Population structure, density and natural regeneration of the critically Endangered tree, Boswellia ogadensis, in the Shebele River Valley, Somali Region, Ethiopia

Conserving African dryland forests dominated by Boswellia, Commiphora, Vachellia , and Senegalia species is critical for biodiversity and local livelihoods. Among these, Boswellia ogadensis , a Critically Endangered tree endemic to Ethiopia's Shebelle River Valley, remains poorly understood regarding its population dynamics. We assessed population structure, density, and natural regeneration of B. ogadensis across 96 systematically sampled plots (20 m × 20 m) in three community-managed forests (Hul-Kujir, Elo-Oumer, and Marawajiyel) in the Adadale and Gode districts. The population exhibited a top-heavy structure dominated by mature trees (50.7–56.4% of individuals), with relatively uniform stem densities across sites (56.94–65.83 stems ha⁻¹) but consistently underrepresented seedling (22.8–28.3%) and sapling (19.3–22.1%) fractions, deviating from the typical inverted-J distribution and signaling a critical regeneration bottleneck. Two-Way Multivariate analysis of variance showed that livestock grazing significantly suppressed natural regeneration (p < 0.0001), with seedling establishment disproportionately affected: densities varied by site under low grazing but collapsed to near-zero (0.00–0.17 stems plot⁻¹) under high grazing, whereas sapling density, though also reduced under heavy grazing, remained comparatively higher and did not vary by site, suggesting current sapling cohorts largely reflect past recruitment rather than ongoing establishment. Field observations further implicated unsustainable resin tapping, land clearance, hyper-arid conditions, and invasion by Prosopis juliflora as compounding stressors, though their relative contributions warrant further quantitative investigation. Urgent interventions, including seasonal grazing exclusions, seedling protection, invasive species control, community-led sustainable tapping, and strengthened local governance, are needed to secure the long-term persistence of this keystone species.