Dyrness, C. T.; Franklin, Jerry F.; Moir, W. H. 1974. A preliminary classification of forest communities in the central portion of the western Cascades in Oregon. Coniferous Forest Biome Bull. 4. Seattle, WA: University of Washington. 123 p.
Forest communities in the central portion of Oregon's western Cascadesare arrayed along moisture and temperature gradients. With the aid ofreconnaissance data and a computerized ordination technique, 23 forestcommunities have been provisionally recognized in two distinct forest
zones, the Tsuga heterophylla (300 to 1050 m in elevation) and the
Abies ar?abilis (1050 to 1550 m). The location of these zones is largelya function of temperature (elevation), while distribution of individualcommunities within a zcne is controlled mainly by moisture availability.Eleven climax or near-climax associations and three seral communitieswere recognized within the Tsuga heterophylla zone. Associations rangefrom the Pseudotsuga/Holodiscus on very dry sites to the Tsuga/Polystichum-Oxalis on wet sites. In the Abies amabilis zone, nine units were identi-fied--seven climax or near-climax associations and two seral communities.Driest habitats in the zone are occupied by the Abies--Tsuga mertensiana/Xerophyllum association and wettest sites support the Chamaecgpari/Oulopanax association. Characteristics of all 23 forest communities aredescribed and relationships among them are discussed.