The moose, Alces americana, in British Columbia reaches its greatest populations in the young second growth forest areas. Numbers decrease as the forest approaches its climax stage. The decline in population is known to be mainly the result of malnutrition.The present study of three stages in forest succession growing under virtually identical conditions of soil and climate has concerned itself with quantity of available palatable browse; carotene and ascorbic acid content of available palatable and unpalatable trees and shrubs; and with determination of values for moisture, protein, carbohydrate, ether extractives, and total mineral content. Most of the analyses are confined to the winter dormant period.It is determined that the forest changes studied involve a reduction in quantity of palatable browse to about one-third; that there is an increase of carotene values and possibly of total mineral content in the vegetation on more advanced forest areas, but that in ascorbic acid content, ether extractives, total carbohydrates, and proteins the vegetation upon the younger forest areas is superior to that on the older areas.It is concluded, therefore, that the declining carrying capacity noted in a forest approaching its climax stage results from decreases in both the quantity and quality of food produced.It is further concluded that the most desirable winter range for moose is one upon which there is a variety of palatable species, predominantly in an early stage of growth, but with an intermixture of older forest stands bearing palatable coniferous trees.