Initial Shock and Long-Term Stand Development Following Thinning in a Douglas-fir Plantation

Abstract

Abstract Responses following the application of six precommercial thinning treatments to a 27-year-old Douglas-fir plantation (2.4-m spacing, height at age 100 = 24 m) have been monitored for 25 years. Spacing after thinning ranged from 3.4 m to 8.1 m. Immediately following thinning, trees exhibited thinning shock; that is, substantial height growth reductions. The severity and duration of the shock effect were partially related to the severity of thinning. From 15 to 25 years following thinning, however, height growth was positively related to growing space with the best height growth at the wider spacings. Diameter growth increased following thinning, with the range in diameter growth rates between spacings increasing over time. Basal area and volume growth per hectare were reduced by treatment, but the differences among spacings are decreasing. Forest Sci. 29:33-46.