Rates of Tree Growth and Forest Succession in the Anchorage-Matanuska Valley Area

Abstract

Results of vegatation study by U.S. Army Map Service in summer 1955 in the area 61 07-45 N. approx. 149-150 W, from sea level to tree line at 1,500-2,000 ft. Eight principal forest cover types were distinguished. Sixty-five test plots were laid out, in which trees were counted, diameters and heights measured, and ages determined. Most important factors controlling distribution of species are altitude, drainage, fires, regenerative ability of species after fires, frequency of flooding; soil type and surficial geology are relatively unimportant. Growth rate depends on amount of sunlight and drainage; cottonwood and aspen have highest rates, birch and white spruce lower, black spruce lowest. Mixed birch-white spruce forest is generally self-perpetuating.