 The previous major Yellowstone fire was in the early to mid-18th century, well before the arrival of white explorers.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.