From degradation to restoration: addressing the environmental challenges in the Ethiopian highlands.

The highlands of Ethiopia are a well-known example of severely degraded landscapes in Africa, with concerns for food shortages. The Ethiopian Highlands Reclamation Study (EHRS) has documented the rates, underlying causes, and costs of land degradation, which resulted in intensive conservation and restoration efforts over the past decades. Despite the extensive effort devoted to the problem, the actual extent of conservation and restoration work has not been adequately quantified and documented. This prompted a crucial inquiry into the current environmental status to quantify the biophysical impacts of 20 years of Soil and Water Conservation (SWC) and restoration in the Ethiopian highlands. Quantitative data on the extent of conservation and restoration measures implemented were generated through a systematic analysis of metadata obtained from Ethiopia's watershed database, maintained by the Ministry of Agriculture (MoA), with field validation in 56 sample watersheds. The analysis of change in land use/land cover (LU/LC) and the normalized difference vegetation index (NDVI) was employed to examine the extent of vegetation restoration and forest cover change in the Ethiopian highlands from 2002 to 2022. The Google Earth Engine (GEE) was utilized for acquiring and processing satellite image data. The potential soil loss across different land-use types was quantified using the InVEST-SDR (Integrated Valuation of Ecosystem Services and Trade-offs Sediment Delivery Ratio) model, combined with other biophysical data disaggregated by physiographic regions to capture diversities in the biophysical settings. Erosivity, erodibility, digital elevation model, vegetation cover, and land management factors were the input data used for the InVEST-SDR model. The results showed that Ethiopia has achieved unprecedented progress in reversing land degradation over the past two decades, with nearly 28 million hectares of degraded landscapes treated through community mobilization and flagship programs. The forest area has increased from about 2.6 million ha in 2002 to 5.9 million ha in 2022. Conversely, the total area of bare land was reduced from 2.5 million hectares in 2002 to 830,000 hectares in 2022. Similarly, the average soil erosion rate on cultivated fields declined from 69 ton/ha in 2002 to 35 ton/ha in 2022, reflecting the cumulative impact of extensive land restoration and soil and water conservation interventions implemented across the Ethiopian highlands. These benefits underscore the effectiveness of combining community-led restoration, bottom-up conservation efforts with top-down policy support. Numerous Sustainable Development Goals, such as Zero Hunger (SDG 2), Climate Action (SDG 13), and Life on Land (SDG 15), can be achieved in part thanks to Ethiopia's experience. Future research should focus on detailed watershed-level studies to study agro-ecological variations in conservation outcomes, conduct cost-benefit analyses of water and soil conservation measures, and implement long-term vegetation monitoring and socio-economic surveys to enhance community-led restoration efforts.