Veldtipes, Verspreiding Van Die Groter Soogdiere, En Enkele Aspekte Van Die Ekologie Van Kaokoland
Initiated in 1975, the purpose of this study was to obtain basic ecological information needed for the conservation, management and utilization of the fauna and flora of Kaokoland, S.W.A. Accordingly the vegetation of the area was classified into veldtypes and the status, distribution and movements of the bigger mammals were determined. To assist in the description of veld types, quantitative classification of the vegetation was based on the variable quadrant plqt method for trees and shrubs and the steppoint method for herbs. Information thus gathered was used to determine species composition and to estimate density per hectare, mean height, mean crown diameter, mean stem diameter, mean number of stems and canopy cover for the different plant species. In conjunction with bioclimatic and geographical divisions the above mentioned quantitative information of the vegetation resulted in the description of homogeneous vegetation units. In this way the vegetation was separated into fourteen veld types. The location, boundaries, topography, geology, soil, treestratum, shrubstratum, herbstratum for each veldtype and the major plant communities within each are described. In addition the vegetation of the drainage lines and the plants associated with springs are described. A synopsis of previous descriptions and classifications is also presented. It was found that the vegetation of Kaokoland ranges from a subtropical savanna with a maximum density of 2 085 trees and shrubs per hectare in the east to a nearly vegetationless desert with less than one shrub per hectare in the west. This gradient from east to west coincides with the gradient for rainfall. Some of the plant species occurring in each of the bioclimatic regions are specific for that region and ecologically adapted to it. Information on the bigger mammals was obtained through ground and aerial surveys conducted on a seasonal basis. Information collected included locality, numbers, habitat, distance from open water, group size and when possible also group structure, feeding and behaviour. This information was used to quantify the distribution and status of 36 species of bigger mammals. Social structure, habitat preference, movement and seasonal changes of the separate parameters were determined for the more common and easily observed mammals. Group structure, sex ratios, reproduction and feeding of some species are briefly discussed. Of the 36 mammal types studied, 21 are regarded as common, 6 as rare but in no immediate danger of extinction, the status of 3 as unknown, and 6 are regarded as highly endangered. The endangered types are Diceros bicornis, Aepyceros melampus petersi, Sylvicapra grimmia, Hippopotamus amphibius, Panthera leo and Lycaon pictus. Of these, two seem to be already extinct, i.e. Hippopotamus amphibius and Lycaon pictus. Because the different aerial surveys differ in time and space it was impossible to determine trends in game numbers. The results of the aerial surveys range from 2 256 bigger m~mals in the dry season to 8 006 in the rainy season. Therefore information on the past and present distribution of the various ma;nmals are used as indicators of trends. With the exception of single smaller antelope and predators, all bigger mammals show a decline in their range of distribution since 1970.