Temporal and Spatial Distribution of Trees in Subalpine Meadows of Mount Rainier National Park, Washington, USA

Rochefort, Regina; Peterson, David

Tree establishment patterns vary considerably at different locations in the subalpine zone of Mount Rainier National Park, with substantial temporal variation in regeneration of subalpine fir (Abies lasiocarpa). Recruitment in subalpine meadows has been continous on the west side of Mount Rainier, since about 1930, but has occurred in short, discrete periods on the east side. Variation in snowpack from west to east on the mountain has a substantial impact on climatic factors that limit tree establishment. Warm, dry summer climate faciliates tree establishment on the west side where snowpacks are generally very hight; cool, wet summer climate enhances tree establishment on the east side where snowpacks are lower. Density of tree establishment is significantly greater in heath-shrub vegetation than in other vegetation types. Within heath-shrub vegetation types, tree establishment is highest at lower elevations, on topographic convexities, and in plant communities dominated by Phyllodoce empetriformis. Survival of subalpine fir seedlings during the first three years after germination is significantly greater in heath-shrub vegetation than other vegetation types. If the climate becomes warmer and drier during the next century, continued rapid regeneration of trees can be expected in subalpine meadows on the west side of Mount Rainier. This may result in displacement of wildflower meadows that are an attraction for park visitors. A better understanding of climatic and environmental limitations on tree establishment will assist resource managers in developing sound management strategies for subalpine ecosystems.

Temporal and Spatial Distribution of Trees in Subalpine Meadows of Mount Rainier National Park, Washington, USA

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