25G1

G. Forests

Birch (Betula pendula) forests

Relationships with habitat classifications. EUNIS: G1.9135 Illyro-Moesian Montane birch woods; PAL.CLASS.: 41.B35 Illyro-Moesian Montane birch woods; Bondev (1991): 23 Birch (Betuleta pendulae) forests replacing Spruce (Picea abies) and Silver pine (Pinus sylvestris) forests, 43 Birch (Betuleta pendulae) forests replacing Ordinary beech (Fagus sylvatica) and White fir (Abies alba) forests.

Conservation status. None.

Category. Nearly Threatened [NT – B1 C1 D2 E2 F1 G1 H1 J L1].

General characteristics. The habitat encompasses natural pure and mixed forests dominated by Betula pendula and with the participation of Picea abies, Pinus sylvestris, Abies alba, Fagus sylvatica, Pinus peuce and Populus tremula. They are fragmented and occur in almost all Bulgarian mountains. They develop mainly on Cambisols. The White birch is a pioneer species that occurs naturally in groups or as single trees in mesophilic coniferous or beech forests. As a result of natural or anthropogenic successions, it forms pure and mixed communities replacing the destroyed or disrupted primary forests. Due to its good reproductive potential the birch occupies fast new areas where the autochthonous vegetation has been destroyed by wind throws, snow throws, fires and avalanches. In some cases it also occupies abandoned pastures and meadows. Often the birch is a major ediphicator accompanied by spruce, beech or fir. The herbaceous layer includes mesophytic species typical for the coniferous and beech forests: Calamagrostis arundinacea,Chamaenerion angustifolium (= Epilobium angustifolium), Deschampsia flexuosa,Epilobium montanum, Euphorbia amygdaloides, Luzula luzuloides, Poa angustifolia, P. nemoralis, Rubus idaeus, Senecio nemorensis, Trifolium medium, Vaccinium myrtillus, Veronica urticifolia.

The pioneer birch forests in Bulgaria have not been studied syntaxonomically. In other European countries they belong to the alliance Sambuco-Salicion and class Epilobietea angustifolii. According to some contemporary studies it is more suitable to affiliate the the alliance mentioned above to the class Brachypodio pinnati-Betuletea pendulae.

Characteristic taxa.

Distribution in Bulgaria. The birch forests cover about 7000 ha in Rila-Rhodopi massif, the Balkan Range, Ossogovo and Plana mountains, from 750–800 up to 1750–1850 m alt. They are most widely distributed in Rhodopi Mts. and Etropolski Mts. (Central Balkan Range).

Conservation importance. Some vascular plants (Lathraea rhodopaea, Pinus peuce, Pyrola media) and fungi (Clavicorona pyxidata, Hymenogaster luteus, Lactarius spinosulus ) of conservation significance occur in the birch forests.

Threats. Natural successions that cause the replacement of the birch communities by spruce, Scots pine and beech forests; unregulated felling.

Conservation measures taken. Part of the birch forests are within the borders of protected areas like Central Balkan National Park, Belikata Protected Site and in sites of the European Ecological Network NATURA 2000.

Conservation measures needed. Detailed phytocoenological studies, mapping and monitoring, improved guarding system in the forests and implementation of suitable forestry practices.

References. Exner & Wilner 2004; Iliev 1988; Penev et al. 1969.

Author: Marius Dimitrov


Birch (Betula pendula) (distribution map)