Woody species diversity and dispersal dynamics in Biyo Forest, Central Ethiopia: a conservation perspective

Abstract

Seed dispersal shapes species composition, regeneration, and long-term resilience of dry Afromontane forests. In Ethiopia, there is limited information on how woody species disperse and recruit. Biyo Forest, a protected exclosure in central Ethiopia, offers an opportunity to study how different dispersal methods shape forest structure and inform conservation efforts. This study looked at the types of woody species present, their population structure, regeneration status, and how they are dispersed to better understand what supports forest sustainability. Woody species were surveyed along seven transects, using 28 plots measuring 20 × 20 m, with nested 2 × 2 m subplots. GPS randomization made sure the transects were placed without bias. Plants were grouped as seedlings, saplings, or mature based on their height and diameter. Importance Value Index (IVI), Shannon diversity, basal area dominance (RDO), regeneration ratios, and species dominance were computed. Dispersal syndromes were assigned using fruit and seed features and regional plant guides. Statistical analyses were performed using ANOVA, Kruskal–Wallis, correlations, regression, and PCA to explore links between dispersal types, IVI, and regeneration. 27 woody species from 15 families were recorded, with Fabaceae dominating. Species diversity was moderate (H′ = 2.84). Endozoochory was the dominant dispersal mode (48.15%), followed by anemochory (22.22%) and autochory (18.52%). Species density strongly predicted IVI ( r = 0.92), and PCA revealed that endozoochorous species clustered with high ecological importance. Basal area dominance and IVI-based clustering identified four species (e.g., Ficus sycomorus , Vachellia sieberiana ) with regeneration failure, while pioneers such as Dodonaea angustifolia showed strong recruitment. Overall, Biyo Forest recorded 1288.4 seedlings/ha, 836.6 saplings/ha, and 1013.4 mature individuals. Biyo Forest is dominated by animal-dispersed species, emphasizing frugivores’ role in forest dynamics. Several species face regeneration bottlenecks, indicating the need for targeted conservation, protection of keystone species, and maintenance of frugivore networks to sustain ecological resilience. Not applicable.