The impacts of Climate Change on the Rainforest Vertebrates of the Australian Wet Tropics

Abstract - Climate change has exposed biodiversity to unprecedented conditions, with tropical ecosystems particularly vulnerable to its effects. This thesis investigates the multifaceted impacts of climate change on tropical montane ecosystems, focusing on abundance-suitability relationships, community reshufiling dynamics, population responses to climate change, biogeo chemical dynamics, and the underlying physiological mechanisms driving population declines. Drawing on three decades of region-wide monitoring data in the Australian Wet Tropics, this research bridges critical gaps in our understanding of how climate change leads to biodiversity erosion in tropical montane regions, with a particular focus on rainforest birds and ringtail possums. Delving into the multidimensional nature of climate change, I examine the biological responses to the press and pulse of climate trends and extreme events through the lens of population dynamics. I highlight an unequivocal link between climate change and population alteration for rainforest birds and ringtail possums. However, I uncovered substantial differences in species’ abilities to track climate change, with rainforest birds primarily influenced by gradual warming and precipitation changes (presses), while low-dispersal ringtail possums succumb to extreme heatwaves (pulse). Moreover, my research unravels the underlying mechanisms of climate-induced population collapse, demonstrating how climate change directly reduces animal fitness. By integrating experimental studies and ecological modelling, this study provided valuable insights into the causallinks between environmental change and population declines, with a focus on rainforest ringtail possums. Specifically, it reveals that the impacts of climate change on ringtail populations are fundamentally linked to reductions in survival and recruitment resulting from increased overheating, dehydration, and reduced foraging performance. In conclusion, my thesis advances our understanding of the complexities of climate change impacts on tropical montane ecosystems and provides a roadmap for evidence-based conservation actions.