33G3

G. Forests

King Boris’s fir (Abies alba subsp. borisii-regis) forests

Relationships with habitat classifications. EUNIS: G3.171 King Boris΄s fir forests; PAL. CLASS.: 42.171 King Boris΄s fir forests; HD 92/43: 9270 Hellenic beech forests with Abies borisii-regis.

Conservation status. BDA, BC, HD.

Category. Endangered [EN – A1, 2 B1, 2 C2 D2 F2 H2 I].

General characteristics. Abies alba subsp. borisii-regis, called also the Pointed-needle fir, has been classified as subspecies in 1925. It is a complex introgressive hybrid between Abies cephalonica and Abies alba, occurring in the southeastern parts of the distribution area of Abies alba in the transitional conditions between the Mediterranean and continental climate. The Balkan endemic Abies alba subsp. borisii-regis also occurs outside Bulgaria, mainly in Greece.  It is found in the Rila-Rhodopi mountain massif (Belasitsa, Slavyanka, Pirin, Rila and Rhodopi Mts.). The altitude at which the subspecies occurs varies between 900 and 1700 (1800) m alt. However, this subspecies is very rarely an ediphicator in the present vegetation cover of the country. It occurs mainly as single trees or small groups in the beech forests or forests of other coniferous species. In some places it forms a second layer (mainly in forests of Pinus nigra, P. sylvestris and Fagus sylvatica). Therefore, despite the fact that the species is widely distributed, the habitat is extremely rare in Bulgaria. If the negative anthropogenic activities stop the future syndynamics of some phytocoenoses of Abies alba subsp. borisii-regis can result in changes of their composition so that Abies alba subsp. borisii-regis can become a dominant on larger areas.

Although the alkaline rocks dominate, the acidity of the soil is not of vital importance for the development of Abies alba subsp. borisii-regis. The soils are humus-carbonate. In some places even when the soil develops on calcareous rock it can be Cambisols  medium thick or shallow. The slopes are sunny even when they have a northern exposure, but the air and soil humidity is moderate. The slope is mainly moderate 10–20 .

The phytocoenoses of Abies alba subsp. borisii-regis, like the remaining forest vegetation in the mountains of Bulgaria, have been subjected to strong anthropogenic pressure. This caused their destruction, proved by the existence of single, very old trees of Abies alba subsp. borisii-regis (some of them 80 cm in diameter and over 150 years old) that occur both in forests dominated by this species or in coenoses with other tree ediphicators. That the ages of the phytocoenoses of this species are different is a positive fact. Together with good seed reproduction rate they guarantee the persistence of these coenoses.

The floristic composition of the different coenoses is different and depends to a certain degree on the specificities of the local flora. Hence, in Rhodopi Mts., species with different ecology and areas of distribution grow together. Apart from Abies alba subsp. borisii-regis in the tree layer occur also Fagus sylvatica, Pinus nigra, P. sylvestris etc. Clematis vitalba, Crataegus monogyna, Juniperus communis, Lonicera xylosteum, Ostrya carpinifolia occur in the understory. The coenotic diversity is determined also by the sympatric existence of mesophytes, xerophytes, skiophytes and heliophytes in the ground layers and they have different projective cover (in some places 20–30%, in other even higher). The following species occur: Aremonia agrimonoides , Asplenium trichomanes, Brachypodium sylvaticum, Buglossoides purpurocaerulea, Campanula rapunculoides, Carlina vulgaris, Cephalanthera longifolia, C. rubra, Clinopodium vulgare, Cruciata laevipes, Cystopteris fragilis, Dactylis glomerata, Dentaria bulbifera, Digitalis lanata, Euphorbia amygdaloides, E. cyparissias, Festuca nigrescens, Fragaria vesca, Hypericum perforatum, Luzula forsteri, Mycelis muralis, Primula elatior, Salvia glutinosa, Sanicula europaea, Stachys germanica, Stellaria nemorum, Veronica chamaedrys etc.

Some of the coenoses in Slavyanka Mts. occur in the belt of Pinus heldreichii and it occurs in their composition together with the Common beech. They occur mainly below Tsarev Peak at about 1700 m alt.

The climate changes hardly have unidirectional impact on the development of Abies alba subsp. borisii-regis. However, its rapid development as a second tree layer in the forest coenoses will contribute for the expansion of its habitat.

Characteristic taxa.

Distribution in Bulgaria. Slavyanka, South Pirin, Central and West Rhodopi, Southwest Rila Mts.; at 900–1800 m alt. The species occurs also in Belasitsa Mts. but in small groups in beech coenoses.

Conservation importance. The communities are very rare in the contemporary vegetation cover of Bulgaria. They have strong soil formation and soil protection functions for the forest vegetation. Some species protected by law participate in these coenoses like Alyssum stribrnyi.

Threats. Wood felling (the phytocoenoses are a source for wood extraction), wind storms, fires, parasites.

Conservation measures taken. The habitat is in Annex №1 of BDA. Part of the localities are within Chervena Stena and Alibotush Strict Nature Reserves as well as in sites from the European Ecological Network NATURA 2000.

Conservation measures needed. Detail phytocoenotic study and mapping of the plant communities; long-term monitoring. Protection of the coenoses in which Abies alba subsp. borisii-regis currently forms the second layer and such in which the species occurs with few but old trees with large diameter.

References. Andreev & Nikolov 1985; Vassilev 1983; Meshinev 1995.

Author: Veska Roussakova


King Boris’s fir (Abies alba subsp. borisii-regis) forests (distribution map)