Abstract:
In the Ethiopian highlands, more than 50% of the land area is covered by Afromontane
vegetation, with dry evergreen Afromontane forests and grassland complex (DAFs) accounting
for the largest coverage, most biodiverse, and centre of endemism. However, these forests have
experienced extensive forest degradation due to various anthropogenic activities. The study sites
belong to DAFs and characterized by rugged and mountainous terrain that have experienced
significant degradation primarily by human-driven factors. In response, the Ethiopia government
has initiated sustainable soil management strategies and vegetation restoration programs over
the past decades to tackle these challenges. Therefore, this study was aimed at evaluating the
role of forest exclosures in enhancing the status of woody species, soil quality, biomass
accumulation, and the land use land cover (LULC) changes and the accompanying ecosystem
services values (ESVs) in the dry evergreen Afromontane forests of the northeastern highlands.
Three forest exclosure treatments, exclosure for ten years (EX10), twenty years (EX20), thirty
years (EX30), and open woodland (OWL) as a control were purposively selected and used to
gather woody species composition and structure, soil properties, and biomass accumulation data
across two slope orientations. The study, further, assessed the impact of land use/land cover
(LULC) changes from 1984 to 2021 on ecosystem service values (ESVs) in the region using
satellite images. The findings showed that sixty-one woody species from 34 families were
identified across the study areas. The study showed the positive influence of exclosures on
density, basal area, and regeneration of woody species. However, no substantial changes were
noted in diameter at breast height (DBH) and most functional traits. Nonetheless, both DBH and
functional traits exhibited a gradual increasing trend with increasing exclosure ages. Similarly,
soil quality improved over forest exclosure ages in that the soil exhibited an increased soil pH,
organic carbon (SOC), total nitrogen (TN), available phosphorous (Av.P), and exchangeable
bases. Six woody species community types were identified across the study sites. The results
also demonstrated elevation and edaphic factors, including sand, soil bulk density, calcium, and
soil pH as the most significant explanatory variables in shaping woody species community
patterns. Accordingly, exclosure areas exhibited higher biomass accumulation and carbon
storage compared with the open woodland area. In addition, structural equation models revealed
DBH as a significant predictor of aboveground biomass. The findings showed a substantial
increase in cultivated land and built-up areas, while forested areas and water bodies experienced
significant declines, especially in the first phase between 1984 and 2001. These changes resulted
in a dramatic decrease in ESVs from 54.4 million USD in the stipulated period. However, the
status of forestland showed a marked improvement in the second phase as a result of the
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implementation of various sustainable forest restoration initiatives in the region. The findings of
the present study highlighted the potential of exclosures-based forest restoration in enhancing
the distribution of woody plant species, improving key indicator species, enriching soil
properties, and fostering biomass accumulation. These findings underscored the urgent need for
integrated land-use policies that prioritize biodiversity conservation and the sustainable
management of ecosystem services amid ongoing land degradation. Furthermore, it calls for the
establishment of comprehensive frameworks to mitigate deforestation and land degradation,
providing a benchmark for assessing the progress toward national forest restoration targets by
2030. Ultimately, such efforts have the potential of dual benefits of improving local livelihoods
while ensuring long-term ecosystem stewardship and resilience