Yellowstone forests are dominated by the lodgepole pine and are eventually replaced by other tree species after 80 to 100 years as a forest matures. In Yellowstone, a very short growing season due to high altitude and relatively poor soils allows the lodgepole pine to reach ages approaching three hundred years before other trees such as Engelmann spruce and subalpine fir become established. The lodgepole pines found throughout the Yellowstone Plateau high country grow in uninterrupted dense stands averaging similar ages in various groupings. Though trees normally found in more mature forests do occur, they are not found in large stands as in other forests in the Rocky Mountains. By the 1980s, much of the lodgepole pine forests in Yellowstone were between 200 and 250 years old and approaching the end of their life-cycle.