A study of the interactions between C₃ and C₄ grasses on Signal Hill, Cape Town

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dc.contributor.advisorBond, William Jen_ZA
dc.contributor.advisorMoll, Eugene Jen_ZA
dc.contributor.authorLigavha, Maanda Solomonen_ZA
dc.date.accessioned2016-09-28T19:08:35Z
dc.date.available2016-09-28T19:08:35Z
dc.date.issued1990en_ZA
dc.descriptionBibliography: pages 116-141.en_ZA
dc.description.abstractCurrent concerns with reference to global climate change can help us to focus on the competitive interaction of grasses with different photosynthetic pathways. The dominance of eight different common grass species occurring on Signal Hill was investigated, and three species which occurred in localized dense stands were suitable for detailed investigation. Distribution patterns of the three selected grass species, Hyparrhenia hirta (L.) Stapf (C₄), Merxmuellera disticha (Nees) Conert (C₃) and Themeda triandra Forsskal (C₄) were interpreted using a dispersion index (R). Regularity in dispersion of individual grasses was quite common, whilst aggregated and random dispersion was not. Potential competitive interactions between those grasses (perennial) on the east- and west-facing slopes of Signal Hill ·were then described. Using nearest-neighbour analysis it was possible to show that both inter- and intra-specific competition was occurring between the grass species investigated. Pattern analysis was supported by removal experiments and it was possible to infer that the three grass species are competing for water and space. The measurements of carbon dioxide fixation rates under greenhouse conditions demonstrated that C₄ grasses were more competitive, relative to C₃ grass and responded more strongly to changes in soil moisture status. Species with the C₄ pathway showed substantial increase in photosynthetic rate in response to an increase in soil moisture content whilst a C₃ grass' carbon dioxide assimilation rate at those moisture content was relatively lower. Seedling transplant experiments showed that monospecificity of patches could chiefly be attributed to familial clumping, limited seed dispersal, and vegetative reproduction. Phenological aspects like growth, production, and reproduction in terms of flowering tillers of neighboured and non-neighboured individuals, and of individuals one year and two years after fire, were studied to assess the importance of competitive interactions and fire. The results of this study posed the following question: In the light of the global warming effect, which grass species (representing C₃ and C₄ pathways) are likely to prevail in different parts of the world?en_ZA
dc.identifier.apacitationLigavha, M. S. (1990). <i>A study of the interactions between C₃ and C₄ grasses on Signal Hill, Cape Town</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/21997en_ZA
dc.identifier.chicagocitationLigavha, Maanda Solomon. <i>"A study of the interactions between C₃ and C₄ grasses on Signal Hill, Cape Town."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1990. http://hdl.handle.net/11427/21997en_ZA
dc.identifier.citationLigavha, M. 1990. A study of the interactions between C₃ and C₄ grasses on Signal Hill, Cape Town. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Ligavha, Maanda Solomon AB - Current concerns with reference to global climate change can help us to focus on the competitive interaction of grasses with different photosynthetic pathways. The dominance of eight different common grass species occurring on Signal Hill was investigated, and three species which occurred in localized dense stands were suitable for detailed investigation. Distribution patterns of the three selected grass species, Hyparrhenia hirta (L.) Stapf (C₄), Merxmuellera disticha (Nees) Conert (C₃) and Themeda triandra Forsskal (C₄) were interpreted using a dispersion index (R). Regularity in dispersion of individual grasses was quite common, whilst aggregated and random dispersion was not. Potential competitive interactions between those grasses (perennial) on the east- and west-facing slopes of Signal Hill ·were then described. Using nearest-neighbour analysis it was possible to show that both inter- and intra-specific competition was occurring between the grass species investigated. Pattern analysis was supported by removal experiments and it was possible to infer that the three grass species are competing for water and space. The measurements of carbon dioxide fixation rates under greenhouse conditions demonstrated that C₄ grasses were more competitive, relative to C₃ grass and responded more strongly to changes in soil moisture status. Species with the C₄ pathway showed substantial increase in photosynthetic rate in response to an increase in soil moisture content whilst a C₃ grass' carbon dioxide assimilation rate at those moisture content was relatively lower. Seedling transplant experiments showed that monospecificity of patches could chiefly be attributed to familial clumping, limited seed dispersal, and vegetative reproduction. Phenological aspects like growth, production, and reproduction in terms of flowering tillers of neighboured and non-neighboured individuals, and of individuals one year and two years after fire, were studied to assess the importance of competitive interactions and fire. The results of this study posed the following question: In the light of the global warming effect, which grass species (representing C₃ and C₄ pathways) are likely to prevail in different parts of the world? DA - 1990 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1990 T1 - A study of the interactions between C₃ and C₄ grasses on Signal Hill, Cape Town TI - A study of the interactions between C₃ and C₄ grasses on Signal Hill, Cape Town UR - http://hdl.handle.net/11427/21997 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/21997
dc.identifier.vancouvercitationLigavha MS. A study of the interactions between C₃ and C₄ grasses on Signal Hill, Cape Town. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1990 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/21997en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherBotanyen_ZA
dc.titleA study of the interactions between C₃ and C₄ grasses on Signal Hill, Cape Townen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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