Impact of exotic plantations and harvesting methods on the regeneration of indigenous tree species in Kibale forest, Uganda

Abstract

AbstractExotic plantations of Cupressus lusitanica Mill, Pinus caribaea Morolet and Eucalyptus species were established in the grasslands of Kibale Forest Reserve during the late 1960s and early 1970s. Thirty years later (1995), plantation harvesting began based on pitsawing and sawmilling methods. This study aimed at assessing the effect of logging exotic plantations and the methods of harvesting on the young regeneration of indigenous tree species. Sample plots were randomly established in the plantations in the sawmilled and pitsawn areas. All tree stems over 1.3 m in height were identified, diameter at 1.3 m and height measured. The plantations showed a total of 91 tree species with the logged C. lusitanica and P. caribaea areas exhibiting higher number of tree species (79 and 78 respectively) than Eucalyptus (55). The pioneer, colonizing and secondary forest species contributed significantly to the density of regeneration in logged C. lusitanica (2170.5 t ha−1), P. caribaea (2309.2 t ha−1) and eucalyptus (1513.7 t ha−1) areas. The Climax species were still very low and the species very scanty. While pitsawing and sawmilling seem to have had little influence on species richness (Ps = 63, Sm = 65), pitsawing encouraged higher tree regeneration densities (ps = 2223.5 t ha−1) than sawmilling (Sm = 1822 t ha−1). Deductively, C. lusitanica and P. caribaea plantations could be used economically in afforestation, reforestation and accelerated natural forest colonization.