LAND USE LAND COVER CHANGES AND THEIR IMPLICATIONS ON LAND DEGRADATION IN ELGEYO ESCARPMENT, KENYA

Abstract

Land use land cover (LULC) changes have become common experience globally with detrimental impacts on the environment. In Elgeyo Marakwet County, agriculture and settlements have extended to the Elgeyo escarpment. However, information on their extent and implications on soil properties and erosion in the escarpment is scanty. This was despite of its fragility, importance as rivers source and tourism. The study mainly determined the implications of LULC changes on land degradation in Elgeyo escarpment. Specifically it; determined LULC dynamics and their drivers, assessed the impact of LULC conversions on soil erosion occurrence and soil properties in Elgeyo escarpment. Landsat 5 (1995) and Landsat 8 satellite images for 2014 and 2020 were downloaded from United States Geological survey website. A structured questionnaire was administered to 180 respondents sampled via snowball method, eight focus group discussions and seven key informant interviews were performed. Sixty soil samples from four purposively selected sites were analyzed using standard laboratory procedures. Remote sensing and geographic information system were used to examine LULC dynamics while Revised Universal Soil Loss Equation was used to compute soil erosion. Differences in soil parameters among LULC classes were tested using one-way ANOVA. The results indicate that in 1995-2014 period, forest, built-up and cropland gained by 411.8%, 201% and 13.6%, respectively while grassland and shrubland decreased by 78.2% and 24.4% respectively. In 2014-2020, grassland, built-up, shrubland and cropland decreased by 79.7%, 39.1%, 21.7% and 11.8% respectively while forest cover increased by 63%. LULC changes were driven by population growth (97.8%), food demand (88.9%) and conflict (44.4%). Average soil erosion in 1995 and 2020 were 14.02 tha-1y-1 and 18.76 tha-1y-1 respectively. Soil erosion occurrence was 67.1% in Shrubland in 1995 but declined to 39.8% by 2020, comparable to that in forest (39.4%). Soil erosion increased with slope and sections with slope >300 encountering the highest (1225 t/ha/y) owing to high rainfall erosivity. Soil properties differed among LULC classes. Soil pH was slightly acid (6.20) in forest and moderately acid (5.38) in cropland. Organic carbon was high (4.83 %) in forest and moderate (2.57%) in cropland. Nitrogen levels were moderate (0.12-0.23%) across all LULC classes. Phosphorous was high in forest (81.85 ppm) whereas potassium was high in forest (872.67 ppm). Moisture contents were 19.70% and 14.34% respectively in forest and cropland. Forest had the most (1.00 g/cm3) and cropland the least (1.40 g/cm3) favorable soil bulk density. There were profound LULC changes. The conversion of natural ecosystems to farmlands accelerated soil erosion and decline in soil physicochemical properties. Accordingly, enhanced implementation of farm forestry rules, land management laws, Land adjudication and adoption of beekeeping are crucial to sustainably conserve this escarpment.