WfW Planning

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Assessment

Problem: 
 
“Currently the main limitation to designing a control strategy is the lack of comprehensive mapping of aliens at national, regional and quaternary scales. Until spatial information covers the full extent of South Africa it will not be possible to evaluate completely whether the programme is indeed focussing on the most important areas from a species perspective. This broader-scale mapping was identified as an important tool by many of the area managers during regional visits.” – WfW External Evaluation (2003)
 
 
Solutions:
  • Rowlinson et al. (1999) compared remote sensing data sources and techniques for identifying and classifying alien invasive vegetation in riparian zones.
  • Stow et al. (2000) investigated the potential of airborne colour-infrared digital camera imagery for inventory and mapping of alien plant invasions in fynbos.
  • Le Maitre et al. (2000) conducted a preliminary assessment of the impact of invading alien plants on surface water resources
  • Gibson & Low (2003) conducted a survey and audit of available data sets of invading alien plant distribution.
  • Hulme (2003) recommended the repeat sampling of specific points across large geographic areas for monitoring invasions and targeting management.
  • Rouget et al. (2004) assessed the climatic correlates of distribution of 71 important invasive alien plants, and analysed the implications of these findings for future invasions in different vegetation types in South Africa, Lesotho and Swaziland over the next few decades.
  • Cochran (2005) investigated the effectiveness of airborne colour-infrared imagery as a medium for mapping alien vegetation
  • Cobbing (2006) investigated the use of LANDSAT ETM imagery as a suitable data capture source for alien invasive Acacia spp.
  • McNaught et al. (2006) developed a field manual for surveying and mapping invasive alien plants.
  • Henderson (2007) provided an overview of the species identity, invasion status, geographical extent, and abundance of alien plants based on field records from 1979 to 2000
  • Van Wilgen et al. (2008) conducted a biome-scale assessment of the impact of invasive alien plants on ecosystem services.
  • De Lange & Van Wilgen (2010) found that although an estimated R6.5 billion was lost every year due to invading alien plants, this would have amounted to an estimated additional R41.7 billion had no control been carried out.
  • Foxcroft et al. (2009) found the selection of the appropriate scale of resolution to be crucial when evaluating the distribution and abundance of alien plant invasions, understanding ecological processes, and operationalizing management applications and monitoring strategies.
  • Poona & Shezi (2010) investigated the use of different satellite remote sensors and techniques to identify, map, monitor and predict the spread and distribution of some of the major current and emerging invasive alien plant species in the KwaZulu-Natal province.
  • Henderson (2010) added a further 13,000 records and 106 species to the Southern African Plant Invaders Atlas (SAPIA) and made it accessible to the broad public via www.agis.agric.za/wip.
  • Van den Berg (2010) investigated the detection, quantification and monitoring of Prosopis spp. in the Northern Cape province using remote sensing and GIS.
  • Kotze et al. (2010) established and implemented a cost effective, objective and statistically sound invasive alien plant monitoring system at a quaternary catchment level (GIS grid data, summaries & wall maps).
  • Van Wilgen et al. (2012) assessed the effectiveness of the Working for Water programme over the past 15 years, by reviewing data from three national-level estimates of the extent of invasion, records of the costs and spatial extent of invasive species control operations, assessments of the effectiveness of biological control, and smaller-scale studies.