Invasive Alien Plants

Approximately 750 tree species and close to 8 000 shrubby, succulent and herbaceous species are recorded as having been introduced into South Africa. Of these, 161 are regarded as invasive (Van Wilgen et al., 2001; Nyoka, 2003). The majority (approx. 68%) of these invasive alien plants are woody trees and have been the focus of control efforts. The introduction of invasive alien plants in South Africa has led to the conversion of species-rich vegetation to single-species stands of trees. This conversion threatens biodiversity, water security, the productive use of land, and the ecological functioning of natural systems. Invasive alien trees also intensify the impact of fires and floods, increase soil erosion, and have increasingly negative impacts on ecosystem services (De Lange & Van Wilgen, 2010).

The regulations of the National Environmental Management: Biodiversity Act (NEM:BA, 2014) lists invasive alien species which require a range of control measures including removal, permits and appropriate management.  The burden of controlling invasive alien trees is largely being led by the government’s Natural Resource Management (DEA:NRM) programme established in 1995. While the progress and investment is significant, there are notable missed opportunities. However, to date, very little cost recovery has occurred through the sale of various wood products and bioenergy; including timber, wood-fuels, composite wood products, biochar, mulch, compost, and biomass to electricity.