Complex habitat drives mammal communities in a flammable landscape

Abstract

In flammable ecosystems biodiversity can be influenced by multiple drivers, and conservation management requires knowledge of their relative influence. For example, land managers often manipulate fire regimes to increase environmental heterogeneity and promote biodiversity. However, the influence of fire relative to other drivers of biodiversity is often unknown. In this study, we used a temporally replicated dataset to (a) examine the effect of climate, topography, time since fire and habitat structure on mammal alpha- and beta-diversity and (b) assess the consistency of these responses through time. We surveyed ground-dwelling mammals within the Otway Ranges of Australia over four periods between 2010 and 2017. Alpha- and beta-diversity were most strongly influenced by habitat complexity. Alpha-diversity showed a strong positive relationship with habitat complexity, while there was a constant change in beta-diversity along the habitat complexity gradient. The remaining drivers, particularly time since fire, had relatively low influence. Alpha- and beta-diversity were often influenced by different environmental variables, emphasising the value of assessing multiple levels of species diversity. Finally, each survey period predicted the observed data in other years poorly, reflecting temporal change in response patterns, and demonstrating multiple years of data may be needed to characterise the response of species diversity to potential drivers. Overall, our results show environmental variables – particularly habitat structure – are more influential than time since fire in driving species diversity. Land managers seeking to manage species diversity may do so indirectly, through the influence of fire on habitat complexity. However, to do so effectively requires greater understanding of how fire interacts with other factors to influence floristics and vegetation recovery.