Title
Cantabrian-Euscaldian mixed oak-ash forests (Fraxinus excelsior, Quercus robur, Quercus petraea, Tilia platyphyllos, Fagus sylvatica) with Polystichum setiferum, Pulmonaria affinis, Stellaria holostea, Potentilla sterilis
Geographical distribution
Country/territory
Spain: from Asturia over Cantabria as far as to the Basque country, Navarra; France: Basque country, Béarn
area frequency
6 polygons.
Scientific names of main plant communities and their most common synonyms (with author citation)
Spain: a) Polysticho setiferi-Fraxinetum excelsioris (R. Tüxen & E. Oberdorfer 1958) Rivas-Martínez & C. Navarro 1982; b) Crataego laevigatae-Quercetum roboris S. Rivas-Martínez & J. Loidi 1988; France: Pulmonario affini-Quercetum roboris (Gruber 1990) Rameau 1994 (largely corresponds to a)).
Structural feature of the main community(ies) (layers, life-forms, etc.)
In the closed tree layer pedunculate oak and ash predominate with variable proportions. The species-rich and in part evergreen shrub layer is usually dominated by Corylus avellana, Crataegus monogyna, Cornus sanguinea and Ilex aquifolium. Evergreen Mediterranean species are frequently added, and a lower shrub layer is developed with mainly winter and evergreen trees. Lianas play an important role, particularly Hedera helix, Tamus communis, Lonicera periclymenum and Rubia peregrina. The herb layer is usually luxuriantly developed, species-rich and contains many hemicryptophytes as well as large-leaved ferns. The moss layer on the other hand is usually weakly developed.
Dominant and most frequent species in different layers
Tree layer
Quercus robur, Fraxinus excelsior, locally admixed in differentiating portions Acer campestre, Ulmus glabra, Tilia platyphyllos, Castanea sativa, Fagus sylvatica, occasionally Quercus petraea, Quercus pyrenaica, Acer pseudoplatanus, Carpinus betulus (only in the eastern part), Acer opalus, Quercus ilex, Ulmus minor
Shrub layer
Corylus avellana, Crataegus monogyna, Cornus sanguinea, Ilex aquifolium, Euonymus europaea, further Ligustrum vulgare, Prunus avium, Prunus spinosa, Crataegus laevigata, Sambucus nigra, Salix atrocinerea, Viburnum opulus, locally Rhamnus cathartica, Lonicera xylosteum, Laurus nobilis, Rhamnus alaternus; lower shrub layer: Ruscus aculeatus, Rubus ulmifolius, Daphne laureola, Rubus fruticosus agg., locally Rosa arvensis, Rosa sempervirens
Lianas
Hedera helix, Lonicera periclymenum, Tamus communis, Rubia peregrina (incl. subsp. longifolia), Smilax aspera, Clematis vitalba
Herb layer
Brachypodium sylvaticum, Primula acaulis, Conopodium majus, Sanicula europaea, Helleborus viridis subsp. occidentalis, Isopyrum thalictroides, Brachypodium pinnatum subsp. rupestre, Carex sylvatica, Ceratocapnos claviculata, Pulmonaria affinis, Pulmonaria longifolia, Euphorbia amygdaloides, Euphorbia dulcis, Hepatica nobilis, Melica uniflora, Mercurialis perennis, Potentilla sterilis, Viola reichenbachiana, Circaea lutetiana, Ranunculus ficaria, Ranunculus nemorosus, Stellaria holostea, Polygonatum multiflorum, Geranium robertianum, Arum italicum, Symphytum tuberosum, Iris foetidissima, Carex umbrosa and further species of the Fagetalia; fern aspect in summer: Polystichum setiferum, Dryopteris affinis (incl. subsp. borreri), Athyrium filix-femina, Asplenium scolopendrium, Dryopteris filix-mas, Pteridium aquilinum, Blechnum spicant
Moss layer (incl. lichens)
Eurhynchium striatum, Thuidium tamariscinum, Fissidens taxifolius, Plagiomnium undulatum
Diagnostically important species
a, b) Quercus robur, Fraxinus excelsior, Corylus avellana, Crataegus monogyna, Cornus sanguinea; Pulmonaria longifolia, Brachypodium sylvaticum, Carex sylvatica, Stellaria holostea, Euphorbia amygdaloides, Euphorbia dulcis, Helleborus viridis subsp. occidentalis, Tamus communis, Smilax aspera, Polystichum setiferum, Primula acaulis, Asplenium scolopendrium; additionally for a) Quercus ilex; Laurus nobilis, Rosa sempervirens; Ruscus aculeatus, Rubia peregrina subsp. longifolia; Arum italicum; additionally for b) Quercus petraea, Acer opalus; Crataegus laevigata; Festuca heterophylla, Lathyrus niger, Senecio adonidifolius
Ecological variants
Fern-rich form on debris slopes with Asplenium scolopendrium and Asplenium adiantum-nigrum, as well as with Umbilicus rupestris, Lamium maculatum and Aquilegia vulgaris. In valleys the community ascends to 300-400 m and is then more beech enriched. Above 400-500 m it transforms into beech forest (Scillo lilio-hyacinthus-Fagetum F138 etc.).
Geographical variants (geogr. differential species)
a) a) widespread (typical) oceanic unit on neutral to moderately acidic soils in the colline-submontane belts of northern Cantabria, Asturia and Basque:Forms:a1) with dominating Fraxinus excelsior in the area around Oviedo;a2) with Acer campestre, Lithospermum purpurocaeruleum and Quercus ilex from Santander to the Bay of Biscay;a3) an east Euscaldian form with Carpinus betulus on lime-rich sites (marble in the Bidasoa basin);b) montane-submontane distributed unit in the interior and on the southern side of the Cantabrian mountains as well as the western Pyrenees (Navarra) on deep soils with dry summers, i.e. of a Mediterranean tendency:b1) typical form with Quercus robur, Q. x coutinhoi, Crataegus laevigata;b2) form with Ulmus minor in river valleys and basins adjacent to Quercus pubescens, Q. faginea and Q. ilex subsp. rotundifolia forests;b3) form with Quercus petraea and more continentally distributed species such as Acer opalus, Sorbus aria, Lathyrus niger, Senecio adonidifolius.
Natural accompanying vegetation (most important units in complex with the name giving mapping unit, scientific names)
On enclaves with sandy flysch, oligotrophic oak forests occur with Quercus pyrenaica (Androsaemo-Quercetum, F15). Along watercourses alder-ash forest (Hyperico androsaemi-Alnetum) with Hypericum androsaemum, Carex pendula, Carex remota, Carex strigosa, Equisetum temateia, Elymus caninus and further representatives of the Alno-Ulmion. These forests are closely associated with mapping unit F33. In ravines on seepage sites there are alder forests with Chrysosplenium oppositifolium, Saxifraga hirsuta, Hypericum androsaemum, Cardamine raphanifolia, Pinguicula grandiflora, Sibthorpia europaea.
Adjoining climax and permanent vegetation (with numbers of mapping units)
acidophilous oak and mixed oak forests (F14, F15, F24), species-poor beech forests (F81, F98), species-rich beech forests (F136, F137, F138), downy oak forests (G41), Quercus faginea-forests (G72, G73), Quercus ilex subsp. rotundifolia-forests (J8), holm oak forests (J13), dune vegetation (P8).
Land use, substitute communities
forestry (substitute communities, plantations of economic tree-species, scrub)
Afforestation of heaths with Pinus pinaster, Pinus radiata, Pinus sylvestris, Pinus nigra, Larix kaempferi or various American conifers. The degradation of the forest by traditional grazing and forestry has led to a dense “Dornbusch” (thorn-bush) vegetation (Rhamno-Crataegetum laevigatae) alternating with productive pasture land and meadows. Oligotrophic heath scrub (Daboecienion cantabricae) with Ulex gallii, Erica vagans, Daboecia cantabrica, Lithodora diffusa is promoted by acidification and frequent burning off. Forest mantles and gorse scrub: Rubo ulmifolii-Tametum communis, Ulici europaei-Genistetum occidentalis.
grassland (meadows, pastures, herb-rich communities)
Agricultural landscape with bocage (hedge) pastures (Merendero-Cynosuretum cristati, Lino-Cynosuretum cristati) and grazed heaths (Calluno Genistion pilosae); locally also meadows.
arable land (characteristic weed communities)
Frequent cultivation of corn and fodder plants, after which potatoes, cereal (wheat or rye), grapes and fruits find favour. Laurel (Laurus nobilis) and fig (Ficus carica), that were introduced long ago, have now become completely naturalised.
settlements (typical ruderal vegetation)
Urtico-Sambucetum ebuli, Picrido-Melilotetum albi.
Site conditions of the mapping unit
Landscape type, geomorphology
Coastal, mildly undulating hilly country and lower uplands, wide valleys and basins in the mountains
Altitudinal belt and/or altitudinal range
a) colline-submontane, up to ca. 450 m;
b) montane-submontane, 500-800 (1000) m
Geology (bedrock)
flysch, limestone (Cretaceous), Jurassic
soil type, also the depth of fine textured earth (soil), stone content; (international nomenclature)
base-rich, mostly deep brown soils and parabrown soils, mostly pseudogleyed or gleyed, pseudogley; (humic, eutric, calcic and gleyic cambisols; gleyic luvisols; eutric planosols)
soil texture
loam to clayey loam, locally clay
soil moisture, water balance
fresh to periodically moist; locally moist or moderately dry
soil reaction
weakly acidic, neutral
soil fertility
mesotrophic to eutrophic
Climate incl. local climate
climate type (following Walter & Lieth)
V(VI), (IV)
average annual temperature
a) 10-15 EC; b) 8-12 EC
average annual precipitation
a) 900-1600 mm; b) 1000-1400 mm
average temperature of the warmest month
July 18-20 EC
average temperature of the coldest month
January 2-6 EC
local climate or other climatic peculiarities
a) warm-humid climate; the summerly dryness increases towards the Asturian west and thus the mesophytic ash forest (Polysticho setiferi-Fraxinetum excelsioris) disappears. An average precipitation of 150 mm from June to August seems to be climatically limitating, especially an average July-precipitation of 35 mm; b) higher altitudes further in the centre of the country with a summer-warm, more continental climate.
Importance for nature protection
Present state and development trend of natural vegetation (degree of endangerment)
Remnants of these oak-ash forests are mainly in communal or private hands. They are traditionally used as low or middle forest, sometimes being pollarded and grazed. Semi-natural forest remnants are rare and exist as only small-area incidences; they are also isolated from one another and their stocks are endangered.
endangered communities, species worthy of protection in natural vegetation
The formations with Carpinus betulus show the southwestern distibutional limit of this species. All nearly-natural stands of these forest types as well as some substitute communities are especially worthy of protection due to their rarity and small-scaled occurrence as well as for the rich forest flora.
causes of endangerment
Low and middle forest use, grazing, haymaking, clearing for agricultural use, transformation into exotic tree plantations.
required measures for protection and restitution
Preservation of the remaining stands, strict protection of representative semi-natural forest stands, regeneration of natural forests, networking of the forest remnants. Continuation of traditional usage forms in a number of selected examples.
Localities of representative stands (loci typici) with state of protection
of the natural vegetation
Spain: a) Covadonga (Asturia), depression of Bidasoa (Basque country) and further; b) lowlands in Navarra (near Burguete, Lecumberri, Ulzama) as well as Alava, Izarra, Barrundia.
of characteristic substitute communities worthy of protection
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Most important references (author, year)
Braun-Blanquet 1967a; Díaz González & Fernández Prieto 1987; Díaz González & Fernández Prieto 1994a; Díaz González & Fernández Prieto 1994b; Jovet & Dupias 1969; Loidi Arregui 1987; Loidi Arregui & Bascones 1995; Navarro Aranda 1982; Navarro Sánchez 1989; Rivas-Martínez 1987; Rivas-Martínez, Bascones, Díaz González, Fernández-González & Loidi Arregui 1991a; Rivas-Martínez, Díaz González, Fernández Prieto, Loidi Arregui & Penas Merino 1984; Rivas-Martínez & Loidi Arregui 1988; Rivas-Martínez, Loidi Arregui, Cantó, Sancho & Sánchez-Mata 1985; Timbal 1988; Tüxen & Oberdorfer 1958; Vigo Bonada 1968
Compiled by
J.R. Cross and U. Bohn based on documents by A. Noirfalise; V. Voggenreiter based on documents by Rivas-Martínez; A. Penas Merino and L. Herrero Cembranos, J. Loidi
