Effects of Climate Change on the endangered rainforest shrub Triunia robusta (Proteaceae), endemic to Southeast Queensland, Australia

The potential impacts of climate change on plant species are predicted to be extensive, and those with small populations and low dispersal are predicted to be among the most vulnerable to climate change. Many studies have modelled the potential impacts of climate change on plant population persistence. However, the majority are based on geographical and a-biotic factors and seldom take into account the potential effects on species population dynamics. Triunia robusta is a long-lived, endangered subtropical rainforest shrub which was reported to have less than 400 adult plants across 11 small populations in Southeast Queensland of Australia. This research investigated the potential impacts of climate change on the population viability of T. robusta by integrating species distribution models (SDM) and population models using a coupled model approach. This study re-censused all known populations from a previous 1999 survey and six newly discovered populations. Surveys were undertaken to identify potential dispersers, and dispersal and predation dynamics in both natural and green house environments. The potential impacts of climate change on the species habitat distribution were investigated at both continental and regional scales using a species distribution modelling approach. Finally, the potential effects of climate change on population viability of the species were examined over a 90-year period using integrated metapopulation models. Dramatic contraction of the species habitat range was predicted within the species distribution range, with the habitat areas showing southward contraction toward higher elevations into the Sunshine Coast hinterland. Some populations are already in decline particularly in the northern range, where populations showed much lower growth and reproductive rates than those in the southern range, possibly early signs of climate change impacts. In contrast, larger populations (approximately 100 or more plants including seedlings) in the southern range have increased over a ten year period, highlighting the importance of maintaining larger population sizes for a long-term survival. The population viability analyses revealed high vulnerability of small populations (