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.

Between 2011 and 2016 we surveyed 42 sites of coastal salt marshes of Croatia. We confirmed the occurrence of several rare and endangered plant species. Ten of them are included in the Red List of Croatia; critically endangered (CR) Eleocharis uniglumis, Triglochin barrelieri and T. maritima, endangered (EN) Carex divisa and C. extensa, vulnerable (VU) Parapholis incurva, Salsola soda and Suaeda maritima and category data deficient (DD) Limonium virgatum and Puccinellia festuciformis. We also report localities of other rare taxa of salt marshes like Allium telmatum, Tripolium pannonicum subsp. tripolium, Juncus gerardii, Parapholis filiformis, Plantago cornuti, Samolus valerandi and Scorzonera parviflora. Several plant species are endangered. Their habitats, salt marshes were converted into fields or destructed by construction for developing tourist infrastructure. Today only a part of the remained areas are under protection.

Little is known about the suite of ecological conditions under which characteristic species may continue to develop under the pressure of recent habitat deterioration. We aimed to determine the niche of three indicator species of the priority habitat Pannonic salt steppes and to find out how their vegetation composition, land use, and soil chemistry mirror the current condition of their typical habitat. A plot-based vegetation survey was conducted in degraded and in pristine (reference) inland salt steppes in East-Central Europe. We confirmed decreased habitat quality at their northern geographical limit. Most of the sites there showed a strong prevalence of generalists (e.g., Elytrigia repens) and lack of specialists, both resulting from lowered habitat extremity and inappropriate land use (abandonment). A small proportion of plots (19%) were in the same good condition as the reference vegetation in the central area. Soil analyses revealed that the studied halophytes are able to persist on desalinized soils if the land use is suitable. The occurrence of the annual Camphorosma annua (Amaranthaceae) was driven largely by abiotic stress; grazing alone is insufficient for its long-term persistence, while the perennial Artemisia santonicum (Asteraceae) and Tripolium pannonicum (Asteraceae) have higher survival chances as they are able to coexist with generalists. Overall habitat quality can be reliably determined from the analyzed ecological conditions of indicator species. The outcomes of the presented work are relevant for conservation practice and can serve as a quick tool for assessing the current stage of other grassland habitats.

This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: green alga Cosmarium crenulatum, fungi Calvatia fragilis, Hypoxylon fuscum, Myriostoma coliforme and Zeus olympius, mosses Antitrichia curtipendula, Buxbaumia viridis, Homalothecium meridionale, Physcomitrium arenicola, Sphagnum inundatum and Syntrichia calcicola, monocots Anacamptis ? nicodemi nothosubsp. nicodemi, Ornithogalum montanum and Parapholis incurva and dicots Cardamine waldsteinii and Suaeda salsa.