Ravine woodland

One striking situation in Europe where beech and oaks can be out-competed by such fast-growing trees as Fraxinus excelsior, Acer pseudoplatanus, A. platanoides, Ulmus glabra and, Tilia platyphyllos and Tilia cordata is on the nutrient-rich soils that accumulate in the humid micro-climate of shady slopes and ravines. Here, with downwash and percolation of ground water, the brown earth soils can be deep and moist, but usually they are free-draining and show a brisk turnover of nutrients and mull humus. Typically, such situations are associated with hard, base-rich, though not always calcareous, rocks and they occur widely throughout steep-sided immature river valleys of the foothills, sub-montane and high mountain belt right across Europe. The terrain is typically complex and rocky, with a heterogenous soil cover and the structure of these woodlands has been vividly described as ‘impetuous’. The distinctive kind of terrain necessary to sustain this habitat means that through Europe, these woodlands have a basic floristic and structural similarity, though variations in regional climate support distinctive contingents of associates with more Continental, Boreal, Alpine, Mediterranean or Atlantic affinities. There is also some floristic variation according to whether the habitat is on very moist colluvium, is humid primarily because of shade or gets some warmth at ravine tops or by virtue of being in more southerly latitudes. More generally across the range, Quercus robur, Q. petraea and Fagus sylvatica can make a minority contribution to the canopy along with Carpinus betulus and Sorbus aucuparia. Through France, Germany, Austria and Switzerland, there is a tendency for more montane stands to be dominated by Acer platanoides, A. pseudoplatanus or A. opalus while those at lower altitudes have abundant lime (Tilia spp.). More particularly, Tilia platyphyllos is the lime more confined to ravine forests while T. cordata is more widely characteristic of G1.Aa Mesic deciduous woodland. The difficult terrain which has protected against exploitation of these woodlands and the extraordinary longevity of both limes means that these ravines can harbour some of the most ancient and majestic trees of Europe.

In the shrub layer Sambucus nigra is characteristic along with Corylus avellana, while the field layer is dominated by luxuriant nitrophilous herbs such as Urtica diocia, Aegopodium podagraria and Impatiens noli-tangere, moisture-loving vernal plants like Allium ursinum and, on the typically base-rich soils, Mercurialis perennis, Geranium robertiamum, Brachypodium sylvaticum and Circaea lutetiana. More especially distinctive are Lunaria rediviva, Helleborus viridis, Aruncus dioicus, Actaea spicata, Aconitum vulparia, Corydalis cava, Equisetum hiemale, Polygonatum verticillatum, and Aconitum paniculatum. Sometimes Allium ursinum can dominate the herb layer. Then, reflecting the high humidity, there are often abundant ferns such as Phyllitis scolopendrium, Polystichum aculeatum. P. setiferum and Gymnocarpium robertianum and bulky mosses thrive on the bare ground exposed by the rapid breakdown of herbage and litter at the close of the growing season. Lichens can also be well developed with species such as Lobaria pulmonaria or Gyalecta ulmi.

In the Atlantic zone, where the climate is more generally cool and humid, woodlands of this kind are less confined to ravines, particularly where base-rich rocks are extensively exposed. Also, approaching or beyond the limits of Acer pseudoplatanus, A. platanoides and even the limes, as in north-west Great Britain, there is a tendency for stands to be dominated by Fraxinus excelsior and Ulmus glabra, or even Corylus avellana in situations exposed to humid oceanic winds. Similar vegetation reported from southern Scandinavia also falls within this habitat type. Northern montane plants such as Prunus padus, Ribes saxatilis, Actaea spicata, Trollium europaeus, Crepis paludosa, Cirsium helenioides and Geranium sylvaticum can here give this habitat a Boreal feel. Towards southern Europe and particularly in sunny ravines at lower altitudes in Czechia, Hungary, Romania and the Pyrenees, there is a thermophilous contingent in this habitat including Cotoneaster integerrimus, Sesleria caerulea, Athericum ramosum, Vincetoxicum hirundinaria and other species more typical of the G1.7a and G1.7b thermophilous woodlands. South of these latitudes, the habitat occurs locally in the Italian pre-Alps and reaches its southern limit in the humid north-facing ravines of the Appennines. In ravines among G3.1c Mediterranean mountain Abies woodland in such situations, there can be occasional Abies alba among the canopy trees.

Indicators of quality:

• No forest exploitation

• Maintenance of the complex ravine topography, micoclimatic conditions and woodland structure

• Sufficient structural diversity/ complexity (semi)natural age structure or completeness of layers

• Sufficient proportion of historically old (ancient) woodland with high species diversity

• Presence of old trees and a variety of dead wood (lying and standing) and the associated flora, fauna and fungi

• Rich and luxuriant field and ground layers protected by continuous canopy and locally high humidity with typical flora and fauna composition of the region

• Absence of non-native tree species and absence of invasive aliens in all layers (fauna, flora)

• No signs of eutrophication or pollution, absence of nitrophilous adventives

• No fragmentation and isolation (no major disruptions in the ravine forests with coniferous plantations).

Main

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats