About the Boreal Forest
The boreal forest is the largest forested biome on Earth, covering 17 million km2 of the Northern Hemisphere, and accounting for approximately one third of Earth's total forest area. Globally, the northern and southern boundaries of the boreal forest are associated with the Arctic air mass, which extends southerly in wintertime to define the southern most extent of the boreal forest, and shrinks northward during summer to delineate the boundary between boreal forest and tundra.
In Alaska, boreal forest occupies some 60-70% of the land area, with tundra and coastal coniferous forest making up the remainder. Approximately 32%, or 42.8 million ha, of the total 137 million ha that make up the interior Alaska boreal ecoregion is forested, of which >60% is dominated by black spruce (Picea mariana). The remainder is complex mosaic of grasslands, shrublands, bog and fen meadows, shrub and sedge tundra, and open water, with rock outcrops, snow and ice at high elevations.
From Nowacki G.J., P. Spencer, T. Brock, M.D. Fleming, and T. Jorgenson. 2001. Ecoregions of Alaska and Neighboring Territories