Ontogenetic changes in leaf phenology of a canopy species, Elateriospermum tapos (Euphorbiaceae), in a Malaysian rain forest

Abstract

Leaf phenology was studied in individuals of a canopy species, Elateriospermum tapos (Euphorbiaceae), at various ontogenetic stages, in a Malaysian rain forest. The timing of leaf emergence was not synchronized among sapling individuals, and was not correlated with any meteorological factors of the preceding month. The timing of leaf fall in saplings was positively correlated with net radiation, and maximum and minimum temperature, but negatively correlated with relative humidity the preceding month, although these correlations were weak. The leaf production rate was larger under higher light, but the leaf fall rate was not related to the light regime of the saplings. Thus, leaf production was enhanced by the light availability for each individual, while leaf fall may have been enhanced by drought stress. Non-synchronous leaf production appears to be important for sapling growth, allowing saplings to occupy better-lit space quickly. On the other hand, tall trees showed a clear synchronous leaf-fall pattern, with an annual cycle, and no meteorological factors were correlated with the timing of leaf fall. Mature trees of this species produced flowers simultaneously with new leaves, after shedding their leaves. This suggests that the need to synchronize flowering might be the primary determinant of leaf production phenology in mature individuals.

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.…”

“…E. tapos has orthotropic monopodial shoots with 3/8 phyllotaxis. Mature trees exchange leaves annually around February-March (Medway 1972;Whitmore 1972;Cranbrook and Edwards 1994;Osada et al 2002a). In contrast, saplings produce leaves non-synchronously, with more frequent leaf emergence in higher light environments (Osada et al 2002a).…”

“…Mature trees exchange leaves annually around February-March (Medway 1972;Whitmore 1972;Cranbrook and Edwards 1994;Osada et al 2002a). In contrast, saplings produce leaves non-synchronously, with more frequent leaf emergence in higher light environments (Osada et al 2002a). We selected six saplings of E. tapos, three in the shaded understory and three in treefall gaps, for this study of light environment, leaf demography, architecture, biomass allocation, and leaf nitrogen distribution.…”

Patterns of litter production in a secondary alluvial Atlantic Rain Forest in southern Brazil

“…However, Trewavas (2003Trewavas ( , 2004 believes that besides genotypic adaptation, plants can also sense very slight gradients of many environmental factors and in this way start their response mechanisms earlier or later in each specifi c year. The acquired experiences in the course of life of individuals in a community result in different performances (Baldwin 1896) and it can result in morphological and physiological changes affecting their phenology through ontogeny (Osada et al 2002). In the study area, January is usually the rainiest month according to historical data, but in the two studied years, February was the rainiest month.…”

Growth and reproduction of the understory palm Geonoma schottiana Mart. in the gallery forest in Central Brazil

“…First, the allocation of available resources among plant parts changes with individual size. In juveniles, sometimes resources are invested in the root system and in leaf production, while in adults they are allocated mainly to reproduction , Osada et al 2002. Reproductive palms can allocate about half of its annual dry weight increase to reproduction , so it is expected that leaf production rate be reduced when reproductive activities along the life cycle increase.…”