relationship between elk browsing intensity and aspen height was stronger in burned ( r = −0.53) compared to unburned ( r = −0.24) areas. Third, in conjunction with the landscape-level surveys, we identified possible natural refugia, microsites containing downed logs, shrubs etc. that may inhibit elk browsing by physically blocking aspen from elk or by impeding elk’s ability to move through the forest patch. We did not find any consistent patterns between refuge elements and aspen size or canopy cover suggesting that natural refugia are not aiding in aspen recruitment and that all young aspen were susceptible to browsing. In much of their normal range, aspen are not growing to large size classes, which threatens the future of this iconic species and calls into question the ability of ecosystems to recover from mega-fires. Our results highlight the importance of considering multiple interacting factors (i.e. fire and increased elk browsing) when considering aspen management and regeneration. [ABSTRACT FROM AUTHOR]

Climate change and fire suppression have altered fire regimes globally, leading to larger, more frequent, and more severe wildfires. Responses of coldwater stream biota to single wildfires are well studied, but measured responses to consecutive wildfires in warmwater systems that often include mixed assemblages of native and nonnative taxa are lacking. We quantified changes in physical habitat, resource availability, and biomass of cold- and warmwater oligochaetes, insects, crayfish, fishes, and tadpoles following consecutive megafires (covering >100 km²) in the upper Gila River, New Mexico, USA. We were particularly interested in comparing responses of native and nonnative fishes that might have evolved under different disturbance regimes. Changes in habitat and resource availability were related to cumulative fire effects, fire size, and postfire precipitation. The 2nd of 2 consecutive wildfires in the basin was larger and, coupled with moderate postfire discharge, resulted in increased siltation and decreased algal biomass. Several insect taxa responded to these fires with reduced biomass, whereas oligochaete biomass was unaffected. Biomass of 6 of 7 native fish species decreased after the fires, and decreases were associated with site proximity to fire. Nonnative fish decreases after fire were most pronounced for coldwater salmonids, and warmwater nonnative fishes exhibited limited responses. All crayfish and tadpoles collected were nonnative and were unresponsive to fire disturbance. More pronounced responses of native insects and fishes to fires indicate that increasing fire size and frequency threatens the persistence of native fauna and suggests that management activities promoting ecosystem resilience might help ameliorate wildfire effects. [ABSTRACT FROM AUTHOR]

Landscape-scale wildfire has occurred in higher frequencies across the planet. Fuel reduction treatments to fire-adapted systems have been shown to reduce the impact to human values-at-risk. However, few studies have examined if these treatments contribute to ecosystem resilience, or the capacity of a system to absorb perturbation and return to a similar set of structures or processes. We defined short-term metrics of resiliency to test the hypothesis that fuel reduction treatments in mixed conifer forests increased a fire-adapted system’s resiliency to uncharacteristically severe wildfire. In addition, we tested the hypothesis that fuel reduction treatments reduced burn severity, thereby increasing protection for adjacent human communities. We examined a mixed conifer forested landscape in the southwestern U.S. that was burned by a landscape-scale “mega-fire” in 2011; fuel reduction treatments had been established around communities in the 10 years prior to the fire. Fire effects were highly variable in both treated and untreated forests. However, analysis of resiliency metrics showed that: (a) treated units retained a higher proportion of large trees and had post-fire tree densities within the natural range of variability; (b) the understory herbaceous community had significantly higher cover of native grasses in the treated units, but no significant differences in nonnative cover between treated and untreated units; and (c) high-severity patch sizes were significantly larger in untreated stands and covered a larger proportion of the landscape than historical reference conditions. Fire severity, as defined by overstory mortality and basal area loss, was significantly lower in treated units; on average, trees killed per hectare in untreated units was six times the number of trees killed in treated units. Fuel reduction treatments simultaneously reduced fire severity and enhanced short-term metrics of ecosystem resiliency to uncharacteristically severe fire. [ABSTRACT FROM AUTHOR]

Recent major wildfires may result from a combination of climate change and fuel buildup due to fire exclusion policies of the last century. Are such fires unique to the forests and climate of the 21st century or are they similar to historic fires? Historic fires are recorded primarily by eye witness accounts which seldom contain information needed to examine them with modern fire management tools. The September 1, 1894 fire near Hinckley, Minnesota has well documented accounts from many survivors that allow position of the flame front to be established for a number of times throughout the fire. These accounts allowed us to calibrate a FARSITE model to represent the progression of that fire. FARSITE is a modern fire spread rate simulation model. It requires spatial layers of elevation, slope, aspect, timber type, derived layers of fuel type, canopy cover, stand height, canopy base height, canopy bulk density, duff and coarse woody debris. In this paper we will discuss how we were able to combine present GIS data, historical map data, and present ecosystem properties to provide data needed for these layers. GIS output of FARSITE spread predictions were used to match flame front position to eyewitness accounts and model parameters (primarily, wind speed and direction and fuel model spread rate adjustments) were altered to produce a flame front location and time that matched eyewitness location and timing. [ABSTRACT FROM AUTHOR]

Aim To quantify bird responses to a large unplanned fire, taking into consideration landscape-level fire severity and extent, pre-fire site detection frequency and environmental gradients. Location South-eastern Australia. Methods A major wildfire in 2009 coincided with a long-term study of birds and provided a rare opportunity to quantify bird responses to wildfire. Using hierarchical Bayesian analysis, we modelled bird species richness and the detection frequency of individual species in response to a suite of explanatory variables, including (1) landscape-level fire severity and extent (2) pre-fire detection frequency, (3) site-level vegetation density and (4) environmental variables (e.g. elevation and topography). Results Landscape-level fire severity had strong effects on bird species richness and the detection frequency of the majority of bird species. These effects varied markedly between species; most responded negatively to amount of severely burned forest in the landscape, one negatively to the amount of moderately burned forest and one responded negatively to the total area of burned forest. Only one species - the Flame Robin - responded positively to the amount of burned forest. Relationships with landscape-scale fire extent changed over time for one species - the Brown Thornbill - with initially depressed rates of detection recovering after just 2 years. The majority of species were significantly more likely to be detected in burned areas if they have been recorded there prior to the fire. Main conclusions Birds responded strongly to the severity and spatial extent of fire. They also exhibited strong site fidelity even after severe wildfire which causes profound changes in vegetation cover - a response likely influenced by environmental features such as elevation and topography. [ABSTRACT FROM AUTHOR]

Highlights: [•] Unburnt patches within wildfire boundaries are potential biotic refuges. [•] Within a eucalypt forest wildfire, unburnt patches comprised 1% of the landscape. [•] Most patches arose due to microclimate, but some resulted from prior burning. [•] The refuge quality of a patch is influenced by the mechanism of its occurrence. [•] In variable landscapes potential refuges will occur without management intervention. [ABSTRACT FROM AUTHOR]

Abstract: LANDFIRE is the working name given to the Landscape Fire and Resource Management Planning Tools Project (http://www.landfire.gov). The project was initiated in response to mega-fires and the need for managers to have consistent, wall-to-wall (i.e., all wildlands regardless of agency/ownership), geospatial data, on vegetation, fuels, and terrain to support use of fire behavior and effects prediction systems in guiding policy and management decisions. Base layers were created in a 5-year program of research and development ending in 2009, with processes in place to periodically update fuel and vegetation layers in response to anthropogenic and natural disturbances. LANDFIRE has been institutionalized as the primary data source for modeling activities aimed at meeting the goals of the United States’ National Cohesive Wildland Fire Management Strategy, and the data are available on-line to any user for conducting landscape analyses. Data access and use are high and expected to grow with the increasing scope and complexity of wildland fire management, thus requiring continued LANDFIRE improvements and updates. [Copyright &y& Elsevier]

Abstract: Central Yunnan, China was once dominated by evergreen broad-leaved forests. After a long period of destructive exploitation including agriculture development, overlogging for timber and cutting for fuelwood, these forests are being allowed to reestablish themselves. A large area is now dominated by the conifer Pinus yunnanensis forest which has naturally regenerated and represents an early intermediate stage in the reestablishment of the evergreen broad-leaved forest. In 2006, a mega-fire burned approximately 18.49km2 of this forest. The Pinus is growing back. To examine the process of regeneration dynamics and recovery of the Pinus community after the mega-fire, we investigated plant communities in burned and unburned areas, including a P. yunnanensis shrubland regenerated after the fire, a P. yunnanensis forest without fire occurrence, a P. yunnanensis and Lithocarpus mairei mixed forest, and a Castanopsis orthacantha and Lithocarpus dealbatus evergreen broad-leaved forest, as well as a plantation of P. yunnanensis. Abundant seedlings and saplings of P. yunnanensis and some light-demanding deciduous and evergreen broad-leaved tree species were found in the Pinus shrubland five years after the fire. The frequency distribution by height-classes after the fire was of an inverse-J type, representing very good regeneration. We used space-for-time substitution to obtain an understanding of the directions and pathways of the succession. The approximate successional trend in the area was from the Pinus shrubland to the Pinus forest, then to the mixed coniferous and evergreen broad-leaved Pinus–Lithocarpus forest, then to the evergreen broad-leaved Castanopsis–Lithocarpus forest. In the early successional stage, the floristic richness and species diversity of the Pinus shrubland had lower values as compared to those in the middle and late successional stages, but much higher than those of the Pinus plantation. Our results indicate that the natural recovery of P. yunnanensis after the fire was more efficient than that of a man-made forest of the same species. Nature’s process outpaced human intervention. [Copyright &y& Elsevier]