The potential range of Ailanthus altissima (tree of heaven) in South Africa: the roles of climate, land use and disturbance
Date
2017Author
Walker, G.A.
Robertson, M.P.
Gaertner, M.
Gallien, L.
Richardson, D.M.
Format Extent
1235663 bytesMetadata
Show full item recordAbstract
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.
Collections
- RESEARCH: Gaertner, M [46]
- RESEARCH: Richardson D [345]
- RESEARCH: Robertson, M [45]
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