Land snail diversity in post extraction secondary forest reserves in Edo State, Nigeria

摘要

Knowledge of the fauna of tropical lowland rainforest is urgently necessary because of the high rate of biodiversity loss and global extinction of species as a result of deforestation. We studied land molluscs species richness and diversity in four heavily degraded secondary forest reserves and one old-growth forest reserve in Edo State, Nigeria using a combination of direct fixed-time search and litter-sieving techniques in twelve plots of 400m2 each per reserve. A total of 43 species and 2570 individuals were collected from all the reserves. Local species richness ranged from 19 to 39 species while number of specimens from 203 to 971. Molluscan species richness and diversity is significantly higher in the old-growth forest than in the disturbed forest reserves. Land molluscs family composition was similar in all the forests with respect to the common and wide-ranging species while rare and narrow-range species are restricted to the old-growth forest in Okomu. The carnivorous streptaxids and detritivorous subulinids dominate species richness and abundance respectively in all the sites. Species turnover is moderately high within and between the forest reserves indicating the uniqueness of the faunal composition of each forest and the need for adequate protection.