| Patterns of seed production and shrub association in two palatable Karoo shrub species under contrasting land use intensities | |
Abstract/OtherAbstract
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Seed production and shrub association patterns of the twopalatable shrubs. <i>Tripteris sinuatum</i> and <i>Tetragoma froticosa</i> were investigated on heavily grazed communal and lightly grazed commercial rangeland in the succulent karoo. Namaqualand. Seed production in both these species was substantially reduced on the communal rangeland relative to the commercial rangeland. Seed production in <i>T. sinuatum</i> was most severely affected. with seed production on the communal rangeland two orders of magnitude lower than on the commercial rangeland. The proportion of <i>T. sinuatum</i> and <i>T. froticosa</i> shrubs growing unassociated with other shrubs on the communal rangeland was reduced by approximately 50%. <i>Lycium ferocissimum</i> was most effective as a refuge plant for <i>T. sinuatum</i> in terms of the mean seed production per plant. <i>Ruschia robusta</i> was however most important in terms of the overall amount of seed produced by <i>T. sinuatum</i> and <i>T. froticosa</i> on the communal rangeland. due to the large number of times this association occurred. Refuge plants did not appear to be particularly important for <i>T. froticosa</i> in terms of seed production, but were important in terms of providing safe sites for recruitment. The results of this study suggest that unpalatable or thorny species such as <i>L. ferocissimum</i> play an important role inproviding refuge sites for palatable species that might otherwise become entirely lost from overgrazed rangelands. <i>African Journal of Range & Forage Science</i> 17(1, 2&3): 22-26 |
Authors
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Todd, SW; National Botanical Institute, Private Bag X7, Claremont, 7735 Republic of South Africa; todd@nbict.nbi.ac.za |
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Contributors
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Publication Detail
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Publisher : African Journal of Range and Forage Science Association of Crop Science, Uganda Type : Peer-Reviewed Article, Format : - |
Date Detail
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2007-05-04 |
Subject
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- , associational refuge; communal rangelands; herbivory; overgrazing; rangeland dynamics |
Coverage
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; ; |
Relation
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- |
Source
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African Journal of Range and Forage Science - African Journal of Range and Forage Science; Vol. 17 (2000) |
Copyright Information
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Copyright for articles published in this journal is retained by the journal. |
Other Details
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Languages : en |
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