Significance of architecture and allometry in saplings

Species differences in branching architecture and allometry were analysed for co-occurring forest floor saplings of 10 species of shade-tolerant evergreen broad-leaved tree, representative of primary warm-temperate rain forests in southern Japan, from the viewpoints of assimilative efficiency and significance for regeneration. Considerable diversity was found in the architecture of branching and in the leaf size of saplings. The differences in branching and leaf size were related to differences in allometric relationships between various properties of the saplings. It was hypothesized that this architectural and allometric diversity is related to the alternative of 'choosing' either the pattern of assimilate allocation, which is adaptive in competition when there is an early improvement in light conditions, or the allocation pattern which is favourable for surviving long periods under persistently dark conditions. Measurements of sapling growth in closed stands and in gaps supported the hypothesis.