The relationships between vegetation, soils and ecosystem dynamics for land degradation control in Ngurunit, Marsabit district, 2006

Abstract

Naturally growing or planted trees alone is not enough to control land degradation. Rehabilitation and sustainable use of the degraded ecosystems require integrated analysis of soil quality and vegetation as important components of ecosystem structure and functions. Such analysis forms basis of formulating the appropriate intervention strategies. This approach was applied in Ngurunit, and the results show that diversity in soil characteristics relates to diversity in plant species along the transect from the foot of Ndutu mountains to Lepidera. On the Acrisols, the main plant species are Acacia Senegal and comiphora, while Acacia tortilis occurs mainly on Lixisols, Arenosls and Solonetz. Acacia seyal, mellifera and ruficiens are found on the Vertisols. The degree of land degradation and the consequences of desertification processes also vary with different soil types. Land degradation is most severe on the red soils with compact B horizon occurring between steep mountain slopes and the low-lying plains. Use of micro-catchments between these slopes and the plains may not only check the run-off speed, but also increase the water uptake and storage capacity of the soil by breaking the compact layer. The run-off water, reaching the highly permeable plains, may provide the opportunity for increased water supply. This is because the water percolating through the soil may be tapped using shallow wells, which are cheap to construct, and can increase water supply, not only for domestic consumption, but also irrigation of the kitchen gardens for improved livelihoods.