Colobus population dynamics and forest change in a fragmented habitat in Central Ghana.

摘要

This thesis explored how the forest habitat in Boabeng Fiema Monkey Sanctuary (BFMS) and surrounding forest fragments has changed in the recent past. It also explored the vegetation dynamics of the core forest of BFMS and the spatial attributes (fragment size and isolation distance) and vegetation characteristics of the forest fragments that predict the abundance of Colobus vellerosus, a threatened primate endemic to the Upper Guinea Forest Block. Field work took place between 2005 and 2007 (May-Aug., 2005, and 2006, and May-Sept., 2007). Changes in the forest were assessed though interviews with local informants, aerial photograph and satellite imagery information. The vegetation characteristics were assessed using plot-based surveys. Data for the core forest of Boabeng was compared with data collected in 2000 by T. L. Saj. The colobus population was censused using a "complete count". The multiple layer canopy of the forest has decreased in all fragments. The only part of these forests that is protected, the core forest of BFMS, actually showed an increase in tree basal area and tree species richness over a seven-year period (2000-2007). Colobus food trees and non-food trees significantly increased in density over the same seven-year period. There was no change in the ecological guilds of tree species except for shade bearers. The most important variables that positively predicted the presence and abundance of colobus in fragments were multiple layer canopy, fragment size and isolation distance. C. vellerosus preferred relatively large forest fragments with complex forest structure and high tree species richness. The forest fragment must also be relatively closer to the source (Boabeng) and have a large vegetated area.