18G1

G. Forests

Steppic woods of Turkey oak (Quercus cerris)

Relationships with habitat classifications. EUNIS: G1.7A1 Euro-Siberian steppe [Quercus] woods; PAL. CLASS.: 41.7A1 Euro-Siberian steppe [Quercus] woods; HD 92/43: 91I0 *Euro-Siberian steppic woods with Quercus spp.; BONDEV (1991): 90 Cerris oak (Querceta cerris) forests, 96 Mixed Cerris oak (Quercus cerris, Q. pubescens, Q. virgiliana forests, 97 Mixed Cerris oak (Quercus cerris and Q. pubescens) forests with undergrowth of Sumach (Cotinus coggygria) partly, e.g. in the Danube plain with a secondary prevalence of Sumach.

Conservation status. BDA, BC, HD.

Category. Endangered [EN – A1, 2 B1 C1 D2 E2 F2 G2 H2 L3].

General characteristics. This habitat type encompasses monodominant forests of Quercus cerris that occur on the loess heights in the northern parts of the Danubian Plain and Ludogorie area, from 100 up to about 400 m alt. The Turkey oak forests cover the top, flat parts of these heights or mainly southern, southwestern and southeastern slopes. Usually, on the eastern and northern  slopes they turn into coenoses of Tilia tomentosa, and in the Ludogorie area – into coenoses of Carpinus betulus and Fraxinus excelsior as well. In the most eroded places these forests turn into scrub of Carpinus orientalis. The loess sediments on which the coenoses of Quercus cerris develop are mainly clayey and this has its impact on the soil. It is heavier and more clayey compared to the soils in the thermophilic mixed forests of Quercus cerris and Q. frainetto. The soils are mainly Chernozems and Phaeozems, and more rarely Luvisols. They are relatively rich and thick but are dry and become even drier in the summer months. The climate is typical continental – high annual temperature amplitudes, summer drought and relatively low annual rain quantity (between 500 and 600 mm).

The monodominant steppic woods of Q. cerris occur mainly to the North of the line connecting the following towns Vidin – Brusartsi – Byala Slatina – Koynare – Letnitsa – Pavlikeni – Opaka – Razgrad – Valchidol – Varna. To the South, in the Forebalkan, the participation of Quercus frainetto increases and gradually the forests become monodominant coenoses of this species. The forests of Quercus cerris originate mainly from shoots but there are mixed forests in which some of the trees have developed from seeds. Most of the trees are between 40 and 60 years old and 8 and 10–20 m high. The canopy varies from 0,6 to 0,9. are also Q. pubescens, Q. frainetto, Q. virgiliana, Q. dalechampii, Q. pedunculiflora, Sorbus domestica, Pyrus pyraster, Ulmus minor, Acer campestre are also relatively frequent in the tree layer apart from Quercus cerris. In some places a second tree layer can be distinguished with Acer tataricum, Carpinus orientalis, Fraxinus ornus, that can be 5–6 m high. However, these species participate most often in the shrub layer. Tilia tomentosa, Carpinus betulus, and Sorbus torminalis occur also in the Ludogorie area, in more humid places (in the ravines). Crataegus monogyna dominates the shrub layer. It is replaced by Cotinus cogyggria when there is more light in the forests, that is often a result of anthropogenic activities (wrongly conducted sanitary logging and grazing) in many places (e.g. Central Danubian Plain). This layer is usually about 1–1,5 m high, but in the lightest places it can reach up to 3–4 m. Other shrub species that occur rather often are Chamaecytisus hirsutus, Cornus mas, C. sanguinea, Euonymus europaeus, E. verrucosus, Prunus spinosa, Rhamnus catharticus, Rosa gallica, and Viburnum lantana.The herbaceous layer includes species that are widely distributed in the oak forest in Bulgaria, but also some species typical for the steppic woods especially in the light forests and scrub. Most frequent are Allium fuscum,Betonica officinalis(= Stachys officinalis), Brachypodium sylvaticum, Buglossoides purpurocaerulea, Bupleurum praealtum, Clinopodium vulgare, Crocus flavus, Dactylis glomerata, Doronicum hungaricum, Festuca heterophylla, Fragaria vesca, Galium pseudaristatum, Geum urbanum, Glechoma hirsuta, Helleborus odorus, Iris sintenisii, I. variegata, Laser trilobum, Lathyrus niger, L. pannonicus, Lychnis coronaria, Muscari tenuiflorum, Peucedanum alsaticum, Sedum maximum, Serratula tinctoria, Tanacetum corymbosum, Teucrium chamaedrys, Verbascum phoeniceum, Viola odorata, and Viscaria vulgaris.

The steppic woods of Quercus cerris constitute a part of the large complex of oak forests in the hilly lowlands and mountain foothills of SE Europe from the alliance Quercion frainetto, although they show some transitional characters and some species are typical for the steppic woods alliance Aceri tatarici-Quercion. Species typical for the latter alliance are Acer tataricum, Doronicum hungaricum, and Lathyrus pannonicus. In the vicinity of Pleven town the forest coenoses belong to the association Cotino-Quercetum cerris, which probably has wider distribution in North Bulgaria.

The steppic woods of Quercus cerris have been subjected to strong anthropogenic pressure such as logging, grazing, fires. Often (especially in the Danubian plain and more rarely in the Ludogorie area) they have very low restoration potential. Additionally the participation of the Sumach and grass species makes this restoration impossible. In many places these forests have been replaced by derivative tree, shrub and herbaceous coenoses – e.g. of Bothriochloa ischaemum(= Dichanthium ischaemum), Carpinus orientalis, Chrysopogon gryllus, Fraxinus ornus.

Characteristic taxa.

Distribution in Bulgaria. North Bulgaria – Danubian Plain and Ludogorie Area, to the North of the line connecting the following towns Vidin – Brusartsi – Byala Slatina – Koynare – Letnitsa – Pavlikeni – Opaka – Razgrad – Valchidol – Varna. Southwards from the Danube, 20–40 km in the Danubian plain and 10–15 km in the Ludogorie area the steppic woods of Quercus cerris are absent. They occur mainly between 100 and 400 m alt.

Conservation importance. These forests are a habitat that is subjected to strong anthropogenic pressure: logging, grazing, fires. Some rare, endangered and protected species of vascular plants like Anemone sylvestris, Chamaecytisus kovacevii, Galium rubioides, Hesperis sylvestris subsp. velenovskyi, and fungi – Amanita caesarea, Clavariadelphus pistillaris, Disciotis venosa, Hygrophorus russula, Tricholoma acerbum, Urnula craterium occur. These forests are the source of some medicinal plants – Crataegus spp., Cotynus coggygria, Teucrium spp., Heleborus odorus, Betonica officinalis, etc.

Threats. Large-scale clear cuttings and illegal logging, over-exploitation of wood mainly for heating, and lack of legal restriction for logging by the private owners of woods. In the last years these processes have caused the destruction of large areas of such forests, particularly in the Ludogorie Area. Other threats are the replacement of the primary forests with plantations of untypical species (Pinus nigra, P. sylvestris, Pseudoacacia spp.), grazing, (mainly goats), fires, forests clearings, climate aridisation that causes the wide invasion of ruderal species, low restoration potential due to natural and anthropogenic factors and some fungal deceases that affect the young branches.

Conservation measures taken. The habitat is in Annex № 1 of BDA and is of conservation priority. These forests are also within sites from the European Ecological Network NATURA 2000, mainly in the Ludogorie area (near Razgrad, Isperich and Dulovo towns).

Conservation measures needed. Legal changes for termination of the clear cuttings, particularly in the private forests. The activities that take place in these forests have to be targeted only at their restoration, including support for the seed reproduction and fighting the fungal diseases on the young branches. Proclamation of some of the representative coenoses as protected areas.

References. Radkov & Minkov 1963; Stoyanov et al. 1955; Rousakova & Tzonev 2003.

Authors: Rossen Tzonev, Georgi Hinkov


Steppic woods of Turkey oak (Quercus cerris) (distribution map)