Floristic composition, structure and regeneration status of trees as affected by agro-climatic variation in the Bale mountains national park, South-eastern Ethiopia

The Bale Mountains National Park (BMNP), situated in the southeast highlands of Ethiopia's Bale eco-region, is a globally recognized hotspot for biodiversity. The devastating rate of habitat degradation across various agro-climatic zones, in spite of its enormous ecological significance, puts many species' survival in jeopardy. This study aims to examine the effects of agro-climatic variation on floristic composition, structure, and explore human-induced factors driving the changes in ecosystem. To gather representative vegetation data, 144 sampling plots spanning 5.76 ha were set up along three altitudinal gradients with four replications. One-way ANOVA was used to compare the mean species composition and structure among agro-climatic zones, and significant differences were reported with p < 0.05. Results showed that mean DBH (49.63 ± 1.34 cm) and species richness (76) of the sub-moist mid highland were found to be significantly higher than in the cool moist mid highlands (44.50 ± 1.42 cm and 31, respectively) and in the cold humid afro-alpine zone (29). The sub-moist mid highland had a significantly higher density of seedlings, saplings, and mature trees than the cool moist mid highlands. Although the mean density and basal area of woody species did not differ significantly (p < 0.05) between the sub-moist mid highland and the cool moist mid highland, the sub-moist mid highland exhibited higher overall values, with 914 stems per hectare and 91.16 m² ha⁻¹, compared to 653 stems per hectare and 79.10 m² ha⁻¹ in the cool moist mid highland. The study concludes that the sub-moist mid highland supports a majority of species and contains trees with bigger space occupancy, and ecologically diverse communities which requires urgent protection measures. Because of the cold humid afro-alpine zone is ecologically delicate, it requires a comprehensive ecological approach to manage natural resource that incorporates ecosystem protection and restoration.