Weeds in Arnhem Land

Regional profile

The Arnhem region is one of the least disturbed areas in Australia, and also includes a major portion of the Northern Territory's coastline. It is unique in being virtually all under Aboriginal ownership. However, since European settlement much of the country has been depopulated, with consequent changes in fire regimes. Roads, mines, townships and communities have disturbed small areas of the landscape. Other areas have also been modified by use as cattle stations.

Weed threats

Within the Arnhem region, little is known about the weed status of most areas outside the major settlements. However, it does appear that the region is currently one of the least weedy in the world. Generally weeds are concentrated in disturbed areas around townships, communities and outstations, although weed populations are also increasing in areas such as the Arafura wetlands in north-east Arnhem Land. Weed populations in much of the Arnhem region are likely to increase rapidly without effective involvement of local communities in weed management programs.

Mimosa spread

A notable example of how weed problems can quickly develop in such a region was the severe mimosa infestation that developed on the Oenpelli floodplain in the 1980s. Some control was undertaken late in 1980s, but a concerted effort was not made until the 1990s when 8000 hectares of floodplain were infested. An $8 million, Commonwealth-funded program has reduced the extent of the infestation, but it remains a major problem. Given the many isolated occurrences of mimosa in the region, the potential remains for further spread unless there is sustained effort in controlling existing populations and rapid identification and eradication of satellite outbreaks.

These issues are discussed in Smith, N. (2001). Unwanted Exotic Plants on Northern Land Council Lands, Northern Territory, Australia. Tropical Savannas CRC, Darwin.  Click on the link below to find out more.