Multitemporal Landsat TM imagery analysis for mapping and quantifying degraded rangeland in the Bahurutshe communal grazing lands, South Africa

Multitemporal remote sensing was used to map and quantify rangeland degradation in communal grazing lands of Lehurutshe district, northwestern South Africa. Based on established theory that veldt degradation ultimately results in bare land in addition to loss and replacement of palatable rangeland species, rangeland bare land was used as an indicator of degradation, primarily due to lack of palatable rangeland species spectral signatures. Using a January 1989 image as the base year, in which the rangelands were healthier, January 1995 and 2005 Landsat Thematic Mapper (TM) images were used for mapping and quantifying degradation, with the hypothesized degradation status that bare land in the rangelands would not have emerging grass just after the start of the summer rains. Image processing involved geometric registration, hybrid classification and geographic information system (GIS) overlay analysis. The results indicate moderate rangeland degradation, up to 4% area, particularly in the district's more inhabited south. Although the amount of degradation is moderate, the degradation has significant localized effects in this semiarid environment. Remote sensing techniques appear vital for rapid rangeland and other multitemporal spatial analyses in the area and the southern Africa subregion in general, to be taken advantage of with the launch of South Africa's environmental satellite.