Pre-contact Aboriginal, and contemporary fire regimes of the savanna landscapes of northern Australia: patterns, changes and ecological processes

• The paper provides a northern Australia savanna case study for assessing: first, differences (and similarities) between fire regimes operating under pre-contact traditional Aboriginal custodianship, and today under contemporary patterns of savanna landuse; and second, implications of such change(s) for biodiversity and ecological processes in northern Australia. • Ethnographic, historical and contemporary observations concerning traditional burning, while sparse and geographically biased towards coastal and sub-coastal regions, consistently show that burning was undertaken throughout the dry season following landscape patterns of the curing of grassy fuels. In northern and northwestern Australia at least, burning was concentrated particularly in the early-to mid-dry season under cooler, milder fire-weather conditions. Burning of clan estates was/is undertaken systematically and purposefully. Contemporary evidence (from coastal and sub-coastal situations) indicates at least half of any clan estate might be burnt in any one season. It is evident that, in accord with regional human population densities, burning was undertaken more frequently in higher rainfall coastal and sub-coastal regions. • Based on regional mapping of fires from satellite imagery (mostly NOAA-AVHRR and LANDSAT) from the 1980s, we can identify two broad contemporary patterns concerning the application of fire in northern Australia. In northwestern and northern Australia, and around the Gulf of Carpentaria, vast tracts are burnt annually, typically by intense wildfires late in the dry season. Conversely, elsewhere across northern Australia, but especially on more productive pastoral lands, landscape burning is infrequently applied. • Major differences (and similarities) between traditional Aboriginal and contemporary fire regimes may be summarised as follows: 1. Whereas burning was undertaken across northern Australia under Aboriginal custodianship, burning today is concentrated principally in non-pastoral, relatively high rainfall regions, especially in the Kimberley, in the Top End, and around the Gulf of Carpentaria; 2. Whereas burning in most regions traditionally was concentrated in the early-mid dry season, today it generally occurs mostly in the late dry season (LDS). Generalisation of the contemporary situation, however, masks considerable early dry season (EDS) burning in some limited locations (e.g. Darwin region, Kakadu and Litchfield National Parks); and inability to burn until later in the year in northeastern Arnhem Land and parts of eastern Cape York Peninsula.-3-3. Whereas it is evident that burning traditionally was/is undertaken systematically for a diverse range of purposes, today where burning occurs it often emanates from uncontrolled wildfire; and 4. Importantly for biodiversity conservation, whereas an essential feature of Aboriginal burning was/is that it tended …