Impacts of longterm conservation measures on ecosystem services in Northwest Ethiopia

A Soil Conservation Research Program (SCRP) has been on-going in Anjeni Watershed, Amhara Region, Ethiopia since the 1980s, focussing particularly on soil-based, graded fanya juu terraces. This study was carried out to examine the long-term impacts of these soil and water conservation measures in improving ecosystem services. A comparative analysis was made with a non-treated 100 ha adjacent watershed (Zikrie). The Revised Universal Soil Loss Equation (RUSLE) was used in a geographic information system (GIS) to quantify soil loss. Representative soil samples were taken 30 cm deep soil pits in the loss and deposition zones in the terraced Anjeni and topo-sequential soil samples on both watersheds. Laboratory analysis was carried out at the National Soil Testing Laboratory (NSTL) of Ethiopia. Soil texture, pH and OC were analyzed for the 91 soil samples. A GIS analysis of the RUSLE factors was made on a 5 m grid cell basis. The mean annual soil loss rate in Anjeni was estimated to be 37 t ha^-1 yr^-1, while that of the adjacent non-conserved Zikrie was 45 t ha^-1 yr^-1. The total estimated soil loss in Anjeni watershed was 4214 t yr^-1. River valleys in the Anjeni watershed had the maximum mean annual estimated soil loss hazard (86 t ha^-1 yr^-1). Cultivated land had medium mean annual estimated soil loss (44 t ha^-1 yr^-1) due to the soil conservation works. Supporting the soil-based graded fanya juu terraces with biological soil conservation measures is important for the stability of the ecosystem.