The contribution of fog to the moisture and nutritional supply of Arthraerua leubnitziae in the central Namib Desert, Namibia

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dc.contributor.advisorEckardt, Franken_ZA
dc.contributor.advisorCramer, Michael Den_ZA
dc.contributor.authorGottlieb, Tunehafo Ruusaen_ZA
dc.date.accessioned2018-05-07T09:16:55Z
dc.date.available2018-05-07T09:16:55Z
dc.date.issued2018en_ZA
dc.description.abstractFog is a key source of moisture to the diverse coastal Namib Desert biota, delivering five times more moisture than rain. Apart from the importance of fog as a source of water for plants, it is also associated with particulates that may contain essential nutrients for plants. Furthermore, dry deposition can be an important input of nutrients to many ecosystems, but without water, dust deposited on leaves or on soil is inaccessible for plant uptake. In other studies of coastal ecosystems (e.g. Strandveld), it has been found that this combined deposition of nutrients represents a major source of nutrients to terrestrial ecosystems. In the case of the Namib Desert, the range of Arthraerua leubnitziae is limited to those areas where fog occurs. This study was carried out at five meteorological stations in the gravel plains of the Namib Desert, along an east-west transect increasing in elevation inland. I hypothesised that marine-derived deposition contributes to moisture and nutrient supply of Arthraerua leubnitziae, an endemic shrub restricted to the fog zone of the central Namib Desert, and consequently determines its distribution. To test this hypothesis, two sub-hypotheses were developed and tested independently. The first sub-hypothesis was that fog contributed to the distribution range of A. leubnitziae in the central Namib Desert and the second was that fog deposition has a significant potential to supply moisture and nutrients to A. leubnitziae in the central Namib Desert. To test the first sub-hypothesis, I measured fog and rain volume, and plant morphological characteristics at the five sites. In addition, a fog map was derived using climatic variables from the five sites and used with climate and edaphic variables in MaxEnt model of the probability of occurrence of A. leubnitziae. The occurrence of A. leubnitziae was found to coincide with areas with high fog occurrence with fog contributing 36% to the modelled distribution of A. leubnitziae alongside precipitation, elevation and isothermality. In order to test the second sub-hypothesis, I measured nutrients deposited in fog water derived from wet and dry deposition (Ca, K, Mg, Na, Cl, Br, NO₃, PO₄ and SO₄) and plant essential nutrients in plant and soil samples (N, P, K, Ca, Mg, Mn, Fe, Cu and Zn). I also determined the nutrient uptake by stems of A. leubnitziae. During the period of Sep 2015 to Aug 2016, fog provided 92% of the yearly water input across the study sites. Over the course of the sampling cycle, the total annual nutrient content of fog and dust was dominated by Ca and Na. Most of the nutrients (K, Mg, Na, and S) were of marine origin. However, Ca enrichment factors (relative to seawater) were higher than 1, suggesting an input from dust. A. leubnitziae was found to be able to directly intercept and absorb some of the nutrients in the dust and fog via their stems. Even though plant and soil nutrients did not match each other, a contribution to plant nutrition from dust and fog was evident. The low nutrient concentrations in the soils of the Namib Desert and significant inputs from dust and fog suggests deposition is an important source of nutrients for A. leubnitziae. Although work is still required to better understand the importance of fog water uptake for nutrient provision, I have identified that water, nutrients and environmental stress alleviation should not be considered separately in studying the role of fog as a determinant of plant distributions.en_ZA
dc.identifier.apacitationGottlieb, T. R. (2018). <i>The contribution of fog to the moisture and nutritional supply of Arthraerua leubnitziae in the central Namib Desert, Namibia</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science. Retrieved from http://hdl.handle.net/11427/27949en_ZA
dc.identifier.chicagocitationGottlieb, Tunehafo Ruusa. <i>"The contribution of fog to the moisture and nutritional supply of Arthraerua leubnitziae in the central Namib Desert, Namibia."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 2018. http://hdl.handle.net/11427/27949en_ZA
dc.identifier.citationGottlieb, T. 2018. The contribution of fog to the moisture and nutritional supply of Arthraerua leubnitziae in the central Namib Desert, Namibia. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Gottlieb, Tunehafo Ruusa AB - Fog is a key source of moisture to the diverse coastal Namib Desert biota, delivering five times more moisture than rain. Apart from the importance of fog as a source of water for plants, it is also associated with particulates that may contain essential nutrients for plants. Furthermore, dry deposition can be an important input of nutrients to many ecosystems, but without water, dust deposited on leaves or on soil is inaccessible for plant uptake. In other studies of coastal ecosystems (e.g. Strandveld), it has been found that this combined deposition of nutrients represents a major source of nutrients to terrestrial ecosystems. In the case of the Namib Desert, the range of Arthraerua leubnitziae is limited to those areas where fog occurs. This study was carried out at five meteorological stations in the gravel plains of the Namib Desert, along an east-west transect increasing in elevation inland. I hypothesised that marine-derived deposition contributes to moisture and nutrient supply of Arthraerua leubnitziae, an endemic shrub restricted to the fog zone of the central Namib Desert, and consequently determines its distribution. To test this hypothesis, two sub-hypotheses were developed and tested independently. The first sub-hypothesis was that fog contributed to the distribution range of A. leubnitziae in the central Namib Desert and the second was that fog deposition has a significant potential to supply moisture and nutrients to A. leubnitziae in the central Namib Desert. To test the first sub-hypothesis, I measured fog and rain volume, and plant morphological characteristics at the five sites. In addition, a fog map was derived using climatic variables from the five sites and used with climate and edaphic variables in MaxEnt model of the probability of occurrence of A. leubnitziae. The occurrence of A. leubnitziae was found to coincide with areas with high fog occurrence with fog contributing 36% to the modelled distribution of A. leubnitziae alongside precipitation, elevation and isothermality. In order to test the second sub-hypothesis, I measured nutrients deposited in fog water derived from wet and dry deposition (Ca, K, Mg, Na, Cl, Br, NO₃, PO₄ and SO₄) and plant essential nutrients in plant and soil samples (N, P, K, Ca, Mg, Mn, Fe, Cu and Zn). I also determined the nutrient uptake by stems of A. leubnitziae. During the period of Sep 2015 to Aug 2016, fog provided 92% of the yearly water input across the study sites. Over the course of the sampling cycle, the total annual nutrient content of fog and dust was dominated by Ca and Na. Most of the nutrients (K, Mg, Na, and S) were of marine origin. However, Ca enrichment factors (relative to seawater) were higher than 1, suggesting an input from dust. A. leubnitziae was found to be able to directly intercept and absorb some of the nutrients in the dust and fog via their stems. Even though plant and soil nutrients did not match each other, a contribution to plant nutrition from dust and fog was evident. The low nutrient concentrations in the soils of the Namib Desert and significant inputs from dust and fog suggests deposition is an important source of nutrients for A. leubnitziae. Although work is still required to better understand the importance of fog water uptake for nutrient provision, I have identified that water, nutrients and environmental stress alleviation should not be considered separately in studying the role of fog as a determinant of plant distributions. DA - 2018 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2018 T1 - The contribution of fog to the moisture and nutritional supply of Arthraerua leubnitziae in the central Namib Desert, Namibia TI - The contribution of fog to the moisture and nutritional supply of Arthraerua leubnitziae in the central Namib Desert, Namibia UR - http://hdl.handle.net/11427/27949 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/27949
dc.identifier.vancouvercitationGottlieb TR. The contribution of fog to the moisture and nutritional supply of Arthraerua leubnitziae in the central Namib Desert, Namibia. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 2018 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/27949en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Environmental and Geographical Scienceen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherEnvironmental and Geographical Scienceen_ZA
dc.titleThe contribution of fog to the moisture and nutritional supply of Arthraerua leubnitziae in the central Namib Desert, Namibiaen_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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