Modeling the Thermal Zones and Biodiversity on the High Mountains of Meganesia: The Importance of Local Differences

Alpine areas in Meganesia occur on maritime and continental mountains, and range from tropical to warm and cool temperate. At their current treelines, we measured soil temperatures, which were found to be within the bounds for treeline temperatures worldwide. We modeled areas above these alpine treelines using (1) a growing season mean synoptic temperature of 6.4 °C at treeline and (2) monthly temperature extremes. It was possible to adjust the threshold temperatures of the growing season model until predicted areas approximated observed alpine areas for New Guinea, the Australian mainland Snowy Mountains, and Tasmania, but meaningful predictions could not be made for the unknown alpine area of the Victorian Alps. The temperature extreme model was unsuitable for New Guinea and Tasmania but gave better predictive results for the Victorian Alps. We correctly predicted a strong relationship between alpine area and number of alpine vascular plant species and between regional area and number of terrestrial vertebrate species. However, there was no clear relationship between alpine area and alpine terrestrial vertebrate richness. Differences among the mountains were better explained by climatic extremes and insolation. If local explanations are required to model alpine vertebrate fauna, it is difficult to build robust global models and consequently make general predictions of climate change impacts