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An eco-physiological study in relation to water use for tree growth of Eucalyptus camaldulensis and E. globulus on the dry west coast of South Africa
Thesis (MSc) -- University of Stellenbosch, 1998.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867614118714802176 |
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| access_status_str | Open Access |
| author | Gwaitta Magumba, David Andrew |
| author2 | Ellis, F. |
| author_browse | Ellis, F. Gwaitta Magumba, David Andrew |
| author_facet | Ellis, F. Gwaitta Magumba, David Andrew |
| author_sort | Gwaitta Magumba, David Andrew |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc) -- University of Stellenbosch, 1998. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/55808 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:46:57.306Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/55808 An eco-physiological study in relation to water use for tree growth of Eucalyptus camaldulensis and E. globulus on the dry west coast of South Africa Gwaitta Magumba, David Andrew Ellis, F. Stellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science. Eucalyptus camaldulensis -- South Africa Eucalyptus camaldulensis -- Water requirements -- South Africa Eucalyptus camaldulensis -- South Africa -- Growth Eucalyptus globulus -- South Africa Eucalyptus globulus -- Water requirements -- South Africa Eucalyptus globulus -- South Africa -- Growth Dissertations -- Forestry Thesis (MSc) -- University of Stellenbosch, 1998. Two-year-old Eucalyptus camaldulensis and E. globulus were selected for a study of comparative water use for survival and growth in a low rainfall environment, between the 16th September 1993 and the 9th June 1994. The two species were part of 50 Eucalyptus species, provenances and hybrids planted under The Dry Land Afforestation Research Project at Pamponvlei, about 50 km north of Cape Town, on the west coast of South Africa. The study site experiences a Mediterranean climate, with annual rainfall of about 400 mm, 90% falling between April and September. Additional precipitation is in the form of dew and fog. The soils are a sandy, deep (>1500 mm), Psamment, with a seasonal water table superimposed on a dense clay layer, at about 2m depth. Pre-dawn, diurnal Xylem Pressure Potential (XPP) and Stomatal Conductance (g) were measured with a pressure chamber and a diffusion steady state porometer, respectively. Seasonal volumetric soil water changes were investigated with a neutron probe. Stomatal conductance of the two species showed varying diurnal and seasonal trends, but these could be explained by environmental and physiological conditions. Stomatal conductance was mainly controlled by Photosynthetically Active Radiation (PAR) and Vapour Pressure Deficit (VPD) when there was adequate available water in the soil profile. When the soil water became heavily depleted, the pre-dawn XPP became the primary controlling factor. E. camaldulensis attained high gs values when there was adequate available soil water, irrespective of the minimum pre-dawn XPP and diurnal maximum VPD. The species showed extremely low gs readings when low pre-dawn XPP and high diurnal VPD measurements occurred in concert during the virtual depletion of soil water in the dry period. E. globulus showed high gs values when soil water was sufficient, VPD moderate, and under high pre-dawn XPP, with a partially overcast sky. When a low pre-dawn XPP occurred together with moderate to high VPD, E. globulus reduced its gs, regardless of the soil water status. E. globulus exhibited lower pre-dawn and diurnal XPP measurements than E. camaldulensis, at the end of the dry season and did not recover readily as the latter, when the rain came. Wind reduced the gs variability in mature leaves, but virtually stopped gs in physiologically immature leaves of both species. Dew and fog reduced the gs and water stress in trees during the dry period. Stomatal conductance mean values were divided into three seasons according to stomatal response to environmental conditions. E. camaldulensis consistently showed higher gs mean values (cm s⁻¹) for mean leaf surface (plan ar ea) in all the three seasons, respectively, of 0.292, 0.463 and 0.293 than E. globulus of 0.268, 0.234 and 0.171. The mean leaf area for E. globulus at the end of the study was three times higher than for E. camaldulensis. What was not certain was the proportion of the leaves effectively conducting water vapour, and their relative contribution of gs for each species. The neutron probe investigation confirmed that E. camaldulensis depleted soil water at a higher rate than E. globulus between September and November 1993. The continued high gs rates by E. camaldulensis indicated that the species was drawing water from other sources not detected by the neutron probe. The water table did not refill during the 1993/94 season. When drought occurred in 1994/95, many trees of E. globulus died, but E. camaldulensis did not show signs of damage. The mean biomass index increment (height*(DBH)²) was about 23% more for E. globulus than for E. camaldulensis but the latter grew by 200% and the former by 140%, by the same indices. However, the xeromorphic characters of E. camaldulensis, supported by its better developed root system, showed that the species is more drought-hardy than E. globulus, and therefore, more suitable for afforestation than the latter species on the sandy soils of the dry land of the west coast of South Africa. Masters 2012-08-27T11:37:14Z 2012-08-27T11:37:14Z 1998 Thesis http://hdl.handle.net/10019.1/55808 en Stellenbosch University 180 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Eucalyptus camaldulensis -- South Africa Eucalyptus camaldulensis -- Water requirements -- South Africa Eucalyptus camaldulensis -- South Africa -- Growth Eucalyptus globulus -- South Africa Eucalyptus globulus -- Water requirements -- South Africa Eucalyptus globulus -- South Africa -- Growth Dissertations -- Forestry Gwaitta Magumba, David Andrew An eco-physiological study in relation to water use for tree growth of Eucalyptus camaldulensis and E. globulus on the dry west coast of South Africa |
| title | An eco-physiological study in relation to water use for tree growth of Eucalyptus camaldulensis and E. globulus on the dry west coast of South Africa |
| title_full | An eco-physiological study in relation to water use for tree growth of Eucalyptus camaldulensis and E. globulus on the dry west coast of South Africa |
| title_fullStr | An eco-physiological study in relation to water use for tree growth of Eucalyptus camaldulensis and E. globulus on the dry west coast of South Africa |
| title_full_unstemmed | An eco-physiological study in relation to water use for tree growth of Eucalyptus camaldulensis and E. globulus on the dry west coast of South Africa |
| title_short | An eco-physiological study in relation to water use for tree growth of Eucalyptus camaldulensis and E. globulus on the dry west coast of South Africa |
| title_sort | eco physiological study in relation to water use for tree growth of eucalyptus camaldulensis and e globulus on the dry west coast of south africa |
| topic | Eucalyptus camaldulensis -- South Africa Eucalyptus camaldulensis -- Water requirements -- South Africa Eucalyptus camaldulensis -- South Africa -- Growth Eucalyptus globulus -- South Africa Eucalyptus globulus -- Water requirements -- South Africa Eucalyptus globulus -- South Africa -- Growth Dissertations -- Forestry |
| url | http://hdl.handle.net/10019.1/55808 |
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