Assessing future climate change impacts on habitat distribution of threatened plant species in the Lower Ouémé Valley Biosphere Reserve (RB-BVO) in Benin

Climate variability and change are among the most significant development challenges currently facing our planet. These phenomena have significant impacts on plant resources including noticeable shifts in phenological stages of plant species and reductions in habitats range. This study examines the effects of future climate change on the distribution of suitable habitats for threatened plant species listed on the International Union for Conservation of Nature (IUCN) Red List within the RB-BVO. The methodological approach involved collecting climate data and species occurrence records. Future climate trends were analyzed using Khronostat 1.01 software and Excel spreadsheets. Additionally, simulations of the potential effects of future climate variability on suitable habitats for these species by 2055 and 2099 under the RCP4.5 scenario were conducted using the MaxEnt model. The results indicate rainfall instability and significant increases in monthly temperatures (2 °C difference between 2020 and the projected peak). These changes will likely extend thermal stress periods within the RB-BVO region, affecting the distribution of habitats for the 16 identified threatened species. These include two Endangered species (Aphania senegalensis and Pterocarpus erinaceus), nine Vulnerable species (Afzelia africana, Albizia ferruginea, Khaya senegalensis, Millettia warneckei, Nesogordonia papaverifera, Pierreodendron kerstingii, Pseudospondias microcarpa, Pterygota macrocarpa, and Ricinodendron heudelotii), and four Near Threatened species (Chrysophyllum albidum, Eucalyptus camaldulensis, Irvingia gabonensis, and Milicia excelsa). Projections for 2055 and 2099 under the RCP4.5 scenario show a reduction in suitable habitats for the conservation of these taxa within the RB-BVO, with habitat losses estimated at 32.55% by 2055 and 44.47% by 2099. The implementation of a management and conservation plan for these threatened species in response to climate instability is therefore essential for the reserve.