Invasive Alien Plants (IAPs) have invaded large areas of South Africa, resulting in numerous negative impacts on indigenous biodiversity and local ecosystems. Besides direct impacts on indigenous species, there are also numerous indirect effects which can impact society.

One of these impacts by woody IAPs (e.g. pine tree species and black wattle) is the reduction in water supply from our mountain catchment regions which serve as freshwater reservoirs for our farms, towns, and cities countrywide. The importance of these mountain catchment regions (and the rivers flowing from them) has become accentuated in recent years when serious droughts have threatened Cape Town and, more recently, the Northern Cape and Gqeberha.

recent study recently highlighted how clearing IAPs in our mountain catchments and riparian (river) areas can boost streamflow by up to 29.5% – the increase in streamflow was particularly evident during drier seasons. For more information on this study, please use the following link to read a summary by the study’s authors.

The SIZA Environmental Standard promotes the management and clearing of IAPs under code requirements 1.12 (There must be evidence of legal compliance for all activities on site that may impact the environment) and 2.5 (Invasive alien plant [IAP] species are controlled).

SIZA members need to 1) be aware of the specific IAP species present on their farm, 2) understand under which category the IAP species fall (according to NEMBA, 2004) and 3) have a suitable IAP control and monitoring plan implemented that prioritises mountain catchment and riparian (river) areas (where relevant) for IAP removal.

For more information on the latest NEMBA Invasive Species Lists in South Africa, please feel free to follow this useful link.