Invasion ecology of the emerging alien plant species in South Africa

Core team member: Thabiso Mokotjomela

Ecology, General | Central University of Technology, Sol Plaatje University, University of Free State | Honours, MSc

Project Background

Biological invasions are a major threat to biodiversity and economy worldwide (Nel et al. 2004; Pimentel et al. 2005; Hulme 2012). South Africa is second most alien plant invaded country to Australia, and consequently has devoted immense effort to managing alien and invasive species (Richardson and van Wilgen 2004; Poona 2008). Different risk analysis tools have been developed aiming to proactively determine potential impacts of invasion for some species and advise on effective management and policy development (Kumschick and Richardson 2013; Wilson et al. 2013; Faulkner et al. 2014; Keller and Kumschick 2017; Kumschick et al. 2018). Despite the efforts to control the widespread invaders in South Africa, many other species are not managed and sometimes their impacts are not reported (van Wilgen and Wilson, 2018) because they are either not yet listed in national legislation as targets for regulation or conflict of interest in their socio-economic use. While the impacts of the major invaders are well known, the emerging invaders together with other unlisted/undetected alien species may compound the problem of invasion in South Africa. There is limited scientific knowledge especially on ecological aspects and life-history traits of many alien plants in South Africa of which precludes accurate categorization of the invasiveness of a species and thus their listing for regulations. Factors influencing the spread rates and establishment success of alien plants should be determined for the accurate prediction of future species invasion risk (Kumschick et al. 2018).

This study therefore aims to collect experimental and observational evidence on life-history traits of alien fleshy-fruited/seed-bearing plant species for supporting the risk analysis processes and accurate listing of species under the current national regulatory framework. In the proposed study, we will also investigate ecological impacts of selected emerging alien species on native habitat as well as their spread and establishment mechanisms. The study will also compare the differences in reproductive biology between invasive and non-invasive home range of each plant species to determine the potential barriers to invasion.