05F2

F. Shrub communities

Mountain scrub of Siberian juniper (Juniperus sibirica)

Relationships with habitat classifications. EUNIS: F2.231 Mountain scrub Juniperus nana; PAL. CLASS.: 31.431 Mountain scrub Juniperus nana; HD 92/43: 4060 Alpine and Boreal heaths; Bondev (1991): 3 Scrub community (Pineta mugi) partly mixed with potential shrubs (Alneta viridis, Saliceta waldsteinianae etc.) and secondary shrub (Junipereta sibiricae etc.), dwarf shrub (Vaccinieta vitis-idaeae etc.) and grass community (Nardeta strictae, Festuceta validae etc.), 6 Siberian juniper community (Junipereta sibiricae) mostly mixed with secondary shrubs (Chamaecytiseta absinthioides, Vaccinieta myrtilli, Vaccinieta vitis-idaeae, Vaccinieta uliginosi etc.) and grass communities (Nardeta strictae, Festuceta validae etc.), 9 Calciphilous shrub, dwarf shrub and grass communities (Festuceta penzesii, Sesleria korabensis, Astragaleta angustifoliae, Dryeta octopetalae, Chamaecytiseta absinthioides, Junipereta sibiricae, Junipereta pygmaei etc.), 25 Shrubs of Siberian juniper (Junipereta sibiricae), small-sized juniper (Junipereta pygmaei), Chamaecytiseta absinthioides etc. replacing spruce (Picea abies), Balkan pine (Pinus peuce) and Silver pine (Pinus sylvestris), 31 Shrub (Junipereta sibiricae, Chamaecytiseta absinthioides) and grass (Festuceta penzesii, Festuceta pirinensis, Festuceta hirtovaginatae etc.) communities replacing Pinus heldreichii forests.

Conservation status. BDA, HD.

Category. Nearly Threatened [NT – A1, 2 B1 C1 D1 I L3].

General characteristics. Siberian juniper is a procumbent shrub with needle-like leaves distributed in the Arctic region and in the mountains of the temperate region of the northern hemisphere. It grows well both on silicate and limestone. The phytocoenoses of this species in Bulgaria occur above 1500 m alt. The exposure and relief are not significant for the formation of these coenoses: mountain ridges, slopes with different slant, depressions. The soil characteristics are very different – from shallow Lithosols to well developed, slightly or strongly eroded soils, with more or less skeletal material, Umbrosols or Cambisols. Pioneer communities can develop on rocks or large stone pieces, stone rivers (also called stone streams or stone fields). The autochthonous communities of the Siberian juniper are relatively rare and cover mostly small areas. The secondary phytocoenoses that replace the dwarf pine or coniferous forest in the subalpine belt are more widely distributed. The procumbent habitus of this shrub makes possible its survival in some places also on the high alpine ridges, at about 2500 m and above which are subjected to constant, strong winds. In such places the height of the shrubs can be only several centimetres. Sometimes, solitary shrubs or groups of shrubs can occur in peat bogs in the large mountain depressions. The exceptional diversity of habitats in which the Siberian juniper occurs is the reason for the floristic diversity of its phytocoenoses. The structure of these phytocoenoses is also very diverse with regard to the abundance and edificator role of the juniper. In some communities this species covers 100% of the soil surface and few other species manage to grow and overcome it. In other coenoses the distribution of the Siberian juniper is more limited and it appears only as single shrubs or in small groups, and there are favourable conditions for the development of other species among them.

In general the different combinations of habitat characteristics and floristic composition of the phytocoenoses can be classified in two main habitat subtypes: phytocoenoses on silicate rocks with acidic soils and phytocoenoses on limestone, marble and other calcareous rocks.

1. The phytocoenoses of the Siberian juniper on silicate rocks with acidic soils. Since acidic soils are more widely distributed in Bulgaria the phytocoenoses of the Siberian juniper from this group cover larger areas in all high mountains in the country. Despite their rich floristic composition the main species in the coenoses are not many and the phytocoenoses are grouped in three main associations related to three main habitats. The association Campanulo abietinae-Juniperetum sibiricae is most widely distributed. It includes mesophytic phytocoenoses from the subalpine belt. Different berries (mainly the black berry) are sub-dominants and edificators in this association. Deschampsia flexuosa, Rhytidiadelphus triquetrus are well represented as well and in some places Vaccinium uliginosum, Cetraria islandica, Luzula luzuloides, etc. also occur. Bruckenthalia spiculifolia is a characteristic species for this association, but its abundance is very limited. The phytocoenoses in which Bruckenthalia spiculifolia is a sub-dominant occur mostly in the Balkan Range on relatively warmer, drier and shallow eroded soils, and may be belong to the association Junipero-Bruckenthalietum that occur in the mountains of former Yugoslavia.

The second association, Festuco-Juniperetum sibiricae, comprises the phytocoenoses of the Siberian juniper that occur mostly in warmer and drier habitats compared to the previous association. They occur mostly on stony slopes with more or less developed, mainly medium-deep Umbrosols. Festuca valida is the subdominant. Agrostis rupestris, Anthoxanthum odoratum, Calamagrostis arundinacea, Carex kitaibeliana, Deschampsia flexuosa, Festuca airoides, Luzula luzuloides, Poa media, Thymus spp., etc. also often occur. The species composition of this association is very rich.

Association Seslerio-Juniperetum sibiricae is of alpine type in general but exceptionally and at suitable conditions these phytocoenoses can occur also at lower altitudes. The habitats are unfavourable and the floristic composition is relatively poor. Apart from the two edificators, Avenula versicolor, Carex kitaibeliana, Cerastium alpinum subsp. lanatum, Cetraria islandica, Festuca airoides, F. riloensis, Poa media, Thlaspi kovatsii, etc. are also well represented.

2. Phytocoenoses on limestone, marble or other calcareous rocks. The habitats with more or less alkaline soils are of more restricted distribution in Bulgaria but the richness of the phytocoenoses and their floristic diversity is much higher. In such conditions the Siberian juniper forms phytocoenoses with the participation of Carex kitaibeliana, Daphne blagayana, D. oleoides, Dryas octopetala, Festuca balcanica, F. penzesii, F. pirinensis, Iberis sempervirens, Koeleria eriostachya, Sesleria latifolia, S. rigida, etc. In many places, the anthropogenic impact has caused the formation of shrub-herbaceous complexes in the areas of distribution of the Siberian juniper. Presently the species is very successful and expands its area of distribution.

Characteristic taxa.

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

Conservation importance. The habitat is very important for the maintenance of the biodiversity in the country. The habitat also plays a role for soil formation and protection, and water protection. The rare species Lathyrus linifolius occurs in this habitat type.

Threats. The juniper phytocoenoses are the communities that are most often set on fire to increase pastures. In the places where the projective cover of the juniper is relatively low there is a good possibility for the growth of herbaceous species and these communities are relatively good pastures.

Conservation measures taken. The habitat is included in Annex № 1 of BDA. Many of its localities are within the borders of protected areas – Rila, Pirin and Central Balkan National Park, vitosha Nature Park, etc. and in sites from the European Ecological Network NATURA 2000.

Conservation measures needed. Monitoring of the habitat and effective implementation of the legal regulations related to protected areas.

References. Meshinev et al. 2000; Roussakova 2000.

Author: Veska Roussakova


Mountain scrub of Siberian juniper (Juniperus sibirica) (distribution map)