Modelling the Potential Distribution Shifts of Threatened Timber Species Under Climate Change Scenarios in Nigeria: An Original Species Distribution Modelling Approach

Threatened timber species in Nigeria face compounded pressures from overexploitation and climate change, yet projections of future range shifts under climate change are entirely absent from the Nigerian conservation planning literature, representing a critical gap this study addresses with an original methodological contribution. This study modelled current and projected future distributions of 15 threatened Nigerian timber species (including Khaya spp., Entandrophragma spp., Afzelia africana, and Milicia excelsa) under two shared socioeconomic pathway climate scenarios (SSP2-4.5 and SSP4-8.5) at 2050 and 2080 time horizons, using an ensemble species distribution modelling approach. An original multi-algorithm ensemble framework was constructed, combining MaxEnt, Random Forest, BioClim, and GLM models, with Bayesian model averaging used to produce ensemble projections with uncertainty quantification. Predictor variables included 19 CHELSA bioclimatic variables, soil type, topography, and a novel Anthropogenic Disturbance Index derived from land use data. Model performance was assessed by area under the ROC curve and true skill statistic through 5-fold spatial cross-validation. Results showed that all 15 species will experience range contractions under both climate scenarios, with mean projected range loss of 34% (SSP2-4.5, 2050) to 61% (SSP4-8.5, 2080). Northward range shifts were projected for 11 species, but suitable habitat in the north will simultaneously experience increasing aridity. The Jos Plateau emerged as a future range refuge for 8 species under both scenarios. An original Climate Debt Index for threatened timber species is proposed, quantifying the lag between current and future suitable range. The study provides the first climate-integrated conservation planning tool for Nigerian threatened timber species.

Keywords: species distribution modelling, climate change, threatened timber species, range shift, Nigeria