This paper synthesizes the spatial and temporal relationship between forest cover and water, as well as its implications for food security in the northwestern highlands of Ethiopia. Different studies addressing the topic of land cover and hydrology have been reviewed. Analyses of 20–40 year long time series showed little and inconsistent relationships between forest cover change and hydrology on meso-scale (100–1000km2) watersheds. Spatial studies, however, showed stronger relationships between land cover and low flow features such as grasslands and woodlands. Interviews with local communities suggested land cover change impacts are more pronounced at smaller scale (<100km2) watersheds; which is consistent with observational studies on small scale watersheds and farm level plots. The stronger relationships between forests and hydrology at smaller scales suggests land management policies should be oriented to farm level conditions, where water is vital for the food security of subsistence farmers who comprise 86% of the population in the highlands.

The Ecosystem Restoration Project (ERP) is a critical and urgent practice to achieve the land degradation neutrality (LDN) targets. However, an insufficient understanding of the balance between contrasting sectors of the food-water-ecosystem nexus results in ineffectiveness in supporting complex environmental management (CEM), leading to undesirable ERP failures. The Ordos Plateau case identified the nexus evolution and the non-linear interactions between sectors, which were expected to support adaptive strategy formulations for CEM and achieve win-win outcomes. Revegetation in drylands substantially boosted ecosystem restoration, alleviating soil erosion. However, the excessive reliance on returning cropland to woodland and grassland has caused a significant loss of arable and grazing land. During the initial period of ERPs, this exacerbated decline in grain and meat productivity. In addition, aggressive revegetation activities have also reduced runoff yield and depleted soil water resources. Water scarcity is recognized as the most challenging issue in dryland ecosystem restoration, heavily influencing the interactions between sectors and threatening the long-term sustainability of ERPs. To accommodate for regional water carrying capacity, ERPs should adopt and properly allocate the use of suitable plant species with a proven anti-drought capability and high survival ratios without additional human interventions. In addition, the evolution regimes, driving factors, critical thresholds, and complex feedbacks between the nexus sectors should be fully understood to address the water resources constraints and reconcile trade-offs. This would enable the prevention of ecosystem shifts to undesirable failures and inform timely and cost-effective CEM to achieve the LDN targets.