Leaf photosynthetic traits of 14 tropical rain forest species in relation to leaf nitrogen concentration and shade tolerance (original) (raw)
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Functional Ecology, 2000
Light-saturated rate of photosynthesis (A max), nitrogen (N), chlorophyll (Chl) content and leaf mass per unit area (LMA) were measured in leaves of trees of different heights along a natural light gradient in a French Guiana rain forest. The following four species, arranged in order from most shade-tolerant to pioneer, were studied: Duguetia surinamensis, Vouacapoua americana, Dicorynia guianensis and Goupia glabra. Light availability of trees was estimated using hemispherical photography. 2. The pioneer species Goupia had the lowest LMA and leaf N on both an area and mass basis, whereas Duguetia had the highest values. In general, leaf variables of Vouacapoua and Dicorynia tended to be intermediates. Because A max /area was similar among species, Goupia showed both a much higher light-saturated photosynthetic nitrogen-use efficiency (PNUE max) and A max /mass. Leaves of Vouacapoua demonstrated the greatest plasticity in A max /area, particularly in small saplings. 3. A distinction could be made between the effect of tree height and light availability on the structural, i.e. LMA, and photosynthetic leaf characteristics of all four species. The direction and magnitude of the variation in variables were similar among species. 4. LMA was the key variable that mainly determined variation in the other leaf variables along tree height and light availability gradients, with the exception of changes in chlorophyll concentration. A max /area, N/area, LMA and stomatal conductance to water vapour (g s) increased, whereas Chl/mass decreased, with both increasing tree height and canopy openness. A max /mass, PNUE max and A max /Chl increased with increasing openness only. N/mass and Chl/area were independent of tree height and openness, except for small saplings of Goupia which had a much lower Chl/area.
Tree Physiology, 2004
Photosynthetic rate, nitrogen concentration and morphological properties of canopy leaves were studied in 18 trees, comprising five dipterocarp species, in a tropical rain forest in Sarawak, Malaysia. Photosynthetic rate at light saturation (P max ) differed significantly across species, varying from 7 to 18 µmol m -2 s -1 . Leaf nitrogen concentration and morphological properties, such as leaf blade and palisade layer thickness, leaf mass per area (LMA) and surface area of mesophyll cells per unit leaf area (A mes /A), also varied significantly across species. Among the relationships with leaf characteristics, P max had the strongest correlation with leaf mesophyll parameters, such as palisade cell layer thickness (r 2 = 0.76, P < 0.001) and A mes /A (r 2 = 0.73, P < 0.001). Leaf nitrogen concentration and P max per unit area also had a significant but weaker correlation (r 2 = 0.46, P < 0.01), whereas P max had no correlation, or only weakly significant correlations, with leaf blade thickness and LMA. Shorea beccariana Burck, which had the highest P max of the species studied, also had the thickest palisade layer, with up to five or more layers. We conclude that interspecific variation in photosynthetic capacity in tropical rain forest canopies is influenced more by leaf mesophyll structure than by leaf thickness, LMA or leaf nitrogen concentration.
Functional Ecology, 1998
1. Parameters of the photosynthesis vs CO 2 response curve, nitrogen and chlorophyll contents were studied in Populus tremula, Tilia cordata and Corylus avellana leaves along a natural light gradient in the canopy. 2. In all species, leaf nitrogen content per unit area (N s ) declined with decreasing fractional transmission of photon flux density (K sum ), measured by a hemispheric photographic technique. However, the shape of the relationship between N s and K sum depended on species. N s was almost linearly related to K sum in the most light-demanding species P. tremula but this relationship was curved in two other species. Populus tremula possessed the largest values of N s at given K sum , while C. avellana, the most shade-tolerant species, had the lowest values of N s . 3. Both the initial slope, characterizing the maximum carboxylation efficiency, and the plateau value, providing an estimate of the photosynthetic electron transport capacity, of the photosynthesis vs CO 2 response curves, were linearly related to N s and only minor differences were observed among the studied species. Leaf chlorophyll content per area was also related to N s but the ratio of Chl/N increased substantially at low K sum in the lower canopy. It was concluded that the partitioning of nitrogen between light harvesting, electron transport and carboxylation components of the photosynthetic apparatus may change with depth in the canopy as a result of a relative increase in the light-harvesting complexes in relation to the rest of the photosynthetic apparatus. 4. The interspecific differences in species' photosynthetic potentials are mainly associated with different nitrogen distribution patterns along the canopy and in minor part with differences in nitrogen partitioning among photosynthetic machinery.
Maximum assimilation rate under saturating light level, leaf nitrogen and chlorophyll content and specific leaf mass were measured in forest plants grown under a range of canopy openness. Seedlings from three tree species cooccurring in damar agroforest (Sumatra) were examined: Shorea javanica, Lansium domesticum and Cinnamomum porrectum. A shrub species, Piper hispidum, growing in a different location was also investigated. All species showed pronounced differences in maximum photosynthetic potential when grown under different canopy openness. All tree seedlings showed an increase in maximum assimilation rate (A max ) with canopy openness (CO) until a certain threshold was reached. This saturation threshold varied between species. A steady increase in the maximum assimilation rate over the entire range of canopy openness explored was found only for Piper. Correlation between leaf nitrogen content and A max was usually highest when expressed on a per unit area basis. However the overall correlation was poor whether expressed per unit mass or per unit area when all species were pooled together questioning the universality of the relationship between both quantities. Potential photosynthetic nitrogen use efficiency, defined as the amount of CO 2 uptake per unit leaf nitrogen under saturating light level, was highest in Cinnamomum, supposedly the most light-demanding species, and lowest in Lansium, the understorey specialist.
Leaf traits show different relationships with shade tolerance in moist versus dry tropical forests
New Phytologist, 2009
Shade tolerance is the central paradigm for understanding forest succession and dynamics, but there is considerable debate as to what the salient features of shade tolerance are, whether adult leaves show similar shade adaptations to seedling leaves, and whether the same leaf adaptations are found in forests under different climatic control. • Here, adult leaf and metamer traits were measured for 39 tree species from a tropical moist semi-evergreen forest (1580 mm rain yr −1 ) and 41 species from a dry deciduous forest (1160 mm yr −1 ) in Bolivia. Twenty-six functional traits were measured and related to species regeneration light requirements. • Adult leaf traits were clearly associated with shade tolerance. Different, rather than stronger, shade adaptations were found for moist compared with dry forest species. Shade adaptations exclusively found in the evergreen moist forest were related to tough and persistent leaves, and shade adaptations in the dry deciduous forest were related to high light interception and water use.
Oecologia, 2015
was related to differences in within-leaf nitrogen allocation, with a tradeoff between investments into compounds related to photosynthetic capacity (higher in pioneer species) versus light-harvesting compounds (higher in climax species). Photosynthetic capacity was significantly lower at the warmer site at 1,700 m altitude. We conclude that (1) within-leaf nutrient allocation is more important than leaf nutrient content per se in controlling interspecific variation in photosynthetic capacity among tree species in tropical Rwanda, and that (2) tropical montane rainforest species exhibit decreased photosynthetic capacity when grown in a warmer environment.
Photosynthetica, 2004
We investigated the effect of growth irradiance (I) on photon-saturated photosynthetic rate (P max), dark respiration rate (R D), carboxylation efficiency (CE), and leaf mass per unit area (LMA) in seedlings of the following four tropical tree species with contrasting shade-tolerance. Anthocephalus chinensis (Rubiaceae) and Linociera insignis (Oleaceae) are light-demanding, Barringtonia macrostachya (Lecythidaceae) and Calophyllum polyanthum (Clusiaceae) are shade-tolerant. Their seedlings were pot-planted under shading nets with 8, 25, and 50 % daylight for five months. With increase of I, all species displayed the trends of increases of LMA, photosynthetic saturation irradiance, and chlorophyll-based P max , and decreases of chlorophyll (Chl) content on both area and mass bases, and mass-based P max , R D , and CE. The area-based P max and CE increased with I for the light-demanders only. Three of the four species significantly increased Chl-based CE with I. This indicated the increase of nitrogen (N) allocation to carboxylation enzyme relative to Chl with I. Compared to the two shade-tolerants, under the same I, the two light-demanders had greater area-and Chl-based P max , photosynthetic saturation irradiance, lower Chl content per unit area, and greater plasticity in LMA and area-or Chl-based P max. Our results support the hypothesis that light-demanding species is more plastic in leaf morphology and physiology than shade-tolerant species, and acclimation to I of tropical seedlings is more associated with leaf morphological adjustment relative to physiology. Leaf nitrogen partitioning between photosynthetic enzymes and Chl also play a role in the acclimation to I.
2009
optimal allocation of foliar nitrogen (ONA) predicts that both nitrogen concentration and photosynthetic capacity will scale linearly with gradients of insolation within plant canopies. ONA is expected to allow plants to efficiently use both light and nitrogen. However, empirical data generally do not exhibit perfect ONA, and light-use optimization per se is little explored. The aim was to examine to what degree partitioning of nitrogen or light is optimized in the crowns of three tropical canopy tree species. † Methods Instantaneous photosynthetic photon flux density (PPFD) incident on the adaxial surface of individual leaves was measured along vertical PPFD gradients in tree canopies at a frequency of 0 . 5 Hz over 9 -17 d, and summed to obtain the average daily integral of PPFD for each leaf to characterize its insolation regime. Also measured were leaf N per area (N area ), leaf mass per area (LMA), the cosine of leaf inclination and the parameters of the photosynthetic light response curve [ photosynthetic capacity (A max ), dark respiration (R d ), apparent quantum yield (f ) and curvature (u)]. The instantaneous PPFD measurements and light response curves were used to estimate leaf daily photosynthesis (A daily ) for each leaf. † Key Results Leaf N area and A max changed as a hyperbolic asymptotic function of the PPFD regime, not the linear relationship predicted by ONA. Despite this suboptimal nitrogen partitioning among leaves, A daily did increase linearly with PPFD regime through co-ordinated adjustments in both leaf angle and physiology along canopy gradients in insolation, exhibiting a strong convergence among the three species. † Conclusions The results suggest that canopy tree leaves in this tropical forest optimize photosynthetic use of PPFD rather than N per se. Tropical tree canopies then can be considered simple 'big-leaves' in which all constituent 'small leaves' use PPFD with the same photosynthetic efficiency.
Ecosystems, 2012
In tropical mountains, trees are the dominant life form from sea level to above 4,000-m altitude under highly variable thermal conditions (range of mean annual temperatures: <8 to >28°C). How light-saturated net photosynthesis of tropical trees adapts to variation in temperature, atmospheric CO 2 concentration, and further environmental factors, that change along elevation gradients, is not precisely known. With gas exchange measurements in mature trees, we determined light-saturated net photosynthesis at ambient temperature (T) and [CO 2 ] (A sat) of 40 tree species from 21 families in tropical mountain forests at 1000-, 2000-, and 3000-m elevation in southern Ecuador. We tested the hypothesis that stand-level averages of A sat and leaf dark respiration (R D) per leaf area remain constant with elevation. Standlevel means of A sat were 8.8, 11.3, and 7.2 lmol CO 2 m-2 s-1 ; those of R D 0.8, 0.6, and 0.7 lmol CO 2 m-2 s-1 at 1000-, 2000-, and 3000-m elevation, respectively, with no significant altitudinal trend. We obtained coefficients of among-species variation in A sat and R D of 20-53% (n = 10-16 tree species per stand). Examining our data in the context of a pan-tropical A sat data base for mature tropical trees (c. 170 species from 18 sites at variable elevation) revealed that area-based A sat decreases in tropical mountains by, on average, 1.3 lmol CO 2 m-2 s-1 per km altitude increase (or by 0.2 lmol CO 2 m-2 s-1 per K temperature decrease). The A sat decrease occurred despite an increase in leaf mass per area with altitude. Local geological and soil fertility conditions and related foliar N and P concentrations considerably influenced the altitudinal A sat patterns. We conclude that elevation is an important influencing factor of the photosynthetic activity of tropical trees. Lowered A sat together with a reduced stand leaf area decrease canopy C gain with elevation in tropical mountains.
Oecologia, 1994
Among 13 tropical tree species on Barro Colorado Island, species with high seedling mortality rates during the first year in shade had higher reltive growth rates (RGR) from germination to 2 months in both sun (23% full sun) and shade [2%, with and without lowered red: far red (R:FR) ratio] than shade tolerant species. Species with higher RGR in sun also had higher RGR in shade. These interspecific trends could be explained by differences in morphological traits and allocation paterns among species. Within each light regime, seedlings of shade-intolerant species had lower root: shoot ratios, higher leaf mass per unit area, and higher leaf area ratios (LAR) than shade tolerant species. In contrast, leaf gas exchange characteristics, or acclimation potential in these traits, had no relationship with seedling mortality rates in shade. In both shade tolerant and intolerant species, light saturated photosynthesis rates, dark respiration, and light compensation points were higher for sungrown seedlings than for shade-grown seedlings. Differences in R:FR ratio in shade did not affect gas exchange, allocation patterns, or growth rates of any species. Survival of young tree seedlings in shade did not depend on higher net photosynthesis or biomass accumulation rates in shade. Rather, species with higher RGR died faster in shade than species with lower RGR. This trend could be explained if survival depends on morphological characteristics likely to enhance defense against herbivores and pathogens, such as dense and tough leaves, a well-established root system, and high wood density. High construction costs for these traits, and low LAR as a consequence of these traits, should result in lower rates of whole-plant carbon gain and RGR for shade tolerant species than shade-intolerant species in shade as well as in sun.