The effect of human disturbance on tree species composition and demographic structure in Kalinzu Forest Reserve, Uganda

摘要

Tree abundance and species composition m the mechanically logged, intensively pitsawn and minimally disturbed areas of Kalinzu Forest Reserve were determined. The spatial and diameter size-class distribution of ten selected tree species representing pioneer, secondary colonizer, understorey, canopy, dominant and endangered species were also assessed. The species were: Musanga ko-errerae, Trema orientahs, Funtumm afncana, Strombosia schefflen, Oxyansus specwsus, Pannan excelsa, Tabernaemontana hol-stu, Newtoma buchanami, Lovoa swynnertonu and Entan-drophragma angolense. The mean stem density of all trees >=0.5 m in height was 2809.1 per hectare and 150 species were enumerated in the three forest areas. Most individuals (47.73%) and species (75.0%) were recorded in the minimally disturbed and least in the mechanically logged areas. Of the selected species, F. afncana was the most abundant (n = 789) and widely distributed in each of the areas. Entandrophragma angolense was the least abundant (n = 63)and most of its individuals (74.6%) were recorded in the minimally disturbed area. Funtumia africana and S. schefflen (subcanopy), 0. speaosus and T. holstn (understorey), N. buchanami (canopy) and P. excelsa (an upper canopy and a climax species of thisforest reserve) had an inverse J-shaped diameter size-class structure while pioneer species (M. leo-errerae and T. orientahs) had a bell-shaped size-class structure.