A trait-based analysis for predicting impact of wildfires on frogs

Abstract

An increase in the frequency and intensity of catastrophic wildfires is associated with anthropogenic climate change. Wildfires are extreme environmental events that result in dramatic fluctuations in temperature and moisture, which are likely to disproportionately impact animals such as amphibians (Anura) whose distributions and ecology are strongly tied to climate. In response to the 2019/20 Australian summer wildfires, we used expert elicitation to analyse the traits of frogs that potentially influence fire sensitivity or resilience. Traits that were ranked high in terms of influencing fire sensitivity were range size, dominant adult habitat, reproductive mode, and relative abundance. While species restricted to cool, moist habitats are less exposed to the threat of wildfire, they had the highest sensitivity scores. This is due to their typically low fecundity, reliance on micro-refugia away from water for reproduction and shelter, and small, isolated distributions. The group considered least sensitive were those which occupy riparian zones as macro-refugia, which includes species with wide geographic distributions, general reproductive strategies, high fecundity, and moderate physiological capacity. Our findings suggest that it is the behavioural capacity of frogs to locate micro-refugia, a morphology that enables them to move into these safe spaces, and physiological adaptations to subsequently maintain water balance during and after wildfire that influence the probability of surviving wildfire. While many traits have evolved among amphibians to avoid climatic extremes and likely confer resistance to wildfire as “exaptations”, it remains unknown to what extent they protect populations from predicted hotter and drier climates. Our predictions should be tested by obtaining direct measures of the thermal and moisture buffering capacities of micro-refuges, along with the continued monitoring of species recovery post-fire, so that they can feedback into future trait-based analyses. We suggest that strategic management actions for mitigating the effect of climate-driven wildfires on amphibians should involve protection and enhancement of micro-refugia components of the landscape, which are used as shelter during times of heat and moisture stress, and provision of buffer zones around macro-refugia habitat, such as around streams.