From Wikipedia; please see the article if you're interested in further information.

The Mixed Forest
The mixed and deciduous forest belt is triangular, widest along the western border and narrower towards the Ural Mountains. The main trees are Oak and Spruce, but many other growths of vegetation such as ash, aspen, birch, hornbeam, maple, and pine reside there. Separating the taiga from the wooded steppe is a narrow belt of birch and aspen woodland located east of the Urals as far as the Altay Mountains. The roe deer, wolf, fox, and squirrel are very common.