East of Cascade Range Crest, Oregon and Washington

Environment of the Old-Growth Ponderosa Pine Forests

Vegetation within the pondersosa pine forests must survive in a region of little precipitation that primarily falls in the winter as snow. As a result, these old-growth forests occupy drier sites than any other Pacific forest outside of the western juniper and oak woodlands. Precipitation ranges from 12 to 40 inches per year forming a mosaic of sites ranging from dry to moist. The growing season is comparatively short, the winters are cold, and even with summer temperature averages reaching 80-85°F, nighttime temperatures can drop below freezing.

The predominant characteristic of the ponderosa pine soils is that they are coarsely textured soils. In much of Oregon, these soils are made largely of pumice ejected from volcanoes such as the ancient Mount Mazama (now the site of Crater Lake) and Newberry.