La vegetazione del Parco Regionale Marturanum (Lazio settentrionale, Italia entrale): lineamenti fitosociologici e genesi del paesaggio vegetale

The Marturanum Regional Park is a small protected area (1,240 hectares), however it is placed along the interface between two of the main lithological units of Lazio, hence featuring a high diversity of flora, vegetation and landscape. Further, it includes a small part of theMonti dellaTolfa, a 30,000 hectares hilly rangewhich features an exceptionally low population density. The Tolfa hills are a biodiversity hotspot of C-Italy and show a very distinctive landscape pattern. The present paper outlines a phytosociological classification and syntaxonomical discussion of the numerous plant communities found in theMarturanumPark.The presentwork describes also the different role of the natural constraints and of the historical and cultural processes that have led to the peculiar landscape patterns nowadays found in the area, and in particular to the differentiation between the two landscape systems of the pyroclastic flow and the Tolfa flysch.Parco regionale Marturanu

The dry grasslands of Abruzzo National Park, the oldest protected area in the Apennines (Central Italy): overview of vegetation composition, syntaxonomy, ecology and diversity

The Abruzzo, Lazio and Molise National Park was established in 1923 and is considered a flagship conservation area in Italy. It includes large extensions of semi-natural grasslands, maintained by traditional transhumant grazing for centuries. The patterns and drivers of grassland composition within the Park are still poorly investigated, and the scattered phytosociological data available were often based on relevés with varied and not precisely defined sizes. In order to provide for the first time a general overview of the Park’s dry grasslands, we analysed a dataset of 87 relevés with a fixed size of 2 × 2 m, precisely delimited in the field and GPS-located. Specific research aims were: (1) to classify the vegetation plots into floristic-ecological types, supported by an analysis of mean (Italy-specific) Ellenberg Indicator Values (EIVs); (2) to assign the types to up-to-date phytosociological syntaxa; (3) to identify the main environmental drivers for both composition and richness patterns; (4) to test the degree of correlation between (Italy-specific) EIVs and the measured environmental variables. Environmental predictors included high-resolution climatologies and remote-sensed standing biomass. Main vegetation types were identified using Hierarchical Cluster Analysis (HCA). Distancebased RDA was performed as a constrained ordination method to reveal correlations between floristic composition and environmental variables. Drivers of species richness were explored through partial correlation and Regression Trees. HCA and NMDS revealed four floristically and ecologically well-interpretable groups, in turn well corresponding to the level of phytosociological class (namely Molinio-Arrhenatheretea, Nardetea strictae, Festuco hystricis-Ononidetea striatae and Festuco-Brometea). Constrained ordination showed that most of the floristic variation was explained by biomass, annual precipitation (Pann) and mean annual temperature (Tm). Strong and significant positive correlations were found between biomass and EIV for Nitrogen (EIV-N), and between Tm and EIV for Temperature (EIV-T). Strong and significant negative correlations were found between Pann and EIV-T, EIV for Continentality (EIV-C) and EIV for soil Reaction (EIV-R). Species richness was positively correlated with slope inclination and negatively with elevation; richness was higher in sites with a high rock cover, and on limestone or clayey substrata than on siliceous ones. We conclude that in the study area: a) dry semi-natural grasslands are arranged at least into four distinguishable, high rank floristic-ecological groups; b) a mixture of climatic (especially precipitation) and edaphic (especially bedrock and soil reaction) gradients are the main drivers of such composition patterns; c) species richness is higher in sites more stressed by summer drought and/or nutrient scarcity; d) community-means of Italy’s specific EIVs are well correlated with environmental variables in grasslands, including a good correspondence between EIV-T and mean annual temperature

Environmental drivers and spatial scaling of species abundance distributions in Palaearctic grassland vegetation

[EN] Species abundance distributions (SADs) link species richness with species abundances and are an important tool in the quantitative analysis of ecological communities. Niche-based and sample-based SAD models predict different spatial scaling properties of SAD parameters. However, empirical research on SAD scaling properties is largely missing. Here we extracted percentage cover values of all occurring vascular plants as proxies of their abundance in 1725 10-m(2) plots from the GrassPlot database, covering 47 regional data sets of 19 different grasslands and other open vegetation types of the Palaearctic biogeographic realm. For each plot, we fitted the Weibull distribution, a model that is able to effectively mimic other distributions like the log-series and lognormal, to the species-log abundance rank order distribution. We calculated the skewness and kurtosis of the empirical distributions and linked these moments, along with the shape and scale parameters of the Weibull distribution, to plot climatic and soil characteristics. The Weibull distribution provided excellent fits to grassland plant communities and identified four basic types of communities characterized by different degrees of dominance. Shape and scale parameter values of local communities on poorer soils were largely in accordance with log-series distributions. Proportions of subdominant species tended to be lower than predicted by the standard lognormal SAD. Successive accumulation of plots of the same vegetation type yielded nonlinear spatial scaling of SAD moments and Weibull parameters. This scaling was largely independent of environmental correlates and geographic plot position. Our findings caution against simple generalizations about the mechanisms that generate SADs. We argue that in grasslands, lognormal-type SADs tend to prevail within a wider range of environmental conditions, including more extreme habitats such as arid environments. In contrast, log-series distributions are mainly restricted to comparatively species-rich communities on humid and fertile soils.We thank all vegetation scientists who carefully collected the plant diversity data and contributed them to GrassPlot. The Eurasian Dry Grassland Group (EDGG) and the International Association for Vegetation Science (IAVS) supported the EDGG field workshops, which generated a core part of the GrassPlot data. The Bavarian Research Alliance (via the BayIntAn scheme) and the Bayreuth Center of Ecology and Environmental Research (BayCEER) funded the initial GrassPlot workshop during which the database was established (grants to Jurgen Dengler). Werner Ulrich acknowledges support from the Polish National Science Centre (Grant 2017/27/B/NZ8/00316). Idoia Biurrun and Juan Antonio Campos were partly supported by the Basque Government (IT936-16). Goffredo Filibeck was partly supported by the MIUR initiative "Department of Excellence" (Law 232/2016) granted to DAFNE. Peter Torok was supported by the NKFIH K 119225 and K 137573 projects and the HAS Momentum Program during the manuscript preparation. Franz Essl appreciates funding by the Austrian Science Foundation FWF (Grant I 3757-B29)

GrassPlot : the database of multi-scale plant diversity in Palaearctic grasslands

Understanding patterns and drivers of phytodiversity as well as ecological scaling laws and assembly rules constitute core interests both of vegetation ecologists and macroecologists. To enhance our understanding of these issues, we compiled the new “Database of Scale-Dependent Phytodiversity Patterns in Palaearctic Grasslands” (GrassPlot; GIVD ID EU-00-003) within the framework of the Eurasian Dry Grassland Group (EDGG). GrassPlot contains high-quality plot observations (relevés) of eight standard grain sizes (0.0001; 0.001 … 1000 m²) as well as nested-plot series with at least four different grain sizes. The scope of GrassPlot are the grasslands as well as other herb- or cryptogam-dominated terrestrial and semi-terrestrial vegetation types from the whole Palaearctic biogeographic realm (Europe, North Africa, West, Central and North Asia)

Biodiversity patterns of dry grasslands in the Central Apennines (Italy) along a precipitation gradient : experiences from the 10th EDGG Field Workshop

The 10th EDGG Field Workshop took place in a sector of the Central Apennine Mountains, Italy, in June 2017. Altogether, 22 researchers from nine European and Asian countries attended this Field Workshop. We sampled plant and insect biodiversity in submontane and lower-montane grasslands along a precipitation gradient, from the L’Aquila valley and the Fucino basin to the “Abruzzo, Lazio & Molise” National Park. The standardized EDGG sampling protocol, involving nested-plot series and additional 10-m2 relevés, was used. In the course of seven days of intensive fieldwork, we sampled 20 biodiversity plots along with 57 additional normal plots (yielding a total dataset of 97 10-m2 plots). Methodological additions tested in this workshop included the assessment of observer-related error (around 12% of the 10-m2 plots was resurveyed by a different team). In all plots, vascular plants, bryophytes and lichens were sampled. At each nested-plot series, also insects (Auchenorrhyncha) were sampled by local specialists, who developed an ad-hoc sampling procedure

GrassPlot v. 2.00 – first update on the database of multi-scale plant diversity in Palaearctic grasslands

Abstract: GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). Following a previous Long Database Report (Dengler et al. 2018, Phyto- coenologia 48, 331–347), we provide here the first update on content and functionality of GrassPlot. The current version (GrassPlot v. 2.00) contains a total of 190,673 plots of different grain sizes across 28,171 independent plots, with 4,654 nested-plot series including at least four grain sizes. The database has improved its content as well as its functionality, including addition and harmonization of header data (land use, information on nestedness, structure and ecology) and preparation of species composition data. Currently, GrassPlot data are intensively used for broad-scale analyses of different aspects of alpha and beta diversity in grassland ecosystems

Species-area relationships in continuous vegetation : evidence from Palaearctic grasslands

Aim Species–area relationships (SARs) are fundamental scaling laws in ecology although their shape is still disputed. At larger areas, power laws best represent SARs. Yet, it remains unclear whether SARs follow other shapes at finer spatial grains in continuous vegetation. We asked which function describes SARs best at small grains and explored how sampling methodology or the environment influence SAR shape. Location Palaearctic grasslands and other non‐forested habitats. Taxa Vascular plants, bryophytes and lichens. Methods We used the GrassPlot database, containing standardized vegetation‐plot data from vascular plants, bryophytes and lichens spanning a wide range of grassland types throughout the Palaearctic and including 2,057 nested‐plot series with at least seven grain sizes ranging from 1 cm2 to 1,024 m2. Using nonlinear regression, we assessed the appropriateness of different SAR functions (power, power quadratic, power breakpoint, logarithmic, Michaelis–Menten). Based on AICc, we tested whether the ranking of functions differed among taxonomic groups, methodological settings, biomes or vegetation types. Results The power function was the most suitable function across the studied taxonomic groups. The superiority of this function increased from lichens to bryophytes to vascular plants to all three taxonomic groups together. The sampling method was highly influential as rooted presence sampling decreased the performance of the power function. By contrast, biome and vegetation type had practically no influence on the superiority of the power law. Main conclusions We conclude that SARs of sessile organisms at smaller spatial grains are best approximated by a power function. This coincides with several other comprehensive studies of SARs at different grain sizes and for different taxa, thus supporting the general appropriateness of the power function for modelling species diversity over a wide range of grain sizes. The poor performance of the Michaelis–Menten function demonstrates that richness within plant communities generally does not approach any saturation, thus calling into question the concept of minimal area.publishedVersio