The potential impacts of climate change on Australian subtropical rainforest

Abstract

The potential for anthropogenic climate change to impact upon native vegetation has emphasised the need for monitoring and for dynamic management regimes. Potential impacts are numerous, but will likely include the upslope movement of species’ ranges and increasing in situ turnover (compositional change) within plant assemblages. By assessing the potential impacts of climate change on subtropical rainforest communities in south-east Queensland through the establishment of an altitudinal transect, we aimed to establish the baseline composition of the vegetation and to develop two hypotheses against which climate change scenarios can be tested. The study identified existing high levels of turnover across tree assemblages from low to mid elevations absent at higher elevations and we predict: (1) subtropical rainforest communities which currently sit at the level of the cloud base (800–900 m) will experience increasing floristic turnover, and (2) novel vegetation communities will emerge as species move upslope in response to a changing climate. Monitoring floristic turnover as a surrogate for shifting climatic habitats may be confounded both by a lack of knowledge regarding the underlying turnover rates of rainforest communities and by the disparity in temporal scales of tree community turnover and accelerating anthropogenic climate change. The identification of ‘break points’ in the relationship between current vegetation communities and gradients of precipitation and temperature will allow better direction of monitoring efforts.