At subalpine elevations, the mountains support forests of red fir mixed with lodgepole pine and mountain hemlock. These subalpine forests thin out into savannas of bristlecone and whitebark pine at elevations near the timber line. Pacific coastal forests extend along the Pacific Ocean from west-central California to Alaska. The warm currents of the Pacific help give this region a mild climate the year around. Warm, moisture-filled winds from the ocean bring heavy annual precipitation.
Huge conifers dominate the Pacific coastal forests.
Forests of redwood, one of the world's tallest trees, grow along a narrow coastal strip from central California to southern Oregon. Inland from the redwoods and to the north, grow magnificent forests of Douglas-fir, Sitka spruce, western hemlock, and western redcedar. 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.