The benefits and costs of clearing invasive alien plants in northern Zululand, South Africa

More than 60% of northern Zululand is tribal land with a substantial area falling within protected areas. Much of the land is invaded by invasive alien plant species (IAPs) such as Chromolaena odorata and Lantana camara. Most of these species do not have any economic value and compromises communal livelihoods and biodiversity. This paper aims to investigate the benefits and costs of clearing IAPs in northern Zululand. A system dynamics model was developed specifically for this analysis. A number of scenarios characterised by various IAP spread rates and clearing investment interventions were formulated and evaluated. The study finds that the highest net returns from clearing the IAPs were generated by value-added products (VAPs), followed by the value of water not consumed by the IAPs. The clearing of IAPs was found to be more cost-effective than augmenting water supply. Supplementing clearing investment operations through private sector co-finance reduces the stock of invasion, increases the area cleared, increases biomass for VAPs, saves more water and clears a greater area for livestock and maize production. The co-finance scenario proved to be the better management option. This scenario generated the most benefits and had a positive net present value (R2.5 million).