Gallery forests versus bosquets: conservation of natural fragments at Lope National Park in central Gabon

Abstract

Human-induced forest fragmentation has been relatively well-studied, however, we know very little about the role of natural fragmentation in sustaining rare or marginal species that could have been lost if the advancement of continuous forest had not been controlled. Between February 2001 and January 2003, we conducted a study on characteristics of natural forest fragments in the mosaic of forests and savannas in the north of Lopé National Park in Central Gabon. We surveyed 61 vegetation plots (0.08 ha each) and compared vegetation characteristics of isolated forest fragments (bosquets) with those of gallery forests. Both shared 39% of all 251 species inventoried. Gallery forests contained 45% plant species on their own, while 16% were encountered only in bosquets. Therefore, bosquets were found to be valuable component of the Lopé landscape worth protecting. In addition, the Shannon-Wienner diversity index (H′) was higher for bosquets neighbouring gallery forests or continuous forests regardless of their sizes because seeds of new plant species were easily dispersed in these bosquets. To protect these gallery forests and bosquets, one of the traditional conservation tools - a controlled savanna burning - should still be used to prevent forest fragments from being engulfed by the expanding continuous forest.