03D2
Transitional mires and quaking bogs
Relationships with habitat classifications. EUNIS: D2.3 Transition mires and quaking bogs; Pal. Class.: 54.5 Transition mires; 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. BDA, BC, HD.
Category. Endangered [EN – A1, 2 C2 D2 E2 G2 H3 L2].
General characteristics. The transitional mires and quaking bogs develop in areas with high underground waters and bad drainage as well as on the periphery of the glacial lakes and flooded areas along rivers. They occupy relief depressions or sloping areas that stay permanently wet from the running waters. The absence of constant surface water is typical. The hygrophytic vegetation is dominated by sedges and bog mosses (mainly Sphagnum spp.). Brown mosses are more seldom. The over-wetness, low temperatures, low oxygen and trophic (especially nitrogen and phosphorus) content, high acidity (pH<6,5), and absence of free magnesium and calcium ions presupposes the accumulation of semi-decayed mass (peat) with different thickness. Gradually, the accumulating peat isolates the plants from the mineral basis and the rains, and snowfalls remain the only source of water and nutrients. Morphologically the bog consists of three main layers: mineral substrate, above it a catothelm (a layer of dense peat with permanent or slightly varying water content and absence of atmospheric oxygen and aerobic organisms), and the surface layer (acrothelm, 10–50 cm thick), characterized by intensive variation of the water content, relatively high content of aerobic bacteria and the presence of living plants. The Sphagnum peat-bogs are heterotrophic complexes with mosaic vegetation cover. The elevations of the microrelief create oligotrophic conditions, while the relief depressions – meso- and eutrophic conditions. The plant communities in the transitional mires have rich species composition, in some places including endemic plants: Primula deorum, Pinguicula balcanica, Primula farinosa subsp. exigua, Pseudorchis frivaldii.Acidophyllous and basophyllous phytocoenoses exist, dominated by Carex rostrata, including Carex cinerea (= C. curta), C. limosa, C. nigra, and mostly Sphagnum angustifolium, S. auriculatum, S. flexuosum, S. riparium.In places with hard water Carex rostrata grows together with Sphagnum contortum, S. squarrosum, S. teres, S. warnstorfii or with the brown mosses Calliergon giganteum, Scorpidium scorpioides, Campylium stellatum. Another group of phytocoenoses are these of Carex limosa, in the peat-bogs of the higher parts of Vitosha Mts. and Central Rhodopi Mts. (Smolyan region). Eriophorum gracile and Menyanthes trifoliata can occur accompanied by the mosses Bryum pseudotriquetrum, Calliergon giganteum, Scorpidium revolvens, S. scorpioides, Straminergon stramineum, Warnstorfia exannulata, or Sphagnum papillosum, S. subsecundum. Some parts of the transitional coenoses are dominated by Agrostis canina, Carex nigra, Eriophorum vaginatum, Polytrichum commune,or Molinia caerulea with Sphagnum cuspidatum.
The vegetation of this habitat type belongs to order Caricetalia fuscae (associations Primulo-exiguae-Caricetum echinatae, Cirsio heterotrichi-Caricetum nigrae, Bruckenthalio-Sphagnetum capillifolii).
In West Rhodopi Mts. when the turf layer is thicker, restricted areas with Sphagnum capillifolium, S. fuscum, and S. magellanicum occur. These species are indicative of oligotrophic conditions.These areas are occupied by Bruckenthalia spiculifolia, Carex echinata, Eriophorum vaginatum, Vaccinium myrtillus, V. vitis-idaea, etc. As the soil humidity increases near the mountain slopes the abundance of green mosses Hylocomium splendens, Pleurozium schreberi, Polytrichum commune, Rhytidiadelphus triquertrus increases as well.
This type of bogs occurs in the whole Palaearctic region.
Characteristic taxa.
- Vascular plants: Allium schoenoprasum, Baeothryon caespitosum (= Trichophorum caespitosum), Bistorta major (= Polygonum bistorta), Bruckenthalia spiculifolia, Carex acuta, Carex cinerea (= C. curta), C. echinata, C. limosa, Cirsium appendiculatum, C. heterotrichum, Deschampsia caespitosa, Drosera rotundifolia, Epilobium palustre, Eriophorum gracile, E. latifolium, E. vaginatum, Geum coccineum, Hammarbya paludosa, Lycopodiella inundata, Menyanthes trifoliata, Pedicularis palustris, Potentilla erecta, P. palustris, Pseudorchis frivaldii, Succisa pratensis, Viola palustris; mosses – Calliergon giganteum, Calliergonella cuspidata, Hamatocaulis vernicosus, Meesia longiseta, Scorpidium revolvens, S. scorpioides, Sphagnum angustifolium, S. centrale, S. cuspidatum, S. fallax, S. papillosum, S. riparium, S. subsecundum, S. teres, S. warnstorfii, Warnstorfia sarmentosa.
- Fungi: Macromycetes – Cystoderma amianthinum, Galerina mniophila, G. mycenoides, G. paludosa, G. sphagnorum, Hygrocybe cantharellus, H. miniata, Mitrula paludosa, Mycena megaspora, Pholiota myosotis, Psilocybe polytrichi, P. uda, Scutellinia scutellata, Trichoglossum hirsutum.
- Animals: Invertebrates – Galba truncatula, Aeshna juncea, Ischnura pumilio, Lestes dryas, Sympetrum flaveolum;Vertebrates: Rana temporaria, Neomys anomalus.
Distribution in Bulgaria. This habitat type is distributed in the high mountains of Bulgaria: Rila, Pirin, Vitosha, Osogovska Mts., West and Central Balkan Range, often above the timberline or close to it in open herbaceous places in rare forests. In West Rhodopi Mts. and Sredna Gora Mts. this habitat occurs at lower altitudes.
Conservation importance. This habitat type is important for the ion significance: Carex limosa, Drosera rotundifolia, Lycopodiella inundata, Potentilla palustris, Primula deorum, Viola palustris. Also some fungi of conservation importance occur: Arrhenia lobata, A. spathulata, Galerina paludosa, G. sphagnorum, Mitrula paludosa, Pholiota myosotis, Psilocybe uda, Trichoglossum hirsutum. The following species from the Red List of Bulgarian mosses also occur: Barbilophozia kunzeana, Breidleria pratensis, Calliergon giganteum, Calypogeia neesiana, C. sphagnicola, Cephalozia loitlesbergeri, Dicranum undulatum, Helodium blandowii, Meesia uliginosa, Mylia anomala, Odontoschisma sphagni, Scapania paludicola, Scorpidium revolvens, S. scorpioides, Tomentypnum nitens, Trematodon ambiguus, as well as Sphagnum cuspidatum, S. fallax, S. obtusum, S. riparium, S. subfulvum, S. subnitens. These species are strictly adapted to the specific ecological conditions of the bogs and cannot endure drought and changes in the acidity of the water and in the content of nitrogen, phosphorus, sulphur, and organic substances. The habitat has water regulation and water preservation functions.
Threats. Global warming and aridisation, water and air pollution with heavy metals increase of the content of nitrates and nitrites in the water, household waste, draining, digging of canals, ploughing.
Conservation measures taken. A considerable part of this habitat type is within Rila, Pirin and Central Balkan National Parks, Vitosha and Rilski Manastir Nature Parks and in NATURA 2000 sites in Bulgaria. The habitat is included in Annex № 1 of the Biodiversity Act.
Conservation measures needed. To include the habitat in the National Biodiversity Monitoring System and to assess its state and threats beyond the borders of protected areas thus making possible the identification of suitable measures for its conservation and restoration.
References. Bondev 1991; Hájek et al. 2005b; Natcheva et al. 2006; Nedeva 1975; Petrov 1958; Roussakova & Ganeva 2001; Roussakova 2000.
Authors: Anna Ganeva, Veska Roussakova
