The consequences of precipitation seasonality for Mediterranean-ecosystem vegetation of South Africa

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dc.contributor.authorCramer, Michael Den_ZA
dc.contributor.authorHoffman, M Timmen_ZA
dc.date.accessioned2015-12-20T16:08:29Z
dc.date.available2015-12-20T16:08:29Z
dc.date.issued2015en_ZA
dc.description.abstractGlobally, mediterranean-climate ecosystem vegetation has converged on an evergreen, sclerophyllous and shrubby growth form. The particular aspects of mediterranean-climate regions that contribute to this convergence include summer droughts and relatively nutrient-poor soils. We hypothesised that winter-precipitation implies stressful summer droughts and leaches soils due to greater water availability (i.e. balance between precipitation and potential evapotranspiration; P-PET) during cold periods. We conducted a comparative analysis of normalised difference vegetation indices (NDVI) and edaphic and climate properties across the biomes of South Africa. NDVI was strongly correlated with both precipitation and P-PET (r 2 = 0.8). There was no evidence, however, that winter-precipitation reduces NDVI in comparison to similar amounts of summer-precipitation. Base saturation (BS), a measure of soil leaching was, however, negatively related to P-PET (r 2 = 0.64). This led to an interaction between P-PET and BS in determining NDVI, indicating the existence of a trade-off between water availability and soil nutrients that enables NDVI to increase with precipitation, despite negative consequences for soil nutrient availability. The mechanism of this trade-off is suggested to be that water increases nutrient accessibility. This implies that along with nutrient-depauperate geologies and long periods of time since glaciation, the winter-precipitation may have contributed to the highly leached status of the soils. Since many of the ecophysiological characteristics of mediterranean-ecosystem flora are associated with low nutrient availabilities (e.g. evergreen foliage, sclerophylly, cluster roots), we conclude that mediterranean-climates promote convergence of growth-forms in these regions through high leaching capacity.en_ZA
dc.identifier.apacitationCramer, M. D., & Hoffman, M. T. (2015). The consequences of precipitation seasonality for Mediterranean-ecosystem vegetation of South Africa. <i>PLoS One</i>, http://hdl.handle.net/11427/15932en_ZA
dc.identifier.chicagocitationCramer, Michael D, and M Timm Hoffman "The consequences of precipitation seasonality for Mediterranean-ecosystem vegetation of South Africa." <i>PLoS One</i> (2015) http://hdl.handle.net/11427/15932en_ZA
dc.identifier.citationCramer, M. D., & Hoffman, M. T. (2015). The consequences of precipitation seasonality for Mediterranean-ecosystem vegetation of South Africa. PloS one, 10(12). doi:10.1371/journal.pone.0144512en_ZA
dc.identifier.ris TY - Journal Article AU - Cramer, Michael D AU - Hoffman, M Timm AB - Globally, mediterranean-climate ecosystem vegetation has converged on an evergreen, sclerophyllous and shrubby growth form. The particular aspects of mediterranean-climate regions that contribute to this convergence include summer droughts and relatively nutrient-poor soils. We hypothesised that winter-precipitation implies stressful summer droughts and leaches soils due to greater water availability (i.e. balance between precipitation and potential evapotranspiration; P-PET) during cold periods. We conducted a comparative analysis of normalised difference vegetation indices (NDVI) and edaphic and climate properties across the biomes of South Africa. NDVI was strongly correlated with both precipitation and P-PET (r 2 = 0.8). There was no evidence, however, that winter-precipitation reduces NDVI in comparison to similar amounts of summer-precipitation. Base saturation (BS), a measure of soil leaching was, however, negatively related to P-PET (r 2 = 0.64). This led to an interaction between P-PET and BS in determining NDVI, indicating the existence of a trade-off between water availability and soil nutrients that enables NDVI to increase with precipitation, despite negative consequences for soil nutrient availability. The mechanism of this trade-off is suggested to be that water increases nutrient accessibility. This implies that along with nutrient-depauperate geologies and long periods of time since glaciation, the winter-precipitation may have contributed to the highly leached status of the soils. Since many of the ecophysiological characteristics of mediterranean-ecosystem flora are associated with low nutrient availabilities (e.g. evergreen foliage, sclerophylly, cluster roots), we conclude that mediterranean-climates promote convergence of growth-forms in these regions through high leaching capacity. DA - 2015 DB - OpenUCT DO - 10.1371/journal.pone.0144512 DP - University of Cape Town J1 - PLoS One LK - https://open.uct.ac.za PB - University of Cape Town PY - 2015 T1 - The consequences of precipitation seasonality for Mediterranean-ecosystem vegetation of South Africa TI - The consequences of precipitation seasonality for Mediterranean-ecosystem vegetation of South Africa UR - http://hdl.handle.net/11427/15932 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/15932
dc.identifier.urihttp://dx.doi.org/10.1371/journal.pone.0144512
dc.identifier.vancouvercitationCramer MD, Hoffman MT. The consequences of precipitation seasonality for Mediterranean-ecosystem vegetation of South Africa. PLoS One. 2015; http://hdl.handle.net/11427/15932.en_ZA
dc.language.isoengen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_ZA
dc.rights.holder© 2015 Cramer, Hoffmanen_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/4.0en_ZA
dc.sourcePLoS Oneen_ZA
dc.source.urihttp://journals.plos.org/plosoneen_ZA
dc.subject.otherEcosystemsen_ZA
dc.subject.otherGrasslandsen_ZA
dc.subject.otherRainen_ZA
dc.subject.otherSouth Africaen_ZA
dc.subject.otherSummeren_ZA
dc.subject.otherWinteren_ZA
dc.subject.otherCation exchange capacityen_ZA
dc.subject.otherWater resourcesen_ZA
dc.titleThe consequences of precipitation seasonality for Mediterranean-ecosystem vegetation of South Africaen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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