Mapping species distribution and estimating population abundance of dominant forest tree species in Ghana: implications for conservation prioritization

Understanding the spatial distribution and abundance of tree species is critical for the conservation of biodiversity in Ghana’s rapidly declining forests. This study applied Species Distribution Models (SDMs) to assess habitat suitability, abundance patterns, species richness, and conservation gaps of three dominant tree species, Napoleonaea leonensis, Myrianthus serratus, and Penianthus patulinervis, within the semi-deciduous and evergreen humid forest zones of Ghana. Tree occurrence records were compiled from the Global Biodiversity Information Facility (GBIF) database and used as input data for the modeling. Environmental variables, including bioclimatic variables, land cover, topography, and soil properties, were obtained from various online platforms. Habitat suitability was modeled for all three dominant species using the MaxEnt algorithm after correlation and Variable Inflation Factor (VIF) filtering to minimize collinearity. Zero-inflated Poisson (ZIP) models were used to estimate the abundance, while species richness was derived from stack suitability and abundance predictions. MaxEnt suitability models performed strongly across species. Area under Curve (AUC) ranged 0.93–0.96 for Myrianthus serratus and Napoleonaea leonensis. Threshold-based metrics were also high (Kappa: Napoleonaea leonensis 0.72, Myrianthus serratus 0.74, Penianthus patulinervis 0.82; True Skill Statistics (TSS): Napoleonaea leonensis 0.76, Myrianthus serratus 0.85, Penianthus patulinervis 0.85). Abundance models showed good explanatory power (Pseudo-R²: Napoleonaea leonensis 0.283, Myrianthus serratus 0.475, Penianthus patulinervis 0.632; Akaike Information Criterion (AIC) 484.14, 335.73, and 185.87, respectively). Species richness indicated stronger values inside Protected Area (PAs) than outside (mean richness 0.102 inside vs. 0.019 outside). The composite conservation index delineated 23,536,682 ha of hotspot areas with 6,984,6670 ha (30 %) within PAs, highlighting protection gaps in unprotected forest areas. By integrating suitability, abundance, and richness, this study provides an evidence-based framework to guide prioritization and strengthen forest management activities in Ghana.