Vegetation Assessment along Disturbance Gradients in Yankari Game Reserve, Bauchi State

Yankari Game Reserve in Bauchi State, North East Nigeria, is one of Nigeria's premier wildlife conservation areas, and understanding vegetation responses to disturbance gradients within and around the reserve is essential for adaptive management. This study assessed vegetation composition, structure, and diversity along disturbance gradients ranging from undisturbed reserve interior to the heavily disturbed reserve boundary and adjacent farmland. Vegetation plots (25m x 25m) were established at 15 systematically placed stations across three disturbance levels: interior, boundary, and farmland fringe. All plant species, stem density, and canopy cover were recorded. Disturbance was quantified using a composite disturbance index comprising human footprint, livestock impact, and fire frequency scores. Species richness declined significantly from reserve interior (mean 43 species per plot) to farmland fringe (mean 18 species per plot). Shannon-Wiener diversity index declined from 3.24 to 1.71 across the gradient. Characteristic woodland species including Anogeissus leiocarpus and Combretum adenogonium dominated interior plots, while boundary and fringe vegetation was characterised by ruderal and pioneer species such as Cassia sieberiana and Securinega virosa. Composite disturbance index correlated negatively with species diversity (r = -0.84, p < 0.01). Four globally threatened species were recorded only in interior plots. The study concludes that vegetation condition in Yankari Game Reserve degrades rapidly with increasing disturbance, and recommends a formalised buffer zone management plan with community participation to reduce boundary pressure. Keywords: vegetation assessment, disturbance gradient, Yankari Game Reserve, Bauchi State, biodiversity