Invasive trees are a major problem in South Africa. Many species are well established whereas others are still in the early stages of invasion. The management of invasive species is most cost effective at the early stages of invasion; it is thus essential to target and contain naturalizing invaders before they spread across the landscape. Multi-scale species distribution models (SDMs) provide useful insights to managers; they combine species-occurrence observations with climatic variables to predict potential distributions of alien species. Applying SDMs in human-dominated ecosystems is complicated because many factors associated with human actions interact in complex ways with climatic and edaphic factors to determine the potential suitability of sites for species. The aim of this study was to determine the degree to which a worldwide invader, A. altissima (Simaroubaceae) has occupied its potential range in South Africa, to identify areas at risk of future invasion. To do this we built a set of SDMs at both global and country scales using climatic, land use and human-footprint data. Climatic data best explained the distribution of A. altissima at the global scale whereas variables reflecting human-mediated disturbances were most influential at the national scale. Our analyses show the importance of human-mediated disturbances at a global scale and human occupancy at a country scale in determining the range limits of A. altissima. Populations of this tree species are already present in most parts of South Africa that are environmentally suitable for the species, and management actions need to focus on preventing increases in density in these areas.
Novoa, Ana; Le Roux, J.J. (Johannes Jacobus); Robertson, Mark P.; Wilson, John R.U.; Richardson, D.M. (David Mark), 1958-(Oxford University Press, 2015)
Understanding which species are introduced and become invasive and why are central questions
in invasion science. Comparative studies on model taxa have provided important insights, but
much more needs to be done to ...
Rouget, Mathieu; Robertson, Mark P.; Wilson, John R.U; Hui, Cang; Essl, Franz; Renteria, Jorge; Richardson, David M.(Wiley, 2016-04)
AIM : We develop a framework for quantifying invasions based on lagged trends in invasions
(―invasion debt‖) with the aim of identifying appropriate metrics to quantify delayed
responses at different invasion stages — ...
Wondafrash, Mesfin; Wingfield, Michael J.; Wilson, John R.U.; Hurley, Brett Phillip; Slippers, Bernard; Paap, Trudy(Springer, 2021-06)
Biodiversity and economic losses resulting from invasive plant pests and pathogens are increasing globally. For these impacts and threats to be managed effectively, appropriate methods of surveillance, detection and ...