摘要：The aim of this study has been to provide a better spatial view of the distribution of different forest types and other major vegetation types and of their relationship to the landscape. The study is based on new topographic maps, interpretation of Landsat‑1 imagery, aerial photographs and field controls. A new four‑colour vegetation map on a scale of 1 : 200 000 has been produced. Special attention has been given to the vast damage to birch forests caused by the butterfly larvae of Oporinia autumnata. The total mapped area is 13 207 km2 and the damaged area 1 210 km2. Reafforestation of the damaged areas has been hampered so badly that to some extent they may form new treeless tundra areas. On the basis of the literature the formation of forest limits has been discussed. It has been concluded that the most important factors affecting the formation of forest limits are different climatic and biotic hazards that occur occasionally.
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