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The Legacy of the Past Logging: How Forest Structure Affects Different Facets of Understory Plant Diversity in Abandoned Coppice Forests
Full text linkPredicting how biodiversity affects ecosystem functioning requires a multifaceted approach based on the partitioning of diversity into its taxonomic and functional facets and thus redundancy. Here, we investigated how species richness (S), functional diversity (FD) and functional redundancy (FR) are affected by forest structure. Sixty-eight abandoned coppice-with-standards plots were selected in two mountain areas of the Apennine chain. We performed linear models to quantify the influence of structural parameters on S, FD and FR of clonal traits. Each diversity facet was affected differently by structural parameters, suggesting a complex interweaving of processes that influence the understory layer. Namely, tree layer density influences S, the height of the standards affects the lateral spread and persistence of clonal growth organs, and diameter of standards affects the FD of the number of clonal offspring. Opposite relationships compared to FD was found for the FR, suggesting how clonal traits play a key role in species assemblage. The observation that structural parameters exert opposite impact on FR seems to indicate a counterbalance effect on ecosystem stability. Multifaceted approaches yield a better understanding of relationship between forest structure and understory, and this knowledge can be exploited to formulate indications for more sustainable management practices
Understory functional response to different management strategies in Mediterranean beech forests (central Apennines, Italy)
No full textThe aim of this paper was to investigate the functional composition of the understory of Mediterranean beech forest stands that have been managed in two different ways, namely, coppicing and tree by tree harvesting. In particular, we used a trait-based approach to characterize old coppice and high forest stands, analyzing their differences and evaluating the status of old coppices by considering their conversion towards high forest stands. The study area was the Montagne della Duchessa massif in central Italy, which lies at the center of the Apennine chain. Sixty-six plots were laid out and their species abundance and structural parameters were recorded. Data on plant traits were collected using both European databases and the literature available. Redundancy analysis was performed to assess the relationship between trait states and management, and forward selection was used to identify the structural parameters with a significant effect on trait variability. A Wilcoxon Rank-Sum test was done to assess differences in trait states between the management types. High forests proved to be more related to traits typical of mature forest conditions, while old coppices seemed not to have a clear trait association, except for some trait states related to open habitats, and showed the same âmature forestâ trait composition, even if with lower abundances. This indicates that, despite the higher initial disturbance pressure, once abandoned, old coppices tend over time to evolve naturally towards mature forest functional conditions
Effect of forest structure and management on the functional diversity and composition of understorey plant communities
No full textQuestions 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 x 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
Community assembly along climatic gradient: Contrasting pattern between- and within- species
No full textGrime's CSR classification of functional strategies in terms of competitors, stress-tolerators and ruderals provides a helpful framework for understanding and predicting vegetation responses to environmental changes. To evaluate the importance of alternative processes that structure plant communities, it is useful to disentangle the community functional variation into interspecific and intraspecific components and assess their degree of covariation. Few efforts have been made to investigate the habitat filtering theory in all the interspecific and intraspecific components of a plant community. We hypothesized that under intense climatic conditions, such as drought and cold, functional diversity would decrease towards the dominance of stress tolerant strategies, and that such trends would be reinforced by similar variation at the intraspecific level. We investigated the effect of climatic variation on functional diversity and on community-weighted mean along an elevation gradient in central Italy that ranges from dry and warm climatic conditions at lower elevation to cold and moist ones at higher elevation. We ran regression models to disentangle the total community components for both functional diversity and community-weighted mean into interspecific effect, intraspecific effect and their covariation along the climatic gradient. Our observations were in line with the theory of habitat filtering: we found lower diversity of the Grime strategy for species at both warmer and colder climatic conditions, with dominance of the stresstolerant strategy. Similarly, the intraspecific effect was lower in cold conditions but higher under drier conditions, which seems to indicate that different processes act at the level of individuals. Given the important intraspecific variability observed in this study, it can be proposed that investigations of vegetation communities should take the role of intraspecific variability into greater consideration
Functional composition and diversity of leaf traits in subalpine versus alpine vegetation in the Apennines
No full textMediterranean high mountain grasslands are shaped by climatic stress and understanding their functional adaptations can contribute to better understanding ecosystems' response to global change. The present work analyses the plant functional traits of high-elevation grasslands growing in Mediterranean limestone mountains to explore, at the community level, the presence of different plant strategies for resource use (conservative vs. acquisitive) and functional diversity syndromes (convergent or divergent). Thus, we compared the functional composition and diversity of the above-ground traits related to resource acquisition strategies of subalpine and alpine calcareous grasslands in the central Apennines, a mountain region characterized by a dry-summer Mediterranean climate. We used georeferenced vegetation plots and field-measured plant functional traits (plant maximum height, specific leaf area and leaf dry matter content) for the dominant species of two characteristic vegetation types: the subalpine Sesleria juncifolia community and the alpine Silene acaulis community. Both communities are of particular conservation concern and are rich in endemic species for which plant functional traits are measured here for the first time. We analysed the functional composition and diversity using the community-weighted mean trait index and the functional diversity using Rao's function, and we assessed how much the observed pattern deviated from a random distribution by calculating the respective standardized effect sizes. The results highlighted that an acquisitive resource use strategy and relatively higher functional diversity of leaf traits prevail in the alpine S. acaulis community, optimizing a rapid carbon gain, which would help overcome the constraints exerted by the short growing season. The divergent functional strategy underlines the co-occurrence of different leaf traits in the alpine grasslands, which shows good adaptation to a microhabitat-rich environment. Conversely, in the subalpine S. juncifolia grassland, a conservative resource use strategy and relatively lower functional diversity of the leaf traits are likely related to a high level resistance to aridity over a longer growing season. Our outcomes indicate the preadaptation strategy of the subalpine S. juncifolia grassland to shift upwards to the alpine zone that will become warmer and drier as a result of anthropogenic climate change
Altitude and aspect filter the herb layer functional structure of sub- Mediterranean forests
No full textQuestion: Do topographic factors that determine the distribution pattern of sub-Mediterranean coppiced
woods influence the functional structure of their herb layer? Study area: Umbria-Marche Apennines (Italy).
Methods: In 156 plots we collected topographic data and species cover. We identified the main forest communities
using a Multivariate Regression Tree (MRT) analysis on the relevés by species matrix constrained by altitude,
aspect and slope angle. For the herb layer of each plot, we calculated the community-weighted mean trait
values (CWMs) and functional diversity (FD) indices. We compared CWM and FD values between MRT
groups at each partition of the tree graph and checked linear trends of CWMs and FD indices along gradients
illustrated by topographic variables and mean Ellenberg’s Indicator Values. Results: Altitude and aspect segregated
the main forest types and filtered the herb layer functional structure, depending on the considered traits.
We observed a shift from strategies related to cold stress and the shortness and unpredictability of growing
season at the highest altitudes and on north-facing slopes, to those related to dryness at lower elevations and on
south-facing slopes. Environmental filtering changed the relative abundance of traits between mountain and
hilly woods, as well as functional richness of life form, vegetative propagation, pollen/spore vector, and functional
evenness, divergence, and Rao’s quadratic entropy of storage organs types. Within hilly forests, functional
divergence increased toward north-facing slopes, while evenness increased toward south-facing slopes.
Conclusions: Altitude and aspect, besides shaping the distribution patterns of sub-Mediterranean coppiced
woods, influence the functional structure of their herb layer in a different manner. In mountain woods, higher
altitude fosters convergence of the storage organs more suitable to tolerate cold stress. In hilly woods, drought
and the heterogeneous distribution of resources on south-facing slopes increase functional evenness, whereas
the higher availability of resources on north-facing slopes promotes divergence
Higher levels of protection do not consistently improve habitat quality: Insights from Mediterranean and Alpine shrublands
Full text linkProtected areas are recognized as a crucial tool to mitigate ongoing trends of biodiversity loss. The effect of different levels of protection and their subsequent conservation efficiency remains, however, largely unexplored. To fill this gap, we present here an integrated approach that combines taxonomic analysis based on typical species to evaluate habitat quality and functional analysis based on plant traits to define habitat structure and functions. We focused on shrubland habitats across levels of protection in two different biogeographical areas. We found that habitat quality does not change linearly with levels of protection. Furthermore, the increase in habitat quality is characterized by a homogenization of habitat structure and functions, mostly driven by an increase in typical species. Our study suggests the level of protection afforded by protected areas is not necessarily indicative of their quality. A combined taxonomic and functional approach in protected areas can offer a thorough appraisal of habitat quality
Context-dependent variation of SLA and plant height of a dominant, invasive tall grass (Brachypodium genuense) in sub-Mediterranean grasslands
No full textThe cessation of semi-extensive farming and the abandonment of settlements are threatening European pastoral landscapes and their biodiversity, affecting species assemblage and ecosystem functioning. This process typically involves invasion by coarse tall grasses, mostly with competitive stress-tolerant strategies, and rapid development of mono-dominance stands. A key species in this respect is Brachypodium genuense (DC.) Roem. et Schult., an endemic, rhizomatous, tall-grass that grows in the semi-natural grasslands of the Italian peninsula over 1200-1400 m a.s.l.
We hypothesized that B. genuense was able to spread and dominate the grassland communities subjected to a wide range of environmental conditions through its broad spectrum of performances. In fact, it has considerable morphological variability, mirrored by high variations of traits, namely Specific Leaf Area (SLA), individual height, and tussock cover values. The study area encompassed the Monti Sibillini National Park (central Italy). We found that in more productive conditions (deeper soil, medium/high pH values, north-facing slopes, and "conservative" landforms) populations of B. genuense had higher SLA, plant height and cover values than in low productive conditions (south-facing slopes, shallow soils, lower pH values). This indicates a fast-growing strategy based on a high rate of resource acquisition and use, as well as high competitive ability for aboveground resources such as light under productive conditions. Under unproductive and/or dry conditions decreased SLA, plant height and cover value indicate a slow growing strategy with high conservation and low rate of resource acquisition. In addition, we found that a very high amount of nitrogen in the soil might have a detrimental effect on B. genuense individuals, decreasing the SLA values, thus requiring the plant to change its growth strategy. Finally, we inferred that the observed variability in SLA might have a paramount role in the invasive/dominant behavior of Brachypodium genuense
Functional traits variation along elevation gradient are climate-context: the case of sub-Mediterranean mountain grasslands
No full textAccording to niche theory environmental factors operate like a filter promoting
the coexistence of species with similar ecological niches. Contrary, competitive
interactions promote niche differentiation increasing functional traits dissimilarity
of co-occurring species. These two processes act simultaneously but given a small study scale, the predominance of one over the other should depend on the intensity
of environmental restrictions. Elevation gradients have been extensively used to test these assumptions, as environmental constrained increase along elevation, mainly
due to temperature decrease. However, in the Mediterranean region precipitation increases
along elevation determining an overall humped-back gradient of environmental restriction,
with higher restriction at the lower and higher elevation. We analysed changes in functional
trait patterns relative to Leaf-Height-Seed scheme along a sub-Mediterranean elevation gradient to test whether community functional patterns responded to this particular environmental gradient. We hypothesized that trait dispersion is higher at middle elevations
and that trait means reflected the communities’ response to environmental restrictions. The study area was carried out on dry grassland of the Velino massif (Central Apennines).
We collected species cover for 45 environmentally homogeneous plots (4 m2) along
and elevation gradient from 1325 to 2375 m a.s.l. To explain changes in functional
patterns at community level, we performed generalized least square models with elevation as explanatory variable, choosing the most appropriate variance structure by the minimum
AIC criteria. We found that all functional indices responded to elevation changes,
except for mean values of specific leaf area. We found at lower and higher elevations, communities displayed adaptation to more environmentally restricted conditions,
i.e. low plant height and low seed mass. Moreover, lower trait diversity values at low
and high elevations indicate that climatic conditions restricted the number of strategies
in the community. On the contrary, more favorable environmental conditions
in the intermediate part of the elevation gradient seems to lead to higher trait diversity.
Our results are in accordance with both niche theory and the stress gradient hypothesis. Nevertheless, the also pin-point the necessity of considering the specific climatic context when trying to generalize the elevation-functional patterns relationships
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