Diversity, distribution, and conservation status of forest tree species in cross river state, Nigeria

Tree species diversity plays a central or decisive function in ecosystem operations, delivering palpable and impalpable advantages. The periodical evaluation of forest trees is absolutely necessary for the management and conservation goals. Our study employed the modified Whittaker sampling method to survey the diversity and distribution of tree species in 22 forested sites across the northern, central, and southern geographical zones of Cross River State, Nigeria. Only tree species (dbh ≥ 10 cm) present in our sampled plots were identified and recorded. The conservation status of identified forest tree species was checked using the IUCN red list categories and Criteria 2021: ver. 3.3.1-second edition. Field studies were undertaken from April 2019 – October 2020. A total of 197, 249, and 229 tree species belonging to 49, 50 and 49 families were recorded in the northern, central and southern geographical zones, respectively. A total of 403 tree species belonging to 65 families was recorded across the study area, of which 55, 79 and 78 tree species were localized to the northern, central and southern geographical zones, respectively. The Fabaceae was the most dominant family (64 species) while twenty families had one species each. The Cross River National Park (CRNP), Okwangwo Division had the highest number of tree species (171) while Adiabo community forest had the lowest (26). The CRNP, Okwangwo Division exhibited the highest species richness (11.39) and diversity index (4.75) while Adiabo community had the lowest species richness (4.47) and diversity index (1.14). The Least Concern conservation status had the highest number of species (226) while the Critically Endangered and Data Deficient had the lowest (1 each). Our findings will assist accord policymakers or stakeholders the information obligatory for implementing a forestry blueprint and plan of action or scheme in Cross River State, Nigeria.