This paper investigated the influence of forest tenure on vegetation characteristics for selected forests under private, District Forestry Services of local governments and National Forestry Authority in central Uganda. Two hundred and twelve plant species in 65 families and 168 genera were recorded. The family Moraceae was the most species rich in Central Forest Reserves (CFRs), while Euphorbiaceae were the most species rich in private forests and Local Forest Reserves (LFRs), respectively. There were 174 species in CFRs, 144 species in LFRs and 112 species in private forests. Our findings indicated a remarkable shift in floristic composition among the studied forests from Albizia-Piptadeniastrum-Celtis species primary dominance by 1964 report to current secondary and colonising species of Trilepisiummadagascariensis-Funtumia africana-Pseudospondias macrocarpa and Macaranga schweinfurthii. Diversity measured by two indices, i.e., the Shannon diversity and evenness for the different growth forms differed significantly among the forest ownership categories. The CFRs were the most diverse for the trees, while the private forests were the most diverse for the ground flora species. Plant species richness also expressed by the two indices: Species density and Margalef's diversity index followed the same trend, with CFRs being the most species rich for the trees, followed by the private forests and LFRs. The population structure characteristics i.e. stem densities, mean DBH and basal area of saplings and trees were higher in private forests than CFRs and LFRs. Diameter size for all species combined followed the inverse J-shape, typical of mixed-age stands. LFRs and CFRs were highly affected by human disturbances which may be an indicator that government agencies are not as much in control as private forest owners. We found that the composition and distribution of species in the Mpigi forests is complex because it is influenced by two conflicting factors i.e. ecological stability versus human disturbances. We conclude that human activities influenced by forest tenure reduced plant species diversity and composition at different sites; confirming the argument by common property theorists that open access resources are not compatible with biodiversity conservations. There is thus a need for forest managers to regulate human activities for effective conservation of forests.