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CR 17:195-208 (2001)
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Abstract
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Effects of rainfall variability and communal and semi-commercial grazing on land cover in southern African rangelands
Opha P. Dube1,*, Geoff Pickup2
1Department of Environmental Science, University of Botswana, Private Bag UB 00704, Botswana
2CSIRO Land and Water, PO Box 1666, Canberra City ACT 2601, Australia
*E-mail: dubeop@mopipi.ub.bw
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ABSTRACT: Semi-arid ecosystems in southern Africa are experiencing change due to natural variability in rainfall and to changes in the type and intensity of land use. This paper applies grazing gradient techniques to vegetation cover dynamics in areas of
communal and semi-commercial grazing in the Kalahari rangelands of Botswana to see whether human impact can be separated from that of climate variability. Landsat Thematic Mapper and Multispectral Scanner data were acquired for the Gumare and Hainaveld
areas for a number of wet and dry seasons. Vegetation cover was mapped using the PD54 vegetation index. Gradients in both vegetation cover and vegetation response to rainfall were identified under communal use, suggesting both human impact and
human-induced degradation. However, patterns were complex because of multiple focal points in the hinterland of larger settlements. Gradients in vegetation response were more effective than gradients in cover as identifiers of human impact in
semi-commercial grazing areas. These gradients intensify in dry periods but vegetation partially recovers after good rains. Over time, however, the gradients are intensifying, suggesting that long-term grazing impact is occurring. As gradients intensify
and degradation increases, vulnerability of grazing systems to rainfall variability and to drought is likely to intensify.
KEY WORDS: Rainfall variability · Grazing gradients ·Remote sensing · Vegetation cover
Full text in pdf format
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Published in CR Vol.
17, No. 2
(2001) on August 15
Print ISSN: 0936-577X; Online ISSN: 1616-1572.
Copyright © Inter-Research, Oldendorf/Luhe, 2001
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