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Leaf Traits (leaf + trait)
Selected AbstractsA multi-trait test of the leaf-height-seed plant strategy scheme with 133 species from a pine forest floraFUNCTIONAL ECOLOGY, Issue 3 2010Daniel C. Laughlin Summary 1.,Westoby's [Plant and Soil (1998), 199, 213] Leaf-Height-Seed (LHS) plant strategy scheme quantifies the strategy of a plant based on its location in a three-dimensional space defined by three functional traits: specific leaf area (SLA), height, and seed mass. This scheme is based on aboveground traits and may neglect strategies of belowground resource capture if root functioning is not mirrored in any of the axes. How then do fine roots fit into the LHS scheme? 2.,We measured 10 functional traits on 133 plant species in a ponderosa pine forest in northern Arizona, USA. This data set was used to evaluate how well the LHS scheme accounts for the variation in above and belowground traits. 3.,The three most important plant strategies were composed of multiple correlated traits, but SLA, seed mass, and height loaded on separate principle components. The first axis reflected the widely observed ,leaf economics spectrum'. Species at the high end of this spectrum had high SLA, high leaf and fine root nitrogen (N) concentration, and low leaf dry matter content. The second axis reflected variation in seed mass and fine root morphology. Plants at the positive end of this spectrum were plants with large seeds and low specific root length (SRL). The third axis reflected variation in height and phenology. Plants at the positive end of this spectrum were tall species that flower late in the growing season. 4.,Leaf N concentration was positively correlated with fine root N concentration. SRL was weakly positively correlated with SLA. SRL was not correlated with fine root N concentration. Leaf litter decomposition rate was positively correlated with the leaf economics spectrum and was negatively correlated with the height and phenology spectrum. 5.,Leaf traits, seed mass, and height appear to be integrating properties of species that reflect much of the variation in plant function, including root function. Fine root N concentration was positively mirrored by the leaf economics spectrum, and SRL was inversely mirrored by seed mass. The leaf and height axes play a role in controlling leaf litter decomposability, indicating that these strategy axes have important consequences for ecosystem functioning. [source] Variation in leaf traits through seasons and N-availability levels and its consequences for ranking grassland speciesJOURNAL OF VEGETATION SCIENCE, Issue 4 2005Raouda Al Haj Khaled Abstract Question: Are leaf dry matter content, specific leaf area and leaf life span relevant plant traits to discriminate the fertility gradient in species-rich natural grasslands? In other words, is species ranking conserved when nitrogen availability or growing periods change? Location: Toulouse Research Centre, France; 150 m a.s.l. Methods: Fifteen grasses and nine dicotyledons were sown in pure stands in a random block design with three replicates. Each species was cultivated at two levels of nitrogen supply, limiting and non-limiting for growth, with three replications per nitrogen level. Leaf traits were measured across both levels of nitrogen supply and growing periods over the year. Results: Leaf dry matter content values separated the species into three life-form classes (grasses, rosette forbs and upright forbs, P < 0.001). This was not the case for specific leaf area and leaf life span. The three leaf traits were variable across growing periods and nitrogen levels, but the ranking of species was conserved over N-levels and growth periods. Furthermore leaf dry matter content was always less variable than the other leaf traits. Conclusion: We conclude that leaf dry matter content measured only on grasses could be used as an indicator to describe the N-richness of the habitat where native herbaceous vegetation develops. [source] Leaf traits as indicators of resource-use strategy in floras with succulent speciesNEW PHYTOLOGIST, Issue 1 2002Fernanda Vendramini Summary ,,Associations between specific leaf area (SLA), leaf water content (LWC) and leaf thickness (LT) in 77 species were analysed to identify which of these traits gave a better indicator value of general plant resource-use strategy within the flora of central-western Argentina, in which succulent species are common. ,,When all species were considered together, SLA and LWC were not significantly correlated. All high-SLA tender-leafed species showed high LWC. Low SLA, however, was associated both with low LWC (sclerophyllous species) and with high LWC (succulents). When succulents were excluded, the association between SLA and LWC was significant and positive. A similar trend was found for a mixed set of nonsucculent species from other floras of the world. ,,In the Argentine data set, SLA and LT, but not LWC, were significantly correlated with species' scores along a multivariate axis of plant resource-use strategy. ,,Because of its clearer ecological interpretation and its applicability across different floras, SLA appears to be the best candidate for inclusion in large comparative databases. [source] Development of early-flowering Kabuli chickpea with compound and simple leavesPLANT BREEDING, Issue 2 2007D. J. Bonfil Abstract Terminal drought is a major constraint to chickpea (Cicer arietinum L.) production. Autumn sowing and early flowering have been suggested as ways to benefit from the winter rains in short rainy seasons under dryland cropping. High-yielding, late-flowering, simple-leafed (slv/slv) chickpea cultivars with good field resistance to Ascochyta blight have been bred recently. Changing plant architecture, by altering leaf shape, may affect agronomic performance. As no information is available on the effect of leaf shape on phenology and seed yield, this study was aimed at: (i) introducing the simple leaf trait into an early-flowering chickpea background; (ii) comparing the grain yield of the two leaf types in early vs. late flowering backgrounds and (iii) producing breeding lines combining early flowering, large seeds and Ascochyta tolerance with both leaf types. Hybrid progeny were studied from the cross of ,Sanford' (slv/slv) and ICC7344, (compound, SLV/SLV). Four early-podding, F8 breeding lines were selected with either simple or compound leaves. In three different field experiments under dryland conditions (334,379 mm), they yielded ca. 1.4 t/ha as compared with 1.0 t/ha in the standard Israeli ,Yarden' on one site, but no significant differences in yield were obtained in the other two experiments. [source] Relationship between post-fire regeneration and leaf economics spectrum in Mediterranean woody speciesFUNCTIONAL ECOLOGY, Issue 1 2009S. Saura-Mas Summary 1Recent work has identified global-scale relationships between key leaf traits (leaf economics spectrum). However, it is important to determine whether this approach can be applied at local scale with smaller subsets of species facing similar environments. Since fire is a key process in Mediterranean shrubland dynamics we analyze whether fire-related life-history traits influence the pattern of correlation between the leaf economic spectrum and leaf moisture traits. 2Using structural equation modelling and exploratory path analysis, we developed alternative models to test how interspecific leaf traits are related to the seasonal variation of water content (leaves and shoots) and to the type of post-fire regeneration of Mediterranean woody species. 3This study demonstrates that for these species seasonal variation in water content and fuel moisture would be better predicted by the presence or absence of a trait describing post-fire seedling establishment than by the leaf economic spectrum traits. However, leaf dry matter content (LDMC) is influenced by both the leaf economic spectrum and the post-fire regenerative type. 4Seeder species (those that recruit via seeds immediately after fire) present lower LDMC and higher relative seasonal variation of relative water content (RWCrsv) than non-seeders. We hypothesize that since seeder species mostly evolved under the Mediterranean climate, they developed a particular strategy of drought tolerance (without causing an effect to the relation between the volume occupied by cytoplasm relative to the volume occupied by cell walls), which is the cause of the observed relation between LDMC and RWCrsv. 5This study suggests that the leaves of Mediterranean woody species would follow the general leaf economics spectrum (Wright et al. 2004) but that specific selective forces, such as disturbance regime, acting at regional scale also play a relevant role to explain leaf traits related to water content. [source] Ecotype adaptation and acclimation of leaf traits to rainfall in 29 species of 16-year-old Eucalyptus at two common gardensFUNCTIONAL ECOLOGY, Issue 6 2006C. R. WARREN Summary 1Relationships of leaf traits with rainfall at the place of origin of seed (RPO) are a function of acclimation and adaptation. To disentangle these effects we studied 29 species of 16-year-old Eucalyptus at a productive and an unproductive common garden (mean annual increments of above-ground stem volume = 21 ± 11 and 8 ± 5 m3 ha,1 years,1, respectively). We tested three hypotheses: (i) leaf traits vary between sites, but relationships among them do not; (ii) relationships of leaf traits with RPO do not vary between sites; and (iii) ecotypes originating from low-rainfall areas allocate a small fraction of nitrogen to thylakoid proteins and Rubisco, and have small SLA, small and narrow leaves, and large water-use efficiency (WUE). 2Eleven leaf traits (leaf area, leaf thickness, leaf width/length, specific leaf area, fresh weight/dry weight, N, chlorophyll a/b, carotenoids/chlorophyll, thylakoid N%, Rubisco N%, WUE derived from 13C content) were measured in 1-year-old sun leaves. 3Site had a large effect on not only the absolute values of leaf traits, but also relationships between pairs of traits. There were 20 significant correlations between pairs of traits. Three of the correlations had different slopes between sites, while a further nine had different intercepts. Hence the majority of significant correlations were not independent of site. 4Leaf area and leaf width/length were the only traits related to RPO. There was no evidence that N allocation to Rubisco or thylakoid proteins was related to RPO, or that WUE was greater in ecotypes from dry areas. 5For Eucalyptus, and perhaps other genera, physiological leaf traits may play a minor role in adaptation to water availability. There is large phenotypic plasticity in many leaf traits affecting not only the absolute values of traits, but also relationships among them. [source] The effect of tree height and light availability on photosynthetic leaf traits of four neotropical species differing in shade toleranceFUNCTIONAL ECOLOGY, Issue 1 2000T. 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] A global study of relationships between leaf traits, climate and soil measures of nutrient fertilityGLOBAL ECOLOGY, Issue 2 2009Jenny C. Ordoñez ABSTRACT Aim This first global quantification of the relationship between leaf traits and soil nutrient fertility reflects the trade-off between growth and nutrient conservation. The power of soils versus climate in predicting leaf trait values is assessed in bivariate and multivariate analyses and is compared with the distribution of growth forms (as a discrete classification of vegetation) across gradients of soil fertility and climate. Location All continents except for Antarctica. Methods Data on specific leaf area (SLA), leaf N concentration (LNC), leaf P concentration (LPC) and leaf N:P were collected for 474 species distributed across 99 sites (809 records), together with abiotic information from each study site. Individual and combined effects of soils and climate on leaf traits were quantified using maximum likelihood methods. Differences in occurrence of growth form across soil fertility and climate were determined by one-way ANOVA. Results There was a consistent increase in SLA, LNC and LPC with increasing soil fertility. SLA was related to proxies of N supply, LNC to both soil total N and P and LPC was only related to proxies of P supply. Soil nutrient measures explained more variance in leaf traits among sites than climate in bivariate analysis. Multivariate analysis showed that climate interacted with soil nutrients for SLA and area-based LNC. Mass-based LNC and LPC were determined mostly by soil fertility, but soil P was highly correlated to precipitation. Relationships of leaf traits to soil nutrients were stronger than those of growth form versus soil nutrients. In contrast, climate determined distribution of growth form more strongly than it did leaf traits. Main conclusions We provide the first global quantification of the trade-off between traits associated with growth and resource conservation ,strategies' in relation to soil fertility. Precipitation but not temperature affected this trade-off. Continuous leaf traits might be better predictors of plant responses to nutrient supply than growth form, but growth forms reflect important aspects of plant species distribution with climate. [source] Evidence for a combination of pre-adapted traits and rapid adaptive change in the invasive plant Centaurea stoebeJOURNAL OF ECOLOGY, Issue 4 2010Martin L. Henery Summary 1. Introduced plants have the potential to rapidly evolve traits of ecological importance that may add to their innate potential to become invasive. During invasions, selection may favour genotypes that are already pre-adapted to conditions in the new habitat and, over time, alter the characteristics of subsequent generations. 2. Spotted knapweed (Centaurea stoebe) occurs in two predominantly spatially separated cytotypes in its native range (Europe,Western Asia), but currently only the tetraploid form has been confirmed in the introduced range (North America), where it is invasive. We used several common garden experiments to examine, across multiple populations, whether tetraploids and diploids from the native range differ in life cycle, leaf traits and reproductive capacity and if such differences would explain the predominance of tetraploids and their advance into new habitats in the introduced range. We also compared the same traits in tetraploids from the native and introduced range to determine whether any rapid adaptive changes had occurred since introduction that may have enhanced invasive potential of the species in North America. 3. We found tetraploids had lower specific leaf area, less lamina dissection and fewer, narrower leaves than diploids. Diploids exhibited a monocarpic life cycle and produced few if any accessory rosettes. Diploids produced significantly more seeds per capitulum and had more capitula per plant than tetraploids. In contrast, the vast majority of European tetraploids continued to flower in both seasons by regenerating from multiple secondary rosettes, demonstrating a predominantly polycarpic life cycle. 4. During early growth tetraploids from North America achieved greater biomass than both tetraploids and diploids from the native range but this did not manifest as larger above-ground biomass at maturity. In North American tetraploids there was also evidence of a shift towards a more strictly polycarpic life cycle, less leaf dissection, greater carbon investment per leaf, and greater seed production per capitulum. 5.,Synthesis. Our results suggest that the characteristics of tetraploid C. stoebe pre-adapted them (compared to diploid conspecifics) for spread and persistence of the species into habitats in North America characterized by a more continental climate. After the species' introduction, small but potentially important shifts in tetraploid biology have occurred that may have contributed significantly to successful invasion. [source] Biomass allocation and leaf life span in relation to light interception by tropical forest plants during the first years of secondary successionJOURNAL OF ECOLOGY, Issue 6 2008N. 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 speciesJOURNAL OF ECOLOGY, Issue 1 2008Elizabeth 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] A community-level test of the leaf-height-seed ecology strategy scheme in relation to grazing conditionsJOURNAL OF VEGETATION SCIENCE, Issue 3 2009Carly Golodets Abstract Question: Is the assumption of trait independence implied in Westoby's (1998) leaf-height-seed (LHS) ecology strategy scheme upheld in a Mediterranean grazing system dominated by annuals? Is the LHS approach applicable at the community level? Location: Northern Israel. Methods: LHS traits (specific leaf area [SLA], plant height and seed mass), and additional leaf traits (leaf dry matter content [LDMC], leaf area, and leaf content of nitrogen [LNC], carbon [LCC], and phosphorus [LPC]), were analyzed at the species and community levels. Treatments included manipulations of grazing intensity (moderate and heavy) and protection from grazing. We focused on species comprising 80% of biomass over all treatments, assuming that these species drive trait relationships and ecosystem processes. Results: At the species level, SLA and seed mass were negatively correlated, and plant height was positively correlated to LCC. SLA, seed mass, and LPC increased with protection from grazing. At the community level, redundancy analysis revealed one principal gradient of variation: SLA, correlated to grazing, versus seed mass and plant height, associated with protection from grazing. We divided community functional parameters into two groups according to grazing response: (1) plant height, seed mass, LDMC, and LCC, associated with protection from grazing, and (2) SLA, associated with grazing. Conclusions: The assumption of independence between LHS traits was not upheld at the species level in this Mediterranean grazing system. At the community level, the LHS approach captured most of the variation associated with protection from grazing, reflecting changes in dominance within the plant community. [source] Leaf dry matter content and lateral spread predict response to land use change for six subalpine grassland speciesJOURNAL OF VEGETATION SCIENCE, Issue 2 2007Nicolas Gross Abstract Question: Land-use change has a major impact on terrestrial plant communities by affecting fertility and disturbance. We test how particular combinations of plant functional traits can predict species responses to these factors and their abundance in the field by examining whether trade-offs at the trait level (fundamental trade-offs) are linked to trade-offs at the response level (secondary trade-offs). Location: Central French Alps. Methods: We conducted a pot experiment in which we characterized plant trait syndromes by measuring whole plant and leaf traits for six dominant species, originating from contrasting subalpine grassland types. We characterized their response to nutrient availability, shading and clipping. We quantified factors linked with different land usage in the field to test the relevance of our experimental treatments. Results: We showed that land management affected nutrient concentration in soil, light availability and disturbance intensity. We identified particular suites of traits linked to plant stature and leaf structure which were associated with species responses to these environmental factors. Leaf dry matter content separates fast and slow growing species. Height and lateral spread separated tolerant and intolerant species to shade and clipping. Discussion and Conclusion: Two fundamental trade-offs based on stature traits and leaf traits were linked to two secondary trade-offs based on response to fertilization shade and mowing. Based on these trade-offs, we discuss four different species strategies which could explain and predict species distributions and traits syndrome at community scale under different land-uses in subalpine grasslands. [source] Variation in leaf traits through seasons and N-availability levels and its consequences for ranking grassland speciesJOURNAL OF VEGETATION SCIENCE, Issue 4 2005Raouda Al Haj Khaled Abstract Question: Are leaf dry matter content, specific leaf area and leaf life span relevant plant traits to discriminate the fertility gradient in species-rich natural grasslands? In other words, is species ranking conserved when nitrogen availability or growing periods change? Location: Toulouse Research Centre, France; 150 m a.s.l. Methods: Fifteen grasses and nine dicotyledons were sown in pure stands in a random block design with three replicates. Each species was cultivated at two levels of nitrogen supply, limiting and non-limiting for growth, with three replications per nitrogen level. Leaf traits were measured across both levels of nitrogen supply and growing periods over the year. Results: Leaf dry matter content values separated the species into three life-form classes (grasses, rosette forbs and upright forbs, P < 0.001). This was not the case for specific leaf area and leaf life span. The three leaf traits were variable across growing periods and nitrogen levels, but the ranking of species was conserved over N-levels and growth periods. Furthermore leaf dry matter content was always less variable than the other leaf traits. Conclusion: We conclude that leaf dry matter content measured only on grasses could be used as an indicator to describe the N-richness of the habitat where native herbaceous vegetation develops. [source] Plant traits and functional types in response to reduced disturbance in a semi-natural grasslandJOURNAL OF VEGETATION SCIENCE, Issue 2 2005F. 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] Foliar demand and resource economy of nutrients in dry tropical forest speciesJOURNAL OF VEGETATION SCIENCE, Issue 1 2001C.B. Lal Important phenological activities in seasonally dry tropical forest species occur within the hot-dry period when soil water is limiting, while the subsequent wet period is utilized for carbon accumulation. Leaf emergence and leaf area expansion in most of these tree species precedes the rainy season when the weather is very dry and hot and the soil cannot support nutrient uptake by the plants. The nutrient requirement for leaf expansion during the dry summer period, however, is substantial in these species. We tested the hypothesis that the nutrients withdrawn from the senescing leaves support the emergence and expansion of leaves in dry tropical woody species to a significant extent. We examined the leaf traits (with parameters such as leaf life span, leaf nutrient content and retranslocation of nutrients during senescence) in eight selected tree species in northern India. The concentrations of N, P and K declined in the senescing foliage while those of Na and Ca increased. Time series observations on foliar nutrients indicated a substantial amount of nutrient resorption before senescence and a ,tight nutrient budgeting'. The resorbed N-mass could potentially support 50 to 100% and 46 to 80% of the leaf growth in terms of area and weight, respectively, across the eight species studied. Corresponding values for P were 29 to 100% and 20 to 91%, for K 29 to 100% and 20 to 57%, for Na 3 to 100% and 1 to 54%, and for Ca 0 to 32% and 0 to 30%. The species differed significantly with respect to their efficiency in nutrient resorption. Such interspecific differences in leaf nutrient economy enhance the conservative utilization of soil nutrients by the dry forest community. This reflects an adaptational strategy of the species growing on seasonally dry, nutrient-poor soils as they tend to depend more or less on efficient internal cycling and, thus, utilize the retranslocated nutrients for the production of new foliage biomass in summer when the availability of soil moisture and nutrients is severely limited. [source] A test of the generality of leaf trait relationships on the Tibetan PlateauNEW PHYTOLOGIST, Issue 4 2006Jin-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] Functional coordination between leaf gas exchange and vulnerability to xylem cavitation in temperate forest treesPLANT CELL & ENVIRONMENT, Issue 4 2006HAFIZ MAHERALI ABSTRACT We examined functional coordination among stem and root vulnerability to xylem cavitation, plant water transport characteristics and leaf traits in 14 co-occurring temperate tree species. Relationships were evaluated using both traditional cross-species correlations and phylogenetically independent contrast (PIC) correlations. For stems, the xylem tension at which 50% of hydraulic conductivity was lost (,50) was positively associated (P < 0.001) with specific conductivity (KS) and with mean hydraulically weighted xylem conduit diameter (Dh-w), but was only marginally (P = 0.06) associated with leaf specific conductivity (KL). The PIC correlation for each of these relationships, however, was not statistically significant. There was also no relationship between root ,50 and root KS in either cross-species or PIC analysis. Photosynthetic rate (A) and stomatal conductance (gs) were strongly and positively correlated with root ,50 in the cross-species analysis (P < 0.001), a relationship that was robust to phylogenetic correction (P < 0.01). A and gs were also positively correlated with stem ,50 in the cross-species analysis (P = 0.02 and 0.10, respectively). However, only A was associated with stem ,50 in the PIC analysis (P = 0.04). Although the relationship between vulnerability to cavitation and xylem conductivity traits within specific organs (i.e. stems and roots) was weak, the strong correlation between gs and root ,50 across species suggests that there is a trade-off between vulnerability to cavitation and water transport capacity at the whole-plant level. Our results were therefore consistent with the expectation of coordination between vulnerability to xylem cavitation and the regulation of stomatal conductance, and highlight the potential physiological and evolutionary significance of root hydraulic properties in controlling interspecific variation in leaf function. [source] Variation in ecophysiology and carbon economy of invasive and native woody vines of riparian zones in south-eastern QueenslandAUSTRAL ECOLOGY, Issue 6 2010OLUSEGUN O. OSUNKOYA Abstract Exotic and invasive woody vines are major environmental weeds of riparian areas, rainforest communities and remnant natural vegetation in coastal eastern Australia, where they smother standing vegetation, including large trees, and cause canopy collapse. We investigated, through glasshouse resource manipulative experiments, the ecophysiological traits that might facilitate faster growth, better resource acquisition and/or utilization and thus dominance of four exotic and invasive vines of South East Queensland, Australia, compared with their native counterparts. Relative growth rate was not significantly different between the two groups but water use efficiency (WUE) was higher in the native species while the converse was observed for light use efficiency (quantum efficiency, AQE) and maximum photosynthesis on a mass basis (). The invasive species, as a group, also exhibited higher respiration load, higher light compensation point and higher specific leaf area. There were stronger correlations of leaf traits and greater structural (but not physiological) plasticity in invasive species than in their native counterparts. The scaling coefficients of resource use efficiencies (WUE, AQE and respiration efficiency) as well as those of fitness (biomass accumulated) versus many of the performance traits examined did not differ between the two species-origin groups, but there were indications of significant shifts in elevation (intercept values) and shifts along common slopes in many of these relationships , signalling differences in carbon economy (revenue returned per unit energy invested) and/or resource usage. Using ordination and based on 14 ecophysiological attributes, a fair level of separation between the two groups was achieved (51.5% explanatory power), with AQE, light compensation point, respiration load, WUE, specific leaf area and leaf area ratio, in decreasing order, being the main drivers. This study suggests similarity in trait plasticity, especially for physiological traits, but there appear to be fundamental differences in carbon economy and resource conservation between native and invasive vine species. [source] Incidence of leaf mining in different vegetation types across rainfall, canopy cover and latitudinal gradientsAUSTRAL ECOLOGY, Issue 3 2008ROBYN J. SINCLAIR Abstract Leaf miners are insects whose larval stages live between layers of leaf epidermis, feeding on mesophyll and lower epidermis to create mine-like cavities. Little is known about the ecology or distribution of leaf miners in Australia. We investigated the incidence of leaf miners in relation to aridity, vegetation types, host plant taxonomy, leaf traits, canopy cover and latitude. We surveyed leaf miners at 15 sites in NSW, eastern Australia, situated along a rainfall gradient from 300 to 1700 mm per annum and a latitudinal gradient of 28°S to 33°S, within four vegetation types (mallee, heath, woodland and rainforest). Leaf mining was recorded from 36 plant species, 89% of which had no previous record of mining. The proportion of mined plant species at each site varied, but there was no significant difference between vegetation types. Leaf mining presence was positively correlated with both total leaf length and leaf thickness. No significant correlations were found between the proportion of mined species at a site and rainfall, latitude or foliar projected cover. We conclude that leaf mining is a widespread type of insect herbivory whose distribution patterns are more likely to be influenced by biotic than abiotic factors. [source] | ||||||||||||||||||||||