Biological Invasions

, Volume 16, Issue 3, pp 691–703 | Cite as

Incorporating risk mapping at multiple spatial scales into eradication management plans

  • Haylee Kaplan
  • Adriaan van Niekerk
  • Johannes J. Le Roux
  • David M. Richardson
  • John R. U. WilsonEmail author
Original Paper


The success of pro-active management of invasive plants depends on the ability to rapidly detect invasive populations and individuals. However, the factors important for detection depend on the spatial scale examined. We propose a protocol for developing risk maps at national, landscape, and local scales to improve detection rates of invasive plant species. We test this approach in the context of developing an eradication plan for the invasive tree Acacia stricta in South Africa. At a national scale we used bioclimatic models coupled with the most likely sites of introduction (i.e. forestry nursery plantations) to identify areas where national-scale surveillance should be focussed. At the landscape and local scales we correlated the presence of A. stricta populations to various attributes. Regional populations were found in forestry plantations only, and mostly on highly used graded roads along which seeds are spread by road maintenance vehicles. Locally, previously recorded plant localities accurately predicted individuals in subsequent surveys. Using these variables, we produced a map of high-risk areas that facilitated targeted searches—which reduced the required search effort by ca. 83 %—and developed recommendations for site-specific surveying. With the high visibility of plants, and relatively small seed banks, long-term annual clearing should achieve eradication. We propose that such multi-scale risk mapping is valuable for prioritising management and surveillance efforts, though caution that the approach is correlative and so it does not represent all the sites that can be invaded.


Biological invasions Early detection Eradication Invasive plant Risk mapping Surveillance Tree invasions 



This project was funded by the DST-NRF Centre of Excellence in Invasion Biology and the Working for Water (WfW) Programme through their collaborative project on “Research for Integrated Management of Invasive Alien Species” and through the WfW funded South African National Biodiversity Institute’s Invasive Species Progamme. DMR acknowledges financial support from the National Research Foundation (Grant 85417), and the Oppenheimer Memorial Trust. We thank Dane Paijmans and Suzaan Kritzinger-Klopper for assistance in the field; Ernita van Wyk for co-ordinating the management meeting; and SANParks and MTO Forestry (Pty) Ltd. for logistical support.

Supplementary material

10530_2013_611_MOESM1_ESM.docx (430 kb)
Supplementary material 1 (DOCX 430 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Haylee Kaplan
    • 1
  • Adriaan van Niekerk
    • 2
  • Johannes J. Le Roux
    • 1
  • David M. Richardson
    • 1
  • John R. U. Wilson
    • 1
    • 3
    Email author
  1. 1.Department of Botany and Zoology, Centre for Invasion BiologyStellenbosch UniversityMatielandSouth Africa
  2. 2.Department of Geography and Environmental Studies, Centre for Geographical AnalysisStellenbosch UniversityMatielandSouth Africa
  3. 3.Invasive Species ProgrammeSouth African National Biodiversity Institute, Kirstenbosch Research CentreClaremontSouth Africa

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