Abstract

This study investigated the effect of disturbance on the biodiversity of a tropical rainforest. Gap sizes, their distribution and the causal factors were evaluated in the 50 ha Korup Forest Dynamics Plot (KFDP). The regeneration of species was evaluated in the gaps of KFDP, Isangele roadside gaps and its adjoining closed forest. It was observed that gaps make up to 0.1% of the KFDP, and their distribution was clumped. The rocky and higher elevation had the highest number of gaps while the lowest part of the plot had the least. Out of the 303 gaps found in KFDP, 41.3% of these were as a result of tree snapping and the species Oubanguia alata was highly affected, while dead standing caused the least number of gaps (0.7%). Wind throw gaps had the largest sizes (143.88 m²) and the tree species Protomegabaria stapfiana was highly affected by this causal factor. Simpson diversity index of plant species at Isangele roadside was high (0.96) when compared to Isangele closed forest (0.92) and KFDP gaps (0.66) plots. Sørensen’s similarity index of the Isangele road and closed forest was 0.88. Forest gaps may contribute to the maintenance of high species diversity which is significant in forest ecosystem management.

Key words: Causal factors, diversity index, gap sizes, closed forest, similarity index.