The phenological optimum is defined here as a period when most vascular plants in the community are in flower. This period usually corresponds to the period of the peak biomass of vegetation. For vegetation types that have two or more dominant life forms with different phenological optima, the optimum is considered separately for each dominant life form. Some vegetation types (e.g. annual weed or ruderal vegetation) have two or three groups of species with different phenological optima, even within the same life form, resulting in different spring, summer and autumn aspects. Two or three phenological optima are recorded for these types. In the case of marine, some types of aquatic and monocarpic vegetation that may look similar throughout the year or at least throughout the growing season (e. g., Zosterion, Potamogetonion, Ranunculion aquatilis, Littorellion, Greenovion), the phenological optimum is considered to be the time of flowering of the dominant species or most of the species in the community. Phenological optimum categories have been defined primarily based on Central European phenological patterns and applied to vegetation in other regions of Europe. More than one phenological optimum was reported for vegetation types with an optimum that spans more than one category. Assignments to categories were based on field experience, descriptions in various literature sources, and were partially derived from vegetation-plot data.

Categories

• Early spring – March, April
• Late spring – May
• Summer – June, July, August
• Autumn – August, September, October
• Winter – November, December, January, February

Data source and citation

Preislerová, Z. (2022). Phenological optimum. – www.FloraVeg.EU.

Salinity refers to the concentrations of readily soluble salts (especially sodium, potassium, calcium, and magnesium sulphates, chlorides, and carbonates) in soil or water.

• Non-saline substrate has no or very low concentrations of soluble salts
• Slightly saline or brackish substrate has a low to moderate concentration of soluble salts
• Saline substrate has a high concentration of soluble salts

Categories

• Non-saline
• Slightly saline or brackish
• Saline

Data source and citation

Preislerová, Z. (2022). Salinity. – www.FloraVeg.EU.

The organic component of soil consists of plant and animal detritus in various stages of decomposition. Two categories are defined according to the predominant mineral or organic component. Aquatic vegetation types that do not root in soil are not classified.

• Mineral soil – the mineral soil component predominates over the organic component
• Organic soil – the organic soil component predominates over the mineral component

Categories

• Mineral soil
• Organic soil

Data source and citation

Preislerová, Z. (2022). Soil organic matter. – www.FloraVeg.EU.

Vegetation zones are large areas of relatively uniform climate and vegetation. These zones often correspond to other land classification units such as biogeographical regions, ecoregions or biomes (Schultz 2005, Rivas-Martínez et al. 2004a, Mucina et al. 2016, Dinerstein et al. 2017, Bruelheide et al. 2018, EEA 2018). However, such classification systems are inconsistent across Europe and differ in the number of units defined and in the position of boundaries between them. Here, we propose a system largely based on a combination of the Biogeographic and Bioclimatic Maps of Europe by Rivas-Martínez (2004a, b) and European Biogeographical Regions (EEA 2018). We found this system optimal for describing the distribution of European phytosociological alliances (Mucina et al. 2016, Preislerová et al. 2022). It includes nine horizontally divided categories (Arctic, Boreal, Hemiboreal, Nemoral, Forest-steppe, Steppe, Submediterranean, Mediterranean and Macaronesian; Fig. 1) and three vertical categories (Oroboreal, Orotemperate and Oromediterranean) for alpine regions.

The assignment of vegetation types to zones is mainly based on the distribution maps of the European alliances (Preislerová et al. 2022). Since these maps do not provide sufficient details such as point distribution, we also used information from various literature and expert knowledge.

We defined the following zones:

• Arctic – Arctic Biogeographical Region of Russia, Greenland, Svalbard
• Boreal – northern part of the Boreal Biogeographical Region of Russia, Finland, Sweden and Norway (except for the southern parts of these three countries), Iceland, Faroe Islands
• Hemiboreal – southern part of the Boreal Biogeographical Region of Russia, Estonia, Latvia, Lithuania, Belarus, the Kaliningrad Region of Russia, the southern part of Sweden except for the Skåne Peninsula and the southernmost parts of Finland and Norway
• Nemoral – Atlantic and partly Continental Biogeographical Regions, including the British Isles, France with the exception of the Mediterranean part, the Atlantic part of the Iberian Peninsula, the Benelux countries, Denmark, Germany, Poland, Czechia, Slovakia, Switzerland, Austria, Alpine part of Italy, Slovenia, the Alpine Biogeograpical Region of Romania and Bulgaria, the Alpine and Continental Biogeographical Regions of Ukraine, the Continental Biogeographical Region of Russia, the higher elevations of the Southern Urals, the Caucasus countries and the Russian part of the Great Caucasus
• Forest-steppe – Hungary, the extra-Carpathian parts of Romania, the Pannonian Biogeographical Region in northern Serbia, northern Moldova, the transition zone between the Continental and Steppic Biogeographical Regions in Ukraine and Russia and the mountain fringes of the Southern Urals
• Steppe – Steppic part of Ukraine and Russia, southern Moldova, northern Crimea, low-lying areas in the Caucasus countries and in the Russian part of the Great Caucasus
• Submediterranean – the northern interior part of Spain and the border areas between the Mediterranean and Continental Biogeographical Regions, including parts of France, Italy, Croatia, Bosnia and Herzegovina, Serbia, Kosovo, Macedonia, Montenegro, Albania, Bulgaria, Turkey and the southern part of Crimea; vegetation types occurring in the Supramediterranean elevation belt within the Mediterranean Biogeographical Region are also included in the Submediterranean zone
• Mediterranean – Portugal, southern parts of Spain, France and Italy, the coastal areas of the Adriatic Sea, Greece and all Mediterranean islands; only vegetation types occurring in the Inframediterranean, Thermomediterranean and Mesomediterranean belts are included in this zone
• Macaronesian – Canary Islands, Madeira and Azores
• Oroboreal – high elevations in the Scandinavian Mountains, Northern and Central Urals; vegetation types from the elevations around or above the timberline are included
• Orotemperate – Cantabrian Mountains, Pyrenees, Massif Central, Alps, Northern and Central Apennines, Vosges, Schwarzwald, Harz, Sudetes, Bohemian Forest, Carpathians, Dinarides, central Balkan mountain systems, Caucasus; vegetation types from the subalpine, alpine and nival elevational belts are included
• Oromediterranean – mountain systems of the Iberian Peninsula south of the Cantabrian Range and the Pyrenees, Cevennes, mountain systems of the Mediterranean islands, Southern Apennines, Greek mountain systems; only vegetation types from the Oromediterranean to Cryomediterranean elevation belts are included

Data source and citation

Preislerová, Z. (2022). Vegetation zone. – www.FloraVeg.EU.

Further references

Bruelheide H., Dengler J., Purschke O., Lenoir J., Jiménez-Alfaro B., Hennekens S.M. ... Jandt U. (2018) Global trait–environment relationships of plant communities. Nature Ecology & Evolution, 2, 1906–1917. https://doi.org/10.1038/s41559-018-0699-8
Dinerstein E., Olson D., Joshi A., Vynne C., Burgess N.D., Wikramanayake E. … Saleem M. (2017) An ecoregion-based approach to protecting half the terrestrial realm. BioScience, 67/6, 534–545. https://doi.org/10.1093/biosci/bix014
EEA (2018) Mapping Europe’s Ecosystems. Copenhagen: European Environment Agency. https://doi.org/10.2800/850732
Mucina L., Bültmann H., Dierßen K., Theurillat J. P., Raus T., Čarni A., … & Tichý L. (2016) Vegetation of Europe: hierarchical floristic classification system of vascular plant, bryophyte, lichen, and algal communities. Applied Vegetation Science, 19 (Suppl. 1), 3-264. https://doi.org/10.1111/avsc.12257
Preislerová Z., Jiménez-Alfaro B., Mucina L., Berg C., Bonari G., Kuzemko A. … Chytrý M. (2022) Distribution maps of vegetation alliances in Europe. Applied Vegetation Science, 25, e12642. https://doi.org/10.1111/avsc.12642
Rivas-Martínez S., Penas A. & Díaz T. E. (2004a). Bioclimatic map of Europe - Bioclimates. Cartographic Service, University of León. https://doi.org/10.5616/gg110001
Rivas-Martínez S., Penas A. & Díaz T.E. (2004b) Biogeographic Map of Europe. Cartographic Service University of León.
Schultz J. (2005) The ecozones of the world. The ecological division of the geosphere, 2nd edition. Berlin, Springer.

Azonality is defined by locally specific abiotic conditions that prevent the development of vegetation types that occupy large areas under similar climatic conditions (zonal vegetation) and promote the development of specific, locally confined vegetation types (azonal vegetation). Some vegetation types may be zonal in some areas but azonal in others, e.g. some types of arctic-alpine or mire vegetation are zonal in northern Europe but azonal in central or southern Europe. Fringe vegetation, which develops at the boundary between forests and herbaceous vegetation on widespread soil types, is zonal but included in the special category of Ecotone because of its patchy occurrence.

The following types of azonality are recognized:

• Marine – sea littoral with sea-grass vegetation
• Coastal wetlands – permanently wet dune slacks affected by saltwater
• Inland aquatic – aquatic vegetation of freshwater lakes and ponds
• Inland wetland – places with a high level of fresh groundwater or near springs; the soil is saturated with water throughout the year or for part of the year
• Riverine – vegetation that develops along streams and in stream beds
• Shallow soil – often dry or rapidly drying, usually with low nutrient availability
• Steep slope – slopes with an inclination greater than 35°, usually affected by erosion, fast water runoff, and in some places in alpine areas, by avalanches
• Rock – outcrops and cliffs without soil, stressed by lack of water and extreme temperatures; develops patchily in crevices, on ledges and terraces
• Scree – unstable mixture of rock fragments that are moved downward by gravity
• Dunes and beaches – coastal or inland sandy habitats with extreme temperature fluctuations, low water storage, low nutrient content, and limited nutrient availability
• Ultramafic and heavy-metal soil – outcrops or shallow soils on peridotite, ophiolite, serpentinite and other rocks that contain high concentrations of heavy metals such as Fe, Mn, Cu, Cr, Ni, Pb, Co, and Cd, which are toxic to many plant species; some heavy-metal soils are also anthropogenic and occur on mining tailing piles
• Gypsum – layers of hydrated calcium sulfate that forms a hard surface crust that is difficult for plants to penetrate; gypsum soils are often deficient in macronutrients and dry out due to heavy water runoff
• Badland – landscape on clay substrate subject to severe erosion during heavy rain storms, resulting in steep slopes; upper soil layers dry out during dry periods and accumulate salt
• Saline – habitats with high concentrations of soluble salt ions (sodium, potassium, calcium and magnesium sulfates, chlorides and carbonates) that are toxic to many plant species
• Mediterranean eroded slope – eroded slopes both at low (usually on lava flows) and high elevations of the Mediterranean mountain ranges, characterized by disturbances combined with summer drought and winter frost
• Snow patch – arctic and alpine habitats where snow melts much later than in the surrounding area, resulting in a short growing season and locally increased moisture
• Alpine, snow-protected – leeward slopes or depressions in high mountains where snow accumulates, protecting vegetation from frost and providing soil with moisture from snowmelt; unlike in snow patches, snow melts early in the season
• Alpine, wind-exposed – high-mountain sites exposed to wind; in winter, wind blows away snow and exposes vegetation to frost; in summer, wind causes desiccation
• Salt-sprayed site – coastal cliffs and slopes affected by horizontal precipitation from the sea, which affects vegetation by salt spray
• Foggy site – wind-facing slopes affected by clouds that bring moisture to otherwise dry sites and reduce direct solar radiation
• Ecotone – linear vegetation types that develop at the transition between two vegetation types of different structure, e.g. forest and grassland
• Zonal – vegetation and habitat types other than those defined above that occur over large areas under the abiotic conditions that prevail in the region

Categories

• Marine
• Coastal wetlands
• Inland aquatic
• Inland wetland
• Riverine
• Shallow soil
• Steep slope
• Rock
• Scree
• Dunes and beaches
• Ultramafic and heavy-metal soil
• Gypsum
• Badland
• Saline
• Mediterranean eroded slope
• Snow patch
• Alpine, snow-protected
• Alpine, wind-exposed
• Solt-sprayed site
• Foggy site
• Ecotone
• Zonal

Data source and citation

Preislerová, Z. (2022). Azonality. – www.FloraVeg.EU.