1,720,974 research outputs found
Beyond the Concept of Winter-Summer Leaves of Mediterranean Seasonal Dimorphic Species
Full text linkThe triangular space of abiotic stress tolerance in woody species: a unified trade-off model
No full textTolerance of abiotic stress in woody plants is known to be constrained by biological trade-offs between different forms of stress, especially shade and drought. However, there is still considerable uncertainty on the relationship between tolerances and the limits on tolerance combinations.
Using the most extensive database available on shade, drought, waterlogging and cold tolerance for 799 northern hemisphere woody species, we determined the number of dimensions needed to summarise their tolerance combinations, and the best trade-off model among those currently available, for description of the interdependence between tolerances.
Two principal component analysis (PCA) dimensions summarised stress tolerance combinations. They defined a triangular stress tolerance space (STS). The first STS dimension reflected segregation between drought-tolerant and waterlogging-tolerant species. The second reflected shade tolerance, which is independent of the other tolerances. Cold tolerance scaled weakly with both dimensions. Tolerance combinations across the species in the database were limited by boundary-line trade-offs.
The STS reconciles all major theories about trade-offs between abiotic stress tolerances, providing a unified trade-off model and a set of coordinates that can be used to examine how other aspects of plant biology, such as plant functional traits, change within the limits of abiotic stress tolerance
Leaf physiological and structural plasticity of two Asplenium (Aspleniaceae) species coexisting in sun and shade conditions
No full textBackground and aims – Relatively few studies have addressed the sun-shade response of fern species.
Moreover, there is no information on species-specific plasticity patterns of such response, their relationship
with species ecological requirements and the costs of such plasticity. The present study aims at filling these
gaps by analysing the sun-shade plastic response of two Asplenium species that differ in their ecological
requirements.
Methods – We measured 27 leaf morphological, anatomical and physiological parameters using standard
methods for A. ceterach and A. trichomanes in the field. The parameters were combined through Principal
Component Analysis in order to highlight an integrated sun-shade response across species. Linear regression
analysis was carried out to highlight the relationship between the calculated species plasticity patterns and
the structural control on photosynthetic process.
Key results – A significant degree of phenotypic plasticity was found for both species. Moreover, sun and
shade leaves shared a common slope for the morpho-functional relationships reflecting no additional costs
in terms of carbon assimilation. Even if the plastic responses of the two species scaled positively (R2 = 0.68,
P = 4.667e‒07), A. trichomanes was characterized by a slightly higher anatomical plasticity (plasticity
index = 0.19), while A. ceterach showed a higher physiological plasticity (0.60).
Conclusion – A remarkable acclimation capacity for the two Asplenium species in response to different
light conditions was highlighted. Nevertheless, A. ceterach seems to be more suited to cope with full
sunlight conditions as compared to A. trichomanes, according to species ecological requirements
Diachronic adjustments of functional traits scaling relationships to track environmental changes. Revisiting Cistus species leaf cohort classification
No full textLeaf functional traits and their relationships can differ between leaf flushes, particularly for species characterized by an extended growing season such as Mediterranean ones. Among them, Cistus spp. are generally reported to display two different leaf cohorts (i.e. summer and winter leaves) during the same growing season. We tested the generality of such leaf cohort classification by analyzing the diachronic adjustments of relationships between different leaf functional traits in 3 Cistus spp. Traits included were: leaf mass per area (LMA), leaf thickness (LT), leaf dry matter content (LDMC) and net photosynthesis on a mass basis (Am). The slopes of the relationships between morphological traits were then regressed against climate variables. The slopes were also regressed against leaf production rate (LPR) and the scores of the positioning as Competitors (%C), Stress tolerators (%S) and Ruderals (%R) in the tertiary CSR scheme. The different leaf flushes reshaped the well-known trait covariation patterns thus reflecting shifts in leaf-level resource-acquisition and -use strategies. This was achieved through an opposite response of the relationships LMA–LT and LMA–LDMC to temperature changes. In fact, the relationship LMA–LT was better modulated in leaves produced at different temperatures, while the LMA–LDMC one was possibly constrained due to the tighter negative relationship LDMC–Am (i.e. higher costs in terms of carbon assimilation). Accordingly, changes in LMA–LDMC coordination were significantly related to %C. Our results provide an evidence that while Cistus spp. leaf cohort classification generally holds, it does not necessarily capture the entire seasonal spectrum of traits covariation. We propose to move forward from the generally accepted winter–summer leaf classification shown in literature providing a new framework that can better describe Cistus species potential response to environmental changes
ITV-net: leveraging intraspecific trait variability to bridge vegetation science and trait-based research in Italy
No full textVegetation science is a branch of community ecology that relies on species identities and abundance to classify vegetation in coherent units and to explore species coexistence and turnover dynamics. The advent of trait-based ecology has expanded vegetation science, providing a framework that allows for a better understanding of plant strategies and the functional structure of communities. These complementary disciplines have remained largely independent among Italian plant ecologists. Therefore, in 2021, we launched the ITV-net initiative, a national collaborative effort for bringing together vegetation plots and field-measured plant trait data to develop a national platform that can serve both vegetation and trait-based ecologists. In the first data call, we were able to gather trait data on two key leaf traits (i.e., Leaf Area and Specific Leaf Area) for >700 species across 1,043 georeferenced vegetation plots, complemented with species relative abundances, across eight different EUNIS habitat types. Despite this remarkable first milestone, we aim to enlarge the scope of this initiative to include more vegetation plots and functional traits across more habitat types in Italy. Here, we provide an overview of the ITV-net initiative and its underlying methodological details as a ‘manifesto’ to spread the data call to other potential contributors in the Italian community of plant ecologists. Our ultimate objective is to bridge the vegetation science and trait-based ecological research in Italy towards developing a national database of vegetation plots and plant functional traits. We believe this effort will contribute to building a solid network among Italian plant ecologists to cross the artificial boundaries of different, yet complementary, disciplines
Leaf mass per area (LMA) as possible predictor of adaptative strategies in two species of Sesleria (Poaceae): analysis of morphological, anatomical and physiological leaf traits
No full textLeaf rolling as indicator of water stress in Cistus incanus from different provenances
Full text linkLeaf movements such as leaf rolling affect plant physiological performance by reducing light capture. The relationship between leaf rolling and physiological traits under imposed water stress conditions was analyzed in two population of Cistus incanus. We tested the hypothesis that leaf rolling reflected physiological changes occurring during water stress irrespective of the different acclimation in order to cope with water stress. On the whole, our results confirmed our hypothesis since leaf rolling significantly reflected physiological activity changes. Moreover, leaf rolling might be involved in protecting the PSII complex under water stress during the progressive inhibition of photosynthetic metabolism. Thus, leaf rolling could be part of C. incanus adaptive strategy to cope with water stress by sustaining leaf turgor. As such, leaf rolling may be used as a morphological index to evaluate the progressive inhibition of photosynthesis irrespective of the different acclimation to cope with water stress
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Specific leaf area variations drive acclimation of Cistus salvifolius in different light environments
No full textCistus salvifolius L. is the most widely spread Cistus species around the Mediterranean basin. It colonizes a wide range of habitats growing from sea level to 1,800 m a.s.l., on silicolous and calcicolous soils, in sun areas as well as in the understory of wooded areas. Nevertheless, this species has been mainly investigated in term of its responsiveness to drought. Our aim was to understand which leaf traits allow C. salvifolius to cope with low-light environments. We questioned if biochemical and physiological leaf trait variations in response to a reduced photosynthetic photon flux density were related to leaf morphological plasticity, expressed by variations of specific leaf area (SLA) and its anatomical components (leaf tissue density and thickness). C. salvifolius shrubs growing along the Latium coast (41°43ʹN,12°18ʹE, 14 m a.s.l., Italy) in the open and in the understory of a Pinus pinea forest, were selected and the relationships between anatomical, gas exchange, chlorophyll (Chl) fluorescence, and biochemical parameters with SLA and PFD variations were tested. The obtained results suggested long-term acclimation of the selected shrubs to contrasting light environments. In high-light conditions, leaf nitrogen and Chl contents per leaf area unit, leaf thickness, and Chl a/b ratio increased, thus maximizing net photosynthesis, while in shade photosynthesis was downregulated by a significant reduction in the electron transport rate. Nevertheless, the increased pigment-protein complexes and the decreased Chl a/b in shade drove to an increased lightharvesting capacity (i.e. higher actual quantum efficiency of PSII). Moreover, the measured vitality index highlighted the photosynthetic acclimation of C. salvifolius to contrasting light environments. Overall, our results demonstrated the morphological, anatomical, and physiological acclimation of C. salvifolius to a reduced light environment
- …
