From introduction: 'The boreal forest of Alaska represents the northwestern portion of a great transcontinental forest belt that extends through more than 110 degrees longitude, from Newfoundland and the Labrador coast in Canada to the limits of tree growth on the Seward Peninsula in Alaska. The boreal or interior forest of Alaska is characterized by white spruce (Picea glauca [Moench] Voss) and black spruce (P. mariana [Mill.] B.S.P.). Tamarack (Larix laricina [Du Roi] K. Koch) is encountered only occasionally and is relatively unimportant. Although the forest is dominantly coniferous, several hardwood species are distributed throughout and locally may form extensive pure stands. These are Alaska paper birch (Betula papyrifera Marsh. var. humilis [Reg.] Fern. & Raup); Kenai (B. papyrifera Marsh. var. kenaica [W. H. Evans] A. Henry); quaking aspen (Populus tremuloides Michx.); and balsam poplar (P. balsamifera L.).'