Impact of area closure on woody species diversity and soil physicochemical properties: evidence from Hulberag District, Central Ethiopia

BACKGROUND: Land degradation is a threat to global ecosystems and livelihoods of billions of people. Nearly 85% of Ethiopia's land is degraded, costing more than USD 4.3 billion per year. Area closures for excluding human and livestock disturbances have been widely adopted as a restoration strategy for degraded lands to enable natural regeneration. However, integrated ecological and socio-economic assessments are scarce in the Siltie Zone of Central Ethiopia and evidence-based interventions are limited. METHODS: A comparative study design was used in the study area of Hulberag District, to assess 14-years-long area closures and adjacent open grazing lands. Data collection comprised vegetation surveys, physicochemical analyses of soils at different soil depths and household questionnaires. Statistical analysis was performed by ANOVA and post-hoc Tukey's HSD tests to compare land-use types and topographic positions. RESULTS: Area closures significantly improved ecosystem metrics. Woody species richness increased by 200%, stem density increased by 154%, and Shannon diversity was significantly higher than in open grazing lands. Soil organic carbon increased by 50%, available phosphorus by 33%, and cation exchange capacity by 25%. Bulk density decreased by 19%, indicating reduced soil compaction and improved soil quality. The greatest improvements occurred on lower slopes. Surveys revealed strong community support, with 79.8% of respondents identifying livestock fodder as the primary benefit and 53.1% associating area closures with increased crop yields through improved erosion control. CONCLUSIONS: Area closure represents an effective, low-cost intervention for restoring degraded semi-arid ecosystems in Ethiopia, promoting native woody vegetation recovery and enhancing soil fertility while providing tangible livelihood benefits. For long-term success, adaptive co-management frameworks that integrate clear resource-use guidelines, equitable benefit-sharing, and alignment with broader watershed conservation strategies are recommended.