Tree gap dynamics and their influence on chimpanzee food tree regeneration in Kalinzu Forest Reserve, south-western Uganda

Abstract

The chimpanzee (Pan troglodytes schweinfurthii) community in Kalinzu Forest Reserve, South Western Uganda is relatively stable and ranks third in the country with a total population density of 1.55 Km-2 compared to Kibale in western Uganda at 2.32 Km -2 and Bugoma at density 1.9 Km-2. This is attributed to sustainable existence of chimpanzee food trees in Kalinzu Forest Reserve. Like many Ugandan forests, Kalinzu Forest Reserve displays a lot of gaps due to timber harvesting and other disturbances, yet it is not clear how the introduced tree gaps affect regeneration of chimpanzee food trees. The objective of this study was to document the effect of forest gap dynamics on regeneration of chimpanzee food trees in a natural rain forest in south-western Uganda. Results indicate occurrence of about 115 gaps, distributed throughout the habitat. The leading causes of forest gaps in both production and research zones of Kalinzu Forest Reserve were tree and/or branch falls (34.8%), charcoal burning (18.3%), gold mining (18.3%), selective logging (15.7%) and other causes (13%). In terms of size, gaps located in the production zone were medium (8.45 - 518.86 m2 ); whereas gaps in the research zone were bigger (13.58 - 855.10 m2 ). Tree regeneration in gaps was much higher than in the forest understory, an indication that gaps favour regeneration of chimpanzee food trees in this forest. Gaps in the production zone regenerated trees faster than their counterparts in the research zone. This study concludes that without human induced disturbance, regeneration of chimpanzee food tree species continues to occur in gaps created by natural causes. It is also clear that with regulated forest use, chimpanzees in Kalinzu may continue to have a sustainable food source.