Biological Invasions as a Component of South Africa’s Global Change Research Effort

In this chapter, we assess how much research in South Africa has been directed towards biological invasions relative to other elements of global change. Using Web of Science, we systematically reviewed literature relevant to South African ecosystems published between 2000 and 2018 and relating to biological invasions, climate change, overharvesting, habitat change, pollution, and/or atmospheric CO2. We identified 1149 relevant papers that were scored in terms of their coverage of drivers and driver interactions that affect biodiversity or ecosystem services. A strong spatio-temporal effect was observed on research effort. Firstly, effort differed between realms, with habitat change, pollution and overharvesting receiving the largest research focus within terrestrial, freshwater and marine/estuarine realms respectively. Secondly, certain globally well-studied phenomena were not documented in local literature (e.g. there were fewer than five papers on ocean acidification). We identified 21 different interactions between drivers, with the interactions between invasive species and habitat change (for example altered fire regimes in invaded landscapes) being the most prominent. However, fewer than 4% of papers addressed interactions between three or more drivers. This suggests that while the importance of understanding driver interactions is recognised, there has been little in the way of researching the compound effects of driver interactions in South African ecosystems. The long-cited statement that invasive species pose the second-largest threat to biodiversity conservation, behind habitat change, matches the relative research output for this driver in South Africa. Developing a comprehensive quantitative picture of the relative importance of global change drivers will nonetheless be challenging, not only in the unambiguous delineation of drivers, but also due to the unequal availability of research results at comparable spatial and temporal scales. The relative maturity of work on invasive species could provide a basis for exploring such complex interactions and thus contribute to overcoming such barriers.