US Forest Service Research & Development
Contact Information
  • US Forest Service Research & Development
  • 1400 Independence Ave., SW
  • Washington, D.C. 20250-0003
  • 800-832-1355
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Tim Harrington

Timothy B. Harrington, Ph.D.

Research Forester and Team Leader
3625 93rd Ave. SW
United States

Phone: 360-753-7747
Contact Timothy B. Harrington, Ph.D.

Current Research

My current work is exploring several research emphases: overstory and understory relationships in managed Douglas-fir forests; longer-term effects of vegetation control and logging debris manipulation on Douglas-fir plantation productivity; regeneration biology of Scotch broom; herbicide treatments for controlling invasive, nonnative plant species; and effects of logging debris and associated light quality on understory plants.

Research Interests

Biology and management of invasive, nonnative plant species; conifer seedling growth and physiology responses to microenvironment; restoration of understory plant communities in managed conifer forests; comparative growth and yield of Douglas-fir stands; and long-term effects of forest vegetation management and thinning on stand structure.

Past Research

My past work has explored the physiology of Douglas-fir under different levels of competition from woody and herbaceous vegetation; bud production and shoot growth of Douglas-fir; shoot growth of southern pines; and restoration of longleaf pine communities in the southern United States.

Why This Research is Important

Invasive, nonnative plants threaten the biodiversity and many ecological functions of Pacific Northwest forests. Methods are needed to prevent or mitigate plant invasions to protect native plant and animal communities. Research on conifer regeneration is critical to appropriate management of public and private forest land to ensure steady production of the ecological services that society demands.


  • Oregon State University, Ph.D. Silviculture 1989
  • Oregon State University, M.S. Forest Ecology 1982
  • Louisiana State University, B.S. Botany 1980

Featured Publications & Products


Research Highlights


More Scotch broom found where logging debris was removed

Scotch broom, a nonnative, invasive species, is a severe competitor of young Douglas-fir.


New Herbicides Developed to Fight Scotch Broom

Scotch broom is a large, nonnative shrub that has invaded forest sites throughout the Pacific Northwest. Three recently developed herbicides pro ...


Presence of tanoak reduces Douglas-fir mortality from black-stain root disease

Black-stain root disease is a native pathogen of conifers in the Pacific Northwest. The disease reduces growth and ultimately kills the infected ...


Some Logging Debris Cover Boosts Growth of Douglas-fir Seedlings on Low-nutrient Site

Stem growth of Douglas-fir seedlings with 40 percent debris cover and competing vegetation was greater than that of seedlings with zero or 80 pe ...


Last updated on : 09/10/2021