The Effects of Wildfire on Mortality and Resources for an Arboreal Marsupial: Resilience to Fire Events but Susceptibility to Fire Regime Change

Sam C Banks,Emma J Knight,David B Lindenmayer,David Blair,Lachlan Mcburney,Yan Ropert-Coudert

doi:10.1371/journal.pone.0022952

Abstract

BackgroundBig environmental disturbances have big ecological effects, yet these are not always what we might expect. Understanding the proximate effects of major disturbances, such as severe wildfires, on individuals, populations and habitats will be essential for understanding how predicted future increases in the frequency of such disturbances will affect ecosystems. However, researchers rarely have access to data from immediately before and after such events. Here we report on the effects of a severe and extensive forest wildfire on mortality, reproductive output and availability of key shelter resources for an arboreal marsupial. We also investigated the behavioural response of individuals to changed shelter resource availability in the post-fire environment.Methodology/Principal FindingsWe fitted proximity-logging radiotransmitters to mountain brushtail possums (Trichosurus cunninghami) before, during and after the 2009 wildfires in Victoria, Australia. Surprisingly, we detected no mortality associated with the fire, and despite a significant post-fire decrease in the proportion of females carrying pouch young in the burnt area, there was no short-term post-fire population decline. The major consequence of this fire for mountain brushtail possums was the loss of over 80% of hollow-bearing trees. The types of trees preferred as shelter sites (highly decayed dead standing trees) were those most likely to collapse after fire. Individuals adapted to resource decline by being more flexible in resource selection after the fire, but not by increased resource sharing.Conclusions/SignificanceDespite short-term demographic resilience and behavioural adaptation following this fire, the major loss of decayed hollow trees suggests the increased frequency of stand-replacing wildfires predicted under climate change will pose major challenges for shelter resource availability for hollow-dependent fauna. Hollow-bearing trees are typically biological legacies of previous forest generations in post-fire regrowth forests but will cease to be recruited to future regrowth forests if the interval between severe fires becomes too rapid for hollow formation.

Highlights

Knowledge gaps on the proximate effects of disturbance on faunaNatural disturbance events such as wildfires, tsunamis or volcanic eruptions can have widespread and long-term effects on ecosystems [1,2,3]
Key knowledge gaps relate to the proximate effects of disturbances on demography, short and long-term resource availability and the adaptive responses of species to such environmental changes [9,10]
We quantified the effects of a major wildfire, the February 2009 Black Saturday wildfires in Victoria, Australia, on short-term survival, reproductive output and resource availability for the arboreal mountain brushtail possum (Trichosurus cunninghami)

Summary

Introduction

Knowledge gaps on the proximate effects of disturbance on faunaNatural disturbance events such as wildfires, tsunamis or volcanic eruptions can have widespread and long-term effects on ecosystems [1,2,3]. Key knowledge gaps relate to the proximate effects of disturbances on demography, short and long-term resource availability and the adaptive responses of species to such environmental changes [9,10]. These knowledge gaps are relevant to high intensity disturbances such as severe wildfires, as the unpredictable nature of such events makes reliable studies (e.g. comparing affected and unaffected areas before and after disturbance) difficult to implement [11]. Understanding the proximate effects of major disturbances, such as severe wildfires, on individuals, populations and habitats will be essential for understanding how predicted future increases in the frequency of such disturbances will affect ecosystems. We investigated the behavioural response of individuals to changed shelter resource availability in the post-fire environment

Methods

Results

Conclusion