09H3
Silicate rocks with pioneer herbaceous vegetation
Relationships with habitat classifications. EUNIS: H3.6 Weathered rock and outcrop habitats; PAL. CLASS.: 36.2 Alpine weathered rock and outcrop communities; HD 92/43: 8230 Siliceous rock with pioneer vegetation of the Sedo-Scleranthion or of the Sedo albi-Veronicion dillenii.
Conservation status. BDA, HD.
Category. Vulnerable [VU – A1,2 B2 D2 H2 I J].
General characteristics. The dry, acidic, mainly siliceous rocks and rock walls are widely distributed in the foothills and mountain areas of Bulgaria. The ecological conditions for the development of this habitat type are relatively unfavourable although the areas are mainly flat. They are subjected to various atmospheric factors, water shortage, and as result of the poorly developed or absent vegetation cover, the sun radiation is strong. They are suitable mainly for the representatives of family Crassulaceae and to a more limited extent of some terrophytes. The total projective cover of the phytocoenoses is usually below 30%. The pioneer communities are dominated mainly by succulents like Jovibarba heuffelii, Sedum acre, S. album, S. alpestre, S. annuum, S. hispanicum, S. maximum, S. ochroleucum, Sempervivum erythraeum, S. leucanthum, S. marmoreum etc. Allium cirrhosum, Cerastium arvense subsp. arvense, C. banaticum, C. decalvans, C. moesiacum, Erysimum cuspidatum, Potentilla argentea, Scleranthus neglectus, S. perennis, Silene pusilla, Silene sendtneri, S. waldsteinii, Thymus albanus, T. longicaulis, T. moesiacus, Veronica frutican etc. also participate. Some of these taxa are diagnostic species for the alliance Sedo-Scleranthion biennis. In the composition of the phytocoenoses under consideration are many terrophytes from the alliance Sedo albi-Veronicion dillenii: Alyssum alyssoides, A. desertorum, A. parviflorum, Arenaria serpyllifolia, Crupina vulgaris, Echium vulgare, Erophila verna subsp. praecox, Filago lutescens, Micropyrum tenellum , Minuartia viscosa, Myosotis ramosissima, Scleranthus annuus, S. polycarpos, Sideritis montana, Silene compacta, S. conica, Trifolium arvense, Veronica dillenii, V. verna, Viola kitaibeliana, Vulpia myuros.Some perennials like Allium carinatum, A. rhodopaeum, Alyssum stribrnyi, Gagea saxatilis, Hieracium pilosella, Petrorhagia saxifraga, Poa bulbosa, Potentilla regis-borisii, Rumex acetosella, Sagina saginoides, Satureja montana subsp. kitaibelii, S. pilosa, Scabiosa columbaria, Scleranthus verticillatus, Sedum acre, Silene flavescens, Thymus pulegioides, Umbilicus erectus, U. rupestris, Verbascum rupestre also participate in these communities. As the altitude increases the floristic diversity of the phytocoenoses decreases, since most of the terrophytes occur below 1000 m alt. Among lichens, the most frequently encountered species are from the genera Rhizocarpon spp., Umbilicaria spp., Ramalina spp., and among mosses Ceratodon purpureus, Grimmia spp., Polytrichum piliferum, Riccia ciliifera etc. The syntaxonomy of the communities from this habitat type is related with Koelerio-Corynephoretea,order Sedo-Scleranthetalia and alliance Sedo albi-Veronicion dillenii and Sedo-Scleranthion biennis.
Characteristic taxa.
- Vascular plants: Allium carinatum, A. cirrhosum, A. rhodopaeum, Alyssum alyssoides, A desertorum, A. parviflorum, A. stribrnyi, Arenaria serpyllifolia, Crupina vulgaris, Erophila verna subsp. praecox, Echium vulgare, Hieracium pilosella, Jovibarba heuffelii, Logfia arvensis, Medicago minima, Minuartia viscosa, Myosotis ramosissima, Petrorhagia saxifraga, Poa bulbosa, P. molinerii, Potentilla argentea, Rumex acetosella, Sagina saginoides, Scabiosa columbaria, Scleranthus annuus, S. perennis, S. polycarpos, Sedum acre, S. album, S. alpestre, S. annuum, S. maximum, Sempervivum erythraeum, S. marmoreum, S. leucanthum, Sideritis montana, Silene pusilla, S. compacta, S. conica, S. flavescens, S. sendtneri, S. waldsteinii, Thymus pulegioides, Trifolium campestre, Umbilicus erectus, Veronica dillenii, V. verna, V. fruticans, Vicia lathyroides, Viola kitaibeliana, Vulpia myuros.
- Fungi: Micromycetes – Ascochyta vollubilis, Erysiphe betae, Puccinia acetosae (on Rumex acetosella); Peronospora agrestis (on Veronica verna); Urocystis ornithogali, Ustilago ornithogali (on Gagea bohemica).
- Animals: Oedipoda coerulescens.
Distribution in Bulgaria. In the foothills and mountains of Bulgaria.
Conservation importance. The following rare and endangered species occur in this habitat: Allium cupani, A. rhodopaeum, Alyssum stribrnyi, Micropyrum tenellum, Sedum stefco, Sempervivum ciliosum, etc.
Threats. Air pollution, development of tourist and road infrastructures, extraction of inert materials.
Conservation measures taken. The habitat is in Annex № 1 of BDA. Most of the rocky areas are within existing protected areas of national parks and reserves. However, at lower altitudes they are threatened by the constantly increasing anthropogenic activities. Parts of the localities are in sites of the European Ecological Network NATURA 2000.
Conservation measures needed. Detailed phytocoenological study, mapping and monitoring.
References. Gussev 2005.
Authors: Veska Roussakova, Chavdar Gussev
