Forty felled dominant and codominant Pacific silver fir trees (Abies amabilis Dougl. ex Forbes) from 39 locations provided the basis for height-age and site index curves. Trees were from upper slope forests of the Cascade Range in Oregon and Washington. Trees ranged in age from 100 to 300 years and were identified by their height-growth trend as free growing throughout their lives. Twenty additional dominant trees with height growth retarded when they were young were excluded from the site index and height-growth analyses. The early rate of diameter growth of these 20 trees was used to develop a general guideline identifying non free-growing dominant trees. Equations and height-age curves are presented. A multiple regression equation was developed to express site index (height at age 100) as a function of total tree height and age at breast height. Equations were developed .to estimate the number of years free-growing trees need to reach breast height for the range of site index values. Conversion equations are provided to estimate height at age 50 for curves representing index heights at age 100. The results give forest managers working tools for use in managing silver fir.
Hoyer, Gerald E.; Herman, Francis R. 1989. Height-age and site index curves for Pacific silver fir in the Pacific Northwest. Res. Pap. PNW-RP-418. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 33 p