Impacts of Subdivision of Ranches on Land Cover and Rangeland Resources in Malili Division, Makueni County, Kenya
Kiarie, Crispus Kamau
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Information on impacts of subdivision of ranches on land cover is important as it forms vital baseline among others for the detection of impacts of degradation of rangeland and economic resources in the area. This study was conducted between May and November, 2012. The broad objective for the study was to assess the impacts of subdivision of ranches and subsequent land use change on land cover and rangeland resources in the study area. The research employed various data collection methodologies including descriptive cross-sectional household survey, analysis of geo-spatial data, focused group discussions (FGD), as well as ecological sampling in order to collect qualitative and quantitative data. The study area was subdivided into four clusters, based on the time of subdivision and duration of human settlement. Primary data was collected by use of questionnaires, observations checklists and analyzed using statistical programme for social scientists (SPSS). Data on land cover changes over the 30 year period between 1980 and 2010 was derived from analysis of landsat imagery scenes for the area using various computer software such as ArcGIS, ERDAS IMAGINE 9.1 and ENVI 4.1. Results from this study indicate that the land cover in the study area has under gone significant transformation over the period between 1980 and 2010. Area under woodland declined by 36.01% from 60.79 to 38.90 km2; wooded grassland declined by 35.69% from 142.6 to 123.3 km2; cropland increased by 487.61% from 23.91 to 140.48 km2 while grassland declined by 45.33% from 97.84 km2 to 53.49 km2. Land use patterns in the area have shifted significantly over the 30 year period. Mean duration of settlement was 44.97 years in cluster 1, 26.63 years in cluster 2, and 4.7 years in cluster 3. This study revealed that changes in various land cover types over time is closely related to the human settlement patterns in the area. According to this study, the mean tree density was 76.11±12.8, 43.52±9.1, 24.88±4.4 in clusters 1, 2, and 3 compared to 109.60±12.9 in the control. Grazing pressure was significantly high in the settled areas, while the range condition was poorer in the settled areas when compared with the existing ranch. The study further revealed that a majority of respondents have experienced a decline in the supply of various rangeland resources. Access to various environmental resources such as water, firewood, charcoal, construction materials, and pasture has been declining according to 66.5, 88.0, 91.0, 84.6 and 76.8 percent of respondents respectively. The study identified charcoal burning and cultivation as the major causes of decline in natural vegetation cover according to 54.2 and 47.7 percent of respondents respectively. The study findings indicate that, crop yields, livestock productivity and household incomes have been declining over the last five years according to 79.2, 66.9 and 67.1 percent of respondents respectively. The study recommends that policies and strategies be instituted to discourage further fragmentation of rangelands in the study area. The study recommends further research to determine the impacts of habitat fragmentation primary and secondary productivity in the area, as well as developing thresholds and standards necessary for ensuring sustainable utilization and checking further degradation in the rangelands.