Response of the Humid Subtropical Grasslands of South Africa to Defoliation
The perennial grasslands of South Africa are inherently extremely mixed but in the subtropical and tropical regions they are characteristically dominated by a relatively small number of species. Hence, the Southern Tall Grassveld of Natal (Veld Type No 64, Acocks 1953) has a species list comprising no fewer than 512 species but in good samples of such veld Themeda triandra (49%) and Apochaete hispida (23%) account for about three-quarters of the veld cover (Foran et al l978). Even in degenerate veld where these species may be relatively unimportant or absent, the veld still tends to be dominated by a relatively small number of species. The Eragrostis and Sporobolus genera often dominate overgrazed areas, Apochaete, Cymbopogon and some species of Hyparrhenia dominate under-utilized areas, and Aristida junciformis may dominate with excessive selective grazing and with complete protection from any form of canopy removal (Foran et al 1978). Hence, in spite of the large number of species which occur in this veld, an understanding of growth responses of a relatively small number of species should definitely assist in the interpretation of the response of the veld as a whole to management. Above all, an understanding of the morphology of development of the tillers of such plants is crucial to an understanding of normal patterns of plant development and to an understanding of the influence of various forms of defoliation on these plants.
KeywordsLeaf Area Index Stem Apex Leaf Removal Leaf Initial Lateral Tiller
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