THE BOREAL FORESTS OF NORTH-EASTERN EURASIA

The distribution, diversity and structure of boreal forests of monsoon Asia are reviewed. The boreal zone is circumscribed by the isotherms of 15 degrees C and 45 degrees C of Kira's Warmth Index (WI) and inclu des the territory of the Amur basin, the seashores of the Sea of Okhot sk, Kamchatka, Sakhalin and the Kuril islands. Boreal forests also occ ur on the mountains of Hokkaido, Honshu, Korea and NE China. The ocean ic sectors of the boreal zone are composed mainly of birch forests, th e marine sectors of spruce-fir forests and the continental sectors of larch and pine forests. The upper limit of the boreal forests ascends from the lowest level in the North to ca. 1500 m a.s.l. in the South o f the zone, and reaches above 2500 m in the mountains of the temperate zone. In the boreal zone the secondary forests are common. They form after fires and cutting. Volcanism is an essential factor in the fores t dynamics in the oceanic part of the region. It is suggested that as a result of global warming one may expect a strong alteration in veget ation pattern, especially in the northern and mountain areas.