Impacts of Acacia saligna on soil characteristics can persist up to 10 years
It is often thought that following the control and removal of an invasive alien plant that its impacts will quickly diminish. However, it is becoming more evident that some invasive plants leave long lasting impacts after their removal. Acacia saligna (Fabaceae) is native to Australia and has been recorded as an invasive species in a number of regions including the EPPO region (e.g. Cyprus, Portugal and Israel), South Africa and South America. The present study collected soil from invaded, non-invaded and previously managed areas (sites where A. saligna had been cleared 2, 6 and 10 years ago). The soil was analyzed for pH levels, carbon, nitrogen, available phosphorus, ammonium and nitrates. A. saligna invasion alters overall soil characteristics but specifically raises pH by 0.6 – 1.8. Soil characteristics (e.g. pH) were not restored to the natural conditions after control highlighting that soil effects persist up to 10 years following clearing. Furthermore, A. saligna control elevates soil nitrate levels and these can remain higher in invaded sites (1.55-6.67 mg per kg) compared to non-invaded (2.16-4.35 mg per kg) sites, up to 10 years post clearing. Elevated nitrate levels often facilitate secondary invasion which may further act to hinder restoration attempts.
Nsikani MM, Novoa A, van Wilgen BW, Keet JH, Gaertner M (2017) Acacia saligna’s soil legacy effects persist up to 10 years after clearing: Implications for ecological restoration. Austral Ecology. DOI: 10.1111/aec.12515.