East of Cascade Range Crest, Oregon and Washington

Composition of Old Growth Ponderosa Pine Forests

The dominant species in ponderosa pine old-growth forests is, not surprisingly, ponderosa pine. In many forest patches it forms pure stands but is also found with other species. In dry sites it is with western juniper, along the eastern slopes of the Cascade Range it is found with Oregon white oak, in riparian corridors it is joined by quaking aspen, and in pumice-rich central Oregon, it associates with lodgepole pine. These days which the encroachment of shade tolerant species, however, it might very well have its greatest association with grand fir and Douglas fir.

Even without fire disturbance, ponderosa pine stands are often encroached by other species. Ingrowths of Douglas-fir and the true firs enter at moist sites especially as elevation increases and at ingrowths of juniper occur in dryer sites at the lower elevations.

Under this canopy, a sparse layer of grasses and shrubs grow. In Eastern Washington, a typical understory is snowberry, western serviceberry, and roses along with bluebunch wheatgrass. In the pumice regions of central Oregon, this understory changes to antelope bitterbrush, greenleaf manzanita, and Idaho fescue.

Few animal species live exclusively in the ponderosa pine zone. Mule deer, white-tailed deer, and elk enter to graze the shrubs, and predators – especially the reclusive mountain lion - follow them. Squirrels and chipmunks are common as well and are among the rodents that collect seeds from many of the shrubs and trees, thereby helping to distribute plant species, including ponderosa pine. In addition, a number of birds, such as blue grouse, find food and nesting sites in the shrubs of ponderosa pine forest.