02E1

E. Herbaceous communities and communities of lichens and mosses

Mountain petrophytic steppes

Relationships with habitat classifications. EUNIS: E1.21 Helleno-Balkan [Satureja montana] steppes; PAL. CLASS.: 34.311 Helleno-Balkan savory steppes; HD 92/43: 62A0 Eastern sub-Mediterranean dry grasslands (Scorzoneretalia villosae); Bondev (1991): 129 Xerothermic grass communities with a prevalence of Dichantieta ischemi, Poaeta bulbosae, Poaeta cocinnae, Chrysopogoneta grylli and Ephemereta.

Conservation status. BDA, BC, HD.

Category. Vulnerable [VU - A1, 2 B2 C1 D E2 F1 G1 H3 I L2].

General characteristics. Diverse petrophyte, calcicole communities, distributed in karst areas with moderate-continental climate in the low mountains and plateaus of West Bulgaria: southern slopes of Vtosha Mts. (Bosneshki karst), Golo Bardo Mts., Konyavska Mts., Zemen and Milevska Mts., southern slopes of West Balkan Range and Ponor plateau, Dragomaski Chepan Mts., Tri Ushi and Mala Planina Mts. Western Bulgarian mountain petrophytic steppes develop on kartsic Triassic and more rarely Jurassic limestone. Open herbaceous and shrub communities develop on the thin soil layer that is preserved in the rock fissures. The prevalence of aromatic semi-shrubs gives a “phryganoid” outlook of these communities. The areas of this habitat type are of various slopes and exposures, but occupy mostly western and southern slopes or tops of elevations with low humidity and well-developed karst relief. The soils, Chromic Cambisols, Lithic Leptosols, Umbric Leptosols, are poor and in some places are almost absent or are interrupted by different in size rock outcrops. The total projective cover of the coenoses varies from 30 to 60–70%. At lower altitudes, on the northern slopes and on the bottom of ponors, where soils are richer and thicker, the number of the semi-shrubs is reduced and caespitose perennial grasses prevail. Major species for these coenoses are Artemisia alba, Hyssopus officinalis, Satureja montana subsp. kitaibelii. The latter is related to the karst areas in West Bulgaria (incl. Forebalkan) and is an indicator of a specific complex of species, known as “Hyssopus” flora. Apart from the small, aromatic semi-shrubs and shrubs many caespitose, perennial grasses participate in these coenoses: Agropyron cristatum, Bothriochloa ischaemum(= Dichanthium ischaemum), Bromus moesiacus, B. riparius, Cleistogenes serotina, Festuca dalmatica, F. valesiaca, Koeleria splendens, Sesleria rigida, Stipa capillata, S. pennata agg. The participation of some xerophytes is typical, mostly Carex humilis but also C. caryophyllea (in some places forming the spring aspect of the habitat) and C. halleriana. Carex humilis is often a co-dominant together with the small aromatic shrubs and semi-shrubs. Many of the perennial species have brightly coloured flowers, participate in mosaic micro-coenoses, and form different aspects when flowering – in some cases up to 5–6 aspects per vegetation season. Included in this list are Achillea clypeolata, Anthyllis montana, A. vulneraria, Bupleurum falcatum, Chamaecytisus pygmaeus, Convolvulus cantabrica, Fumana procumbens, Haplophyllum suaveolens, Hippocrepis comosa, Inula ensifolia, I. oculus-christi, Onosma visianii, Paronychia cephalotes, Potentilla cinerea, Teucrium montanum. A number of ephemerals species belong here: Allium flavum, A. moschatum, Anthericum ramosum, Crocus biflorus, Fritillaria orientalis, Hyacinthella leucophaea, Iris pumila, Muscari botryoides, Sternbergia colchiciflora, Vinca herbacea. Differently from the southern Bulgarian petrophytic steppes, the number of terrophytes in this habitat is lower: Coronilla scorpioides, Trigonella gladiata, T. monspeliaca, Euphorbia taurinensis, Sideritis montana. Grass species are almost absent except for some widely distributed ones like Poa bulbosa. Some relic steppe species occur. Their area of distribution is mainly to the Northeast of Bulgaria thus the Kraiste region is their most southwestern refugium in Europe. Such are the localities of Aster oleifolius, Astragalus pubiflorus (the latter possibly extinct from the region), Paeonia tenuifolia. The specificity of the coenoses of the western Bulgarian petrophytic steppes is due to the participation of many endemic and subendemic taxa. Most of them have their vicariants in the steppe continental regions or have a restricted distribution in W Bulgaria and part of Serbia. The most typical endemics are: Allium cupani, Astragalus wilmottianus, Centaurea chrysolepis, C.immanuelis-loewii, Edraianthus serbicus, Eryngium palmatum, Jurinea tzar-ferdinandii, Tulipa urumoffii. Some of the species, such as Edraianthus serbicus and Jurinea tzar-ferdinandii, play considerable role in the formation of the vegetation cover, especially on eroded areas where they dominate.

The vegetation of the western Bulgarian mountain petrophytic steppes is characterized by a high level of complexity, i.e. alternation of relatively small fragments of different phytocoenoses, depending mostly on the edafic conditions: soil richness, erosion and (to a lower degree) on the exposure and slope of the area. For instance, in places with a better developed soil layer on northern slopes, or in the depressions among rocks, closed, herbaceous steppe communities (Bothriochloa ischaemum(= Dichanthium ischaemum), Chrysopogon gryllus, Festuca dalmatica) alternate with various shrub coenoses (Amygdalus nana, Cotoneaster integerrimus, Prunus spinosa, Rosa pimpinellifolia, Syringa vulgaris). In wetter depressions some more typical species such as Asphodelus albus occur.

Different theories exist on the origins of the western Bulgarian mountain petrophytic steppes. In some areas they have replaced the destroyed forest fragments which still exist on the northern slopes of the karst elevations. Degradation of these forests is caused by fires, intensive grazing and secondary erosion. On the other hand, especially on the southern slopes and dry ridges of the hills, xerothermic herbaceous vegetation was widely distributed, which is proven by the existence of many refugia of relic and endemic species that were not replaced by forests and have survived the Holocene period. Such species are Amygdalus nana, Aster oleifolius, Astragalus pubiflorus, A. wilmottianus, Jurinea tzar-ferdinadii, Paeonia tenuifolia, etc.

Characteristic taxa.

Distribution in Bulgaria. Southern, lower parts of the West Balkan Range (Ponor and Chepan Mts., Ponor plateau, Mala Planina and Tri Ushi Mts.), Kraiste region (Strazha, Karvav Kamak, Golo Bardo, Konyavska, Zemenska and Milevska Mts, etc.), South Vitosha (Bosnek Karst area) and other neighbouring areas between 500 and 1500 m alt.

Conservation importance. Vulnerable habitat subjected to various, long-term negative impacts.It has an important role for the preservation of the localities of many endemic, rare, endangered and protected species. Many of these species participate in the composition of the petrophytic steppe coenoses. Among them, the rarest are Allium cupani, Anemone sylvestris, Astragalus pubiflorus, A. wilmottianus, Daphne cneorum, Edraianthus serbicus, Ferula heuffelii, Fritillaria orientalis, Goniolimon tataricum, Jurinea tzar-ferdinandii, Lathyrus pancicii, Paeonia tenuifolia, Tulipa urumoffii, Verbascum anisophyllum, V. eriophorum, V. urumovii.

Threats. Major threats are intensive grazing that increases the erosion processes and causes changing in the species composition; terracing of terrains and  forest planting; exploitation (incl. unregulated one) of limestone.

Conservation measures taken. The habitat is included in Annex №1 of the national Biodiversity Act. A very small part of the localities are within the borders of protected areas, mainly within the Ostritza Managed Nature Reserve. The bigger part of the steppe coenoses is within protected zones of NATURA 2000 (Dragoman, Lyubash, Karvav Kamak,  Konyavska Mt, Ostritza, Zemen zones).

Conservation measures needed. Control of the mining of limestone. Proclamation of some of the most representative areas of this habitat as protected areas (in Konyavska, Zemenska, and Dragomanski Chepan Mts., etc.

References. Jordanoff 1936; Pavlov & Dimitrov 2004; Stoyanov & Achtarov 1951b; Stoyanov 1925; Velchev 1962.

Authors: Rossen Tzonev, Marius Dimitrov, Chavdar Gussev


Mountain petrophytic steppes (distribution map)