G. Forests

Forests of Black pine (Pinus nigra subsp. pallasiana)

Relationships with habitat classifications. EUNIS: G3.5618 Rhodopi Pallas΄ Blackpine forests, G3.5619 Balkan Range Pallas΄ Blackpine forests, G3.561A Moeso-Macedonian Pallas΄ Blackpine forests; PAL. CLASS.: 42.6618 Rhodopi Pallas΄ Blackpine forests, 42.6619 Balkan Range Pallas΄ Blackpine forests, 42.661A Moeso-Macedonian Pallas΄ Blackpine forests; HD 92/43: 9530 *(Sub-) Mediterranean pine forests with endemic black pines; Bondev (1991): 46 Mixed Mizian beech (Fagus sylvatica subsp. moesiaca) and Black pine (Pinus nigra) forests, 65 Black pine (Pineta nigrae) forests, 66 Black pine (Pinus nigra) and Balkan durmast (Quercus dalechampii) forests, 67 Black pine (Pinus nigra) and Aquatic hornbeam (Ostrya carpinifolia) forests.

Conservation status. BDA, BC, HD.

Category. Vulnerable [VU – A1, 2 B2 E2 F2 G2 1 L2].

General characteristics. The Black pine (Pinus nigra) occurs in Central and South Europe and Southwest Asia. On the Balkans, including Bulgaria, the subspecies Pinus nigra subsp. pallasiana occurs. Its communities belong to the Mediterranean vegetation type in Bulgaria. The species is xerothermic with large range of altitude, from 400 up to–1800 m alt. Presently, the main part of the Black pine forests in Bulgaria occur between (600) 800 and 1300–1500 m alt., mainly in steep areas. The forests occur in different vegetation belts, from the xerothermic oak belt, through the mesophilic hornbeam-beech forests up to the microthermic coniferous forests and hence fall into different climatic and phyto-geographical territorial subdivisions. They occur from Slavyanka and East Rhodopi Mts to the Forebalkan. These coenoses occur mostly in Rhodopi, Vlahina and Pirin Mts. and to a more limited extent in Slavyanka, Rila, Osogovo Mts., the low mountains of West Bulgaria, the Balkan Range and Forebalkan. They occur in the three climatic zones in Bulgaria: moderate continental, transitional and continental-Mediterranean. Although the ecological features of the Black pine coenoses presupposes their affiliation to the xerophytic vegetation type, the exposure of the slopes they cover can be different but mainly southern, sometimes with an eastern component. The slopes can be very steep. Single trees occur also on vertical rocks and the species shows pioneer features. The Black pine coenoses prefer alkaline rocks. In the northern parts of their distribution the calcareous rocks are obligatory while in the southern parts of the country the Black pine forests can occur on other type of bedrocks; therefore the soil type is mainly humus carbonate Rendzic Leptosols, but the Black pine coenoses can grow also on Cambisols, especially when they are on silicate bedrock. The soils are often eroded, poorly developed and thin. The humidity can vary throughout the vegetative season from low to relatively moderate.

The Black pine coenoses are fragments of older (relic) vegetation. Well-preserved parts of the relic forests that are with preserved composition and structure of the autochthonous vegetation are very rare. Some trees can be 150–200 years old. Apart from the autochthonous coenoses also secondary ones exist. The Black pine coenoses can be monodominant (the prevailing part of the phytocoenoses), or mixed with various coniferous and deciduous tree species that have xerothermic or meso-xerothermic characteristics. Fragments of the ancient, widely distributed Black pine forests occur mainly in the southern parts of Bulgaria at lower altitudes (Haskovo and Kardzhali districts, Dobrostan massif). Parts of them are monodominant, in others the xerothermic oaks Quercus frainetto and Q. pubescens, the Oriental hornbeam Carpinus orientalis, and Acer campestre, Fraxinus ornus, Pyrus pyraster, Sorbus torminalis etc. occur with different abundances. Cornus mas, Corylus avellana, Cotinus coggygria, Syringa vulgaris occur in the shrub synusium. The participation of Genista carinalis, G. rumelica, Juniperus oxycedrus etc. provides the Mediterranean outlook of these forests. The herbaceous vegetation is dominated by Brachypodium pinnatum, B. sylvaticum, Festuca heterophylla, Melica uniflora, Poa nemoralis etc. The rare and protected species Anthemis rumelica, Carduus thracicus, Fritillaria pontica, Verbascum roripifolium, V. rupestre etc. also occur. Most of the Black pine coenoses are not in good condition as a result of the anthropogenic pressure. Nowadays from the widely distributed in the past Black pine forests only small islands among the broad-leaved vegetation have remained.

As the altitude increases (800–900–1350 m) the floristic diversity in the Black pine coenoses increases. Quercus dalechampii, Fagus sylvatica, Carpinus betulus,more rarely Abies alba, Fraxinus excelsior, Picea abies,and in some places Abies alba subsp. borisii-regis are codominants or simply occur in the Black pine forests and give a more mesophytic outlook. The composition of the shrub synusium does not change much (Carpinus orientalis, Clematis vitalba, Cornus mas, Corylus avellana, Cotinus coggygria, Daphne mezereum, Juniperus communis, J. oxycedrus, Rubus spp.,but its abundance is very low. Brachypodium pinnatum, B. sylvaticum, Calamagrostis arundinacea, Hedera helix, Sesleria latifolia, Trifolium alpestre etc. constitute the herbaceous vegetation, together with some mesophytes like Cruciata glabra, Oxalis acetosella, Sanicula europaea, Viola canina etc. In stony places in the ravines, mainly in Southwest Bulgaria, the Black pine makes coenoses with Ostrya carpinifolia. Cephalanthera rubra, Poa nemoralis, Scabiosa rhodopensis, Sesleria latifolia etc. occur in the herbaceous layer.

The most widely distributed mixed coenoses are these of the Black pine with Quercus dalechampii. Most probably the latter has replaced Рinus nigra in many places. Such process has taken place in some parts of the country (Gabra Managed Nature Reserve).

In Pirin and Slavyanka Mts., Pinus heldreichii participates in the composition of the Black pine coenoses and at higher altitudes its abundance is higher than this of the Black pine. The herbaceous layer includes mainly drought-resistant species like Brachypodium pinnatum, Calamagrostis arundinacea, Festuca dalmatica, F. penzesii, Sesleria coerulans etc. Large populations of Arctostaphylos uva-ursi develop in the Black pine forests in Pirin National Park and in other parts of Bulgaria.

In some coenoses, even on limestone, when the tree layer is very dense, almost no shrub species occur (only single shrubs of Crataegus monogyna, Juniperus communis etc. can be registered). The herbaceous layer includes mainly Calamagrostis arundinacea and Vaccinium myrtillus with the participation of Asperula cynanchica, Brachypodium sylvaticum, Briza media, Carlina vulgaris, Chamaespartium sagittale, Cruciata glabra, Fragaria vesca, Hypericum cerastoides, Lerchendfeldia flexuosa, Plantago subulata, Primula veris, Pteridium aquilinum, Rosa myriacantha, Rubus saxatilis, Sieglingia decumbens, Thymus spp., Vaccinium vitis-idaea, Viola canina.

The herbaceous vegetation on silicate bed rock has similar features with the forests of Quercus dalechampii and Pinus sylvestris: Calamagrostis arundinacea, Dactylis glomerata, Genista carinalis, Hieracium praealtum, Luzula luzuloides, Poa nemoralis, Vaccinium myrtillus. Vaccinium myrtillus and V. vitis-idaea dominate at higher altitudes.

The associations of the black pine are included in class Erico-Pinetea, order Erico-Pinetalia, allience Erico-Pinion with sub-alliance Orno-Pinenion pallasianae. One of the associations of the black pine forests in Bulgaria is Seslerio latifoliae-Pinetum nigrae.

Characteristic taxa.

Distribution in Bulgaria. Slavyanka, Pirin, Rhodopi, Rila, Osogovo, Vlachina Mts. and some heights in West Bulgaria and West and Central Balkan Range and Forebalkan, between 400 and 1800 m alt.

Conservation importance. The Black pine forests are an important edaphic and hydrological factor. They are relic phytocoenoses in the plant vegetation in Bulgaria. Some rare and protected plants, especially in Rhodopi Mts., occur in them: Anthemis rumelica, Carduus thracicus, Fritillaria pontica, Pulsatilla halleri subsp. rhodopaea, Scabiosa rhodopensis, Verbascum roripifolium, V. rupestris etc. and in Pirin Mts.: Centaurea achtarovii, Cephalanthera longifolia, Kernera saxatilis,etc. Fungi of conservation importance also occur – Clavariadelphus ligula, C. truncatus, Clitocybe vermicularis, Clitopilus giovanellae, Geastrum quadrifidum, Gyromitra gigas, Hygrophorus erubescens, Limacella glioderma, Omphaliaster asterosporus, Pholiota lucifera, Pisolithus arhizos, Sarcosphaera coronaria, Tricholoma colossus, T. facale. The Black pine participates in rare coenoses with Abies alba subsp. borisii-regis.

Threats. The Black pine is used as a construction material, for resin, and by the local people for the production of pine splinters. It has ornamental features as well. The habitats of this species have been strongly reduced. The forests have been destroyed as a result of various economic activities (including unregulated logging) or have been replaced by Quercus dalechampii, Fagus sylvatica, etc. as a result of natural successions. Parts of the coenoses have been turned into open (sparse) forests.

Conservation measures taken. The habitat is included in Annex № 1 of BDA and is of conservation priority. Parts of the coenoses of Pinus nigra subsp. pallasiana are within protected areas: Bayuvi Dupki – Dzhindzhiritsa, Chervena Stena, Kazanite and Alibotush Strict Nature Reserves; Gabra, and Boraka Managed Nature Reserves, Pirin and Central Balkan National Parks, etc. and in sites from the European Ecological Network NATURA 2000.

Conservation measures needed. Inventory and monitoring of the state of the habitat. Strict implementation of the legal acts and regimes for the national parks and norms for nature-friendly forest management.

References. Velchev et al. 1989; Vlassev 1966; Gussev et al. 2005a; Nikolov & Valchev 1997, 1998; Valchev & Nikolov 1993.

Authors: Veska Roussakova, Vladimir Valchev

Forests of Black pine (Pinus nigra subsp. pallasiana) (distribution map)