EFFECTS OF LAND USE/LAND COVER DYNAMICS ON SOIL CARBON STOCK IN THE WESHEM WATERSHED, NORTHERN HIGHLANDS OF ETHIOPIA

Abstract

Land use and land cover changes have created serious effect in Weshem Watershed particularly in soil quality and sustainability. Land use changes can accelerate SOC stock loss through erosion or vegetation conversion, and SOC stocks in surface soil and subsoil can change after the native forest is converted to agricultural systems. Particularly, it is important to investigate the land use and land cover change influence on soil carbon stock (SOC). Thus the study was aimed to investigate effects of land use and land cover dynamics on soil organic carbon stock (SOC) within the Weshem Watershed from 2001-2017. The specific objectives of this study were to analyze the land use land cover dynamics across the reference years, to determine soil organic carbon stock on different land use changes in the watershed Antsokia Gemza Woreda N/Shewa Zone, Ethiopia and to assess the relationships between soil organic carbon and land use land cover change in the watershed using Land Sat images, forest, agriculture and grazing land were identified. Undisturbed soil samples were taken from1m by1m plots randomly for each land use type from 0-15 cm and 15-30 cm soil depths for soil carbon, CEC, Soil bulk density, pH and soil carbon were determined using standard laboratory procedures; SOC was calculated for each land use using recommended standard formulas. The result showed that the forest area coverage showed an increasing trend as compared to agriculture and open grazing land uses. In forest land the total organic matter and CEC were high and the soil bulk density was low as compared to the other land use types. The highest soil SOC (8.99 Mg ha-1) was recorded in unchanged forest land use, and the lowest SOC (5.78 Mg ha-1) was obtained in the continuous agriculture land use. . Thus, based on the findings of the study, further studies on the drivers of land use and land cover change as well as integrated soil water, and forest management practices are recommended to increase or at least to maintain the soil organic carbon stock and related soil properties in the studied watershed.