Assessment of SPOT 6 imagery for mapping the invasive alien plant species Pinus spp. in a mountainous area of the Western Cape


Remote Sensing

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Aurelia Therese Forsyth, Western Cape Nature Conservation Board (CapeNature), South Africa,
Lesley Anne Gibson, Cape Nature, South Africa ,
Andrew Alexander Turner, Cape Nature, South Africa,


Invasive alien plant (IAP) species pose a major threat to biodiversity in the Western Cape Province. A typical example of an area facing this pressure is the Klein Swartberg mountain where the endangered fauna is particularly threatened. As the clearing of these species is very costly, the mapping of IAP species can assist in understanding the extent of the problem and the costs of clearing.

The use of the Satellite Pour Observation de la Terre 6 (SPOT 6) pan-sharpened images was tested for the mapping of IAP species, in particular Pinus spp. trees, using supervised classification based on decision rules. The study area was burnt in early 2012 and therefore the classification was tested on only a small site (172.4ha) where the trees survived and where some recovery of the natural veld had already occurred. The accuracy assessments performed on the resulting thematic map had an overall accuracy of 84% with a kappa coefficient of 0.68. This finding suggests that mapping Pinus spp. in mountainous areas using the traditional supervised classification is possible using SPOT 6 images.

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