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Does tree size matter? : giraffe influence on African savanna ecosystem properties
Trees alter the environment by affecting microclimate, soil properties and adding structural complexity to an otherwise single stratum system. It is known that the herbaceous understory of Savanna ecosystems is most productive at intermediate tree density, where the shade and nutrients from the tree...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2017
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| _version_ | 1867613278250729472 |
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| access_status_str | Open Access |
| author | Soutschka, Nadine |
| author2 | Bond, William J |
| author_browse | Bond, William J Soutschka, Nadine |
| author_facet | Bond, William J Soutschka, Nadine |
| author_sort | Soutschka, Nadine |
| collection | Thesis |
| description | Trees alter the environment by affecting microclimate, soil properties and adding structural complexity to an otherwise single stratum system. It is known that the herbaceous understory of Savanna ecosystems is most productive at intermediate tree density, where the shade and nutrients from the tree are more influential than the competition with the tree. Tree density varies in savannas due to disturbances, such as fire and herbivory. Yet, disturbances do not only alter density but can affect entire tree structure. It has been found that chronic ungulate browsing influences whole tree size, as well as canopy size and shape. Giraffe in south of Kruger National Park browse heavily on Acacia nigrescens found on basalt-derived soils. I studied the influence of trees above the giraffe browse trap (>6 m) as opposed to trees in the browse trap (< 6 m) on savanna ecosystem properties. I compared grass biomass, soil moisture, soil organic matter, soil carbon and soil nitrogen beneath tall trees vs. short trees, as well as in the open vs. underneath trees. Ecosystem properties were estimated and compared between a giraffe impacted to a giraffe absent area. Giraffe impacted area overall yielded lower grass biomass, soil moisture, soil nitrogen and soil carbon. The consequence is a trophic cascade of events from increased giraffe decreasing fires and in tum increasing tree density and hence carbon sequestration. As giraffes replace a single large tree by several small trees, shows that their population size is key determinant of ecosystem properties. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/25765 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:35.758Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/25765 Does tree size matter? : giraffe influence on African savanna ecosystem properties Soutschka, Nadine Bond, William J Botany Biological Conservation Trees alter the environment by affecting microclimate, soil properties and adding structural complexity to an otherwise single stratum system. It is known that the herbaceous understory of Savanna ecosystems is most productive at intermediate tree density, where the shade and nutrients from the tree are more influential than the competition with the tree. Tree density varies in savannas due to disturbances, such as fire and herbivory. Yet, disturbances do not only alter density but can affect entire tree structure. It has been found that chronic ungulate browsing influences whole tree size, as well as canopy size and shape. Giraffe in south of Kruger National Park browse heavily on Acacia nigrescens found on basalt-derived soils. I studied the influence of trees above the giraffe browse trap (>6 m) as opposed to trees in the browse trap (< 6 m) on savanna ecosystem properties. I compared grass biomass, soil moisture, soil organic matter, soil carbon and soil nitrogen beneath tall trees vs. short trees, as well as in the open vs. underneath trees. Ecosystem properties were estimated and compared between a giraffe impacted to a giraffe absent area. Giraffe impacted area overall yielded lower grass biomass, soil moisture, soil nitrogen and soil carbon. The consequence is a trophic cascade of events from increased giraffe decreasing fires and in tum increasing tree density and hence carbon sequestration. As giraffes replace a single large tree by several small trees, shows that their population size is key determinant of ecosystem properties. 2017-10-25T07:58:00Z 2017-10-25T07:58:00Z 2010 2017-02-16T11:37:13Z Bachelor Thesis Honours BSc (Hons) http://hdl.handle.net/11427/25765 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Botany Biological Conservation Soutschka, Nadine Does tree size matter? : giraffe influence on African savanna ecosystem properties |
| thesis_degree_str | Bachelor's / Honours |
| title | Does tree size matter? : giraffe influence on African savanna ecosystem properties |
| title_full | Does tree size matter? : giraffe influence on African savanna ecosystem properties |
| title_fullStr | Does tree size matter? : giraffe influence on African savanna ecosystem properties |
| title_full_unstemmed | Does tree size matter? : giraffe influence on African savanna ecosystem properties |
| title_short | Does tree size matter? : giraffe influence on African savanna ecosystem properties |
| title_sort | does tree size matter giraffe influence on african savanna ecosystem properties |
| topic | Botany Biological Conservation |
| url | http://hdl.handle.net/11427/25765 |
| work_keys_str_mv | AT soutschkanadine doestreesizemattergiraffeinfluenceonafricansavannaecosystemproperties |