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Uneven distribution of weeds along extensive transects in Australia’s Northern Territory points to management solutions

Authors

  • Noel Preece,

  • Kylie Harvey,

  • Craig Hempel,

  • John C. Z. Woinarski


Noel Preeceis an adjunct research fellow with School for Environmental Research Charles Darwin University, and Principal Ecologist with Biome5 Pty Ltd (PO Box 1200, Atherton, Qld 4883, Australia; Tel: +61 407 996953; Email:noel@biome5.com.au).Kylie Harveyis a Senior Environmental Officer with the Department of Defence, (Coonawarra Base, Berrimah, NT 0828, Australia; Tel: +61 8 8935 4695; Email:kylie.harvey@defence.gov.au).Craig Hempelis a Senior GIS Analyst with the Department of Environment and Resource Management, (Level 10, 400 George St., Brisbane, Qld 4000, Australia; Tel: +61 7 3330 5877; Email:craig.hempel@derm.qld.gov.au).John Woinarskiis Director of Biodiversity with the Northern Territory Department of Natural Resources Environment the Arts and Sport, and an Adjunct Professorial Fellow with Charles Darwin University (PO Box 496, Palmerston, NT 0831, Australia; Tel: +61 8 8995 5001; Email:john.woinarski@nt.gov.au). This paper results from research (about vegetation patterning and the distribution of weeds) for environmental impact assessments for gas pipelines across very extensive remote areas of the Top End of the Northern Territory.

Abstract

Summary  The Top End region of the Northern Territory, Australia, is noted for its relatively unmodified natural state. To gain some insight into the potential for maintaining ecosystem health in this region we undertook a study that assessed the distribution of weeds across very extensive transects. This weed survey was distinct from other studies in that many of the sample sites were distant from tracks or other infrastructure. Twenty-one weed species were recorded along 2000 km of transects. Weeds were reported from 18.7% of the 718 sample points. The incidence of weeds was found to be significantly associated with land tenure, being highest on pastoral lands and peri-urban areas, and very low on Aboriginal lands. The incidence of weeds increased significantly with increasing levels of infrastructure and with increasing proximity to watercourses. There are three main conclusions from this study. First, much of the Top End, particularly remote Aboriginal lands, has exceptionally low levels of weed infestation. Secondly, in such areas, given the relatively small extent of vegetation change through weed invasion, maintenance or re-imposition of traditional fire regimes should be achievable. Thirdly, there is substantial potential for spread of weeds to remote areas, with such spread most likely to occur through increased penetration by infrastructure. Importantly this study indicates that there is still opportunity to prevent widespread weed invasion across the Top End, which is timely given the current Government consideration of the potential for the region to support future agricultural expansion and the fast-paced development of mining, oil and gas resources.

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