Four treatments, all combinations of leaving or removing residual trees and shrubs or scarifying or not scarifying seedbeds, were evaluated for species differences in growth, vigor, and expression of dominance. Western larch was the dominant species in regeneration and growth but had begun to lose some of its advantage by age 25, particularly on scarified areas where overstocking commonly occurred. Douglas-fir was less sensitive to the treatments and, although significantly slower in absolute growth than larch, began to accelerate after 15 years of age. This study confirms that early cleaning and thinning will be necessary to achieve composition, density, and performance goals.
Cole, Dennis M.; Schmidt, Wyman C. 1986. Site treatments influence development of a young mixed-species western larch stand. Res. Pap. INT-RP-364. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 6 p.