TREE SPECIES DIVERSITY IN A NIGERIAN MONTANE FOREST ECOSYSTEM AND ADJACENT FRAGMENTED FORESTS

Abstract

The study was conducted at Ngel Nyaki Forest Reserve to capture the tree species composition, diversity and richness in a Nigerian montane forest ecosystem, and to compare same between a protected natural forest - Main Forest (MF), and unprotected forest fragments (A, B, and C) within the buffer zone. Vegetation sampling was carried out using the Point-Centred Quarter (PCQ) method. Alpha diversity was measured using both Simpson and Shannon-Wiener indices while similarity or otherwise dissimilarity in species composition between the sites was measured using Sorenson’s index. A total of 22 tree species were encountered in MF while 19, 18, 17 species were encountered in fragments A, B, and C respectively. Only 5, 3 and 4 tree species were common to MF and A, MF and B, and MF and C, respectively. A total of 10 tree species were common to fragments A and B, while 11 species were common to each of fragments A and C and B and C. Tree density (per hectare) was higher in the fragments than MF except for fragment C; though, individuals with larger diameter classes were more in MF. Tree diversity was higher in MF than in the fragments with C being the least diverse. Considering the importance of fragment C as a corridor within a buffer zone, and a source of livelihood to the rural community, the need for its restoration, protection and the introduction of stringent measures to ensure sustainable resource utilization was emphasized.