Soil water movement and nutrient cycling in semi-arid rangeland: vegetation change and system resilience

Abstract

Abstract:Recent decades have seen rapid intensi®cation of cattle production in semi-arid savannah ecosystems, increasingly on formalized ranch blocks. As a result, vegetation community changes have occurred, notably bush encroachment (increased bush dominance) in intensively grazed areas.

Participatory Indicator Development: What Can Ecologists and Local Communities Learn From Each Other

“…This included soil crusts, which have been used as indicators of rangeland condition in manuals targeted at pastoralists elsewhere in Southern Africa (Milton et al 1998). Some indicators from the literature were considered irrelevant to the study area, such as soil compaction, which is not a problem in Kalahari soils due to their consistently high proportion of fine sands (Dougill et al 1998). In some instances, pastoralists took direct issue with indicators from the literature.…”

Biogeochemistry of Kalahari sands

“…This is a major limitation as the response of arid and semiarid ecosystems to changes in rainfall regime is mediated by variations in the soil moisture dynamics, which, in turn, depend on the soil hydraulic properties. In contrast, a few studies have investigated the biogeochemical properties of the Kalahari sands Bird et al, 2004;Dougill et al, 1998;Feral et al, 2003;Hudak et al, 2003;Pardo et al, 2003;Skarpe and Bergstrom, 1986), although a comprehensive synthesis of the main results remains to be accomplished. This paper provides a brief review of previous studies on the sandy Kalahari soils (hereafter called the Kalahari sands) combined with previously unpublished results from recent analyses of the soil physical (mostly hydraulic) and biogeochemical properties.…”

Spatial and temporal distribution of cyanobacterial soil crusts in the Kalahari: Implications for soil surface properties

“…Kalahari Sand soils typically consist of over 95% fine sand-sized sediments and are predominantly deep, structureless and nutrient deficient (Dougill et al, 1998). The Kalahari includes areas of both active sediment movement and stable surfaces, with much research focusing on the importance of surface vegetation cover (Wiggs et al, 1994(Wiggs et al, , 1995 and climate change (Thomas et al, 1997;Knight et al, 2004;Thomas et al, 2005) in affecting sediment mobility, notably in the arid south west of Botswana.…”