Preliminary assessment of the impacts of invasive alien plants on ecosystem services in South Africa

Abstract

Despite significant advances in the science of invasion ecology, surprisingly little is known about the magnitude of the impacts of invasions. The work described in this paper aims to develop spatially explicit databases of both ecosystem services and invasive alien plant infestations, and to use the two to estimate impacts on each of the services. In this paper our focus is on water resources only. We describe our approach for selecting species and areas in order to estimate current and future potential impacts on water resources. The number of invasive species considered was restricted to those with extensive current or potential distributions; 17 out of a possible 160 species in fynbos shrublands in this case. We estimate that invasive alien plants currently use 16% of the mean annual surface runoff, but that this could rise to over 50% if all available habitat is allowed to become invaded.