22E4

E. Herbaceous communities and communities of lichens and mosses

Alpine acidophilic grasslands

Relationships with habitat classifications. EUNIS: E4.3941 Oro-Moesian crooked sedge grasslands, E4.39421 Rhodopide Festuca riloensis grasslands, E4.3943 Oro-Moesian Festuca airoides grasslands, E4.3944 Oro-Moesian Sesleria comosa grasslands, E4.3945 Oro-Moesian Agrostis rupestris grasslands, Juncus trifidis grasslands; PAL. CLASS.: 36.3941 Oro-Moesian crooked sedge grasslands, 36.39421 Rhodopide Festuca riloensis grasslands, 36.3943 Oro-Moesian Festuca airoides grasslands; 36.3944 Oro-Moesian Sesleria comosa grasslands; 36.3945 Oro-Moesian Agrostis rupestris grasslands; HD 92/43: 6150 Siliceous alpine and boreal grasslands; Bondev (1991): 1 Acidophilous and 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. Vulnerable [VU – A1, 2 B1 C2 D2 H2].

General characteristics. This habitat type comprises alpine herbaceous phytocoenoses on silicate bedrock that include Arctic-Alpine, Alpine and endemic taxa. It occurs in the uppermost parts of the mountains subjected to strong winds (peaks, ridges, slopes with different exposure and slant, etc.). They develop at and above 2500 m alt. and are best represented in Rila Mts. on the Balkan Peninsula. An Alpine belt on silicate bedrock is distinct only in Rila Mts. . In Pirin Mts., despite its high altitude (almost equal to this of Rila Mts.), the Alpine belt and the Alpine vegetation type is not as well developed as in Rila Mts. This is due to the specificities of the relief –absence of well-developed wide mountain ridges at high altitudes, very rocky and stony relief, etc. Very rarely single phytocoenoses of Alpine type can occur within the borders of the subalpine sub-belt, but they cover small areas and the characteristics of the subalpine vegetation are preserved. Fragments of an alpine vegetation can be found in almost all mountains in Bulgaria the altitude of which is above 2000 m. The main prerequisite for the development of such coenoses is the strong northwestern winds that blow almost throughout the whole year on the open ridges of the Bulgarian mountains. The silicate rocks are granites, sienites, gneiss, etc. The soils are histic Umbrosols, with different degree of development and strength, moderately humid (in some places during the summer months even dry), with different composition of skeletal material in different parts of the mountains. Their structure makes them prone to wind erosion when the vegetation is destroyed. The permanent strong winds blow away the snow cover of the high ridges, peaks and slopes (one of the prerequisites for the development alpine phytocoenoses in the lower mountains also) and place the plants in extreme conditions. The vegetation period is short, approx. 4 months. The plants are small, their development is slow. The projective cover of the vegetation varies and depends upon the type and successional stage of the phytocoenoses.

The floristic composition of the alpine phytocoenoses is relatively poor. In the alpine belt of Rila Mts. approx. 100 plant species occur, excluding bryophytes. Some of them are related only with the alpine vegetation type, others have a wider vertical range of distribution. Despite the considerable altitude, the exposure, slope, soil strength and other specificities of the habitat have an impact on the composition of the phytocoenoses. However, these differences reflect more the abundance of certain species and less the presence or absence of species in the different phytocoenoses. This common feature of the Alpine vegetation type in Europe makes syntaxonomical studies difficult. The main community-forming species are Sesleria comosa and Festuca riloensis (Balkan endemics), Carex curvula and Agrostis rupestris (Alpine floristic elements), Juncus trifidus and Festuca airoides (Boreal floristic elements). Several other edificator species with considerably restricted distributions can also be added: Carex kitaibeliana (the species is distributed in the Pyrenees, Apennines and the Balkans, and has wide ecological amplitude), Carex tricolor (Bulgarian endemic), Carex rupestris, etc. The larger part of the alpine phytocoenoses belongs to two main associations: Carici-Festucetum riloensis and Agrostio-Seslerietum comosae, part of the regionally distributed alliance Seslerion comosae on the Balkans. The habitats of the first association are subjected to strong winds, the soils are less developed (in some places are skeletal and rather dry in summer). This presupposes the wider distribution and dominance of Festuca riloensis. Its phytocoenoses are localized in places unfavourable for vegetation development in the Alpine belt. As a rule these are the places subjected to strong, cold, northwestern winds on the mountain ridges. In winter months the winds blow away the snow and the plants remain unprotected from the cold and drying wind. It is interesting to mention that in the mountains on the Balkans, obviously as a result of another complex of ecological conditions, the phytocoenoses of Festuca riloensis occur in places more favourable for vegetation development. In Bulgaria, the phytocoenoses of this are poorest in species, with lowest productivity and very often with very low projective cover . The coenoses of this association develop on relatively stronger and more humid soils,  mainly in relief depressionson northern mountain slopes where the snow lasts longer. The phytocoenoses of this association are dominated by Carex curvula. The vegetation projective cover is a little higher than the one of Festuca riloensis coenoses. Species that need high soil humidity such as Primula minima, Campanula alpina, Ranunculus crenatus, etc. have higher abundance in these coenoses. Carex curvula does not form dense tufts, hence the development of more species is favoured.

The second association develops on stronger soils, its localities are more protected from winds, the soil retains more  water in summers. Sesleria comosa dominates in such habitats. The phytocoenoses of this species are more widely distributed than the coenoses of the previous two species. Four associations have been identified within the association of Sesleria comosa,reflecting the variation in the characteristics of the habitat. Very often the projective cover is high in this group of phytocoenoses, the phytomass per unit area is definitely higher compared to the association of Festuca riloensis and Carex curvula.

Very often the abundance of Festuca airoides is very high and even equal to the abundance of the other three main community-forming species (Sesleria comosa, Festuca riloensis and Carex curvula). Agrostis rupestris, Antennaria dioica, Armeria alpina, Avenula versicolor, Campanula alpina subsp. orbelica, Dianthus microlepis, Juncus trifidus, Luzula italica, Pedicularis orthantha, P. verticillata, Poa media, Potentilla ternata, Primula minima, Scleranthus neglectus, Thymus jankae, Veronica bellidioides, Cetraria islandica occur very often in the alpine phytocoenoses, but with different abundances.

Coenoses very similar to the ones that occur in Rila Mts. can be found in the Balkan Range, on Botev, Malak Yumruk, and Zli Vrah peaks,. Some of these coenoses are dominated by Festuca riloensis, others by Juncus trifidus (mainly in stony areas), Festuca airoides, Carex curvula, etc. The floristic composition of the alpine phytocoenoses in other parts of the Balkan Range and on the peaks in Slavyanka, Belasitsa and Ossogovo Mts. are similar to that of the coenoses in the alpine belts of Rila and Pirin Mts. However, very often these coenoses include elements from the subalpine herbaceous vegetation type: Bellardiochloa variegata (= Bellardiochloa violacea), Bruckenthalia spiculifolia, Deschampsia flexuosa, Festuca nigrescens, etc. This is particularly true for communities dominated by Sesleria comosa and Festuca airoides. Most often these communities occur within the subalpine vegetation belt, i.e. at lower altitudes.

The phytocoenoses dominated by Agrostis rupestris have a very limited distribution in the alpine belt. They cover small, very eroded areas, with shallow, strongly skeletal soils. They have poor floristic composition, low projective cover and utterly low productivity.

The Bulgarian endemic Carex tricolor can also be a dominant, although very rarely, in Rila Mts. Its phytocoenoses occur within the subalpine belt on relatively well developed soils. The places are moderately slanting. Some of the slopes are subjected to northwestern winds, but below the ridges the snow is not blown away in winters. In summers the soil is humid enough. Other rare alpine communities are these of Carex ericetorum var. approximata. This species occurs only in the alpine belts of Rila and Pirin Mts. but coenoses dominated by it have been found only in Rila Mts. The localities are on the mountain ridges, very stony and relatively dry. The projective cover is 60–80%. Particularly interesting among all rare phytocoenoses that develop on silicate in the alpine belt of the Bulgarian mountains are these of Carex rupestris. They occur mostly in Rila Mts., and are more limited in Pirin Mts., above 2400 m, both on silicate and limestone. All alpine phytocoenoses belong to the autochthonous vegetation of these mountains. Although they do not have very high productivity they have been used for centuries as pastures.

Characteristic taxa.

Distribution in Bulgaria. Mainly in Rila and Pirin Mts.; fragments of this habitat type occur also in the Balkan Range, Vitosha, Rhodopi, Ossogovo, Slavyanka Mts. at (2000) 2500–2925 m alt.

Conservation importance. This habitat type is very typical and representative of the alpine vegetation in the mountains of the Balkans and of Bulgaria. The coenoses of Sesleria comosa and Festuca riloensis are endemic. Balkan endemics such as Pedicularis orthantha and Campanula alpina subsp. orbelica as well as rare plants (Gentiana frigida, Pedicularis oederi, Phyteuma confusum, Pulsatilla vernalis, etc.) (protected by law) and some fungi (Arrhenia spathulata, Rutstroemia calopus) are of conservation importance. Phytocoenoses rare for the country are Festuco riloensis-Caricetum rupestris, Caricetum tricolori, etc.

Threats. Grazing and intensive tourism. The alpine vegetation has been used for grazing for centuries. However, the habitats are sensitive, the vegetation and soils are very vulnerable as a result of trampling and destruction of the grass tufts by people and animals. As a result of the intensification of tourism in the last decades roads, ski tracks and other tourist facilities have been built. Thus the human presence has increased and the alpine vegetation has been destroyed.

Conservation measures taken. The habitat is included in Annex 1 of BDA. Parts of the Alpine acidophilic grasslands are within the borders of Rila, Pirin and Central Balkan National Parks, Vitosha Nature Park and sites of the European Ecological Network NATURA 2000.

Conservation measures needed. Monitoring of the habitat state and strict implementation of the restrictive regimes of the Parks.

References. Bondev 1991; Roussakova 2000; Stoyanov et al. 1951.

Author: Veska Roussakova


Alpine acidophilic grasslands (distribution map)