An investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserve

dc.contributor.advisorBond, William Jen_ZA
dc.contributor.authorTaylor, Roberten_ZA
dc.date.accessioned2017-11-01T08:47:23Z
dc.date.available2017-11-01T08:47:23Z
dc.date.issued2003en_ZA
dc.date.updated2017-02-14T10:25:17Z
dc.description.abstractWe 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.apacitationTaylor, 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/11427/25993en_ZA
dc.identifier.chicagocitationTaylor, 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/11427/25993en_ZA
dc.identifier.citationTaylor, 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.urihttp://hdl.handle.net/11427/25993
dc.identifier.vancouvercitationTaylor 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/11427/25993en_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.subject.otherBiological Conservationen_ZA
dc.subject.otherPlant Ecologyen_ZA
dc.titleAn investigation into using stable water isotopes to determine the dependency of vegetation on groundwater at Cape Point Nature Reserveen_ZA
dc.typeBachelor Thesis
dc.type.qualificationlevelHonours
dc.type.qualificationnameBSc (Hons)en_ZA
uct.type.filetype
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
Taylor_An_investigation_into_using__1.pdf
Size:
860.9 KB
Format:
Adobe Portable Document Format
Description:
License bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
license.txt
Size:
1.72 KB
Format:
Item-specific license agreed upon to submission
Description:
Collections