20E4

E. Herbaceous communities and communities of lichens and mosses

Alpine acidophilic herbaceous communities near melting snow patches

Relationships with habitat classifications. EUNIS: E4.11 Boreo-alpine acidocline snow-patch grassland and herb habitats; PAL. CLASS.: 36.111 Alpine acid snow-patch communities (36.1111–36.1114); HD 92/43: 6150 Siliceous alpine and boreal grasslands; Bondev (1991): 1 Acidophylous psychrophytous grass (Cariceta curvulae, Festuceta riloensis, Seslerieta comosae, Junceta trifidi, Festuceta airoides, Agrostideta rupestris etc.) and shrub (Saliceta herbaceae, Saliceta retusae, Empetreta nigrae, Vaccinieta uliginosi etc.) communities.

Conservation status. BDA, HD.

Category. Endangered [EN - A1, 2 B1 C2 D3 E2 H3 I J].

General characteristics. The herbaceous phytocoenoses in places with snow drifts on silicate rocks – snow-drift phytocoenoses – are widely distributed in Rila Mts., are more limited in Pirin Mts., and very rare in other relatively high mountains of Bulgaria. The phytocoenoses in Bulgaria are the best developed and most representative phyotocoenoses of that type in the Balkan-Carpathian region. These are pioneer habitats in areas of very low annual temperature and small temperature variations. They occur in the depressions on the ridges and slopes of the mountains, in the glacial cirques, on the screes with small stones below rock outcrops. The exposure is most often northern, rarely eastern or western. In some places, mostly above 2500 m alt., these coenoses can occur on slopes with southern exposure. Such habitats rarely occur at about 2300 m alt., mostly the altitude is above 2400 m alt. The slope is different – in the micro-depressions on the high ridges and slopes there are flat or slightly slanting places. In some places the slope can be 30° or 40°, rarely higher. As a rule the soils are poorly developed – Lithosols (1–4 cm), strongly skeletal, often with small stones on the surface. Some of them are rich in fine, organic substances. The soils are permanently humid and very acidic. The vegetation period rarely is longer than 2–3 months, in some places it is even shorter. The areas that are covered by the phytocoenoses or the complexes of chionophilic coenoses are small and vary from several square meters to several decares.

The high specificity of the habitat is the reason for the relatively good relationships with similar phytocoenoses from the Alps to Pirin and Perister Mts. Many species are common for this vegetation type, independently from the mountain in which it occurs (Arenaria biflora, Cerastium cerastoides, Gnaphalium supinum (= Omalotheca supina), Luzula alpinopilosa, Polytrichastrum sexangulare etc; for the Balkan-Carpathian region common species are Ranunculus crenatus and Plantago gentianoides). However, there are significant differences as well due to the regional and local floras and the specificities of the habitats. It reflects in the classification of the different associations while the syntaxa of higher levels are identical. The following associations have been described from Bulgaria until now: Omalotheco-Alopecuretum gerardii, Alopecuro-Ranunculetum crenati, Omalotheco-Polytrichetum piliferi, Soldanello pusillae-Plantaginetum gentianoidis, Alopecuretum riloensis, Alopecuro riloensis-Plantaginetum gentianoidis, Achilleo (clusianae)-Luzuletum velenovskyi, Leontodonto-Plantaginetum atratae and some plant groups without rank of Polytrichum juniperinum, Polytrichastrum sexangulare, Gnaphalium supinum, Luzula alpinopilosa. As a result of the richness of the Bulgarian flora and the diversity of the local habitats in Rila and Pirin mountains, this considerable number of associations is divided into subassociations. Several chionophil ic phytocoenoses in Rila Mts. are endemic. Most of the mentioned syntaxa are part of a common succession chain and when the area of the snow drifts is larger they make a complicated mosaic with clear borders between the different phytocoenoses and their fragments. In general, the floristic composition of the different phytocoenoses is rich, bearing in mind the unfavourable conditions in which they develop. It is a complicated combination of Arctic, Arctic-Boreal, and Alpine species distributed in SE Europe and SW Asia together with Bulgarian and Balkan endemics. Main edificators are Ranunculus crenatus, Gnaphalium supinum, Arenaria biflora, Taraxacum apenninum, T. bithynicum, Plantago gentianoides, P. atrata, Leontodon rilaensis, Alopecurus riloensis (Bulgarian endemics restricted to Rila Mts.), Alopecurus gerardii, Polytrichastrum sexangulare, Polytrichum piliferum, Luzula alpinopilosa subsp. Velenovskyi, Crocus veluchensis (Balkan endemics), Carex pyrenaica.The abundance of Campanula alpina subsp. orbelica (Balkan endemic), Achillea clusiana, Carex bulgarica, Geum montanum, Sedum alpestre, Poa media and Potentilla ternata (Dacian-Balkan endemics), Cetraria islandica, Ligusticum mutellina, Soldanella pusilla, Dianthus microlepis can also be high. The projective cover in the different phytocoenoses varies from very low up to 60–80%. The plants are very small, often reaching only several centimetres above the ground, especially those whose above-ground parts remain under the snow.

It is a known fact that there is no strict border between Salicetalia herbaceae and Androsacetalia alpinae. In Rila Mtss the phytocoenoses of Oxyria digyna and Poa cenisia subsp. contracta (Oxyrio-Poetum contractae) are close both in distribution and floristic composition with the coenoses of the snow drifts. Some characteristics, including such of their habitats, of the phytocoenoses of Luzula alpinopilosa, that are often affiliated to Salicetalia herbaceae, affiliate them to the group of the phytocoenoses from Androsacetalia alpinae.

Parallel with the development of the soil profile the chionophilic coenoses can evolve into phytocoenoses belonging to Seslerion comosae, where Carex curvula is mostly the edificator. The coenoses from the association Campanulo-Caricetum curvulae often have transitional features between the chionophilic and alpine associations. Rarely, at lower altitudes, these communities can develop into communities dominated by Nardus stricta.

Characteristic taxa.

Distribution in Bulgaria. Mainly in Rila and Pirin Mts, and very limited in the Balkan Range, (2200) 2350–2700 (2800) m alt.

Conservation importance. Pioneer habitats important for the formation of the vegetation in the alpine belt, with rare and endemic phytocoenoses and species: Taraxacum bithynicum, Alopecurus riloensis.These are among the most representative chionophilic coenoses for the Dacian-Balkan region.

Threats. Grazing and intensive tourism have negative impact on the habitat, Conservation measures taken. The habitat is included in Annex № 1 of the Biodiversity Act. It is within the borders of Rila and Pirin National Parks. Some of the localities are within sites from the European Ecological Network NATURA 2000.

Conservation measures needed. No anthropogenic activities should be allowed in and close to these habitats.

References. Bondev 1959, Ganchev 1963, Roussakova 2000.

Author: Veska Roussakova


Alpine acidophilic herbaceous communities near melting snow patches (distribution map)