Acacia implexa in South Africa: an emerging invader and potential candidate

Invasive alien plant species have major impacts on biodiversity and ecosystem functioning in most<br> parts of the world. Early detection and rapid response is a crucial part of management programmes.<br> Eradication of invasive species at the early stage of invasion is a very cost-effective intervention, but<br> not all species can be eradicated. This paper reports on a study of Acacia implexa, the screw-pod<br> wattle from Australia, an emerging invader, to determine whether it is a suitable candidate for<br> eradication in South Africa.<br> The species was introduced to South Africa in around 1986. Its current range comprises three<br> populations: in Stellenbosch, Tokai and Wolseley. The populations sizes ranges between 100 and<br> 200ha, with the Tokai population covering the largest area but comprising the fewest plants. The<br> density of the plants ranges from very high to very low, with Stellenbosch (Papegaaiberg) having the<br> highest density. The plants reproduce vegetatively (through suckering and resprouting) and sexually<br> (via seeds). A very high occurrence of suckering was present and few seedlings were observed.<br> Spread is mainly along rivers. Current treatments by area managers are unsuccessful for controlling<br> the species.<br> I consider that eradication of this species is feasible. The eradication plan should place strong<br> emphasis on the effective use of herbicides, communication and cooperation between different<br> managerial organizations, and prioritization of treatment efforts.