[ Back to EurekAlert! ] Public release date: 8-May-2009
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Contact: Sherri Richardson Dodge
srichardsondodge@fs.fed.us
503-808-2137
USDA Forest Service, Pacific Northwest Research Station

Managing Douglas-fir forests for diversity

May provide multiple uses including wildlife, timber production

PORTLAND, Ore. May 8, 2009. Creating diverse forests for multiple uses is important to natural resource managers and landowners. A study conducted in southwestern Oregon provides forest managers with information that offers choices when managing land for a variety objectives that may include a high level of wood production, a moderate level of wood production with some wildlife habitat features, or low wood production that provides cover and forage for a wider variety of wildlife species.

"Land managers need effective approaches for creating and modifying forest stand structures to satisfy a broad range of objectives," explains Tim Harrington, a research forester at the Forest Service's Pacific Northwest Research Station. "Silvicultural treatments can be used to shift competitive interactions between conifers and hardwoods to create the desired balance between wood production and wildlife habitat."

Harrington and John Tappeiner, an emeritus Oregon State University forestry professor, initiated a study in 1983 in southwestern Oregon on Douglas-fir plantations near Cave Junction and Glendale, Oregon. During the first phase of the study, when the plantations were 1 or 2 years old, a single herbicide treatment was used to reduce hardwood density to several levels. The Douglas-fir were thinned at age 15 to leave densities of 120 to 220 dominant trees per acre.

About 8 years later (ages 23 to 25), the scientists found that:

"Managing stands with moderate hardwood densities enables a stratified structure to develop with conifers and hardwoods occupying dominant and intermediate canopy layers, respectively," explains Harrington. "Combining high hardwood densities with precommercial thinning of Douglas-fir creates a codominant stand structure with conifers and hardwoods occupying the same canopy layer. Managers may also want to retain some hardwoods in areas prone to black stain root disease, since the hardwoods may reduce mortality of planted Douglas-fir following thinning."

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Read the entire report, Long-term effects of tanoak competition on Douglas-fir stand development, in the April issue of Canadian Journal of Forestry.

Source: Tim Harrington, research forester, (360) 753-7674, tharrington@fs.fed.us

The Pacific Northwest Research Station is one of seven research facilities in the USDA Forest Service. The station's headquarters is in Portland, Ore., with 11 locations in Alaska, Oregon, and Washington. The station has about 500 employees.



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