Tree Seedling Growth and Survival in a Malaysian Rain Forest

Abstract

Growth and survival of tree seedlings were observed in lowland, evergreen, tropical rain forest in Pantai Aceh Forest Reserve, Penang, Peninsular Malaysia. Four natural gaps and two closed-canopy sites were used. In each site twenty 1 m2 plots were laid out at random and all the seedlings in them were identified, tagged, mapped, and measured for height and basal stem diameter, and the number of leaves were counted. After six months four of the sites were revisited, and after 16 months they were all revisited. Hemispherical canopy photographs were taken to calculate diffuse and direct site factors. At the start of the observations 1287 seedlings of 116 species were tagged. Over 16 months 251 (19.5%) seedlings died. Mortality was inversely correlated with seedling height. Potential direct radiation had no affect on seedling mortality. For the five common species the mortalities were: Shorea multiflora 6.2 percent, Hopea pedicellata 6.8 percent, Shorea curtisii 13.4 percent, Hopea beccariana 14.1 percent and Gluta curtisii 22.7 percent. The mortality of recruits from seed was: Shorea multiflora 19.0 percent, Shorea curtisii 29.1 percent and Gluta curtisii 29.5 percent. The seedlings grew very little over the 16 months. Height growth was greater in gap sites. There was a significant relationship between direct site factor and plot maximum height growth (r, = 0.399, P < 0.01) but its predictive value was poor (r2 = 0. 188). Gluta curtisii was the only species to show a significant relationship between direct site factor and height growth. Shorea multiflora and Gluta curtisii showed a significantly greater rate of height growth in the plots with above-median direct site factor compared to plots with below-median values. Shorea multiflora is a