Vegetation and Geomorphology in Northern Rhodesia

The vegetation of Central Africa has been mapped and described by a number of authors. Their works fall into two categories, those concerned with the major vegetation formations in broad outline over large areas and those detailing the indi? vidual vegetation types within these formations over smaller areas. Important works include those of Shantz and Marbut (1923), Scaetta (1937), Aubreville (1949) and Keay (1959) on a continental or broad regional basis. In the second category Trapnell has described the vegetation over the greater part of Northern Rhodesia (1937, 1943, 1950). Henkel (1931) has outlined the picture in Southern Rhodesia, where Gilliland (1938), Crook (1956), Goldthorpe (1957) and Wild (1952, 1955, 1956) have described certain areas in greater detail. Gossweiler and Mendonca have provided a description of Angola, Mozambique is depicted in the Atlas de Portugal Ultramarino. In the Congo, Lhoas (1957) has written on the Katanga, and Devred (1954, 1958) on the Mvuazi and Kwango districts. These writers give detailed accounts of the composition of the major vegetation formations and of the several vegetation types which they recognize within them. Most of them relate the distribution of these types to the prevailing climatie conditions, and stress the importance of fire and deliberate burning in bringing about the present widespread occurrence of savanna and restricted occurrence of rain forest; some invoke both climatie change and fire to explain certain anomalies of distribution. Others describe the soil and drainage conditions, and Henkel remarks on the inability of forest trees to become established in areas subject to periodic waterlogging. Another, Trapnell, in his publications on Northern Rhodesia, giving due weight to climatie influences, stresses the close association between vegetation and soil, and even suggests that 'physiographic factors are perhaps of the greatest importance in determining the distribution of soil and vegetation types.' Here, however, he is concerned primarily with the coincidence of physiographic regions and climatie regimes and, although he associates the Brachystegia-Isoberlinia woodlands and the soils characterized by a layer of iron concretions or laterite with the extensive level plateau, he makes no attempt to explain this relationship. The views of the various writers on the African vegetation, taken either separately or in combination, fail to explain satisfactorily either the present distribution of forest and savanna or that of the many vegetation associations included within them. These writers apparently have not acknowledged the ever-changing composition of vegetation, the constant struggle of individual species to extend their range and the way in which slight changes in the physical environment may favour some species at the expense of others. They have failed to appreciate that geomorphological pro? cesses, themselves governed partly by the prevailing climate, are continuously modifying the relief and drainage, the soils and the micro-climate, thereby creating conditions more favourable for some plants and less favourable for others, and bring? ing about the extension of some vegetation associations and the recession of others of which only relicts may remain. In this paper the importance of the climatie, edaphic and biotic influences will be accepted and attention focused on the

Agroforestry · Biology · Distribution (mathematics · Geography · Geomorphology · Habitat · Physical geography · Vegetation (pathology · Vegetation types · African Botany and Ecology Studies · Ecology · Environmental Science · Geology · Mediterranean and Iberian flora and fauna · Plant Diversity and Evolution

• Symbols, not data

  Open Access•Chris S Duvall•Geographical Journal•2003

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• Savanna and Forest in Western Nigeria

  Open Access•W B Morgan, R P Mo et al.•Africa•1965

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