Properties of soil pockets on arid Nama Karoo inselbergs - the effect of geology and derived landforms

Soil pockets in desert mountain habitats are extremely important, as they offer a foothold for seedlings, usually have more plant available water and thus provide a favourable habitat for plant growth in an and surrounding. This study investigated properties of soil pockets of isolated arid mountains (i.e. inselbergs), asking the following questions: Does the underlying geology influence soil properties and if so, in what way? What is the effect of topography, i.e. position on slope and landform? Does slope aspect influence soil properties? Soil samples from four and study areas in Namibia along a north-south gradient, each comprising a set of inselbergs, were analysed and tested for differences in geology, habitat (representing a topographic gradient) and slope aspect. This study showed that on and inselbergs: (a) physical soil properties were determined by the underlying geology, (b) chemical soil properties were influenced by the underlying geology and likely biogenic processes as well as atmospheric input, (c) soil properties were affected by topography and landform, but (d) soil properties were not influenced by slope aspect. The role of inselbergs contributing nutrients to surrounding lowlands may be critical to maintain functioning ecosystems and landscapes. Inselbergs could thus serve as sources of nutrients as well as seeds, an important aspect to be considered in conservation and resource planning. (C) 2002 Elsevier Science Ltd.