Slopes are steep and stream drainages are deeply incised. When established in 1948, it was unroaded virgin forest and about two-thirds remain pristine today. Broadly representative of the rugged mountainous landscape of the Pacific Northwest, it contains excellent examples of the region's conifer-dominated forest and stream ecosystems. Intra-site climatic variation is typical of mountainous terrain. Temperature varies with elevation, aspect and topographical shading.
Temperature inversions are common.
Precipitation generally increases with elevation as does the proportion that falls as snow. Regression statistics and additional notes are reported in Table 2.3. Vegetation Old-growth conifer forest with greater than 400 year old dominant trees covers about 45 percent of the Andrews Forest. Mature conifer stands with dominants 100-130 years old occupy about 25 percent of the Andrews Forest, and about 30 percent has young stands resulting from logging during the past 40 years. A number of forest communities are associated with moisture and temperature gradients at different elevations.