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Individual Highlight

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

Photo of A researcher collects a soil sample that will be analyzed to determine how retention of logging debris affects nutrient levels. Tim Harrington, USDA Forest ServiceA researcher collects a soil sample that will be analyzed to determine how retention of logging debris affects nutrient levels. Tim Harrington, USDA Forest ServiceSnapshot : Stem growth of Douglas-fir seedlings with 40 percent debris cover and competing vegetation was greater than that of seedlings with zero or 80 percent debris cover because the intermediate cover of debris both reduced herb abundance and increased availability of soil water and nitrogen.

Principal Investigators(s) :
Harrington, Timothy B., Ph.D. 
Research Location : Washington; Oregon
Research Station : Pacific Northwest Research Station (PNW)
Year : 2013
Highlight ID : 520

Summary

Scientists conducted a four-year study on two recently harvested forest sites in western Washington and Oregon to determine how logging debris and competing vegetation interacted to affect growth of planted Douglas fir seedlings. They found stem growth of seedlings with 40 percent debris cover and competing vegetation was greater than that of seedlings with zero or 80 percent debris covers because the intermediate cover of debris both reduced herb abundance and increased availability of soil water and nitrogen. Where competing vegetation was removed, seedling growth was greatest with 80 percent debris cover because it reduced soil temperature and evaporation, resulting in greater availability of soil water and nutrients. Forest managers of Green Diamond Resource Company and Port Blakely Tree Farms, LLC, are using the information to justify retention of moderate levels of logging debris in combination with herbicide treatments to provide short-term control of competing vegetation and increased growth of planted conifers. Washington State's Department of Natural Resources is using this information regarding the benefits of retaining logging debris on low nutrient sites to aid forest regeneration to inform planning for biomass energy harvesting, animal damage control, and wildfire hazard reduction.

Forest Service Partners

External Partners

 
  • Green Diamond Resource Company
  • Port Blakely Tree Farms, LLC
  • University of Minnesota
  • Virginia Tech
  • Weyerhaeuser Company

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