MTSRF

Project 2.5ii.4

Assessment of climate change vulnerability for Wet Tropics vertebrates

Project Leader: Prof Steve Williams, JCU

This MTSRF-funded project has made significant advancements in our understanding of the relative extinction proneness and vulnerability of Wet Tropics vertebrate species to climate change. First, researchers have developed a single unified framework for assessing vulnerability that incorporates all major factors contributing to vulnerability, including elements relating to both sensitivity and exposure. Second, researchers have vastly improved our knowledge of the sensitivity and exposure of individual species to climate change. Specifically, researchers have employed improved modelling techniques to estimate geographic range size, incorporated uncertainty in projections from seven different global climate models, and used field measurements of abundance to generate estimates of relative change in population size. Researchers compiled detailed information of ecological characteristics of species to estimate the capacity of species to resist or bounce back from environmental perturbations, and catalogued microhabitat use that can influence exposure to stressful environmental conditions. Third, researchers have integrated all of this information into a single vulnerability assessment to identify a priority list of species most threatened by climate change. This has been a particularly high-profile MTSRF-funded project, generating eighteen scientific publications (with twelve more in review), seven articles in magazines and newspapers, 30 conference presentations and four workshops, as well as significant media coverage.

Physiological tolerances of arboreal mammals

Project Leader: Prof Steve Williams, JCU

How vulnerable are the arboreal mammals of the Wet Tropics to increases in temperature? MTSRF-funded researchers measured responses to changing ambient temperatures in three species - lemuroid, Herbert River and green ringtail possums. In lemuroid and green ringtails, body temperature rose linearly at temperatures above a certain threshold. The threshold temperature at which lemuroids allowed their body temperature to start rising was 28.5°C, and the rate at which their temperature rose was ~25% faster than green ringtail possums. The observed variations in the rate of temperature rise and threshold temperature between species match well with researchers’ expectations based on the differences in the altitudinal ranges occupied by each species. These rainforest ringtail possums are likely to be limited by temperature extremes and negatively impacted by increases in the frequency and severity of those extremes.

Inclusion of biotic interactions in species distribution models improves predictions under climate change: the northern bettong, its food resources and a competitor (Project 2.5ii.4s2)

Project Leader: Prof Steve Williams, JCU

A MTSRF Student Scholarship enabled this study of the influence of biotic interactions on predicted current and future distributions of an endangered marsupial, the northern bettong (Bettongia tropica). Climatic models were developed independently for each of the northern bettong, two of its food resources, and a likely competitor. To determine how the inclusion of biotic interactions altered predicted distributions, northern bettong models were augmented by including estimates of climate suitability for the food resources and competitor, and then compared with those of the climate-only model. Differences in predictions were quantified with a ‘global’ metric to test whether predictions were significantly different, and a ‘local’ metric to identify where they differed. Inclusion of biotic interactions improved model performance and provided the most ecologically realistic distributions. Below 3.0 °C increase in climatic warming, predicted northern bettong models differed only in the margins of their predicted distribution, but beyond this level, predictions of models that incorporated biotic interactions diverged from those which did not.