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Weed Management
 
Just like in an average garden, managing weeds in Alcoa's rehabilitated areas is critically important, particularly in ensuring the long-term sustainability of these areas. While there are very few weeds in the native forest, disturbing the soil structure and vegetation during mining and rehabilitation operations can leave some rehabilitated areas vulnerable to weed invasion.
 
Alcoa’s weed management focuses on two types of weeds: Declared weeds and Environmental weeds.
 
Declared weeds are non-native species that have been declared by the Department of Agriculture and Food Western Australia to be potentially noxious weeds. Declared weeds such as the narrow leaf Cotton bush (Gomphocarpus fruiticosus) and inkweed (Phytolacca octandra) can proliferate on our rehabilitated areas. We inspect all our rehabilitated areas for these weeds and when populations are found we spray with an approved herbicide.
 
Environmental weeds are plants that invade, persist and proliferate in natural ecosystems and cause changes in the indigenous biodiversity and ecosystem function of the areas.
 
Prior to 1988, eastern Australian eucalypt and non-indigenous woody understorey species were used in Alcoa’s mine rehabilitation due to concerns about the potential impact of Dieback.  While these species are 'native' Australian plants, they are not indigenous to the northern jarrah forest.  Alcoa is carefully monitoring and managing areas containing these species to ensure that they do not become an issue.
 


Weeds spreading in pit

Click image to enlarge.


Cape weed, an environmental weed, invading young rehabilitation at our Willowdale mine. This area was identified during the 9 month botanical monitoring and was subsequently treated.