Detecting climate change impacts on Antarctic terrestrial communities

Until recently continental Antarctica appeared to be little impacted by climate warming, thus biological changes were predicted to be relatively slow. Detecting the biological effects of Antarctic climate change has been hindered by the paucity of long-term data sets, particularly for organisms that have been exposed to these changes throughout their lives. We have shown that radiocarbon signals preserved along shoots of the dominant Antarctic moss flora can be used to determine accurate growth rates over a period of several decades, allowing us to explore the influence of environmental variables on growth and providing a dramatic demonstration of the effects of climate change. This work has revealed evidence of a drying trend in several of the extensive moss beds in the Windmill Islands region of East Antarctica. Free water is critical for moss growth and the length of the summer growing season is predominantly influenced by the length of time that water is available (a function of both snow bank inputs and the extent and severity of seasonal melt). Developing methodologies to monitor key environmental drivers such as water availability and moss health parameters as well as species composition across larger spatial scales is a key aim of our research. Long-term monitoring of vegetation communities along a moisture gradient at two sites in East Antarctica commenced in 2003 using three complementary sampling regimes; turf water content, digitally determined broad scale percent cover of vegetation and finer scale relative abundance of species, but these methodologies are labour intensive and limited to relatively small-scale plots. Recently we have also incorporated the use of unmanned aerial vehicles and high spatial resolution imaging spectroscopy to develop efficient methodologies to monitor Antarctic vegetation health and composition at a larger scale. These technologies could be invaluable in the development of an Antarctic terrestrial observing network.