SEEDLING SURVIVAL AND GROWTH OF 4 SHOREA SPECIES IN A SRI-LANKAN RAIN-FOREST

In this study four species of the genus Shorea section Doona were inve stigated. All occur together as canopy trees in the Sinaraja rainfores t of south-west Sri Lanka. Partitioning of the regeneration niche can be one explanation for the co-existence of ecologically similar canopy tree species within a forest. Seedlings were planted in plots located in five zones that represent a range of forest groundstorey microenvi ronments found adjacent to and across canopy openings of three sites - valley, midslope, ridgetop. Experiments were designed to monitor surv ival and growth of planted seedlings for two years. At the end of two years percentage survival was calculated, height increment recorded an d destructive samples taken to measure dry mass gain of root, stem and leaves. Comparisons were made of establishment and growth performance of seedlings planted in the different plots and sites. Results demons trated clear differences in survival and growth among species. These d ifferences appeared related to availability of soil moisture and groun dstorey radiation regimes. Disturbance patterns that determine species co-existence are suggested.