ABSTRACT
South Africa’s natural resources are being degraded at an alarming rate. Soil erosion, as a consequence of overgrazing and improper cultivation, is considered to be one of the most serious environmental problems facing South Africa. To enable effective natural resource auditing and monitoring, spatial data on the conservation status of natural resources are required at district, provincial, and national scales. This paper presents an overview of the rationale and preliminary results of developing a system to map and monitor the conservation status of natural vegetation and soils in Mpumalanga Province, by means of remote sensing and geographic information system (GIS) technology, at a 1:250,000 scale. The monitoring system requires systematic and repeatable activities designed to measure changes in natural resources through space and time. Monitoring of natural vegetation involves: (1) compiling a natural stratification map; (2) deriving land cover data using Landsat TM imagery; (3) quantifying transformation of natural vegetation by various land uses; (4) mapping the condition of natural vegetation with the aid of historical NOAA data (13 years) and current Landsat TM imagery; (5) mapping areas currently subjected to alien vegetation infestation and bush encroachment; and (6) spatial modelling (GIS) to map areas susceptible to various forms of degradation. Monitoring the conservation status of soils involves: (1) mapping various classes of eroded or degraded areas with Landsat data using a Bare Soil Index (BSI); and (2) spatial modelling (GIS) of predicted water erosion and the susceptibility of soils to water erosion.
