Extensive range contraction predicted under climate warming for two endangered mountaintop frogs from the rainforests of subtropical Australia

Abstract

Montane ecosystems cover approximately 20% of the Earth's terrestrial surface and are centres of endemism. Globally, anthropogenic climate change is driving population declines and local extinctions across multiple montane taxa, including amphibians. We applied the maximum entropy approach to predict the impacts of climate change on the distribution of two poorly known amphibian species (Philoria kundagungan and Philoria richmondensis) endemic to the subtropical uplands of the Gondwana Rainforests of Australia, World Heritage Area (GRAWHA). Firstly, under current climate conditions and also future (2055) low and high warming scenarios. We validated current distribution models against models developed using presence-absence field data. Our models were highly concordant with known distributions and predicted the current distribution of P. kundagungan to contract by 64% under the low warming scenario and by 91% under the high warming scenario and that P. richmondensis would contract by 50% and 85%, respectively. With large areas of habitat already impacted by wildfires, conservation efforts for both these species need to be initiated urgently. We propose several options, including establishing ex-situ insurance populations increasing the long-term viability of both species in the wild through conservation translocations.

Patterns of species richness and turnover in endemic amphibians of the Guineo‐Congolian rain forest

“…Bioclimatic factors such as precipitation and temperature are especially likely to influence ecological processes and biological functioning in amphibians (Olden & Rooney, 2006). Variables related to extreme environmental conditions (precipitation of the warmest quarter and mean temperature of the wettest quarter) emerged as important in explaining the turnover in GC endemic amphibians, similar to previous studies on amphibians (Bolitho & Newell, 2022; Guo et al, 2021). Precipitation of the wettest quarter has also been linked to both tree diversity and water availability (Soares & Brito, 2007).…”

Drought, fire, and rainforest endemics: A case study of two threatened frogs impacted by Australia's “Black Summer”

“…Our results indicate that Philoria favor the coolest and wettest parts of the landscape, consistent with earlier work (Bolitho et al, 2021; Hollis, 2003; Knowles et al, 2004; Willacy, 2014). As such, forecast increases in temperature, evaporation and rainfall variability (Steffen, 2009) and reduced moisture availability from cloud‐stripping (Laidlaw et al, 2011, 2022) represent a major threat for these high‐elevation species, with no capacity for upslope migration (Bolitho & Newell, 2022). As evidenced by the 2019/2020 fires, climate drying facilitates novel fire incursion into rainforest habitats, which could cause direct frog mortality, while also degrading riparian breeding habitat.…”

“…Deepening droughts and novel fires represent a significant threat to P. kundagungan and P. richmondensis , just as they do to many mountain‐top and/or mesic‐adapted species susceptible to climate change (Bolitho & Newell, 2022). To conclude, we argue that both short‐ and long‐term management pathways exist to confront these threats, including ongoing monitoring to track responses to these threats, conservation planning that explicitly seeks to prepare for their impact, and targeted conservation actions that ameliorate other threatening processes and increase population resilience.…”

“…The reliance of Philoria on moist or saturated microhabitats within rainforest and adjoining mesic forest, suggests that they may be particularly sensitive to increased drought and novel fire under climate change (Bolitho & Newell, 2022; Mahony et al, 2023; Newell, 2018). This study sought to assess the impact of the “Black Summer” fires and the severe drought associated with them on two species from the Gondwana Rainforests of Australia World Heritage Area— P. kundagungan and P. richmondensis .…”

Bioacoustic Monitoring Reveals the Calling Activity of an Endangered Mountaintop Frog (Philoria kundagungan) in Response to Environmental Conditions

“…The Gondwana rainforests of eastern Australia, a network of World Heritage listed protected areas, is one example of an ecosystem whose amphibian inhabitants are beginning to come under pressure from climate change [17]. Among the endangered species that occupy these forests are six of the seven species described within the genus Philoria.…”