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Ecosystem engineers modify their environment and influence the availability of resources for other organisms. Burrowing species, a subset of allogenic engineers, are gaining recognition as ecological facilitators. Burrows created by these species provide habitat for a diverse array of other organisms. Following disturbances, burrows could also serve as ecological refuges, thereby enhancing ecological resistance to disturbance events. We explored the ecological role of Common Wombat (Vombatus ursinus) burrows using camera traps in forests of southeastern Australia. We compared animal activity at paired sites with and without burrows, from the same fire severity class and habitat. We examined how animal activity at Common Wombat burrows was affected by the 2019–20 Black Summer bushfires in Australia. We predicted that burrows would serve as hotspots for animal activity and as refuges in burned areas. The activity of several species including Bush Rat (Rattus fuscipes), Agile Antechinus (Antechinus agilis), Lace Monitor (Varanus varius), Painted Button-quail (Turnix varius), and Grey Shrike-thrush (Colluricincla harmonica) increased at sites where Common Wombat burrows were present, while other species avoided burrows. Species that were more active at burrows tended to be smaller mammal and bird species that are vulnerable to predation, whereas species that avoided burrows tended to be larger mammals that might compete with Common Wombat for resources. Species composition differed between sites with and without burrows, and burrow sites had higher native mammal species richness. The association of several species with burrows persisted or strengthened in areas that burned during the 2019–20 Black Summer bushfires, suggesting that Common Wombat burrows may act as ecological refuges for animals following severe wildfire. Our findings have relevance for understanding how animals survive, persist, and recover following extreme wildfire events. [ABSTRACT FROM AUTHOR]

Abstract Altered fire regimes can drive major and enduring compositional shifts or losses of forest ecosystems. In western North America, ponderosa pine and dry mixed‐conifer forest types appear increasingly vulnerable to uncharacteristically extensive, high‐severity wildfire. However, unburned or only lightly impacted forest stands that persist within burn mosaics—termed fire refugia—may serve as tree seed sources and promote landscape recovery. We sampled tree regeneration along gradients of fire refugia proximity and density at 686 sites within the perimeters of 12 large wildfires that occurred between 2000 and 2005 in the interior western United States. We used generalized linear mixed‐effects models to elucidate statistical relationships between tree regeneration and refugia pattern, including a new metric that incorporates patch proximity and proportional abundance. These relationships were then used to develop a spatially explicit landscape simulation model. We found that regeneration by ponderosa pine and obligate‐seeding mixed‐conifer tree species assemblages was strongly and positively predicted by refugia proximity and density. Simulation models revealed that for any given proportion of the landscape occupied by refugia, small patches produced greater landscape recovery than large patches. These results highlight the disproportionate importance of small, isolated islands of surviving trees, which may not be detectable with coarse‐scale satellite imagery. Findings also illustrate the interplay between patch‐scale resistance and landscape‐scale resilience: Disturbance‐resistant settings (fire refugia) can entrain resilience (forest regeneration) across the burn matrix. Implications and applications for land managers and conservation practitioners include strategies for the promotion and maintenance of fire refugia as components of resilient forest landscapes.

Wildfire refugia (unburnt patches within large wildfires) are important for the persistence of fire‐sensitive species across forested landscapes globally. A key challenge is to identify the factors that determine the distribution of fire refugia across space and time. In particular, determining the relative influence of climatic and landscape factors is important in order to understand likely changes in the distribution of wildfire refugia under future climates. Here, we examine the relative effect of weather (i.e. fire weather, drought severity) and landscape features (i.e. topography, fuel age, vegetation type) on the occurrence of fire refugia across 26 large wildfires in south‐eastern Australia. Fire weather and drought severity were the primary drivers of the occurrence of fire refugia, moderating the effect of landscape attributes. Unburnt patches rarely occurred under 'severe' fire weather, irrespective of drought severity, topography, fuels or vegetation community. The influence of drought severity and landscape factors played out most strongly under 'moderate' fire weather. In mesic forests, fire refugia were linked to variables that affect fuel moisture, whereby the occurrence of unburnt patches decreased with increasing drought conditions and were associated with more mesic topographic locations (i.e. gullies, pole‐facing aspects) and vegetation communities (i.e. closed‐forest). In dry forest, the occurrence of refugia was responsive to fuel age, being associated with recently burnt areas (<5 years since fire). Overall, these results show that increased severity of fire weather and increased drought conditions, both predicted under future climate scenarios, are likely to lead to a reduction of wildfire refugia across forests of southern Australia. Protection of topographic areas able to provide long‐term fire refugia will be an important step towards maintaining the ecological integrity of forests under future climate change. [ABSTRACT FROM AUTHOR]

Megafires, predicted to become more frequent with a changing climate, pose a global challenge for conservation. Initial assessments of the 2019/20 megafires of Australia's 'Black Summer' highlighted widespread, severe impacts for many species. Post-fire empirical investigations are critical to evaluate the distribution and conservation status of species. We investigated the impacts of megafire on the southern superb lyrebird (Menura novaehollandiae victoriae), a functionally important ecosystem engineer in forest ecosystems. We quantified the extent of lyrebird habitat burned at differing levels of severity, and how this varied among forest types. One-year post-fire, we carried out field surveys at 226 sites, stratified by forest type and fire severity, to assess the impact on lyrebirds. In total, 41.5 % (~2.1 million ha) of habitat was burned at differing levels of severity. Habitats of higher predicted quality were disproportionately affected. At one-year post-fire, lyrebirds were strongly affected by fire severity: their occurrence, as indicated by foraging activity, was greatly reduced in forests burned at high and low severity, but patchily burned forest differed little from unburned forest. Notably, foraging was almost completely absent from all sites that experienced high severity fire, except in rainforest. Rainforests (<1 % of distribution) have the greatest post-fire value for lyrebirds; they serve as local refuges for recolonization and are a priority for restoration efforts. Importantly, impacts of megafires are not uniform but vary greatly in relation to fire severity and forest type. Such knowledge is essential for long-term conservation of species of concern, including the identification and protection of refuges. [ABSTRACT FROM AUTHOR]

In this study, we report on shelter use by anurans during the dry season in the Pantanal, a large wetland in midwestern Brazil that is subject to periodical floods, dry periods, and sporadic fires. Field observations were made in the northern Pantanal from 2010 to 2013. We documented the use of underground burrows by seven frog species (about 20% of the known local anuran richness), including representatives of Hylidae, which tend to be arboreal. Most shelters used were galleries similar to those built by the crab Dilocarcinus pagei (Trichodactylidae). We also report on experimental and opportunistic observations on the use of termite thermal chimneys by the toad Rhinella bergi. Due to the prevalence of open areas in the Pantanal and absence of overlapping rocks and other types of shelter, underground galleries and tunnels in termite mounds may often be important refuges for anurans during the dry season and fires. Therefore, these tunnels may contribute significantly to the structuring of ground-dwelling anuran communities, which requires further studies. These studies should also address the indirect impacts of potential threats to the availability and integrity of underground burrows in the Pantanal, such as land management practices, uncontrolled crab exploitation, and extended extreme climatic events. [ABSTRACT FROM AUTHOR]

Altered fire regimes can drive major and enduring compositional shifts or losses of forest ecosystems. In western North America, ponderosa pine and dry mixed‐conifer forest types appear increasingly vulnerable to uncharacteristically extensive, high‐severity wildfire. However, unburned or only lightly impacted forest stands that persist within burn mosaics—termed fire refugia—may serve as tree seed sources and promote landscape recovery. We sampled tree regeneration along gradients of fire refugia proximity and density at 686 sites within the perimeters of 12 large wildfires that occurred between 2000 and 2005 in the interior western United States. We used generalized linear mixed‐effects models to elucidate statistical relationships between tree regeneration and refugia pattern, including a new metric that incorporates patch proximity and proportional abundance. These relationships were then used to develop a spatially explicit landscape simulation model. We found that regeneration by ponderosa pine and obligate‐seeding mixed‐conifer tree species assemblages was strongly and positively predicted by refugia proximity and density. Simulation models revealed that for any given proportion of the landscape occupied by refugia, small patches produced greater landscape recovery than large patches. These results highlight the disproportionate importance of small, isolated islands of surviving trees, which may not be detectable with coarse‐scale satellite imagery. Findings also illustrate the interplay between patch‐scale resistance and landscape‐scale resilience: Disturbance‐resistant settings (fire refugia) can entrain resilience (forest regeneration) across the burn matrix. Implications and applications for land managers and conservation practitioners include strategies for the promotion and maintenance of fire refugia as components of resilient forest landscapes. [ABSTRACT FROM AUTHOR]