The birds of Pasvik / E. I. Khlebosolov, O. A. Makarova, O. A. Khlebosolova [et al. ; English transl. Nikita Chernetsov]. - Ryazan : Golosgubernii, 2007. - 175 с. : ил., портр.

E.l. Khlebosolov The mountain birch forest belt occupies a large area in the lower flow o f the Pasvik. low shrub consists o f cowberries and bilberries, sometimes crystal tea ledum and bog whortleberry. Between mosses, plants o f the genera Pleurozium and Hylocomium are most common. Primary birch forests occur on the banks o f rivers and streams. Secondary birch forests grow in cleared plots. Birch mainly forms the second layerage in mixed stands. Apart from white birch, occurrence o f silver birch (Betula pendula Roth) is known, but it does not form large stands. In wetter places along streams and on the banks o f the Pasvik river stands o f white alder (Alnus incana ( L.) Moench s. I.) and aspen (Populus tremula L.) occur among birches. In galleries in the herbs layer o f birch forests ferns and dwarf cornel (Chamaepericlymenum suecicum L.) occur. In the tundra forest white birch is the main tree that forms sparse growths. However some authors (Ramenskaya 1972) treat it as a separate species Betula tor- tuosa Ledeb. The tree height varies from 5—6 in the southern tundra forest down to 1 m in the north. Under the canopy o f white birch grow Arctic birch, different wil­ low species, Siberian juniper, northern mountain-ash Sorbus aucuparia L. subsp. glabrata (Wimm. & Grab.) Hayek. The ground cover is formed by lichens, green moss and subshrubs. In higher hills altitudinal belts are pronounced. In northern taiga forest grows up to ca. 200 m a.s.l. These are mainly pine trees with spruce and birch admixed and black crowberry, red bilberry and bilberry in the undergrowth. Higher up the forest becomes thinner, the proportion o f birch increases. It is gradually replaced by crooked birch forest, and from 300 m a.s.l. mountain tundra starts. Most common 19