European Vegetation Research Articles

GrassPlot – a database of multi-scale plant diversity in Palaearctic grasslands

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). GrassPlot collects plot records (releves) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001;... 1,000 m(2)) and on nested-plot series with at least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes and 2,800 nested-plot series. The key components are richness data and metadata. However, most included datasets also encompass compositional data. About 14,000 plots have near-complete records of terricolous bryophytes and lichens in addition to vascular plants. At present, GrassPlot contains data from 36 countries throughout the Palaearctic, spread across elevational gradients and major grassland types. GrassPlot with its multi-scale and multi-taxon focus complements the larger international vegetationplot databases, such as the European Vegetation Archive (EVA) and the global database sPlot. Its main aim is to facilitate studies on the scale-and taxon-dependency of biodiversity patterns and drivers along macroecological gradients. GrassPlot is a dynamic database and will expand through new data collection coordinated by the elected Governing Board. We invite researchers with suitable data to join GrassPlot. Researchers with project ideas addressable with GrassPlot data are welcome to submit proposals to the Governing Board.

Large but decreasing effect of ozone on the European carbon sink

Abstract. The capacity of the terrestrial biosphere to sequester carbon and mitigate climate change is governed by the ability of vegetation to remove emissions of CO2 through photosynthesis. Tropospheric O3, a globally abundant and potent greenhouse gas, is, however, known to damage plants, causing reductions in primary productivity. Despite emission control policies across Europe, background concentrations of tropospheric O3 have risen significantly over the last decades due to hemispheric-scale increases in O3 and its precursors. Therefore, plants are exposed to increasing background concentrations, at levels currently causing chronic damage. Studying the impact of O3 on European vegetation at the regional scale is important for gaining greater understanding of the impact of O3 on the land carbon sink at large spatial scales. In this work we take a regional approach and update the JULES land surface model using new measurements specifically for European vegetation. Given the importance of stomatal conductance in determining the flux of O3 into plants, we implement an alternative stomatal closure parameterisation and account for diurnal variations in O3 concentration in our simulations. We conduct our analysis specifically for the European region to quantify the impact of the interactive effects of tropospheric O3 and CO2 on gross primary productivity (GPP) and land carbon storage across Europe. A factorial set of model experiments showed that tropospheric O3 can suppress terrestrial carbon uptake across Europe over the period 1901 to 2050. By 2050, simulated GPP was reduced by 4 to 9 % due to plant O3 damage and land carbon storage was reduced by 3 to 7 %. The combined physiological effects of elevated future CO2 (acting to reduce stomatal opening) and reductions in O3 concentrations resulted in reduced O3 damage in the future. This alleviation of O3 damage by CO2-induced stomatal closure was around 1 to 2 % for both land carbon and GPP, depending on plant sensitivity to O3. Reduced land carbon storage resulted from diminished soil carbon stocks consistent with the reduction in GPP. Regional variations are identified with larger impacts shown for temperate Europe (GPP reduced by 10 to 20 %) compared to boreal regions (GPP reduced by 2 to 8 %). These results highlight that O3 damage needs to be considered when predicting GPP and land carbon, and that the effects of O3 on plant physiology need to be considered in regional land carbon cycle assessments.

The first Pleistocene fossil records of Urtica kioviensis Rogow. (Urticaceae) and Potamogeton sukaczevii Wieliczk. (Potamogetonaceae) in the British Isles

Seeds of the extant Urtica kioviensis Rogow. (Urticaceae) and endocarps of the extinct Potamogeton sukaczevii Wieliczk. (Potamogetonaceae) were recorded in diverse plant macrofossil assemblages recovered from organic sediments exposed during excavations at Saham Toney, Norfolk, UK. Aminostratigraphical data show the sediments were deposited during the Ipswichian (Last Interglacial) Stage. Palynological data indicates deposition during the Carpinus pollen zone of the Ipswichian Stage—the latter part of pollen zone Ip IIb and Ip III. The records are noteworthy not only because they are the first in the British Pleistocene but also because of the geographical occurrences of these two species. Urtica kioviensis is absent from the British flora today and has a modern range in central and eastern Europe (only extending as far west as north–east Germany and Denmark), while the extinct Potamogeton sukaczevii has only been recovered from Late Pleistocene sediments in Belarus, Lithuania, Poland and western Russia. The presence of U. kioviensis along with other exotic species to the British Isles (e.g. Najas minor L. and Salvinia natans L., which today have central and southern ranges in Europe and in the case of S. natans occurs on other continents) may point to more continental conditions or warmer summer conditions during the second half of the Ipswichian Stage in southern Britain. No modern analogues occur in Britain for the assemblages recovered from Saham Toney. Evidence of colder winters or at least warmer summers at the time of deposition does not support the view that sea-level peaked in the Carpinus zone of the Eemian Stage (correlated with the Ipswichian Stage) associated with increased oceanicity. Southern Britain would have been under the influence of the Atlantic Ocean and a degree of oceanicity is supported by the presence of two thermophilous taxa, Hedera and Ilex, in the pollen spectra from Saham Toney. Alternative explanations for the presence of these exotic species are that they were tolerating mild winters and cooler summers at the time of deposition or exploiting suitable micro-environments. The distribution of P. sukaczevii is probably an artefact of the distribution of expertise in the identification of Potamogeton fossil endocarps rather than having any palaeogeographic or palaeoclimatic significance. It is an extinct ancestor of the extant P. maackianus A. Benn, an eastern Asian pondweed. Its discovery in Britain encourages a reassessment of plant macrofossil assemblages from western Europe, which may lead to a consideration of the relationship between the Late Pleistocene vegetation of Europe and eastern Asia.

Introduction: Vegetation science and the habitats directive: approaches and methodologies of a never-ending story

Rendiconti Lincei has dedicated a Special Issue to present a number of case studies highlighting the role played by the European Vegetation Survey Working Group established by Sandro Pignatti and his colleagues in support to the implementation of the Habitats Directive. Studies include theoretical analyses as well as researches conducted at different spatial and temporal scales focused on the assessment and monitoring of the conservation status of habitats and target plant species, identification of new habitats and subtypes, and their diagnostic species.

Classification of European and Mediterranean coastal dune vegetation

AbstractAimsAlthough many phytosociological studies have provided detailed local and regional descriptions of coastal dune vegetation, a unified classification of this vegetation in Europe and the Mediterranean Basin has been missing. Our aim is to produce a formalized classification of this vegetation and to identify the main factors driving its plant species composition at a continental scale.LocationAtlantic and Baltic coasts of Europe, Mediterranean Basin and the Black Sea region.MethodsWe compiled a database of 30,759 plots of coastal vegetation, which were resampled to reduce unbalanced sampling effort, obtaining a data set of 11,769 plots. We classified these plots with TWINSPAN, interpreted the resulting clusters and used them for developing formal definitions of phytosociological alliances of coastal dune vegetation, which were included in an expert system for automatic vegetation classification. We related the alliances to climatic factors and described their biogeographic features and their position in the coastal vegetation zonation. We examined and visualized the floristic relationships among these alliances by means of DCA ordination.ResultsWe defined 18 alliances of coastal dune vegetation, including the newly described Centaureo cuneifoliae‐Verbascion pinnatifidi from the Aegean region. The main factors underlying the differentiation of these alliances were biogeographic and macroclimatic contrasts between the Atlantic–Baltic, Mediterranean and Black Sea regions, along with ecological differences between shifting and stable dunes. The main difference in species composition was between the Atlantic–Baltic and Mediterranean–Black Sea regions. Within the former region, the main difference was driven by the different ecological conditions between shifting and stable dunes, whereas within the latter, the main difference was biogeographic between the Mediterranean and the Black Sea.ConclusionsThe first formal classification of the European coastal dune vegetation was established, accompanied by an expert system containing the formal definitions of alliances, which can be applied to new data sets. The new classification system critically revised the previous concepts and integrated them into a consistent framework, which reflects the main gradients in species composition driven by biogeographic influences, macroclimate and the position of the sites in the coast–inland zonation of the dune systems. A revision of the class concept used in EuroVegChecklist is also proposed.

Circumpolar Arctic Vegetation Classification

Aims: An Arctic Vegetation Classification (AVC) is needed to address issues related to rapid Arctic-wide changes to climate, land-use, and biodiversity. Location: The 7.1 million km2 Arctic tundra biome. Approach and conclusions: The purpose, scope and conceptual framework for an Arctic Vegetation Archive (AVA) and Classification (AVC) were developed during numerous workshops starting in 1992. The AVA and AVC are modeled after the European vegetation archive (EVA) and classification (EVC). The AVA will use Turboveg for data management. The AVC will use a Braun-Blanquet (Br.-Bl.) classification approach. There are approximately 31,000 Arctic plots that could be included in the AVA. An Alaska AVA (AVA-AK, 24 datasets, 3026 plots) is a prototype for archives in other parts of the Arctic. The plan is to eventually merge data from other regions of the Arctic into a single Turboveg v3 database. We present the pros and cons of using the Br.-Bl. classification approach compared to the EcoVeg (US) and Biogeoclimatic Ecological Classification (Canada) approaches. The main advantages are that the Br.-Bl. approach already has been widely used in all regions of the Arctic, and many described, well-accepted vegetation classes have a pan-Arctic distribution. A crosswalk comparison of Dryas octopetala communities described according to the EcoVeg and the Braun-Blanquet approaches indicates that the non-parallel hierarchies of the two approaches make crosswalks difficult above the plantcommunity level. A preliminary Arctic prodromus contains a list of typical Arctic habitat types with associated described syntaxa from Europe, Greenland, western North America, and Alaska. Numerical clustering methods are used to provide an overview of the variability of habitat types across the range of datasets and to determine their relationship to previously described Braun-Blanquet syntaxa. We emphasize the need for continued maintenance of the Pan-Arctic Species List, and additional plot data to fully sample the variability across bioclimatic subzones, phytogeographic regions, and habitats in the Arctic. This will require standardized methods of plot-data collection, inclusion of physiogonomic information in the numeric analysis approaches to create formal definitions for vegetation units, and new methods of data sharing between the AVA and national vegetation- plot databases.

Calcareous grassland restoration at a coarse quarry waste dump in the Italian Alps

Establishing semi-natural grasslands by using seeds from wild harvesting is an effective method to restore vegetation with high natural value. However, studies implementing this strategy for the revegetation of coarse soils are scarce. In this study, different types of propagation material (green hay, dry hay, and hay-flower from seed stripping) harvested at a species-rich European vegetation typical for calcareous soils (Mesobromion) were used at different sowing densities (range, 450–3000 seeds per m2) to restore a very unfertile soil consisting of coarse wastes from a calcareous quarry. The experiment, organised in a randomised block design with three replicates, was established in 2009, and the species composition and structure were surveyed over five years. The threshold of 70% vegetation cover effective against erosion was achieved within two years after sowing. Neither the type of propagation material nor the sowing density influenced the number of species transferred or the final vegetation cover. However, seed density affected the time of achieving the 70% threshold of plant cover important for erosion control (two or three years after sowing depending on the seed density). Of the seventy-three donor site species, fifty-nine were recorded at least during one year on the restored site (absolute transfer rate of 81%), but only forty-six were recorded in the last year (final transfer rate of 63%). Vegetation development was characterised by loss or decrease of donor site species not well adapted to grow in nutrient-poor soils and increase by species typical for coarse textured soils. The very low soil nitrogen content caused an abundance of nitrogen-fixing species (legumes) compared with that at the donor site. Restoring very coarse calcareous quarry wastes, even without soil improvement, is possible provided the climatic conditions are favourable and seeds of good quality are available.

What are the organismic elements of vegetation science?

AbstractThe recent inclusion of communities of planktonic algae and microbial crusts into the system of European vegetation types is critically discussed. It is argued that formal vegetation classification should be limited to plant taxa represented by macroscopic individuals within a plot, including all vascular plants, bryophytes, lichens, charophyta and macrophytic chlorophyta, rhodophyta or phaeophyta. In the interest of comparability and methodological stringency, all microscopic algae and all prokaryotes, including cyanobacteria, and the habitats dominated by such microorganisms (e.g. plankton, biofilms and crusts), should be excluded from vegetation classification.

EU priority habitats: rethinking Mediterranean coastal pine forests

EU habitats knowledge is essential to better protect nature and to yield well-aimed management decisions. In this study, we analysed a debated habitat influenced by past human planting activities. We compared the Pinus halepensis and the P. pinea forests, belonging to the priority EU habitat 2270*, by means of ecological features provided by the Ellenberg indicator values and diagnostic species selected from “Vegetation of Europe” classes and the “Italian Interpretation Manual of the Dir. 92/43/EEC”. We used 159 vegetation plots in the Italian Peninsula, covering a wide range of this habitat in Italy. We found consistent ecological dissimilarities between Pinus halepensis and P. pinea forests and different diagnostic species. Moreover, P. halepensis forests hosted more diagnostic species of foredune habitats. Finally, we suggest that diagnostic species are a good indicator for studying EU habitat types resemblance, and we highlight the importance of the EU habitat 2270* in Italy, proposing two different subtypes.

The Romanian Grassland Database (RGD): historical background, current status and future perspectives

This report describes the Romanian Grassland Database (RGD), registered under EU-RO-008 in the Global Index of Vegetation-Plot Databases (GIVD). This collaborative initiative aims to collect all available vegetation-plot data (releves) of grasslands and other open habitats from the territory of Romania to provide them for science, nationally and internationally, e.g. via the European Vegetation Archive (EVA) and the global database sPlot. The database mainly contains vegetation-plots from not only wet, mesic, dry, saline, alpine and rocky grasslands, but also other vegetation types like heathlands, mires, ruderal, segetal, aquatic and cryptogamdominated vegetation. Currently, 21,685 releves have mainly been digitised from literature sources (90%), while the remainder comes from individual unpublished sources (10%). We report on the background and history of the RGD, explain its Data Property and Governance Rules under which data are contributed and retrieved, and outline how the RGD can contribute to research in the fields of vegetation ecology, macroecology and conservation.

High-diversity European palaeoflora favoured by early Pliocene warmth: New chronological constraints from the Ca′ Viettone section, NW Italy

We present new chronological constraints for a reference European palaeoflora based on integrated stratigraphic, palaeobotanical, palaeomagnetic and micropalaeontological analysis carried out on the Pliocene section of Ca′ Viettone, northwestern Italy. This site is characterized by rich fossil plant records of high taxonomic diversity, good preservation, and varied taphonomic mode. Palaeofloral analysis shows that the Ca′ Viettone assemblage reflects a chronologically delimited and distinguishable stage of vegetation development in northern Italy (called Ca′ Viettone Florenkomplex). Palaeomagnetic analyses show a dominant normal polarity that, however, seems to be the result of a remagnetization process due to secondary oxidation. Layers with no evidence of oxidation have registered a reverse polarity, which likely represents the original magnetization of the sediments. These results, in combination with biochronological indications, suggest that deposition of the succession preceded the Gilbert-Gauss reversal and took place during the final part of the Gilbert chron. This confirms a late Zanclean age for the rich Ca′ Viettone palaeoflora and allows us to propose this locality both as reference for a regional Florenkomplex and as a representative example of terrestrial vegetation in Europe during the early Pliocene warm interval.

Синантропные сообщества с Dactylis glomerata L. в Курской области

The results of the studies of synanthropic vegetation in Kursk Region (area is 29 800 sq. km), that is located between 50°54′–52°26′ N and 34°05′–38°31′ E, are given. Zonal vegetation is represented by broad-leaved forests on dark-gray forest soils and meadow steppes on chernozems. Synanthropic vegetation was being studied since 2003. 58 relevés were performed in the city of Kursk and few district centers of Kursk Region. The data were treated by IBIS 7.2 software package (Zverev, 2007). Classification is carried out according to Braun-Blanquet approach, the names of the higher syntaxa follow to «Vegetation of Europe…» (Mucina et al., 2016). Ecological conditions, such as soil moisture, richness in mineral nitrogen, light were assessed with the use of average values by H. Ellenberg et al. (1992) ecological scales while hemero­biality with use of average values of N. G. Ilminskikh (1993) ecological scale and processed by IBIS software (Zverev, 2007). As a result, 2 new associations of synanthropic ve­getation were described. Their communities are widely distributed in anthropogenic habitats within the study area. Ass. Arrhenathero elatioris–Dactylidetum glomeratae (Arepieva 2015) ass. nov. et stat. nov. hoc loco (Table 2, relevés 1–35; nomenclature type (holo­typus) is relevé 19 in the paper by L. A. Arepieva (2015: 102, Table 34), it corresponds to relevé 4 ­(author’s number — 37) in Table 2 in this article) refers to the alliance Convolvulo arvensis–Agropyrion repentis Görs 1967, order Agropyretalia intermedio–repentis T. Müller et Görs 1969, class Artemisietea vulgaris Lohmeyer et al. in Tx. ex von Rochow 1951. Diagnostic species are Arrhenatherum elatius and Dactylis glomerata. Two variants are distinguished within the association. Communities of var. typica (Table 2, rele­vés 1–19; Fig. 1) are described on sunny sites. Communities of var. Glechoma hederacea (Table 2, relevés 20–35; Fig. 2) are often formed in partially shaded habitats under strong anthropogenic impact, that’s why species of the order Arctio lappae–Artemisietalia­ ­vulgaris Dengler 2002 and the class Sisymbrietea Gutte et Hilbig 1975 are more common there. Previously (Arepieva, 2015) we considered this association decribed in the Kursk city as subass. Convolvulo arvensis–Elytrigietum repentis Felföldy 1943 dactylidetosum glomeratae Arepieva 2015. Presently, its rank is rised up to the аssociation for the following reasons: this syntaxon has a wide area of distribution, as the studied communities are common throughout the region, and it good enough differs of the other syntaxa of the alliance Convolvulo arvensis–Agropyrion repentis that are known in our region. Synoptic table (Table 3), value ranges of ecological factors for аssociations (Fig. 3) and DCA-ordination diagram (Fig. 4) demonstrate the differentiation of the syntaxa. The differences of this аssociation of those close to it in composition known in other regions (ass. Convolvulo arvensis–Elytrigietum repentis in Czech Republic, ass. Agropyro repentis–Dactylidetum glomeratae Ubaldi 1976 em. Ubaldi, Puppi et Speranza 1983 in Italy, ass. Geranio tuberosae–Dactylidetum Korzh. et Kljukin 1990 in Ukraine) are discussed. Among syntaxa of the meadow vegetation the most similar in species composition to it is subass. Arrhenatheretum elatioris dactylidetosum glomeratae Nowiński 1967 (alliance Arrhenatherion elatioris Luquet 1926, order Arrhenatheretalia elatioris Tx. 1931, class Molinio-Arrhenatheretea Tx. 1937) in Poland. The syntaxon differentiations are shown in Table 4. In Kursk Region close to the described association is ass. Anthoxantho–Agrostietum tenuis Sillinger 1933 (alliance Cynosurion cristati Tx. 1947, order Arrhenatheretalia elatioris Tx. 1931, class Molinio-Arrhenatheretea Tx. 1937). Ass. Glechomo hederaceae–Dactylidetum glomeratae ass. nov. hoc loco (Table 2, relevés 36–58; nomenclature type (holotypus hoc loco) — relevé 41 (author’s number — 650); Fig. 5) belongs to the alliance Arction lappae Tx. 1937, order Arctio lappae–Artemisietalia vulgaris Dengler 2002, class Epilobietea angustifolii Tx. et Preising ex von Rochow 1951. Diagnostic species are Carex contigua, Dactylis glomerata, Elsholtzia ciliata, Glechoma hederacea, Xantho­xalis stricta. Its communities, that occur in parks and gardens, were described in shaded habitats. The differences between this association and those of synanthropic vegetation close to it in the species composition are shown: ass. Leonuro–Arctietum tomentosi Lohmeyer in Tx. 1950 in Kursk Region and ass. Arctio tomentosi–Rumicetum obtusifolii Passarge 1959 in Slovakia (Table 5; Fig. 6, 7). Identified syntaxa, described within different orders and classes, have high floristic similarity because their communities are directed series with gradually changing conditions (the DCA-ordination diagram on Fig. 8). There is a change of impact of some ecological factors (light, moisture, reaction and richness in mineral nitrogen of soils and substrates) along axis 1. On this axis the communities of var. Glechoma hederacea of the ass. Arrhenathero elatioris–Dactylidetum glomeratae occupy an intermediate position and species, that have high constancy in ass. Glechomo hederaceae–Dactylidetum glomeratae, also occur in these. In all likelihood, the axis 2 is a change in degree of anthropogenic impact, which does not significantly influence on the syntaxon differentiation. The results of DCA-ordination are confirmed by the value ranges of ecological factors (Fig. 9).

Chorological classification approach for species and ecosystem conservation practice

The habitat type allocation approach based on the EUNIS Habitat Classification and the JUICE version 7 software is used for the conservation of species and ecosystem biodiversity. Using the vegetation plots of the Vegetation Database of Tatarstan, included in the EVA (European Vegetation Archive) and GIVD (Global Index of Vegetation-plots Databases) types of habitats of dry meadows and steppes are distinguished by differing compositions of the leading families composing their flora – Asteraceae, Fabaceae, Poaceae and Rosaceae. E12a – Semi-dry perennial calcareous grassland, and E12b - Perennial calcareous grassland and basic steppes were identified. The selected group of relevés that do not correspond to any of the EUNIS types can be considered specific for ecotone forest-steppe landscapes of the southeast of the Republic of Tatarstan. In all types of studied habitats, rare and protected plant species are noted, most of which are South-East-European-Asian species.

Naturalization of European plants on other continents: The role of donor habitats

The success of European plant species as aliens worldwide is thought to reflect their association with human-disturbed environments. However, an explicit test including all human-made, seminatural and natural habitat types of Europe, and their contributions as donor habitats of naturalized species to the rest of the globe, has been missing. Here we combine two databases, the European Vegetation Checklist and the Global Naturalized Alien Flora, to assess how human influence in European habitats affects the probability of naturalization of their plant species on other continents. A total of 9,875 native European vascular plant species were assigned to 39 European habitat types; of these, 2,550 species have become naturalized somewhere in the world. Species that occur in both human-made habitats and seminatural or natural habitats in Europe have the highest probability of naturalization (64.7% and 64.5% of them have naturalized). Species associated only with human-made or seminatural habitats still have a significantly higher probability of becoming naturalized (41.7% and 28.6%, respectively) than species confined to natural habitats (19.4%). Species associated with arable land and human settlements were recorded as naturalized in the largest number of regions worldwide. Our findings highlight that plant species' association with native-range habitats disturbed by human activities, combined with broad habitat range, play an important role in shaping global patterns of plant invasions.

Pollen‐derived biomes in the Eastern Mediterranean–Black Sea–Caspian‐Corridor

AbstractAimTo evaluate the biomization technique for reconstructing past vegetation in the Eastern Mediterranean–Black Sea–Caspian‐Corridor using an extensive modern pollen data set and comparing reconstructions to potential vegetation and observed land cover data.LocationThe region between 28–48°N and 22–62°E.MethodsWe apply the biomization technique to 1,387 modern pollen samples, representing 1,107 entities, to reconstruct the distribution of 13 broad vegetation categories (biomes). We assess the results using estimates of potential natural vegetation from the European Vegetation Map and the Physico‐Geographic Atlas of the World. We test whether anthropogenic disturbance affects reconstruction quality using land use information from the Global Land Cover data set.ResultsThe biomization scheme successfully predicts the broadscale patterns of vegetation across the region, including changes with elevation. The technique discriminates deserts from shrublands, the prevalence of woodlands in moister lowland sites, and the presence of temperate and mixed forests at higher elevations. Quantitative assessment of the reconstructions is less satisfactory: the biome is predicted correctly at 44% of the sites in Europe and 33% of the sites overall. The low success rate is not a reflection of anthropogenic impacts: only 33% of the samples are correctly assigned after the removal of sites in anthropogenically altered environments. Open vegetation is less successfully predicted (33%) than forest types (73%), reflecting the under‐representation of herbaceous taxa in pollen assemblages and the impact of long‐distance pollen transport into open environments. Samples from small basins (<1 km2) are more likely to be reconstructed accurately, with 58% of the sites in Europe and 66% of all sites correctly predicted, probably because they sample an appropriate pollen source area to reflect regional vegetation patterns in relatively heterogeneous landscapes. While methodological biases exist, the low confidence of the quantitative comparisons should not be over‐emphasized because the target maps themselves are not accurate representations of vegetation patterns in this region.Main ConclusionsThe biomization scheme yields reasonable reconstructions of the broadscale vegetation patterns in the Eastern Mediterranean–Black Sea–Caspian‐Corridor, particularly if appropriate‐sized sampling sites are used. Our results indicate biomization could be used to reconstruct changing patterns of vegetation in response to past climate changes in this region.

Impacts of temperature extremes on European vegetation during the growing season

Abstract. Temperature is a key factor controlling plant growth and vitality in the temperate climates of the mid-latitudes like in vast parts of the European continent. Beyond the effect of average conditions, the timings and magnitudes of temperature extremes play a particularly crucial role, which needs to be better understood in the context of projected future rises in the frequency and/or intensity of such events. In this work, we employ event coincidence analysis (ECA) to quantify the likelihood of simultaneous occurrences of extremes in daytime land surface temperature anomalies (LSTAD) and the normalized difference vegetation index (NDVI). We perform this analysis for entire Europe based upon remote sensing data, differentiating between three periods corresponding to different stages of plant development during the growing season. In addition, we analyze the typical elevation and land cover type of the regions showing significantly large event coincidences rates to identify the most severely affected vegetation types. Our results reveal distinct spatio-temporal impact patterns in terms of extraordinarily large co-occurrence rates between several combinations of temperature and NDVI extremes. Croplands are among the most frequently affected land cover types, while elevation is found to have only a minor effect on the spatial distribution of corresponding extreme weather impacts. These findings provide important insights into the vulnerability of European terrestrial ecosystems to extreme temperature events and demonstrate how event-based statistics like ECA can provide a valuable perspective on environmental nexuses.

Alien plant invasions in European woodlands

AbstractAimWoodlands make up a third of European territory and carry out important ecosystem functions, yet a comprehensive overview of their invasion by alien plants has never been undertaken across this continent.LocationEurope.MethodsWe extracted data from 251,740 vegetation plots stored in the recently compiled European Vegetation Archive. After filtering (resulting in 83,396 plots; 39 regions; 1970–2015 time period), we analysed the species pool and frequency of alien vascular plants with respect to geographic origin and life‐forms, and the levels of invasion across the European Nature Information System (EUNIS) woodland habitats.ResultsWe found a total of 386 alien plant species (comprising 7% of all recorded vascular plants). Aliens originating from outside of and from within Europe were almost equally represented in the species pool (192 vs. 181 species) but relative frequency was skewed towards the former group (77% vs. 22%) due, to some extent, to the frequent occurrence of Impatiens parviflora (21% frequency among alien plants). Phanerophytes were the most species‐rich life‐form (148 species) and had the highest representation in terms of relative frequency (39%) among aliens in the dataset. Apart from Europe (181 species), North America was the most important source of alien plants (109 species). At the local scale, temperate and boreal softwood riparian woodland (5%) and mire and mountain coniferous woodland (<1%) had the highest and lowest mean relative alien species richness (percentage of alien species per plot), respectively.Main conclusionsOur results indicate that European woodlands are prone to alien plant invasions especially when exposed to disturbance, fragmentation, alien propagule pressure and high soil nutrient levels. Given the persistence of these factors in the landscape, competitive alien plant species with a broad niche, including alien trees and shrubs, are likely to persist and spread further into European woodlands.

Quantifying the effects of land use and climate on Holocene vegetation in Europe

Early agriculture can be detected in palaeovegetation records, but quantification of the relative importance of climate and land use in influencing regional vegetation composition since the onset of agriculture is a topic that is rarely addressed. We present a novel approach that combines pollen-based REVEALS estimates of plant cover with climate, anthropogenic land-cover and dynamic vegetation modelling results. This is used to quantify the relative impacts of land use and climate on Holocene vegetation at a sub-continental scale, i.e. northern and western Europe north of the Alps. We use redundancy analysis and variation partitioning to quantify the percentage of variation in vegetation composition explained by the climate and land-use variables, and Monte Carlo permutation tests to assess the statistical significance of each variable. We further use a similarity index to combine pollen-based REVEALS estimates with climate-driven dynamic vegetation modelling results. The overall results indicate that climate is the major driver of vegetation when the Holocene is considered as a whole and at the sub-continental scale, although land use is important regionally. Four critical phases of land-use effects on vegetation are identified. The first phase (from 7000 to 6500 BP) corresponds to the early impacts on vegetation of farming and Neolithic forest clearance and to the dominance of climate as a driver of vegetation change. During the second phase (from 4500 to 4000 BP), land use becomes a major control of vegetation. Climate is still the principal driver, although its influence decreases gradually. The third phase (from 2000 to 1500 BP) is characterised by the continued role of climate on vegetation as a consequence of late-Holocene climate shifts and specific climate events that influence vegetation as well as land use. The last phase (from 500 to 350 BP) shows an acceleration of vegetation changes, in particular during the last century, caused by new farming practices and forestry in response to population growth and industrialization. This is a unique signature of anthropogenic impact within the Holocene but European vegetation remains climatically sensitive and thus may continue to respond to ongoing climate change.

Validation of ozone response functions for annual Mediterranean pasture species using close-to-field-conditions experiments.

Ozone (O3) critical levels have been established under the Long-Range Transboundary Air Pollution Convention to assess the risk of O3 effects in European vegetation. A recent review study has led to the development of O3 critical levels for annual Mediterranean pasture species using plants growing in well-watered pots at a coastal site and under low levels of competition. However, uncertainties remain in the extrapolation of the O3 sensitivity of these species under natural conditions. The response of two O3-sensitive annual Mediterranean pasture Trifolium species at the coastal site was compared with the response of the same species growing at a continental site, in natural soil and subject to water-stress and inter-specific competition, representing more closely their natural habitat. The slopes of exposure- and dose-response relationships derived for the two sites showed differences in the response to O3 between sites attributed to differences in environmental growing conditions, growing medium and the level of inter-specific competition, but the effect of the individual factors could not be assessed separately. Dose-based O3 indices partially explained differences due to environmental growing conditions between sites. The slopes showed that plants were more sensitive to O3 at the continental site, but homogeneity of slopes tests revealed that results from both experimental sites may be combined. Although more experimental data considering complex inter-specific competition situations and the effect of important interactive factors such as nitrogen would be needed, these results confirm the validity of applying the current flux-based O3 critical level under close to natural growing conditions. The AOT40-based O3 critical level derived at the coastal site was also considered a suitable risk indicator in close to natural growing conditions in the absence of soil moisture limitations on plant growth.

Patterns and dynamics of European vegetation change over the last 15,000 years

AbstractAimPalaeoecological reconstructions document past vegetation change, with estimates of fast shifts in species distributions. The resulting rates of plant spread are often not matched by model simulations of climate‐driven vegetation dynamics. Genetic surveys of extant plant populations document directions of the post‐glacial spread of trees, challenging traditional interpretations. Our aim is to examine an updated continental pollen data set from Europe in the light of the new ideas about vegetation dynamics emerging from genetic research and vegetation modelling studies.LocationEurope.MethodsWe use pollen data from the European Pollen Database (EPD) to construct interpolated maps of pollen percentages documenting changes in the distribution and abundance of major plant genera and the grass family in Europe over the last 15,000 years.ResultsOur analyses confirm high rates of post‐glacial spread with at least 1000 m year−1 for Corylus, Ulmus and Alnus and average rates of 400 m year−1 for Tilia, Quercus, Fagus and Carpinus. The late Holocene expansions of Picea and Fagus populations in many European regions cannot be explained by migrational lag. Both taxa shift their population centres towards the Atlantic coast suggesting that climate may have played a role in the timing of their expansions. The slowest rates of spread were reconstructed for Abies.Main conclusionsThe calculated rates of post‐glacial plant spread are higher in Europe than those from North America, which may be due to more rapid shifts in climate mediated by the Gulf Stream and westerly winds. Late Holocene anthropogenic land use practices in Europe had major effects on individual taxa, which in combination with climate change contributed to shifts in areas of abundance and dominance. The high rates of spread calculated from the European pollen data are consistent with rapid tracking of early Holocene climate change by common tree species, documenting that plants can spread fast tracing their climate space, regardless of their dispersal strategy.