Home – Home – Jornals – Contemporary Problems of Ecology 2013 number 6

The applicability of the notion of ecotone to the ornithofauna of forest-tundra near the Ob river is considered. Within the left-bank territory of the Ob, from the flood-plain and the Ob Bay to the Polar Urals and the eastern coast of the Baydarata Bay, from northern taiga to shrubby tundra, nesting of 177 bird species was proved by 2009. Nested avifauna of forest-tundra at the latitude of the Polar circle includes 140 species. For the northern extreme end of the taiga (64–65° n. l.), nesting of 151 species is known; for the shrubby tundra of Middle Yamal (68–69° n. l.), nesting of 73 species was established. The taiga-related species penetrate into the southern forest-tundra through flood-plain forests and the taiga islands of the placore, into the middle and northern forest-tundra only through flood-plain forests gradually loosing a part of the listed composition. Enrichment of the fauna of forest-tundra by the birds of tundra occurs at the placore: in the regions of tundras, tundra-like bogs and in depressions of forest-tundra lakes. The abundance of birds in the main biotopes in forest-tundra is somewhat lower than in northern taiga, and higher than in southern tundra. It is created by birds with large ranges. Open woodlands of the placore that distinguish forest-tundra from taiga and tundras for the majority of birds are the tundra, but richer in invertebrates due to the developed shrub stratum. At present, the forest-tundra does not have its own avifauna. It is likely to be forming because the species diversity of nesting birds increases, and the species having the maximum of population density in forest-tundra have appeared. However, at present there is no pronounced cumulative effect of faunas superposition.