40G3

G. Forests

Bog conifer forests and shrubs

Relationships with habitat classifications. EUNIS: G3.E1 Pinus mugo bog woods, G3.E32 Moesian Scots pine mire woods; G3.E6 Nemoral bog Picea woods; PAL. CLASS.: 44.A3 Mountain pine bog woods, 44.A222 Moesian Scots pine mire woods, 44.A42 Nemoral bog spruce woods; HD 92/43: 91D0 *Bog woodland.

Conservation status. BDA, BC, HD.

Category. Vulnerable [VU – A1, 2 B1 C2 D2 E2 F2 G1 H2 IJ L1].

General characteristics. The habitat comprises intrazonal group of mires and bogs, dominated in their upper layers of coniferous trees and shrubs. These very specific Bulgarian vegetation communities are represented by separate fragments of limited area, mainly in West Rhodopi, Vitosha and Rila Mts. They are directly subjected to the influence of near-surface groundwater and to a smaller extent, they directly depend on rainfall. The soils are acidic and wet (Histosols), in some cases poor in mineral salts, in other cases they are rich in nutrients. The bog coniferous forests and shrubs occur mainly in West Rhodopi Mts. (Dospatska Mts.). They grow near riverbeds and waterlogged areas on slanting slopes. The spruce (Picea abies) and the Scots pine (Pinus sylvestris) are the dominating tree species. Although the increased acidity and constant over-wetness are not the optimal environment for the tree species and they are not big, they have their impact on the microclimatic conditions and to some extent determine the composition of the ground vegetation layers. The limited light that reaches the surface of the soil causes the disappearance of the heliophytic species of mosses and vascular plants. The mesotrophic and oligotrophic sphagnum mosses Polytrichum commune, P. strictum, Sphagnum angustifolium, S. capillifolium, S. fuscum, and S. magellanicum occur as single species or in complexes that can often reach more than 1 meter in height. The tree layer is composed mainly of the Scots pine (Pinus sylvestris). The projective cover is high, but the trees are 3 m, rarely 7 m high. At the age of 50–60 years they barely reach 4 m. Sphagnum squarrosum dominates almost everywhere, and together with Aulacomnium palustre, Philonotis fontana, Mnium punctatum, Marchantia aquatica,and partly with Hylocomium splendens form groupings of different sizes where the abundance of flowering species is restricted. Bruckenthalia spiculifolia, Eriophorum vaginatum, Potentilla erecta, Vaccinium myrtillus, Vaccinium vitis-idaea, and Viola palustris occur more often. Higher plants play an essential role in the depressions between the oligotrophic Sphagnum heaps. Together with the already mentioned higher plants, species also occur that are typical for the subalpine and alpine riverside areas and are associated with spruce coenoses with dense canopies where soil and air humidity is high. Among the more widely distributed species are Chaerophyllum hirsutum, Cirsium appendiculatum, Cystopteris fragilis, Dactylorhiza maculata, Deschampsia caespitosa, Equisetum hiemale, E. sylvaticum, Eriophorum angustifolium, Filipendula ulmaria, Geum rhodopaeum, G. rivale, Listera cordata, Lysimachia nummularia, Moneses uniflora, Myosotis scorpioides, Myosoton aquaticum, Oxalis acetosella, Parnassia palustris, Phegopteris connectilis, Potentilla palustris, Pyrola minor, Ranunculus montanus, Scirpus sylvaticus, Soldanella chrysostricta, etc. The heliophytic species are rarer in the spruce forests while in the Scots pine forests their number  is higher.

In some places, on the border between forest and bog coenoses in Rhodopi Mts., the trees are stunted and severely degraded. Among them, heaps of Sphagnum species of different height occur: Dicranum bonjeanii, Polytrichum commune, Sphagnum capillifolium, S. centrale, S. girgensohnii, S. magellanicum, S. palustre, S. rossowii. Bruckenthalia spiculifolia, Bistorta vivipara (= Polygonum viviparum), Carex echinata, C. pallescens, C. panicea, Geum rhodopaeum, Listera cordata, Moneses uniflora, Nardus stricta, Parnassia palustris, Pseudorchis frivaldii, Vaccinium myrtillus, Vaccinium vitis-idaea, Viola palustris also occur.

Vitosha’s spruce forests are distinguished by a low canopy that provides more light for the ground cover plants. High soil moisture, supported by the large amount of rainfall and many springs, is a prerequisite for the high abundance of green forest mosses: Hylocomium splendens, Pleurozium schreberi, Polytrichum commune, Rhytidiadelphus triquetrus, etc. Their peat deposits hold additional amounts of water and contribute to the development of peat mosses. Spruce trees, which prefer moderate soil humidity, gradually loose power, their growth rate is limited, and they finally whither and die. These processes stop where the slope is steeper and the natural drainage of the soil is good.

In Rila, and more limited in Pirin Mts., when the relief is flat or slightly slanting and the groundwater is near to the surface or the surface is almost constantly flooded, peat coenoses of the Dwarf pine develop (Pinus mugo). They occur in the bottom of the cirques and river valleys and usually occupy limited areas. In the past they used to cover larger areas, but partly because of the advancement of succession processes, partly because of climate change, but mostly as a result of anthropogenic impact, their distribution in the contemporary vegetation of the country is not very wide. As a rule, these are meso-oligotrophic peat bogs with dense moss cover of Barbilophozia lycopodioides, Plagiothecium denticulatum, Sanionia uncinata, Sphagnum capillifolium, S. centrale, S. compactum, S. inundatum, Warnstorfia exannulata with the participation of Dicranum fuscescens, D. scoparium, Eurhynchium pulchellum, etc. The shrub layer of the Dwarf pine has high projective cover and cannot be trespassed. Near the stem bases and the procumbent branches microelevations appear  that are covered mainly by Sphagnum species. The conditions are suitable for the occurrence of species from the class Vaccinio-Piceetea: Bruckenthalia spiculifolia, Geranium sylvaticum, Homogyne alpina, Juniperus sibirica, Deschampsia flexuosa, Luzula sylvatica, Rubus idaeus, Vaccinium mytrillus, and V. vitis-idaea. In the more open parts and especially in the older coenoses, the following more heliophytic and hygrophytic species can also occur: Caltha palustris, Carex echinata, C. nigra, Eriophorum vaginatum, Juncus alpinus, Plantago gentianoides, Potentilla erecta, Primula deorum, Pseudorchis albida, etc. Syntaxonomically the position of these coenoses is specific. On the one hand they are coenoses of the Sphagnum peat bogs (Scheuchzerio-Caricetea) and on the other the role of the species of Vaccinio-Piceetea is equally important. Being at the edge of their area of distribution and in different conditions from the ones in Central Europe, these coenoses do not have many of their typical features: the composition and structure of peat bogs at higher altitudes. They have a different floristic composition compared to the vicariant syntaxa from Central and North Europe. The Central European and North-Central European species are absent, such as Chamaedaphne calyculata, Ledum palustre, Pinus rotundata, Rubus chamaemorus, etc. Also, some typical species of the bog conifer forests and shrubs of Pinus mugo from the Carpathians in Romania are also absent: Andromeda polifolia, Betula pubescens, Oxycoccus palustris, etc. There, the thickness of the peat layer varies between 1.5 and 5 m, while in Bulgaria it is often thinner. The Carpathian coenoses, similar to the ones under consideration, belong to Oxycocco-Sphagnetea, the southern borders of which are the Carpathians. In Bulgaria they are classified as subassociation Lerchenfeldio-Pinetum mugo eriophoretosum vaginatae, and belong to class Vaccinio-Piceetea.

Characteristic taxa.

Distribution in Bulgaria. Isolated localities in West Rhodopi, Rila, Pirin and Vitosha Mts.: from 1300 up to 2400 m alt.

Conservation importance. The bog conifer forests and shrubs have a very limited distribution. They are the habitat of some protected species such as Geum rhodopaeum, Listera cordata and Viola palustris and the endemics Cirsium appendiculatum and Geum rhodopaeum.

Threats. These coenoses used to be subjected to felling or burning in many parts of the mountains in the past, as a result of which their total area in the contemporary vegetation of Bulgaria is very limited. The succession processes and the natural aridisation of the environment and, in the last decades, also the anthropogenic pressures including ameliorative activities have caused both drought or over-wetness in these coenoses.

Conservation measures taken. The habitat is included in Annex № 1 of the Bulgarian Biodiversity Act and is a habitat of priority conservation. Parts of the phytocoenoses are within protected areas: Rila National Park and Vitosha Nature Park and sites of the European Ecological Network NATURA 2000.

Conservation measures needed. To include the habitat in the National Biodiversity Monitoring System, assessment of its state, the threats outside protected areas and implementation of ecologically related forestry practices.

References. Dierssen 2001; Petrov 1958; Roussakova 2000; Stefanoff & Jordanoff 1931.

Authors: Anna Ganeva, Veska Roussakova


Bog conifer forests and shrubs (distribution map)