16F2

F. Shrub communities

Dwarf pine (Pinus mugo) mountain scrub

Relationships with habitat classifications. EUNIS: F2.48 Balkan-Rhodopide Pinus mugo scrub; PAL. CLASS.: 31.5 Balkan-Rhodopide Dwarf mountain pine scrub; HD 92/43: 4070 *Bushes with Pinus mugo and Rhododendron hirsutum(Mugo-Rhododendretum hirsuti); Bondev (1991): 3 Scrub community (Pineta mugi) partly mixed with potential scrub (Alneta viridis, Saliceta waldsteinianae etc.) and secondary srcub (Junipereta sibiricae etc.), dwarf scrub (Vaccinieta vitis-idaeae etc.) and grass (Nardeta strictae, Festuceta validae etc.) communities.

Conservation status. BDA, HD.

Category. Vulnerable [VU – A1, 2 B1 C2 F2 G2 I L3].

General characteristics. The Dwarf pine (Pinus mugo) is an alpine (Central European and South European) species. Most often it is a shrub (up to 4–5 m high, with semiprocumbent, ascending branches) or a small tree. It is indifferent to humidity, temperature and acidity of the bedrock and the soil. The Dwarf pine communities occur mostly above the timberline – between (1800–1900) 2000–2100 and 2500 (2600) m alt. In Bulgaria the Dwarf pine is an edificator and dominant species in the phytocoenoses that outline the upper subalpine belt of Rila and Pirin Mts. at a vertical range of 500–600 m alt. These coenoses cover restricted areas in West and Central Balkan Range. In Vitosha, Rhodopi and Belasitsa Mtss the Dwarf pine occurs with single shrubs or in small groups. In the past the phytocoenoses of the Dwarf pine used to completely cover these areas while the herbaceous and other shrub and small-shrubs coenoses were more limited. People exploited this vegetation in an unregulated manner thus changing the ratio between the different groups of phytocoenoses. The Dwarf pine has more or less restored its original distribution and this process continues in the present vegetation cover. Part of this vegetation is still of primary origin, because the Dwarf pine behaves as a pioneer species and occurs on rocks and stone fields with large rocks. The specificity of the bedrock (limestone or silicate) as well as the soil type does not restrict the formation of the Dwarf pine phytocoenoses. The soils are mainly Cambisols and more rarely more shallow Leptosols (lithic, umbric or rendzic). The Dwarf pine is an aggressive pioneer species and behaves like a hasmophyte on steep and vertical rocks without soil cover. The soil humidity varies considerably, but more often it is good. The mesophilic phytocoenoses are most frequent but also hygrophilis and xerophilic coenoses exist. The exposure and slant of the areas covered by these coenoses also do not play decisive role in the development of the Dwarf pine communities. The covered areas are slopes with various slant and ridges, depressions or elevated parts of the relief. Everywhere the monodominant phytocoenoses of the Dwarf pine prevail. The participation of other tree species (Picea abies, Pinus peuce, P. sylvestris, Salix caprea, Sorbus aucuparia etc.), especially near the timberline is very limited. The abundance of shrubs (Rubus idaeus, Alnus viridis, Salix waldsteiniana) also varies. Only the Siberian juniper (Juniperus sibirica) participates almost in all Dwarf pine coenoses and very often replaces the Dwarf pine after its destruction, thus making secondary shrub coenoses. The ground layers are well developed in most of the phytocoenoses and can be classified in two main groups according to the acidity of the bedrock and the soil. In the Dwarf pine coenoses on silicate the most widely distributed species are Homogyne alpina, Deschampsia flexuosa, Vaccinium myrtillus,and the mosses Hylocomium splendens, Pleurozium schreberi, Rhytidiadelphus triquetrus. In many places, despite the shadow casted by the shrubs, especially in lighetre places, species from the neighbouring herbaceous coenoses: Calamagrostis arundinacea, Festuca nigrescens, F. valida, Gentiana punctata, Geum montanum, Jasione bulgarica, Poa media, Sesleria comosa, Vaccinium vitis-idaea, etc. can occur. In the ground layers at relatively lower altitudes the abundance of Luzula sylvatica, L. luzuloides, Oxalis acetosella, etc. increases. On the contrary, at high altitudes, in primary Dwarf pine coenoses the small shrubs and herbs almost disappear. On the soil surface, if it exists, and on the rocks, the abundance of Cetraria islandica increases. The Dwarf pine makes coenoses also in boggy and swampy places, but this is a different habitat type (see Bog conifer forests and shrubs).

In the Dwarf pine coenoses on limestone, marble and other alkaline bedrock the species composition of the ground layers depends on the degree of the soil development – on the better developed and thicker soils are neutral or slightly acidic the dominant species is Vaccinium myrtillus. On shallow calcareous soils Vaccinium species are absent and Carex kitaibeliana, Daphne oleoides, Dryas octopetala, Festuca penzesii together with other calcicole and neutrophilic species are abundant.

The participation of some typical species from the local floras, e.g. Festuca balcanica in the Balkan Range, does not considerably change the floristic structure of these phytocoenoses compared to the ones in Rila and Pirin Mts. This is due to similar characteristics of the habitats occupied by the Dwarf pine. The great diversity of the habitats in which the phytocoenoses of the Dwarf pine have developed reflects in the existence of several subassociations within the main association Lerchenfeldio-Pinetum mugo. Two of them are in habitats that are part of the habitat type under consideration, i.e. Lerchenfeldio-Pinetum mugo typicum and Cetrarietosum islandicae. The phytocoenoses on alkaline bedrocks and soils belong to another syntaxon that has not been described yet. Near the timberline the Dwarf pine covers the meadows and can form a layer in the forest phytocoenoses that belong to other syntaxonomic units. The main part of the Dwarf pine communities are autochthonous and of primary origin. Rarely, on the border with the forest vegetation, secondary coenoses of the Dwarf pine have replaced destroyed forests.

Characteristic taxa.

Distribution in Bulgaria. Rila, Pirin, West Rhodopi, Vitosha and Belasitsa Mts., the Balkan Range; 1700–1900–2500 (2800) m alt.

Conservation importance. Very important for their water- and soil-protection functions, as an important resource for recreation purposes, maintenance of the biodiversity in various aspects. The fungi Spathularia flavida that is of conservation significance has been found in this habitat.

Threats. development oftourist infrastructure. Until recently the economic exploitation of the Dwarf pine was reduced to the minimum, but in the last years its destruction has started again. The coenoses of the Dwarf pine used to be cut down and burned for different reasons in the pats. Nowadays, they are destroyed as a result of the construction of ski tracks, tow-lifts and other tourist infrastructure.

Conservation measures taken. The habitat is included in Annex № 1 of BDA and is of conservation priority. Significant parts of the Dwarf pine communities are within protected areas – Rila, Pirin and Central Balkan National Parks and Vitosha Nature Park. Some of the most representative localities are within sites from the European Ecological Network NATURA 2000.

Conservation measures needed. Monitoring of the state of the habitat and strict implementation of the regimes in the protected areas.

References. Bondev 1959, 1991; Ganchev 1963, Penev 1939; Roussakova 2000.

Author: Veska Roussakova


Dwarf pine (Pinus mugo) mountain scrub (distribution map)