The European Vegetation Archive (EVA) is a centralized database of European vegetation plots developed by the IAVS Working Group European Vegetation Survey. It has been in development since 2012 and first made available for use in research projects in 2014. It stores copies of national and regional vegetation‐ plot databases on a single software platform. Data storage in EVA does not affect on‐going independent development of the contributing databases, which remain the property of the data contributors. EVA uses a prototype of the database management software TURBOVEG 3 developed for joint management of multiple databases that use different species lists. This is facilitated by the SynBioSys Taxon Database, a system of taxon names and concepts used in the individual European databases and their corresponding names on a unified list of European flora. TURBOVEG 3 also includes procedures for handling data requests, selections and provisions according to the approved EVA Data Property and Governance Rules. By 30 June 2015, 61 databases from all European regions have joined EVA, contributing in total 1 027 376 vegetation plots, 82% of them with geographic coordinates, from 57 countries. EVA provides a unique data source for large‐scale analyses of European vegetation diversity both for fundamental research and nature conservation applications. Updated information on EVA is available online at http://euroveg.org/eva-database.

European beech (Fagus sylvatica) is a drought-sensitive species that likely will retreat from its xeric distribution edges in the course of climate warming. Physiological measurements indicate that the species may not only be sensitive to soil water deficits, but also to high temperatures and elevated atmospheric vapor pressure deficits (vpd). Through microclimatological measurements in the stand interior across near-natural beech forest–oak forest ecotones, we searched for microclimatic tipping points in the contact zone with the aim to define the thermic and hydrometeorological limits of beech more precisely. In three transects in the foothills of the Romanian western Carpathians, we measured in mid-summer 2019 air temperature, relative air humidity, and vpd at 2 m height in the stand interior across the ecotone from pure oak to pure beech forests, and compared the readings to the microclimate in forest gaps. Mean daytime temperature (T) and vpd were by 2 K and 2 hPa, respectively, higher in the oak forests than the beech forests; the extremes differed even more. Especially in the second half of the day, the oak forests heated up and were more xeric than the beech forests. Part of the differences is explained by the elevation difference between oak and beech forests (200–300 m), but species differences in canopy structure, leaf area, and canopy transmissivity enhance the microclimatic contrast. Our T and vpd data point to thresholds at about 30 °C and 25 hPa as maxima tolerated by beech in the lowermost shade canopy for extended periods. In conclusion, the rather sharp stand microclimatic gradient demonstrated here for the xeric distribution limit of beech may well be the decisive factor that hinders the spread of beech into the warmer oak forests.

Climate change challenges important native timber species in Central Europe. The introduction of non-native tree species originating from warmer climates is one option to make Central European forests compatible to global warming. This, however, requires an assessment of the species’ growth requirements, and of its impact on biodiversity in its native ranges. Silver lime (Tilia tomentosa), a moderately drought-tolerant, thermophilous tree species of South-eastern Europe is considered suitable for the future. Along three elevational transects in western Romania, we assessed the impact of changing climate and local site conditions on the abundance of this tree species and contrasted plant species diversity and composition of lime-dominated forests with mesophytic oak and beech forests. Local site conditions and disturbance histories shaped the distribution pattern of silver lime. When dominant, it reduced plant species diversity within stands due to its dense canopy. For shade-tolerant, mesophytic species, though, lime forests provided an additional habitat and extended their range into warmer environments. Thus, silver lime may have the potential as an admixed tree species forming a transitory meso-thermophilous habitat in the future. At the same time, silver lime may be limited under increasing drought frequency.

The Carpathian Mountains are an important hotspot of European biodiversity, where geological history, climatic diversity, and altitudinal heterogeneity have determined a great diversity and endemism of vascular plants. The study was conducted in the national park of Piatra Craiului, a distinctive limestone massif in the Southern Carpathians. The dataset included 731 vascular plant species from the study area, of which 35 taxa are endemic to the Carpathians (of the 47 reported in this area), and 18 are classified as species of conservation interest in the Management Plan of the National Park (MP). The distribution of endemic species showed different habitat and altitudinal specificity across 15 vegetation types, including 14 Natura 2000 habitats and one outside the EUR 28 classification. The endemic species showed a bell-shaped altitudinal distribution, peaking at 1600–1700 m and concentrated in high-altitude open habitats rather than forested mid-elevations. The PCA separates endemic species along a main gradient from open, disturbed, light-rich habitats to stable, nutrient- and moisture-rich forest environments, and a secondary gradient related to temperature and soil reaction linked to altitude. Endemic species are predominantly associated with calcareous rocky and grassland habitats and are almost absent from mesophilic and hygrophilous habitats. A positive association between endemic species frequency and the total number of species of conservation interest per plot was detected. We concluded that species of conservation interest (such endemic species) are unevenly distributed among habitat types in the Carpathians, with the greatest diversity and abundance in subalpine rocky and grassland habitats, shaped by altitude and isolation. Although the threatened endemic species are not officially listed by national law, they are indirectly protected by management zonation. In Piatra Craiului the richest habitats in endemic species are included in the designated zones of the national park with the highest protection regime, according to the National Park’s Management Plan. Moreover, this territory is included in a Natura 2000 site (ROSAC0194 Piatra Craiului) ensuring an additional level of protection for the habitats where endemic species are found.

This report presents the content of a database with phytosociological relevs of oak and mixed oak forests from Romania (Vegetation Database of Oak Forests of Romania, GIVD ID EU-RO-005). This includes vegetation-plots in which oak species (Quercus robur s.l., Q. petraea s.l., Q. cerris, Q. frainetto, Q. pubescens s.l. ), hornbeam (Carpinus betulus) or lime (Tilia cordata, T. tomentosa) are dominants or co-dominants. So far, 4,398 relevs are stored in TURBOVEG format, using 160 sources published works, PhD thesis and records of research projects. It is estimated that this sources cover 70-75% of the total relevs available of this kind. Except species data, 65-85% of relevees have basic environmental information and all have geographical coordinates mostly derived from localities or toponyms. Its development started from the need of a unified classification of forest vegetation at a national level, but also with the hope that it could serve for a regional revision of syntaxonomy. So far, using the information from this database, two papers were published and other two are planned.