Along the coast of northern Washington and southern British Columbia, the high annual precipitation supports thick temperate rain forests. Boreal forests sweep across northern North America from northwestern Alaska to Newfoundland. In this region of severe cold and heavy snowfall, winter lasts seven to eight months. However, the short growing season has dependable rainfall and many hours of daylight each day. The boreal forests are dominated by coniferous evergreens, chiefly balsam fir, black spruce, jack pine, and white spruce.
Some areas support stands of larch, which is a deciduous conifer.
Such deciduous broadleaf trees as balsam poplar, trembling aspen, and white birch grow in areas that have been burned over by forest fires. Some of the bogs are treeless. Other bogs, called muskegs, are covered by a deep mat of moss on which dwarfed conifers grow. Subarctic woodlands lie along the northern edge of the boreal forests. The climate in this region is bitterly cold, with low precipitation and an extremely brief growing season.