Severely degraded rangeland: Implications for plant diversity from a case study in Succulent Karoo, South Africa

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dc.contributor.authorRutherford M.C.
dc.contributor.authorPowrie L.W.
dc.date.accessioned2011-05-15T15:59:29Z
dc.date.available2011-05-15T15:59:29Z
dc.date.issued2010
dc.description.abstractThis study aimed to quantify and understand the impact of severe land degradation on plant diversity in part of the Succulent Karoo. Although total number of species declined with heavy grazing, greater evenness resulted in an increase in species diversity. Annuals and geophytes increased while protective nurse plants were decimated and their dependent beneficiary plant species consequently became locally extinct with heavy grazing. The rich biological soil crust dominated by mosses and liverworts with light grazing gave way to brittle physical-chemical or cyanobacterial crusts after heavy grazing. Although heavy grazing can result in extreme levels of degradation in the context of agricultural rangeland use, the implications for plant diversity per se need not be as severe. There appear to be disturbance-dependent indigenous species which may become locally extinct under good rangeland conditions. Our results support the notion of two different species pools, a grazing resistant pool and a grazing beneficiary pool, where changes in grazing intensity can cause substantial changes in composition and some local extinction of species with little or sometimes even positive change in diversity. Beta diversity across the disturbance contrast substantially raised the gamma diversity and hence landscape species diversity. © 2009 Elsevier Ltd. All rights reserved.
dc.description.versionArticle
dc.identifier.citationJournal of Arid Environments
dc.identifier.citation74
dc.identifier.citation6
dc.identifier.issn1401963
dc.identifier.other10.1016/j.jaridenv.2009.10.013
dc.identifier.urihttp://hdl.handle.net/10019.1/11201
dc.subjectagricultural land
dc.subjectannual plant
dc.subjectcyanobacterium
dc.subjectdiversity index
dc.subjectenvironmental disturbance
dc.subjectgeophyte
dc.subjectgrazing pressure
dc.subjectland degradation
dc.subjectlocal extinction
dc.subjectmoss
dc.subjectnurse plant
dc.subjectphysicochemical property
dc.subjectrangeland
dc.subjectsoil crust
dc.subjectspecies diversity
dc.subjectspecies evenness
dc.subjectspecies pool
dc.subjectSucculent Karoo
dc.subjectBryophyta
dc.subjectCyanobacteria
dc.subjectMarchantiophyta
dc.titleSeverely degraded rangeland: Implications for plant diversity from a case study in Succulent Karoo, South Africa
dc.typeArticle
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