forests containing primarily birch and aspen, that is, trees with small leaves (in contrast to broad-leaved forests). They are widespread throughout the forest zone of Eastern European and the Western Siberian plains, the mountains and plains of the Far East, and the Western Siberian and Middle Siberian forest steppes. These zones form a belt of hardwood forests extending from the Urals to the Enisei River. Birch forests are much more common than aspen.
Small-leaved forests are bright and are distinguished by the variety and lushness of the herbaceous ground cover. These ancient forests were gradually forced out by the taiga; however, much later, as a result of human activities (felling of taiga forests, fires) and the rapid growth of birches and aspens, small-leaved forests are once again extensive.