Terrestrial Mollusc Species Richness and Diversity in Omo Forest Reserve, Ogun State, Nigeria

Christopher Omamoke Oke

doi:10.5733/afin.054.0106

Abstract

The terrestrial mollusc species richness and diversity in Omo Forest Reserve, Ogun State, Nigeria, was studied using a combination of direct search and leaf-litter sieving techniques. In total, 28 species and 639 individuals in 7 molluscan families were collected from 17 plots of 400 m2 each. Species richness varied from 3 to 14 (mean 8.59) and the number of individuals from 8 to 67 (mean 37.59) per plot. Species richness was dominated by the carnivorous Streptaxidae (36%) and herbivorous Subulinidae (32%), and numerical abundance by the Subulinidae (56%) and Streptaxidae (32%). The most abundant species was the large subulinid, Subulona pattalus, contributing almost 25% of the total number of individuals. Terrestrial molluscs with small populations and narrow distributional ranges are at great risk of local extinction if forest destruction continues unabated. Studies on the molluscan diversity in Omo Forest Reserve will assist in producing an inventory for biodiversity conservation management in Nigeria.

Highlights

Knowledge of the biodiversity in different ecosystems in tropical rainforest is urgently needed, given the high rate of deforestation and species loss as a result of anthropogenic activities
Omo Forest Reserve is one of such reserves seriously threatened by conversion to plantations of arable and cash crops (Persson & Warner 2003; Ojo 2004), with serious consequences for the biodiversity
Previous studies on biodiversity of the reserve focused on large vertebrates (Johansen 1994; Persson & Warner 2003), and little is known about the numerous invertebrates that constitute the majority of the fauna

Summary

Introduction

Knowledge of the biodiversity in different ecosystems in tropical rainforest is urgently needed, given the high rate of deforestation and species loss as a result of anthropogenic activities. Omo Forest Reserve is one of such reserves seriously threatened by conversion to plantations of arable and cash crops (Persson & Warner 2003; Ojo 2004), with serious consequences for the biodiversity. Omo Forest Reserve is one of six large contiguous forest reserves in Ogun State, south-western Nigeria, established to protect the biodiversity of the region (Persson & Warner 2003). The reserve is one of the few remaining habitats with old-growth tropical rainforest in Ogun State and is severely threatened by logging, poaching and plantation agriculture. Previous studies on biodiversity of the reserve focused on large vertebrates (Johansen 1994; Persson & Warner 2003), and little is known about the numerous invertebrates that constitute the majority of the fauna

Methods

Results

Conclusion