Impact of Land-use Change on Ecology, Resource Productivity and Adaptive Strategies of Smallholder Agro-Pastoralists in Machakos-Makueni Districts, Kenya
Kirwa, E C A
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Semi arid areas in Kenya are experiencing socio-economic processes leading to land subdivisions and subsequent changes in land-use patterns. Changes in land-use negatively affect the ecological resource base through replacement of native plant species, loss of wildlife habitats and reduced quality and quantity of water. A study was therefore carried out to analyze the impact of land subdivision and shifts from commercial ranches to smallholder agro-pastoral production systems on the ecological resource base, resource productivity and agro-pastoral adaptive strategies in Machakos and Makueni Districts. Ecological studies involved sampling for vegetation and soil attributes in 2 nonsubdivided cooperative ranches and 3 subdivided ranches with transects cutting across smallholder farms (SMFs). Vegetation and soil samples were analysed for vegetation attributes and physical and chemical properties, respectively, using standard methods. Household survey involving 90 households was also carried out to determine impact of the land-use change and land subdivision on resource productivity and characterize the agro-pastoral adaptive strategies given the shifts. Data for household output and income was analysed using log-log regression models. The SMFs had significantly higher (p:S0.05) frequency and biomass production for annuals grass species while the ranches had higher (p:S0.05) percent ground cover and biomass production for perennial grasses, forbs and litter. This indicated that SMFs were more degraded than the ranches probably due to the attendant continuous cultivation and overgrazing. Significant decline (p:S0.05) in important soil chemical properties was recorded in the SMFs, particularly nitrogen, phosphorus, magnesium, manganese and sodium levels. Soil Organic carbon (SaC) significantly reduced (p:S0.05) with increasing period of subdivision and settlement. There was a significant (p:S0.05) and positive relationship between land size and household output, suggesting that continued fragmentation of land in the rangelands could cause significant decline in household output. In addition, the results show that households in the study were operating below the optimal level of production and would more than double their output if they doubled their inputs including land. Trends in household returns indicated increased returns with increase in land size. In spite of land subdivision" early planting, use of drought resistant crops, predation control and feed conservation were some of the important agro-pastoral adaptive strategies in the study area. But, unreliable rainfall, access to land and water, acquisition of skills, shortage of pasture and predation were the main factors influencing shifts in the adaptive strategies. Fragmentation of ranches and change in land-use to smallholder agro-pastoral production systems in the area should be done in tandem with adoption of technologies that will allow exploitation of land-based resources without compromising on the ecological integrity in the long run. Therefore, there is need to determine land use and size thresholds that will not affect land productivity to meet minimum household requirements of the agro-pastoral system. Furthermore, due to the trends in land degradation in the SMFs, there is urgent need for development of appropriate technologies that would contribute to reversing the degradation trends and increase land productivity in the area.