Biophysical impacts of climate change on Australia’s forests. Contribution of Work Package 2 to the Forest Vulnerability Assessment
Authors: Belinda Medlyn, Melanie Zeppel, Niels Brouwers, Kay Howard, Emer O’Gara, Giles Hardy, Thomas Lyons, Li Li and Bradley Evans
This report presents a review of the literature on climate change impacts on Australian forests; identifying not only the predicted trends, but also a number of critical research gaps and discrepancies. Critical knowledge gaps include: i) major uncertainties surrounding future projections of water availability, particularly in regards to rainfall projections for many parts of the country and projections of evapotranspiration; ii) limited ecosystem scale data for Australian forests, particularly for long term forest monitoring, eddy covariance data, long-term ecological research sites, phenological records, ecosystem-scale manipulations, and paleological records; iii) gaps in our understanding of major response processes, such as on the effect of rising atmospheric CO2 concentration on the productivity and water use of Australian forests, and on the effects of long term drought on ecosystem processes and mortality thresholds. A key discrepancy identified by the literature review was that there was a real mismatch between predictions of vulnerability coming from bioclimatic and ecophysiological models. Bioclimatic models, based on observed climatic niches, found that many Australian species have narrow ranges and concluded they are very vulnerable to climate change. On the other hand, ecophysiological models, based on mechanistic understanding of climate impacts on plant processes, predicted widespread increases in forest production. The difference between these two approaches reflects the fact that the Australian research community does not yet understand, at a very fundamental level, what limits species distributions.