FOLIAR RESPONSES OF TREE SEEDLINGS TO DIFFERING LIGHT AND TOPOGRAPHIC POSITIONS IN A SINHARAJA FOREST

Abstract

Light is one of the most demanding and limiting factor in the lowland rain forests. Here we studied seedling foliar responses (anatomy and morphology) of nine tree species in genera Shorea, Dipterocarpus, Mesua and Syzygium to different light environments (gap and understory) across three topographies (valley, midslope and ridge). There were significant differences in anatomical and morphological trails among species due to differing light and topographic positions. All species had higher anatomical (thickness of leaf blade, upper and lower epidermis cell years, palisade mesophyll cell layers, cuticle layer thickness and stomatal density) and leaf morphological tails ( single leaf area, length, width, drip-tip length and petiole length) in canopy gaps than in the understory.  Among the species  Syzygium makul  had the thickest leaf blade in all gaps of each topography.  Shorea megistophylla had thickest upper epidermal in two lights and across topographies. Shorea disticha andShorea megistophylla  showed thickest palisade layer. S. makul   was greater in  stomatal density (number of stomata per unit area). Shorea megistophylla and D.s zeylanicus showed higher leaf area than other species. When compared the measured foliar responses S. megistophylla is most suitable for valley, while  D. zeylanicus, M. ferrea, S. makul and S. rubicundum for mid-slope sites. Mesua nagassarium, S. worthingtonii for ridge tops in both gap and the understory light environments. Finding indicate that the foliar traits are partially important in determination of species adaptation to particular light environment within the rain forest.