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Abstract
A series of 18 precommercial thinning trials was established in true fir-hemlock stands in the Olympic Mountains and along the west side of the Cascade Range in Washington and Oregon from 1987 through 1994. This paper documents establishment of these installations and presents some preliminary observations and results. Substantial differences in growth rates in height and diameter were observed among Pacific silver fir, western hemlock, and noble fir. Diameter growth of all species increased as spacing increased, but height growth of silver fir and noble fir decreased at wider spacings in some areas. These installations will provide a unique source of information on early development of managed stands of these species, for which little information now is available.
Citation
Curtis, Robert O.; Clendenen, Gary W.; Henderson, Jan A. 2000. True fir-hemlock spacing trials: design and first results. Gen. Tech. Rep. PNW-GTR-492. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 35 p