28G1
Mixed forests on screes, steep slopes and mountain ravines
Relationships with habitat classifications. EUNIS: G1.A4 Ravine and slope woodland; PAL. CLASS.: 41.4 Mixed ravine and slope forests; HD 92/43: 9180 *Tilio-Acerion forests of slopes, screes and ravines.
Conservation status. BDA, BC, HD.
Category. Endangered [EN – A1, 2 B1 C2 D3 E2 F2 G2 H2 I J L2].
General characteristics. The habitat encompasses shady and humid mixed deciduous forests of primary or secondary origin with various species in the tree layer but always with species of Acer, Tilia, and Fraxinus. Different species can be dominants. The polydominant phytocoenoses cover more or less steep rocky slopes, screes and uneven coluvial deposits mostly on limestone. The herbaceous layer consists of species typical for the beech forests. They have survived in areas where the dominance of the beech has been impossible. Syntaxonomically these forests belong to the alliance Tilio-Acerion that includes the sub-alliances Lunario-Acerenion and Tilio-Acerenion. The centre of distribution of this habitat is continental Europe but it also widely occurs from Scandinavia to the Pyrenees and Italy. Bulgaria is in the southwestern part of its area of distribution.
Typically, in Europe, the communities of this type occur on silicate, while in Bulgaria it occurs mainly on limestone. They occupy steep river valleys in the low mountains, foothills and mountain belts of all Europe. Small changes in the conditions, the substrates or the humidity can cause transition to the beech forests (with the increase of the humidity to Cephalantero-Fagenion, Luzulo-Fagenion or Asperulo-Fagetum) or to the thermophilic oak forests when the conditions are more xerophytic. This habitat varies ecologically and the tree composition is different. The floristic differences are due to the differences in the slope, exposure and substrate in the localities. The floristic composition is diverse but most frequently the following herbaceous species occur: Allium ursinum, Dryopteris spp., Galium aparine, Geranium robertianum, Geum urbanum, Mercurialis perennis, Phyllitis scolopendrium, Polystichum setiferum, Urtica dioica etc.
There are two sub-types of this habitat:
1. Hygrophilic forests in valleys and on slopes (sub-alliance Lunario-Acerenion). In the humid and shady places develop hygrophilic and skiophilic vegetation from the sub-alliance Lunario-Acerenion with the participation of Acer hyrcanum, A. pseudoplatanus, Actaea spicata, Allium ursinum, Fraxinus excelsior, Lunaria rediviva, Mercurialis perennis, Ulmus glabra etc.
An endemic and relic for the Balkan Peninsula variation of this habitat has been found in Bulgaria. It is dominated by centurial trees of Acer heldreichii and the participation of single trees of Acer pseudoplatanus and Fraxinus excelsior (Elena-Tvarditsa part of the Central Balkan Range).
2. Xerophilic forests in valleys and on slopes (sub-alliance Tilio-Acerenion). On the dry and sunny screes develop xero-thermophilic vegetation from the sub-alliance Tilio-Acerenion with the participation of Tilia cordata, T. platyphyllos, Carpinus betulus, Corylus avellana, Quercus spp., Sesleria varia, Anemone nemorosa, Primula veris, Corydalis spp.,etc. In Stara Reka Strict Nature Reserve, Central Balkan Range, at 860 m alt. a coenoses has been described that includes all tree and most of the herbaceous species that are typical for both sub-alliances. This proves that mixed varieties between the two subtypes of this habitat also occur.
Characteristic taxa.
- Vascular plants: Acer heldreichii, A. hyrcanum, A. platanoides, A. pseudoplatanus, Actaea spicata, Allium ursinum, Anemone nemorosa, Anthriscus sylvestris, Arum maculatum, Asarum europaeum, Asplenium adiantum-nigrum, Athyrium filix-femina, Brachypodium sylvaticum, Campanula rapunculoides, Dentaria bulbifera (= Cardamine bulbifera), Carpinus betulus, Circaea lutetiana, Corydalis spp., Corylus avellana, Cystopteris fragilis, Dryopteris filix-mas, Epilobium montanum, Euonymus latifolius, Fagus sylvatica, Fraxinus excelsior, Galium aparine, G. odoratum, Geranium macrorrhizum, G. robertianum, Geum urbanum, Glechoma hederifolia, Hieracium murorum, Impatiens noli-tangere, Lamiastrum galeobdolon, Lunaria rediviva, Luzula luzuloides, Mercurialis perennis, Milium effusum, Mycelis muralis, Oxalis acetosella,Phyllitis scolopendrium, Polygonatum odoratum, Polypodium vulgare, Polystichum setiferum, Prenanthes purpurea, Primula veris, Pulmonaria officinalis, Quercus spp., Ribes alpinum, Sambucus nigra, Saxifraga rotundifolia, Sedum maximum, Senecio nemorensis, Stellaria nemorum, Tilia cordata, T. platyphyllos, Ulmus glabra, Urtica dioica, Veronica urticifolia,Bryophyta,etc.
- Fungi and animals: Macromycetes – Armillaria mellea, Auricularia mesenterica, Boletus aestivalis, B. chrysenteron, B. luridus, B. subtomentosus, Cantharellus cibarius, Craterellus cornucopioides, Creolophus cirrhatus, Daedalea quercina, Ganoderma lucidum, Gymnopus peronatus, Hymenoscyphus fructigenus, Inonotus nidus-pici, Lactarius circellatus, L. pyrogalus, Leccinum carpini, Marasmiellus ramealis, Marasmius epiphyllus, M. rotula, Merulius tremellosus, Mycena inclinata, Peniophora lycii, P. quercina, Pleurotus dryinus, P. ostreatus, Polyporus squamosus, P. tuberaster, P. varius, Russula foetens, Stereum gausapatum, Xylaria hypoxylon; Micromycetes – Apiognomonia errabunda (on Tilia cordata), Apioplagiostoma carpinicolum, Gnomoniella carpinea, Phyllactinia guttata, Plagiostoma arnstadtiense (on Carpinus betulus), Ascochyta ambrosiana (on Hedera helix), Diatrype stigma, Hyaloperonospora parasitica (on Dentaria bulbifera), Hypospilina pustulata, Microsphaera alphitoides (on Quercus spp.), Rhytisma acerinum, Sawadaea bicornis (on Acer campestre), Septoria euphorbiae (on Euphorbia amygdaloides), S. quercicola (on Quercus petraea).
- Animals – Chiroptera: Barbastella barbastellus, Eptesicus serotinus, Hypsugo savii, Myotis blythii, M. capaccinii, M. myotis, M. mystacinus, Nyctalus noctula, Pipistrellus pipistrellus, Rhinolophus ferrumequinum.
Distribution in Bulgaria. Balkan Range, Rhodopi, Rila, Vitosha, Osogovska, Lozenska Mts.(subtype Tilio-Acerenion); probably also in other mountains; at 800–1400 m alt.
Conservation importance. The following vascular plants of conservation importance occur in this habitat: Acer heldreichii, Festuca balcanica, Haberlea rhodopensis, Micromeria frivaldszkyana, Taxus baccata. The fungi species of conservation importance Creolophus cirrhatus also occurs.
Threats. Logging, fires, erosion.
Conservation measures taken. The habitat is included in Annex № 1 of BDA and is of conservation priority. Parts of this habitat are within Sokolna, Byala Reka and Stara Reka Strict Nature Reserves, Vitosha Nature Park, Central Balkan and Rila National Parks, etc. and in sites of the European Ecological Network NATURA 2000.
Conservation measures needed. Scientific studies to establish the distribution and specificities of the habitat in Bulgaria and monitoring of the state of the most representative localities of this habitat.
References. Ganchev 1952, 1961; Gussev et al. 2005b.
Author: Alexander Tashev
