The Kakadu landscape change assessment project is an ongoing, multidisciplinary project to assess landscape level changes in riparian, closed forest, and savanna ecosystems in the World Heritage Kakadu National Park, located tropical northern Australia. Like much of northern Australia, the Kakadu landscape is dominated by Eucalyptus savanna with an annual Sorghum grass understory. Climate in Kakadu is driven by a monsoonal pattern. On average, over 90% of the annual rainfall of 1600 mm occurs between the months of November and March. This combination of strong seasonality in precipitation, high lightning activity in the late dry season, and a rapidly regenerating and curing grass understory creates a naturally fire prone environment, with much of the savanna region experiencing fire return intervals of one to two years.

Kakadu National Park, and indeed much of Australia, has been continuously inhabited by hunting and gathering cultures since the middle Pleistocene (c. 40,000 ybp). Aboriginal burning practices follow a calendar based on six seasons. Burning begins soon after the monsoon rains recede and continues throughout the dry season, creating a mosaic pattern that reduces the incidence and severity of late season fires. Although the prehistoric pattern of burning necessarily remains speculative, it is likely that anthropogenic early dry season fires have continuously played a significant role in mitigating the effects of potentially devastating, late dry-season fires started by lightning. It is likely that this anthropogenic fire pattern has enabled the establishment and maintenance of patches of fire-sensitive rainforest vegetation in an otherwise highly fire prone environment.

Although commonly called a “cultural landscape” because of the imprint of fire management by hunting and gathering cultures over millennia, Kakadu has undergone profound management changes in the past century, including the depopulation of the original Aboriginal peoples around the turn of the century, the introduction of buffalo and cattle ranching ventures in the 1950s, and, in recent decades, the attempted re-establishment of Aboriginal fire practices in Kakadu, under the guise of a National Park jointly managed by the Australian National Parks Service and the Aboriginal land owners.

The Kakadu Landscape Change Project will describe the pattern of vegetation change over the past fifty years, and correlate these changes to the management history of the Park. It assesses patterns of change over the past fifty years through the use of digitized aerial photographs overlaid on a GIS platform. Changes to monsoon forest-savanna and riparian forest-savanna boundaries, as well as changes in cover within savannas, are analyzed using a grid-based approach, with the grid remaining spatially static across different time layers. This analysis is combined with interviews of stakeholders who have had a long association with Kakadu about their memories of specific disturbance events, changes in fire management practices, and their knowledge of fire management practices. A model of savanna dynamics will be generated based on individual tree growth data collated from the decade old Kapalga fire experiment combined with contemporary measurements of the fire experiment plots. Thus, this project takes an innovative approach to assessing landscape-level change and the impact of management decisions by combining the techniques of landscape ecology and remote sensing with social scientific and historic techniques to provide a comprehensive picture of the patterns and historical processes of change in Kakadu National Park.

As this project is in its first year, this presentation will introduce the project, as well as the historical and ecological context of Kakadu National Park. Results from the first season of data collection will be presented.