Changes in shoot allometry with increasing tree height in a tropical canopy species, Elateriospermum tapos

Abstract

Allometry of shoot extension units (hereafter termed "current shoots") was analyzed in a Malaysian canopy species, Elateriospermum tapos Bl. (Euphorbiaceae). Changes in current shoot allometry with increasing tree height were related to growth and maintenance of tree crowns. Total biomass, biomass allocation ratio of non-photosynthetic to photosynthetic organs, and wood density of current shoots were unrelated to tree height. However, shoot structure changed with tree height. Compared with short trees, tall trees produced current shoots of the same mass but with thicker and shorter stems. Current shoots with thin and long stems enhanced height growth in short trees, whereas in tall trees, thick and short current shoots may reduce mechanical and hydraulic stresses. Furthermore, compared with short trees, tall trees produced current shoots with more leaves of lower dry mass, smaller area, and smaller specific leaf area (SLA). Short trees adapted to low light flux density by reducing mutual shading with large leaves having a large SLA. In contrast, tall trees reduced mutual shading within a shoot by producing more small leaves in distal than in proximal parts of the shoot stem. The production of a large number of small leaves promoted light penetration into the dense crowns of tall trees. All of these characteristics suggest that the change in current shoot structure with increasing tree height is adaptive in E. tapos, enabling short trees to maximize height growth and tall trees to maximize light capture.

Functional correlates of leaf demographic response to gap release in saplings of a shade-tolerant tree, Elateriospermum tapos

“…were present in the 50-ha permanent plot of the Pasoh Forest Reserve, primarily clustering on a hill (Manokaran et al 1992). Maximum height of E. tapos was about 40 m in this study site (Osada et al 2002a(Osada et al , 2002b. E. tapos has orthotropic monopodial shoots with 3/8 phyllotaxis.…”

Crown architecture and its role in species interactions in mixed boreal forests

“…Osada et al 2002;. The results indicated more vigorous growth and higher investment placed into long shoots compared to short ones in young trees compared to mature ones.…”

“…It is clear that the complex and dynamic crown architecture responds to the presence of neighbours in various manners and at several organisational levels (e.g. Aphalo and Ballaré 1995;Osada et al 2002;. The absolute height increment, relative growth rate of branches, leaf thickness and specific leaf area have been found to decrease and the ratio between stem height and diameter to increase with increasing competition intensity in young B. pendula grown in mixed stands under Pinus sylvestris (Messier and Puttonen 1995).…”

Plasticity in leaf-area density within the crown of Aucuba japonica growing under different light levels

“…The maximum value was one for EUs having only one node (or pair); this could be taken as the result of severe crowding. As a tree grows taller, current EU lengths become gradually shorter (Bonser and Aarssen 1994;Osada et al 2002) and leaves are produced along shorter internodes that increase mutual shading among leaves (Osada et al 2002). Shortening of EU length causes reduction in sites for leaf deployment (Aarssen 1995).…”