Pacific Northwest Research Station

Title: Comparative effects of precommercial thinning, urea fertilizer, and red alder in a site II, coast Douglas-fir plantation.

Author: Miller, Richard E.; Obermeyer, Edmund L.; Anderson, Harry W.

Date: 1999

Source: Res. Pap. PNW-RP-513. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 25 p

Station ID: RP-PNW-513

Description: We varied the number of red alder retained with 300 Douglas-fir per acre on a high-quality site in coastal Oregon. Alder densities of 0, 20, 40, and 80 per acre were tested. Our fifth treatment eliminated nitrogen-fixing alder, but substituted nitrogen fertilizer. Treatment 6 had neither thinning nor alder control. Treatments were randomly assigned within each of three blocks in a 9-year-old plantation. In pure Douglas-fir plots, gross volume growth was similar for nonfertilized plots, indicating no measurable benefits of additional nitrogen. In mixed stands, red alder reduced yield of associated Douglas-fir but not yield of combined species. Similar comparisons are needed at other locations, especially those with known nitrogen deficiency.

Keywords: Mixed stands, competition (plant), Douglas-fir, Pseudotsuga menziesii, red alder, Alnus rubra, thinning, nitrogen fertilization, volume growth

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Citation

Miller, Richard E.; Obermeyer, Edmund L.; Anderson, Harry W.  1999.  Comparative effects of precommercial thinning, urea fertilizer, and red alder in a site II, coast Douglas-fir plantation..   Res. Pap. PNW-RP-513. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 25 p.