THE RESPONSES TO SHADE OF SEEDLINGS OF VERY SMALL-SEEDED TREE AND SHRUB SPECIES FROM TROPICAL RAIN-FOREST IN SINGAPORE

1. Newly germinated seedlings of six tree and shrub species with very small seeds (31-460 mu g dry mass), one light-demanding and five shade -tolerant at the stage of establishment in the wild, were grown for 5 months in neutral shade houses with 0.5, 1, 3.5 and 7.5% daylight. 2. The ratio of yield in 7.5% to that in 1% was 8:1 for the Light-demandi ng Melastoma malabathricum but only 2:1 for the confamilial shade-tole rator Pternandra echinata. The Pternandra, Urophyllum hirsutum, Ficus chartacea, Ficus grossularioides and Pellacalyx saccardianus showed a graded series of responses to irradiance, generally consistent with th eir apparent demands for Eight in the wild. In contrast, survival of v ery deep shade was not clearly related to light demand in nature. 3. T he results support the conclusion drawn from observational studies tha t large seed size is not primarily adaptive in resisting shade but in resisting the associated risks of burial by litter, desiccation during dry spells, uprooting by birds and other kinds of damage by animals o r falling debris.