An investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserve
| dc.contributor.advisor | Bond, William J | en_ZA |
| dc.contributor.author | Taylor, Robert | en_ZA |
| dc.date.accessioned | 2017-11-01T08:47:23Z | |
| dc.date.available | 2017-11-01T08:47:23Z | |
| dc.date.issued | 2003 | en_ZA |
| dc.date.updated | 2017-02-14T10:25:17Z | |
| dc.description.abstract | We hypothesized that rainwater had a different and distinct isotopic signal to groundwater, and thus plants growing on groundwater-fed areas would have a unique and distinct isotopic composition compared to plants growing on freely-drained soils. We studied two groundwater-fed areas and adjacent freely-drained areas in the Cape Point Nature Reserve, Cape Peninsula. We sampled groundwater and analyzed the isotopic composition and compared this to the isotope composition of rainfall. We found that δ¹⁸O and oD values of rainwater (δ¹⁸O = O%o to -5.6%o and oD = +11 %o to -22%o) overlapped the isotopic composition of groundwater (δ¹⁸O = -4.2%o to -4.5%o and oD = -11.9%o to -13.2%o). Thus isotopic analysis could not determine which areas were groundwater-fed and which were rain-fed. We also sampled xylem water from five species, namely Leucadendron laureolum and Metalasia muricata (both of which grew on both dry and wetland areas), Mimetes hirtus (wetland only), Erica labialis (dry area only), and Erica multumbellifera (wet area orily). Our results suggest that both of L. laureolum and Metalasia muricata had access to groundwater on both groundwater-fed sites and the free-drained site. E. multumbellifera at a groundwater-fed marsh was likely also using groundwater, however on the adjacent freely drained site E. labialis was likely using rainwater. M. hirtus had a much more positive isotopic composition (δ¹⁸O = -1.5 ±1.2%o and δD = 5.1 ± 18.0%o) than either groundwater or rainwater, indicating that it was using evaporated water, which suggests the species were very shallow rooted. Thus M. hirtus would be very sensitive to drying out of the soil. This study has demonstrated that stable water isotopes cannot clearly distinguish rainwater and groundwater and we may have use other methods such as thermal imagery, chemical analysis, and xylem pressure potentials to determine the degree of dependency of vegetation on groundwater. | en_ZA |
| dc.identifier.apacitation | Taylor, R. (2003). <i>An investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserve</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/25993 | en_ZA |
| dc.identifier.chicagocitation | Taylor, Robert. <i>"An investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserve."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2003. http://hdl.handle.net/11427/25993 | en_ZA |
| dc.identifier.citation | Taylor, R. 2003. An investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserve. University of Cape Town. | en_ZA |
| dc.identifier.ris | TY - Thesis / Dissertation AU - Taylor, Robert AB - We hypothesized that rainwater had a different and distinct isotopic signal to groundwater, and thus plants growing on groundwater-fed areas would have a unique and distinct isotopic composition compared to plants growing on freely-drained soils. We studied two groundwater-fed areas and adjacent freely-drained areas in the Cape Point Nature Reserve, Cape Peninsula. We sampled groundwater and analyzed the isotopic composition and compared this to the isotope composition of rainfall. We found that δ¹⁸O and oD values of rainwater (δ¹⁸O = O%o to -5.6%o and oD = +11 %o to -22%o) overlapped the isotopic composition of groundwater (δ¹⁸O = -4.2%o to -4.5%o and oD = -11.9%o to -13.2%o). Thus isotopic analysis could not determine which areas were groundwater-fed and which were rain-fed. We also sampled xylem water from five species, namely Leucadendron laureolum and Metalasia muricata (both of which grew on both dry and wetland areas), Mimetes hirtus (wetland only), Erica labialis (dry area only), and Erica multumbellifera (wet area orily). Our results suggest that both of L. laureolum and Metalasia muricata had access to groundwater on both groundwater-fed sites and the free-drained site. E. multumbellifera at a groundwater-fed marsh was likely also using groundwater, however on the adjacent freely drained site E. labialis was likely using rainwater. M. hirtus had a much more positive isotopic composition (δ¹⁸O = -1.5 ±1.2%o and δD = 5.1 ± 18.0%o) than either groundwater or rainwater, indicating that it was using evaporated water, which suggests the species were very shallow rooted. Thus M. hirtus would be very sensitive to drying out of the soil. This study has demonstrated that stable water isotopes cannot clearly distinguish rainwater and groundwater and we may have use other methods such as thermal imagery, chemical analysis, and xylem pressure potentials to determine the degree of dependency of vegetation on groundwater. DA - 2003 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2003 T1 - An investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserve TI - An investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserve UR - http://hdl.handle.net/11427/25993 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/25993 | |
| dc.identifier.vancouvercitation | Taylor R. An investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserve. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2003 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/25993 | en_ZA |
| dc.language.iso | eng | en_ZA |
| dc.publisher.department | Department of Biological Sciences | en_ZA |
| dc.publisher.faculty | Faculty of Science | en_ZA |
| dc.publisher.institution | University of Cape Town | |
| dc.subject.other | Botany | en_ZA |
| dc.subject.other | Biological Conservation | en_ZA |
| dc.subject.other | Plant Ecology | en_ZA |
| dc.title | An investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserve | en_ZA |
| dc.type | Bachelor Thesis | |
| dc.type.qualificationlevel | Honours | |
| dc.type.qualificationname | BSc (Hons) | en_ZA |
| uct.type.filetype | ||
| uct.type.filetype | Text | |
| uct.type.filetype | Image | |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Thesis | en_ZA |