A gradient of seedling growth from the centre of a tropical rain forest canopy gap

Seedlings of three species of dipterocarp were monitored on a 5 m wide transect from the centre of a large gap into the surrounding forest in a lowland rain forest in Malaysia for a period of 6 years from the time of gap creation. All three species grew taller the closer they were to the gap centre. Seedlings of Shorea johorensis were the tallest everywhere in the gap but almost all seedlings died beneath the forest canopy. Seedling mortality rather than a shift in the height growth hierarchy was responsible for partitioning of this transect between species. Along the forest edge, growth of seedlings of Hopea nervosa was temporarily enhanced by lateral penetration of light from the gap. The implications for natural forest regeneration dynamics are discussed.