Juvenile height growth rate of seven major tree species in a tropical rain forest of West Sumatra

Abstract

Performances of juveniles are a key process for the existence of species in the community. Effect of topography, crowding effect and forest regeneration cycle, and conspecific plants in the context of Janzen-Connell hypothesis on height growth rate of seven major tree species were evaluated based on measurement of juveniles for nine-year period in a 1-ha plot of a tropical rain forest in West Sumatra, Indonesia. Height growth rate was significantly smaller in Calophyllum soulattri than other six species, and the latter species had approximately equivalent height growth rate. Growth rate was positively correlated with initial height in five species, but was negatively correlated in Calophyllum soulattri. Negative effect of conspecific juvenile density was detected by regression analysis only in Calophyllum soulattri. Topography was significant in two species (Hopea dryobalanoides and Mastixia trichotoma). Negative effects of total basal area including all species was found in one species (Swintonia schwenkii). Negative effects by conspecific plants was not dominant at least for height growth rate. Calophyllum soulattri was the only exception showing different behavior from the other species studied.