22F4

F. Shrub communities

Strandzha heaths of Tree heath (Erica arborea)and Common Heather(Calluna vulgaris)

Relationships with habitat classifications. EUNIS: F4.22C Pontic ling heaths; PAL. CLASS.: 31.22C Pontic ling heaths; HD 92/43: 4030 European dry heaths.

Conservation status. BDA, BC, HD.

Category. Endangered [EN – A1, 2 B1 C3 D3 E2 F2 G2 H2 I L1].

General characteristics. The habitat includes mezophilic and xero-mezophilic shrubs of narrow-leaved, evergreen representatives of family Ericaceae, Erica arborea and Calluna vulgaris. They grow in silicate areas in humid seaside conditions on the western slopes of Strandzha Mts. Such communities are typical for the plains and hilly lowlands in West, Central and South-East Europe where the climate is warm and relatively humid (Atlantic, sub-Atlantic and Mediterranean) at the seaside. Throughout their areas of distribution these two species show ecological and phytocoenological plasticity that make possible their parallel distribution and sympatric existence in the coastal and seaside areas of the Black Sea, including Strandzha Mts. In other parts of their distribution E. arborea and C. vulgaris do not form mixed communities; hence, these communities have their characteristic features in the Black Sea region.

On the northern slopes of Strandzha Mts. C. vulgaris and E. arborea most often form monodominant and, more rarely, mixed coenoses. Usually one of the two species prevails depending on the microrelief, soil and microclimatic conditions. They occupy mostly the sunny parts of dry and steep places. The soils are Chromic Cambisols or Alisols, medium-shallow, often stony. The so called “kalunatsi” are more frequently encountered – shrub communities dominated by Calluna vulgaris occurring in the eastern parts of the Bulgarian part of Strandzha Mts., in areas that coincide with the distribution of the Oriental beech. They grow mostly on strongly eroded ground, on the periphery of rare forest communities or invade abandoned arable lands and pastures. Calluna vulgaris is a shrub 20–70 cm high with ascending or erect branches, imbricate, 2–3 mm long, linear leaves and rose flowers. Its shrubs are dense and their projective cover varies between 60% and 70%.The species composition of the community is relatively poor as a result of the dominance of Calluna vulgaris. Most often the small shrubs Cistus incanus and Genista carinalis and the herbaceous species Anthoxanthum aristatum, Carlina vulgaris, Briza maxima, Dorycnium graecum, Hypericum cerastoides, H. montbretii etc. participate. In some places the abundance of Pteridium aquilinum can be very high.

The monodominant heaths of E. arborea are relatively rare and their distribution is limited to the distribution areas of Rhododendron ponticum, mainly near Kosti village, Hodzha peak, Kamenska Barchina, Pazlashko Bardo and Staro Rezovo localities. They occupy the sunniest places with shallow soils, steep and dry places on sandstones. Erica arborea is a shrub or a small tree (in Strandzha Mts. it can reach up to 1,5 m) with brown bark, erect branches, 4–6 mm long, narrow-linear leaves and small white flowers. It makes dense heaths with 60–70% projective cover or rare scrub that covers relatively small areas. The species composition is relatively rich, including the shrubs Cistus incanus (most often and in some case Cytinus clusii), Cistus salvifolius, Genista carinalis, and more rarely Calluna vulgaris. The following perennial herbs also occur: Chrysopogon gryllus, Anthemis tinctoria, Brachypodium pinnatum, Dorycnium graecum, Echium plantagineum, Hypericum cerastoides, H. montbretii, H. perforatum, H. rumelicum, Poa bulbosa, Stachys angustifolia, S. angustifolia, S. thracica,Teucrium chamaedrys, T. polium, and many terrophytes: Aira elegantissima, Anthoxanthum aristatum, Apera spica-venti, Briza maxima, Centaurium maritimum, Crepis setosa, C. zacintha, Cynosurus echinatus, Euphorbia serrulata,Gastridium ventricosum, Linaria pelisseriana, Linum corymbulosum, Lotus angustissimus, Ornithopus compressus, Psilurus incurvus, Teesdalia coronopifolia, Trifolium purpureum, Xolanthes guttatus, Hypochoeris glabra etc. The shrubs of Calluna vulgaris and Erica arborea are usually of secondary origin as a result of degradation (clearings, felling or destruction) of the open forests of Quercus polycarpa and Quercus frainetto where Calluna vulgaris and Erica arborea are in the shrub layer. The restoration of the autochthonous oak forests is possible in some places covered by such coenoses but with very strong erosion.

Characteristic taxa.

Distribution in Bulgaria. Strandzha Mts. – limited areas in its eastern part between the villages of Kosti, Brodilovo, Rezovo and Slivarovoro and to the West and Northeast towards Malko Tarnovo town; northwards from Zvezdets village; between 100 and 500 m alt.

Conservation importance. Together with the dominants Erica arborea and Calluna vulgaris that are rare species protected by the Biodiversity Act the following species are also of conservation importance: Centaurium maritimum, Cistus salvifolius, Cytinus clusii, Echium plantagineum, Stachys thracica etc., as well as the fungus Pisolithus arhizos.

Threats. Succession of the forest coenoses, grazing and afforestation with Pinus nigra.

Conservation measures taken. The habitat is in Annex № 1 of BDA. Representative areas of this habitat are included in Strandzha Nature Park and Pirena Protected Site, Silkosiya, Vitanovo, Uzunbudzhak, Sredoka Strict Nature Reserves. The localities of this habitat type are within sites of the European Ecological Network Natura 2000.

Conservation measures needed. Monitoring and phytocoenological studies as well as management of the grazing within the localities of this habitat outside the borders of the protected areas.

References. Jordanoff 1939; Palashev 1976; Patronov 2004; Stefanov 1924.

Author: Chavdar Gussev


Strandzha heaths of Tree heath (Erica arborea) and Common Heather (Calluna vulgaris) (distribution map)