1,721,008 research outputs found
Intra-specific multi-trait approach reveals scarce ability in the variation of resource exploitation strategies for a dominant tall-grass under intense disturbance
Full text linkMowing is a suitable practice to restore the grassland coenological composition after invasion of tall-grasses. However, how it affects the tall-grass intraspecific variation is still unknown. We investigated if mowing decreases the competitive ability of the tall-grass Brachypodium rupestre, and if this reduction is due to its poor ability to adapt to the new conditions by reducing resource investment in leaf and flower production, resource storage in belowground organs, increasing seed output and reducing seed mass. In 2017, we measured vegetative and reproductive traits of B. rupestre in two fenced areas in central Apennines (Italy). Half of each area had been mown twice a year since 2010 and half remained unmown. To investigate the effect of mowing on B. rupestre's functional strategies, we used linear mixed-effects modelling and correlation analysis. Mowing significantly reduced the trait values related to competitive ability/resource acquisition (vegetative height and leaf traits), resource storage (mature hypogeogenous rhizome), and sexual reproduction (mean seed mass, number of flowers, reproductive height), but increased seed output. We did not find significant variation of dry matter content in epigeogenous rhizomes and in the shoot number. B. rupestre is not prone to endure a prolonged disturbance, not being able to reallocate resources from acquisitive and retentive to reproductive structures. However, it is able to guarantee the presence of individuals to a certain degree by changing the reproductive strategies, such as decreasing the seed mass and increasing the seed output
How mowing restores montane Mediterranean grasslands following cessation of traditional livestock grazing
Full text linkTraditional land-use cessation allows the spread of invasive tall-grass species and thus leads to a reduction in grassland biodiversity. We hypothesized that long-term multi-year mowing of invaded grassland fosters the recovery of its taxonomic diversity and functional composition by reducing the dominance of the tall grass species Brachypodium rupestre, and that this change increases the pasture feed value. In 2010, we fenced part of a grassland, abandoned for about 30 years, invaded by Brachypodium rupestre (1 ha) in the central Apennine ridge (1,000–1,300 m a.s.l.), and cut it twice a year for six years; another area (1 ha) was fenced and left unmown. Before the experiment started, we recorded species cover in 30 random sampling units (0.5 × 0.5 m) in the experimental area and in the unmown area. The sampling was repeated for the experimental area, every year for six years, except 2013, while it was done for the unmown area only at the end of the six years. We investigated the effect of the reduction of Brachypodium rupestre over time on taxonomic diversity indices, functional traits and pastoral value, using species accumulation curves and generalized linear mixed-effect modelling. Twice-yearly mowing was effective in reducing the abundance of B. rupestre (mean cover 50.7 ± 19.8 % Standard deviation to 9.0 ± 7.2 %), and in increasing significantly species richness (16.6 ± 3.0–26.8 ± 3.2), exponential Shannon (8.8 ± 2.8–14.4 ± 2.7), but not Shannon evenness (0.53 ± 0.1 to 0.54 ± 0.1). At the end of the treatment quite stable richness and diversity values were reached. Reduction of B. rupestre cover increased the pastoral value of the system (39 ± 12 %–64 ± 8 % of pabular species relative cover) and promoted the presence of species without vegetative propagation (17.8 ± 12.3–28.2 ± 10.9), with pleiocorms (25.4 ± 14.3–49.6 ± 17.9), rosettes (5.6 ± 5.6–16.6 ± 12.7) and hemirosettes (32.1 ± 15.8–47.7 ± 13.6), but caused a decrease in species whose clonal growth organs have prevalent vertical spread (123.9 ± 25.7–97.0 ± 23.3), reptant (60.3 ± 20.9–20.2 ± 10.4), and late flowering species (67.4 ± 19.9–46.3 ± 17.2). The decrease of B. rupestre and the increase in mowing frequency reduced the abundance of species with clonal growth organs with prevalent horizontal spread (66.0 ± 19.5–17.9 ± 10.7), caespitose species (96.7 ± 20.9–43.6 ± 21.9), and grasses (94.0 ± 19.5–43.3 ± 22.0). Recurrent twice-yearly mowing seems to be appropriate in the restoration of sub-Mediterranean grasslands invaded by competitive species, facilitating the re-introduction of traditional grazing
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
Effect of forest structure and management on the functional diversity and composition of understorey plant communities
Full text linkQuestions
Do forest structural parameters related to stand heterogeneity enhance functional diversity (FD) of understorey plant communities? Do FD and functional composition of understorey plant communities vary between high-forest (HF) and old coppices-with-standard (oldCWS) management types? Are HF stands characterized by a higher FD than oldCWS?
Location
Submediterranean beech forests of Montagne della Duchessa Reserve (central Italy).
Methods
We sampled 57 (20 m × 20 m) forest plots, 29 oldCWS and 28 HF stands, where we recorded plant species cover abundance. We used Leaf–Height–Seed and clonal traits, and run multiple separate linear models to quantify the effect of forest structural parameters and management types on FD and functional composition of understorey plant communities.
Results
We found that increasing lying deadwood enhanced FD of specific leaf area (SLA) through micro-environmental heterogeneity of soil fertility regardless of management type. We also found that increased horizontal stratification filtered the range of plant sizes, probably through light reduction. HF management enhanced FD of SLA and clonal traits through micro-environmental heterogeneity, while reducing the FD of plant size and seed mass. HF tended to select plant communities characterized by high resource acquisition strategies but lower persistence between ramets, possibly as an effect of more mature forest conditions.
Conclusion
Our study suggests that understorey plant community diversity and composition change in response to forest structure and management. Combining Leaf–Height–Seed with clonal traits offers a promising framework for understanding and predicting plant response to management practices
The role of inter-and intraspecific variations in grassland plant functional traits along an elevational gradient in a mediterranean mountain area
Full text linkElevational gradients offer special opportunities to investigate the relative role of intraspecific and interspecific trait variations in relation to stress gradients. We used an altitudinal gradient in the Mediterranean (Mt Velino, Central Italy) to study (1) how community-weighted means (CWM) and nonweighted means (CM) vary with elevation for plant height, specific leaf area, and seed mass; and (2) how variation patterns differ for inter-and intraspecific functional variability. We tested (1) if elevation influences community functional composition on the basis of the adaptive value of plant traits and (2) if the latter shows intraspecific variations according to the species’ ability to cope with local conditions. We found that different traits showed different patterns, which can be linked to the function they express. Differences between communities were influenced more by differences between their traits (CM) than by the relative species coverage (CWM). Both highest and lowest elevations were the most selective due to their particularly severe climatic conditions. Inter-mediate elevations were the most favorable thanks to less constraining climatic conditions. Interspecific trait variability was the most relevant component, indicating a low plant ability to cope with environmental variations through phenotypic plasticity
Functional response of an invasive tall grass (Brachypodium genuense) to environmental variability in sub-Mediterranean climate
Full text linkWe found that in more productive conditions (deeper soil, medium/high pH values, northfacing
slopes, and “conservative” land forms) populations of B. genuense showed higher
SLA, plant height and cover values. This underlies a fast-growing strategy based on high
resource acquisition/use rate, as well as higher competitive ability for above-ground
resources (e.g. light). The opposite trend emerged for unproductive/dry conditions (southfacing
slopes, shallow soils, lower pH values). Under these constraints, SLA, plant height
and cover value decreased underlying a slow-growing strategy with high conservation and
low acquisition rate of resource. In addition, we found that very high nitrogen amount might
have a detrimental effect on B. genuense individuals decreasing the SLA values, thus
requiring the plant to change the growth strategy
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
Functional variation of Brachypodium genuense (DC) Roem et Schult in sub-Mediterranean grassland
No full textWe hypothesized that B. genuense was able to spread and dominate the sub-Mediterranean grassland communities (Monti Sibillini, central Italy) subjected to a wide range of environmental conditions, thanks to its broad spectrum of performances. In fact, it showed large plasticity, mirrored by high variations of Specific Leaf Area (SLA), plant height and tussock cover values. We found that in more productive conditions (deeper soil, medium/high pH values, northfacing slopes, and “conservative” landforms) populations of B. genuense had higher SLA, plant height and cover values. This underlies a fast-growing strategy based on high resource rate of acquisition and use, as well as higher competitive ability for aboveground resources (e.g. light). In unproductive/dry conditions (south-facing slopes, shallow soils, lower pH values) B. genuense had lower SLA, plant height and cover values, underlying a slow-growing strategy with low rate of resource acquisition and high rate of resource conservation. In addition, we found that very high nitrogen amount might have a detrimental effect on B. genuense individuals decreasing the SLA values, thus requiring the plant to change the growth strategy. We also inferred that the invasive/dominant behavior of competitive-stress tolerant tall grasses is related not only to clonal integration strategy, plant height, litter deposition, etc., but also to the morphological plasticity of leaves, allowing plants to maintain the coordination of multiple resource capture and, hence, to sustain dominance
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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