Beyond Deforestation: Climate Extremes as Emerging Primary Risks for Arboreal Folivores - A Systematic Review

Abstract Aim: Climate extremes are increasingly recognized as important pressures on wildlife, but their significance relative to habitat loss, degradation, and fragmentation remains poorly synthesized for arboreal folivores. We systematically reviewed the global evidence to assess which climate extremes have been studied, how they co-occur with non-climatic threats, and what outcomes and conservation implications have been reported. Methods: Following PRISMA 2020 guidelines, we searched PubMed, Web of Science, and Scopus through December 2024. After de-duplication and dual-reviewer screening, eligible studies were coded for climate extremes, non-climatic threats, taxon, geography, study design, and outcome polarity. Climate-extreme terminology was harmonized using IPCC/WMO-consistent definitions. We summarized patterns of threat co-occurrence and outcomes and used pre-specified bias-reduced logistic models to explore whether the number of climate extremes referenced was associated with adverse outcomes. Results: Of 3,206 records identified, 210 studies published between 1985 and 2024 met the inclusion criteria. Fifty-three studies (25.2%) explicitly addressed at least one climate extreme. Drought (n = 28), heat or heatwaves (n = 27), and wildfire (n = 27) were the most frequently reported extremes. Adverse outcomes were reported in 205 studies (97.6%), including 50 of 53 climate-extreme studies (94.3%), and adverse outcomes increased with the number of climate extremes referenced. Climate extremes frequently occurred alongside habitat alteration, including degradation (approximately 60%), habitat loss (approximately 55%), and fragmentation (approximately 45%). The evidence base was strongly biased towards Australia and marsupials, particularly koalas, with comparatively limited evidence from cyclone- and flood-prone regions and for taxa such as colobines and sloths. Conclusions and implications: Climate extremes are increasingly represented in the evidence base for arboreal folivores and commonly occur within landscapes already affected by habitat alteration, indicating that conservation responses should address interacting stressors rather than climate hazards in isolation. Management options supported by the reviewed evidence include protecting and restoring habitat that provides canopy microclimate refugia, maintaining landscape connectivity, incorporating fire risk into habitat management, and developing contingency responses for extreme events. Future studies should use standardized definitions of climate hazards, quantify exposure and biological responses, and routinely report effect sizes to strengthen evidence-based decision-making and enable quantitative synthesis, particularly in under-represented regions and taxa.