23G1
Silver lime (Tilia tomentosa) woods
Relationships with habitat classifications. EUNIS: G1.7C41 Silver lime woods; PAL. CLASS.: 41.841 Silver lime woods; HD 92/43: 91Z0 Moesian Silver lime woods; Bondev (1991): 68 Silver lime (Tilieta tomentosae) forests, partly of secondary origin, 69 Mixed Silver lime (Tilia tomentosa) and Ordinary hornbeam (Carpinus betulus) or Cerris oak (Quercus cerris) forests, partly also with Balkan durmast (Quercus dalechampii), Field maple (Acer campestre) etc., 70 Mixed Silver lime (Tilia tomentosa), Oriental hornbeam (Carpinus orientalis) and Flowering ash (Fraxinus ornus) forests, partly of secondary origin.
Conservation status. BDA, BC, HD.
Category. Endangered [EN – A1 A2 C2 D2 E2 F2 G2 H1 L3].
General characteristics. This habitat encompasses the forests dominated by the Silver lime (Tilia tomentosa). Although the species occurs from Southeast Europe to Southwest Asia it forms coenoses only in South Romania, East Serbia and North Bulgaria. In Bulgaria the Silver lime woods occur mainly in the Danubian Plain and Northeast Bulgaria (Ludogorie region), and in a more limited area in East Forebalkan from 50–60 to 800–1000 m alt. These woods occur in the hilly areas and the foothill on loess and limestone. They cover mainly northern and eastern slopes from 5 to 45°. More rarely, in Ludogorie region, they occur on top of relatively flat elevations. The soils are Kastanik Chernozems, Phaeozems and Luvisols. Their humus horizon is well developed and the humidity is good. There is no typical summer drought in these forests due to the low rate of evaporation and lower temperatures in summer. Their high canopy does not allow the development of a rich herbaceous layer, which additionally would increase the transpiration and soil dryness. Depending on the local conditions these phytocoenoses can be identified as meso-xerophytic or xerophytic ones.
The Silver lime woods are clearly monodominant. Acer campestre, Fraxinus ornus, Quercus cerris, Q. robur also occur in the tree layer apart from the main species – Tilia tomentosa. In some places, mainly in the humid ravines in Ludogorie region, codominants can be Carpinus betulus, Quercus frainetto, Q. petraea agg.Single trees of Acer platanoides, A. pseudoplatanus, A. tataricum, Sambucus nigra, Sorbus torminalis, Tilia cordata also occur. No shrub layer develops in the lime forests. Only Staphylea pinnata, being more resistant to shade, can occur on the slopes of the humid ravines. In some coenoses that occur in more eroded places on limestone, Tilia tomentosa makes mixed communities with Carpinus orientalis. Other shrub species that participate in the lime coenoses are Berberis vulgaris, Cornus mas, C. sanguinea, Corylus avellana, Crataegus monogyna, Ligustrum vulgare, Viburnum lantana. No specific herbaceous layer develops apart from some shadow-resistant species such as Arum maculatum, Buglossoides purpurocaerulea, Dactylis glomerata, Hedera helix, Geum urbanum, Melica uniflora, Melittis melissophyllum, Ruscus aculeatus, Ruscus hypoglossum. A wide distribution of spring ephemeroids is very typical. They can form a short-living herbaceous layer with a projective cover up to 80%. Such are Anemone ranunculoides, Convallaria majalis, Corydalis bulbosa, C. solida, Ficaria verna(= Ranunculus ficaria), Gagea minima, Galanthus elwesii, Helleborus odorus, Isopyrum thalictroides, Lamiastrum galeobdolon, Polygonatum latifolium, Pulmonaria officinalis, Scilla bifolia, Viola odorata, Viola reichenbachiana.Some geophytes (including orchids) that have slightly belated development likeAsperula taurina, Carex pilosa, Cephalanthera damassonium, Lilium martagon, Limodorum abortivum, Platanthera chlorantha, Stellaria holostea, etc. also belong to this group. Most of these species are mesophytes and constitute the connection with order Fagetalia and alliance Carpinion betuli. The phytocoenoses of the Silver lime in the Central Danubian Plain are represented by the endemic association Staphyleo-Tilietum tomentosa. They are remnants from the time when the mesophytic forest vegetation used to be widely distributed (i.e. relic from the Atlantic period of the Holocene) in the lowlands. Natural and anthropogenic factors (climate aridisation, logging, grazing) have caused degradation processes that have lead to the increase of light in the forests and ruderalization of these coenoses. Thanks to its good restoration potential (including from tree shoots), fast growth and good competition potential the Silver lime has preserved and expanded its presence in the natural forests in which probably different oak species used to be co-dominants in the past.
Characteristic taxa.
- Vascular plants: Acer campestre, A. platanoides, A. pseudoplatanus, A. tataricum, Anemone ranunculoides, Aremonia agrimonoides, Arum maculatum, Asperula taurina, Berberis vulgaris, Buglossoides purpurocaerulea, Carex digitata, C. pilosa, Carpinus betulus, C. orientalis, Cephalanthera damasonium, Convallaria majalis, Cornus mas, C. sanguinea, Corydalis bulbosa, C. solida, Corylus avellana, Crataegus monogyna, Dactylis glomerata, Euphorbia amygdaloides, E. polychroma, Ficaria verna(= Ranunculus ficaria), Fraxinus ornus, Fritillaria orientalis, Gagea lutea, G. minima, Galanthus elwesii, Geum urbanum, Glechoma hirsuta, Hedera helix, Helleborus odorus, Isopyrum thalictroides, Lamiastrum galeobdolon, Ligustrum vulgare, Lilium martagon, Limodorum abortivum, Melica uniflora, Melittis melissophyllum, Mercurialis ovata, Platanthera chlorantha, Polygonatum latifolium, Potentilla micrantha, Pulmonaria officinalis, Quercus cerris, Q. frainetto, Q. petraea agg., Q. robur, Ruscus aculeatus, R. hypoglossum, Sambucus nigra, Scilla bifolia, Sorbus torminalis, Staphylea pinnata, Stellaria holostea, Tilia cordata, T. tomentosa, Viburnum lantana, Viola odorata, V. reichenbachiana.
- Fungi: Macromycetes – Amanita phalloides, Boletus fechtneri, B. luridus, Coprinus picaceus, Cortinarius bulliardii, Creolophus cirrhatus, Daedalea quercina, Dichomitus campestris, Fistulina hepatica, Ganoderma lipsiense, G. lucidum, Gymnopus fusipes, G. peronatus, Haasiella venustissima, Hebeloma radicosum, Helvella atra, Hericium erinaceum, Hohenbuechelia petaloides, Hygrophorus russula, Hymenoscyphus calyculus, H. fructigenus, Lactarius chrysorrheus, L. flavidus, L. insulsus, L. pyrogalus, L. zonarius, Leccinum carpini, L. quercinum, Marasmius rotula, Mutinus caninus, Ptychoverpa bohemica, Polyporus squamosus, P. umbellatus, Russula aurea, R. vesca, Sarcoscypha coccinea, Scleroderma citrinum, Sclerotinia coryli; Micromycetes – Apiognomonia errabunda (on Tilia cordata), Diatrype stigma, Hypospilina pustulata, Microsphaera alphitoides (on Quercus spp.), Hypoxylon fuscum, Peronospora corydalis (on Corydalis spp.), Phyllactinia fraxini (on Fraxinus excelsior), P. guttata (on Acer hyrcanum, Corylus avellana), Plasmopara pygmaea, Urocystis anemones (on Anemone nemorosa), Rhythisma acerinum (on Acer pseudoplatanus), Sawadaea bicornis, Septoria aceris (on A. hyrcanum, A. pseudoplatanus).
Distribution in Bulgaria. Mostly in Forebalkan, Danubian Plain, Northeast Bulgaria (Ludogorie region); up to 800 –1000 m alt.
Conservation importance. The natural Silver lime woods are an endemic habitat in Bulgaria, Romania and Serbia and cover limited areas in these countries. This fact increases the responsibility of Bulgaria for the protection of their distribution within the EU. Some rare and endangered vascular plants also occur: Fritillaria orientalis, Galanthus elwesii, Limodorum abortivum, as well as fungi of conservation importance – Cortinarius bulliardii, Creolophus cirrhatus, Geastrum melanocephalum, Haasiella venustissima, Helvella atra, Hericium erinaceum, Hohenbuechelia petaloides, Hygrophorus russula, Leccinum quercinum, Mutinus caninus, Polyporus umbellatus, Ptychoverpa bohemica. The Lime forests are an important source for the medicinal herb (Flores Tiliae) and a resource for bee keeping. They also have considerable aesthetic value during the flowering period of the Lime trees.
Threats. Large-scale clear cuttings, overexploitation of the wood, grazing by domestic animals, increase of light quantity, invading of mat-forming grass species, general climate aridisation. Collecting of lime flowers through cutting of big branches and even whole trees also has negative impact.
Conservation measures taken. The habitat is in Annex № 1 of BDA. Some of the Silver lime woods are within protected areas – Russenski Lom, Shumensko Plato and Persina Nature Parks, Karakuz Protected Site and sites of the European Ecological Network NATURA 2000. In some of the lime forests selective forestry systems for management are being applied. Plantations of Silver lime also have been established.
Conservation measures needed. Floristic and phytocoenostic studies, wider application of the selective forestry systems that are in accordance with the principles for sustainable management of the biological resources; restoration activities; mapping and monitoring of the most preserved and vulnerable phytocoenoses of Silver lime and their proclamation as protected areas.
References. Kalmukov 1987; Tzonev 2003.
Author: Rossen Tzonev
