Estimating near-infrared leaf reflectance from leaf structural characteristics

The relationship between near-infrared reflectance at 800 nm (NIRR) from leaves and characteristics of leaf structure known to affect photosynthesis was investigated in 48 species of alpine angiosperms. This wavelength was selected to discriminate the effects of leaf structure vs. chemical or water content on leaf reflectance. A quantitative model was first constructed correlating NIRR with leaf structural characteristics for six species, and then validated using all 48 species. Among the structural characteristics tested in the reflectance model were leaf trichome density, the presence or absence of both leaf bicoloration and a thick leaf cuticle (>1 μm), leaf thickness, the ratio of palisade mesophyll to spongy mesophyll thickness (PM/SM), the proportion of the mesophyll occupied by intercellular air spaces (%IAS), and the ratio of mesophyll cell surface area exposed to IAS (A(mes)) per unit leaf surface area (A), or A(mes)/A. Multiple regression analysis showed that measured NIRR was highly correlated with A(mes)/A, leaf bicoloration, and the presence of a thick leaf cuticle (r = 0.93). In contrast, correlations between NIRR and leaf trichome density, leaf thickness, the PM/SM ratio, or %IAS were relatively weak (r < 0.25). A model incorporating A(mes)/A, leaf bicoloration, and cuticle thickness predicted NIRR accurately for 48 species (r = 0.43; P < 0.01) and may be useful for linking remotely sensed data to plant structure and function.     

THE DEVELOPMENTAL RESPONSES OF PAPAYA LEAVES TO SIMULATED CANOPY SHADE

The developmental responses of plants to shade underneath foliage are influenced by reductions in irradiance and shifts in spectral quality (characterized by reductions in the quantum ratio of red to far-red wavelengths, R:FR). Previous research on the influence of shadelight on leaf development has neglected the reductions in R:FR characteristic of foliage shade, and these studies have almost certainly underestimated the extent and array of developmental responses to foliage shade. We have studied the effects of reduced irradiance and R:FR on the leaf development of papaya (Carica papaya L., Caricaceae). Using experimental shadehouses, replicates of plants grown in high light conditions (0.20 of sunlight and R:FR = 0.90) were compared to low light conditions (0.02 of sunlight) with either the spectral quality of sunlight (R:FR = 0.99) or of foliage shade (F:FR = 0.26). Although many characteristics, such as leaf thickness, specific leaf weight, stomatal density, palisade parenchyma cell shape, and the ratio of mesophyll air surface/leaf surface were affected by reductions in irradiance, reduced R:FR contributed to further changes. Some characters, such as reduced chlorophyll a/b ratios, reduced lobing, and greater internode length, were affected primarily by low R:FR. The reduced R:FR of foliage shade, presumably affecting phytochrome equilibrium, strongly influences the morphology and anatomy of papaya leaves.     

Bulb Development in Onion (Allium cepa L.) II. The Influence of Red: Far-red Spectral Ratio and of Photon Flux Density

Bulb development was followed in four onion cultivars growingin controlled environments under 17 h days in factorial combinationsof photon-flux densities (PFD) of 111 and 333 µmol m^–2s^–1 with red: far-red spectral ratios (R : FR) of 2.88and 1.41. A PFD of 111with R : FR of 0.86 was used in a secondexperiment. The lower the R : FR or the higher the PFD the higherthe mean bulbing ratio and the ratio of bulb plus sheath toleaf blade dry weight and the earlier the bulb swelling. LowerR : FR accelerated scale initiation as did the higher PFD underR : FR 2.88 but not under R : FR 1.41. In high PFD bulb swellingoccurred before scale initiation because many sheaths of bladedleaves thickened, but in low PFD and low R : FR bulb swellingand scale initiation were concurrent. In the low PFD a low R: FR increased soluble carbohydrate concentrations in sheathsand scales compared to high R : FR. In high PFD, soluble carbohydrateconcentrations did not vary with R : FR and were higher thanunder low PFD. Onion, Allium cepa L., bulb, photon flux density, red: far-red ratio, light spectral quality, soluble carbohydrate     

Effects of irradiance and spectral quality on seedling development of two Southeast Asian Hopea species

 Seedling developmental responses to understory shade combine the effects of reductions in irradiance and changes in spectral quality. We studied the seedling development of two Southeast Asian dipterocarp trees in response to differences in irradiance (photosynthetic photon flux density, PPFD) and spectral quality (red to far-red ratio, R:FR). The two species, Hopea helferei and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferei is more drought-tolerant and typically grows in more open habitats. Seedlings were grown in six different replicated shadehouse treatments varying in percentage of solar PPFD and R:FR. The two species differed in the influence of light variables on most seedling characters, particularly for final height, internode distance, branch/trunk internodes, stem length/mass, leaf area/stem length, petiole length, and growth/mol of photons received. Most of the characters in both taxa were primarily influenced by PPFD, but spectral quality also influenced some characters – more so for H. odorata. The latter species grew more rapidly, particularly in the low PPFD treatments, and its leaves were capable of higher photosynthesis rates. However, growth in H. helferei was not reduced in direct sunlight. The growth of this taxon may be constrained by adaptations, particularly in leaves, for drought tolerance. Received: 14 April 1996 / Accepted: 8 October 1996     

Petiole twisting in the crowns of<Emphasis Type="Italic"> Psychotria limonensis:</Emphasis> implications for light interception and daily carbon gain

We used Y-plant, a computer-based model of crown architecture, to examine the implications of leaf reorientation resulting from petiole bending in Psychotria limonensis (Rubiaceae) seedlings. During this reorientation process, bending of the petioles of lower leaves that are potentially self-shaded by the upper leaves rotates the lamina around the stem's orthotropic axis so that self-shading is reduced. Simulations of daily light capture and assimilation revealed a 66% increase in daily C gain due to reorientation of the leaves as compared to simulations where the leaves remained in their characteristic opposite decussate pattern set by the phyllotaxy. This was due to enhanced carbon (C) gain of the lower leaves because of the reduction of shading by upper developing leaves in the same vertical plane. The light signal for this movement was experimentally examined by placing leaf-shaped filters above already fully expanded leaves and following the resulting shade-avoiding movements. The filters were either neutral density shade cloth that reduced the photon flux density (PFD) but did not alter the red to far red ratio (R:FR) or a film that reduced the PFD equivalently but also reduced the R:FR. Leaf reorientation was much more rapid and complete under the low R:FR as compared to the high R:FR indicating involvement of a phytochrome photosensory system that detected the presence of a shading leaf. Plants in gaps were found to lack a reorientation response indicating that the reorientation is specific to the shaded understory environment.     

Light quality effects on corn chloroplast development

Corn was grown under greenhouse and controlled light quality conditions incluing full spectrum, red (R), and far-red (FR) sources. Young leaf samples were analyzed for pigments, pigment-proteins, membrane polypeptides, and ultrastructure. Chloroplast development in full spectrum white light was similar to that found in R but different from that found in FR plus low R. Compared to greenhouse and R, FR plus low R (670-760) repressed the formation of photosystem I reaction center protein (CP1 + CP1a) and enhanced those of photosystem II (CPa) in both bundle sheath and mesophyll cells. Photosystem II polypeptides were present in both cell types, with the 46 and 34 kilodalton proteins predominant in mesophyll cells. Bundle sheath cells contained relatively more of the 51 kilodalton and less of the 46 kilodalton proteins. However, they also contained measurable amounts of ribulose bisphosphate carboxylase which may interfere with estimates of the 51 kilodalton protein.     

Differential seed germination responses to the ratio of red to far-red light in temperate and tropical species

Variation in vegetation density creates a range of red to far-red ratios of irradiance (R:FR) potentially permitting fine-scale discrimination of light conditions for seed germination. However, remarkably few studies have explored whether R:FR responses of germination vary among species that differ in distribution and life-history traits. In this study, we explored the relationships between R:FR requirements and four species characteristics: seed mass, latitudinal distribution (tropical vs. temperate), seed dormancy (dormant vs. nondormant), and plant growth form (woody vs. nonwoody). We obtained data on germination response to R:FR of 62 species from published literature and added new data for ten species from aseasonal tropical forests in Borneo. First, we analyzed whether species characteristics influenced overall light dependency of germination using phylogenetic logistic regression. We found that seed mass had a strong negative effect on light dependency, but that the seed mass at which tropical taxa had a 50 % probability of light dependency was 40 times that of temperate taxa. For light-dependent species, we found that the threshold R:FR that stimulates 50 % of maximum germination (R:FR₅₀) was also related to seed mass and latitudinal distribution. In agreement with an earlier study, we found that for temperate taxa, the R:FR₅₀ was significantly negatively correlated with seed mass. In contrast, for 22 tropical taxa, we found a significant positive correlation. These opposing relationships suggest contrasting selection pressures on germination responses of tropical taxa (mostly trees) and temperate herbaceous plants, and which are likely related to differences in seed longevity, seed burial rates, and reproductive output.     

Leaf structure of Syzygium spp. (Myrtaceae) in relation to site affinity within a tropical rain forest

This study examined four species of Syzygium (S. firmum, S. makul, S. operculatum, S. rubicundum) Myrtaceae, a tree genus that dominates the canopy of rain forests of south‐west Sri Lanka. Syzygium spp. occupy differing habitats with relation to succession and forest topography. We examined differences in leaf morphology and physiology in response to amount of shade, an important environmental variable affecting Syzygium distribution within the forest. To study change in leaf structure and physiology, environmental shelters were constructed simulating forest shade that differed in quality, quantity and duration. Seedlings were exposed to: (i) 0% shade (full sun, FS), red : far red (R : FR) ratio 1.27; (ii) 65% shade (large opening, LO) with direct sunlight similar to the centre of a large canopy opening, R : FR ratio 1.27; (iii) 82% shade (small opening, SO) with direct sunlight similar to the centre of a small canopy opening, R : FR ratio 1.27; (iv) 58% uniform light shade (LS) with a quality similar to the outside edge of a large canopy opening, R : FR ratio 1.05; (v) 85% uniform medium shade (MS) with a quality similar to the inside forest edge of a large canopy opening, R : FR ratio 0.97; (vi) 99% uniform deep shade (DS) similar to that of the forest understorey, R : FR ratio 0.23. The shelters were constructed in a large open area at the field station of the Sinharaja World Heritage site, Sri Lanka. Seedlings of each species were grown for two years in their respective shade treatments before physiological, morphological and anatomical measurements were made on leaves. Variation in leaf structure and physiology between the species was associated with differences in shade‐tolerance and water‐use. All species increased in photosynthesis rates and dimensions in leaf structure (leaf blade and cuticle thickness, stomatal density, thickness of upper and lower epidermis, and thickness of palisade mesophyll) with decrease in shade. In contrast, stomatal conductivity was highest in the DS (99% shade) treatment. Leaves of Syzygium firmum were thickest and largest in area. S. firmum also had highest photosynthesis in the SO (82% shade) treatment. S. firmum was the most shade‐tolerant of all species: it grows well in low shade and its leaf structure suggests it to be the most conservative in water‐use of the Syzygium spp. In the forest S. firmum can persist in the forest shade as established seedlings, but grows best within canopy openings of late‐seral rain forest. Leaves of S. operculatum were thinnest but had highest stomatal densities of the four species. S. operculatum is considered shade‐intolerant, with a leaf structure suggesting it to be prone to desiccation, and by implication susceptible to drought. S. operculatum is found along streams within early seral rain forest habitat, often originating on stream banks after land clearance for cultivation. In the FS (0% shade) treatment, S. rubicundun had highest photosynthesis rates and greatest number of leaves but smallest leaf area of the Syzygium species. S. rubicundum is more shade‐intolerant but more efficient in water‐use than S. operculatum. S. rubicundum is a mid‐seral canopy tree of the midslope stands that are thought to have originated after catastrophic windthrows or swidden cultivation. The leaf physiology and structure of S. makul suggests it to be both moderately shade‐tolerant and conservative in water‐use. It is the most widely distributed Syzygium species across the topography of late‐seral rain forest. We suggest forest disturbance and hydrology are important environmental factors that influence distribution of Syzygium species across the topography. Results from this study contribute to a body of knowledge suggesting that canopy tree species of rain forests in south‐west Sri Lanka have discrete affinities to topography and differences in successional status, and that adaptations in leaf structure and physiology are indicative of such phenomena. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 141 , 365–377.     

Leaf anatomical characters and their value in understanding morphoclines in the Araceae

Leaf anatomy and petiole anatomy of the Araceae are discussed in terms of their potential use as character states in a phylogenetic analysis. The characters include leaf venation and structure, leaf epidermis, mesophyll ground tissue, vascular bundles, sclerenchyma, collenchyma, laticifers, secretory ducts, and raphide crystals. Characters that seem to have the greatest potential for use in phylogenetic analysis include those of ground tissue, vascular bundles, fibers, trichosclereids, collenchyma, and laticifers. Other, equally distinguishable, characters have states that are apparently autapomorphies, providing little phylogenetic signal. Therefore, although most leaf and petiole structural variation is useful diagnostically, some characters will probably be less valuable in phylogenetic analysis than originally hoped.     

Morphological and anatomical characteristics and taxonomical significance of achene micromorphology of Achillea phrygia and A. gypsicola (Asteraceae), endemic to Turkey

Micromorphological and anatomical characters of two Achillea L. species, A . phrygia Boiss. & Bal. and A. gypsicola Hub-Mor., which are endemic to Turkey, were investigated. It was observed that stem length, corymb width, number of capitula and median phyllary shape were diagnostic characters. In the anatomical studies, cross sections were taken from roots, stem and leaves. It was observed that roots of the investigated taxa had a secondary thickening. Endodermis and collenchyma layers were prominent in the stem of both taxa and they had a bifacial mesophyll while the layers of the mesophyll varied. Stomata were anomocytic in both species. We found that there was a significant difference in terms of width of epidermis cells and length of cortex cells in the root, epidermis width and length, collenchyma and parenchyma cells, endodermis length, diameter of trachea of stem, length of upper epidermis cells, width of lower epidermis cells, length of palisade parenchyma and spongy parenchyma cells, diameter of trachea and stomata length of leaf between the two taxa (p<0.05). Scanning electron microscopy (SEM) was used to describe the micromorphology of trichomes and achenes. In A. phrygia , long and eglandular trichomes were more dense on the stem and leaf epidermis. Achene micromorphological characteristics such as size, shape and achene coat were considered to be useful in separating the investigated species.     

An adaptive feature of some mangroves of Sundarbans, West Bengal

Mangrove taxa, apart from their morphological characters, have some unique leaf anatomical features which are very much related to their adaptation as the plants grow in unstable, variable and saline environments with regular tidal influence. Special stomatal structures with extended cuticles render the transpiration rate in many taxa. The presence of glandular and non-glandular hairs on the abaxial and/or adaxial leaf surfaces in some taxa are related to salt secretion of these plants. Comparatively large amounts of water storage tissues occur in the hypodermal or mesophyll tissue of the leaves, reflecting the adaptive nature of mangroves in their stressful habitat. The occurrence of terminal tracheids helps with capillary water storage within the leaf. The coriaceous nature of the leaves in some taxa is due to the presence of sclereids within the mesophyll region. It is noted thatHeritiera is unsuitable to the highly saline habitat of the Sundarbans forest region because of some anatomical peculiarities.     

Effects of growth-light quantity,growth-light quality and CO2 concentration on Rubisco deactivation during low PFD or darkness

The effects of CO₂ concentration and the effects of growth-light conditions on Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) deactivation were examined for Spinacea oleracea (spinach). Rubisco deactivation kinetics and the degree that Rubisco activation limited the rise in photosynthesis following an increase in photon flux density (PFD) were determined from gas-exchange time courses. There were no significant differences in the apparent relaxation time for Rubisco deactivation among leaves exposed to high or low CO₂ (50 or 1000 mol mol^-1) and low PFD (170 mol m^-2 s^-1) or darkness. However, when PFD was increased to 1700 mol m^-2 s^-1 following a period of low PFD or darkness, leaves exposed to low CO₂ × low PFD showed a lower contribution to the photosynthetic induction process by the activation of Rubisco than leaves exposed to the other treatments. For the growth-light experiments, spinach was grown under high PFD × high red:far-red ratio (R:FR), low PFD × high R:FR, or low PFD × low R:FR light environments. Leaves that matured under the low PFD × low R:FR treatment showed a lower percent change in photosynthesis due to Rubisco activation than leaves exposed to the other growth-light treatments. However, there were no significant differences among the growth-light treatments in the maximum contribution of Rubisco activation to the induction response or in the apparent relaxation time for Rubisco deactivation during shade events.     

Effects of light quality on leaf morphogenesis of a heterophyllous amphibious plant, Rotala hippuris

Background and Aims

For heterophyllous amphibious plants that experience fluctuating water levels, it is critical to control leaf development precisely in response to environmental cues that can serve as a quantitative index of water depth. Light quality can serve as such a cue because the ratio of red light relative to far-red light (R/FR) increases and blue-light intensity decreases with increasing water depth. Growth experiments were conducted to examine how R/FR and blue-light intensity alter leaf morphology of a heterophyllous amphibious plant, Rotala hippuris.

Methods

Using combinations of far red (730 nm), red (660 nm) and blue (470 nm) light-emitting diodes (LEDs), growth experiments were used to quantitatively evaluate the effects of the R/FR ratio and blue-light intensity on leaf morphology.

Key Results

Under the natural light regime in an outside growth garden, R. hippuris produced distinct leaves under submerged and aerial conditions. R/FR and blue-light intensity were found to markedly affect heterophyllous leaf formation. Higher and lower R/FR caused leaf characters more typical of submerged and aerial leaves, respectively, in both aerial and submerged conditions, in accordance with natural distribution of leaf types and light under water. High blue light caused a shift of trait values toward those of typical aerial leaves, and the response was most prominent under conditions of R/FR that were expected near the water surface.

Conclusions

R/FR and blue-light intensity provides quantitative cues for R. hippuris to detect water depth and determine the developmental fates of leaves, especially near the water surface. The utilization of these quantitative cues is expected to be important in habitats where plants experience water-level fluctuation.     

Leaf epidermal features of Salix species (Salicaceae) and their systematic significance

? Premise of the study: The classification of the genus Salix has historically been intrinsically difficult due to its propensity toward plasticity and high variation in diagnostic morphological characters. We investigated leaf epidermal characteristics, focusing on the stomatal apparatus because it may provide critical insights into the evolution and taxonomy of Salix and its closely related genera. ? Methods: Light microscopy was used to examine the leaf epidermal features in 32 taxa of Salix. ? Key results: Characters such as shape, size, and density of stomatal complexes were very useful in differentiating Salix species. Variation in features of stomatal apparatus in Salix is wider than previously known. Moreover, the type of stomatal complex proved to be very helpful in discriminating Chosenia as members of the genus Salix. ? Conclusions: The results of the present study support the placement of Chosenia within Salix and the combining of subgenera Chamaetia and Vetrix because of similarities in their unique stomatal apparatus.     

木槿的发育可塑性及种下分类研究

对紫花单瓣木槿、紫花重瓣木槿和牡丹木槿在叶和花部性状上的发育可塑性研究表明,三个种下类群,特别是紫花单瓣木槿和牡丹木槿的叶片性状具有很大的发育可塑性,但花部性状的发育可塑性则相对很小,暗示着花部性状较叶片性状具有更大的分类价值。通过种下类群间表型性状的比较,发现牡丹木槿在叶缘、叶柄长度、花色、花冠直径、花梗长度、果实长宽比等性状上都与其它两个类群存在显著差异,从而建议将牡丹木槿确立为亚种(H. syriacus Linn. subsp. paeoniflorus (Gagnep.)G. R. Shi)     

Control of ascorbic acid synthesis and accumulation and glutathione by the incident light red/far red ratio in Phaseolus vulgaris leaves

The effects of red/far red (R/FR) ratios on leaf ascorbate (AA) and glutathione (GSH) accumulation were examined in common bean (Phaseolus vulgaris L.). Growth under low R/FR ratios resulted in a “shade” phenotype and much lower leaf AA and GSH contents than high (R/FR) ratios. Photosynthesis rates were unaffected by changes in the R/FR ratio but leaf respiration rates, pyridine nucleotide pools and antioxidant enzyme activities were decreased under the low R/FR regime. The GSH pool changed slowly in response to altered R/FR ratios but leaf ascorbate acclimated over a single photoperiod. We conclude that light quality signals, particularly R/FR ratios, are important regulators of antioxidant synthesis and accumulation. These acclimatory changes are an early response to changing light environment.     

Variation in Ribulose 1,5 Bisphosphate Carboxylase Content in a Range of Winter Wheat Genotypes

Pyke, K A. and Leech, R. M. 1985. Variation in nbulose 1, 5bisphosphate carboxylase content in a range of winter wheatgenotypes. J. exp. Bot. 36: 1523–1529. Amounts of ribulose 1, 5 bisphosphate carboxylase (RuBPCase;E.C 4.1.1.39 [EC] ) were measured in the first leaves of 14 hexaploidwheat genotypes. The genotypes were representative of winterwheat grown in Britain during the past 150 years. The highest levels of RuBPCase per unit leaf area were foundin semi-dwarf genotypes which had more mesophyll cells per unitleaf area and smaller cells than tall genotypes. There was nosignificant correlation relating the year of introduction ofgenotypes to either the amount of RuBPCase per leaf or the amountper mesophyll cell Semi-dwarf genotypes tended to have smallerleaves and were less variable. Genotypic variation in the cellular content of RuBPCase is discussedin terms of genotypic differences in leaf development and thepotential for maximal RuBPCase accumulation. Key words: —Ribulose bisphosphate carboxylase, semi-dwarf wheat, cell size     

Responses of carbon acquisition traits to irradiance and light quality in Mercurialis annua (Euphorbiaceae): evidence for weak integration of plastic responses

It is often suggested that traits will be integrated, either because of pleiotropy or because natural selection may favor suites of integrated traits. Plant responses to different environments can provide evidence of such integration. We grew Mercurialis annua plants in high-density stands in high irradiance, in neutral shade, and in high red to far-red (R:FR) shade, resulting in environments of high irradiance, low R:FR; low irradiance, low R:FR; and low irradiance, high R:FR. We measured gas exchange, leaf morphology, stem elongation, and biomass traits and tested the prediction that traits within each functional group would show higher trait integration, as evidenced by high correlations among traits within environments, higher correlations of trait plasticity, and lower plasticity of trait correlations. Overall, we found evidence of only moderate integration for some groups of traits. Functionally related groups of traits, or pairs of traits, could be strongly integrated by one criterion but weakly integrated by another of the criteria. Stem elongation traits, though often observed to be strongly integrated in other taxa, showed little evidence of integration. Internode traits exhibited a novel pattern of responses to low R:FR, with increased elongation of the hypocotyl, decreased elongation of the first internode, and no change in the second internode. We propose that these responses to light are more likely to be the result of natural selection than the consequence of constraints imposed by pleiotropy.     

入侵物种飞机草和紫茎泽兰的核型研究

报道了菊科（Asteraceae）原泽兰属（Eupatorium）2种植物的核型,飞机草(Chromolaena odorata (L.) R. M. King &; H. Robinson）2n=60,核型公式为2n=60=32 m+28 sm,核型属于“2A”型,紫茎泽兰(Ageratina adenophora (Sprengel) R. King &; H. Robinson）2n=51,核型公式为2n=51=30 m+21 sm,核型属于“2B”型。飞机草的染色体数目变化较大,紫茎泽兰染色体数目较稳定。紫茎泽兰不能产生正常的花粉。飞机草有性生殖产生的种子发芽率低,紫茎泽兰无融合生殖产生的种子发芽率高,但2种植物入侵能力都很强,种子数量与2种植物的入侵性关系不大。     

Relative importance of photosynthetic traits and allocation patterns as correlates of seedling shade tolerance of 13 tropical trees

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.