This paper assesses the potential of forest plantations in Sri Lanka consisting of teak, mahoganyand two species of eucalyptus, to facilitate the conservation of biodiversity using two taxonomic groups,the plants and birds. Their diversity in plantations at a harvestable age were compared with that of anatural forest. Enumerations of plants and dbh/height measurements were conducted in quadrates, whileavifauna was recorded along transects. Results show that plantation forests supported a reasonably richcommunity of both plants and birds, including natives and endemics. A large proportion of species werecommon to both plantations and natural forests indicating that plantations hold a subset of forest species.The presence of plants of various height and girth classes together with the high diversity and evennessvalues indicate that, although timber plantations are initially established as mono-cultivations, theyfacilitate the colonization of additional species. These findings thus demonstrate that forest plantationscould make a significant contribution towards biodiversity conservation.