Modelling Climate Change Impacts on Forest Ecosystem Service Provisioning in Nigeria Under Multiple Emission Scenarios

The projected effects of climate change on forest ecosystem service provisioning in Nigeria have significant implications for food security, water supply, biodiversity conservation, and climate regulation, yet integrated biophysical modelling of these impacts under multiple emission scenarios has not been conducted at the national scale. This study employs an ensemble modelling approach to project changes in four priority forest ecosystem services (above-ground carbon storage, water yield regulation, biodiversity habitat quality, and non-timber forest product provisioning potential) across Nigeria's forest ecosystems under three shared socioeconomic pathway scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) to 2070. Climate projections were downscaled from CMIP6 multi-model ensembles at 10-kilometre resolution. Dynamic global vegetation modelling using LPJ-GUESS simulated biome shifts and forest biomass trajectories under each scenario. Hydrological ecosystem service changes were estimated using the InVEST water yield module. Biodiversity habitat quality was projected using stacked species distribution models for 185 forest-specialist species. Under moderate warming (SSP2-4.5), above-ground carbon stocks in the Guinea-Congolian rainforest zone decline by 18% by 2070, while water yield increases in some upland areas and decreases in southern lowlands. Under high-emission scenarios, forest cover retreats northward with severe biodiversity consequences in the Sudan-Sahel transition zone. Non-timber forest product provisioning shows the greatest sensitivity to rainfall variability in forest-dependent communities. The study identifies spatial refugia where multiple ecosystem service co-benefits are maintained even under high-emission scenarios, informing climate-smart forest conservation prioritisation. Keywords: climate change, ecosystem services, forest modelling, Nigeria, shared socioeconomic pathways