Ecology and Determinants of a Tropical Rainforest Landscape

Abstract

Tropical ecosystems are bio-diverse ecosystems that differ according to varied environmental features. This work assessed the tree diversity and environmental variables that define a rainforest ecosystem in southeast Nigeria. 30 forest plots were used to identify trees ≥ 10 cm (DBH measured at 130 cm). Soil samples were collected up to 30 cm deep at four edges and middle of each plot, and bulked for analysis. The survey recorded a total of 2414 trees that belonged to 102 species and 32 families. Shannon-Wiener’s diversity index (H’) of 3.67, Inverse Simpson’s index (C) of 1.06, species evenness of 0.79 and Margalef’s index of species richness (M) of 12.97 were recorded. Fabaceae family recorded the highest number (1037) of individual tree (being 43% of total) observations, while Burseraceae had the least number (1). Species abundance status showed 2.9% of species as “Abundant”, 73.5% as “Endangered”, 2.9% as “Frequent” and 20.6% of species as “Rare”. Soil variables namely phosphorus, magnesium, potassium, particle sizes (sand, silt and clay), CEC, calcium, pH, and aluminium, influenced the distribution of the vegetation in decreasing order. Edaphic factors (soil) determined the distribution of tree stems, growth and abundance of the species within the region. Efforts on conserving the ecosystem along environmental gradients and according to species status and indices are advocated.