It is usually distributed to the west, north, and east of the Great Basin and the deserts of the Southwest. Such admixtures produces the mixed conifer type. The Lodgepole pine is best developed on moist, sandy or gravelly loam. Common associates are subalpine fir, western white pine, Engelmann spruce, aspen, and larch. The fir-spruce forests are the true firs, Engelmann spruce, or Colorado blue spruce.
Common associates are lodgepole pine, and at high elevations mountain hemlock.
Aspen is usually the first to dominate burns and other disturbed areas, where it produces even-aged stands. It has a herbaceous understory, commonly forbs, but sometimes grasses, and sedges. The ponderosa pine forest is found in the deserts of the southwest. 2, PAGE 817. 19 American Ornithology Union.