The Relationship between the Edge Density of the Forest Fragments and the Tree Species Richness in the Detached Fragments of Kakamega Forest.

Abstract

Purpose: The theoretical approach guiding this study was based on the Island Biogeography Theory. The purpose of this study was to assess the influence of the edge density of the forest fragments on tree species richness. Methodology: The study adopted a cross-sectional correlational research design. Proportionate random sampling was used. A sample of 30 plots each measuring 2m by 2m was established randomly in the fragments (0-200m from the edge towards the interior);Malava: Kisere: Ikuywa in that order for field sampling and measurements. Data was collected using tools such as measuring tapes,metre rule,GPS 64s Garmain and suunto inclinometer. A total of 39 species of trees were recorded from the three fragments with Funtumia africana being recorded as the most abundant species. Findings: The findings show 83%, 85%, and 92% variation of tree species richness in. Malava (r2 = 0.83), Kisere (r2 = 0.85) and Ikuywa (r2 = 0.92) in that order can be explained by the edge density of the fragments. The edge density also explained 87%, 94% and 94% variation of tree species relative abundance in Malava (r2 = 0.87), Kisere (r2 = 0.94) and Ikuywa (r2 = 0.94) in that order. Unique Contributor to Theory, Policy and Practice: It was concluded that tree species richness and tree species abundance in the detached portions of Kakamega forest were dominantly influenced by forest fragment total edge length and fragment edge density. For us to conserve more tree species we recommend maintenance of the total edge length of the fragments above 15km with edge density (3.413.79m\m2) in order to maintain high tree species richness and tree species relative abundance.