Title SNOWBRUSH, CEANOTHUS VELUTINUS DOtJGL., ITS ECOLOGY AND ROLE IN FOREST REGENERATION IN THE OREGON CASCADES

Abstract approved (Major professor) The ecological and silvicultural importance of snowbrush, Ceanothus velutinus, in the areas west of the summit of the Oregon Cascades was studied. Particular attention has been given its nitro-gen-fixing ability under both field and greenhouse conditions. On west slopes of the Oregon Cascades snowbrush occurs above 2, 500 feet elevation, Coiitrary to its permanent presence in some climax associations of the central Oregon, it may occur after an ab-sence of 300 to over 500 years in the area of this study. The germ-ination of the seed, which had accumulated during the brief lifetime of snowbrush stands in the duff and upper layer of the mineral soil, is stimulated by fire followed by winter stratification. Extensive areas have been occupied by snowbrush following logging and slash burning