Identify Major Rocky Mountain Trees Using Forest Zones

The pine-oak forest is replaced at about 8,000 feet on northfacing slopes by Douglas-fir. Aspen is also common in this zone and limber pine grows in places that are rockier and drier. This fir-aspen zone gets double the moisture of the pinyon-juniper belt, about 20 to 30 inches per year.
Sunlight seldom reaches the forest floor as aspen and fir grow thickly together so only trees and shrubs that tolerate shade grow here. These plants include kinnikinnick, honeysuckle, raspberry and mountain-ash.
Occasionally pure stands of lodgepole pine can be found and usually occur after fire kills Doug fir. This "pioneer" tree will seed in on the bare soil and is usually the first tree to revegetate burned-over areas.
More on aspen...
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