'N Strategie vir die rehabilitasie van versteurde mynbougebiede in suidelike afrika.

Abstract

A literature study revealed that revegetation (grassing) of areas disturbed by mining activities already occurred during the early thirties. Most of the relevant research has been conducted abroad. In the RSA, all the initial work was done on gold mine sand dumps. Although other methods to stabilize the dust generating dumps had also been applied, it was finally agreed upon that a proper vegetation cover is the only permanent solution. During previous years, all initial revegetation attempts were voluntary. During the fifties, law enforcement became ap- plicable in most countries, forcing all mines to revegetate areas disturbed by their activities. In the RSA several laws have already existed since 1956, e.g. the Mines and Works Act (Act 27 of 1956). Although these laws are not directly aimed at revegetation, they can be applied to this aspect. In 1980 the law became more stringent and it became evident that revegetation is not the solution to all problems, due to deterioration of the vegetation occurring on many of the revegetated areas. In order to comply with the demands of the constantly tightening law, research on the rehabilitation of disturbed areas started during 1984. The study area included several mines in the RSA as well as mines situated within the borders of Leboa and Ka Ngwane. The ecological diversity of these localities is stressed by the differences in climate, topo- graphy, geology and vegetation. Some of the mines are 292 situated in areas with an annual rainfall of approximately 400 mm in comparison with others with a precipitation of more than 800 mm. Presently, research on the revegetation of road reserves al- ready indicates that methods and recipes which were success- fully applied in countries with a moderate climate and high rainfall, do not necessarily produce the same results in the RSA with its dry and hot summers. This is one of the main reasons why the use of indigenous grass species was seen as a priority. From the results obtained in experiments on the mine dumps and slimes dams, it was clear that hardy indigenous species were also not capable of solving all the problems. The nega- tive results led to a more holistic approach by which the habitat of plants was taken into consideration. Special attention was given to soil-associated problems at various mines. These problems included aspects such as gradient and length of slopes, particle size of overburden, chemical imbalances of tailings, temperature of tailings, spontaneous combustion, etcetera. Although only a few of the more important factors had been studied, general the results of this research revealed a number of principles which can be applied in devising rehabilitation strategies. The results can also be used as a basis for more detailed studies on the various aspects. The study has shown that every effort should be made to reinstate a situation as near as possible to the natural situation. In order to establish a stable and self-sustaining vegetation on a mine dump, it will be necessary to create a habitat where ecological factors comply with the tolerance limits of the species to be used. This approach implies that 293 the revegetation or grassing alone will not be the answer to the existing problems of recovering disturbed areas, but that complete rehabilitation would be of utmost importance.