SPATIAL STUDIES OF SHOREA PARVIFOLIA SPP. PARVIFOLIA (DIPTEROCARPACEAE) IN A LOWLAND AND HILL DIPTEROCARP FOREST

Variation in tree species floristic composition and local-scale distribution in tropical forests is thought to be associated with habitat. This study compared the spatial distribution pattern and spatial genetic structure of Shorea parvifolia spp. parvifolia in a lowland and a hill dipterocarp forest and postulated how the spatial structure of a tropical tree species may be influenced by habitat heterogeneity. The significant spatial aggregation of S. parvifolia spp. parvifolia in both the lowland and hill dipterocarp forests indicated that seed dispersal was limited. The higher degree of habitat heterogeneity (e.g. topography, habitat type and resource availability) in hill dipterocarp forests compared with lowland dipterocarp forests, as established by previous research, may have contributed to the higher level of aggregation of S. parvifolia spp. parvifolia in the hill dipterocarp forest in the present study. The significant spatial genetic structure observed in the lowland dipterocarp forest may be due to restricted pollen and seed dispersal. In contrast, the absence of significant spatial genetic structure in the hill dipterocarp forest may indicate extensive pollen flow, and consequently, energetic and generalist pollinators (e.g. social bees Apis spp. and Trigona spp.) may be involved in the pollination of dipterocarps in the hill dipterocarp forests of Peninsular Malaysia.