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HERBIVORE-DRIVEN LAND DEGRADATION: CONSEQUENCES FOR PLANT DIVERSITY AND SOIL IN ARID SUBTROPICAL THICKET IN SOUTH-EASTERN AFRICA

2012; Wiley; Volume: 25; Issue: 6 Linguagem: Inglês

10.1002/ldr.2181

1099-145X

M. C. Rutherford, Leslie W. Powrie, Lara B. Husted,

Agroforestry and silvopastoral systems

Land Degradation & DevelopmentVolume 25, Issue 6 p. 541-553 Research Article HERBIVORE-DRIVEN LAND DEGRADATION: CONSEQUENCES FOR PLANT DIVERSITY AND SOIL IN ARID SUBTROPICAL THICKET IN SOUTH-EASTERN AFRICA M. C. Rutherford, Corresponding Author M. C. Rutherford Applied Biodiversity Research Division, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735 South Africa Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa Correspondence to: M. C. Rutherford, Applied Biodiversity Research Division, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735, South Africa. E-mail: [email protected]; [email protected]Search for more papers by this authorL. W. Powrie, L. W. Powrie Applied Biodiversity Research Division, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735 South AfricaSearch for more papers by this authorL. B. Husted, L. B. Husted Applied Biodiversity Research Division, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735 South AfricaSearch for more papers by this author M. C. Rutherford, Corresponding Author M. C. Rutherford Applied Biodiversity Research Division, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735 South Africa Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa Correspondence to: M. C. Rutherford, Applied Biodiversity Research Division, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735, South Africa. E-mail: [email protected]; [email protected]Search for more papers by this authorL. W. Powrie, L. W. Powrie Applied Biodiversity Research Division, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735 South AfricaSearch for more papers by this authorL. B. Husted, L. B. Husted Applied Biodiversity Research Division, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Claremont, 7735 South AfricaSearch for more papers by this author First published: 05 July 2012 https://doi.org/10.1002/ldr.2181Citations: 30Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL ABSTRACT Investigations were made of plant and soil responses to severe degradation through heavy grazing and browsing in arid, succulent, subtropical thicket. Severe degradation of thicket is of major concern in terms of threatened biodiversity, unsustainable utilization and collapse of other ecosystem services. We used a natural, field contrast, case-study approach, sampling within plots under lightly and heavily stocked conditions. Mean plant species diversity and richness did not change significantly at sample plot level although there was a 27 per cent decline in richness with degradation at the scale of the study site. On degraded plots, there was a high species turnover and high beta diversity, which created a replacement zone rather than an impoverished zone. Replacement species were confirmed as mainly, but not exclusively, weedy annual grasses and alien forbs. The few persisting perennials were small trees that survived above the browse line, and hardy shrub species. Perennial persisting and replacement species below the browse line may suggest potential candidates for restoration. Nitrogen was the only measured nutrient that showed a significant decrease with degradation. Phosphorous, potassium and magnesium increased significantly, with the first two mentioned reaching potentially excessive levels. Soil salinization occurred with an order of magnitude increase in sodium. Thus, the increased cation exchange capacity occurred together with development of a nutrient imbalance. The elevation in some nutrients and soluble salts is ascribed to wind-determined directional grazing that concentrate livestock in the degraded area. The implications of the above altered soil conditions for thicket restoration need to be further explored. Copyright © 2012 John Wiley & Sons, Ltd. REFERENCES Ano AO, Ubochi CI. 2007. Neutralization of soil acidity by animal manures: mechanism of reaction. African Journal of Biotechnology 6: 364– 368. Atkinson IAE. 1997. Problem weeds on New Zealand islands. Science for Conservation 45: 1– 156. 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