SPATIAL PATTERN OF ADULT TREES AND SEEDLING SURVIVORSHIP IN <em>PENTASPADON</em> <em>MOTLEYI</em> IN A LOWLAND RAIN FOREST IN PENINSULAR MALAYSIA

Abstract

The spatial pattern of seedling survival was studied in a lowland rain forest in Peninsular Malaysia. The studies included 1) the distribution of adult trees and saplings (> 1 cm in dbh) of Pentaspadon motleyi locally known as pelong, based on data obtained in 1987 in a 50-ha plot where all trees > 1 cm dbh are mapped; 2) the survivorship of ca. 1-year-old seedlings in relation to distance from the nearest adult of pelong, seedling density and presence of light-gaps in a 1-ha plot for 78 weeks from August 1991. A total of 738 adult trees and saplings were found in the 50-ha plot. There were no saplings (1-2.5 cm dbh) within 6 m of conspecific adult trees more than 40 cm in dbh, but they did occur under non-conspecific adult trees. During the census, ca. 45% seedlings died. The mortality rate of seedlings close to the conspecific adult (0 - 2 m) was significantly greater than that away from it (> 2m). Transplanted seedlings growing in 4% full sunlight within a light-gap and in the nursery showed much higher survival and growth rates than those growing in 2-2.5% full sunlight under the canopy. The spatial distribution patterns of saplings in the 50-ha plot and seedling survivorship within the 1-ha plot indicate that seedling survivorship is affected to some extent by nearby conspecific adult trees. It also suggests that seedlings in the shade die before they grow to sapling size, unless they encounter light-gaps outside the crown area of the mother tree. The study suggests the importance of light-gaps which minimize the effects of distance- responsible-mortality agents on the seedlings.