Response of Big Game Winter Range Vegetation to Fertilization

Abstract

Nitrogen and phosphorus, alone and in combination, were applied to bitterbrush (Purshia tridentata) and sagebrush (Artemisia tridentata) and three herbaceous species, beardless wheatgrass (Agropyron inerme), prairie Junegrass (Koeleria cristata), and Pacific aster (Aster chilensis). Spring applications of nitrogen significantly increased forage production of the three herbaceous species; twig growth, seed production, and percent crude protein of the leaves and twigs of bitterbrush and sagebrush were increased also. Throughout the winters of 1972-73 and 1973-74, the nitrogen-fertilized bitterbrush and sagebrush plants were used more heavily by elk than the unfertilized plots. Neither yields nor utilization were increased by phosphorus.