Climate Change and Long-Term Fire Management Impacts on Australian Savanna

Abstract:

Tropical savannas cover a large proportion of the Earth's land surface and many people are dependent on the ecosystem services that savannas supply. Their sustainable management is therefore crucial. Due to the complexity of vegetation dynamics, the impacts of climate change and land use on savannas are highly uncertain. Here, we use a dynamic vegetation model, the aDGVM, to project how climate change and fire management influence vegetation in northern Australian savannas in 2100. We show that under future climate conditions, vegetation can store more carbon than under ambient conditions, despite substantial changes in fire regimes. Changes in rainfall seasonality influence future carbon storage but do not turn vegetation into a carbon source, suggesting that CO₂ fertilization is the main driver of vegetation change. The application of prescribed fires with varying return intervals and burning season, influences vegetation dynamics and fire induced carbon and greenhouse gas emissions. Carbon sequestration is maximized with early dry season fires and long fire return intervals, grass productivity is maximized with late dry season fires at an intermediate fire return intervals. The study has implications for management policy across Australian savannas because it can contribute to identifying fire management strategies that optimize grazing yield, carbon sequestration and greenhouse gas emissions. This knowledge is crucial to maintain important ecosystem services of Australian savannas.