Tree mortality in the Kibale Forest, Uganda: A case study of dieback in a tropical rain forest adjacent to exotic conifer plantations

We report the dieback of three out of five unrelated species of rain-forest canopy trees in a very restricted part of the Kibale Forest, W. Uganda that were monitored since 1977. High mortality rates began about 1978 and continued through 1986, reaching levels of 5-50% year-1. Within the restricted area of mortality, all adults of Newtonia buchananii were dead in 1984, while nearly 90% of Lovoa swynnertonii and 45% of Aningeria altissima were dead in 1986. In contrast, Mimusops bagshawei and Celtis africana experienced relatively low (0.5%) and moderate (1.6%) levels of annual mortality, respectively. Regeneration of the seedling and sapling stages was high for all five species, while the pole class was poorly represented. The single most important variable associated with the dieback was downslope proximity to the conifer plantations. Based on this case study, it is strongly recommended that exotic trees, particularly conifers, should not be planted near natural forests in the tropics. Furthermore, those conifer plantations already existing near the natural forests should be harvested in a manner which encourages the regeneration of native trees and shrubs, thereby replacing exotic plantations with indigenous forest. © 1989.

Duke Scholars

Author Thomas T Struhsaker Evolutionary Anthropology