Unimodal Relationships of Understory Alpha and Beta Diversity along Chronosequence in Coppiced and Unmanaged Beech Forests

Patterns of diversity across spatial scales in forest successions are being overlooked, despite their importance for developing sustainable management practices. Here, we tested the recently proposed U-shaped biodiversity model of forest succession. A chronosequence of 11 stands spanning from 5 to 400 years since the last disturbance was used. Understory species presence was recorded along 200 m long transects of 20 × 20 cm quadrates. Alpha diversity (species richness, Shannon and Simpson diversity indices) and three types of beta diversity indices were assessed at multiple scales. Beta diversity was expressed by a) spatial compositional variability (number and diversity of species combinations), b) pairwise spatial turnover (between plots Sorensen, Jaccard, and Bray–Curtis dissimilarity), and c) spatial variability coefficients (CV% of alpha diversity measures). Our results supported the U-shaped model for both alpha and beta diversity. The strongest differences appeared between active and abandoned coppices. The maximum beta diversity emerged at characteristic scales of 2 m in young coppices and 10 m in later successional stages. We conclude that traditional coppice management maintains high structural diversity and heterogeneity in the understory. The similarly high beta diversities in active coppices and old-growth forests suggest the presence of microhabitats for specialist species of high conservation value

Status and changes of ground vegetation at the CONECOFOR plots, 1999 - 2005

oai:journals.crea.ugov.it:article/901The vegetation dataset (1999-2005) of the CONECOFOR network is analyzed in the paper, to produce a present-day status and evaluation of changes in a sub-set of Permanent Monitoring Plots (PMPs). Descriptors such as mean number of species (community and population scale), diversity indices and species turnover were selected. Each PMP was investigated to evaluate: (i) type and direction of variations; (ii) significant changes of species indicator values. At the community level, significant variations in richness occurred in sites affected by recent anthropic or natural disturbances. In few PMPs directional changes can be observed; in most of cases a typical fluctuation pattern (more or less regular) was detected. The use of a priori reference standard (RS) supported the interpretation of changes. At finer scale (population level), annual richness variations are frequent but of minor importance. Higher values of species turnover occurred in communities under intense dynamic processes, interested by disturbance or influenced by neighboring communities. The abundance of nitrophilous species was consistent in beech forests, while the contribution of acidophilous species was not important. Moreover, our results suggest that: (a) the data collected at the community level seem more sensitive to describe important changes at the forest stand level; (b) a strong relationship is present between plant diversity and the forest dynamical state. The inherent non-linear dynamics of forest regeneration processes emphasizes the needs of long-term datasets for detecting the plant diversity responses to environmental changes

Biogeographic deconstruction of phylogenetic and functional diversity provides insights into the formation of regional assemblages

Evolutionary history and environmental filtering shape the phylogenetic and functional structure of regional assemblages. However, detecting the footprint of such eco-evolutionary drivers is challenging because these may often counter each other's signature. Here, we examined whether a biogeographic deconstruction approach of phylogenetic (PD) and functional diversity (FD) patterns may help in identifying eco-evolutionary signals in extant regional assemblages. As model system, we used forest understorey angiosperms found in three regions of Italy (Alpine, Mediterranean, Continental). We quantified PD and FD of all species inhabiting the three regions (regional assemblages). Then, we computed PD and FD for the subsets of species restricted to each region (biogeographic elements), also examining diversity patterns of species found across the three regions (widespread element). We used aboveground and belowground traits capturing major plant functions to calculate FD. Additionally, we assessed FD patterns decoupled from phylogeny. We found that species restricted to climatically harsh regions (Alpine and Mediterranean elements) were phylogenetically and functionally clustered, whereas widespread species were characterised by overdispersion. Species confined to the climatically intermediate (Continental) region were randomly sorted. By including all species occurring within a region, the patterns found for the region-restricted species blurred. Phylogenetically decoupled FD patterns were qualitatively similar to non-decoupled ones with the exception of the Alpine element, where we detected a clear signature of functional differentiation between closely related species. This suggests that recent speciation events contributed to shaping the Alpine flora. Compared to the belowground compartment, aboveground traits showed a more coherent pattern with that of all-trait FD – likely because most biomass is allocated aboveground in forest understoreys. This biogeographic deconstruction study illustrates which type of eco-evolutionary insights can be gained by implementing multifaceted and integrated approaches at the macroecological scal

Biogeographic deconstruction of phylogenetic and functional diversity provides insights into the formation of regional assemblages

Evolutionary history and environmental filtering shape the phylogenetic and functional structure of regional assemblages. However, detecting the footprint of such eco-evolutionary drivers is challenging because these may often counter each other's signature. Here, we examined whether a biogeographic deconstruction approach of phylogenetic (PD) and functional diversity (FD) patterns may help in identifying eco-evolutionary signals in extant regional assemblages. As model system, we used forest understorey angiosperms found in three regions of Italy (Alpine, Mediterranean, Continental). We quantified PD and FD of all species inhabiting the three regions (regional assemblages). Then, we computed PD and FD for the subsets of species restricted to each region (biogeographic elements), also examining diversity patterns of species found across the three regions (widespread element). We used aboveground and belowground traits capturing major plant functions to calculate FD. Additionally, we assessed FD patterns decoupled from phylogeny. We found that species restricted to climatically harsh regions (Alpine and Mediterranean elements) were phylogenetically and functionally clustered, whereas widespread species were characterised by overdispersion. Species confined to the climatically intermediate (Continental) region were randomly sorted. By including all species occurring within a region, the patterns found for the region-restricted species blurred. Phylogenetically decoupled FD patterns were qualitatively similar to non-decoupled ones with the exception of the Alpine element, where we detected a clear signature of functional differentiation between closely related species. This suggests that recent speciation events contributed to shaping the Alpine flora. Compared to the belowground compartment, aboveground traits showed a more coherent pattern with that of all-trait FD – likely because most biomass is allocated aboveground in forest understoreys. This biogeographic deconstruction study illustrates which type of eco-evolutionary insights can be gained by implementing multifaceted and integrated approaches at the macroecological scal

clonal growth modes in plant communities along a stress gradient in the central apennines italy

A simplification from species to functional groups using the concept of clonality is particularly attractive for predictive modelling of vegetation processes and preparing guidelines for nature conservation. This important functional trait based on a modular structure including resource-acquiring units (ramets, feeding sites) and spacers, has been studied in three plant communities (xeric grassland, mesic grassland, and beech forest) under different levels of environmental stress (related to soil moisture and fertility) in the Montagna di Torricchio Nature Reserve near Camerino, Central Apennines, Italy. The study sought to reveal patterns of clonal growth modes (CGMs) in the three plant community types, and to test a series of hypotheses on the importance of selected CGMs along the stress gradient. Clonality was shown to have different importance in the grassland communities, due to differences in the importance of various CGMs (representing syndromes of clonal traits). Below-ground positioning of CGOs, shorter spacers, higher multiplication potential, permanent physical connection between ramets, large bud bank, and increased importance of bud protection were frequently found in water-stressed xeric grasslands, suggesting the adaptive value of these clonal traits. The major differences between grassland communities were due to the dominant CGMs: turf graminoids (with an effective way of protecting growth meristems in dense tussocks) dominated xeric grasslands, whereas rhizomatous graminoids (typical of competitive resource-rich habitats) dominated mesic grasslands. The beech forest had fewer clonal species (67%) and lower CGM diversity. Based on the assumption that different environments promote different selection pressures, the tests revealed the following results: (1) Plants with clonal organs below ground have significantly higher cover values in stressed habitats. (2) Species with short spacers are more frequent in less favourable environments, and their importance is almost ten times higher in the xeric grassland than in the forest (71% to 7.6%). (3) The number of species able to produce numerous ramets is highest in the most stressed habitat. (4) The number of species with a potential for longlasting connection between ramets increases towards stressed environments. In contrast to our expectations, the mesic grasslands (occupying the central position along the studied stress gradient) have the highest number of species with storage organs. (6) In stressed habitats, species with forms of bud protection were the most frequent

comspat: an R package to analyze within-community spatial organization using species combinations

The diversity of species combinations observable in sampling units reflects a species' uneven distribution and preference for specific abiotic and biotic conditions – a phenomenon most commonly expressed in terms of ecological assembly rules of plant communities and other sessile organisms (e.g. subtidal algae, invertebrates and coral reefs). We present comspat, a new R package that uses grid or transect data sets to measure the number of realized (observed) species combinations (NRC) and the Shannon diversity of realized species combinations (compositional diversity; CD) as a function of spatial scale. NRC and CD represent two measures from a model family developed by Pál Juhász-Nagy based on information theory. Classical Shannon diversity measures biodiversity based on the number and relative abundance of species, whereas the specific version of Shannon diversity presented here characterizes biodiversity and provides information on species coexistence relationships; both measures operate at fine-scale within the sampling unit or within the community. comspat offers two commonly applied null models, complete spatial randomness and random shift, to disentangle the textural, intraspecific and interspecific effects on the observed spatial patterns. Combined, these models assist users in detecting and interpreting spatial associations and inferring assembly mechanisms. Our open-sourced package provides a vignette that describes the method and reproduces the figures from this paper to help users contextualize and apply functions to their data

Intraspecific phenotypic variability of plant functional traits in contrasting mountain grasslands habitats

Empirical studies that link plants intraspecific variation to environmental conditions are almost lacking, despite their relevance in understanding mechanisms of plant adaptation, in predicting the outcome of environmental change and in conservation. Here, we investigate intraspecific trait variation of four grassland species along with abiotic environmental variation at high spatial resolution (n = 30 samples per species trait and environmental factor per site) in two contrasting grassland habitats in Central Apennines (Italy). We test for phenotypic adaptation between habitats, intraspecific trait-environment relationships within habitats, and the extent of trait and environmental variation. We considered whole plant, clonal, leaf, and seed traits. Differences between habitats were tested using ANOVA and ANCOVA. Trait-environment relationships were assessed using multiple regression models and hierarchical variance partitioning. The extent of variation was calculated using the coefficient of variation. Significant intraspecific differences in trait attributes between the contrasting habitats indicate phenotypic adaptation to in situ environmental conditions. Within habitats, light, soil temperature, and the availability of nitrate, ammonium, magnesium and potassium were the most important factors driving intraspecific trait-environment relationships. Leaf traits and height growth show lower variability than environment being probably more regulated by plants than clonal traits which show much higher variability. We show the adaptive significance of key plant traits leading to intraspecific adaptation of strategies providing insights for conservation of extant grassland communities. We argue that protecting habitats with considerable medium- and small-scale environmental heterogeneity is important to maintain large intraspecific variability within local populations that finally can buffer against uncertainty of future climate and land use scenarios

Climate change response of vegetation across climatic zones in Italy

Italy represents a good model region for assessing vegetation responses to changing climate across a broad climatic range, from Mediterranean warm-dry climate to alpine cold-humid climate. We reviewed results of studies analysing the response of natural vegetation to climate change in Italy, published until July 2016 in peer-reviewed journals. Evidence provided by these studies shows that climate warming is expected overall to enhance plant growth in Italy, but the magnitude of growth stimulation will probably vary among climatic zones, with stronger effects in the cold regions of the alpine climatic zone. Drought, induced by reduced precipitation and/or increased evapotranspiration, can override the positive effects of higher temperatures on plant growth, not only in the Mediterranean warm-dry climatic zone but also in the less dry sub-Mediterranean climatic zone and even in the temperate one. Our review highlighted 2 major research gaps to which future research should be directed. First, there is poor knowledge of how species composition will change in response to changing climate and how this will affect ecosystem functioning in Mediterranean to temperate ecosystems. Second, there is poor knowledge of possible interactions between climate-induced vegetation changes and dynamic processes related to land-use changes

The response of sub-Mediterranean grasslands to rainfall variation is influenced by early season precipitation

Question: Climate change will likely modify patterns of precipitation, with an expected increase in intra-annual variability and increased frequency and magnitude of extreme events. The Mediterranean area is expected to be very sensitive to such events because water availability is already limited. However, the effect of precipitation variability on ecosystem services, such as plant productivity, is little known. What is the short-term effect of an experimental precipitation gradient on above-ground net primary productivity (ANPP) of two contrasting sub-Mediterranean grassland ecosystems? How does early season precipitation, i.e. dry or wet spring, influence ANPP? Do the functional groups of grasses and forbs differ in their response?. Location: Torricchio Nature Reserve, Central Apennines, Italy. Methods: We selected two grasslands characterized by contrasting geophysical and soil chemical parameters (north- and south-facing slopes). In both sites, during two climatically different years, mid-season (summer) precipitation was manipulated in order to obtain a gradient of rainfall availability, comprising additional rainfall, ambient rainfall conditions and rainfall reduction. The above-ground biomass, subdivided according to the functional groups of forbs and grasses, was collected at the end of each treatment period. Results: A significant increase in ANPP due to experimental increase in summer rainfall appeared in the year with the wet spring, but only in the mesic north-facing slope. This response was driven by the increased productivity of perennial forbs, while grasses showed stable above-ground production. In contrast, in the year with the dry spring, ANPP did not respond to the experimental rainfall gradient, meaning that a dry spring leads to lower ANPP even under increased summer rainfall. The variability of ANPP increased significantly in the xeric south-facing slope in the year with the wet spring, most likely reflecting indirect effects of small-scale heterogeneity such as variations in soil depth. Conclusions: Intra-annual precipitation variation can have noticeable implications for sub-Mediterranean montane grassland agriculture: to avoid degradation due to overgrazing, livestock pressure should be limited in years with a spring drought, regardless of summer precipitation, especially in mesic grasslands. © 2016 International Association for Vegetation Scienc