SITE EFFECTS ON SURVIVAL AND GROWTH OF PLANTED "SHOREA CURTISII" IN A LOGGED-OVER HILL FOREST IN PENINSULAR MALAYSIA

We investigated three site effects on the survival and growth of Shorea curtisii trees in an 18-year-old plantation in Bukit Kin ta Forest Reserve, Peninsular Malaysia. Past studies of enrichment planting of S. curtisii indicated poor survival and growth in logged-over hill forests. To improve the planting technique, three site effects, i.e. slope angle, plot size and total basal area of surrounding trees (TBS), were analysed using a general linear mixed model with Bayesian parameter estimation. Plot size (25-900 m²) showed a major effect on survival and diameter at breast height (dbh), subsequently slope angle was supported as a secondary effect by model selection. TBS was shown to have a major effect on total tree height. Slope angle and plot size consistently showed negative and positive effects on all explanatory variables such as survival rate, dbh and total height. In contrast, TBS showed a positive effect on survival rate but a negative effect on dbh and total height. This result suggested that the amount of surrounding trees improved the survival of planted S. curtisii in the seedling stage and then inhibited growth of planted trees during the seedling and subsequent tree stages. We concluded that 30 m × 30 m plots with few surrounding trees on a gentle slope were effective for enhancing the growth of planted S. curtisii.