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Fire severity classifications determine fire damage and regeneration potential in post-fire areas for effective implementation of restoration applications. Since fire damage varies according to vegetation and fire characteristics, regional assessment of fire severity is crucial. The objectives of this study were: (1) to test the performance of different satellite imagery and spectral indices, and two field—measured severity indices, CBI (Composite Burn Index) and GeoCBI (Geometrically structured Composite Burn Index) to assess fire severity; (2) to calculate classification thresholds for spectral indices that performed best in the study areas; and (3) to generate fire severity maps that could be used to determine the ecological impact of forest fires. Five large fires in Pinus brutia (Turkish pine) and Pinus nigra subsp. pallasiana var. pallasiana (Anatolian black pine)—dominated forests during 2020 and 2021 were selected as study sites. The results show that GeoCBI provided more reliable estimates of field—measured fire severity than CBI. While Sentinel-2 and Landsat-8/OLI images performed similarly well, MODIS performed poorly. Fire severity classification thresholds were determined for Sentinel-2 based RdNBR, dNBR, dSAVI, dNDVI, and dNDMI and Landsat-8/OLI based dNBR, dNDVI, and dSAVI. Among several spectral indices, the highest accuracy for fire severity classification was found for Sentinel-2 based RdNBR (72.1%) and Landsat-8/OLI based dNBR (69.2%). The results can be used to assess and map fire severity in forest ecosystems similar to those in this study. [ABSTRACT FROM AUTHOR]

Background. Charcoal increases in reflectance with increased intensity and/or duration of heating, and this has been proposed as a potential quantitative metric for fire severity. Because fuel properties also influence reflectance, relationships between heat exposure and reflectance must currently be considered fuel-specific, limiting the application of the method. Aims. We assessed the effect of wood density on charcoal reflectance, to test whether it could be used as a proxy for overall variation in wood properties. Methods. Wood samples from 25 tree species were charred under constant conditions in a microcalorimeter, and reflectance measured by microphotometry. Key results. A positive linear relationship was found between wood density and charcoal reflectance (r = 0.53). Wood density was highly correlated with total heat release per unit volume (r = 0.94). Conclusions. Wood density accounts for a substantial component of the variation in charcoal reflectance under constant heat exposure. Implications. The relationship of density to reflectance shown here is relevant to the assessment of charcoals formed anaerobically, where endogenous heating (combustion of the sample itself) does not occur. In fire-produced chars, an additional increase in reflectance from endogenous heating should produce a stronger correlation, and density might account for a large component of the variation in reflectance under such conditions. [ABSTRACT FROM AUTHOR]

This study explored, for the first time, the drivers shaping large fire size and high severity of forest fires classified as level-2 in Spain, which pose a great danger to the wildland–urban interface. Specifically, we examined how bottom-up (fuel type and topography) and top-down (fire weather) controls shaped level-2 fire behavior through a Random Forest classifier at the regional scale in Galicia (NW Spain). We selected for this purpose 93 level-2 forest fires. The accuracy of the RF fire size and severity classifications was remarkably high (>80%). Fire weather overwhelmed bottom-up controls in controlling the fire size of level-2 forest fires. The likelihood of large level-2 forest fires increased sharply with the fire weather index, but plateaued at values above 40. Fire size strongly responded to minimum relative humidity at values below 30%. The most important variables explaining fire severity in level-2 forest fires were the same as in the fire size, as well as the pre-fire shrubland fraction. The high-fire-severity likelihood of level-2 forest fires increased exponentially for shrubland fractions in the landscape above 50%. Our results suggest that level-2 forest fires will pose an increasing danger to people and their property under predicted scenarios of extreme weather conditions. [ABSTRACT FROM AUTHOR]

Fire activity during 2020 to 2021 in California, USA, was unprecedented in the modern record. More than 19,000 km2 of forest vegetation burned (10× more than the historical average), potentially affecting the habitat of 508 vertebrate species. Of the >9,000 km² that burned at high severity, 89% occurred in large patches that exceeded historical estimates of maximum high-severity patch size. In this 2-y period, 100 vertebrate species experienced fire across >10% of their geographic range, 16 of which were species of conservation concern. These 100 species experienced high-severity fire across 5 to 14% of their ranges, underscoring potentially important changes to habitat structure. Species in this region are not adapted to high-severity megafires. Management actions, such as prescribed fires and mechanical thinning, can curb severe fire behavior and reduce the potential negative impacts of uncharacteristic fires on wildlife. [ABSTRACT FROM AUTHOR]

Copyright of Fire Ecology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

The effect of the North Adrasan, Kumluca wildfire in 2016 on soil element concentrations has been evaluated. Samples were analyzed by neutron activation analysis for As, Ca, Co, Cr, Fe, K, Mg, Mn, Ni, V, and Zn. The main findings of this study were as follows: (1) Co, Cr, Fe, Mg, Mn, Ni, and Zn were higher in burned soils, (2) Cr (up to 9000 mg kg−1) and Ni (up to 3440 mg kg−1) were the elements that increased the most noticeably in burned soils. The results proposed that wildfires could potentially operate as a source of environmental contamination. [ABSTRACT FROM AUTHOR]

Understanding nest site selection is critical to developing effective conservation management actions. The Superb Lyrebird (Menura novaehollandiae) is one of many endemic species extensively impacted by Australia's unprecedented 2019-2020 megafires. Over a period of 5 months, an estimated 43% of the entire range of this slow-breeding species was burnt, with the biggest impact on the central subspecies M. n. novaehollandiae (55%). Four months prior to these megafires, we conducted a field study of nest site habitat selection in the Superb Lyrebird within the Greater Blue Mountains World Heritage Area (15,400 km²): a key stronghold of the central subspecies of the Superb Lyrebird. We found that at the local scale, lyrebird nest sites were more likely to be found in habitats characterized by dense canopy trees and rich in rainforest elements such as vines and treeferns. At the landscape scale, lyrebird nests were most likely to be constructed in rainforest; this firesensitive habitat type made up only 1% of the Greater Blue Mountains World Heritage Area. The probability of nest occurrence also increased with slope. We also found that >74% of all nesting habitat within the Greater Blue Mountains World Heritage Area burned in the 2019-2020 megafires, including 80% of areas of high suitability for nesting. These results suggest that the impact of these megafires on Superb Lyrebirds may be greater than currently thought. Given the importance of rainforest as nesting habitat for the Superb Lyrebird, managers should prioritize its restoration and protect it from future fire events. More broadly, our results illustrate how large-scale catastrophic events-such as megafires-can disproportionately affect habitats critical to specific points within an organism's life cycle. [ABSTRACT FROM AUTHOR]

Fire can alter the trajectory for plant invasions; however, invasive plant responses to fire vary among regions and species. It is unclear how recent increases in large, mixed-severity wildfires in eastern ponderosa pine forests of North America have influenced patterns in plant species invasion. We sampled invasive plant species across three mixed-severity wildfire perimeters over 3666 sample sites in eastern ponderosa pine of western Nebraska, USA. Our analysis sought to determine whether invasive species occurred more frequently and at greater abundance in burned areas, and whether either frequency of occurrence or abundance of invasive plants could be explained by fire severity. We found complex relationships between mixed-severity wildfire and invasive plant species. Cheatgrass (Bromus tectorum) was the most common invasive species sampled, followed by Kentucky bluegrass (Poa pratensis) and smooth brome (Bromus inermis). Cheatgrass and Kentucky bluegrass were more common in burned areas. Cheatgrass occurrence was higher in low and moderate severity burned areas than in unburned locations. While cheatgrass occurred at a similar number of sample sites in unburned and high severity burned areas, cheatgrass cover was lower at high severity burned sites compared to unburned sites. Our results emphasize variation in invasive plant species occurrence and cover in relation to fire in eastern ponderosa pine savannas and the importance of making ecosystem specific decisions regarding invasive species management in response to wildfire. [ABSTRACT FROM AUTHOR]

Abstract: Increases in burned area across the western United States (US) since the mid‐1980s have been widely documented and linked partially to climate factors, yet evaluations of trends in fire severity are lacking. Here we evaluate fire severity trends and their interannual relationships to climate for western US forests from 1985 to 2017. Significant increases in annual area burned at high severity (AABhs) were observed across most ecoregions, with an overall eightfold increase in AABhs across western US forests. The relationships we identified between the annual fire severity metrics and climate, as well as the observed and projected trend toward warmer and drier fire seasons, suggest that climate change will contribute to increased fire severity in future decades where fuels remain abundant. The growing prevalence of high‐severity fire in western US forests has important implications to forest ecosystems, including an increased probability of fire‐catalyzed conversions from forest to alternative vegetation types.

Precise quantification of forest fire impacts is critical for management strategies in support of post-fire mitigation. In this regard, optical remote sensing imagery in combination with spectral unmixing has been widely used to measure fire severity by means of fractional cover of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV), charcoal (CH) and further ground components such as ash, bare soil and rocks. However, most unmixing analyses have made use of a single post-fire image without accounting for the pre-fire state. We aim to assess fire severity from Sentinel-2 data using a bi-temporal spectral unmixing analysis that provides a quantitative fire impact description and is oriented towards the process of change by including pre-fire and post-fire information. Unmixing was based on Random Forest Regression (RFR) modeling using synthetic training data from a bi-temporal spectral library. We describe fire severity as changes associated with the combustion of photosynthetic vegetation (PV–CH fraction) and dieback of photosynthetic vegetation (PV-NPV fraction). Unburned forest was mapped as stable photosynthetic vegetation (PV-PV fraction). We evaluated our approach on a forest fire that burned in a temperate forest region in eastern Germany in 2018. Independent validation was carried out based on reference fractions obtained from very high-resolution (VHR) imagery such as Plante Scope, SPOT6, orthophotos, aerial photos, and Google Earth. The results underline the effectiveness of our unmixing approach, with Root Mean Squared Errors (RMSE) of 0.072 for PV-CH, 0.09 for PV-NPV, and 0.08 for PV-PV fractions. Most of the errors were caused by spectral similarity between charcoal and shadow effects caused by trees, and the coloring of foliage and NPV in the late phenological season of the post-fire Sentinel-2 image. Based on the two-dimensional feature space of PV-CH and PV-NPV fractions, we calculated two metrics to characterize fire impacts: distance, an indicator of disturbance severity (sum of combustion and dieback), and angle, a measure of disturbance composition (gradient between combustion and dieback). Furthermore, we compared the fraction-based metrics with the difference Normalized Burn Ratio (dNBR). Since the dNBR is most sensitive to combustion and presence of charcoal, it does not fully characterize fire-related vegetation loss associated with dieback. The bi-temporal fraction-based indices provide more ecologically meaningful information on fire severity, particularly for regions that are less prone to severe wildfires such as Central Europe.

Context: The mountain pine beetle (MPB; Dendroctonus ponderosae) is a native bark beetle whose outbreaks leads to widespread conifer forest mortality. Of particular concern to forest and wildfire managers is the influence of MPB outbreaks on wildfire via spatial legacies left in impacted forest stands. There is, however, limited consensus in the literature regarding how MPB outbreaks affect wildfire across western North America. Objectives: This meta-analysis aims to (1) summarize available evidence regarding MPB-wildfire interactions, and (2) identify environmental and methodological indicators associated with various wildfire responses (i.e., amplified, neutral, or dampened) post-outbreak. Methods: We include peer-reviewed publications focusing on MPB outbreaks and subsequent wildfire activity in forests across western Canada and the USA between 2000 and 2021. A classification scheme was used to examine attributes of each publication to assess which indicators contribute most to their associated wildfire response. Results: We found that spatial scale, forest fuels, and weather are main drivers of variation in wildfire response post-outbreak. Metrics of forest fuels and inclusion of weather data on a stand-scale are related to amplified fire responses, whereas dampened responses correspond to landscape-scale analyses. Furthermore, red-stage stands are associated with amplified fire response, whereas other stages are associated with dampened response—supporting current conceptual models of the importance of outbreak stage on wildfire. Conclusions: Advancing our understanding regarding drivers of wildfire responses post-MPB outbreak is key to developing accurate, and comparative research studies. These findings provide crucial information for wildfire, and forest management agencies, especially in forests newly exposed to this disturbance interaction under climate change. [ABSTRACT FROM AUTHOR]

Animal ecology and evolution are shaped by environmental perturbations, which are undergoing unprecedented alterations due to climate change. Fire is one such perturbation that causes significant disruption by causing mortality and altering habitats and resources for animals. Fire regimes are changing on a global scale, but the effects of these changes on animal communities are poorly understood. Arthropods are one of the most ubiquitous and diverse animal taxa on the planet and their populations are sensitive to environmental change. Given their wide‐ranging impacts on ecosystem functioning, a better understanding of arthropod responses to changing fire regimes is critical and may also provide more general insights into how other groups might respond to fire.Here, we provide a comprehensive meta‐analytical assessment of how fire influences the arthropod community across habitats and functional groups. Using data from 130 peer‐reviewed papers across the globe, we tested how a variety of fire characteristics, including management regime, severity and time‐since‐fire affect arthropod populations and communities across habitats.Our results show that arthropod communities display substantial variation in response to fire and that community‐level responses are most likely to be detected within the first year. Responses also vary depending on fire characteristics and habitat. Specifically, while community metrics such as diversity were increased by low severity fires, they were reduced by high severity fires. Likewise, evenness increased after prescribed burns but was reduced after wildfire. Measures of arthropod community structure decreased following fires in deserts and forests.Across the entire arthropod community, fire also had variable effects on community diversity. Fire tended to have a negative effect size on arthropods across life stages, but responses did vary among groups. Nearly all functional groups exhibited a negative response to fire with the exception of herbivores, for which abundance, diversity and richness increased after fire.Our results suggest that the increasing prevalence of high‐severity wildfires are changing the structure of arthropod communities. Given their ubiquitous presence and diverse roles in terrestrial ecosystems, these community changes are likely to affect ecosystem functioning in various ways, including through increased herbivory. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Fire is a major cause of tree injury and mortality worldwide, yet our current understanding of fire effects is largely based on ocular estimates of stem charring and foliage discoloration, which are error prone and provide little information on underlying tree function. Accurate quantification of physiological performance is a research and forest management need, given that declining performance could help identify mechanisms of—and serve as an early warning sign for—mortality. Many previous efforts have been hampered by the inability to quantify the heat flux that a tree experiences during a fire, given its highly variable nature in space and time. In this study, we used a dose–response approach to elucidate fire impacts by subjecting Pinus monticola var. minima Lemmon and Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco saplings to surface fires of varying intensity doses and measuring short-term post-fire physiological performance in photosynthetic rate and chlorophyll fluorescence. We also evaluated the ability of spectral reflectance indices to quantify change in physiological performance at the individual tree crown and stand scales. Although physiological performance in both P. monticola and P. menziesii declined with increasing fire intensity, P. monticola maintained a greater photosynthetic rate and higher chlorophyll fluorescence at higher doses, for longer after the fire. Pinus monticola also had complete survival at lower fire intensity doses, whereas P. menziesii had some mortality at all doses, implying higher fire resistance for P. monticola at this life stage. Generally, individual-scale spectral indices were more accurate at quantifying physiological performance than those acquired at the stand-scale. The Photochemical Reflectance Index outperformed other indices at quantifying photosynthesis and chlorophyll fluorescence, highlighting its potential use to quantify crown scale physiological performance. Spectral indices that incorporated near-infrared and shortwave infrared reflectance, such as the Normalized Burn Ratio, were accurate at characterizing stand-scale mortality. The results from this study were included in a conifer cross-comparison using physiology and mortality data from other dose–response studies. The comparison highlights the close evolutionary relationship between fire and species within the Pinus genus, assessed to date, given the high survivorship of Pinus species at lower fire intensities versus other conifers. [ABSTRACT FROM AUTHOR]

Understanding how fire severity affects resprouting plants during post-fire regeneration is key to anticipating Mediterranean vegetation vulnerability in a context of increasingly large fires with high intensity and severity due to climate change. Here, we monitored the water status, leaf gas exchange, and plant growth in holm oaks (Quercus ilex) of central Spain burned with different fire severity throughout the first post-fire year. The Q. ilex burned with high severity (HB+) showed higher water potential and shoot growth than those burned with low severity (LB+) or unburned (B−), especially during spring and summer. In summer, resprouting HB+ and LB+ plants exhibited higher carbon assimilation than unburned ones. Moreover, we also found that plants with higher water availability and growth, i.e., HB+ individuals, had higher specific leaf area and lower water use efficiency. Overall, our study shows that holm oak forests exhibit high plasticity to fire and that Q. ilex burned with high severity have a faster short-term regeneration than those burned with low severity. However, this rapid regeneration is based on a less conservative water-use strategy, which could jeopardize their populations in case of extreme drought events increasingly common in the current context of climate change. [ABSTRACT FROM AUTHOR]

Background. The risk of large, severe bushfires is increasing in Australia, and little is known about their impact on threatened species. Aims. This study aimed to investigated the abundance, occupancy and metapopulation structure of the quokka (Setonix brachyurus) for 5 years following a large, severe bushfire in Western Australia. Methods. Data collected across spatiotemporally replicated transects were used to estimate probabilities of occupancy and abundance, and to evaluate the influence of covariates. Key results. Quokka abundance was reduced to 16% of pre-fire levels, with distances up to 74 km separating subpopulations. Recolonising quokkas occupied habitat in parts of the landscape that had retained some vertical vegetation structure and contained a sedge-dominated understorey, and where damage by feral pigs was low. This coincided with topographic refugia that consisted of deep, mesic riparian systems or perched wetland systems. After 5 years, abundance had increased to 46% of pre-fire levels, with distances of 5-30 km separating subpopulations. Conclusion. Quokka recovery rate is slower than expected, and the metapopulation remains vulnerable to further fragmentation arising from disturbances that affect habitat patch suitability and movement corridors. Implications. Proactive protection of refugia and spatiotemporal habitat connectivity within and surrounding the fire scar is critical for metapopulation recovery. [ABSTRACT FROM AUTHOR]

Abstract Ecological restoration is beneficial to ecological communities in this era of large‐scale landscape change and ecological disruption. However, restoration outcomes are notoriously variable, which makes fine‐scale decision‐making challenging. This is true for restoration efforts that follow large fires, which are increasingly common as the climate changes. Post‐fire restoration efforts, like tree planting and seeding have shown mixed success, though the causes of the variation in restoration outcomes remain unclear. Abiotic factors such as elevation and fire severity, as well as biotic factors, such as residual canopy cover and abundance of competitive understorey grasses, can vary across a burned area and may all influence the success of restoration efforts to re‐establish trees following forest fires. We examined the effect of these factors on the early seedling establishment of a tree species—māmane (Sophora chrysophylla)—in a subtropical montane woodland in Hawaiʻi. Following a human‐caused wildfire, we sowed seeds of māmane as part of a restoration effort. We co‐designed a project to examine māmane seedling establishment. We found that elevation was of overriding importance, structuring total levels of plant establishment, with fewer seedlings establishing at higher elevations. Residual canopy cover was positively correlated with seedling establishment, while cover by invasive, competitive understorey grasses very weakly positively correlated with increased seedling establishment. Our results point to specific factors structuring plant establishment following a large fire and suggest additional targeted restoration actions within this subtropical system. For example, if greater native woody recruitment is a management goal, then actions could include targeted seed placement at lower elevations where establishment is more likely, increased seeding densities at high elevation where recruitment rates are lower, and/or invasive grass removal prior to seeding. Such actions may result in faster native ecosystem recovery, which is a goal of local land managers.

Copyright of Fire Ecology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate and reliable mapping of fire extent and severity is critical for assessing the impact of fire on vegetation and informing post-fire recovery trajectories. Classification approaches that combine pixel-wise and neighbourhood statistics including image texture derived from high-resolution satellite data may improve on current methods of fire severity mapping. Texture is an innate property of all land cover surfaces that is known to vary between fire severity classes, becoming increasingly more homogenous as fire severity increases. In this study, we compared candidate backscatter and reflectance indices derived from Sentinel 1 and Sentinel 2, respectively, together with grey-level-co-occurrence-matrix (GLCM)-derived texture indices using a random forest supervised classification framework. Cross-validation (for which the target fire was excluded in training) and target-trained (for which the target fire was included in training) models were compared to evaluate performance between the models with and without texture indices. The results indicated that the addition of texture indices increased the classification accuracies of severity for both sensor types, with the greatest improvements in the high severity class (23.3%) for the Sentinel 1 and the moderate severity class (17.4%) for the Sentinel 2 target-trained models. The target-trained models consistently outperformed the cross-validation models, especially with regard to Sentinel 1, emphasising the importance of local training data in capturing post-fire variation in different forest types and severity classes. The Sentinel 2 models more accurately estimated fire extent and were improved with the addition of texture indices (3.2%). Optical sensor data yielded better results than C-band synthetic aperture radar (SAR) data with respect to distinguishing fire severity and extent. Successful detection using C-band data was linked to significant structural change in the canopy (i.e., partial-complete canopy consumption) and is more successful over sparse, low-biomass forest. Future research will investigate the sensitivity of longer-wavelength (L-band) SAR regarding fire severity estimation and the potential for an integrated fire-mapping system that incorporates both active and passive remote sensing to detect and monitor changes in vegetation cover and structure. [ABSTRACT FROM AUTHOR]

It is a widespread assumption that burned area and severity are increasing worldwide due to climate change. This issue has motivated former analysis based on satellite imagery, revealing a decreasing trend in global burned areas. However, few studies have addressed burn severity trends, rarely relating them to climate variables, and none of them at the global scale. Within this context, we characterized the spatiotemporal patterns of burned area and severity by biomes and continents and we analyzed their relationships with climate over 17 years. African flooded and non-flooded grasslands and savannas were the most fire-prone biomes on Earth, whereas taiga and tundra exhibited the highest burn severity. Our temporal analysis updated the evidence of a decreasing trend in the global burned area (−1.50% year−1; p < 0.01) and revealed increases in the fraction of burned area affected by high severity (0.95% year−1; p < 0.05). Likewise, the regions with significant increases in mean burn severity, and burned areas at high severity outnumbered those with significant decreases. Among them, increases in severely burned areas in the temperate broadleaf and mixed forests of South America and tropical moist broadleaf forests of Australia were particularly intense. Although the spatial patterns of burned area and severity are clearly driven by climate, we did not find climate warming to increase burned area and burn severity over time, suggesting other factors as the primary drivers of current shifts in fire regimes at the planetary scale. [ABSTRACT FROM AUTHOR]

An analysis of fire characteristics in the boreal forests of Siberia (50–75° N, 60–140° E) was performed for the period 2002–2022. We found a positive trend in the proportion of high-intensity fires in dominant forest stands of Siberia based on long-term series of variations in the Fire Radiative Power (FRP) measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS). Our results showed that there was an increase in the proportion of areas of high-intensity fires over the past decade on about ~30% of the boreal forests of Siberia, including the Arctic zone. For the sample group of fires, the level of correlation (R2 = 0.80–0.94) between the fire impact, classified according to the NBR/dNBR technology, and the integral FRP values was revealed. The intensity of combustion in terms of FRP is associated with the volume of burned biomass and determines the dynamics of specific emissions values per unit area. The results suggest that further increase in fire emissions in Siberia will be determined not only by an increase of burned areas, but also by a redistribution of low- and high-intensity burning and an increase in specific emission values. Finally, we estimated that Siberian fires are responsible for about 5–20% of the total volume of greenhouse gas emissions in the Russian Federation, depending on the fire season scenario. The recurrence of extremely high emissions (296–350 Tg C/year) will make it possible to consider part of Siberian forests as a source of carbon in the nearest future. [ABSTRACT FROM AUTHOR]

Wildfires may facilitate climate tracking of forest species moving upslope or north in latitude. For subalpine tree species, for which higher elevation habitat is limited, accelerated replacement by lower elevation montane tree species following fire may hasten extinction risk. We used a dataset of postfire tree regeneration spanning a broad geographic range to ask whether the fire facilitated upslope movement of montane tree species at the montane‐to‐subalpine ecotone. We sampled tree seedling occurrence in 248 plots across a fire severity gradient (unburned to >90% basal area mortality) and spanning ~500 km of latitude in Mediterranean‐type subalpine forest in California, USA. We used logistic regression to quantify differences in postfire regeneration between resident subalpine species and the seedling‐only range (interpreted as climate‐induced range extension) of montane species. We tested our assumption of increasing climatic suitability for montane species in subalpine forest using the predicted difference in habitat suitability at study plots between 1990 and 2030. We found that postfire regeneration of resident subalpine species was uncorrelated or weakly positively correlated with fire severity. Regeneration of montane species, however, was roughly four times greater in unburned relative to burned subalpine forest. Although our overall results contrast with theoretical predictions of disturbance‐facilitated range shifts, we found opposing postfire regeneration responses for montane species with distinct regeneration niches. Recruitment of shade‐tolerant red fir declined with fire severity and recruitment of shade‐intolerant Jeffrey pine increased with fire severity. Predicted climatic suitability increased by 5% for red fir and 34% for Jeffrey pine. Differing postfire responses in newly climatically available habitats indicate that wildfire disturbance may only facilitate range extensions for species whose preferred regeneration conditions align with increased light and/or other postfire landscape characteristics. [ABSTRACT FROM AUTHOR]

The study aims to explore the added value of the joint use of Sentinel-1 (S1) and Sentinel-2 (S2) data for assessing burn severity in heterogeneous, fragmented ecosystems. The importance of this aim lies in the fact that for both S2 and S1 (as for all the synthetic aperture radar (SAR) C-bands), the impact of fire was found to cause ambiguous effects in complex and fragmented ecosystems. For our investigation, the effectiveness of S1 and S2 fire metrics was first statistically analyzed using ISODATA coupled with field surveys conducted for a fire that occurred on 13 July 2019 in Sardinia. Later, to automatically map burn areas and categorize fire severity, S1 and S2 fire metrics were integrated through a multilevel classification performed at a pixel and feature level. Results were successful (accuracy higher than 94%) compared with independent data sets and in situ investigations. [ABSTRACT FROM AUTHOR]

Tree hollows are an important landscape resource used by fauna for shelter, nesting, and predator avoidance. In fire-prone landscapes, wildfire and climate may impact hollow dynamics; however, assessments of their concurrent impacts are rare. We conducted a field survey at 80 sites in the Sydney Basin bioregion (Australia) to understand how fire frequency, fire severity, mean annual temperature, and mean annual precipitation concurrently impacted the site-density of small- (<5 cm entry width), medium- (5–10 cm entry width) and large-size (>10 cm entry width) tree hollows and tree basal scars (which mediate hollow formation via invertebrate access to heartwood), when tree-size and dead/live status were considered. A unimodal relationship occurred between medium- and large-sized hollow densities and fire frequency and severity, respectively, with hollow densities greatest at intermediate frequencies/severities. Increases of 1.82, 1.43, and 1.17 hollows per site were observed between the 1 (reference) and 2, 2 and 3, and 3 and >3 fire frequency categories. Increases of 1.26, 1.75 and 0.75 hollows per site were observed between the low (reference) and moderate, moderate and high, and high and very high fire severity categories. Fire severity was also positively associated with basal scar density, with increases of 2.52, 8.15, and 8.47 trees per site between the low (reference) and moderate, moderate and high, and high and very high categories. A weak positive and stronger negative association was observed between mean annual temperature and small-sized hollow and basal scar density, respectively. Dead and medium-sized tree density was positively associated with medium-sized hollow and basal scar tree density, respectively. Collectively, our results suggest that wildfires, and in some cases climate, have diverse and size-specific impacts on tree hollow and basal scar density. Our results imply that fire regimes that allow for moderately severe wildfire will promote larger-sized tree hollows, which are a limiting resource for many fauna species. [ABSTRACT FROM AUTHOR]

Collaborative efforts between indigenous peoples and government land managers are gaining recognition as important elements of forest restoration. Unique land allocations, such as the Research Natural Area (RNA) system of the US Forest Service, necessitate novel approaches to achieve desiredoutcomes among stakeholders. We describe a Traditional Ecological Knowledge (TEK) framework that integrates efforts among resource managers, tribal representatives, scientists, and a tribal youth intern program to conduct ecological restoration in a Jeffrey pine (Pinus jeffreyi) forest ecosystemof the western United States with a history of frequent fires. Reintroduction of TEK-based practices provided some moderation of fire effects duringan unplanned wildfire event, benefiting both ecological conditions and a traditional Paiute Indian food source, piagi, the larvae of the Pandora moth (Coloradia pandora). Tribal youth learned about traditional food collection and land management practices, and federal managers discovered thatTEK helped achieve ecological restoration goals. Our collaborative framework increased confidence in the mutual benefits of western science- and TEK-based forest management practices, creating a foundation for long-term partnership in ecosystem restoration.

The combination of direct human influences and the effects of climate change are resulting in altered ecological disturbance regimes, and this is especially the case for wildfires. Many regions that historically experienced low–moderate severity fire regimes are seeing increased area burned at high severity as a result of interactions between high fuel loads and climate warming with a number of negative ecological effects. While ecosystem impacts of altered fire regimes have been examined in the literature, little is known of the effects of changing fire regimes on forest understory plant diversity even though understory taxa comprise the vast majority of forest plant species and play vital roles in overall ecosystem function. We examined understory plant diversity across gradients of wildfire severity in eight large wildfires in yellow pine and mixed conifer temperate forests of the Sierra Nevada, California, USA. We found a generally unimodal hump-shaped relationship between local (alpha) plant diversity and fire severity. High-severity burning resulted in lower local diversity as well as some homogenization of the flora at the regional scale. Fire severity class, post-fire litter cover, and annual precipitation were the best predictors of understory species diversity. Our research suggests that increases in fire severity in systems historically characterized by low and moderate severity fire may lead to plant diversity losses. These findings indicate that global patterns of increasing fire size and severity may have important implications for biodiversity.

Aim: Changes to the extent and severity of wildfires driven by anthropogenic climate change are predicted to have compounding negative consequences for ecological communities. While there is evidence that severe weather events like drought impact amphibian communities, the effects of wildfire on such communities are not well understood. The impact of wildfire on amphibian communities and species is likely to vary, owing to the diversity of their life‐history traits. However, no previous research has identified commonalities among the amphibians at most risk from wildfire, limiting conservation initiatives in the aftermath of severe wildfire. We aimed to investigate the impacts of the unprecedented 2019–2020 black summer bushfires on Australian forest amphibian communities. Location: Eastern coast of New South Wales, Australia. Methods: We conducted visual encounter surveys and passive acoustic monitoring across 411 sites within two regions, one in northeast and one in southeast New South Wales. We used fire severity and extent mapping in two multispecies occupancy models to assess the impacts of fire on 35 forest amphibian species. Results: We demonstrate a negative influence of severe fire extent on metacommunity occupancy and species richness in the south with weaker effects in the north—reflective of the less severe fires that occurred in this region. Both threatened and common species were impacted by severe wildfire extent. Occupancy of burrowing species and rain forest specialists had mostly negative relationships with severe wildfire extent, while arboreal amphibians had neutral relationships. Main Conclusion: Metacommunity monitoring and adaptive conservation strategies are needed to account for common species after severe climatic events. Ecological, morphological and life‐history variation drives the susceptibility of amphibians to wildfires. We document the first evidence of climate change‐driven wildfires impacting temperate forest amphibian communities across a broad geographic area, which raises serious concern for the persistence of amphibians under an increasingly fire‐prone climate. [ABSTRACT FROM AUTHOR]

Spatial and temporal variation in fire characteristics—termed pyrodiversity—are increasingly recognized as important factors that structure wildlife communities in fire‐prone ecosystems, yet there have been few attempts to incorporate pyrodiversity or post‐fire habitat dynamics into predictive models of animal distributions and abundance to support post‐fire management. We use the black‐backed woodpecker—a species associated with burned forests—as a case study to demonstrate a pathway for incorporating pyrodiversity into wildlife habitat assessments for adaptive management. Employing monitoring data (2009–2019) from post‐fire forests in California, we developed three competing occupancy models describing different hypotheses for habitat associations: (1) a static model representing an existing management tool, (2) a temporal model accounting for years since fire, and (3) a temporal–landscape model which additionally incorporates emerging evidence from field studies about the influence of pyrodiversity. Evaluating predictive ability, we found superior support for the temporal–landscape model, which showed a positive relationship between occupancy and pyrodiversity and interactions between habitat associations and years since fire. We incorporated the new temporal–landscape model into an RShiny application to make this decision‐support tool accessible to decision‐makers. [ABSTRACT FROM AUTHOR]

The expansion of subtropical thicket vegetation at the expense of more species-rich, fire-prone fynbos, potentially due to lower frequency and severity of fire and browsing, is a concern in many coastal dune landscapes of the Cape Floristic Region (CFR) where these two vegetation types co-occur. We were interested in the effects of severe fire or browsing treatments (causing complete loss of aboveground biomass) on the vigour of post-fire resprouts of dune thicket shrubs. Cape St Francis, CFR, South Africa. We used an in situ experimental approach to compare the effects of simulated fire and browsing by herbivores on mortality, resprouting vigour and resprouting rate of 10 canopy-forming dune thicket shrub species from different architectural guilds, 5 years after a previous severe wildfire. Survival was significantly lower after fire (85%) than after browsing (95%), and was significantly positively related to pre-treatment shrub size. All measures of resprouting vigour were significantly lower after fire than after browsing, and were significantly positively related to pre-treatment size. Resprouting rate was significantly lower after fire than after browsing, and was significantly positively affected by pre-treatment size. Survival and measures of resprouting vigour were generally decoupled from architectural guild and species identity. Dune thicket shrubs showed high survival after both fire and browsing treatments, suggesting that these species are resilient to frequent complete loss of above-ground biomass. Our results suggest that short interval fires (5–15 years) of high severity will merely maintain the co-occurrence of dune fynbos and thicket vegetation by setting back thicket growth rather than causing large-scale mortality of thicket shrubs. [ABSTRACT FROM AUTHOR]

Background. Wildfire spread is influenced significantly by the weather variability. Wind speed and direction changes, resulting from synoptic weather systems and small-scale meteorological processes in complex terrain, can drastically alter fire intensity and spread. Aims. To investigate the use of vector wind change (VWC) integrated with the Fire Weather Index (FWI) as a new metric in fire danger. Methods. A 20-year FWI and modified FWI was calculated from weather station and gridded numerical weather simulation data. Key results. High VWC is found primarily on the South Island, inland and in areas of complex terrain. After incorporating VWC into the FWI, data from the modified FWI show spatiotemporal patterns that highlight the impact of wind variability in the fire danger. Conclusions. High VWC station data mapped with synoptic type suggest the primary factor in determining high VWC is meso- and micro-scale terrain-driven meteorology, not larger synoptic regimes. Implications. The current fire danger metric, the Fire Weather Index (FWI), does not include wind direction changes for high wind speeds. Therefore, the inclusion of VWC as an additional metric in fire danger calculations in a modified FWI could increase operational understanding of high-danger locations and terrain impacts on extreme and unpredictable fire behaviour. [ABSTRACT FROM AUTHOR]

Copyright of Fire Ecology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wildfire is a critical ecological disturbance in terrestrial ecosystems. Australia, in particular, has experienced increasingly large and severe wildfires over the past two decades while globally fire risk is expected to increase significantly due to the projected increase in fire weather severity and drought condition. Therefore, understanding and predicting fire severity is critical for evaluating current and future impacts of wildfires on ecosystems. Here, we firstly introduce a vegetation16 type specific fire severity classification applied on satellite imagery, which is further used to predict fire severity using antecedent drought conditions, fire weather, and topography of the fire season. Based on a 'leave-one-out' cross-validation experiment, we demonstrate high accuracy for both the fire severity classification and the regression using a suite of performance metrics: determination coefficient (R²), mean absolute error (MPE) and root mean square error (RMSE), which are 0.89, 0.05, and 0.07, respectively. Our results also show that the fire severity prediction results using the vegetation-type specific thresholds could better capture the spatial patterns of fire severity, and has the potential to be applicable for seasonal fire severity forecasting due to the availability of seasonal forecasts of the predictor variables. [ABSTRACT FROM AUTHOR]

The effectiveness of mulching in reducing the risk of erosion has been evaluated in numerous studies. However, its effect on carbon loss has received less attention, despite the potentially negative effects on ecosystem recovery. In this study, the effects of straw helimulching on soil erosion and carbon loss in sediments were investigated after a severe wildfire in NW Spain during the first three years after fire. During the first year after the fire, the accumulated mean sediment yield was 12.4 Mg ha−1 in the control plots and 0.5 Mg ha−1 in the mulched plots. Soil erosion decreased sharply during the second year after the fire and was almost inexistent during the third year after the fire. No differences in carbon concentration were detected between treatments during the period of study. A significantly lower amount of carbon was lost after the mulching treatment due to its effectiveness in reducing sediment erosion. The mulching treatment did not significantly influence the amount of carbon sequestered in the vegetation. Although the application of mulch did not affect carbon fixation in vegetation, its application after fire can be considered a sustainable way of managing forest ecosystems to reduce the impact of fire on carbon emissions. [ABSTRACT FROM AUTHOR]

Forest fires are one of the most severe natural disasters facing global ecosystems, as they have a significant impact on ecological security and social development. As remote sensing technology has developed, burned areas can now be quickly extracted to support fire monitoring and post-disaster recovery. This study focused on monitoring forest fires that occurred in Chongqing, China, in August 2022. The burned area was identified using various satellite images, including Sentinel-2, Landsat8, Environmental Mitigation II A (HJ2A), and Gaofen-6 (GF-6). The burned area was extracted using visual interpretation, differenced Normalized Difference Vegetation Index (dNDVI), and differenced Normalized Burnup Ratio (dNBR). The results showed that: (1) The results of the three monitoring methods were very consistent, with a coefficient of determination R2 > 0.96. (2) A threshold method based on the dNBR-extracted burned area was used to analyze fire severity, with moderate-severity fires making up the majority (58.05%) of the fires. (3) Different topographic factors had some influence on the severity of the forest fires. High elevation, steep slopes and the northwestern aspect had the largest percentage of burned area. [ABSTRACT FROM AUTHOR]

Changes in fire regime of boreal forests in response to climate warming are expected to impact postfire recovery. However, quantitative data on how managed forests sustain and recover from recent fire disturbance are limited.Two years after a large wildfire in managed even‐aged boreal forests in Sweden, we investigated how recovery of aboveground and belowground communities, that is, understory vegetation and soil microbial and faunal communities, responded to variation in the severity of soil (i.e., consumption of soil organic matter) and canopy fires (i.e., tree mortality).While fire overall enhanced diversity of understory vegetation through colonization of fire adapted plant species, it reduced the abundance and diversity of soil biota. We observed contrasting effects of tree‐ and soil‐related fire severity on survival and recovery of understory vegetation and soil biological communities. Severe fires that killed overstory Pinus sylvestris promoted a successional stage dominated by the mosses Ceratodon purpureus and Polytrichum juniperinum, but reduced regeneration of tree seedlings and disfavored the ericaceous dwarf‐shrub Vaccinium vitis‐idaea and the grass Deschampsia flexuosa. Moreover, high tree mortality from fire reduced fungal biomass and changed fungal community composition, in particular that of ectomycorrhizal fungi, and reduced the fungivorous soil Oribatida. In contrast, soil‐related fire severity had little impact on vegetation composition, fungal communities, and soil animals. Bacterial communities responded to both tree‐ and soil‐related fire severity.Synthesis: Our results 2 years postfire suggest that a change in fire regime from a historically low‐severity ground fire regime, with fires that mainly burns into the soil organic layer, to a stand‐replacing fire regime with a high degree of tree mortality, as may be expected with climate change, is likely to impact the short‐term recovery of stand structure and above‐ and belowground species composition of even‐aged P. sylvestris boreal forests. [ABSTRACT FROM AUTHOR]

Copyright of Fire Ecology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Composite Burn Index (CBI) is commonly linked to remotely sensed data to understand spatial and temporal patterns of burn severity. However, a comprehensive understanding of the tradeoffs between different methods used to model CBI with remotely sensed data is lacking. To help understand the current state of the science, provide a blueprint towards conducting broad-scale meta-analyses, and identify key decision points and potential rationale, we conducted a review of studies that linked remotely sensed data to continuous estimates of burn severity measured with the CBI and related methods. We provide a roadmap of the different methodologies applied and examine potential rationales used to justify them. Our findings largely reflect methods applied in North America – particularly in the western USA – due to the high number of studies in that region. We find the use of different methods across studies introduces variations that make it difficult to compare outcomes. Additionally, the existing suite of comparative studies focuses on one or few of many possible sources of uncertainty. Thus, compounding error and propagation throughout the many decisions made during analysis is not well understood. Finally, we suggest a broad set of methodological information and key rationales for decision-making that could facilitate future reviews. This review paper summarises methodologies used to link field-based measures of severity, based on the Composite Burn Index (CBI), with remotely sensed data from optical sensors. It presents key analytical decisions and research gaps in the existing literature. [ABSTRACT FROM AUTHOR]

Burned area and proportion of high severity fire have been increasing in the western USA, and reducing wildfire severity with fuel treatments or other means is key for maintaining fire-prone dry forests and avoiding fire-catalyzed forest loss. Despite the unprecedented scope of firefighting operations in recent years, their contribution to patterns of wildfire severity is rarely quantified. Here we investigate how wildland fire suppression operations and past fire severity interacted to affect severity patterns of the northern third of the 374 000 ha Dixie Fire, the largest single fire in California history. We developed a map of the intensity and type of suppression operations and a statistical model of the Composite Burn Index (CBI) including weather, fuels, and terrain variables during the fire to quantify the importance of operations and prior fires on wildfire severity. Wildfire severity was estimated without operations and previous fires and then compared with modeled severity under observed conditions. Previous low and moderate-severity fire without operations decreased CBI by 38% and 19% respectively. Heavy operations and offensive firing in the footprint of past fires lowered fire severity even more compared to prior fire alone. Medium operations and defensive firing reduced but did not eliminate the moderating effects of past fires. This analysis demonstrates important interactions between suppression operations and previous burns that drive patterns of fire severity and vegetation dynamics in post-fire landscapes. Given the need to reduce wildfire severity to maintain forest resilience, particularly with a warming climate, increased attention to using operations and severity patterns of previous fires known to reduce wildfire severity in megafires are likely to increase forest resilience and improve ecological outcomes.

Abstract Fire severity is a key driver shaping the ecological structure and function of North American boreal ecosystems, a biome dominated by large, high‐intensity wildfires. Satellite‐derived burn severity maps have been an important tool in these remote landscapes for both fire and resource management. The conventional methodology to produce satellite‐inferred fire severity maps generally involves comparing imagery from 1 year before and 1 year after a fire, yet environmental conditions unique to the boreal have limited the accuracy of resulting products. We introduce an alternative method – the ‘hybrid composite’ – based on deriving mean severity over time on a per‐pixel basis within the cloud‐computing environment of Google Earth Engine. It constructs the post‐fire image from satellite data composited from all valid images (i.e., clear‐sky and snow‐free) acquired in the time period immediately after fire through the early growing season of the following year. We compare this approach to paired‐scene and composite approaches where the post‐fire time period is from the growing season 1 year after fire. Validation statistics based on field‐derived data for 52 fires across Alaska and Canada indicate that the hybrid composite method outperforms the other approaches. This approach presents an efficient and cost‐effective means to monitor and explore trends and patterns across broad spatial domains, and could be applied to fires in other regions, especially those with frequent cloud cover or rapid vegetation recovery.

A nine-year time series of nutrient cation and anion concentration and efflux from three forested catchments in the Jemez River Basin Critical Zone Observatory (JRB-CZO) in northern New Mexico was used to quantify the pulse of chemical denudation resulting from varying levels stand-replacing wildfire intensity in May-June of 2013. The 3 years of pre-fire and 6 years of postfire data were also probed to shed light on the mechanisms underlying the pulsed release and the subsequent recovery. The initial large solute pulse released to the streams—K+, Ca2+, Mg2+, SO42-, Cl−, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and total dissolved nitrogen (TDN)—was caused by leaching of hillslope ash deposits during the first monsoon storms post-fire. Debris flow following the wildfire likely redistributed much of the ash-containing sediments along streams and valley bottoms. Sustained elevated solute concentrations observed in the surface waters throughout the post-fire period relative to pre-fire baselines is consistent with these soluble materials being periodically flushed from the soils during wet seasons, i.e., snowmelt and summer monsoons. As microbial mediated reactions and biotic uptake—due to plant regrowth—recover after fire, nutrient ion export (e.g., NO3-, Cl− and SO42-) steadily decreased toward the end of the post fire period, but remained above pre-fire levels, particularly for NO3- and SO42-. Surface water concentrations of polyvalent cations (e.g., Al and Fe) decreased significantly after the fire. Our observations suggest that changes in organic matter composition after fire (e.g., increased humification index—HIX) and the presence of pyrogenic carbon may not favor organo-metal complexation and transport. Finally, differences in burn severity among the three watersheds presented in this study, provide insights of the relative impact of solute exports and resilience. The catchments that experienced high burn severity exhibited greater solute fluxes than the less severely burn. Moreover, despite these differences, toward the end of the post-fire period these surface waters presented low and similar solute effluxes, indicating system recovery. Nonetheless, magnitudes and rebounds were solute and process specific. The results of this study highlight the importance of surface and near surface physical and biogeochemical processes on the long-lasting geochemical denudation of forested catchments following wildfires of varying intensities.

In 2020 the Beachie Creek Fire burned a large, forested area in the northern Oregon Cascade Range that included public and private land and much of the Opal Creek Wilderness. We compiled a pre-fire baseline data set from various sources of the lichens and allied fungi known to occur before the fire within the fire perimeter. These data are presented as an annotated species list documenting two hundred and eighty-three species. Euopsis pulvinata, Lepraria elobata, Miriquidica instrata, Plectocarpon nephromeum, Porpidia flavicunda, and Rhizocarpon distinctum are reported as new for Oregon based on an online search of herbarium records and relevant literature. Near the wilderness area, where populations of listed rare species are known, their occurrences are mapped against a fire severity gradient. Drone-generated images of selected locations before and after the fire are included to help gauge the fire effects on lichen communities. Increased fire activity in the area is potentially causing landscape-level changes in biodiversity, and the data we present represent a historical baseline for future analyses of the effects of the Beachie Creek fire on lichen diversity. [ABSTRACT FROM AUTHOR]

Fire severity mapping can capture heterogeneous fire severity patterns over large spatial extents. Although numerous remote sensing approaches have been established, regional-scale fire severity mapping at fine spatial scales (<5 m) from high-resolution satellite images is challenging. The fire severity of a vast forest fire that occurred in Southwest China was mapped at 2 m spatial resolution by random forest models using Sentinel 2 and GF series remote sensing images. This study demonstrated that using the combination of Sentinel 2 and GF series satellite images showed some improvement (from 85% to 91%) in global classification accuracy compared to using only Sentinel 2 images. The classification accuracy of unburnt, moderate, and high severity classes was significantly higher (>85%) than the accuracy of low severity classes in both cases. Adding high-resolution GF series images to the training dataset reduced the probability of low severity being under-predicted and improved the accuracy of the low severity class from 54.55% to 72.73%. RdNBR was the most important feature, and the red edge bands of Sentinel 2 images had relatively high importance. Additional studies are needed to explore the sensitivity of different spatial scales satellite images for mapping fire severity at fine spatial scales across various ecosystems. [ABSTRACT FROM AUTHOR]

Sphagnum bogs in Australia are small, with a limited distribution, but of high conservation value. They are restricted to cool, wet environments that are typically fire free and are poorly adapted to recover from fire disturbance, unlike most Australian flora. Increased fire activity due to anthropogenic climate change is threatening Sphagnum bogs. This increased threat has stimulated interest in their restoration. Compared with the northern hemisphere, there have been few studies of the ecology of Sphagnum restoration in the southern hemisphere. Here, we report on a field experiment in Tasmania, in an area burned by an extensive fire in 2016. We investigated the role of shade, fertilizer and transplants, factors demonstrated to be important in the restoration of burnt bogs on the Australian mainland. Treatments commenced three to 4 years after the fire. Overall, we found that fire‐damaged Sphagnum recovers very slowly, and that there was no recovery in severely burned areas. The addition of shade increased recovery of damaged Sphagnum, but fertilizer was harmful, even to healthy Sphagnum. Transplants in fire‐killed Sphagnum grew poorly in both moderately and severely burnt Sphagnum areas. Our findings support the use of shading in post‐fire Sphagnum recovery projects, although further work is required to determine the optimal approach and duration of providing shade. [ABSTRACT FROM AUTHOR]

Mega‐fires in the Australian summer of 2019–20 resulted in the largest ever documented forest fire extent. These fires impacted many species, but individual responses remain poorly known, making assessments of their conservation status and ongoing threats uncertain. We assessed the influence of the 2019–20 mega‐fires on habitat occupancy in the golden‐tipped bat Phoniscus papuensis, a specialist which roosts in suspended birds' nests and occurs in relictual Gondwanan rainforest not typically exposed to fire. We used trapping and accounted for nightly detection probability (lower detection with increasing rainfall) to estimate site occupancy. Occupancy increased with the local (1 km buffer surrounding each site) extent of rainforest, gullies and unburnt forest. The model predicted a strong negative effect of fire in the surrounding buffer, with occupancy reduced from >90% at sites with suitable habitat (extensive rainforest and gully systems) surrounded by unburnt forest to 20% when the entire surrounding area was burnt (regardless of severity). Gully rainforest sites surrounded by a mixture of burnt and unburnt forest were modelled to have intermediate occupancy values. On average, fire severity mapping revealed that 22% of rainforest in the 1 km buffer surrounding our burnt sites was unburnt, 61% had a low severity burn, while 17% experienced a high severity burn. The lower occupancy of P. papuensis in burnt rainforest was associated with a reduction in the abundance of suspended bird nests, a critical resource used for day‐roosting. Our results quantify the effects of extreme fire events on animal populations in rainforest that is normally unaffected by fire. The large extent of rainforest burnt during the 2019–20 Australian season of 'mega‐fires' and its strong negative effect on occupancy highlights the vulnerability of animal species reliant on fire‐sensitive habitat to a climate‐change driven increase in such extreme fire events. [ABSTRACT FROM AUTHOR]

The ability to measure the ecological effects of understory fire in the Amazon on a landscape scale remains a frontier in remote sensing. The Global Ecosystem Dynamics Investigation's (GEDI) LiDAR data have been widely suggested as a critical new tool in this field. In this paper, we use the GEDI Simulator to quantify the nuanced effects of understory fire in the Amazon, and assess the ability of on-orbit GEDI data to do the same. While numerous ecological studies have used simulated GEDI data, on-orbit constraint may limit ecological inference. This is the first study that we are aware of that directly compares methods using simulated and on-orbit GEDI data. Simulated GEDI data showed that fire effects varied nonlinearly through the canopy and then moved upward with time since burn. Given that fire effects peaked in the mid-canopy and were often on the scale of 2 to 3 m in height difference, it is unlikely that on-orbit GEDI data will have the sensitivity to detect these same changes. [ABSTRACT FROM AUTHOR]

Fast and accurate fire severity mapping can provide an essential resource for fire management and studying fire-related ecological and climate change. Currently, mainstream fire severity mapping approaches are based only on pixel-wise spectral features. However, the landscape pattern of fire severity originates from variations in spatial dependence, which should be described by spatial features combined with spectral features. In this paper, we propose a morphological attribute profiles-based spectral–spatial approach, named Burn Attribute Profiles (BAP), to improve fire severity classification and mapping accuracy. Specifically, the BAP method uses principal component transformation and attributes with automatically determined thresholds to extract spatial features, which are integrated with spectral features to form spectral–spatial features for fire severity. We systematically tested and compared the BAP-based spectral–spatial features and spectral index features in the extremely randomized trees machine learning framework. Sentinel-2 imagery was used for seven fires in the Mediterranean region, while Landsat-8 imagery was used for another seven fires in the northwestern continental United States region. The results showed that, except for 2 fires (overall accuracy (OA) for EMSR213_P: 59.6%, EL: 59.5%), BAP performed well for the other 12 fires (OA for the 2 fires: 60–70%, 6 fires: 70–80%, 4 fires: >80%). Furthermore, compared with the spectral indices-based method, the BAP method showed OA improvement in all 14 fires (OA improvement in Mediterranean: 0.2–14.3%, US: 4.7–12.9%). Recall and Precision were also improved for each fire severity level in most fire events. Moreover, the BAP method improved the "salt-and-pepper" phenomenon in the homogeneous area, where the results are visually closest to the reference data. The above results suggest that the spectral–spatial method based on morphological attribute profiles can map fire severity more accurately. [ABSTRACT FROM AUTHOR]

Background: Fire-caused tree mortality and spatial pattern are crucial for evaluating forest dynamics and developing management prescriptions. Aims: We investigated direct fire effects on spatial distribution and mortality of Dahurian larch (Larix gmelinii Rupr.) and assessed the Ryan and Amman (R–A) model performance and the importance of immediate mortality predictors. Methods: We analysed spatial patterns of fire-killed and surviving trees of three size classes in plots that burned at low- to high-severity using pair-correlation functions and tree mortality with the R–A model and generalised linear mixed models. Key results: The mixed-severity fire caused strong density-dependent mortality and more aggregated surviving tree patterns at short distances. The R–A model generally performed acceptably, and crown scorch and bole char height were critical predictors determining post-fire tree mortality. Conclusions: Fire-caused tree mortality and spatial patterns are controlled primarily by spatial variation in tree size and biological and structural characteristics. The prediction biases of the R–A model arose primarily from the intrinsic traits of Dahurian larch and the imbalanced dataset. Fine-scale neighbourhood density might be a fundamental priority for fire management and restoration. Implications: This study could possibly improve mechanistic understanding of spatial pattern development and tree mortality in similar fire-prone conifer forests. A larch-dominated forest exhibited density-dependent post-fire mortality patterns at short distances and increased aggregation among surviving trees post-fire. A widely used USA tree mortality model performed acceptably for this species. This study could potentially inform management strategies for conifer forests with similar structures and fire regimes. [ABSTRACT FROM AUTHOR]

Background: Salvage logging is commonly carried out after forest fires, and mastication of the logging slash is usually prescribed to reduce the risk of infestation by insect pests in NW Spain. Aims: To evaluate how post-fire masticated slash depth affected vegetation regeneration (cover, diversity and load) and soil variables (soil organic carbon and soil compaction). Methods: In October 2017, a fire that completely burned tree crowns and caused moderate soil burn severity was selected for study. At the end of 2017, the burned trees were logged and logging slash was masticated. Twenty plots were established in June 2020 in those areas to analyse the effect of the depth of masticated slash on soil compaction, vegetation recovery, fuel distribution and carbon accumulation. Key results: The depth of masticated slash did not affect soil compaction, total vegetation cover or species diversity. Mean pine seedling density was significantly higher areas where the masticated slash depth was lower. Fuel loads and soil carbon content did not vary with the depth of masticated slash. Conclusions: A lower masticated slash depth seems to be more favourable for pine regeneration. Implications: These results may be useful for managers to favour natural regeneration in similar pine stands after fire. This study aimed to evaluate how post-fire masticated slash depth affected vegetation regeneration to provide information for forest management planning. The masticated slash depth did not have significant effects on vegetation cover or species diversity 2.5 years after treatments. A lower slash depth favoured pine regeneration. [ABSTRACT FROM AUTHOR]