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Universität Hamburg (2008)

Pedodiversity of southern African drylands

Petersen, Andreas

Titre : Pedodiversity of southern African drylands

Auteur : Petersen, Andreas

Université de soutenance : Universität Hamburg

Grade : Doktorgrades der Naturwissenschaften 2008

Présentation
Soil represents the critical interface between atmosphere, lithosphere, biosphere and hydrosphere and is thus an ideal integrative component reflecting the variety of influences. Moreover, it is the most important resource for biotic components and thus strongly affects biodiversity. On local to regional scales, abiotic environmental heterogeneity is assumed as the most important driver for species richness and patterns besides biotic population interaction. Pedodiversity is a way of measuring soil variation and can be used as an integrative index for soil information and comparative diversity analyses. Pedodiversity can be regarded with respect to different aspects such as taxonomic, genetic, parametric and functional diversity. Understanding and maintaining ecosystem functions are the primary purposes of pedodiversity studies using relatively new techniques for the assessment of soil variability. This thesis aims to analyse the pedodiversity of defined dryland areas in southern Africa. The study contributes to the understanding of soil diversity (pedodiversity) and its significance for the ecosystem. The first major aim of this study was to close the gap of knowledge regarding the distribution and pattern of soils on both, a habitat orientated local scale (< 10 m – 1000 m <) and a sub-continental scale by analysing 22 survey sites (biodiversity observatories) of 1 km2 in size along a transect of 2,500 km from Northern Namibia to the Cape region. In order to apply a comprehensive approach for the quantification of the abiotic diversity, the second major aim of this study focuses on the methods to quantify pedodiversity. The further development of criteria for pedodiversity and the relation of parameter-orientated pedodiversity indices to biodiversity will provide a future tool to quantify the relationship between pedo- and e.g. phytodiversity and will help to discriminate between the influence of soil and other factors. The study is embedded in the BIOTA Southern Africa project, an interdisciplinary research approach with focus on monitoring ecosystem functions such as biodiversity under different land-use aspects (www.biota-africa.org). The study area is located in southern Africa stretching from Northern Namibia to the Cape region covering all major biomes and various ‘biodiversity hotspots’ represented by study sites of 1 km2 in size (biodiversity observatories). The northern part of the study region is characterised by subtropical summer rainfall while the southern part is dominated by winter rainfall, each with a range from 50 to 500 mm mean annual precipitation. Each observatory is subdivided into 100 ha plots and sampled by a stratified random selection of 25 profiles. Background and context of this central transdisciplinary sampling scheme are introduced and discussed.

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