Changes in photosynthesis and leaf characteristics with tree height in five dipterocarp species in a tropical rain forest

Abstract

Variations in leaf photosynthetic, morphological and biochemical properties with increasing plant height from seedlings to emergent trees were investigated in five dipterocarp species in a Malaysian tropical rain forest. Canopy openness increased significantly with tree height. Photosynthetic properties, such as photosynthetic capacity at light saturation, light compensation point, maximum rate of carboxylation and maximum rate of photosynthetic electron transport, all increased significantly with tree height. Leaf morphological and biochemical traits, such as leaf mass per area, palisade layer thickness, nitrogen concentration per unit area, chlorophyll concentration per unit dry mass and chlorophyll to nitrogen ratio, also changed significantly with tree height. Leaf properties had simple and significant relationships with tree height, with few intra- and interspecies differences. Our results therefore suggest that the photosynthetic capacity of dipterocarp trees depends on tree height, and that the trees adapt to the light environment by adjusting their leaf morphological and biochemical properties. These results should aid in developing models that can accurately estimate carbon dioxide flux and biomass production in tropical rain forests.

Optimisation of photosynthetic carbon gain and within-canopy gradients of associated foliar traits for Amazon forest trees

“…8). This has been reported before for [N] A and M A in dipterocarp forests in Malaysia (Thomas and Bazzaz, 1999;Kenzo et al, 2006) with a tendency for taller trees to have a greater M A being an apparently general phenomenon (Poorter et al, 2009). This phenomenon will be dealt with in more detail in an accompanying paper utilising a much larger additional data set of individual trees for which only upper-canopy leaves had been sampled.…”

“…5) is a consequence of species-to-species variations, this being closely linked to other aspects of their physiological strategy including leaf lifespans (Wright et al, 2004) and hydraulic characteristics (Santiago et al, 2004;Meinzer et al, 2008). Such species dependent differences in key foliar physiological properties are also linked to practical morphological and anatomical constraints such as variations in leaf and palisade layer thickness and exposure of mesophyll surface area to the intercellular airspaces (Kenzo et al, 2006). That is not to say, of course, that both within-species variability and the modulation of key physiological traits by the environment does not occur.…”

“…8). As potassium plays a key role in the maintenance of leaf osmotic potentials as well as being critical for stomatal function (Leigh and Wyn Jones, 1984;Lebaudy et al, 2008) this may appear counter-intuitive as, other things being equal, leaves higher up in the canopy should have both higher gas exchange rates (Carswell et al, 2000;Kenzo et al, 2006;Niinemets, 2007) and more negative osmotic potentials (Myers et al, 1987;Oberbauer et al, 1997;Niinemets et al, 1999;Niinemets and Valladares, 2004). Nevertheless, soluble carbohydrate concentrations are usually high for sun exposed leaves (Lichtenthaler et al, 1991;Gleason and Ares, 2004) with these sugars making a critical contribution to the required more negative osmotic potentials for the leaves higher up the canopy stratum (Niinemets and Valladares, 2004), perhaps also replacing potassium in this role to some extent (Leigh and Wyn Jones, 1984).…”

Does ontogeny modulate irradiance-elicited plasticity of leaf traits in saplings of rain-forest tree species? A test with Dicorynia guianensis and Tachigali melinonii (Fabaceae, Caesalpinioideae)

“…In the present study we observed a significant increase of LMA with the sequence of ASDs in juvenile T. melinonii and to a lesser extent D. guianensis. Such an increase can be attributed to different factors: (i) Increased thickness, in particular of the palisade parenchyma as observed by Kenzo et al (2006) in some dipterocarp species. This was probably the case in T. melinonii (and to a lesser extent in D. guianensis) where leaf thickness increased with ASDs; (ii) Increased leaf density due to enhanced investment into structural support required to sustain larger lamina (Lusk and Warton, 2007 and references therein); increased density was indeed recorded in T. melinonii but again not in D. guianensis; (iii) Increased structural complexity due to the occurrence of branching may lead to restrictions of water supply to leaves due to hydraulic constrictions at branch bases; they may constrain leaf growth and result in smaller leaves (Niinemets, 2002;Thomas and Winner, 2002).…”

PHOTOSYNTHETIC PERFORMANCE AND LEAF WATER POTENTIAL OF GULUPA (Passiflora edulis Sims, PASSIFLORACEAE) IN THE REPRODUCTIVE PHASE IN THREE LOCATIONS IN THE COLOMBIAN ANDES

“…1987) for determining water use efficiency, which is reflected in the water status of the plant which can be measured through the water potential. The stomatal control and water status of plants change in accordance with the climatic conditions so they vary throughout the day (Pandey et al, 2003) and throughout the phenological cycle of plants (Thomas and Winner, 2002;Kenzo et al, 2006). The use of light by the photosynthetic apparatus is measured through chlorophyll fluorescence, allowing for the understanding of processes such as the photoinhibition caused by excess radiation that affects photosystems, causing chronic or dynamic damage (Aro et al, 1993).…”