East of Cascade Range Crest, Oregon and Washington

Old Growth Ponderosa Pine Forests

The forests of the Pacific Northwest are known for large, long-lived woody species and the ponderosa pine forests are no exception. Pondersosa pine trees can reach diameters over 100 inches at breast height and live 400 years or more. On drier sites they may share space with two shrub species that may also live a long time – antelope bitterbrush and big sagebrush can both live more than of 100 years. Ponderosa pine forests are also associated with many other woody plants such as manzanita, snowberry, ceanothus, spirea, and oak trees on sites ranging from dry to moist and elevations low to high.

Moisture and fire dictate much of the character of these forests. Prior to 1900, ponderosa pine forests were typically open and grassy on the drier sites with regular, low intensity fires. On moister sites they were dense, with shrubs and infrequent, but severe fires. Over the last 100 years the ponderosa pine forests have been modified by fire suppression, which has reduced the amount of open, grassy stands.

The ponderosa pine zone is found primarily east of the Cascade crest from central Washington down to the Upper Klamath region of Oregon. It is also found in the Blue, Ochoco, and Wallowa Mountains of northeastern Oregon and southeastern Washington, and the Okanogan Highlands of northeastern Washington. There are even some patches of ponderosa pine in western Oregon along the Willamette valley and in southwestern Oregon.

Ponderosa pine forests occur at low-to-mid elevations that range from 2,000-4,000 feet in Washington to 3,000-6,500 feet in central Oregon. Above this zone these mature forests give way to Douglas-fir and true fir zones of the moister, colder high elevations. Along its lower reaches, the land becomes too dry to support ponderosa pine and so these trees give way to western juniper, sagebrush, or grasslands zones.

Scenic of ponderosa forest, Wallowa-Whitman National Forest.