Ponderosa pine forest is a plant association and plant community dominated by ponderosa pine and found in western North America. It is found from the Rocky Mountains to the Pacific Coast Ranges in the Western United States and Western Canada. In the south and east, ponderosa pine forest is the climax forest, while in the more northern part of its range, it can transition to Douglas-fir or grand fir, or white fir forests. Understory species depends on location. Fire suppression has led to insect outbreaks in ponderosa pine forests.