High elevation vegetation of the Enchantment Lakes Basin, Washington

摘要

The vegetation of the Enchantment Lakes Basin, which is located at and above timberline on the slopes of Mount Stuart, Washington, was examined by classification and ordination methods. A vegetation map relates the 21 recognized community types to physiographic and topographic features. Vegetation was divided into plots with and without trees. The 11 forested communities include those dominated byLarix lyalliiandCassiope mertensianaon moist slopes,L. lyalliiandPhyllodoce glandulifloraon steep north-facing slopes,Abies lasiocarpaandVaccinium inyrtilluson low elevation, moist sites, and several communities dominated byPinus albicaulison dry, exposed slopes. The 10 alpine communities include dry fell-fields dominated byLupinus lepiduswith a variety of forbs, communities dominated byCassiope mertensianaandPhyllodoce glandulifloraand byP. empetriformis, and lush and wet meadow communities dominated byLupinus polyphyllusandCarex nigricans. These communities are related to those identified by other workers in the Pacific Northwest. Keys to the vegetation of this area are presented. Indirect gradient analysis using reciprocal averaging revealed both vegetation and species patterns. In the subalpine, moisture appears to be the dominant operational gradient, while inferred temperature is a secondary factor. In the alpine vegetation, a combined gradient of moisture and exposure is indicated by reciprocal averaging. Special ordinations derived from reciprocal averaging reflect these interpretations and identify indicator species for particular habitats in both subalpine and alpine. The patterns are summarized with a mosaic diagram. The use of multivariate methods provided means to summarize primary survey data quickly and efficiently. The pattterns thus revealed are comparable to other studies in the Pacific Northwest and thus engender confidence in the use of indirect gradient analysis as a valuable tool for primary survey in these ecosystems. A vegetation map, keys to vegetation types, community and species patterns, and the relationship between classifications and ordinations emerged from this study.