Ellenberg-type indicator values for European vascular plant species

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Prepared by Lubomír Tichý, Irena Axmanová and Milan Chytrý

Recommended area for safe application of the harmonized European dataset of indicator values (image from the original article).

The system of indicator values for vascular plants proposed by the famous German plant ecologist Heinz Ellenberg has been widely used in Europe for the bioindication of environmental conditions. Ellenberg provided an expert-based estimate of the niche position of each species on ordinal scales representing gradients of light, temperature, continentality, moisture, soil reaction, nutrients and salinity. By averaging these “Ellenberg indicator values” across all species present at a given site, we can estimate environmental conditions at that site.

The original dataset of Ellenberg indicator values included most plant species from Germany and adjacent areas. Inspired by the success of the Ellenberg indicator values in Central Europe, plant ecologists in other European regions developed similar systems, including species not found in Ellenberg’s tables and adjusting the values to reflect the changing niches of species in other regions. Currently, there are more than 30 regional systems of indicator values in Europe, some using Ellenberg’s scales, and others using different scales.

Unfortunately, there was no international system of indicator values applicable across larger areas. Therefore, we selected regional indicator systems that used the same scales as the original Ellenberg indicator values. We call them “Ellenberg-type indicator values” because they use the same approach as Ellenberg, but the values were estimated by authors other than Ellenberg. Using a series of regression analyses, we carefully tested all indicator values in each of these systems for their compatibility with the original Ellenberg scales. Those that deviated were rejected. Finally, we selected indicator values for light, temperature, moisture, soil reaction, nutrients and salinity from 11 regional systems that we were confident were compatible with the Ellenberg dataset. We calculated mean values for species based on these datasets plus the original Ellenberg dataset and added entirely new values for nearly 400 species based on an analysis of co-occurrences in vegetation plots from the European Vegetation Archive (EVA).

Our harmonized European dataset contains indicator values for 8908 vascular plant species and some species aggregates. It is not the entire European flora, but this selection includes almost all widespread and common European species. When we took a dataset of 1.8 million vegetation plots from EVA, at least one indicator value was available for 99.7% of species occurrences in this dataset. Consequently, this dataset can be safely used for most European vegetation plots. However, researchers should be cautious when using it in marginal areas such as the northernmost and easternmost parts of Europe, the southern Iberian Peninsula and the southern Balkan Peninsula.

We also recognize that for regional studies, using regional datasets may yield more reliable results than using a European dataset that averages species’ environmental relationships across large areas. Nevertheless, a significant advantage of our dataset is that it uses the same scales as most regional datasets. Therefore, species that are missing from regional datasets can be supplemented from our new dataset.

The dataset is freely available in the Zenodo repository, where future updates will also be published. To facilitate the use of the dataset, we provide on the FloraVeg.EU website a combined dataset of European Ellenberg-type indicator values and European disturbance indicator values that we developed under the lead of Gabriele Midolo (Midolo et al. 2023). Users of the JUICE program can also find a file for JUICE at https://www.sci.muni.cz/botany/juice/?idm=10. All these datasets use species concepts and names following the Euro+Med PlantBase, with minor additions and adjustments following the expert system for EUNIS Habitat Classification (Chytrý et al. 2020). Consequently, they are ready to use in studies of European vegetation based on EVA plots and other data.

This is a plain language summary for the paper of Tichý, L., Axmanová, I., Dengler, J., Guarino, R., Jansen, F., Midolo, G., Nobis, M.P., Van Meerbeek, K., Aćić, S., Attorre, F., Bergmeier, E., Biurrun, I., Bonari, G., Bruelheide, H., Campos, J.A., Čarni, A., Chiarucci, A., Ćuk, M., Ćušterevska, R., Didukh, Y., Dítě, D., Dítě, Z., Dziuba, T., Fanelli, G., Fernández-Pascual, E., Garbolino, E., Gavilán, R.G., Gégout, J.-C., Graf, U., Güler, B., Hájek, M., Hennekens, S.M., Jandt, U., Jašková, A., Jiménez-Alfaro, B., Julve, P., Kambach, S., Karger, D.N., Karrer, G., Kavgacı, A., Knollová, I., Kuzemko, A., Küzmič, F., Landucci, F., Lengyel, A., Lenoir, J., Marcenò, C., Moeslund, J.E., Novák, P., Pérez-Haase, A., Peterka, T., Pielech, R., Pignatti, A., Rašomavičius, V., Rūsiņa, S., Saatkamp, A., Šilc, U., Škvorc, Ž., Theurillat, J.-P., Wohlgemuth, T., Chytrý, M., published in the Journal of Vegetation Science (https://doi.org/10.1111/jvs.13168).