共查询到20条相似文献,搜索用时 31 毫秒
1.
In Chilean evergreen temperate forest, fern species of the genus Blechnum occur in diverse microhabitats ranging from large gaps to heavily shaded understoreys. We hypothesised that differences in
the ecological breadth of three co-occurring Blechnum species would be associated with differences in magnitude of ecophysiological responses to light availability. We quantified
the field distribution of each species in relation to diffuse light availability (% canopy openness), and measured in situ
variation in photosynthetic capacity (A), dark respiration (R
d) and specific leaf area (SLA) across the light gradient. The response of SLA of each species was also evaluated in a common
garden in two light conditions (understorey and forest edge). The three Blechnum species differed significantly in the range of light environments occupied (breadth: B. chilense > B. hastatum > B. mochaenum). Despite significant interspecific differences in average A and R
d, the response of these traits to light availability did not differ among species. However, there was significant interspecific
variation in both the mean value and the plasticity of SLA to light availability, the species with least ecological breadth
(B. mochaenum) showing a flatter reaction norm (lower response) than its two congeners. This pattern was also found in the common garden
experiment. The adjustment of leaf morphology (SLA) to light availability appears to be an important mechanism of acclimation
in these Blechnum species. The narrow range of light environments occupied by B. mochaenum may be at least partly attributable to its inability to display phenotypic plasticity in SLA to changes in light availability. 相似文献
2.
The growth, morphology and biomass allocation of 11 liana species (six light-demanding and five shade-tolerant) were investigated by growing plants in three contrasting light environments (i.e., field, forest edge and forest interior). Our objectives were to determine: (1) changes in plant traits at the species level; and (2) differences in light-demanding and shade-tolerant species in response to altered light environment. We found that all seedlings of liana species increased in total biomass, total leaf area, relative growth rate (RGR), net assimilation rate (NAR), height, basal diameter, root length, leaf number, root mass/total plant mass (RMR) and root-to-shoot dry biomass (R/S ratio), and decreased in leaf area ratio (LAR), specific leaf area (SLA), leaf size, stem mass-to-total plant mass ratio (SMR) and leaf mass-to-total plant mass ratio (LMR) with increasing light availability. Under the three light environments, the two types of species differed significantly in total biomass, total leaf area, RGR, NAR, LAR, SLA and leaf number, and not in leaf area. Only light-demanding species differed significantly in height, root length, basal diameter, RMR, SMR, LMR and R/S ratio. The mean plasticity index of growth and biomass allocation were relatively higher than the morphological variables, with significant differences between the two groups. Our results showed that liana species respond differently to changing light environments and that light-demanding species exhibit higher plasticity. Such differences may affect the relative success of liana species in forest dynamics. 相似文献
3.
营养和光照对不同生态幅风毛菊属植物幼苗形态可塑性的影响 总被引:4,自引:0,他引:4
以青藏高原东部4种不同生态幅的风毛菊属植物为试验对象,研究了不同营养和光照条件对风毛菊幼苗相对生长率、根冠比和比叶面积的可塑性影响.结果表明: 营养和光照条件对4个物种幼苗的3个形态特征变化呈现显著影响并存在一定的交互作用.这些形态特征的可塑性及其对营养和光照变化的响应模式存在一定的种间差异.物种与营养、光照的交互作用对风毛菊属幼苗的根冠比和比叶面积(P<0.001)存在一定的显著影响.4种植物幼苗的平均形态表型可塑性指数的大小与其生态分布相关,风毛菊幼苗的平均表型可塑性指数最大(0.71),是分布生境最多的一个物种.风毛菊属植物形态可塑性与其分布生态幅呈一定正相关关系. 相似文献
4.
Our understanding of leaf acclimation in relation to irradiance of fully grown or juvenile trees is mainly based on research involving tropical wet forest species. We studied sun-shade plasticity of 24 leaf traits of 43 tree species in a Bolivian dry deciduous forest. Sampling was confined to small trees. For each species, leaves were taken from five of the most and five of the least illuminated crowns. Trees were selected based on the percentage of the hemisphere uncovered by other crowns. We examined leaf trait variation and the relation between trait plasticity and light demand, maximum adult stature, and ontogenetic changes in crown exposure of the species. Leaf trait variation was mainly related to differences among species and to a minor extent to differences in light availability. Traits related to the palisade layer, thickness of the outer cell wall, and N(area) and P(area) had the greatest plasticity, suggesting their importance for leaf function in different light environments. Short-lived pioneers had the highest trait plasticity. Overall plasticity was modest and rarely associated with juvenile light requirements, adult stature, or ontogenetic changes in crown exposure. Dry forest tree species had a lower light-related plasticity than wet forest species, probably because wet forests cast deeper shade. In dry forests light availability may be less limiting, and low water availability may constrain leaf trait plasticity in response to irradiance. 相似文献
5.
Alfredo O. Saldaña Carolina Hernández Rafael E. Coopman León A. Bravo Luis J. Corcuera 《Ecological Research》2010,25(2):273-281
In Chilean evergreen temperate forest, fern species of the genus Blechnum occur in diverse microhabitats in a light gradient. We hypothesized that differences in the habitat preferences of three
co-occurring Blechnum species would be associated with differences in the magnitude of responses of light capture [chlorophyll (Chl) content] and
use (photosynthetic capacity and performance) to light availability. We measured the abundance, chlorophyll content, photosynthetic
capacity (A), and photosynthetic performance (chlorophyll fluorescence of photosystems I and II) of juvenile individuals of each species
growing in different light levels in the field. While Blechnum magellanicum covers a broad light environments range, B. mochaenum is restricted to shade, and B. penna-marina occupies full sun sites. Despite significant interspecific differences in average total chlorophyll content, this trait did
not differ among species along the light gradient. There was significant interspecific variation in both the mean value and
the plasticity of Chl a:Chl b ratio and A to light availability. While B. penna-marina showed a flatter reaction norm (lower response) of Chl a:Chl b ratio to light availability than its two congeners, B. mochaenum showed a lower response of A to light availability. B. penna-marina and B. magellanicum individuals from open sites had higher light saturation points of the electron transport rate (ETR) of both photosystems
(ETRLSP I and II) and photochemical quenching (qL and NA) than the shade restricted B. mochaenum. Additionally, non-photochemical quenching values for both photosystems (NPQ and ND) were higher in ferns species occurring
in shaded sites. The adjustment of the photosynthetic capacity and performance to light availability appears to be an important
mechanism of acclimation in these three Blechnum species that differ in their habitat preferences across a light gradient. 相似文献
6.
S. Chelli G. Ottaviani E. Simonetti G. Campetella C. Wellstein S. Bartha M. Cervellini R. Canullo 《Plant biology (Stuttgart, Germany)》2021,23(1):212-216
- Forest understorey plants are sensitive to light availability, and different species groups can respond differently to changing light conditions. A plant trait tightly linked to light capture is specific leaf area (SLA). Studies considering the relative role of within‐ and among‐species SLA variation across different species groups (e.g. specialists and generalists) are rarely implemented in temperate forest understories varying in their maturity.
- We examined community‐level SLA patterns of beech forest understories along a light availability gradient, and for habitat specialists and generalists separately. We then disentangled and quantified the contribution of intraspecific trait variability and interspecific trait differences in shaping SLA patterns.
- We revealed that the increase in community‐level SLA with decreasing light availability was primarily driven by beech forest specialists (and, to a lesser extent, by forest generalists), and this pattern was mainly determined by specialists’ high intraspecific variability. Community‐level SLA was therefore formed by different responses at different organizational levels, i.e. within and among species, and for separate species groups.
- This study provides insights into factors shaping the shade tolerance strategy in beech forest understorey plants; specialists persistence under putative less favourable conditions (i.e. high irradiation) may be fostered by their ability to adjust their light capture strategies intraspecifically.
7.
Within- and among-species variation in specific leaf area drive community assembly in a tropical cloud forest 总被引:1,自引:0,他引:1
Specific leaf area (SLA) is a key functional trait reflecting the trade-off between resource capture and conservation, and
has been identified as playing an important role in plant community assembly. Mechanistic models of community assembly state
that the assemblage of species in a local community is controlled by environment filters operating on functional traits. We
measured within- and among-species variation of SLA, and environmental conditions in a tropical cloud forest to explore how
variation in this functional trait contributes to community assembly. SLA variation at the species level was also decomposed
into alpha (within assemblage variation), and beta (across assemblage variation) values. SLA decreased with increasing solar
irradiance (approximated using plant height) within the three study sites, and differed among the three sites both for within-
and among-species comparisons. Mean plot SLA, accounting for both within and among species across the three sites, increased
significantly in relation to air temperature but not local photosynthetic photon flux density and soil total phosphorus. Alpha
SLA decreased with increasing solar irradiance within the three sites and beta SLA differed among the three sites. Our results
clearly demonstrate that light and air temperature are key environmental factors involved in organizing plant species within
and among communities in tropical cloud forests. The strong relationship between both intra- and interspecific variation in
SLA and environmental conditions strongly confirms the role of trait variation in the assembly of plant species in tropical
cloud forest communities via environment filtering related to light availability and air temperature. 相似文献
8.
K. C. Burns 《Diversity & distributions》2004,10(2):105-112
Relationships between the distribution and specific leaf area (SLA: leaf area per unit dry mass) of six heath (Ericaceae) species were investigated along an environmental gradient between peat bogs and conifer forest in British Columbia, Canada. I asked whether patterns in SLA could help to identify the processes shaping plant distributional patterns. Specifically, I assessed whether (i) species’ distributions across the environmental gradient are correlated with SLA (ii) relationships between plant distributional patterns and SLA are similar among bogs with different shrub species (iii) intraspecific patterns in SLA parallel interspecific relationships between distributions and SLA, and (iv) intraspecific patterns are environmentally determined. Results showed that distributional patterns were often correlated with SLA; species with lower SLA were more abundant towards the centre of bogs, while species with higher SLA were more abundant in forest. Intraspecific patterns in SLA paralleled distributional patterns across the gradient; individuals located towards the centre of bogs had lower SLA than those growing in forest. A transplantation experiment showed that plants typically altered their SLA according to local environmental conditions. However, one bog showed no relationship between species’ distributions and SLA. This bog lacked the two species with lowest SLA, which typically occurred at the centre of other bogs. In their absence, species with higher SLA that typically occurred in forest increased in abundance towards the centre of the bog, where they obtained lower values of SLA. Therefore, while distributional patterns were often closely associated with SLA, plasticity in SLA was associated with increased breadth of species’ distributions across the gradient. Overall results indicate SLA may serve as a useful proxy for a range of life history traits to help elucidate the processes structuring plant communities. 相似文献
9.
Leaf size and leaf display of thirty-eight tropical tree species 总被引:1,自引:0,他引:1
Trees forage for light through optimal leaf display. Effective leaf display is determined by metamer traits (i.e., the internode,
petiole, and corresponding leaf), and thus these traits strongly co-determine carbon gain and as a result competitive advantage
in a light-limited environment. We examined 11 metamer traits of sun and shade trees of 38 coexisting moist forest tree species
and determined the relative strengths of intra- and interspecific variation. Species-specific metamer traits were related
to two variables that represent important life history variation; the regeneration light requirements and average leaf size
of the species. Metamer traits varied strongly across species and, in contrast to our expectation, showed only modest changes
in response to light. Intra- and interspecific responses to light were only congruent for a third of the traits evaluated.
Four traits, amongst which leaf size, specific leaf area (SLA), and leaf area ratio at the metamer level (LAR) showed even
opposite intra- and interspecific responses to light. Strikingly, these are classic traits that are thought to be of paramount
importance for plant performance but that have completely different consequences within and across species. Sun trees of a
given species had small leaves to reduce the heat load, but light-demanding species had large leaves compared to shade-tolerants,
probably to outcompete their neighbors. Shade trees of a given species had a high SLA and LAR to capture more light in a light-limited
environment, whereas shade-tolerant species have well-protected leaves with a low SLA compared to light-demanding species,
probably to deter herbivores and enhance leaf lifespan. There was a leaf-size-mediated trade-off between biomechanical and
hydraulic safety, and the efficiency with which species can space their leaves and forage for light. Unexpectedly, metamer
traits were more closely linked to leaf size than to regeneration light requirements, probably because leaf-size-related biomechanical
and vascular constraints limit the trait combinations that are physically possible. This suggests that the leaf size spectrum
overrules more subtle variation caused by the leaf economics spectrum, and that leaf size represents a more important strategy
axis than previously thought.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
Alfredo Saldaña Christopher H. Lusk Wilfredo L. Gonzáles Ernesto Gianoli 《Evolutionary ecology》2007,21(5):651-662
Unlike other species of the genus Blechnum, the fern Blechnum chilense occurs in a wide range of habitats in Chilean temperate rainforest, from shaded forest understories to abandoned clearings
and large gaps. We asked if contrasting light environments can exert differential selection on ecophysiological traits of
B. chilense. We measured phenotypic selection on functional traits related to carbon gain: photosynthetic capacity (A
max), dark respiration rate (R
d), water use efficiency (WUE), leaf size and leaf thickness in populations growing in gaps and understorey environments. We
assessed survival until reproductive stage and fecundity (sporangia production) as fitness components. In order to determine
the potential evolutionary response of traits under selection, we estimated the genetic variation of these traits from clonally
propagated individuals in common garden experiments. In gaps, survival of B. chilense was positively correlated with WUE and negatively correlated with leaf size. In contrast, survival in shaded understories
was positively correlated with leaf size. We found positive directional fecundity selection on WUE in gaps population. In
understories, ferns of lower R
d and greater leaf size showed greater fecundity. Thus, whereas control of water loss was optimized in gaps, light capture
and net carbon balance were optimized in shaded understories. We found a significant genetic component of variation in WUE,
R
d and leaf size. This study shows the potential for evolutionary responses to heterogeneous light environments in functional
traits of B. chilense, a unique fern species able to occupy a broad successional niche in Chilean temperate rainforest. 相似文献
11.
Influence of light and nutrient conditions on seedling growth of native and invasive trees in the Seychelles 总被引:1,自引:0,他引:1
Eva Schumacher Christoph Kueffer Peter J. Edwards Hansjörg Dietz 《Biological invasions》2009,11(8):1941-1954
Several recent studies have shown that plant invasions can occur in resource-poor and relatively undisturbed habitats. It
is, therefore, important to investigate whether and how life-history traits of species invasive in such habitats differ from
those of species that are only invasive in disturbed and resource rich habitats. We compared the growth of seedlings of native
and invasive tree species from nutrient-poor secondary forests in the tropical Seychelles. We hypothesised that the relative
performance of the two groups would change predictably along resource gradients, with native species performing better at
low levels of resource availability and invasive species performing better at higher levels. To test this hypothesis, we performed
a common garden experiment using seedlings of six invasive and seven native tree species grown under three levels of light
(65, 11 and 3.5% of ambient light) and two of nutrients (low and high). Due to large variation among species, differences
in growth rates (RGR) were not significant among seedlings of the native and the invasive species. However, seedlings of the
invasive species showed higher specific leaf areas (SLA) and higher leaf nutrient contents than seedlings of the native species.
They also exhibited greater plasticity in biomass and nutrient allocation (i.e., greater plasticity in LAR, RSR and leaf nutrient
contents) in response to varying resource availability. However, differences between the mean values of these parameters were
generally small compared with variation within groups. We conclude that successful invaders on nutrient-poor soils in the
Seychelles are either stress-tolerant, possessing growth traits similar to those of the native species, or fast-growing but
adapted to nutrient-poor soils. In contrast, the more typical, fast-growing alien species with no particular adaptations to
nutrient-poor soils seem to be restricted to relative nutrient-rich sites in the lowlands. The finding—that some introduced
species thrive in resource-poor habitats—suggests that undisturbed habitats with low resource availability may be less resistant
to plant invasions than was previously supposed. 相似文献
12.
Interspecific Variation in RGR and the Underlying Traits among 24 Grass Species Grown in Full Daylight 总被引:4,自引:0,他引:4
Abstract: A growth analysis was conducted with 24 central European grass species in full daylight to test whether traits underlying interspecific variation in relative growth rate (RGR) are the same in full daylight as they are at lower light, and whether this depends on the ecological characteristics of the studied species, i.e., their requirements with respect to nutrient and light availability.
In contrast to studies with herbaceous species at lower light, net assimilation rate (NAR) contributed more than leaf area ratio (LAR) or specific leaf area (SLA) to interspecific variation in RGR. This was associated with a larger interspecific variation in NAR than found in experiments with lower light. Without the two most shade-tolerant species, however, the contribution of LAR and its components to interspecific variation in RGR was similar or even higher than that of NAR.
Leaf dry matter content correlated negatively with RGR and was the only component of LAR contributing in a similar manner to variation in LAR and RGR. There was a positive correlation between NAR and biomass allocation to roots, which may be a result of nutrient-limited growth. RGR correlated negatively with biomass allocation to leaves. Leaf thickness did not correlate with RGR, as the positive effect of thin leaves was counterbalanced by their lower NAR.
Low inherent RGR was associated with species from nutrient-poor or shady habitats. Different components constrained growth for these two groups of species, those from nutrient-poor habitats having high leaf dry matter content, while those from shady habitats had thin leaves with low NAR. 相似文献
In contrast to studies with herbaceous species at lower light, net assimilation rate (NAR) contributed more than leaf area ratio (LAR) or specific leaf area (SLA) to interspecific variation in RGR. This was associated with a larger interspecific variation in NAR than found in experiments with lower light. Without the two most shade-tolerant species, however, the contribution of LAR and its components to interspecific variation in RGR was similar or even higher than that of NAR.
Leaf dry matter content correlated negatively with RGR and was the only component of LAR contributing in a similar manner to variation in LAR and RGR. There was a positive correlation between NAR and biomass allocation to roots, which may be a result of nutrient-limited growth. RGR correlated negatively with biomass allocation to leaves. Leaf thickness did not correlate with RGR, as the positive effect of thin leaves was counterbalanced by their lower NAR.
Low inherent RGR was associated with species from nutrient-poor or shady habitats. Different components constrained growth for these two groups of species, those from nutrient-poor habitats having high leaf dry matter content, while those from shady habitats had thin leaves with low NAR. 相似文献
13.
亚热带常绿落叶阔叶混交林植物功能性状的种间和种内变异 总被引:1,自引:0,他引:1
不同物种间的功能性状差异是自然生态系统中物种共存的基础, 而物种内个体间的性状变异对物种的共存和分布同样具有重要作用。本文以湖北星斗山自然保护区亚热带常绿落叶阔叶混交林内28种主要树种(通过物种多度排序获得, 其中常绿和落叶树种各14种)为研究对象, 探讨不同叶习性树种的4种功能性状(比叶面积、叶干物质含量、叶面积和比茎密度)在种间和种内的差异程度。结果表明: (1)常绿和落叶树种在4种功能性状上均存在显著差异, 常绿树种的比叶面积和叶面积显著低于落叶树种, 但叶干物质含量和比茎密度则显著高于落叶树种; (2)比叶面积的变化主要来源于叶习性(57.49%), 叶面积变化主要来源于种间(66.80%)和种内变异(27.52%), 叶干物质含量的变化主要来源于种间(38.12%)和种内(33.88%)变异, 但比茎密度的变化主要来源于种内变异(51.50%), 其次为种间变异(32.52%); (3)常绿和落叶树种种间水平的性状相关性可能掩盖各功能性状之间的相关性。种内变异能够显著影响群落间的植物功能性状差异, 但不同功能性状的种内变异程度存在差异。 相似文献
14.
Adaptive values of plasticity in Iris pumila leaf traits (morphological: SLA, specific leaf area; anatomical: SD, stomatal density; LT, leaf thickness; VBN, vascular
bundle number; SW, sclerenchyma width; CW, cuticle width, and physiological: ChlT, total chlorophyll concentration; ChlA/B,
chlorophyll a/b ratio) were tested at three irradiance levels in a growth-room. Siblings from 28 full-sib families from an
open dune site and a woodland understory responded similarly to variation in light availability: SLA gradually increased,
while anatomical and physiological traits decreased with light reduction. In the Dune population, standardized linear selection
gradients were significant for SLA and ChlT at high light, VBN along the entire light gradient, SW at high- and low-, and
ChlA/B at low-irradiance. In the Woods population, the significant standardized linear selection gradients were observed for
SLA and LT at low- and VBN at both high- and low-irradiance. A significant nonlinear selection gradient was recorded for SD
and LT at medium irradiance. Comparisons of the plastic responses to each light quantity with the phenotypes favored by selection
in that environments revealed that only an increased SLA value at low light in the Woods population was ecologically significant
(adaptive). In the Dune population, SD and VBN entailed plasticity costs at low irradiance, while a cost of homeostasis was
recognized for ChlT and ChlA/B at medium light, SD and CW at high- and low-, and SLA at high- and medium-light level. In the
shaded population, CW and ChlA/B incurred plasticity costs at high irradiance, while for ChlT plasticity costs appeared under
medium- and low-light conditions. In all leaf traits, genetic variation for plasticity was statistically undetectable. Genetic
correlations between these traits were mostly insignificant, implying that they possess a capability for relatively independent
evolution by natural selection across different light environments. 相似文献
15.
Lucas D Gorn Sandra Díaz Vanessa Minden Yusuke Onoda Koen Kramer Christopher Muir Sean T Michaletz Sandra Lavorel Joanne Sharpe Steven Jansen Martijn Slot Eduardo Chacon Gerhard Boenisch 《Annals of botany》2022,129(6):709
Background and AimsThe acquisitive–conservative axis of plant ecological strategies results in a pattern of leaf trait covariation that captures the balance between leaf construction costs and plant growth potential. Studies evaluating trait covariation within species are scarcer, and have mostly dealt with variation in response to environmental gradients. Little work has been published on intraspecific patterns of leaf trait covariation in the absence of strong environmental variation.MethodsWe analysed covariation of four leaf functional traits [specific leaf area (SLA) leaf dry matter content (LDMC), force to tear (Ft) and leaf nitrogen content (Nm)] in six Poaceae and four Fabaceae species common in the dry Chaco forest of Central Argentina, growing in the field and in a common garden. We compared intraspecific covariation patterns (slopes, correlation and effect size) of leaf functional traits with global interspecific covariation patterns. Additionally, we checked for possible climatic and edaphic factors that could affect the intraspecific covariation pattern.Key ResultsWe found negative correlations for the LDMC–SLA, Ft–SLA, LDMC–Nm and Ft–Nm trait pairs. This intraspecific covariation pattern found both in the field and in the common garden and not explained by climatic or edaphic variation in the field follows the expected acquisitive–conservative axis. At the same time, we found quantitative differences in slopes among different species, and between these intraspecific patterns and the interspecific ones. Many of these differences seem to be idiosyncratic, but some appear consistent among species (e.g. all the intraspecific LDMC–SLA and LDMC–Nm slopes tend to be shallower than the global pattern).ConclusionsOur study indicates that the acquisitive–conservative leaf functional trait covariation pattern occurs at the intraspecific level even in the absence of relevant environmental variation in the field. This suggests a high degree of variation–covariation in leaf functional traits not driven by environmental variables. 相似文献
16.
Because of their overwhelming size over other organisms, trees define the structural and energetic properties of forest ecosystems. From grasslands to forests, leaf area index, which determines the amount of light energy intercepted for photosynthesis, increases with increasing canopy height across the various terrestrial ecosystems of the world. In vertically well-developed forests, niche differentiation along the vertical gradient of light availability may promote species coexistence. In addition, spatial and temporal differentiation of photosynthetic traits among the coexisting tree species (functional diversity) may promote complementary use of light energy, resulting in higher biomass and productivity in multi-species forests. Trees have evolved retaining high phenotypic plasticity because the spatial/temporal distribution of resources in forest ecosystems is highly heterogeneous and trees modify their own environment as they increase nearly 1,000 times in size through ontogeny. High phenotypic plasticity may enable coexistence of tree species through divergence in resource-rich environments, as well as through convergence in resource-limited environments. We propose that the breadth of individual-level phenotypic plasticity, expressed at the metamer level (leaves and shoots), is an important factor that promotes species coexistence and resource-use complementarity in forest ecosystems. A cross-biome comparison of the link between plasticity of photosynthesis-related traits and stand productivity will provide a functional explanation for the relationship between species assemblages and productivity of forest ecosystems. 相似文献
17.
The studied evergreen forest dominated by Quercus ilex showed a leaf area index (LAI) of 4.5, of which 61 % was accumulated within the tree layer, 30 % within the shrub layer,
and 9 % within the herb layer. The leaves of all the species were ± horizontally oriented (41°), absorbing a relevant percentage
of incident irradiance. The high LAI drastically modified the quality and quantity of solar radiation on the forest underground.
The spectral distribution of the radiation under the forest was markedly deficient in blue and red wavelengths. The maximum
absorption in these spectral bands was found in spring, when net photosynthetic rate (P
N
) was at its maximum, and in summer, when new leaves reached 90 % of their definitive structure. The vertical radiation profile
showed an evident reduction of the red-far red ratio (R/FR). Radiation quality and quantity influenced leaf physiology and
morphology. Clear differences in leaf size, leaf water content per area (LWC) and specific leaf area (SLA) on the vertical
profile of the forest were observed. All the shrub species showed similar SLA (12.02 m2 kg-1, mean value). The ability to
increase SLA whilst simultaneously reducing leaf thickness maximized the carbon economy. The high chlorophyll (Chl) content
of shrub layer leaves (1.41 g kg-1, mean value) was an expression of shade adaptation. Both leaf morphology and leaf physiology
expressed the phenotypic plasticity. Q. ilex, Phillyrea latifolia and Pistacia lentiscus of the forest shrub layer showed wide differences in leaf structure and function with respect to the same species developing
under strong irradiance (low maquis): a 57 % mean increase of SLA and a 86 % mean decrease of PN. They showed high leaf plasticity.
Leaf plasticity implies that the considered sclerophyllous species has an optimum developmental pattern achieving adaptation
to environments.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
18.
The life span of resource-acquiring organs (leaves, shoots, fine roots) is closely associated with species successional position
and environmental resource availability. We examined to what extent leaf life span is related to inter- and intraspecific
variation in seedling relative growth rate (RGR). We examined relationships between relative growth rate in mass (RGRM) or height (RGRH) and leaf life span, together with classical RGRM components [net assimilation rate (NAR), specific leaf area (SLA), leaf weight ratio (LWR), and leaf area ratio (LAR)] for
seedlings of five hardwood species of different successional position across a wide range of environmental resource availability,
including the presence or absence of leaf litter in shaded forest understory, small canopy gaps, and large canopy gaps. Both
SLA and LAR were negatively correlated with RGRM along the environmental gradient for all species. However, positive correlations were observed among species within microsites,
indicating that these two components cannot consistently explain the variation in RGRM. Both NAR and LWR affect interspecific, but not intraspecific, variation in RGRM. Leaf life span was negatively correlated with either RGRM or RGRH in both inter- and intraspecific comparisons. Species with short-lived, physiologically active leaves have high growth rates,
particularly in resource-rich environments. Consequently, leaf life span is a good predictor of seedling RGR. Leaf life span
affects plant performance and has a strong and consistent effect on tree seedling growth, even among contrasting environments. 相似文献
19.
该文比较了羊草草原群落中包括建群种和优势种在内的6种植物,羊草(Leymus chinensis)、西伯利亚羽茅(Achnatherum sibiricum)、大 针茅(Stipa grandis)、 冰草(Agropyron cristatum)、糙隐子草(Cleistogenes squarrosa)和黄囊苔草(Carex korshinskyi)的比叶 面积(Specific leaf area, SLA)、叶片含氮量和叶绿素含量等叶片功能特性( Leaf functional trait)对氮素添加的响应,旨在探讨草原生态 系统中,不同物种对氮素可利用性改变的响应和适应对策。结果表明:随着氮素添加量的增加,物种对光资源的竞争增强,不同物种在光资源 的竞争策略和竞争力间存在着显著的差异。羊草通过提高SLA、单位质量叶片的叶绿素含量和含氮量,使单位面积叶片含氮量和叶绿素含量均呈 线性提高,进而增强了其对光的竞争力。西伯利亚羽茅主要通过提高SLA增加光合总面积,来增强自身的光竞争力。冰草在SLA和单位质量叶片 的叶绿素和氮含量均有一定的可塑性,但对光的竞争力明显弱于羊草和西伯利亚羽茅。大针茅和黄囊苔草对SLA的调节能力较低,加之大针茅 SLA较低,而黄囊苔草处于群落的下层,这两种植物的光竞争力较弱。糙隐子草具有较高的SLA,对单位质量叶片叶绿素和氮含量的调节能力相 对较强,其光竞争力高于黄囊苔草。同时,糙隐子草叶片叶绿素a与叶绿素b的比值沿氮素添加梯度显著降低,进一步证实氮素添加改变了群落 的光环境。 相似文献
20.
荆条叶性状对野外不同光环境的表型可塑性 总被引:3,自引:0,他引:3
光照是影响植物生长和分布的重要环境因子。对生长在野外5种不同光环境下(林外、阔叶林林缘、阔叶林林下、针叶林林窗和针叶林林下)的荆条的叶片进行取样研究,通过对光合作用光响应曲线、叶绿素荧光、叶绿素含量、叶片氮磷含量以及叶片形态的测量,来反映荆条对不同光环境的表型可塑性。研究结果表明,荆条叶片对于野外不同的光环境具有很好的适应机制,叶片功能性状受到结构性状的调节。低光下通过高的比叶面积(SLA)、单位质量叶绿素含量、光系统II最大量子产量,低的暗呼吸速率、光饱和点、光补偿点、叶绿素a,b的比值来提高对光能的利用效率,维持生长;高光下则通过与SLA有关的叶片结构的变化对光合作用进行调节。大多数的叶性状只受到日光照总量的影响,SLA的大小与日最高光强有关,可以对不同日变化模式的光照做出迅速的响应,是适应不同光照的敏感指标。尽管光照是不同光环境下影响荆条叶性状的主要环境因子,土壤养分含量同样会对叶性状产生影响,高土壤养分下的高叶长与叶柄长的比值体现了植物对资源获取和支撑结构之间分配的权衡。 相似文献