A field test of mechanisms underpinning animal diversity in recently burned landscapes.
Planned burning generates different types of pyrodiversity, however, experimental tests of how alternative spatial patterns of burning influence animal communities remain rare. Field tests are needed to understand the mechanisms through which spatial variation in planned fire affects fauna, and how fire can be applied to benefit biodiversity. We tested five hypotheses of how fire-driven variation in habitat composition and configuration affects fauna at fine scales. Small mammal, reptile and invasive predator activity was monitored at 12 burnt and eight unburnt sites through the year following a large, planned burn in semi-arid 'mallee' woodlands of southern Australia. We explored measures of burnt or unburnt habitat ('habitat status'); amount of unburnt vegetation ('habitat amount'); interspersion of burnt and unburnt patches ('habitat complementation'); distance to external or internal unburnt vegetation ('habitat connectivity'); and unburnt patch size and local vegetation cover ('habitat refuge'). Generalized linear models were used to test the influence of each variable on capture rates of three small mammal and 11 reptile species; activity of the introduced red fox (Vulpes vulpes); and species richness of native animals. We found strong support for the habitat status hypothesis and moderate support for four hypotheses relating to spatial patterns of fire. Reptile assemblages varied between burnt and unburnt sites, and relationships were identified between abundance of one or more reptile species and each measure of spatial variation. Reptile species richness was higher at unburnt sites and at sites with more unburnt vegetation in the surrounding area. Sites that were less connected to unburnt vegetation had fewer reptile species. Mammals did not have clear relationships with fine-scale fire patterns. Synthesis and applications. Application of planned fire to promote biodiversity is globally important. We show that retaining unburnt areas and well-connected habitat refuges is important for reptile diversity. We also found that several species of small mammals and reptiles appear resilient to the fine-scale patterns of planned fire experienced in this study, despite activity of introduced predators. The diversity of animals can remain relatively high in areas subject to planned fire, provided that internal and external habitat refuges are retained.