01D2

D. Mires, bogs and fens

Peat bogs dominated by sedges and grasses

Relationships with habitat classifications. EUNIS: D2.2263 Rhodopide Black-star sedge acidic fens, D2.2265 Balkan Black-star sedge fens; Pal. Class.: 54.4263 Rhodopide Black-star sedge acidic fens, 54.4265 Balkan Black-star sedge fens; HD 92/43: 7140 Transition mires and quaking bogs; Bondev (1991): 5 Hygropsychrophilous (peat bog) communities (Cariceta acutae, Cariceta echinatae, Cariceta rostae, Sphagneta spp., Cariceta lapponi, Primuleta deori, Hygronardeta etc.).

Conservation status. BC.

Category. Endangered [EN – A1 C2 D2 E2 H2 L2].

General characteristics. This habitat type encompasses fens with acidic waters and predominance of true sedges – Carex canescens, C. echinata, C. nigra, C. rostrata, often accompanied by Eriophorum angustifolium, Baeothryon caespitosum (= Trichophorum caespitosum), species of Juncus – J. acutifolius, J. effusus, J. filiformis, or Nardus stricta and Agrostis canina. The mosses are represented by Aulacomnium palustre, Calliergonella cuspidata, Philonotis fontana, Sphagnum girgensohnii, S. platyphyllum, S. russowii, S. squarrosum, S. subsecundum, Straminergon stramineum, Warnstorfia exannulata, W. sarmentosa. Characteristic features of these fens are the low concentration of metal ions (calcium, magnesium, potassium, sodium, etc., known as alkaline metals) and water level reaching or flooding the ground level. The humidity of these fens is maintained by underground waters. The specificity of the phytocoenoses is due to the low sedges and grasses as well as to brown mosses and Sphagnum species. The plant communities can be affiliated to the acidic fens of the order Caricetalia fuscae and the allience Caricion fuscae. Being an extrazonal vegetation type, the phytocoenoses of the acidic fens include many arctic-boreal species. However, as a result of the development of the hygrophytic vegetation in Bulgaria a considerable part of Balkan (including local endemics from certain mountains) and Bulgarian endemics also participate in these plant communities, thus adding some unique characters. The habitat type and related phytocoenoses in Bulgaria occur mostly in the mountains at and above 1300 m alt. The diversity of the climatic conditions at an altitude above 1000 m impacts the characteristics of the habitat, hence the floristic composition of the vegetation that has developed at different elevations. Two main groups of phytocoenoses can be identified from this point of view: mid-mountain, called “mountainous” by some authors, and high-mountain occurring above the timberline, also called “alpine”. The first phytocoenoses occur mostly in West Rhodopi Mts., while the second group can be found mostly in Rila and partly in Pirin Mts. Similar to this type of habitat are the phytocoenoses of the spruce vegetation belt in Vitosha Mts. In the remaining Bulgarian mountains the distribution of the fens is limited. Apart from the climatic conditions, the relief features and the development of the mountains play a considerable role in the composition and structure of the hygrophytic phytocoenoses. Therefore the floristic composition of this vegetation type is mountain-specific. Very often this vegetation has mosaic distributions mixed with other over-wet phytocoenoses such as peat-bogs, spring-water vegetation, typical wet meadows, wet forests or wet scrub. These are fens with Carex nigra and C. echinata,distributed in the mountain and subalpine zones in Bulgaria. The phytocoenoses develop on permanently swampy soils, with surface water, and occur at about 1400–1500 m alt. They are relatively widely distributed in West Rhodopi Mts. They occupy the lowest parts of the river valleys almost everywhere. The species composition is diverse and taxonomically variable. In the central, lower parts of the habitat, where the humidity is more variable, the vegetation cover is more sparse. The main species are: Agrostis canina, Aulacomnium palustre, Bistorta major (= Polygonum bistorta), B. vivipara (= Polygonum viviparum), Carex acuta, C. caespitosa, C. cinerea (= C. curta), C. echinata, C. flava, C. montana, C. ovalis (= Carex leporina), C. pallescens, C. panicea, C. serotina (= Carex viridula), Deschampsia caespitosa, Epilobium palustre, Equisetum hyemale, E. sylvaticum, Eriophorum angustifolium, E. gracile, E. latifolium, E. vaginatum, Festuca rubra, Galium palustre, Geum rhodopaeum, Juncus acutiflorus, J. alpinus, J. articulatus, J. effusus, J. filiformis, J. thomasii, Molinia caerulea, Myosotis scorpioides, Nardus stricta, Parnassia palustris, Sphagnum subsecundum, Warnstorfia exannulata, etc. Aulacomnium palustre, Chiloscyphus polyanthos, Marchantia aquatica, P. fontana, Philonotis serriata, Rhizomnium punctatum, etc. form small groups along running water. A well developed herbaceous layer of Carex echinata, Eriophorum latifolium, Galium palustre, Geum rhodopaeum, Luzula campestris, L. sudetica, Nardus stricta, Potentilla erecta, Trifolium hybridum subsp. elegans, T. spadiceum, etc. develops on the continuous Sphagnum-moss cover. Apart from the phytocoenoses of Bruckenthalia spiculifolia and Sphagnum capillifolium, several small localities dominated by Carex nigra and Carex echinata have been found near springs and streams distributed in Vitosha and Rila Mts., and in the Balkan Range. However, in some places ruderals (Rumex alpinus, Verbascum longifolium subsp. pannosum, etc.), sometimes with high abundance, occur in these localities. The hygrophytic vegetation in the Balkan Range is rare and covers restricted areas.

In Rila and Pirin Mts. the fens have originated on the places of former lakes. Such processes continue nowadays as well – cryoclastic  material accumulates in the glacial lakes and the hygrophytic vegetation gradually develops. More rarely such vegetation develops in the flooded areas along rivers and streams, or in places where the underground water reaches the surface at the foothills of slopes down which they flow. The phytocoenoses under consideration frequently occur in the higher parts of the subalpine vegetation belt in Rila Mts. and more rarely in Pirin Mts. They occur mostly between 2200 and 2400 m alt. and very seldom above 2500 m alt. Typical species for this group of phytocoenoses are Agrostis canina, Aulacomnium palustre, Carex canescens, C. echinata, C. nigra, Epilobium palustre, Eriophorum angustifolium, Juncus filiformis, Luzula sudetica, Parnassia palustris, Phleum alpinum, Scorpidium revolvens, Sphagnum auriculatum, S. palustre, S. subsecundum, Straminergon stramineum, Warnstorfia exannulata, W. sarmentosa.Additionally Deschampsia caespitosa, Eriophorum vaginatum, Potentilla erecta, Plantago gentianoides, as well as some species with wider ecological amplitude like Anthoxanthum ododratum, Cerastium cerastoides, Ligusticum mutellina, Nardus stricta also occur.In some phytocoenoses heath xerothermic species such as Vaccinium uliginosum and Bruckenthalia spiculifolia occur more frequently. This marks the transition to a mesophytic vegetation type dominated by Nardus stricta. Particular for the hygrophytic phytocoenoses in Rila Mts.  is the wide distribution and dominance of the Bulgarian endemic and glacial relic Primula deorum. Its strong root system very often determines to a high extent the conditions in which the remaining species develop. Best adapted to such environment are Aulacomnium palustre, Carex echinata, C. nigra, Nardus stricta, Philonotis fontana, Sanionia uncinata, Sphagnum capillifolium, S. compactum, Baeothryon caespitosum (= Trichophorum caespitosum), Warnstorfia exannulata, etc. The numerous phytocoenoses are classified in several associations that correspond mainly to the stages in the development of the fens. The advancement of the mesophytization leads to the increase of the abundance of Vaccinium uliginosum, V. myrtillus, V. vitis-idaea, Bruckenthalia spiculifolia, Juniperus sibirica, Homogyne alpina, Eriophorum vaginatum, Sphagnum capillifolium, S. warnstorfii. Gradually the fens in Rila and Rhodopi Mts., as well as the ones in the remaining mountains (Vitosha Mts., the Balkan Range, etc.) are replaced by mesophytic vegetation. A general characteristic for the fens in Bulgaria is the wide distribution of species representative of typical peat bogs: Baeothryon caespitosum, Vaccinium uliginosum, Eriophorum vaginatum, etc. Some Balkan and Bulgarian endemics are abundant in the fens: Barbarea balcana, Carex bulgarica, Cirsium heterotrichum, Crocus veluchensis, Gentianella bulgarica, Geum rhodopaeum, Leontodon rilaensis, Pinguicula balcanica, Plantago gentianoides, Primula deorum, P. farinosa subsp. exigua, Sesleria comosa, Veronica rhodopaea, Viola rhodopeia, etc. together with some relics such as Drosera rotundifolia, Juncus triglumis, and Swertia perennis. These species add certain specificities to the phytocoenoses under consideration.

Characteristic taxa.

Distribution in Bulgaria. Mountain areas between 1300 and 2400 m alt.

Conservation importance. Primula deorum, a species protected by the national Biodiversity Act occurs in this habitat as well as the Balkan endemic and relic species: Barbarea balcana, Carex bulgarica, Cirsium heterotrichum, Gentianella bulgarica, Geum rhodopaeum, Juncus triglumis, Leontodon rilaensis, Pinguicula balcanica, Primula farinosa subsp. exigua, Sesleria comosa, Swertia perennis, Veronica rhodopaea, Viola rhodopeia. Fungi of conservation importance have also been registered: Arrhenia lobata, A. spathulata, Galerina paludosa, G. sphagnorum, Psilocybe uda, Trichoglossum hirsutum. The preservation of the natural state of the habitat of these species is necessary for the conservation of their populations. Fens are also important for the water regulation of the region.

Threats. Global warming and aridisation, water and air pollution with heavy metals, increase of the nitrates and nitrites quantities in the water, household wastes, draining, digging of canals, ploughing; invasion of trees and shrubs and mesophytisation cause changes in the species composition of the plant communities.

Conservation measures taken. A considerable part of the territories covered by this habitat are within the borders of Rila, Pirin and Central Balkan National Parks, Vitosha Nature Park and sites of the European Ecological Network NATURA 2000 in Bulgaria.

Conservation measures needed. To include the habitat in the National System for Biodiversity Monitoring. The assessment of the value of the habitat and the threats outside protected areas will make possible the identification of suitable concrete measures for its restoration and protection.

References. Bondev 1991; Roussakova 2000; Stefanoff & Jordanoff 1931.

Authors: Anna Ganeva, Veska Roussakova


Peat bogs dominated by sedges and grasses (distribution map)