PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Responses of crown development to canopy openings by saplings of eight tropical submontane forest tree species in Indonesia: comparison with cool temperate trees.

Takahashi, Koichi^*,1, Rustandi, Agus¹, ¹ Shinshu University, Matsumoto, Nagano, Japan

ABSTRACT- Responses of crown development to canopy openings in relation to trunk height growth were studied for saplings of eight tropical submontane forest tree species in Indonesia. The crown architecture differed between the eight species, i.e., they had sparsely to highly developed branching structure. Degree of branching was expressed as total length of trunk and branches. Highly branched species tended to have a large number of small leaves compared with sparsely branched species. In closed-canopy conditions, taller saplings of highly branched species had a larger sapling leaf area and a larger crown area than sparsely branched species. This suggests that sparsely branched species cannot develop their crowns as tree size increases. In contrast, the sapling leaf area increased more in taller saplings of sparsely branched species than in highly branched species without an increase in crown area in response to canopy openings. Although height growth rates of the eight species increased in response to canopy openings, interspecific variation in the degrees of increase was not correlated with branching structure. A general linear model showed that the degree of increase in height growth rate in response to canopy openings was more regulated by sapling leaf area for sparsely branched species compared with highly branched species. The results of this study were also compared with those for cool temperate deciduous broad-leaved trees in our previous study. This study concluded that (1) tropical submontane trees have responses similar to cool temperate trees to increase the height in canopy openings, i.e., taller saplings of sparsely branched species increase height growth rates by increasing the sapling leaf area, (2) cool temperate trees have a wider crown area and a smaller leaf area density to avoid self-shading within a crown compared with tropical submontane trees, and (3) plasticity of the crown area is greater by cool temperate trees than by tropical submontane trees probably because of the difference in leaf longevity.

Key words: Crown architecture, Height growth, Saplings, Plasticity