The influence of rainfall variability on savanna tree seedling establishment

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dc.contributor.advisorBond, William Jen_ZA
dc.contributor.advisorFebruary, Edmund Cen_ZA
dc.contributor.authorBotha, Susanen_ZA
dc.date.accessioned2014-08-13T14:17:03Z
dc.date.available2014-08-13T14:17:03Z
dc.date.issued2006en_ZA
dc.descriptionIncludes bibliographical references (leaves 111-114).en_ZA
dc.description.abstractMy thesis investigates the rainfall requirements necessary for tree seedling survival of different savanna species in the first year of growth. Results from a field drought experiment showed that dry season survival for seedlings of Acacia nigrescens and Philenaptera vialacea was not related to wet season length. Instead mortality was highest immediately after germination despite irrigation to minimize dry spells. Furthermore there was no relationship between seedling size and the length of the dry spell seedlings of Acacia nigrescens and Philenaptera vialacea grown in basalt clay in the greenhouse, could survive. This was in contrast to seedlings of Scleracarya birrea and Terminalia sericea grown in granite sand, where number of dry days survived increased with number of growth days received. There was no significant differences in rainfall variability (t-test: tL III = 1.56, P = 0.121, F-ratio = 1.13) between a semi-arid (Satara) and semi-mesic (Pretoriuskop) site within the Kruger National Park despite significant differences in rainfall totals (t-test: tl, III = 4.40, P < 0.000, F-ratio 3.41). Results from a soil-water model show that seedling recruitment can occur at least twice a decade in the Satara area, which should be frequent enough to allow a transition to a woodland state over time. These results suggest that a mechanism other than the effect of rainfall variability on seedling establishment is required to explain the co-existence of trees and grasses at Satara. The lack of field germination, the absence of a seed bank and the germination of added seed at the field experiment site after rainfall emphasizes seed limitation as an important bottleneck at Satara. Higher herbivore biomass at Satara compared to Pretoriuskop may limit seedling establishment opportunities by destroying seed and seedlings of tree species.en_ZA
dc.identifier.apacitationBotha, S. (2006). <i>The influence of rainfall variability on savanna tree seedling establishment</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/6238en_ZA
dc.identifier.chicagocitationBotha, Susan. <i>"The influence of rainfall variability on savanna tree seedling establishment."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2006. http://hdl.handle.net/11427/6238en_ZA
dc.identifier.citationBotha, S. 2006. The influence of rainfall variability on savanna tree seedling establishment. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Botha, Susan AB - My thesis investigates the rainfall requirements necessary for tree seedling survival of different savanna species in the first year of growth. Results from a field drought experiment showed that dry season survival for seedlings of Acacia nigrescens and Philenaptera vialacea was not related to wet season length. Instead mortality was highest immediately after germination despite irrigation to minimize dry spells. Furthermore there was no relationship between seedling size and the length of the dry spell seedlings of Acacia nigrescens and Philenaptera vialacea grown in basalt clay in the greenhouse, could survive. This was in contrast to seedlings of Scleracarya birrea and Terminalia sericea grown in granite sand, where number of dry days survived increased with number of growth days received. There was no significant differences in rainfall variability (t-test: tL III = 1.56, P = 0.121, F-ratio = 1.13) between a semi-arid (Satara) and semi-mesic (Pretoriuskop) site within the Kruger National Park despite significant differences in rainfall totals (t-test: tl, III = 4.40, P < 0.000, F-ratio 3.41). Results from a soil-water model show that seedling recruitment can occur at least twice a decade in the Satara area, which should be frequent enough to allow a transition to a woodland state over time. These results suggest that a mechanism other than the effect of rainfall variability on seedling establishment is required to explain the co-existence of trees and grasses at Satara. The lack of field germination, the absence of a seed bank and the germination of added seed at the field experiment site after rainfall emphasizes seed limitation as an important bottleneck at Satara. Higher herbivore biomass at Satara compared to Pretoriuskop may limit seedling establishment opportunities by destroying seed and seedlings of tree species. DA - 2006 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2006 T1 - The influence of rainfall variability on savanna tree seedling establishment TI - The influence of rainfall variability on savanna tree seedling establishment UR - http://hdl.handle.net/11427/6238 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/6238
dc.identifier.vancouvercitationBotha S. The influence of rainfall variability on savanna tree seedling establishment. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2006 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/6238en_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.titleThe influence of rainfall variability on savanna tree seedling establishmenten_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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