Woody species diversity and regeneration dynamics along environmental and disturbance gradients in a community-managed Afromontane forest, southwest Ethiopia

Tropical montane forests are globally important for biodiversity conservation, carbon storage, and regulation of hydrological and biogeochemical cycles, yet they are increasingly shaped by interacting environmental gradients and human-induced disturbances. In the Eastern Afromontane biodiversity hotspot in southwest Ethiopia, community-managed forests represent a growing governance model intended to reconcile conservation and livelihoods. To date empirical evidence on how disturbance and recovery processes operate within these systems remains limited. In this paper, we examine woody species diversity, forest structure, and regeneration dynamics in the Andaracha Participatory Forest Management (PFM) forest of, with a specific focus on how environmental heterogeneity and disturbance intensity structure forests ecology.

We conducted a field-based ecological assessment using 44 systematically distributed nested plots across 11 forest management units (Gots). Floristic inventories recorded species identity and diameter at breast height (DBH) for all woody species, alongside plot-level regeneration data based on seedling counts. Environmental variables (altitude, slope, canopy cover) and a composite disturbance index integrating logging, grazing, fuelwood extraction, and access trails were recorded. In addition, institutional context was characterised using a PFM engagement score derived from participatory monitoring of annual plan and bylaw enforcement, meeting frequency, forest patrolling, and reporting mechanisms. Multivariate analyses, including hierarchical clustering, principal component analysis (PCA), non-metric multidimensional scaling (NMDS), and PERMANOVA, were used to assess relationships between species composition, regeneration patterns, and environmental-disturbance gradients.

Across the study area, a total of 60 woody species belonging to 38 genera and 28 families were recorded, with Rubiaceae and Euphorbiaceae among the most species-rich families. Forest structure was heterogeneous, with reverse-J DBH distributions at the landscape scale indicating ongoing recruitment, but substantial plot-level variation in size-class structure. Species composition clustered into five distinct community types aligned primarily along altitudinal, slope, and canopy gradients. Regeneration dynamics were highly uneven: more than two-thirds of all seedlings were concentrated in fewer than 10% of the plots, revealing strong spatial patchiness in recovery processes.

Ordination analyses highlighted disturbance intensity and canopy cover as key axes structuring both adult community composition and regeneration assemblages. Moderate disturbance levels were associated with higher species diversity and more balanced regeneration, whereas heavily disturbed and open-canopy plots showed reduced recruitment and greater dominance by disturbance-tolerant taxa. Conversely, steep, high-altitude plots with low disturbance exhibited environmentally filtered regeneration characterised by low diversity but stable species composition. These patterns indicate that woody species composition and regeneration in the Andaracha community-managed forest are shaped not by disturbance alone, but by its interaction with topographic constraints and canopy structure.

Our findings demonstrate that community-managed Afromontane forests can sustain high woody biodiversity and active regeneration, but that recovery is highly spatially uneven and sensitive to ecological thresholds of disturbance. These findings underscore the importance of site-specific, ecologically informed management strategies to enhance regeneration resilience in tropical montane forests undergoing rapid socio-ecological change.