F. Shrub communities

Communities of Astracantha thracica

Relationships with habitat classifications. EUNIS: F7. 332 Northern Thracian collinar phrygana [Astragalus thracicus]; PAL. CLASS.: 33.B2 Northern Thracian collinar phrygana [Astragalus thracicus]; Bondev (1991): 125 Shrub communities of Astragaleta thracici.

Conservation status. BC.

Category. Endangered [EN – A1 B2 C2 D3 F1 G2 H2 I L1].

General characteristics. This habitat encompasses the xerothermic herbaceous and shrub-herbaceous coenoses with the prevalence of the Balkan endemic and Tertiary relic Astracantha thracica (= Astragalus thracicus). They are similar in appearance to the small phrygana shrubs that occur in the Mediterranean part of the Balkan Peninsula and more specifically in East Thrace. They occupy dry places with open communities of rare, mainly aromatic and spiny small shrubs and diverse herbaceous species. The development of many ephemeres and ephemeroids in spring is typical. In summer and autumn only the xeromorphic shrubs remain and they give the special outlook of the landscape. Syntaxonomically these communities belong to order Poterietalia spinosi of class CistoMicromerietea julianae. The communities with A. thracica occur in dry, stony calcareous and silicate places, where the erosion is strong and in many places the bed rock appears on the surface. The slope varies between 5–20 °. These coenoses cover slopes and flat ridges of small hills and heights in East Bulgaria in the belt of the xerophytic oak forests with transitional-Mediterranean climate. More often these habitats are of secondary origin as a result of the degradation of the autochthonous forest vegetation caused by intensive grazing. The soils are dry and shallow and mostly Chromic Cambisols. The projective cover is low and varies between (30)40 and 60%. Astragalus thracica makes small patches or groups. It is a tuft plant up to 40 cm high with spiny, densely branched paripinnate leaves, acuminate stipules and densely pubescent inflorescences.

Together with A. thracica grasses such as Bothriochloa ischaemum, Festuca valesiaca, Sesleria latifolia aredominants and co-dominants in the plant communities with A. thracica in the calcareous areas in East Balkan Range. The participation of Achillea clypeolata, Ajuga chamaepytis, Asperula cynanchica, Astragalus hamosus, Carlina vulgaris, Centaurea diffusa, Cleistogenes bulgarica, Convolvulus cantabrica, Crepis setosa, Dianthus pallens, Echinops microcephalus, Euphorbia barrelieri, E. myrsinites, E. niciciana, Hypericum rumeliacum, Leontodon asper, Melica ciliata, Minuartia glomerata, Onobrychis degenii, Potentilla neglecta, Rhodax canus, Scabiosa rotata, Scorzonera hispanica, Scrophularia canina, Sideritis montana, Teucrium polium is also typical.

On silicate, in the western part of Yambolski Bakadzhik hills, on slopes of 5–10 °, on dry, shallow Phaeozems the following species occur: Allium saxatile, Althaea hirsuta, Asparagus officinalis, Asphodeline liburnica, Aster linosyris, Astragalus onobrychis, Bupleurum apiculatum, Carduus candicans, Carthamus lanatus, Centaurea solstitialis, Cleistogenes bulgarica, Comandra elegans, Crucianella angustifolia, Crupina vulgaris, Desmazeria rigida, Dianthus gracilis, Ferulago sylvatica subsp. confusa, Festuca valesiaca, Genista rumelica, Goniolimon collinum, Heptaptera triquetra, Hypericum montbretii, H. rumeliacum, Iris suaveolens, Medicago falcata, Melica ciliata, Onobrychis caput-galli, Opopanax hispidus, Phlomis herba-venti subsp. pungens, P. tuberosa, Poa bulbosa, Potentilla recta, Psilurus incurvus, Scabiosa micrantha, Stachys angustifolia, Stipa capillata, S. pennata, Thymus callieri, Trifolium purpureum etc. When erosion is very strong A. thracica can become a pioneer species and makes its own coenoses in which almost no other species participate. Single trees or small groups (not more than 15% cover) of Quercus pubescens, Fraxinus ornus, Jasminum fruticans and Paliurus spina-cristi also participate in these coenoses. The cover of the latter species can reach up to 30%.

Characteristic taxa.

Distribution in Bulgaria. East Balkan Range – Sinite Kamani Nature Park, near Sotirya village, East Rhodopi Mts., Thracian Lowland, Toundzha Hilly Country; at 300–800 m alt.

Conservation importance. Apart from Astracantha thracica, that is an endemic and relic species in the Bulgarian flora and is protected by BDA, other species of conservation floristic and geographic importance also occur: Tulipa australis, Cleistogenes bulgarica, Galanthus nivalis, Genista rumelica, Goniolimon collinum, Onobrychis degenii etc.

Threats. Burning and afforestation; damages and destruction of the tufts of A. thracica as a result of grazing; low rate of seed reproduction.

Conservation measures taken. Parts of the communities are within protected areas – Sinite Kamani Nature Park and sites form the European Ecological Network Natura 2000.

Conservation measures needed. Monitoring of the habitat and elaboration of an action plan for the protection of the habitat.

References. Vassilev 1983; Stanev 1984; Stoeva et al. 2004.

Authors: Chavdar Gussev, Dimitar Dimitrov

Communities of Astracantha thracica (distribution map)