Responses of three dipterocarp species to light regime

Abstract

Adaptability to light conditions was examined for seedlings of three species of Dipterocarpaceae, Shorea leprosula, S. ovalis and Dryobalanops lanceolata, possessing different ecological and silvicultural properties. S. leprosula and S. ovalis showed significant morphological adaptations to weak light conditions by changing leaf weight ratio, root weight ratio and leaf areal weight, as compared with D. lanceolata which is the most shade tolerant among the three species. When the shade-adapted leaves of each species were released from shading, they showed depression in photosynthetic activity, though the extent of depression differed with species. Only S. leprosula showed a recovery in photosynthetic rate 18 days after the release from shading. This result indicates that S. leprosula was more adaptable to increase in light intensity than the other two species. S. leprosula could be regarded as one of the adaptable species for reforestation in degraded open land.