Exploring the Influence of Slope Gradient on Tree Species Richness and Forest Structure
Abraham Mahari *
Cuttington University, Liberia.
Clinton G. Blasin
Cuttington University, Liberia.
Aberash Bekele
Jimma University, Ethiopia.
Anthony T. Watson
University of Twente, Enschede, Netherlands.
*Author to whom correspondence should be addressed.
Abstract
Slope gradient is a critical environment factor influencing the abundance, distribution and diversity of vegetation. The objective of this study was to exploring the influence of slope gradient on tree species richness and forest structure in Kpatawee forest, Liberia. Tree diameter was measured at breast height for species more than 5 cm in diameter and over 3 m in height. Tree species diversity was analyzed using Shannon diversity index (Hˈ). Basal area (BA) which is the cross-sectional area of tree stems was measured through the diameter at breast height that is 1.3 m above ground level. Results showed that a total of 26 tree species were identified from the total sampling area (0.36 ha). The three richest families: Moraceae, Rutaceae and Euphorbiaceae appear to be well represented in the Kpatawee forest. These families become outnumbered in the herbaceous except for the Rutaceae family, which is ranked second. This is mainly due to their adaptation potential to wider agro-ecologies. Tree species richness was higher in the lower altitude. High species abundance was recorded in the lower altitude followed by the middle and upper. The lowest Shannon diversity index value (H' = 1.85) and the highest value (H' = 2.28) were recorded in the upper, and the lower altitudes, respectively. Despite their values, the biodiversity did not vary greatly from altitude to altitude. Diameter class distribution showed that more species were in the lower diameter classes and decreased gradually towards the higher classes. It is recommended that further studies on the entire Kpatawee forest is needed to fully understand the species richness in the forest.
Keywords: Biodiversity patterns, Shannon diversity index, slope gradient, soil quality, species richness
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References
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