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Leaf Mass (leaf + mass)

Distribution by Scientific Domains

Life Sciences	90%
Earth and Environmental Science	9%

Distribution within Life Sciences

Ecology & Organismal Biology	31%
Plant Science	27%

Selected Abstracts

Can grazing response of herbaceous plants be predicted from simple vegetative traits?

JOURNAL OF APPLIED ECOLOGY, Issue 3 2001
Sandra Díaz
Summary 1,Range management is based on the response of plant species and communities to grazing intensity. The identification of easily measured plant functional traits that consistently predict grazing response in a wide spectrum of rangelands would be a major advance. 2,Sets of species from temperate subhumid upland grasslands of Argentina and Israel, grazed by cattle, were analysed to find out whether: (i) plants with contrasting grazing responses differed in terms of easily measured vegetative and life-history traits; (ii) their grazing response could be predicted from those traits; (iii) these patterns differed between the two countries. Leaf mass, area, specific area (SLA) and toughness were measured on 83 Argentine and 19 Israeli species. Species were classified by grazing response (grazing-susceptible or grazing-resistant) and plant height (< or > 40 cm) as well as by life history (annual or perennial) and taxonomy (monocotyledon or dicotyledon). 3,Similar plant traits were associated with a specific response to grazing in both Argentina and Israel. Grazing-resistant species were shorter in height, and had smaller, more tender, leaves, with higher SLA than grazing-susceptible species. Grazing resistance was associated with both avoidance traits (small height and leaf size) and tolerance traits (high SLA). Leaf toughness did not contribute to grazing resistance and may be related to selection for canopy dominance. 4,Plant height was the best single predictor of grazing response, followed by leaf mass. The best prediction of species grazing response was achieved by combining plant height, life history and leaf mass. SLA was a comparatively poor predictor of grazing response. 5,The ranges of plant traits, and some correlation patterns between them, differed markedly between species sets from Argentina and Israel. However, the significant relationships between plant traits and grazing response were maintained. 6,The results of this exploratory study suggest that prediction of grazing responses on the basis of easily measured plant traits is feasible and consistent between similar grazing systems in different regions. The results challenge the precept that intense cattle grazing necessarily favours species with tough, unpalatable, leaves. [source]

A test of the generality of leaf trait relationships on the Tibetan Plateau

NEW PHYTOLOGIST, Issue 4 2006
Jin-Sheng He
Summary ,,Leaf mass per area (LMA), nitrogen concentration (on mass and area bases, Nmass and Narea, respectively), photosynthetic capacity (Amass and Aarea) and photosynthetic nitrogen use efficiency (PNUE) are key foliar traits, but few data are available from cold, high-altitude environments. ,,Here, we systematically measured these leaf traits in 74 species at 49 research sites on the Tibetan Plateau to examine how these traits, measured near the extremes of plant tolerance, compare with global patterns. ,,Overall, Tibetan species had higher leaf nitrogen concentrations and photosynthetic capacities compared with a global dataset, but they had a slightly lower Amass at a given Nmass. These leaf trait relationships were consistent with those reported from the global dataset, with slopes of the standardized major axes Amass,LMA, Nmass,LMA and Amass,Nmass identical to those from the global dataset. Climate only weakly modulated leaf traits. ,,Our data indicate that covarying sets of leaf traits are consistent across environments and biogeographic regions. Our results demonstrate functional convergence of leaf trait relationships in an extreme environment. [source]

Differences in the structure, growth and survival of Parasenecio yatabei ramets with contrasting water relations on the slope of a stream bank

PLANT SPECIES BIOLOGY, Issue 2 2009
HAJIME TOMIMATSU
Abstract Parasenecio yatabei (Asteraceae), a summer-green perennial herb, is widely distributed on sloping mountain stream banks in cool-temperate zone forests of Japan. We investigated the growth pattern, leaf longevity and leaf water relations of vegetatively independent plants (ramets) growing in two contrasting soil water conditions, that is, upper and lower stream banks (U ramets and L ramets, respectively). The objective of the present study was to clarify the physiological and morphological responses of the ramets to soil water conditions. Dry matter allocation to subterranean parts was higher in U ramets than in L ramets. The U ramet leaves survived for approximately 2 months longer than L ramet leaves. The ratio of subterranean part to aerial part dry matter was greater in U ramets than L ramets. Leaf mass per leaf area (LMA) tended to be greater in U ramets than L ramets throughout the growing season. The leaf bulk modulus of elasticity at full hydration was significantly higher in U ramets. Thus, ramet growth patterns and morphological traits varied with changing soil water conditions. The greater longevity of U ramet leaves may play a role in compensating for the reduced annual net carbon gain caused by lower photosynthetic activity. U ramets growing in environments with less water availability achieved high water-use efficiency by a high passive water absorption capacity via a progressed root system and high productivity via longer leaf longevity with higher LMA and elasticity. Therefore, P. yatabei growing along mountain streams could have the ability to colonize the upper bank through higher survivorship based on these traits. [source]

Litter decomposition in a Cerrado savannah stream is retarded by leaf toughness, low dissolved nutrients and a low density of shredders

FRESHWATER BIOLOGY, Issue 8 2007
J. F. GONÇALVES JR
Summary 1. To assess whether the reported slow breakdown of litter in tropical Cerrado streams is due to local environmental conditions or to the intrinsic leaf characteristics of local plant species, we compared the breakdown of leaves from Protium brasiliense, a riparian species of Cerrado (Brazilian savannah), in a local and a temperate stream. The experiment was carried out at the time of the highest litter fall in the two locations. An additional summer experiment was conducted in the temperate stream to provide for similar temperature conditions. 2. The breakdown rates (k) of P. brasiliense leaves in the tropical Cerrado stream ranged from 0.0001 to 0.0008 day,1 and are among the slowest reported. They were significantly (F = 20.12, P < 0.05) lower than in the temperate stream (0.0046,0.0055). The maximum ergosterol content in decomposing leaves in the tropical Cerrado stream was 106 ,g g,1, (1.9% of leaf mass) measured by day 75, which was lower than in the temperate stream where maximum ergosterol content of 522 ,g g,1 (9.5% of leaf mass) was achieved by day 30. The ATP content, as an indicator of total microbial biomass, was up to four times higher in the tropical Cerrado than in the temperate stream (194.0 versus 49.4 nmoles g,1). 3. Unlike in the temperate stream, leaves in the tropical Cerrado were not colonised by shredder invertebrates. However, in none of the experiments did leaves exposed (coarse mesh bags) and unexposed (fine mesh bags) to invertebrates differ in breakdown rates (F = 1.15, P > 0.05), indicating that invertebrates were unable to feed on decomposing P. brasiliense leaves. 4. We conclude that the slow breakdown of P. brasiliense leaves in the tropical Cerrado stream was because of the low nutrient content in the water, particularly nitrate (0.05 mgN L,1), which slows down fungal activity and to the low density of invertebrates capable of using these hard leaves as an energy source. [source]

Allometry, growth and population regulation of the desert shrub Larrea tridentata

FUNCTIONAL ECOLOGY, Issue 2 2008
A. P. Allen
Summary 1Quantifying the effects of individual- and population-level processes on plant-community structure is of fundamental importance for understanding how biota contribute to the flux, storage and turnover of matter and energy in ecosystems. 2Here we synthesize plant-allometry theory with empirical data to evaluate the roles of individual metabolism and competition in structuring populations of the creosote Larrea tridentata, a dominant shrub in deserts of southwestern North America. 3At the individual level, creosote data support theoretical predictions with regard to the size dependence of total leaf mass, short-term growth rates of leaves and long-term growth rates of entire plants. Data also support the prediction that root,shoot biomass allocation is independent of plant size. 4At the population level, size,abundance relationships within creosote stands deviate strongly from patterns observed for steady-state closed-canopy forests due to episodic recruitment events. This finding highlights that carbon storage and turnover in water-limited ecosystems can be inherently less predictable than in mesic environments due to pronounced environmental forcing on demographic variables. 5Nevertheless, broad-scale comparative analyses across ecosystems indicate that the relationship of total abundance to average size for creosote populations adhere to the thinning rule observed and predicted by allometry theory. This finding indicates that primary production in water-limited ecosystems can be independent of standing biomass due to competition among plants for resources. 6Our synthesis of theory with empirical data quantifies the primary roles of individual-level metabolism and competition in controlling the dynamics of matter and energy in water-limited ecosystems. [source]

Leaf dark respiration as a function of canopy position in Nothofagus fusca trees grown at ambient and elevated CO2 partial pressures for 5 years

FUNCTIONAL ECOLOGY, Issue 4 2001
K. L. Griffin
Summary 1,Mass-based and area-based rates of respiration, leaf nitrogen content, leaf total protein content, non-structural carbohydrates and leaf mass per unit area (LMA) all decreased with depth in the canopy of Nothofagus fusca (Hook. F.) Oerst. (Red beech) trees grown for 5 years at ambient (36 Pa) or elevated (66 Pa) CO2 partial pressures. 2Elevated CO2 partial pressure had a strong effect on dark respiration, decreasing both mass-based and area-based rates at all canopy positions, but had little or no effect on leaf physical and biochemical properties. 3Leaf sugars, starch, protein, N and LMA were all correlated with respiration rate, and are therefore strong predictors of area-based dark respiration rates. The y axis intercept of regressions of respiration rate on mean leaf N, protein, starch and LMA was lower for plants grown at elevated compared to ambient CO2 partial pressures because of the differential effect of growth at elevated CO2 partial pressure on leaf gas-exchange, chemical and physical characteristics. 4,The lower respiration rates for leaves from trees grown at elevated CO2 partial pressure resulted in a significant increase in the ratio of light-saturated net photosynthesis to respiration, increasing the potential carbon-use efficiency of these leaves. [source]

Trade-offs in low-light CO2 exchange: a component of variation in shade tolerance among cold temperate tree seedlings

FUNCTIONAL ECOLOGY, Issue 2 2000
M. B. Walters
Abstract 1.,Does enhanced whole-plant CO2 exchange in moderately low to high light occur at the cost of greater CO2 loss rates at very-low light levels? We examined this question for first-year seedlings of intolerant Populus tremuloides and Betula papyrifera, intermediate Betula alleghaniensis, and tolerant Ostrya virginiana and Acer saccharum grown in moderately low (7·3% of open-sky) and low (2·8%) light. We predicted that, compared with shade-tolerant species, intolerant species would have characteristics leading to greater whole-plant CO2 exchange rates in moderately low to high light levels, and to higher CO2 loss rates at very-low light levels. 2.,Compared with shade-tolerant A. saccharum, less-tolerant species grown in both light treatments had greater mass-based photosynthetic rates, leaf, stem and root respiration rates, leaf mass:plant mass ratios and leaf area:leaf mass ratios, and similar whole-plant light compensation points and leaf-based quantum yields. 3.,Whole-plant CO2 exchange responses to light (0·3,600 µmol quanta m,2 s,1) indicated that intolerant species had more positive CO2 exchange rates at all but very-low light (< 15 µmol quanta m,2 s,1). In contrast, although tolerant A. saccharum had a net CO2 exchange disadvantage at light > 15 µmol quanta m,2 s,1, its lower respiration resulted in lower CO2 losses than other species at light < 15 µmol quanta m,2 s,1. 4.,Growth scaled closely with whole-plant CO2 exchange characteristics and especially with integrated whole-plant photosynthesis (i.e. leaf mass ratio × in situ leaf photosynthesis). In contrast, growth scaled poorly with leaf-level quantum yield, light compensation point, and light-saturated photosynthetic rate. 5.,Collectively these patterns indicated that: (a) no species was able to both minimize CO2 loss at very-low light (i.e. < 15 µmol quanta m,2 s,1) and maximize CO2 gain at higher light (i.e. > 15 µmol quanta m,2 s,1), because whole-plant respiration rates were positively associated with whole-plant photosynthesis at higher light; (b) shade-intolerant species possess traits that maximize whole-plant CO2 exchange (and thus growth) in moderately low to high light levels, but these traits may lead to long-term growth and survival disadvantages in very-low light (< 2·8%) owing, in part, to high respiration. In contrast, shade-tolerant species may minimize CO2 losses in very-low light at the expense of maximizing CO2 gain potential at higher light levels, but to the possible benefit of long-term survival in low light. [source]

The effect of tree height and light availability on photosynthetic leaf traits of four neotropical species differing in shade tolerance

FUNCTIONAL ECOLOGY, Issue 1 2000
T. Rijkers
Abstract 1.,Light-saturated rate of photosynthesis (Amax), 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 Amax/area was similar among species, Goupia showed both a much higher light-saturated photosynthetic nitrogen-use efficiency (PNUEmax) and Amax/mass. Leaves of Vouacapoua demonstrated the greatest plasticity in Amax/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. Amax/area, N/area, LMA and stomatal conductance to water vapour (gs) increased, whereas Chl/mass decreased, with both increasing tree height and canopy openness. Amax/mass, PNUEmax and Amax/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. [source]

Faster returns on ,leaf economics' and different biogeochemical niche in invasive compared with native plant species

GLOBAL CHANGE BIOLOGY, Issue 8 2010
JOSEP PENUELAS
Abstract Plant-invasive success is one of the most important current global changes in the biosphere. To understand which factors explain such success, we compared the foliar traits of 41 native and 47 alien-invasive plant species in Oahu Island (Hawaii), a location with a highly endemic flora that has evolved in isolation and is currently vulnerable to invasions by exotic plant species. Foliar traits, which in most cases presented significant phylogenetic signal, i.e. closely related species tended to resemble each other due to shared ancestry, separated invasive from native species. Invasive species had lower leaf mass per area and enhanced capacities in terms of productivity (photosynthetic capacity) and nutrient capture both of macro- (N, P, K) and microelements (Fe, Ni, Cu and Zn). All these differences remain highly significant after removing the effects of phylogenetic history. Alien-invasive species did not show higher efficiency at using limiting nutrient resources, but they got faster leaf economics returns and occupied a different biogeochemical niche, which helps to explain the success of invasive plants and suggests that potential increases in soil nutrient availability might favor further invasive plant success. [source]

Responses of plants in polar regions to UVB exposure: a meta-analysis

GLOBAL CHANGE BIOLOGY, Issue 11 2009
KEVIN K. NEWSHAM
Abstract We report a meta-analysis of data from 34 field studies into the effects of ultraviolet B (UVB) radiation on Arctic and Antarctic bryophytes and angiosperms. The studies measured plant responses to decreases in UVB radiation under screens, natural fluctuations in UVB irradiance or increases in UVB radiation applied from fluorescent UV lamps. Exposure to UVB radiation was found to increase the concentrations of UVB absorbing compounds in leaves or thalli by 7% and 25% (expressed on a mass or area basis, respectively). UVB exposure also reduced aboveground biomass and plant height by 15% and 10%, respectively, and increased DNA damage by 90%. No effects of UVB exposure were found on carotenoid or chlorophyll concentrations, net photosynthesis, Fv/Fm or ,PSII, belowground or total biomass, leaf mass, leaf area or specific leaf area (SLA). The methodology adopted influenced the concentration of UVB absorbing compounds, with screens and natural fluctuations promoting significant changes in the concentrations of these pigments, but lamps failing to elicit a response. Greater reductions in leaf area and SLA, and greater increases in concentrations of carotenoids, were found in experiments based in Antarctica than in those in the Arctic. Bryophytes typically responded in the same way as angiosperms to UVB exposure. Regression analyses indicated that the percentage difference in UVB dose between treatment and control plots was positively associated with concentrations of UVB absorbing compounds and carotenoids, and negatively so with aboveground biomass and leaf area. We conclude that, despite being dominated by bryophytes, the vegetation of polar regions responds to UVB exposure in a similar way to higher plant-dominated vegetation at lower latitudes. In broad terms, the exposure of plants in these regions to UVB radiation elicits the synthesis of UVB absorbing compounds, reduces aboveground biomass and height, and increases DNA damage. [source]

Responses of leaf nitrogen concentration and specific leaf area to atmospheric CO2 enrichment: a retrospective synthesis across 62 species

GLOBAL CHANGE BIOLOGY, Issue 7 2002
Xiwei Yin
Abstract Knowledge of leaf responses to elevated atmospheric [CO2] (CO2 concentration) is integral to understanding interactions between vegetation and global change. This work deals with responses of leaf mass-based nitrogen concentration (Nm) and specific leaf area (SLA). It assesses the statistical significance of factors perceived as influential on the responses, and quantifies how the responses vary with the significant factors identified, based on 170 data cases of 62 species compiled from the literature. Resultant equations capture about 41% of the variance in the data for percent responses of Nm and SLA, or about 95% of the variance for Nm and SLA at 57,320% normal [CO2]; these performance statistics also hold for leaf area-based N concentration and specific leaf weight. The equations generalize that: (i) both Nm and SLA decline as [CO2] increases; (ii) proportional decline of Nm is greater with deciduous woody species and with plants of normally low Nm, increases with pot size in growth chamber and greenhouse settings and with temperature and photosynthetic photon flux density (PPFD), and is mitigated by N fertilization; and (iii) proportional decline of SLA depends on pot size and PPFD similarly to Nm, increases with leaf life span and water vapour pressure deficit in enclosed experiments, and decreases with prolonged exposure to elevated [CO2] among broadleaf woody species in field conditions. The results highlight great uncertainty in the percent-response data and reveal the potential feasibility to estimate Nm and SLA at various magnitudes of elevated [CO2] from a few key plant and environmental factors of broad data bases. [source]

The influence of sward canopy structure on foraging decisions by grazing cattle.

GRASS & FORAGE SCIENCE, Issue 2 2003

Abstract Patch selection by grazing dairy cows in response to simultaneous variation in combinations of sward structural characteristics was examined in three experiments in which four mature dairy cows were offered a choice of patches (typically 0.9 m × 0.9 m) of perennial ryegrass (Lolium perenne) presented in a linear arrangement. Treatments involved combinations of variations in sward height, stubble height and/or depth of regrowth, prepared by preliminary cutting treatments. They were arranged in balanced sets of four to nine treatments, which were arranged in linear sequences of eighteen to twenty-seven patches. Within experiments, sequences were balanced across replicate sets of patches, which were grazed separately by individual cows. The number of bites removed and the residence time for each patch were highly correlated in all three experiments, and the results are reported using number of bites per patch as an estimator of foraging behaviour. In the first experiment, with vegetative swards, cows preferentially selected the tallest swards. When swards comprising reproductive stem were offered in Experiment 2, cows selectively grazed short-stubble swards rather than tall-stubble swards, although both offered a similar depth of regrowth. Cows did not exhibit preference for swards comprising the greatest quantity of leaf mass, indicating that the spatial distribution of plant components assumed greater importance. In the third experiment, the number of bites removed increased with increasing depth of regrowth, and was negatively correlated with sward height. The three patch-appraisal cues investigated were broadly ranked in order of importance as (i) depth of regrowth, (ii) sward maturity and (iii) sward height. There was no evidence, at least at a short temporal scale, that patch behaviour was influenced by conditions in adjacent patches, suggesting that the cows assessed grazing opportunities on a patch-by-patch basis. [source]

The effect of sward structure as influenced by ryegrass genotype on bite dimensions and short-term intake rate by dairy cows

GRASS & FORAGE SCIENCE, Issue 1 2003
P. D. Barrett
Abstract The effects of genotypic variation in ryegrasses on sward structure, bite dimensions and intake rate by dairy cows were investigated. Two experiments were conducted. In Experiment 1, swards were in a vegetative state whereas, in Experiment 2, they were partly reproductive and were taller with higher herbage mass but lower leaf proportion than in Experiment 1. Applicability of relationships between sward structure and bite characteristics, previously established from artificial or hand-constructed swards, to field conditions were tested. Additional short-term intake rates and/or sward structural characteristics were considered as indicators of potential intake for use in protocols for the evaluation of grass varieties. Four cultivars were studied: AberElan, Twins (diploid and tetraploid perennial ryegrasses respectively), Polly, a hybrid ryegrass (perennial × Italian ryegrass) and Multimo (Italian ryegrass), each established in 200-m2 plots in four replicated blocks. Herbage intake rate was determined by short-term liveweight change (taking account of insensible weight loss) using 16 dairy cows allocated to four balanced groups with each plot grazed by one group for a 1-h assessment period. One block was grazed per day, over a 4-d experimental period, with each group grazing each variety in a complete crossover design. Sward characteristics and bite rate were also measured in both experiments. Bite dimensions were subsequently estimated, with bite depth being determined as a function of extended tiller height (ETH) in both experiments. Within both experiments, bite mass and intake rate did not differ significantly between swards of different cultivars despite swards containing Multimo generally having a higher ETH and water-soluble carbohydrate concentration and lower green leaf mass, sward bulk density and neutral-detergent fibre concentration than the other swards. However, bite depth was significantly higher (P < 0·01) in swards containing Multimo swards than in the others and, in Experiment 1, bite depth, as a proportion of ETH, was higher in swards containing Multimo and lower in those containing Twins than in the other two cultivars, whereas there was no difference in Experiment 2. Taking both experiments together, the mean bite depth was 0·5 of ETH with sward bulk density accounting for almost half the variance in the relationship between bite depth and ETH. The bulk density of the bite (bite mass per unit bite volume), measured in Experiment 2, followed a similar pattern to sward bulk density, increasing in the order Multimo, Polly, AberElan and Twins. It is concluded that the relationships between sward characteristics and bite dimensions, derived from artificial swards, are applicable to field swards, although the range in natural ryegrass sward characteristics is usually not as wide as in experiments using artificial swards. Lack of precision in the measurement of short-term intake and in sward-based measurements is likely to preclude their use in the evaluation of grass varieties. [source]

The geographical range structure of the holly leaf-miner.

JOURNAL OF ANIMAL ECOLOGY, Issue 5 2004

Summary 1Spatial variation and covariation in host-plant quality, herbivore abundance and herbivore mortality were examined across the natural geographical range in Europe of holly Ilex aquifolium and the host-specific holly leaf-miner Phytomyza ilicis. 2Although measures of host-plant quality showed substantial between-site variation, no simple spatial pattern in any of the measures (only phosphorus content and leaf mass showed correlations with latitude, longitude or altitude) was detected, and few correlations with tree or local site characteristics. 3In contrast, measures of the abundance of the leaf-miner exhibited marked spatial patterns, resulting in a lack of simple covariance between leaf-miner abundance and host-plant quality. 4Different apparent mortalities of the leaf-miner exhibited varied spatial patterns in their intensity, but no evidence of range-wide density dependence, again resulting in few patterns of covariance between intensity of mortality and measures of host-plant quality. 5The population dynamics of the holly leaf-miner across its geographical range are complex. At any site, the mortality that a population experiences is the sum of largely independent yet spatially structured components, against a background of varying host-plant quality. Despite lacking any marked spatial structure, host-plant quality may have important local effects. These are difficult to detect regionally, and thus may principally contribute noise to regional patterns of levels of oviposition, abundance and mortality. [source]

Can grazing response of herbaceous plants be predicted from simple vegetative traits?

Effects of simulated browsing on growth and leaf chemical properties in Colophospermum mopane saplings

AFRICAN JOURNAL OF ECOLOGY, Issue 1 2010
Edward M. Kohi
Abstract Browsing intensity influences a plant's response to herbivory. Plants face a trade-off between investment in the production of secondary compounds and investment in growth. To elucidate this trade-off, we simulated four browsing intensities (0%, 50%, 75% and 100%) on mopane saplings, Colophospermum mopane (J. Kirk ex Benth.) J.Léonard, in a greenhouse experiment. This showed that, with increasing defoliation intensity, plants change their investment strategy. At intermediate levels of defoliation (50%), mopane saplings increased the synthesis of condensed tannins, so that tannin concentrations followed a hump-shaped relation with defoliation intensity, with significantly higher tannin concentration at intermediate defoliation levels. When defoliated heavily (75% and 100%), tannin concentrations dropped, and plants were carbon stressed as indicated by a reduced growth rate of the stem diameter, and leaf production and mean individual leaf mass were reduced. This suggests that, at intermediate defoliation intensity, the strategy of the plants is towards induced chemical defences. With increasing defoliation, the relative costs of the secondary metabolite synthesis become too high, and therefore, the plants change their growing strategy. Hence, browsers should be able to benefit from earlier browsing by either adopting a low or a relatively high browsing pressure. Résumé La réponse d'une plante à sa consommation dépend de l'intensité de ce phénomène. Les plantes sont confrontées à un compromis entre un investissement dans la production de composants secondaires et un investissement dans leur croissance. Pour élucider ce compromis, nous avons simulé quatre intensités de consommation (0%, 50%, 75% et 100%) sur des jeunes mopanes, Colophospermum mopane (J. Kirk ex Benth.) J.Leonard, lors d'expériences sous serre. Ceci a montré que, lorsque la défoliation s'intensifie, les plantes changent leur stratégie d'investissement. À des niveaux de défoliation intermédiaires (50%), les jeunes plants de mopanes augmentaient la synthèse de tanins condensés, de sorte que les concentrations en tanins suivaient une courbe en cloche (hump-shaped) selon l'intensité de la défoliation; elles étaient significativement plus élevées aux niveaux de défoliation intermédiaires. Lorsque les plantes sont fortement défoliées (75% et 100%), leurs concentrations en tanins chutent, et elles sont en stress carbone comme le montre le taux de croissance réduit du diamètre du tronc; la production de feuilles et la masse moyenne de feuilles par individu sont aussi réduites. Cela suggère que, quand l'intensité de défoliation est intermédiaire, la stratégie des plants va vers une défense chimique induite. Lorsque la défoliation augmente, le coût relatif de la synthèse du métabolite secondaire devient trop élevé et le plant change de stratégie de croissance. Donc, les herbivores qui les consomment devraient pouvoir bénéficier d'une consommation antérieure en adoptant une pression de consommation faible ou relativement élevée. [source]

Chemical and physical plant defence across multiple ontogenetic stages in a tropical rain forest understorey tree

JOURNAL OF ECOLOGY, Issue 4 2009
Bruce L. Webber
Summary 1Variation over plant ontogeny can play an important role in shaping trade-offs between investing resources in growth, reproduction and defence. Most previous ontogenetic studies on plant defence have compared two life stages, making it impossible to follow complete ontogenetic trajectories for plant defence traits. 2We used the highly defended rain forest understorey tree Ryparosa kurrangii to examine chemical (cyanogen concentrations; CNM) and physical (leaf mass per area; LMA) ontogenetic defence trajectories across multiple stages of development for the first time, using field and glasshouse plants. 3In glasshouse seedlings, total plant cyanide and CNM decreased between cotyledon-bearing and recently autonomous seedlings. In field populations, foliar CNM decreased in a nonlinear fashion and showed a trade-off with LMA through the ontogenetic progression from small seedlings to large mature trees. 4Cyanogenesis was ubiquitous in all individuals tested, with considerable quantitative plasticity in constitutive expression. Environmental influences on defence traits, as measured by foliar nitrogen and potential light availability in the field, had no detectable effect on CNM. Non-cyanide nitrogen (N , NCN)M was negatively correlated with CNM, and NCN was negatively correlated with plant height; therefore, at constant plant height there was no relationship between (N , NCN)M and CNM. LMA was positively correlated with increasing light availability. 5Our results suggest that light and nitrogen availability have no detectable effect on CNM in R. kurrangii and that most of the observed population-level CNM plasticity may be due to underlying genetic and ontogenetic influences. These findings are related to a theoretical model recently proposed for resistance trajectories during plant ontogeny, taking into account the life-history traits of rain forest understorey trees. 6Synthesis. The nonlinear ontogenetic trajectory of plant defence expression observed in this study suggests that ontogenetic defence changes may be strongly influenced by plant life-history traits, the defence(s) examined and the environmental niche the plant occupies. [source]

Biomass allocation and leaf life span in relation to light interception by tropical forest plants during the first years of secondary succession

JOURNAL OF ECOLOGY, Issue 6 2008
N. Galia Selaya
Summary 1We related above-ground biomass allocation to light interception by trees and lianas growing in three tropical rain forest stands that were 0.5, 2 and 3-year-old regeneration stages after slash and burn agriculture. 2Stem height and diameter, leaf angle, the vertical distribution of total above-ground biomass and leaf longevity were measured in individuals of three short-lived pioneers (SLP), four later successional species (LS) and three lianas (L). Daily light capture per individual (,d) was calculated with a canopy model. Mean daily light interception per unit leaf area (,area), leaf mass (,leaf mass) and above-ground mass (,mass) were used as measures of instantaneous efficiency of biomass use for light capture. 3With increasing stand age, vegetation height and leaf area index increased while light at the forest floor declined from 34 to 5%. The SLP, Trema micanthra and Ochroma pyramidale, dominated the canopy early in succession and became three times taller than the other species. SLP had lower leaf mass fractions and leaf area ratios than the other groups and this difference increased with stand age. 4Over time, the SLP intercepted increasingly more light per unit leaf mass than the other species. Lianas, which in the earliest stage were self-supporting and started climbing later on, gradually became taller at a given mass and diameter than the trees. Yet, they were not more efficient than trees in light interception. 5SLP had at least three-fold shorter leaf life spans than LS and lianas. Consequently, total light interception calculated over the mean life span of leaves (,leaf mass total = ,area × SLAdeath leaves× leaf longevity) was considerably lower for the SLP than for the other groups. 6Synthesis. We suggest that early dominance in secondary forest is associated with a high rate of leaf turnover which in turn causes inefficient long-term use of biomass for light capture, whereas persistence in the shade is associated with long leaf life spans. This analysis shows how inherent tradeoffs in crown and leaf traits drive long-term competition for light, and it presents a conceptual tool to explain why early dominants are not also the long-term dominants. [source]

Prey availability directly affects physiology, growth, nutrient allocation and scaling relationships among leaf traits in 10 carnivorous plant species

JOURNAL OF ECOLOGY, Issue 1 2008
Elizabeth J. Farnsworth
Summary 1Scaling relationships among photosynthetic rates, leaf mass per unit area (LMA), and foliar nitrogen (N) and phosphorus (P) content hold across a diverse spectrum of plant species. Carnivorous plants depart from this spectrum because they dedicate substantial leaf area to capturing prey, from which they derive N and P. We conducted a manipulative feeding experiment to test whether scaling relationships of carnivorous plant leaf traits become more similar to those of non-carnivorous taxa when nutrients are not limiting. 2We examined the effects of prey availability on mass-based maximum photosynthetic rate (Amass), chlorophyll fluorescence, foliar nutrient and chlorophyll content, and relative growth rate of 10 Sarracenia species. We hypothesized that increased prey intake would stimulate Amass, reduce stress-related chlorophyll fluorescence, increase photosynthetic nutrient-use efficiencies (PNUEN, PNUEP), and increase relative biomass allocation to photosynthetically efficient, non-carnivorous phyllodes. 3Two plants per species were assigned in a regression design to one of six weekly feedings of finely ground wasps: 0,0.25 g for small plant species; 0,0.5 g for intermediate-sized species; and 0,1.0 g for large species. The first two leaves emerging on each plant were fed. 4Increased prey availability increased photosystem efficiency (Fv/Fm ratio) in the first two leaves, and chlorophyll content and Amass in younger leaves as older leaves rapidly translocated nutrients to growing tissues. Higher prey inputs also led to lower N : P ratios and a shift from P- to N-limitation in younger leaves. PNUEP was significantly enhanced whilst PNUEN was not. Better-fed plants grew faster and produced a significantly higher proportion of phyllodes than controls. 5Feeding shifted scaling relationships of P relative to Amass, N and LMA from outside the third bivariate quartile to within the 50th bivariate percentile of the universal spectrum of leaf traits; other scaling relationships were unaffected. Carnivorous plants can rapidly reallocate P when nutrients are plentiful, but appear to be less flexible in terms of N allocation. 6Synthesis. Our results support the general hypothesis put forward by Shipley et al. (2006) that observed scaling relationships amongst leaf traits derive from trade-offs in allocation to structural tissues vs. liquid-phase (e.g. photosynthetic) processes. These trade-offs appear to be especially constraining for plants growing in extremely nutrient-poor habitats such as bogs and other wetlands. [source]

Convergence towards higher leaf mass per area in dry and nutrient-poor habitats has different consequences for leaf life span

JOURNAL OF ECOLOGY, Issue 3 2002
Ian J. Wright
Summary 1,Leaf life span (LL) and leaf mass per area (LMA) are fundamental traits in the carbon economy of plants, representing the investment required per unit leaf area (LMA) and the duration of the resulting benefit (LL). Species on dry and infertile soils converge towards higher LMA. It has been generally assumed that this allows species from low-resource habitats to achieve longer average leaf life spans, as LMA and LL are often correlated. 2,Leaf life span and LMA were measured for 75 perennial species from eastern Australia. Species were sampled from nutrient-rich and nutrient-poor sites within high and low rainfall regions. LL and LMA were positively correlated across species within each site. In addition, evolutionary divergences in LL and LMA were correlated within each site, indicating that cross-species relationships were not simply driven by differences between higher taxonomic groups. 3,Within a rainfall zone, LL,LMA combinations shifted as expected along common axes of variation such that species on poorer soils had higher LMA and longer LL, but significantly so only at high rainfall. 4,Low rainfall species were expected to have shorter LL at a given LMA or, equally, require higher LMA to achieve a given LL, i.e. shift to a parallel axis of variation, and this was observed on both nutrient-rich and nutrient-poor soils. On average, 30% higher LMA was seemingly required at dry sites to achieve a given LL. Thus, convergence towards higher LMA has different consequences for leaf life span in dry and nutrient-poor habitats. 5,The broad shifts in LL,LMA combinations between site types were also seen when comparing closely related species-pairs (phylogenetically independent contrasts) occurring on nutrient-rich and nutrient-poor soils (within each rainfall zone), and at high- and low-rainfall sites (at each soil nutrient level). [source]

Plant traits and functional types in response to reduced disturbance in a semi-natural grassland

JOURNAL OF VEGETATION SCIENCE, Issue 2 2005
F. Louault
Abstract. Question: How do functional types respond to contrasting levels of herbage use in temperate and fertile grasslands? Location: Central France (3°1'E, 45°43'N), 870 m a.s.l. Methods: Community structure and the traits of dominant plant species were evaluated after 12 years of contrasted grazing and mowing regimes in a grazing trial, comparing three levels of herbage use (high, medium and low). Results and Conclusions: Of 22 measured traits (including leaf traits, shoot morphology and composition, phenology), seven were significantly affected by the herbage use treatment. A decline in herbage use reduced individual leaf mass, specific leaf area and shoot digestibility, but increased leaf C and dry matter contents. Plants were taller, produced larger seeds and flowered later under low than high herbage use. Nine plant functional response types were identified by multivariate optimization analysis; they were based on four optimal traits: leaf dry matter content, individual leaf area, mature plant height and time of flowering. In the high-use plots, two short and early flowering types were co-dominant, one competitive, grazing-tolerant and moderately grazing-avoiding, and one grazing-avoiding but not -tolerant. Low-use plots were dominated by one type, neither hardly grazing-avoiding nor grazing-tolerant, but strongly competitive for light. [source]

Phosphorus nutrition-mediated effects of arbuscular mycorrhiza on leaf morphology and carbon allocation in perennial ryegrass

NEW PHYTOLOGIST, Issue 2 2005
Agustín A. Grimoldi
Summary ,,The aim of this work was to disentangle phosphorus status-dependent and -independent effects of arbuscular mycorrhizal fungus (AMF) on leaf morphology and carbon allocation in perennial ryegrass (Lolium perenne). ,,To this end, we assessed the P-response function of morphological components in mycorrhizal and nonmycorrhizal plants of similar size. ,,AMF (Glomus hoi) stimulated relative P-uptake rate, decreased leaf mass per area (LMA), and increased shoot mass ratio at low P supply. Lower LMA was caused by both decreased tissue density and thickness. Variation in tissue density was almost entirely caused by variations in soluble C, while that in thickness involved structural changes. ,,All effects of AMF were indistinguishable from those mediated by increases in relative P-uptake rate through higher P-supply rates. Thus the relationships between relative P-uptake rate, leaf morphology and C allocation were identical in mycorrhizal and nonmycorrhizal plants. No evidence was found for AMF effects not mediated by changes in plant P status. [source]

Nutrient Limitation and Stoichiometry of Carnivorous Plants

PLANT BIOLOGY, Issue 6 2006
A. M. Ellison
Abstract: The cost-benefit model for the evolution of carnivorous plants posits a trade-off between photosynthetic costs associated with carnivorous structures and photosynthetic benefits accrued through additional nutrient acquisition. The model predicts that carnivory is expected to evolve if its marginal benefits exceed its marginal costs. Further, the model predicts that when nutrients are scarce but neither light nor water is limiting, carnivorous plants should have an energetic advantage in competition with non-carnivorous plants. Since the publication of the cost-benefit model over 20 years ago, marginal photosynthetic costs of carnivory have been demonstrated but marginal photosynthetic benefits have not. A review of published data and results of ongoing research show that nitrogen, phosphorus, and potassium often (co-)limit growth of carnivorous plants and that photosynthetic nutrient use efficiency is 20 - 50 % of that of non-carnivorous plants. Assessments of stoichiometric relationships among limiting nutrients, scaling of leaf mass with photosynthesis and nutrient content, and photosynthetic nutrient use efficiency all suggest that carnivorous plants are at an energetic disadvantage relative to non-carnivorous plants in similar habitats. Overall, current data support some of the predictions of the cost-benefit model, fail to support others, and still others remain untested and merit future research. Rather than being an optimal solution to an adaptive problem, botanical carnivory may represent a set of limited responses constrained by both phylogenetic history and environmental stress. [source]

Leaves of Lianas and Self-Supporting Plants Differ in Mass per Unit Area and in Nitrogen Content

PLANT BIOLOGY, Issue 3 2000
M. Kazda
Abstract: The aim of this study was to test the hypothesis that the reduction in supporting tissues in climbers compared to self-supporting plants is also true for their leaves, and that climbers generally require higher leaf nitrogen than self-supporting plants to accomplish fast growth. This hypothesis was tested using paired samples of both growth forms with assessment of leaf area index above the sampled plants (LAIa) in a tropical rain forest in Gabon. The sampling protocol ensured that within a highly fluctuating low canopy environment, the growth conditions were identical for each pair sampled. The results confirmed the hypothesis. Lianas had significantly lower leaf mass per unit leaf area (LMA) than their supporters. Liana leaves also contained significantly more nitrogen than host tree leaves. The differences in nitrogen concentration between liana and tree leaves reversed for the most shaded sites, when nitrogen was expressed on a leaf area base (Narea). Significant regression between leaf nitrogen and LAIa was found for the climbers on the shaded sites but not for their supporters. This indicated better acclimation of climbers to prevailing light conditions. Better nitrogen allocation at low LMA, together with lower carbon costs for building supporting tissues, makes lianas highly competitive, especially where high nitrogen availability is assured. [source]

Acclimation of photosynthetic capacity to irradiance in tree canopies in relation to leaf nitrogen concentration and leaf mass per unit area

PLANT CELL & ENVIRONMENT, Issue 3 2002
P. Meir
Abstract The observation of acclimation in leaf photosynthetic capacity to differences in growth irradiance has been widely used as support for a hypothesis that enables a simplification of some soil-vegetation-atmosphere transfer (SVAT) photosynthesis models. The acclimation hypothesis requires that relative leaf nitrogen concentration declines with relative irradiance from the top of a canopy to the bottom, in 1 : 1 proportion. In combination with a light transmission model it enables a simple estimate of the vertical profile in leaf nitrogen concentration (which is assumed to determine maximum carboxylation capacity), and in combination with estimates of the fraction of absorbed radiation it also leads to simple ,big-leaf' analytical solutions for canopy photosynthesis. We tested how forests deviate from this condition in five tree canopies, including four broadleaf stands, and one needle-leaf stand: a mixed-species tropical rain forest, oak (Quercus petraea (Matt.) Liebl), birch (Betula pendula Roth), beech (Fagus sylvatica L.) and Sitka spruce (Picea sitchensis (Bong.) Carr). Each canopy was studied when fully developed (mid-to-late summer for temperate stands). Irradiance (Q, µmol m,2 s,1) was measured for 20 d using quantum sensors placed throughout the vertical canopy profile. Measurements were made to obtain parameters from leaves adjacent to the radiation sensors: maximum carboxylation and electron transfer capacity (Va, Ja, µmol m,2 s,1), day respiration (Rda, µmol m,2 s,1), leaf nitrogen concentration (Nm, mg g,1) and leaf mass per unit area (La, g m,2). Relative to upper-canopy values, Va declined linearly in 1 : 1 proportion with Na. Relative Va also declined linearly with relative Q, but with a significant intercept at zero irradiance (P < 0·01). This intercept was strongly related to La of the lowest leaves in each canopy (P < 0·01, r2 = 0·98, n= 5). For each canopy, daily lnQ was also linearly related with lnVa(P < 0·05), and the intercept was correlated with the value for photosynthetic capacity per unit nitrogen (PUN: Va/Na, µmol g,1 s,1) of the lowest leaves in each canopy (P < 0·05). Va was linearly related with La and Na(P < 0·01), but the slope of the Va : Na relationship varied widely among sites. Hence, whilst there was a unique Va : Na ratio in each stand, acclimation in Va to Q varied predictably with La of the lowest leaves in each canopy. The specific leaf area, Lm(cm2 g,1), of the canopy-bottom foliage was also found to predict carboxylation capacity (expressed on a mass basis; Vm, µmol g,1 s,1) at all sites (P < 0·01). These results invalidate the hypothesis of full acclimation to irradiance, but suggest that La and Lm of the most light-limited leaves in a canopy are widely applicable indicators of the distribution of photosynthetic capacity with height in forests. [source]

Photosynthetic acclimation of plants to growth irradiance: the relative importance of specific leaf area and nitrogen partitioning in maximizing carbon gain

PLANT CELL & ENVIRONMENT, Issue 8 2001
J. R. Evans
Abstract Changes in specific leaf area (SLA, projected leaf area per unit leaf dry mass) and nitrogen partitioning between proteins within leaves occur during the acclimation of plants to their growth irradiance. In this paper, the relative importance of both of these changes in maximizing carbon gain is quantified. Photosynthesis, SLA and nitrogen partitioning within leaves was determined from 10 dicotyledonous C3 species grown in photon irradiances of 200 and 1000 µmol m,2 s,1. Photosynthetic rate per unit leaf area measured under the growth irradiance was, on average, three times higher for high-light-grown plants than for those grown under low light, and two times higher when measured near light saturation. However, light-saturated photosynthetic rate per unit leaf dry mass was unaltered by growth irradiance because low-light plants had double the SLA. Nitrogen concentrations per unit leaf mass were constant between the two light treatments, but plants grown in low light partitioned a larger fraction of leaf nitrogen into light harvesting. Leaf absorptance was curvilinearly related to chlorophyll content and independent of SLA. Daily photosynthesis per unit leaf dry mass under low-light conditions was much more responsive to changes in SLA than to nitrogen partitioning. Under high light, sensitivity to nitrogen partitioning increased, but changes in SLA were still more important. [source]

Spatial distribution and prediction of seed production by Eucalyptus microcarpa in a fragmented landscape

AUSTRAL ECOLOGY, Issue 1 2010
PETER A. VESK
Abstract Woodlands worldwide have been greatly modified by clearing for agriculture, and their conservation and restoration requires understanding of tree recruitment processes. Seed production is one possible point of recruitment failure, and one that the spatial arrangement of trees may affect. We sampled 118 Eucalyptus microcarpa (Myrtaceae) trees to compare and analyse the determinants of seed production in this dominant tree of modified, fragmented temperate grassy woodlands, which extend over much of southeastern Australia. Fecundity was estimated as the seed crop measured on leaf mass and whole tree bases and was compared between categories of tree configuration. We also modelled fecundity using boosted regression trees, a new and flexible tool. Fecundity on a leaf mass basis was predominantly influenced by environmental factors (topographic ,wetness', slope, soil type), rather than by local tree density and configuration. Fewer seed per unit leaf mass were produced on flat and topographically wet sites, reflecting poor tolerance of waterlogging by E. microcarpa. By contrast, whole tree fecundity was little influenced by environmental factors. Local tree density and configuration did influence whole tree fecundity, which was high in solitary and woodland-spaced trees and reduced under high local density. We found little evidence for reduced fecundity of E. microcarpa in solitary trees. This points to the importance of scattered trees as sources of seed for tree recruitment and for natural regeneration of landscape level tree cover. Considerable uncertainty remains in modelled seed supply, and may be reduced with sampling across multiple years and greater environmental and spatial domains. [source]

Scaling-up from leaf to canopy-aggregate properties in sclerophyll shrub species

AUSTRAL ECOLOGY, Issue 3 2006
CASSIA READ
Abstract: Plant species vary widely in their average leaf lifespan (LL) and specific leaf area (SLA, leaf area per dry mass). The negative LL,SLA relationship commonly seen among species represents an important evolutionary trade-off, with higher SLA indicating greater potential for fast growth (higher rate of return on a given investment), but longer LL indicating a longer duration of the revenue stream from that investment. We investigated how these leaf-economic traits related to aggregate properties of the plant crown. Across 14 Australian sclerophyll shrub species, those with long LL accumulated more leaf mass and leaf area per unit ground area. Light attenuation through their canopies was more severe. Leaf accumulation and light attenuation were more weakly related to SLA than to LL. The greater accumulation of foliage in species with longer LL and lower SLA may counterbalance their generally lower photosynthetic rates and light-capture areas per gram of leaf. [source]

Colonization Strategies of Two Liana Species in a Tropical Dry Forest Canopy

BIOTROPICA, Issue 3 2007
Gerardo Avalos
ABSTRACT Lianas impose intense resource competition for light in the upper forest canopy by displaying dense foliage on top of tree crowns. Using repeated access with a construction crane, we studied the patterns of canopy colonization of the lianas Combretum fruticosum and Bonamia trichantha in a Neotropical dry forest in Panama. Combretum fruticosum flushed leaves just before the rainy season, and its standing leaf area quickly reached a peak in the early rainy season (May,June). In contrast, B. trichantha built up foliage area continuously throughout the rainy season and reached a peak in the late rainy season (November). Both species displayed the majority of leaves in full sun on the canopy surface, but C. fruticosum displayed a greater proportion of leaves (26%) in more shaded microsites than B. trichantha (12%). Self-shading within patches of liana leaves within the uppermost 40,50 cm of the canopy reduced light levels measured with photodiodes placed directly on leaves to 4,9 percent of light levels received by sun leaves. Many leaves of C. fruticosum acclimated to shade within a month following the strongly synchronized leaf flushing and persisted in deep shade. In contrast, B. trichantha produced short-lived leaves opportunistically in the sunniest locations. Species differences in degree of shade acclimation were also evident in terms of structural (leaf mass per area, and leaf toughness) and physiological characters (nitrogen content, leaf life span, and light compensation point). Contrasting leaf phenologies reflect differences in light exploitation and canopy colonization strategies of these two liana species. RESUMEN Las lianas imponen una competencia intensa por la luz en el dosel superior al desplegar un denso follaje encima de las copas de los árboles. Usando acceso repetido al dosel a través de una grúa de construcción, estudiamos los patrones de colonización del dosel de las lianas Combretum fruticosum y Bonamia trichantha en un bosque neotropical seco en Panamá. Combretum fruticosum produjo hojas nuevas justo antes de la estación lluviosa, y su área foliar total alcanzó rápidamente un pico a inicios de la estación lluviosa (mayo-junio). En contraste, B. trichantha construyó su área foliar de forma continua a través de la estación lluviosa alcanzando un pico al final de esta (noviembre). Ambas especies desplegaron la mayoría de sus hojas bajo alta irradiación en la superficie del dosel, aunque C. fruticosum desplegó una mayor proporción de follaje (26%) en micrositios más sombreados que B. trichantha (12%). El auto sombreo dentro de los parches de hojas de lianas dentro de los primeros 40-50 cm del dosel superior redujo el nivel de radiación medido con fotodiodos colocados directamente sobre las hojas a 4-9% de la luz recibida por las hojas de sol. Muchas hojas de C. fruticosum se aclimataron a la sombra luego de un mes después de la producción inicial de hojas altamente sincronizada y persistieron en sombra profunda. En contraste, B. trichantha produjo hojas de corta longevidad de forma oportunística bajo las condiciones de mayor irradiación. Las diferencias entre especies en el grado de aclimatación a la sombra fueron evidentes en términos de caracteres estructurales (masa foliar por unidad de área, y dureza foliar) y fisiológicos (contenido de nitrógeno, longevidad foliar, y punto de compensación lumínica). Estas fenologías foliares tan contrastantes reflejan diferencias en las estrategias de explotación de luz y colonización del dosel por parte de estas dos lianas. [source]