ABSTRACT
Ponderosa pine occurs on a great variety of landforms, soil types, and climatic regimes both in pure and mixed stands which dominate a vast array of understory plants. Several investigators in the western United States and southwestern Canada have reported cattle abortions resulting from ingestion of pine needles. The North Plateau race of ponderosa pine occurs in a climax formation in the lower elevations of forest development on the east slopes of the Cascade Mountains. H. A. Fowells summarized the vast array of soils, landforms, and climates which determine the habitats occupied by ponderosa pine. Ponderosa pine most frequently regenerates following disturbance by fire, logging, insect or disease outbreaks, or heavy grazing. Timber harvest and prescribed burning can increase forage for cattle and wildlife in both seral and climax ponderosa pine communities, depending on understory plant composition, range condition, fire effects, and site.
