This extension note provides a summary of results obtained to date from studies initiated in 1992 to document and demonstrate the effects of different amounts and spatial arrangements of red alder on forest productivity, stand dynamics, and nitrogen availability in broadleaf-conifer mixedwood stands in coastal British Columbia. Replacement series experiments have been planted at two locations in B.C. to evaluate the effects of various proportions of red alder when grown in mixture with Douglas-fir. Mixedwood plantations have also been established at three locations following an additive design. In the additive design, Douglas-fir and western redcedar were planted at a density of 1100 sph (with the two species planted in equal proportions at alternating planting spots), and one of eight "broadleaf" density treatments was subsequently applied to randomly selected plots. These treatments included: 0, 50, 100, 200 and 400 red alder per hectare, 50 bigleaf maple per hectare, 200 Sitka alder per hectare, and a delayed planting of 100 red alder per hectare in year 5.
No significant treatment effects are evident at the end of five growing seasons from one replacement series and two additive design installations. Continued remeasurement of these installations and establishment of additional installations is planned.
Keywords: red alder, Douglas-fir, western redcedar, mixedwood management
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Updated April 17, 2007