Fire ecology and Aboriginal land management in central Arnhem Land, northern Australia: a tradition of ecosystem management

Aim To compare fire behaviour and fire management practice at a site managed continuously by traditional Aboriginal owners with other sites in tropical northern Australia, including the nearby Kakadu National Park, and relate those observations to indicators of landscape condition. Location Dukaladjarranj, a clan estate in north-central Arnhem Land, in the seasonal tropics of northern Australia. The site abuts a vast sandstone plateau that is an internationally recognized cent re of plant and animal biodiversity. Methods Ecological assessments included: (1) mapping of the resource base of the estate from both traditional and ecological perspectives; (2) aerial survey of the extent of burning, distribution of the fire-sensitive native pine Callitris intratropica, rock habitats, and a range of macropod and other fauna resources; (3) fauna inventory; (4) detailed ecological assessment of the status of fire-sensitive vegetation; and (5) empirical assessment of the intensities of experimental fires. Ethnographic information concerning traditional fire management practice was documented in interviews with senior custodians. Results Experimental fires lit during the study were of low intensity compared with late dry season fires reported elsewhere, despite weather conditions favouring rapid combustion. In contrast to other parts of the savanna, fuel loads comprised mostly leaf litter and little grass. We found that (i) a large proportion of the estate had been burned during the year of the study (ii) burned sires attracted important animal food resources such as large macropods (iii) important plant foods remained abundant (iv) well represented in the landscape were fire sensitive vegetation types (e.g. Callitris intratropica Baker & Smith woodlands) and slow growing sandstone 'heath' typically dominated by myrtaceaous and proteaceous shrubs (v) diversity of vertebrate fauna was high, including rare or range-restricted species (vi) exotic plants were all but absent. Traditional practice includes regular, smaller fires, lit throughout the year, and cooperation with neighbouring clans in planning and implementing burning regimes. Main conclusions We attribute the ecological integrity of the site to continued human occupation and maintenance of traditional fire management practice, which suppresses otherwise abundant annual grasses (Sorghum spp.) and limits accumulation of fuels in perennial grasses (Triodia spp.) or other litter. Suppression of fuels and coordination of fire use combine to greatly reduce wildfire risk and to produce and maintain diverse habitats. Aboriginal people derive clear economic benefits from this style of management, as evidenced by abundant and diverse animal and plant foods. However, the motives for the Aboriginal management system are complex and include the fulfillment of social and religious needs, a factor that remains important to Aboriginal people despite the rapid and ongoing transformation of their traditional lifestyles. The implication of this study is that the maintenance of the biodiversity of the Arnhem Land plateau requires intensive, skilled management that can be best achieved by developing co-operative programmes with local indigenous communities.