Search Results (8)

The pyrodiversity–biodiversity (P–B) hypothesis posits that spatiotemporally variable fire regimes increase wildlife habitat diversity, and that the fine-grained mosaics resulting from small patchy fires enhance biodiversity. This logic underpins the patch mosaic burning (PMB) paradigm and reinforces the benefits of Indigenous fire management, which tends to promote pyrodiversity. However, tests of the P–B hypothesis and PMB paradigm are few. One of the most comprehensive field evaluations—a snapshot study of pre-existing fire mosaics in south-east Australian semi-arid mallee eucalypt woodlands—found little support. To explore the longer-term effects of fire mosaic grain size on habitat availability and biodiversity, we combined published data from the mallee study with a simple fire simulation. We simulated 500 years of landscape burning under different fire sizes. In the resulting mosaics, we assessed the proportional mixture and patch configuration of successional habitat states, then summarised habitat availability through time using a composite index based on the published fire history responses of 22 vertebrate taxa from the mallee study. Small fires formed fine-grained mosaics with a stable habitat mixture and with habitat diversity occurring at fine scales. Large fires formed coarse-grained mosaics with the opposite properties. The fine-grained mosaics maintained optimal habitat availability for vertebrate diversity over 500 years, while the fluctuating habitat mixture in the coarse-grained mosaics was unlikely to maintain maximum vertebrate diversity. Broadly, our results support the P–B hypothesis and justify further field-testing and evaluation of PMB programs to manage both pyrodiversity and biodiversity in the mallee and other flammable landscapes. Full article

The páramos have a great diversity of flora, including terricolous non-tracheophyte photoautotrophs (bryophytes and lichens). Bryophytes and lichens are very sensitive to environmental changes related to anthropogenic fires, livestock, and agricultural activities. We determined for the first time in Ecuador the effects of prescribed fires on the pyrodiversity of terricolous non-tracheophyte photoautotroph in a páramo of South Ecuador. Three permanent sampling plots (T1, T2, and control) were established, each with a dimension of 4 m × 20 m and separated by 3 m (T1: one with fire-induced uphill and T2: one with fire-induced downhill and one control). They were installed in three different blocks, obtaining a total of nine plots. Three samplings (2, 6, and 12 months) were carried out in each plot, where the cover and richness of terricolous bryophytes and lichens were estimated in 216 quadrats of 20 × 30 cm. A total of 27 species (11 lichens and 16 bryophytes) were studied, where the lichen families, that is, Cladoniaceae and Baeomycetaceae, as well as the bryophytes families, namely, Dicranaceae, Jungermanniaceae, Bartramiaceae, Rhacocarpaceae, and Pallaviciniaceae, have been recorded as pioneers in areas under fire effects. Richness and diversity (calculated using the Shannon–Weaver and Simpson indexes) were affected by fire treatments; on the other hand, monitoring time (M3) positively affected species diversity. The composition of terrestrial non-tracheophyte photoautotroph communities showed slight changes between the control and T1 and T2, but the changes were more marked with time after the burns (M1 vs. M3), related to fire severity. Therefore, terricolous lichen and bryophyte communities (richness and diversity) can be used as model organisms for the assessment of the effects of prescribed fires on tropical páramos for subsequent management and conservation. Full article

Fire occurrence affects the distribution of key resources for fauna in natural ecosystems worldwide. For fire management strategies adequate for biodiversity conservation, the understanding of how species respond to fire-induced changes is essential. In this study, we investigated the role of fire regimes on spaces used by medium and large mammals at multiple spatial scales (0.8 ha to 78.5 ha) in a fire-prone savanna ecosystem (Brazilian Cerrado). We sampled mammals using 60 camera traps distributed in 30 sampling units located in grassland and typical savanna formations. We applied single-species occupancy models and AIC-based model selection to assess how mammals use the space in response to pyrodiversity (both diversity of fire frequencies and diversity of fire ages), the proportion of recently burned area, and the proportion of long-unburned area while accounting for detectability. Our results showed that fire regime variables affected the study species differently. Deer species used the space regardless of mosaic pyrodiversity and the proportion of specific fire ages. Fire-related variables, however, affected space use by tapirs and maned wolves. Tapirs preferred to use fire mosaics with lower diversity of fire frequencies, whereas maned wolves more intensively used mosaics with high fire age diversity and a high proportion of recently burned areas. Based on our findings, we recommend that fire management targeting specific mammal species should not necessarily focus on maximum pyrodiversity. Instead, we suggest a management strategy combining “patch mosaic burning” with the maintenance of specific fire-age patches suitable for different species’ requirements. Full article

A neglected dimension of the fire regime concept is fire patchiness. Habitat mosaics that emerge from the grain of burned and unburned patches (pyrodiversity) are critical for the persistence of a diverse range of plant and animal species. This issue is of particular importance in frequently burned tropical Eucalyptus savannas, where coarse fire mosaics have been hypothesized to have caused the recent drastic population declines of small mammals. Satellites routinely used for fire mapping in these systems are unable to accurately map fine-grained fire mosaics, frustrating our ability to determine whether declines in biodiversity are associated with local pyrodiversity. To advance this problem, we have developed a novel method (we call ‘double-differenced dNBR’) that combines the infrequent (c. 16 days) detailed spatial resolution Landsat with daily coarse scale coverage of MODIS and VIIRS to map pyrodiversity in the savannas of Kakadu National Park. We used seasonal Landsat mosaics and differenced normalized burn ratio (dNBR) to define burned areas, with a modification to dNBR that subtracts long-term average dNBR to increase contrast. Our results show this approach is effective in mapping fine-scale fire mosaics in the homogenous lowland savannas, although inappropriate for nearby heterogenous landscapes. Comparison of this methods to other fire metrics (e.g., area burned, seasonality) based on Landsat and MODIS imagery suggest this method is likely accurate and better at quantifying fine-scale patchiness of fire, albeit it demands detailed field validation. Full article

At the landscape scale, the Mediterranean region is a mosaic of habitats occupied by plants and animals with different resilience to fire. One of these habitats, the pine plantation, is characterized by its structural simplification and susceptibility to fire. Despite its high flammability, few studies have compared the response of animal communities between pine plantations and other autochthonous woodlands. For five years after a large fire in southwestern Europe, we surveyed reptiles in two natural habitats (oak forest, scrubland) and a pine plantation managed with salvage logging, a post-fire practice which consists of the complete harvesting and removal of death burnt trees. Reptile abundance and species composition were examined to assess differences in the reptile community between these habitats. Differences between burnt and unburnt transects were limited to the first year after the fire, while, over the entire five-year period, differences in species composition and abundance were due to vegetation type instead of fire. The pine logged area showed a delay in the recovery of vegetation and also in the appearance of many reptile species after the fire. At the reptile species level, we found evidence of both positive responses to fire (for lizards with high heliothermic activity) and negative ones (for specialist snake species). Overall, our results confirm the resilience of the reptile community to fire. The mosaic of habitats in the Mediterranean region and the openness caused by fire can increase the reptile biodiversity (landscape- plus pyro-diversity effects), but some practices such as salvage logging coupled with fire regime shifts (larger and more frequent fires) can compromise the conservation of the biodiversity in fire-prone regions. Full article

Land use and fire exclusion have influenced ecosystems worldwide, resulting in alternative ecosystem states. Here, I provide two examples from the southeastern United States of fire-dependent open pine and pine-oak forest loss and examine dynamics of the replacement forests, given continued long-term declines in foundation longleaf (Pinus palustris) and shortleaf (Pinus echinata) pines and recent increases in commercial loblolly (Pinus taeda) and slash (Pinus elliottii var. elliottii) pines. Shortleaf pine-oak forest historically may have been dominant on about 32 to 38 million ha, a provisional estimate based on historical composition of 75% of all trees, and has decreased to about 2.5 million ha currently; shortleaf pine now is 3% of all trees in the northern province. Longleaf pine forest decreased from about 30 million ha, totaling 75% of all trees, to 1.3 million ha and 3% of all trees in contemporary forests of the southern province. The initial transition from open pine ecosystems to closed forests, primarily comprised of broadleaf species, was countered by conversion to loblolly and slash pine plantations. Loblolly pine now accounts for 37% of all trees. Loss of fire-dependent ecosystems and their foundation tree species affect associated biodiversity, or the species that succeed under fire disturbance. Full article

Paleofire studies frequently discount the impact of human activities in past fire regimes. Globally, we know that a common pattern of anthropogenic burning regimes is to burn many small patches at high frequency, thereby generating landscape heterogeneity. Is this type of anthropogenic pyrodiversity necessarily obscured in paleofire records because of fundamental limitations of those records? We evaluate this with a cellular automata model designed to replicate different fire regimes with identical fire rotations but different fire frequencies and patchiness. Our results indicate that high frequency patch burning can be identified in tree-ring records at relatively modest sampling intensities. However, standard methods that filter out fires represented by few trees systematically biases the records against patch burning. In simulated fire regime shifts, fading records, sample size, and the contrast between the shifted fire regimes all interact to make statistical identification of regime shifts challenging without other information. Recent studies indicate that integration of information from history, archaeology, or anthropology and paleofire data generate the most reliable inferences of anthropogenic patch burning and fire regime changes associated with cultural changes. Full article

Conserving animals and plants in fire-prone landscapes requires evidence of how fires affect modified ecosystems. Despite progress on this front, fire ecology is restricted by a dissonance between two dominant paradigms: ‘fire mosaics’ and ‘functional types’. The fire mosaic paradigm focuses on animal responses to fire events and spatial variation, whereas the functional type paradigm focuses on plant responses to recurrent fires and temporal variation. Fire management for biodiversity conservation requires input from each paradigm because animals and plants are interdependent and influenced by spatial and temporal dimensions of fire regimes. We propose that better integration of animal-based and plant-based approaches can be achieved by identifying common metrics that describe changes in multiple taxa; linking multiple components of the fire regime with animal and plant data; understanding plant-animal interactions; and incorporating spatial and temporal characteristics of fires into conservation management. Our vision for a more integrated fire ecology could be implemented via a collaborative and global network of research and monitoring sites, where measures of animals and plants are linked to real-time data on fire regimes. Full article