Effect of catenary differentiation on vegetation in Obung forest, Cross River State, Nigeria

The paper examined catenary differentiation of vegetation in Obung Forest, Cross River State of Nigeria. Specifically, it examined the effect of topographic variation on vegetation composition from the upper to the lower slope of the catena. Vegetation data basically tree density, tree species composition, family composition, stem diameter (dbh) and species dominance was obtained from 60 quadrats of 20m by 20m established across the three sections of the catena. Results showed that the number of trees encountered across the catena varied significantly, with the upper slope recording a high stand density of 349, followed by the lower slope of 298, then the middle slope of 243. This difference in stand density was attributed to topographic positions along the catena. Also, mean dbh of trees and basal area varied significantly. The Shannon-Weiner's Index equally varied with the lower slope (2.86) being most diverse and richest than other sections of the catena – upper slope (2.62) and middle slope (2.53). Elaeis guineensis, Terminelia superba and Ficus exasperate were the most ecologically dominant species across the catena. In the upper slope, Khaya guineensis was most dominant, in the middle slope, Elaeis guineensis was, while the most ecologically dominant species in the lower slope was Anthocleista vogelii. The study however advised that to conserve this species-rich ecosystem, the wanton destruction of the forest vegetation especially for fuel wood harvesting and illegal logging activities should be checked.