In Redwood forests common associates are Douglas-fir, grand fir, and tanoak. This type extends inland and to the reaches of coastal fogs. Ponderosa Pine is associated with white fir. It is usually distributed to the west, north, and east of the Great Basin and the deserts of the Southwest. 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. Snowberry, chokeberry, and western serviceberry are common understory shrubs. Chaparral consists of heavily branched dwarfed trees or shrubs, commonly evergreens, whose canopy at maturity covers at least 50 percent of the ground. The ponderosa pine forest is found in the deserts of the southwest.