Diversity of vascular plants on Ssese islands in Lake Victoria, central Uganda

Abstract

Diversity and distribution of trees [‡5 cm diameter at breast height (dbh)], shrubs and herbs was assessed in thirty 0.05-ha (10 · 50 m) plots of a tropical high forest in the Ssese islands of Lake Victoria, central Uganda. The aim was to determine the floristic richness and composition of the forests. We recorded 179 species belonging to 70 families and 146 genera. Of these, nine families had five species or more. Rubiaceae was the richest with fourteen species followed by Euphorbiaceae (thirteen), Apocynaceae (ten) and Moraceae (nine). The majority of the families (35) were represented by one species each. Fifty-eight herbaceous species, 39 lianas, ten shrubs and 72 species of trees were recorded. The commonest species recorded in the forest included: Uapaca guineensis Mull. Arg., Tabernaemontana pachysiphon Stapf., and Aframomum luteoalbum (K Schum.) K. Schum. Among the rare species encountered were Ficus densistipulata De Willd., Englerophytum oblanceolatum (S. Moore) Pennington, and Afromomum zambeziacum (Bak.) K. Schum. The present study has shown that the Ssese islands are floristically rich in species and compare well with other mainland forests. Species richness, rarity and uniqueness of habitats can be considered as approaches in the prioritization of conservation sites within the fragmented forests of Ssese islands.