Seasonal and altitudinal changes in leaf nutrient concentrations of Hedera helix L. (Araliaceae) (original) (raw)
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2015
La résorption est l’une des plus importantes stratégies d’utilisation des nutriments développées par les plantes. Le ratio de la surface foliaire à la masse sèche (SLA) est lié aux nutriments foliaires. Dans la présente étude, les changements de concentration en SLA, N et P, le rapport N/P et la teneur en C des feuilles de lumière et d’ombre de la liane sempervirente Hedera helix L. ont été étudiés au long de l’année sur un gradient altitudinal. L’efficience (RE) et l’efficacité (RP) de la résorption foliaire ont également été calculées dans les feuilles de lumière et celles d’ombre. Les traits foliaires ont montré des changements significatifs entre les localités et au cours de l’année. Des différences significatives sont apparues entre les feuilles de lumière et celles d’ombre pour ce qui concerne le SLA, la concentration en N et la teneur en C, mais se sont avérées dépendantes des différences d’altitude. Toutefois, aucune différence significative de concentration en P n’a été tro...
Canadian Journal of Botany, 2001
We examined 90 dry tropical tree species growing on contrasting soil types (relatively infertile Ultisol and more fertile Inceptisol) for leaf traits such as leaf habit, specific leaf mass (SLM, leaf dry mass per leaf area), leaf chemistry (nutrient concentrations and C/N ratios), and nutrient resorption. Across the species, SLM ranged from 4.06 to 15.74 mg·cm -2 in mature leaves and from 2.60 to 15.12 mg·cm -2 in senesced leaves. Mature leaf N and P concentrations varied from 0.86% to 4.11% and 0.13% to 0.21%, respectively. Senesced leaf N concentrations varied from 0.49% to 1.90% and P from 0.04% to 0.47%. Resorption efficiencies varied from 26% to 83% (mean = 58.32% ± 1.20%) for N and from 16% to 80% (mean = 49.57% ± 1.48%) for P indicating that the woody species of dry tropical environments resorbed different nutrients in substantial amounts to support new growth. Deciduous species had greater resorbed nutrient pools and resorption efficiencies than evergreen species. Compared with the nutrient-rich environment, species from the nutrient-poor environment had a lower resorbed P pool and lower resorption efficiencies for N and P, but had similar N and P concentrations in mature leaves. Resorption efficiencies for C, N, and P were generally correlated, suggesting that the resorbed C pool acted as a vehicle for mobilizing nutrients, especially N. Species with a low or high C/N ratio in senesced leaf and a low or high N resorption efficiency occurred in both nutrient-poor and nutrient-rich environments, as well as among deciduous and evergreen leaf habits, indicating individualistic adaptations to optimize the efficiency of nutrient resource use and conservation of the dry tropical woody vegetation.
Écoscience, 2003
Specific leaf area (SLA) is a common variable in comparative plant ecology that is often measured on field-grown plants, yet SLA is known to be a plastic trait. The motivation for this study was therefore to determine the degree to which environmentally induced plasticity in SLA might obscure interspecific trends. Specifically, we tested the hypothesis that SLA is more responsive to nutrient stress at low irradiance than at high irradiance. To test this hypothesis we grew plants of six species of herbaceous Asteraceae in factorial combinations of 500, 250, and 125 µmol m-2 s-1 irradiance and a full strength (1/1), a 1/5, and a 1/10 dilution of a modified Hoagland hydroponic solution. The full strength solution had 8 mM of nitrogen. Plants were harvested at 21, 28, 35, and 42 days from germination. SLA varied significantly between species, harvest dates, and experimental treatments. In general, SLA decreased with age, but more severely at low irradiance. SLA increased with decreasing irradiance. SLA also increased with increasing nutrient concentration, but this effect disappeared in the older plants at the higher irradiance. These trends were not seen in every species. Our hypothesis was supported: SLA is more responsive to nutrient stress at low irradiance than at high irradiance, but the exact response is species-specific. Despite these environmentally induced changes in SLA at the intraspecific level, the interspecific differences were maintained across environments, justifying the use of SLA as a useful trait in comparative plant ecology.
Alnus glutinosa (Betulaceae) has a widespread distribution in the Central Black Sea Region of Turkey. In this study, annual nitrogen (N) and phosphorus (P) and foliar resorption efficiency and proficiency were investigated in A. glutinosa. N and P concentrations were decreased in senescent leaves. Statistically significant differences were found in P concentrations while there were no found significant differences in N concentrations with respect to months. A negative correlation was obtained between SLA and LMA, SLA and N concentrations. However, there were significant correlations between LMA and N concentrations. N and P resorption efficiency (NRE, PRE) and proficiency (NRP, PRP) values were high as compared to the other deciduous species. These results indicate efficient internal cycling of nutrients especially P in A. glutinosa.
ANNALS OF BOTANY, 2002
Young trees 0´03±1´7 m high of three coexisting Betula species were investigated in four sites of varying soil fertility, but all in full daylight, to separate nutrient and plant size controls on leaf dry mass per unit area (M A ), light-saturated foliar photosynthetic electron transport rate (J) and the fraction of plant biomass in foliage (F L ). Because the site effect was generally non-signi®cant in the analyses of variance with foliar nitrogen content per unit dry mass (N M ) as a covariate, N M was used as an explaining variable of leaf structural and physiological characteristics. Average leaf area (S) and dry mass per leaf scaled positively with N M and total tree height (H) in all species. Leaf dry mass per unit area also increased with increasing H, but decreased with increasing N M , whereas the effects were species-speci®c. Increases in plant size led to a lower and increases in N M to a greater F L and total plant foliar area per unit plant biomass (LAR). Thus, the self-shading probably increased with increasing N M and decreased with increasing H. Nevertheless, the whole-plant average M A , as well as M A values of topmost fully exposed leaves, correlated with N M and H in a similar manner, indicating that scaling of M A with N M and H did not necessarily result from the modi®ed degree of within-plant shading. The rate of photosynthetic electron transport per unit dry mass (J M ) scaled positively with N M , but decreased with increasing H and M A . Thus, increases in M A with tree height and decreasing nitrogen content not only resulted in a lower plant foliar area (LAR = F L /M A ), but also led to lower physiological activity of unit foliar biomass. The leaf parameters (J M , N M and M A ) varied threefold, but the whole-plant characteristic F L varied 20-fold and LAR 30-fold, indicating that the biomass allocation was more plastically adjusted to different plant internal nitrogen contents and to tree height than the foliar variables. Our results demonstrate that: (1) tree height and N M may independently control foliar structure and physiology, and have an even greater impact on biomass allocation; and (2) the modi®ed within-plant light availabilities alone do not explain the observed patterns. Although there were interspeci®c differences with respect to the statistical signi®cance of the relationships, all species generally ®t common regressions. However, these differences were consistent, and suggested that more competitive species with inherently larger growth rates also more plastically respond to N and H.
Cientifica, 2008
The effect of plant size (estimated as total dry weight) on leaf growth of Aglaonema commutatum Schott was studied under limited light conditions. Two different plant sizes were used. A significant positive regression was found between leaf area and plant size. However, distinct slope values were detected after production and complete expansion of three new leaves. Despite greater leaf size, there were no significant differences in leaf thickness and leaf tissue distribution between leaves expanded under high-(previous leaves) or low-light for both plant sets. We propose that for a long time under limited light, a decrease in Aglaonema commutatum leaf size would be associated to a reduced photosynthate translocation capacity of the resources stored in other plant organs. The effect of these results on ornamental industry is discussed too.