Leaf size and leaf display of thirty-eight tropical tree species

Abstract

Trees forage for light through optimal leaf display. EVective leaf display is determined by metamer traits (i.e., the internode, petiole, and corresponding leaf), and thus these traits strongly co-determine carbon gain and as a result competitive advantage in a light-limited environment. We examined 11 metamer traits of sun and shade trees of 38 coexisting moist forest tree species and determined the relative strengths of intra-and interspeciWc variation. Species-speciWc metamer traits were related to two variables that represent important life history variation; the regeneration light requirements and average leaf size of the species. Metamer traits varied strongly across species and, in contrast to our expectation, showed only modest changes in response to light. Intra-and interspeciWc responses to light were only congruent for a third of the traits evaluated. Four traits, amongst which leaf size, speciWc leaf area (SLA), and leaf area ratio at the metamer level (LAR) showed even opposite intra-and interspeciWc responses to light. Strikingly, these are classic traits that are thought to be of paramount importance for plant performance but that have completely diVerent consequences within and across species. Sun trees of a given species had small leaves to reduce the heat load, but light-demanding species had large leaves compared to shade-tolerants, probably to outcompete their neighbors. Shade trees of a given species had a high SLA and LAR to capture more light in a light-limited environment, whereas shade-tolerant species have wellprotected leaves with a low SLA compared to lightdemanding species, probably to deter herbivores and enhance leaf lifespan. There was a leaf-size-mediated tradeoV between biomechanical and hydraulic safety, and the eYciency with which species can space their leaves and forage for light. Unexpectedly, metamer traits were more closely linked to leaf size than to regeneration light requirements, probably because leaf-size-related biomechanical and vascular constraints limit the trait combinations that are physically possible. This suggests that the leaf size spectrum overrules more subtle variation caused by the leaf economics spectrum, and that leaf size represents a more important strategy axis than previously thought.

Changing gears during succession: shifting functional strategies in young tropical secondary forests

“…To account for light-related variation, we recorded the crown exposure (1-5, ranging from no direct light to full direct light) of each sampled tree as a proxy for canopy openness (Poorter and Rozendaal 2008). From each tree, two branches located at similar crown positions were selected, placed in sealed plastic bags, and stored in a cooler.…”

Elevational trends in leaf size of Campylotropis polyantha in the arid Minjiang River valley, SW China

“…Leaf size and other functional traits are key determinants of plant performance in ecosystems (Blonder et al, 2011;Sack et al, 2012;Wright et al, 2004) and vary across complex environmental gradients such as elevation, topography and variations in factors related to climate (Buot and Okitsu, 1999;Klich, 2000;Körner, 2007;Poorter and Rozendaal, 2008;Thomas, 2011). Identifying how leaf traits change along these various gradients is an indispensable first step toward understanding the functional adaptations of plants to the environment (Castro-Díez et al, 2000;Dörken and Stützel, 2012).…”

Comparison of leaf anatomy on some Nepenthes spp. (Nepenthaceae) from highland and lowland habitat in Indonesia

“…A number of studies have suggested that leaf thickness increases with altitude, while frequency of leaf and size of leaf decreases [21,22,23]. Fibrous and thin leaves are more capable of rolling because of intensive sclerification [24] and it protecting their stomata from directs exposure to external environments [25].…”