Savanna Explorer > Arnhem Land > Weeds > At risk from weeds

Weed invasion risks

Floodplains at risk

Gamba grass
Gamba grass has been found in many areas of the Arnhem region Photo: Sam Setterfield 

As in much of northern Australia, floodplain communities are especially at risk from weeds. Large areas of wetlands exhibit rapid species turnover and are thus readily colonised by invasive species. As well as mimosa, the introduced pasture species para grass (Brachiaria mutica) is present and has the potential to degrade large areas of wetland.

Targeted for control

The bauxite mine and associated township of Nhulunbuy are perhaps responsible for most of the disturbed areas in the region. The town area is infested with all major classes of weeds. The main species targeted for control are coffee bush (Leucaena leucocephala) and candle bush (Senna alata), with control work also on African tulip tree (Spathodia campanulata), Singapore daisy (Wedelia trilobata), rubber bush (Calotropis procera) and bellyache bush (Jatropha gossypifolia). In the town lagoon area there are large and expanding populations of Ardisia hujilis, windmill sedge (Cyperus involucratus) and blue pea (Clitorea ternatea), as well as an infestation of salvinia (Salvinia molesta ) in the lagoon itself.

Weeds of concern

Gamba grass (Andropogon gayanus) has been found in many areas of the Arnhem region and is spreading rapidly. Its high fuel loads lead to very hot fires that may irreversibly damage many savanna areas. Coffee bush (Leuceana leucocephala) and gmelina (Gmelina arborea) are naturalising from numerous settlements in the region. Snakeweeds (Stachytarpheta spp.), a morning glory species (Ipomea carnea), parthenium weed (Parthenium hysterophrus), buffel grass (Cenchrus ciliaris) and neem tree (Azadirachta indica ) have all been recorded and are cause for concern.


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