Repeated Manual Release in a Young Plantation: Effect on Douglas-Fir Seedlings,Hardwoods, Shrubs, Forbs, and Grasses

摘要

Douglas-fir seedlings on the Arcata Resource Area, Bureau of Land Management,U.S. Department of the Interior, in central coastal California, were released by chain sawing and grubbing competing vegetation around them at different frequencies (0, 2, and 3 grubbings) over a 5-year period. After 5 years, average Douglas-fir stem diameter (measured at 12 inches above mean groundline) of seedlings grubbed at ages 1, 2, and 5 was 0.91 inches, and of seedlings grubbed after the first and fifth growing season was 0.95 inches. Both were significantly larger than counterparts in the control (0.57 inches).