Patterns of plant diversity and their management across South African Rangelands

dc.contributor.advisorBond, William Jen_ZA
dc.contributor.authorUys, Roger Gregoryen_ZA
dc.date.accessioned2014-08-13T14:10:32Z
dc.date.available2014-08-13T14:10:32Z
dc.date.issued2006en_ZA
dc.description.abstractForbs dominate southern Africa's rangeland plant diversity, but have been ignored in favour of grasses that are important for livestock production. To facilitate better conservation management I examined the interaction between patterns of diversity, forb recruitment and disturbance effects across the mesic to semi-arid rangelands east of the escarpment in southern Africa. Results were compared to a well studied North American tallgrass prairie, Konza. Sampled between 1 m2 and 1000 m2 across 25 sites, species and family richness increased with mean annual precipitation up to â2000 m a.s.l., above which cooler temperatures accounted for a decline. Forb functional types ranged from persistent (long-lived, resprouters) in the fire-prone mesic rangelands to more recruiting (short-lived, reseeders) taxa in the drought-prone semi-arid areas. Mesic rangelands should therefore tolerate frequent, low intensity defoliation, and semiarid floras be better suited to infrequent intense disturbances. Seedling recruitment matched richness patterns, primarily increasing with precipitation. Recruitment was highest in the fire treatment at the three mesic sites, but proportionately higher in the animal digging and drought treatments at the three semi-arid sites. Seedling composition differed from the adult sward, suggesting that some species may not recolonise transformed lands. Despite predictions of the Milchunas et al. (1988) and Olff and Ritchie (1998) grazing models, exclusion of large mammalian grazers from 40 m x 40 m plots did not appear to impact forb diversity. Instead, grazing effects sampled in 100 x 1m' quadrats per treatment, across ten sites, were overridden by the mesic to semi-arid gradient along which the sites were orientated. Species richness declined under heavy communal cattle grazing along fence-line contrasts at two mesic sites, with soft-leaved monocot (orbs being replaced by short-lived divot weeds not found inside the adjacent lightly grazed nature reserves. Marked differences in the diversity and disturbance responses of tallgrass prairie and southern African rangelands suggest that management strategies cannot be extrapolated from similar ecosystems around the world.en_ZA
dc.identifier.apacitationUys, R. G. (2006). <i>Patterns of plant diversity and their management across South African Rangelands</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/6200en_ZA
dc.identifier.chicagocitationUys, Roger Gregory. <i>"Patterns of plant diversity and their management across South African Rangelands."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2006. http://hdl.handle.net/11427/6200en_ZA
dc.identifier.citationUys, R. 2006. Patterns of plant diversity and their management across South African Rangelands. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Uys, Roger Gregory AB - Forbs dominate southern Africa's rangeland plant diversity, but have been ignored in favour of grasses that are important for livestock production. To facilitate better conservation management I examined the interaction between patterns of diversity, forb recruitment and disturbance effects across the mesic to semi-arid rangelands east of the escarpment in southern Africa. Results were compared to a well studied North American tallgrass prairie, Konza. Sampled between 1 m2 and 1000 m2 across 25 sites, species and family richness increased with mean annual precipitation up to â2000 m a.s.l., above which cooler temperatures accounted for a decline. Forb functional types ranged from persistent (long-lived, resprouters) in the fire-prone mesic rangelands to more recruiting (short-lived, reseeders) taxa in the drought-prone semi-arid areas. Mesic rangelands should therefore tolerate frequent, low intensity defoliation, and semiarid floras be better suited to infrequent intense disturbances. Seedling recruitment matched richness patterns, primarily increasing with precipitation. Recruitment was highest in the fire treatment at the three mesic sites, but proportionately higher in the animal digging and drought treatments at the three semi-arid sites. Seedling composition differed from the adult sward, suggesting that some species may not recolonise transformed lands. Despite predictions of the Milchunas et al. (1988) and Olff and Ritchie (1998) grazing models, exclusion of large mammalian grazers from 40 m x 40 m plots did not appear to impact forb diversity. Instead, grazing effects sampled in 100 x 1m' quadrats per treatment, across ten sites, were overridden by the mesic to semi-arid gradient along which the sites were orientated. Species richness declined under heavy communal cattle grazing along fence-line contrasts at two mesic sites, with soft-leaved monocot (orbs being replaced by short-lived divot weeds not found inside the adjacent lightly grazed nature reserves. Marked differences in the diversity and disturbance responses of tallgrass prairie and southern African rangelands suggest that management strategies cannot be extrapolated from similar ecosystems around the world. DA - 2006 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2006 T1 - Patterns of plant diversity and their management across South African Rangelands TI - Patterns of plant diversity and their management across South African Rangelands UR - http://hdl.handle.net/11427/6200 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/6200
dc.identifier.vancouvercitationUys RG. Patterns of plant diversity and their management across South African Rangelands. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2006 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/6200en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherBotanyen_ZA
dc.titlePatterns of plant diversity and their management across South African Rangelandsen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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