Phytogeography boundaries between Stone-birch and White-birch forests in the North of the Koryak Region

The distribution boundaries of the two birch species communities: Stone-birch (Betula ermanii Cham.) and White birch (Betula platyphylla Sukacz) forests have been firstly reliably established for the North of the Koryak Region. The remote sensing data, aerial observations, original relevés, and itinerary research data were used. A map of the Stone-birch and White-birch forests allocation in the mainland part of the Koryak Region was compiled. It was shown that Stone-birch groves were found in relatively warmer and wetter areas adjacent to the Bering Sea coast. They occupy Southern and South-Eastern slopes of the Koryak Upland spurs; whereas White birch forests are common in the continental districts. They are found in the valleys of the rivers Penzhina, Talovka, Belaya, Oklan, Apukvayam, on the Penzhinskiy Ridge slopes. Stone-birch forests do not occur North of 62° northern latitude, do not overcome the boggy depression of Parapolsky Dale, and do not occur to the West of 167° 30' eastern longitude. The natural phytogeographical boundary between the areas of the two birch formations are the Southern and South-Eastern spurs of the Koryak Upland.