Plant species display a range of structural, physiological and morphological adaptations to environmental gradients. Various authors proposed different categories of plant life forms (e.g., Du Rietz 1931; Raunkiær 1934; Ellenberg & Mueller-Dombois 1967). The categories of life forms defined here are based on a combination of traits important for vegetation structure in Europe, including plant height, woodiness, branching type of woody plants (trees vs shrubs), leaf type, life span (annual vs perennial), and habitus (e.g., graminoid, non-graminoid, fern, succulent, aquatic plant). Broad taxa of cryptogams (ferns, bryophytes and lichens) are also considered here as separate life forms based on their specific morphological and ecophysiological features (except for aquatic cryptogams, which are grouped with other aquatic plants).

The dominant life form is the plant life form that usually attains the highest cover in at least one of the four main vegetation layers (tree, shrub, herb or moss layer). More than one dominant life form is given for vegetation types with well-differentiated vegetation layers. For example, conifer trees, dwarf shrubs and bryophytes can be given for a boreal forest alliance, each life form being dominant in a different vegetation layer. However, layers that have, on average, much lower cover than other layers in the given alliance are not considered. We do not report the dominant life form for the layers with a mean cover lower than 20% of the mean cover of the layer with the highest cover. For example, in a grassland vegetation type with a mean herb layer cover of 80%, shrub layer of 5% and moss layer of 10%, we only include the dominant life form of the herb layer. More than one life form may be reported for the same layer if different life forms dominate this layer at different sites (e.g., perennial graminoids and perennial non-graminoid herbs in a meadow alliance).

Some species may have different life forms depending on the environment or region (e.g., tree in lowlands vs shrub near the timberline). In such cases, the life form prevailing in the given alliance is reported. Tree saplings in the shrub layer are considered trees.

Categories:

• Coniferous trees – usually evergreen, single-trunk woody plants with either needle-like or scale-like leaves; examples: Abies spp., Cupressus sempervirens, Juniperus thurifera, Larix spp., Picea spp., Pinus nigra.
• Broad-leaved deciduous trees – single-trunk woody plants that shed all their leaves at the beginning of the cold season (examples: Fagus spp., Fraxinus spp., Ficus carica, Ostrya carpinifolia, Quercus petraea, Sorbus aucuparia) and marcescent trees that keep their leaves dry on the twigs in winter (examples: Quercus pubescens)
• Broad-leaved evergreen trees – single-trunk woody plants with small (sclerophyllous) or large (laurophyllous) evergreen leaves; examples: Apollonias barbujana, Ceratonia siliqua, Laurus nobilis, Olea europaea, Quercus ilex, Q. suber
• Palms – evergreen plants with cylindrical stems that lack secondary growth and with crowns of large feathered or fan-shaped leaves; examples: Chamaerops humilis, Phoenix spp.
• Coniferous shrubs – evergreen woody plants taller than 50 cm with stems branching at the base with either needle-like leaves (examples: Juniperus communis, Pinus mugo subsp. mugo) or scale-like leaves (example: Juniperus sabina); tree saplings in the forest shrub layer are not included
• Broad-leaved deciduous shrubs – woody plants taller than 50 cm with stems branching at the base that shed all their leaves at the beginning of the cold season; tree saplings in forest shrub layers are not included; examples: Cornus sanguinea, Corylus avellana, Prunus spinosa, Sambucus nigra
• Broad-leaved evergreen shrubs – evergreen woody plants taller than 50 cm with stems branching at the base with small (sclerophyllous) or large (laurophyllous) evergreen leaves; tree saplings in forest shrub layers are not included; examples: Arbutus unedo, Clethra arborea, Maytenus canariensis, Nerium oleander, Nicotiana glauca, Phillyrea angustifolia, Pistacia lentiscus, Rhamnus alaternus, Salvia canariensis
• Microphyllous shrubs and small trees – evergreen or deciduous non-coniferous woody plants taller than 50 cm and shorter than 6 m with tiny, scaly or needle-like leaves; examples: Erica arborea, E. scoparia, Myricaria spp., Tamarix spp.
• Broom shrubs – woody plants taller than 50 cm with stems branching at the base; they resemble a broom and assimilate primarily through slender green branches; they have sparse, small leaves that drop in summer to reduce water loss; in some species, small branches are transformed into thorns; examples: Cytisus ruthenicus, C. scoparius, C. supranubius, Genista corsica, G. florida, G. scorpius, Launaea arborescens, Retama spp., Ulex boivinii, U. europaeus
• Dwarf shrubs – small woody or semi-woody plants (chamaephytes) with most of their overwintering buds located up to 50 cm above the soil surface; small suffruticose plants with herbaceous branches and cushion-like shrubs are also included here; examples: Artemisia hololeuca, Astracantha sicula, Bupleurum fruticescens subsp. spinosum, Calluna vulgaris, Daphne glomerata, Dryas spp., Echinospartum horridum, Ephedra distachya, Erica carnea, Euphorbia spinosa, Genista hispanica, Helichrysum stoechas, Loiseleuria procumbens, Phyllodoce caerulea, Prunus prostrata, Salix herbacea, Thymus spp., Vaccinium myrtillus, Vella spinosa
• Woody lianas – creeping or climbing evergreen or deciduous plants with woody bases; example: Hedera spp., Smilax aspera, Vitis spp.
• Perennial graminoids – grass-like herbaceous plants of the order Poales (Cyperaceae, Juncaceae, Poaceae, Typhaceae) that live for more than one year
• Perennial non-graminoid herbs – herbaceous plants not belonging to Poales that live for more than one year; leaves are both in rosettes or on long stems; non-woody lianas, clubmosses, horsetails, hemicryptophytes, geophytes and helophytes are included here; some of them can have a cushion-like form; examples: Androsace villosa, Butomus umbellatus, Calystegia sepium, Cerastium arcticum, Dactylorhiza spp., Equisetum spp., Galanthus spp., Mentha spp., Onopordum spp., Plantago media, Verbascum spp.
• Ferns – terrestrial or epiphytic herbaceous plants with feathery or tongue-like fronds that reproduce by spores; examples: Asplenium spp., Blechnum spp., Dryopteris spp., Ophioglossum spp., Woodsia spp.; aquatic ferns are classified as aquatic macrophytes; horsetails (Equisetopsida) are classified as perennial non-graminoid herbs
• Succulents – annual or perennial plants (both hemicryptophytes and chamaephytes) with thick fleshy leaves or stems; examples: Aeonium spp., Anabasis aphylla, Astydamia spp., Climacoptera spp., Crithmum maritimum, Euphorbia canariensis, E. lamarckii, E. regis-jubae, Kalidium spp., Salicornia spp., Salsola spp., Sedum spp., Sempervivum spp., Suaeda spp.
• Annual graminoids – grass-like herbaceous plants (Cyperaceae, Juncaceae, Poaceae) that complete their life cycle during one growing season or start to germinate in the autumn and reproduce in the following year (winter therophytes or biennial therophytes); they survive harsh conditions during unfavourable seasons as seeds; examples: Aegilops spp., Aira spp., Anisantha tectorum, Brachypodium distachyon, Isolepis setacea, Juncus bufonius, Vulpia spp.
• Annual non-graminoid herbs – herbaceous plants other than Cyperaceae, Juncaceae and Poaceae that complete their life cycle during one growing season or start to germinate in the autumn and reproduce the following year (biennial therophytes); they survive harsh conditions during unfavourable seasons as seeds; examples: Bidens cernua, Bupleurum rotundifolium, Gypsophila elegans, Myosurus minimus, Plantago lagopus, Ranunculus sardous, Sisymbrium loeselii, Thlaspi arvense
• Floating aquatic plants – vascular plants or bryophytes floating on or below the water surface (pleustophytes); examples: Lemna spp., Riccia fluitans, Salvinia natans
• Rooted aquatic plants – vascular plants, bryophytes or macroalgae living in water and rooted in the bottom, some of them submerged and others with natant leaves; examples: Chara spp., Cinclidotus spp., Fontinalis spp., Isoetes spp., Marsilea spp., Myriophyllum spp., Nymphaea spp., Persicaria amphibia, Potamogeton spp., Ranunculus fluitans, Zostera spp.
• Bryophytes – non-aquatic mosses, liverworts and hornworts; examples: Bazzania spp., Dicranum spp., Gymnomitrion spp., Polytrichum spp., Sphagnum spp.
• Lichens – lichenized fungi; examples: Cladonia spp., Parmelia spp.

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Further references

Du Rietz, G.E. (1931) Life-forms of terrestrial flowering plants I. Acta Phytogeographica Suecica, 3 (1), 1–95.
Ellenberg, H. & Mueller-Dombois, D. (1967) A key to Raunkiaer plant life-forms with revised subdivisions. Berichte des Geobotanischen Institutes ETH, Stiftung Rübel, 37, 56–73.
Raunkiær, C. (1934) The life forms of plants and statistical plant geography. Oxford: Clarendon Press.

The phenological optimum is defined here as a period when most of the species in the community (or the dominant species in species-poor communities) are flowering. This period usually corresponds to the peak of aboveground biomass in the community. In vegetation dominated by ferns, the phenological optimum corresponds to the period of highest biomass. In vegetation types that have shifted phenological phases for different species groups, more than one phenological optimum is given. For example, temperate deciduous floodplain forests have two phenological optima associated with different life forms: early spring (flowering of spring geophytes and trees) and summer (maximum biomass of tree leaves and flowering and maximum biomass of shade-adapted hemicryptophytes such as Urtica dioica). Some types of annual weed or ruderal vegetation may comprise two or three groups of species with the same life form but different phenological optima, resulting in different spring, summer and autumn aspects. Some vegetation types have a long phenological optimum spanning at least two periods defined here. More than one phenological optimum is given in such cases. If spring flowering of deciduous trees or shrubs precedes leaf development, and no other life form is flowering, the time of fully developed foliage (the highest biomass), which usually corresponds with the flowering of other plants, is considered the phenological optimum. The phenological optimum of bryophytes and lichens is not considered.

Phenological optimum categories were defined primarily based on phenological patterns in the Central European lowlands, which roughly correspond to the mean phenological stages in vegetation types across Europe. However, the assessment considers that spring phases start earlier in the Southern European lowlands and later in the Central European mountains and Northern Europe. Because there is little information on the phenological optimum in the phytosociological literature, category assignments were based largely on field experience and the phenology of dominant or other common species in each vegetation type.

Categories:

• Early spring – March, April (it can start earlier in Southern European lowlands and end later in Central European mountains and Northern Europe)
• Late spring – May (it can start earlier in Southern European lowlands and end later in Central European mountains and Northern Europe)
• Summer – June, July, August
• Autumn – September, October, November
• Winter – December, January, February (it can end in January in the Southern European lowlands)

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Substrate moisture reflects the availability of water to plants during the growing season.

Categories:

• Dry substrate is characterized by a low groundwater table and low water-holding capacity; substrates with a higher water-holding capacity that are seasonally very dry due to low precipitation (e.g., clayey soils in the Mediterranean or semidesert areas) are also in this category
• Mesic substrate holds a moderate amount of soil moisture throughout the year without pronounced drought or waterlogging
• Intermittently wet substrate is occasionally or seasonally flooded with rainwater or has a periodically high groundwater table and then dries out; such conditions occur in continental floodplains, depressions, shallow pans, temporary ponds and streams
• Moist to wet substrate is characterized by a permanently high groundwater table that is shallow below the soil surface, at the soil surface, or for some very short period also above the soil surface
• Water is the category for the environments in which the water table is above the soil surface for most of the growing season

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Substrate reaction is measured as the pH of soil solution or water. Reaction categories are defined by pH thresholds following USDA (2017). However, only three categories are used because the exact ranges of pH values are unknown for many vegetation types, and the reaction category had to be estimated based on bedrock type and reaction indicator values (Dengler et al., 2023; Tichý et al., 2023) of diagnostic, constant or dominant species for each vegetation type.

Categories:

• Acid substrate has a pH of up to 6.0 and a low base content
• Slightly acid to neutral substrate has a pH between 6.0 and 7.3 and a moderate base content
• Alkaline substrate has a pH above 7.3 and a high content of calcium or other basic cations

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Further references

Dengler, J., Jansen, F., Chusova, O., Hüllbusch, E., Nobis, M.P., Van Meerbeek, K. et al. (2023) Ecological Indicator Values for Europe (EIVE) 1.0. Vegetation Classification and Survey, 4, 7–29. https://doi.org/10.3897/VCS.98324
Tichý, L., Axmanová, I., Dengler, J., Guarino, R., Jansen, F., Midolo, G. et al. (2023) Ellenberg-type indicator values for European vascular plant species. Journal of Vegetation Science, 34, e13168. https://doi.org/10.1111/jvs.13168
USDA (2017) Soil survey manual. Washington, DC: United States Department of Agriculture.

Salinity refers to the concentrations of soluble salts (especially carbonates, chlorides and sulphates of calcium, magnesium, sodium and potassium) in soil or water. In coastal areas, salinity can be caused by sea surges, tides, storms, salt spray from the sea and the mixing of freshwater and seawater in estuaries. In inland areas, salinity can be high due to mineral-rich springs or salt accumulation in the soil from salt-rich sediments in dry climates with high evaporation. Measurements of salinity are rare; therefore, salinity is usually estimated from the occurrence of plants along a soil-salinity gradient.

Categories:

• Non-saline substrate has no or very low concentrations of soluble salts; the vegetation contains no halophytes
• Subsaline substrate has low to moderate concentrations of soluble salts; vegetation is composed of a mixture of halophytes and glycophytes (non-halophytic plants)
• Saline substrate has a high concentration of soluble salts; vegetation is dominated by halophytes

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Nutrient status refers to the concentration of available nitrogen, phosphorus and potassium in soil or water.

Categories:

• Oligotrophic substrate or water has low nutrient availability; vegetation has low productivity; dystrophic environments are also included here
• Mesotrophic substrate or water has moderate nutrient availability; vegetation has moderate productivity
• Eutrophic substrate or water has a high amount of available nutrients, especially nitrogen and phosphorus; vegetation has high productivity
• Hypertrophic substrate or water has a very high amount of available nutrients, often due to anthropogenic eutrophication; vegetation has very high productivity

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Soil organic matter consists of remains of dead plants and animals at various stages of decomposition. The following categories are distinguished according to the relative proportion of mineral or organic components. Aquatic vegetation types that do not root in soil are not classified.

Categories:

• Poorly developed soil – rock outcrops, gravel, sand or clay with poorly developed soil
• Developed mineral soil – developed soil in which the mineral soil component predominates over the soil organic matter, or both components are represented equally; forest soils with a layer of humus are also included here, provided the mineral component predominates in the topsoil
• Organic soil – the organic soil component predominates over the mineral component

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Vegetation regions defined here are large areas with relatively uniform climates and vegetation. These regions partially correspond to other land classification units such as biogeographical regions, ecoregions or biomes (Rivas-Martínez et al., 2004a; Schultz 2005; EEA 2016; Mucina et al., 2016; Dinerstein et al., 2017; Bruelheide et al., 2018). However, these classification systems are inconsistent across Europe, differ in the number of units and the location of boundaries between them, and some of them do not consider vegetation as the main classification criterion. Here, we propose a system based mainly on a combination of the Biogeographic and Bioclimatic Maps of Europe by Rivas-Martínez (2004a, 2004b), European Biogeographical Regions (EEA 2016) and Ecoregions by Dinerstein et al. (2017).

The assignment of vegetation types to vegetation regions is partly based on the distribution maps of 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.

Categories (regions):

• Arctic – Arctic Biogeographical Region in the northernmost part of the European mainland, Greenland and Svalbard
• Boreal – northern part of the Boreal Biogeographical Region in the European part of Russia, Finland, Sweden and Norway (except for the southern parts of these three countries), Iceland and the Faroe Islands
• Hemiboreal – southern part of the Boreal Biogeographical Region in the European part of Russia, Estonia, Latvia, Lithuania, Belarus, the Kaliningrad Region of Russia and the adjacent part of Poland, the southern part of Sweden except for the Skåne Peninsula and the southernmost parts of Finland and Norway
• Nemoral-Atlantic – Atlantic Biogeographical Region including Ireland, Great Britain, western Denmark, northwestern Germany, Benelux, northern and western France and the northern Iberian Peninsula
• Nemoral-Continental – Pyrenees, eastern France, southeastern Belgium, Luxembourg, eastern and southern Germany, eastern Denmark, Skåne Peninsula, Poland, Czechia, Slovakia, Switzerland, Austria, Italian Alps, northern Slovenia, southwestern Hungary, Ukrainian and Romanian Carpathians, and the nemoral forest zone of Belarus, Ukraine and Russia
• Nemoral-Submediterranean – northern Italy except the Alps, southern Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Kosovo, North Macedonia, Montenegro, eastern Albania, Bulgaria, northern part of Greece and European Turkey, southern Crimea, the Greater Caucasus, Georgia, Armenia and western and southern Azerbaijan
• Forest-steppic – the Pannonian Biogeographical Region in southeastern Czechia, southern Slovakia, eastern Austria, Hungary and northern Serbia, the extra-Carpathian parts of Romania, forest-steppe zone in Ukraine, Moldova and Russia, and the mountain fringes of the Southern Urals
• Steppic – steppe zone in Ukraine, Moldova and Russia, low-lying areas in the Caucasus countries and the Russian part of the Greater Caucasus
• Semidesertic – extremely dry eastern part of the Steppic Biogeographical region around the Caspian Sea
• Mediterranean – Iberian Peninsula except for its Atlantic part and the Pyrenees, southern France, southern and southwestern Italian Peninsula, the coastal areas of the Balkan Peninsula, Greece and all the Mediterranean islands
• Macaronesian – Azores, Madeira and Canary Islands

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Further references

Bruelheide, H., Dengler, J., Purschke, O., Lenoir, J., Jiménez-Alfaro, B., Hennekens, S.M. et al. (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. et al. (2017) An ecoregion-based approach to protecting half the terrestrial realm. BioScience, 67, 534–545. https://doi.org/10.1093/biosci/bix014
EEA (2016) Biogeographical regions in Europe. Copenhagen: European Environment Agency. https://www.eea.europa.eu/data-and-maps/figures/biogeographical-regions-in-europe-2
Mucina, L., Bültmann, H., Dierßen, K., Theurillat, J.-P., Raus, T., Čarni, A. et al. (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. et al. (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. León: Cartographic Service, University of León. https://doi.org/10.5616/gg110001
Rivas-Martínez, S., Penas, A. & Díaz, T.E. (2004b) Biogeographic Map of Europe. León: Cartographic Service, University of León.
Schultz, J. (2005) The ecozones of the world. The ecological division of the geosphere, 2nd edition. Berlin: Springer.

The elevational vegetation belts reflect the vertical zonation of vegetation in relation to the changing climate with increasing elevation. In the Arctic and Boreal vegetation regions, we distinguish only the Boreo-Arctic lowland and the Boreo-Arctic mountain belts because the distinction between multiple belts is often unclear due to the low timberline in maritime and northern areas. In the Hemiboreal, Nemoral, Forest-steppic, Steppic and Semidesertic vegetation regions, we distinguish lowland, submontane, montane, subalpine, alpine and subnival belts. In the Mediterranean and Macaronesian vegetation regions, we use the division into Inframediterranean, Thermomediterranean, Mesomediterranean, Supramediterranean, Oromediterranean and Cryomediterranean belts. Each elevational belt may shift up or down in any mountain range or region, depending on local environmental conditions.

Categories:

Boreo-Arctic vegetation belts

• Boreo-Arctic lowland – lowland landscape with coniferous forests or a mixture of deciduous and coniferous forests in the Boreal and Hemiboreal vegetation region or with shrub vegetation, heathlands, grassy tundra, snow beds or arctic desert in the Arctic vegetation region
• Boreo-Arctic mountain – mountainous landscape with shrubby vegetation or open deciduous woodlands, heathlands and grasslands in the Boreal or Arctic vegetation regions

Temperate vegetation belts

• Lowland – low-altitude landscapes, including the most thermophilous vegetation types in the given area
• Submontane – transitional landscapes between lowlands and mountains with deciduous forests
• Montane – mountainous landscapes with mixed coniferous-deciduous forests or cool deciduous forests, with an increasing predominance of coniferous forests towards higher elevations or more continental macroclimates
• Subalpine – landscapes around the timberline with open coniferous forests, krummholz, heathlands and grasslands around the timberline
• Alpine – landscapes above the timberline with grasslands and heathlands
• Subnival – landscapes close to the snow line and rocky summits with patchy vegetation dominated by bryophytes and lichens with a low cover of vascular plants

Vegetation belts of the Mediterranean and Macaronesian vegetation regions

• Inframediterranean – lowest elevations of Madeira and the Canary Islands with a warm and arid climate; natural vegetation is dominated by low-growing, succulent, thorny or summer-deciduous shrubs
• Thermomediterranean – a belt at low elevations, usually near the coast, with potential natural vegetation dominated by evergreen sclerophyllous or microphyllous scrub and forests
• Mesomediterranean – a belt characterized by warm summers, mild winters with rare frost and pronounced periods of summer drought, suitable for the cultivation of the olive tree; the natural vegetation of this belt is the evergreen sclerophyllous or laurophyllous forest or sclerophyllous scrub at dry sites
• Supramediterranean – a belt at middle elevations with less pronounced summer drought and regular winter frost; the natural vegetation of this belt is mainly broad-leaved deciduous forest; coniferous forests may occur on humid slopes, while sclerophyllous forests or scrub can occur at dry sites
• Oromediterranean – a belt below and around the timberline, characterized by heaths and pine and juniper forests
• Cryomediterranean – the highest belt of the Mediterranean mountain ranges, located above the timberline; it is characterized by natural grasslands and hedgehog heaths

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Azonality is defined by locally specific substrate or other abiotic conditions that prevent the development of vegetation types that occupy large areas under given macroclimatic conditions (zonal vegetation) and promote the development of specific, localized vegetation types (azonal vegetation). Many azonal vegetation types occur in specific habitats but are confined to a single vegetation zone. Such vegetation types are called intrazonal. Some vegetation types may be zonal in some areas but dependent on local conditions in others, e.g., some types of arctic-alpine or mire vegetation are zonal in Northern Europe but confined to locally specific conditions in Central or Southern Europe. Such occurrences are referred to as extrazonal and are also considered here. Some vegetation types are included in more than one category, e.g., salt-sprayed coastal cliffs are both Rock and Saline.

Categories:

• Marine – sea littoral with sea-grass vegetation
• Aquatic – inland freshwater, brackish and saline lakes, ponds and pools
• Wetland – places with groundwater permanently or frequently at the level of soil surface or slightly above it
• Riverine – rivers, streams and streambeds that may be subject to short-term flooding; both vegetation in the water and on the banks is considered here
• Shallow soil – places with soils that dry out frequently or quickly, have low nutrient levels and do not buffer chemical reaction of the bedrock
• Rock – outcrops and cliffs without soil that are stressed by lack of water and extreme temperatures; vegetation develops patchily in rock crevices, on ledges and terraces
• Scree – an unstable mixture of rock fragments of various sizes that are moved downward by gravity
• Eroded slope – non-rocky steep slopes that are heavily affected by erosion processes
• Sand – coastal or inland sandy habitats with low water storage and low nutrient content
• 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; heavy-metal soils on mine dumps are also included
• Gypsum – outcrops of hydrated calcium sulphate with a hard surface crust that is difficult for plants to penetrate; gypsum soils are often poor in macronutrients and dry out due to heavy water runoff
• Saline – habitats affected by high concentrations of soluble salts (carbonates, chlorides and sulphates of calcium, magnesium, potassium and sodium) in the soil or water
• Snowbed – 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 or cryomediterranean, wind-exposed – high-mountain (alpine or cryomediterranean, or less frequently subalpine or oromediterranean) or arctic (less frequently subarctic) sites exposed to wind; in winter, the wind blows away snow and exposes vegetation to frost; in summer, wind causes desiccation
• Zonal – vegetation types other than those defined above that occur over large areas and reflect macroclimate rather than a particular substrate or other local abiotic conditions; fringe vegetation that develops at the boundary between forests and herbaceous vegetation on widespread soil types is also included here despite its linear nature; this category is included here as a complement to the azonality categories to provide an attribute to all the alliances

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

The successional status reflects the position of vegetation types in the successional series from early successional stages that occur after the emergence of new habitats (primary succession) or after a major stand-replacing disturbance (secondary succession). Some vegetation types are assigned more than one successional stage because they may have different successional statuses in different climatic zones (e.g., some types of scrub can be late successional under dry climates and mid-successional in wet climates).

Categories:

• Early-successional – vegetation developed at recently or frequently intensively disturbed sites (e.g., river bars, trampled sites, and arable fields) or in newly created habitats (e.g., bottoms of drained water bodies, clearings, lava fields and mining sites); it is dominated by short-lived species and may undergo a directional change toward vegetation with a higher proportion of long-lived species; examples include annual-dominated weed or ruderal vegetation
• Mid-successional – vegetation on developed soils that undergoes a directional change; however, in many cases, further succession is prevented by periodic disturbances of moderate or low severity (e.g., floods, avalanches, wind, mowing, grazing and burning); long-lived species predominate over short-lived species; examples include scrub and perennial grasslands in areas where the potential vegetation is a forest
• Late-successional – vegetation that does not undergo directional changes and is not influenced by strong or regular disturbance; it is usually dominated by long-lived plant species and is in dynamic equilibrium with local climate and soil; examples include forests, but also scrub or grasslands in dry or cold climates
• Blocked primary succession – occurs at sites where extreme soil conditions (e.g., rocks, cliffs, scree, walls, gypsum) or other adverse factors (e.g., strong and constant wind) prevent the development to later successional stages; such sites are dominated by long-lived species adapted to extreme conditions

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .

Naturalness expresses the degree to which vegetation has been formed by natural processes or under human influence. Forest vegetation types are considered natural here, although they have been under human influence for centuries or millennia, and specific forest stands can be considered semi-natural or even anthropogenic. Some types of grassland or scrub may occur naturally at some sites, while their formation at other sites has been caused by human management. Such vegetation types are classified into more than one category.

Categories:

• Natural vegetation has developed without human intervention and has not been severely disturbed by humans for a long time; managed forests and old plantations of site-native trees are also included, provided that the composition of their tree, shrub and herb layers corresponds to natural forests

• Semi-natural vegetation develops from natural vegetation as a result of long-term and regular management by humans, e.g., mowing, grazing or burning; such activities have altered vegetation structure and species composition that differ from natural vegetation; vegetation consists mainly of native species that regenerate without direct human intervention; subcategories include:
• Meadow – regularly or irregularly mown grasslands
• Pasture – regularly or occasionally grazed grasslands or scrub but not grazed forests (except for the open patches in wooded pastures that are included here)
• Burned – irregularly burned vegetation, especially scrub
• Disturbed, unmanaged – vegetation at sites that had been disturbed and altered by human activities (e.g., quarries, sod removal sites, military activities, spoil heaps and forest clearings) and then left unmanaged, resulting in secondary succession
• Anthropogenic vegetation occurs in habitats created by human activities and intensively managed or disturbed by humans; alien species are common and may dominate in some types. Subcategories include:
• Weed – weed vegetation on arable and other cultivated lands
• Ruderal – vegetation at uncultivated sites that are frequently or were recently disturbed by human activities
• Neophyte-dominated – woody and herbaceous vegetation dominated by neophytes, either planted or spontaneously established

Data source and citation

Preislerová, Z., Marcenò, C., Loidi, J., Bonari, G., Borovyk, D., Gavilán, R.G., … Chytrý, M. (2024) Structural, ecological and biogeographical attributes of European vegetation alliances. Applied Vegetation Science, 27, e12766. Available at: https://doi.org/10.1111/avsc.12766
Version 2024-02-01, https://zenodo.org/records/10563021 .