Ecological thresholds and the status of fire-sensitive vegetation in western Arnhem Land, northern Australia: implications for management
Andrew C. Edwards A B and Jeremy Russell-Smith A B CA Tropical Savannas Management Cooperative Research Centre, PO Box 0909, Charles Darwin University, Darwin, NT 0909, Australia.
B Bushfires NT (Northern Territory Government), PO Box 37346, Winnellie, NT 0821, Australia.
C Corresponding author. Email: jeremy.russell-smith@nt.gov.au
International Journal of Wildland Fire 18(2) 127-146 https://doi.org/10.1071/WF08008
Submitted: 18 January 2008 Accepted: 12 September 2008 Published: 2 April 2009
Abstract
The paper examines the application of the ecological thresholds concept to fire management issues concerning fire-sensitive vegetation types associated with the remote, biodiversity-rich, sandstone Arnhem Plateau, in western Arnhem Land, monsoonal northern Australia. In the absence of detailed assessments of fire regime impacts on component biota such as exist for adjoining Nitmiluk and World Heritage Kakadu National Parks, the paper builds on validated 16-year fire history and vegetation structural mapping products derived principally from Landsat-scale imagery, to apply critical ecological thresholds criteria as defined by fire regime parameters for assessing the status of fire-sensitive habitat and species elements. Assembled data indicate that the 24 000 km2 study region today experiences fire regimes characterised generally by high annual frequencies (mean = 36.6%) of large (>10 km2) fires that occur mostly in the late dry season under severe fire-weather conditions. Collectively, such conditions substantially exceed defined ecological thresholds for significant proportions of fire-sensitive indicator rain forest and heath vegetation types, and the long-lived obligate seeder conifer tree species, Callitris intratropica. Thresholds criteria are recognised as an effective tool for informing ecological fire management in a variety of geographic settings.
Additional keywords: fire regimes, fire-sensitive species, heath, rain forest, satellite imagery, savanna.
Acknowledgements
Cypress survey data were assembled by Felicity Watt, Cameron Yates, Brett Murphy, Brian Lynch (all Bushfires NT), and Ian Munro (Bawinanga Aboriginal Corporation). The present work, undertaken for a over a decade, has been supported by the Natural Heritage Trust and associated community, Northern Territory Government, and Commonwealth Government resources, Bushfires NT, and the Tropical Savannas Management Cooperative Research Centre based at Charles Darwin University, Darwin. It is a pleasure to acknowledge the contributions of many indigenous and non-indigenous colleagues involved in the WALFA project, but especially the inspirational leadership and commitment of Wamud Bardayal Nadjamerrek and Gamerang Peter Cooke.
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