Changes in fire and carbon dynamics for projected future climates in the south eastern Australian high country

Abstract

There is mounting evidence that warmer and drier climates will result in an increase in fire activity. Lower fuel moistures result in an increase in fuel availability, and hence a greater probability of fire ignition success, with fires potentially burning for extended periods and at higher intensities. At present, the implications of these anticipated changes in fire regimes for carbon dynamics in Australian ecosystems are unclear. This study attempts to address this by combining the carbon dynamics model FullCAM and the landscape fire regime simulator FIRESCAPE to investigate the relative effects of projected climate changes on fire and carbon dynamics in the south eastern Australian high country. Three climate scenarios were simulated, representing the present climate and two projections for the year 2070. To encompass the range of climate change scenarios, both projected changes are based on anticipated global populations peaking mid-century, with one projection resulting from the use of fossil intensive technologies (A1FI), and the other projection resulting from the use of clean and resourceefficient technologies (B1). The 2 million hectare study landscape predominantly contains a diversity of native forest communities, with some areas containing native and pasture grasses, shrub communities and Pinus radiata plantations. Simulations using the FIRESCAPE / FullCAM hybrid model indicate that both fire regimes and carbon dynamics are sensitive to projected changes in climate, with the greatest deviances evident for the warmest and driest climate (A1FI). In simulations, the fire incidence, fire areas and fire intensities all increased as the climate became warmer and drier. Declines in carbon stocks were also evident across the landscape as shorter inter-fire intervals in all vegetation communities resulted in younger stand ages and hence reduced biomasses. Simulated carbon emissions increased for warmer and drier climates, reflecting the associated increase in fire activity. This study provides useful insights into changes in fire and carbon dynamics for the high country of south eastern Australia resulting from increased fire activity during warmer and drier climates.