Higher vegetation diversity and stronger forest structure occur in managed zones despite widespread land cover degradation in Ise Forest Reserve Nigeria

The forest ecosystem of Ise Forest Reserve in Nigeria is threatened by land-use conversion and timber exploitation. However, part of the enclave was managed under the Southwest/Niger Delta Forest Project, described as the “managed zone”. This study investigated spatial differences in vegetation condition and temporal patterns of land-cover degradation by integrating systematic field sampling, remote sensing and geographic information technologies. Eleven 25 × 25 m plots were laid along 200 m transects during a field sampling exercise carried out in disturbed and managed zones and were used to test differences in species diversity and structural attributes. In total, 27 species (17 families) were recorded, with Ricinodendron heudelotii achieving the highest frequency ( n = 55) and Diospyros lotus exhibiting the most significant mean height (12.20 ± 0.00 m), canopy cover (18.60 ± 0.00 m), and diameter at breast height, DBH (138.13 ± 0.00 cm). Significant differences ( p < 0.001) in height, DBH, and canopy cover were observed between the disturbed and managed zones. Vegetation diversity was higher in the managed zone than in the disturbed zone. The values of the Shannon–Wiener, Simpson concentration, and Margalef richness indices were higher in the managed zone than in the disturbed zone. The lower rates of farmland expansion and secondary forest loss in the managed zone indicated spatial differences in the severity of land degradation. Since data on the area’s pre-intervention stage for direct comparison were not available, the differences between the managed and disturbed zones could not be attributed solely to the 2021 conservation project and remain subject to review in a long-term evaluation.