26E4

E. Herbaceous communities and communities of lichens and mosses

Sub-alpine acidophilic mesophytic grasslands mainly with mat-grass swardsof Nardus stricta

Relationships with habitat classifications. EUNIS: E4.318 Oro-Moesian mat-grass swards; PAL. CLASS.: 36.318 Oro-Moesian mat-grass swards; HD 92/43: 6230 *Species-rich Nardus grasslands on siliceous substrates in mountain areas; Bondev (1991): 3 Scrub community (Pineta mugi) partly mixed with potential shrubs (Alneta viridis, Saliceta waldsteinianae etc.), secondary shrubs (Junipereta sibiricae etc.), dwarf shrubs (Vaccinieta vitis-idaeae etc.) and grasses (Nardeta strictae, Festuceta validae etc.), 8 Acidophilous psichrophytous grass communities (Nardeta strictae, Festuceta validae, Bellardiochloeta violaceae, Agrostideta capillaris etc).

Conservation status. BDA, HD.

Category. Vulnerable [VU – A1, 2 B2 C1 G2 I].

General characteristics. This habitat type occurs in the Bulgarian mountains (1600–2500 m alt.) and has a wide distribution, and diverse floristic composition. Its syntaxonomy has not been studied completely. The high vertical range, approx. 1000 m, is the reason for a vertical differentiation of the existing numerous mesophytic herbaceous phytocoenoses. Some of them are related with the upper part of the subalpine sub-belt, above 2000–2100 m alt., where only the coenoses of the dwarf pine are of primary origin; others occur mainly between 1600 and 2100 m alt. in the coniferous belt of the high mountains.

The phytocoenoses of Nardus stricta are the most widely distributed phytocoenoses in the subalpine belt in the Bulgarian mountains, especially in its higher parts. This species is very adaptable to changing environmental conditions and at the same time is a strong edificator that is also very well adapted to trampling and grazing. Therefore it is a main edificator in secondary coenoses in the subalpine belt in the Bulgarian mountains and covers large areas. The slope, exposure, soil features and humidity vary very widely (the phytocoenoses from over-wet areas and peat bogs belong to another habitat type). However, the northern exposure and slopes above 30° are rare. In the prevailing part of the coenoses of Nardus stricta the species is a monodominant and sometimes even the only species present (mostly as a result of extensive grazing). Other co-dominants with Nardus stricta are Agrostis rupestris, Carex caryophyllea, Festuca airoides, F. nigrescens, Poa media. In medium-high mountains co-dominants are Agrostis capillaris, Deschampsia flexuosa, Thymus spp. etc. Despite this diversity the significant part of these coenoses belong to the association Diantho (microlepis)-Nardetum strictae, part of the Carpathian-Balkan alliance Potentillo-Nardion.

Festuca nigrescens dominates in places with moderately humid and well aerated soils. These phytocoenoses are part of the diversity of the subalpine vegetation but are not widely distributed, although Festuca nigrescens is a frequent subdominant or assectator. The phytocoenoses of Avenula versicolor, Carex caryophyllea, Poa media etc. have similar characteristics.

The phytocoenoses of Carex bulgarica belong to the same group and are very well represented in the upper part of the subalpine belt in Rila Mts. They develop on flat or slightly sloping areas with humid, medium strong, strongly skeletal soils. They are on the margin between the group of the habitat type under consideration and the habitat type of peat bogs/swamp vegetation (Scheuchzerio-Caricetea fuscae). Homogyne alpine, Leontodon rilaensis, Ligusticum mutellina, Pinguicula balcanica, Plantago gentianoides also participate in these phytocoenoses, together with Nardus stricta, Luzula sudetica in some places and in others – with Campanula alpina, Poa media, Sesleria comosa. They also occur in the alpine belt in  relief depressions beside snow drifts.

The phytocoenoses that have been considered so far belong to associations of the alliance Poetentillo (ternatae) – Nardion of the order Seslerietalia comosae.

Only two mountains in Bulgaria are higher than 2400–2500 m, the altitude where the border between the alpine and subalpine belts is determined by climatic conditions. But there are also some coenoses whose composition and structure make them characteristic for the alpine belt and develop below this border, at 2300 m alt. However, they do not change the general characteristics of the subalpine vegetation cover. In the remaining Bulgarian mountains that reach 2000–2300 m alt. on the ridges and the neighbouring slopes, coenoses with floristic composition and structure that is very close to the ones in Rila and Pirin Mts. occur together with the typical subalpine phytocoenoses. In the same time they comprise elements typical for the subalpine belt. These coenoses are of primary but also of secondary origin. Such phytocoenoses are dominated by Festuca airoides, Juncus trifidus, Sesleria comosa and even (although rarely) by Festuca riloensis and Carex curvula. In these coenoses, together with other typical alpine species, species like Agrostis rupestris, Dianthus microlepis, Jasione laevis subsp. orbiculata, Luzula italica, Potentilla ternata, Primula minima also occur. Species distributed in the subalpine belt and some times even in lower belts, also participate, mostly Bellardiochloa variegata (= Bellardiochloa violacea), Campanula abietina, Festuca nigrescens and Deschampsia flexuosa. Some of these phytocoenoses reach down to 1800 m alt. On the other hand, subalpine coenoses can occur in the beech vegetation belt at the border of the subalpine belt that occurs at approx. 1600 m alt. in Bulgaria. Mainly in the lower subalpine sub-belt, between 1500 and 1700–1800 m alt., and more rarely up to 1900 m alt. the coenoses of Agrostis capillaris is mixed mainly with Nardus stricta. They are among the main herbaceous mesophytic coenoses in the Bulgarian mountains in this altitudinal range. Additionally, their distribution is more typical for the medium-high Bulgarian mountains. They do not play the same role in Rila and Pirin Mts. compared to, for instance, the ridge of the Balkan Range and Rhodopi Mts. These coenoses usually cover northeastern, eastern and southern slopes with moderate slope, up to 20–25°, or flat areas. The soils are moderately humid to humid. They are often eroded because in many places they have originated on the places of burnt juniper or coenoses of Vaccinium myrtilus. Sometimes the burning has happened several times in one place and has caused erosion, and the A soil horizon is almost completely destroyed. Most of the coenoses of Agrostis capillaris have high vegetation cover of 95–100%. The average height of the herbaceous layer is 40–60 cm, in some places even higher. Together with Nardus stricta, Agrostis capillaris also makes mixed coenoses in which Carex kitaibeliana, Festuca dalmatica, F. nigrescens, Deschampsia flexuosa, also participate, separately or in different combinations. In the Balkan Range Thymus spp. also occurs. Actually, the differences between the coenoses of Agrostis capillaris are more in the abundance of the species than the species composition itself. Moreover, the floristic composition of these coenoses does not differ considerably from the one of the coenoses of Nardus stricta and Festuca nigrescens. Together with the already mentioned species, Alchemilla glaucescens, Antennaria dioica, Bellardiochloa variegata, Bruckenthalia spiculifolia, Campanula patula subsp. epigaea, Crocus veluchensis, Cynosurus cristatus, Euphrasia liburnica, Genista depressa, Hieracium hoppeanum, Hypericum perforatum, Leontodon autumnalis, Luzula italica, L. multiflora, Ligusticum mutellina, Poa media, Potentilla ternata, Trifolium repens, Vaccinium myrtillus, V. vitis-idaea, Veronica chamaedrys, V. officinalis etc. also often occur.

The presence, and in some places the high abundance of Verbascum longifolium subsp. pannosum, is a proof of intensive grazing. The mosses do not play significant role in the coenoses under consideration. Polytrichum juniperinum, Hypnum cupressiforme occur more frequently. Lichens, mainly Cetraria islandica occur  in some places. . Some of the phytocoenoses of Festuca balcanica subsp. balcanica that occur in the silicate areas of the subalpine belt of West and Central Balkan Range are closer to the mesophilic rather than to the xerophilic vegetation. They develop more often on northern slopes. The soil is relatively fresh and deep, although there are places with shallow, strongly eroded and skeletal soil. The Balkan fescue is a strong edificator and makes rather strong tufts, hence the monodominant coenoses are very well distributed. Chamaecytisus austriacus, Deschampsia flexuosa, Festuca nigrescens, Genista depressa, Juniperus sibirirca, Luzula luzuloides, L. sylvatica, Vaccinium myrtillus also occur in these coenoses.

Many of the above mentioned coenoses are of secondary origin in Bulgaria. The present succession processes cause the replacement of the coenoses of Naruds stricta by other herbaceous or shrub communities that most often used to be part of the autochthonous vegetation. The coenoses of Chamaecytisus absinthioides develop very aggressively in the mountains of southern Bulgaria. This process is mostly due to the fact that grazing has almost stopped in the last 1–2 decades rather than to global climate change.

Characteristic taxa.

Distribution in Bulgaria. In all Bulgarian mountains above 1500 m alt.

Conservation importance. Many herbaceous species from the high-mountain flora in Bulgaria occur in these coenoses. Some of these species occur mainly in the habitat under consideration. A considerable number of regional and local endemics as well as protected species occur, among which are Anemone narcissiflora, Meum athamanticum, Phyteuma confusum.

Threats. The overgrazing and trampling, as well as the anthropogenic activities that cause xerophytisation and degradation of the habitat such as construction of roads and tourist paths, intensive tourism. The habitats of phytocoenoses with rich species composition have not degraded. The phytocoenoses with poor composition or with participation of more plastic species have undergone negative changes as a result of bad management. The termination of grazing has caused (natural) restoration of forest and shrub vegetation in the habitats of the coenoses under consideration, thus deteorating them.

Conservation measures taken. The habitat is included in Annex № 1 of BDA and is of conservation priority. Significant parts of the habitat are within the borders of protected areas – Rila, Pirin and Central Balkan National Parks, Vitosha Nature Park, etc. as well as in sites of the European Ecological Network NATURA 2000.

Conservation measures needed. Complete study of the phytocoenoses in the habitat type under consideration in the Bulgarian mountains; identification and protection of the rare and endangered coenoses. Moderate grazing, limitation of the direct negative impact on the habitat and the environment in the mountains.

References. Bondev 1966; Kochev 1967; Roussakova 2000; Stoyanov et al. 1951.

Author: Veska Roussakova


Sub-alpine acidophilic mesophytic grasslands mainly with mat-grass swards of Nardus stricta (distribution map)