The leaf economic and plant size spectra of European forest understory vegetation

Forest understories play a vital role in ecosystem functioning and the provision of ecosystem services. However, the extent to which environmental conditions drive dominant ecological strategies in forest understories at the continental scale remains understudied. Here, we used similar to 29 500 forest vegetation plots sampled across Europe and classified into 25 forest types to explore the relative role of macroclimate, soil pH and tree canopy cover in driving abundance-weighted patterns in the leaf economic spectrum (LES) and plant size spectrum (PSS) of forest understories (shrub and herb layers). We calculated LES using specific leaf area (SLA) and leaf dry matter content (LDMC) and PSS using plant height and seed mass of vascular plant species found in the understories. We found that forest understories had more conservative leaf economics in areas with more extreme mean annual temperatures (mainly Fennoscandia and the Mediterranean Basin), more extreme soil pH and under more open canopies. Warm and summer-dry regions around the Mediterranean Basin and areas of Atlantic Europe also had taller understories with heavier seeds than continental temperate or boreal areas. Understories of broadleaved deciduous forests, such as Fagus forests on non-acid soils, or ravine forests, more commonly hosted species with acquisitive leaf economics. In contrast, some coniferous forests, such as Pinus, Larbc and Picea mire forests, or Pinus sylvestris light taiga and sclerophyllous forests, more commonly hosted species with conservative leaf economics. Our findings highlight the importance of macroclimate and soil factors in driving trait variation of understory communities at the continental scale and the mediator effect of canopy cover on these relationships. We also provide the first maps and analyses of LES and PSS of forest understories across Europe and give evidence that the understories of European forest types are differently positioned along major axes of trait variation

Disturbance indicator values for European plants

Motivation Indicator values are numerical values used to characterize the ecological niches of species and to estimate their occurrence along gradients. Indicator values on climatic and edaphic niches of plant species have received considerable attention in ecological research, whereas data on the optimal positioning of species along disturbance gradients are less developed. Here, we present a new data set of disturbance indicator values identifying optima along gradients of natural and anthropogenic disturbance for 6382 vascular plant species based on the analysis of 736,366 European vegetation plots and using expert-based characterization of disturbance regimes in 236 habitat types. The indicator values presented here are crucial for integrating disturbance niche optima into large-scale vegetation analyses and macroecological studies. Main types of variables contained We set up five main continuous indicator values for European vascular plants: disturbance severity, disturbance frequency, mowing frequency, grazing pressure and soil disturbance. The first two indicators are provided separately for the whole community and for the herb layer. We calculated the values as the average of expert-based estimates of disturbance values in all habitat types where a species occurs, weighted by the number of plots in which the species occurs within a given habitat type. Spatial location and grain Europe. Vegetation plots ranging in size from 1 to 1000 m(2). Time period and grain Vegetation plots mostly sampled between 1956 and 2013 (= 5th and 95th quantiles of the sampling year, respectively). Major taxa and level of measurement Species-level indicator values for vascular plants. Software format csv file

Ellenberg-type indicator values for European vascular plant species

Aims: Ellenberg-type indicator values are expert-based rankings of plant species according to their ecological optima on main environmental gradients. Here we extend the indicator-value system proposed by Heinz Ellenberg and co-authors for Central Europe by incorporating other systems of Ellenberg-type indicator values (i.e., those using scales compatible with Ellenberg values) developed for other European regions. Our aim is to create a harmonized data set of Ellenberg-type indicator values applicable at the European scale. Methods: We collected European data sets of indicator values for vascular plants and selected 13 data sets that used the nine-, ten- or twelve-degree scales defined by Ellenberg for light, temperature, moisture, reaction, nutrients and salinity. We compared these values with the original Ellenberg values and used those that showed consistent trends in regression slope and coefficient of determination. We calculated the average value for each combination of species and indicator values from these data sets. Based on species’ co-occurrences in European vegetation plots, we also calculated new values for species that were not assigned an indicator value. Results: We provide a new data set of Ellenberg-type indicator values for 8908 European vascular plant species (8168 for light, 7400 for temperature, 8030 for moisture, 7282 for reaction, 7193 for nutrients, and 7507 for salinity), of which 398 species have been newly assigned to at least one indicator value. Conclusions: The newly introduced indicator values are compatible with the original Ellenberg values. They can be used for large-scale studies of the European flora and vegetation or for gap-filling in regional data sets. The European indicator values and the original and taxonomically harmonized regional data sets of Ellenberg-type indicator values are available in the Supporting Information and the Zenodo repository

Morphological and molecular differentiation of the Croatian populations of Quercus pubescens Willd. [Fagaceae]

Taxonomy of the genus Quercus L. is very complicated and often controversial because of its great variability and intense gene flow among the related species. The purpose of this research was to determine morphological and molecular variation, relationships and taxonomic status of the Croatian populations of Quercus pubescens Willd. using morphological analysis of the leaves and RAPD-PCR technique. The results of the morphological and molecular analyses were very similar, both showing differentiation of the southern (Mediterranean) from the northern (Continental) pubescent oak populations. These two groups were clearly separated and the estimated gene flow among the populations that belong to different groups (Nm=1.38) is significantly less than among the populations that belong to the same group (Nm=3.70). The obtained results were compared to the available studies. This study confirms a high variability of the Q. pubescens populations, but differences were not so big to confirm the opinion of existence of several species in this area. The conclusion is that the southern Croatian populations could be pure Q. pubescens populations, while the peculiarities of the northern Croatian populations originate probably from the Q. petraea introgression

Effects of abandonment on the functional composition and forage nutritive value of a North Adriatic dry grassland community (Cicarija, Croatia)

Carici humilis-Centaureetum rupestris association is one of the most widespread types of pasture in Istria and of great environmental and economic interest. The research aims were to test if forage quantity, nutritive value and functional composition (grasses and grass-like, legumes, and forbs percentage) of these pastures change significantly in relation to: time of the growing season, management type (low use intensity grazing/grazing abandonment) and topographic variables. During 2008, phytomass samples were collected in grazed and ungrazed pastures of Cicarija (Croatia), in May, June, and September. Their composition in dry matter, ash, crude protein (CP), neutral and acid detergent fiber (NDF, ADF), acid detergent lignin (ADL) and in-vitro dry matter digestibility (IVDMD) were determined and net energy for lactation (NEL) and yield NEL were calculated. These variables followed a double trend, linked to the phenological phases of grasslands and to a land use/topographic gradient. Yield, yield NEL, dry matter, NDF, ADF and ADL increased during the growing season, while CP, NEL and IVDMD decreased. Yield, yield NEL, grasses and forbs, ash, and IVDMD were tied to the ungrazed pastures spread on the slopes, while ADF, ADL and dry matter had stronger correlation with grazed grasslands spread on the flat lands

Thermophilous deciduous forests in Southeastern Europe

This paper deals with the numerical elaboration of the database of 1764 releves of thermophilous deciduous forests assigned by the authors to the order Quercetalia pubescentis in the northwestern part of Southeastern Europe. After elimination of releves which were dominated by mesophilous deciduous and coniferous tree species, the stratification of releves was carried out. The TWINSPAN classification revealed eight ecologically and phytogeographically interpretable groups. Additionally the analysis of Pignatti indicator values passively projected on the PCA diagram of the eight groups, and a chorological analysis of individual groups were made. The analyses revealed that all groups in general match with the traditionally accepted alliances, such as Quercion pubescenti-sessiliflorae, Aceri tatarici-Quercion, Quercion confertae, Quercion petraeae-cerris, Syringo-Carpinion, Pruno tenelle-Syrinion, Carpinion orientalis and Fraxino orni-Ostryion. Finally, a synsystematic classification of the elaborated group is proposed, and the nomenclature is harmonised with the International Code of Phytosociological Nomenclature. The results are also presented in a synoptic table together with calculation of the diagnostic species.Slovenian Research Agenc

Thermophilous deciduous forests in Southeastern Europe

This paper deals with the numerical elaboration of the database of 1764 releves of thermophilous deciduous forests assigned by the authors to the order Quercetalia pubescentis in the northwestern part of Southeastern Europe. After elimination of releves which were dominated by mesophilous deciduous and coniferous tree species, the stratification of releves was carried out. The TWINSPAN classification revealed eight ecologically and phytogeographically interpretable groups. Additionally the analysis of Pignatti indicator values passively projected on the PCA diagram of the eight groups, and a chorological analysis of individual groups were made. The analyses revealed that all groups in general match with the traditionally accepted alliances, such as Quercion pubescenti-sessiliflorae, Aceri tatarici-Quercion, Quercion confertae, Quercion petraeae-cerris, Syringo-Carpinion, Pruno tenelle-Syrinion, Carpinion orientalis and Fraxino orni-Ostryion. Finally, a synsystematic classification of the elaborated group is proposed, and the nomenclature is harmonised with the International Code of Phytosociological Nomenclature. The results are also presented in a synoptic table together with calculation of the diagnostic species.Slovenian Research Agenc

Phylogenetic structure of European forest vegetation

Aims: (a) To determine the contribution of current macro-environmental factors in explaining the phylogenetic structure of European forest vegetation, (b) to map and describe spatial patterns in their phylogenetic structure and (c) to examine which lineages are the most important contributors to phylogenetic clustering and whether their contribution varies across forest types and regions. Location: Europe. Taxon: Angiosperms. Methods: We analysed the phylogenetic structure of 61,816 georeferenced forest vegetation plots across Europe considering alternative metrics either sensitive to basal (ancient evolutionary dynamics) or terminal (recent dynamics) branching in the phylogeny. We used boosted regression trees to model metrics of the phylogenetic structure as a function of current macro-environmental factors. We also identified clades encompassing significantly more taxa than under random expectation in phylogenetically clustered plots. Results: Phylogenetic clustering was driven by climatic stress and instability and was strong in the areas glaciated during the Pleistocene, likely reflecting limited postglacial migration, and to a lower extent in areas of northern-central Europe and in summer-dry Mediterranean regions. Phylogenetic overdispersion was frequent in the hemiboreal zone in Russia, in some areas around the Mediterranean Basin, and along the Atlantic seaboard of the Iberian Peninsula. The families Ericaceae, Poaceae and Fagaceae were overrepresented in clustered plots in different regions of Europe. Main conclusions: We provide the first maps and analyses on the phylogenetic structure of European forest vegetation at the plot level. Our results highlight the role of environmental filtering, postglacial dispersal limitation and spatial transitions between major biomes in determining the distribution of plant lineages in Europe

Classification of the Mediterranean lowland to submontane pine forest vegetation

Aim: Vegetation types of Mediterranean thermophilous pine forests dominated by Pinus brutia, Pinus halepensis, Pinus pinaster and Pinus pinea were studied in various areas. However, a comprehensive formal vegetation classification of these forests based on a detailed data analysis has never been developed. Our aim is to provide the first broad-scale classification of these pine forests based on a large data set of vegetation plots. Location: Southern Europe, North Africa, Levant, Anatolia, Crimea and the Caucasus. Methods: We prepared a data set of European and Mediterranean pine forest vegetation plots. We selected 7,277 plots dominated by the cold-sensitive Mediterranean pine species Pinus brutia, Pinus halepensis, Pinus pinaster and Pinus pinea. We classified these plots using TWINSPAN, interpreted the ecologically and biogeographically homogeneous TWINSPAN clusters as alliances, and developed an expert system for automatic vegetation classification at the class, order and alliance levels. Results: We described Pinetea halepensis as a new class for the Mediterranean lowland to submontane pine forests, included in the existing Pinetalia halepensis order, and distinguished 12 alliances of native thermophilous pine forests, including four newly described and three informal groups merging supposedly native stands and old-established plantations. The main gradients in species composition reflect elevational vegetation belts and the west–east, and partly north–south, biogeographical differences. Both temperature and precipitation seasonality co-vary with these gradients. Conclusions: We provide the first formal classification at the order and alliance levels for all the Mediterranean thermophilous pine forests based on vegetation-plot data. This classification includes traditional syntaxa, which have been critically revised, and a new class and four new alliances. We also outline a methodological workflow that might be useful for other vegetation classification syntheses. The expert system, which is jointly based on pine dominance and species composition, is a tool for applying this classification in research and nature conservation survey, monitoring and management

European Vegetation Archive: now EVA really starts!

European Vegetation Archive (EVA) was announced as a new initiative of the European Vegetation Survey at the EVS Meeting in Vienna in 2012. The aim of EVA is to create a centralized database of European vegetation plots by storing copies of national and regional databases on a single software platform using a unified taxonomic reference database. EVA does not affect the ongoing independent developments of source data­ bases and it guarantees that data property rights of the original contributors are re­ spected. EVA Data Property and Governance Rules were approved and the EVA website (www.euroveg.org/eva­database) was established in 2012. Since then several European vegetation­plot databases joined EVA. In the framework of the parallel Braun­Blanquet project, we obtained experience with handling multiple databases based on different taxonomies, and a prototype of Turboveg 3 was developed as a software tool for joint management of multiple databases. This prototype has recently been accepted as the platform for technical management of EVA according to the approved Rules. A spe­ cific challenge for EVA is joining multiple species lists with different taxonomies used in national and regional databases. To solve this issue, EVA took over the SynBioSys Taxon Database, developed earlier for the SynBioSys Europe project, which is a system of taxon names and concepts used in the individual databases and their matches to a unified list of European flora. This taxon database is currently being extended to ac­ count for new vegetation­plot databases and revised by taxonomic experts working in a newly established EVA Taxonomic Advisory Board. These technical developments made it possible that after two years since its formal establishment, first data sets could be uploaded to EVA, forming a basis for large­scale analyses of European vegeta­ tion diversity for both scientific purposes and applications