This study contributes to the understanding of soil diversity (pedodiversity) and its significance for the ecosystem. The introduction leads the reader into the fields of biodiversity and its relation to the abiotic environment and highlights the research needs in geo- and pedodiversity. A brief outline of the BIOTA Southern Africa project explains the research background and infrastructure, and subsequently the overarching aims of this study are introduced. The basic concepts of bio-, geo- and pedodiversity are reviewed in more detail in chapter 5 of this thesis.