video

08E1

E. Herbaceous communities and communities of lichens and mosses

Western-Pontic petrophytic steppes

Relationships with habitat classifications. EUNIS: E1.2D1 Western Pontic steppes; PAL. CLASS.: 34.9211 Western Pontic thyme steppes, 34.9212 Western Pontic wormwood steppes, 34.9213 Western Pontic feather grass steppes; HD 92/43: 62C0 *Ponto-Sarmatic steppes; Bondev (1991): Xerothermal grass communities with a prevalence of Dichantieta ischemi, Poaeta bulbosae, Poaeta cocinnae, Chrysopogoneta grylli and Ephemereta.

Conservation status. BDA, HD, BC.

Category. Endangered [EN - A1, 2 B1 C3 D2 E2 F2 G2 H3 I].

General characteristics. This habitat type encompasses various petrophytic calcicole plant communities belonging to the alliance Pimpinello-Thymion zigoidii,order Festucetalia valesiacae and class Festuco-Brometea. They are distributed along the North Black Sea coast and in Dobrudzha area, approximately to the North and East of the line connecting Krushari village, Dobritch town, and Kranevo village. The steppe coenoses that are preserved in this region are strongly fragmented. They occur in places with limestone outcrops, mainly on the slopes of dry river valleys, in areas with landslides and earth creeps and on the large, stony parts of Dobrudhza plateau (areas called “kairyatzi”) bordering the Black Sea coast. The species composition of these communities is very diverse with a prevalence of different mat-forming grasses, semi-shrubs, ephemeres, and ephemeroids. This is a result of the entering into the composition of these communities of sub-Mediterranean and Mediterranean geoelements during Holocene. This process has contributed to their phrygana-like appearance. These steppes can be regarded as a southernmost variety of the Pontic steppes occurring to the North of the Black Sea, but characterized by the presence of a considerable number of Mediterranean and regional endemic geoelements. The Black Sea has a milding effect on the continental-Mediterranean climate in the area. The annual precipitation of 450 mm/year is among the lowest values in the country, and is accompanied by lack of snow cover and surface-running waters.

On the basis of the different bed rockm ecological characteristics and floristic  structure two major habitat subtypes can be distinguished that are related to different plant associations:

1. Western-pontic Artemisia steppes (association Alysso caliacrae-Artemisietum lerchianae).

These communities occur on loose Miocene (Sarmatian) limestone and clay between Balchik and Kavarna towns. They cover small areas on the eastern and southern slopes of 4–5 m high mounds on the steep slopes of landslide terraces facing the sea. High diversity of the fossil fauna (Cardium balcicense, C. kolesnikovi kavarnense, Mactra bulgariaca, M. caspia, etc.) is typical for the organogenic marls on which the steppe vegetation develops. Semiruderal coenoses and scrub with Jasminum fruticans, Paliurus spina-chrsiti, Ulmus minor, etc. develop in more humid places and on the northern slopes of the mounds. The steppe communities are dominated by Agropyron brandzae, Artemisia lerchiana, Aster oleifolius, Echinops ritro, Festuca valesiaca, Jurinea stoechadifolia, Kochia prostrata, Pimpinella tragium subsp. titanophila, Teucrium polium, Thymus zygioides. Additionally, a number of rare, endangered, endemic and sub-endemic taxa like Alyssum caliacrae, Astragalus glaucus, A. spruneri, A. vesicarius subsp. albidus, Ephedra distachya, Goniolimon besseranum, Hedysarum tauricum, Linum tauricum subsp. tauricum, Matthiola odoratissima, Nepeta parviflora occur. Communities dominated by Camphorosma monspeliaca and Brassica elongata, are typical for the steep, saline marls on Chirakman Cape near Kavarna town. They represent an independent sub-association within the described association. These steppe communities have a high level of endemism in Bulgaria and are very vulnerable.

2. Western-pontic Stipa and Thymus steppes (association Paeonio tenufoliae-Koelerietum brevis).

Steppe communities in flat terrains with Calcic Chernozems and Rendzic Leptosols developed to a different degree on Sarmatian limestone at the ridge of Dobrudzha plateau. They occur on the plateau areas (called “kairyatzi’) along the Black Sea coast near Bozhuretz village, Kavarna town, Balgarevo village (incl. Kaliakra Cape and Bolata locality), Sveti Nikola, Kamen Bryag and Tyulenovo villages, as well as on the slopes of the dry valleys in the heart of Dobrudzha area: Vidno, Irechek, Bilo, Vaklino, Bezhanovo, Satmboliiski and other villages. These steppe coenoses are autochthonous, but in many places their species composition is considerably changed due to grazing. The steppes in the area of Kaliakra Cape and Bolata locality are closest to the primary stage, the floristic composition of which are mat-forming grasses such as Festuca valesiaca, Koeleria brevis, Stipa lessingiana. In most places, due to grazing, the participation of Stipa lessingiana is reduced in favour of Festuca valesiaca. The dominance of semi-shrubs (Artemisia pedemontana, Chamaecytisus jankae, Euphorbia myrsinites, E.nicaeensissubsp.cadrilateri, Rhodax canus, Satureja coerulea, Scutellaria orientalis subsp. pinnatifida, Tanacetum millefolium,Thymus zygioides) is typical. They are accompanied by many Mediterranean or endemic terrophytes (Adonis flammea, Cerastium bulgaricum, Helianthemum salicifolium, Scandix australis, Trigonella gladiata, Valerianella pumila, Ziziphora capitata). The variegated spring aspect of different bulbous and rhizomatous terrophytes is typical for the area – Adonis vernalis, A. volgensis, Bellevalia ciliata, Iris pumila, Paeonia tenuifolia. Close to the urban areas, as a result of pasture degression, spiny and poisonous ruderal species occur such as Carduus acanthoides, Carthamus lanatus, Eryngium campestre, Marrubium peregrinum. In the periphery of the ancient settlements (Kaliakra and Yailata), mainly as a result of soil nitriphication, secondary coenoses of Asphodeline lutea and Paeonia peregrina have occurred. In the heart of Dobrudzha plateau, in the dry river valleys, on richer soils and due to the existence of wood and shrub communities, many, more mesophytic species such as Achillea millefolium, Cotinus coggygria, Crataegus monogyna, Fragaria viridis, Fraxinus ornus, Origanum vulgare, Poa angustifolia, Teucrium chamaedrys occur.

Characteristic taxa.

Distribution in Bulgaria. Black Sea coast – between Balchik town and Tylenovo village, and to the West of Dobrich town in the heart of Dobrudzha plateau.

Conservation importance. Endangered habitat in Bulgaria that covers restricted areas and was subjected to various long-lasting negative impacts.It is very important for the preservation of many rare, endangered and protected plants, some of which are dominants in the steppe coenoses: Adonis volgensis, Artemisia lerchiana, A. pedemontana, Avena eriantha, Bellevalia ciliata, Centaurea caliacrae,Ephedra distachya, Goniolimon besseranum,G. collinum, Iris pumila, Koeleria brevis, Limonium latifolium, Matthiola odoratissima,Nepeta parviflora,Paeonia tenuifolia, Ruta graveolens, Scandix australis, Stipa lessingiana. The fungi Tulostoma volvulatum is of conservation importance and is also registered.

Threats. The larger part of these steppes in Dobrudzha area were destroyed in ancient times. Grazing has had a negative impact that caused changes in their species composition. The exploitation of limestone and marl, forest planting and natural land slides and earth-creeps in the region have also had considerable impact. In the recent years tourism and urbanization (golf playground construction, holiday complexes, motor racing, etc.) has also had a very strong negative impact. The, wind electric power parks have negative impact in the second  habitat subtype described above.

Conservation measures taken. The habitat is in Annex № 1 of the national Biodiversity Act. Parts of the localities are within the borders of protected areas: Kaliakra Strict Nature Reserve, Yalata Protected Site, etc. Most of the steppe coenoses of this type are within the borders of protected sites of the European Ecological Network NATURA 2000 in Bulgaria.

Conservation measures needed. Termination of the construction of tourist and sports complexes and wind electric power parks in this habitat, monitoring of the phytocoenoses, and reconstruction of disturbed and destroyed localities.

References. Davidov 1914; Tzonev et al. 2006; Velchev 2002.

Authors: Rossen Tzonev, Veska Roussakova, Marius Dimitrov


Western-Pontic petrophytic steppes (distribution map)