An introduction to patterns of fire in arid and semi-arid Australia, 1998-2004

Fire is a crucial element in shaping our world, whether of natural or anthropogenic origin. These fires can have both positive and negative consequences and impacts on our natural environment, society and its economics, not to mention global climate. Previous analyses of fire regimes in arid and semi-arid Australia have been of limited spatial or temporal extent. This lack of knowledge has hampered attempts at effective fire management. Satellite imagery allows the continuous detection, monitoring and mapping of fires. Active fires can be detected as fire hotspots, and burned areas mapped as patches from the change of surface reflectance properties in successive images. Data from NOAA's advanced very high resolution radiometer (AVHRR) were used to assess the distribution, seasonality, frequency, number and extent of fire hotspots (FHS) and fire affected areas (FAA) across the entire arid and semi-arid country of Australia from 1998 to 2004. Utilising both of these fire datasets is important, as they complement each other and provide a more robust analysis of fire patterns. Between 1998 and 2004 almost 27% of arid and semi-arid Australia burnt at least once. The main trends in fire distribution follow latitudinal rainfall gradients. Regression analysis also shows a strong relationship with the pattern of antecedent rainfall. The seasonality of fire events varies between climate zones in accordance with the varying distribution of precipitation and temperature, which influence fuel accumulation and curing. For the first time we have a picture of fire patterns across the entire arid and semi-arid regions of the country. This includes several high fire years in certain areas following above-average rainfall. This analysis highlights similarities and differences between regions, giving policy makers and managers a basis from which to make more informed decisions in the present, and with which to compare future regimes.