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Individual Highlight

Maintaining Long-term Productivity of Inland Northwest Forests After Bioenergy Harvesting

Photo of Researchers collect the forest floor to determine amount of carbon. U.S. Department of Agriculture Forest Service.Researchers collect the forest floor to determine amount of carbon. U.S. Department of Agriculture Forest Service.Snapshot : As the U.S. moves towards a more green economy, it is critical to understand the long-term impacts of harvest operations on both above and below ground productivity. Research at the Coram Experimental Forest points to resilient western larch forests in the cool-moist climatic regime that can fully recover carbon and nutrients before the next harvest rotation. Forty years after cable harvesting and broadcast burning, scientists found few long-term impacts on soil, understory, and overstory in larch forests.

Principal Investigators(s) :
Page-Dumroese, Deborah S.  
Research Location : Iinland Northwest - Washington, Idaho, Montana
Research Station : Rocky Mountain Research Station (RMRS)
Year : 2016
Highlight ID : 974

Summary

As the United States moves towards a more green economy, it is critical to understand the long-term impacts of harvest operations on both above and below ground productivity. Harvesting for bioenergy often extracts more organic matter from forest ecosystems than conventional harvesting does. Since organic matter plays a key role in forest productivity, concerns over the potential long-term negative impacts of biomass harvesting on forest and soil productivity (i.e., changing nutrient or water cycling, soil physical properties, and loss of the forest floor) have emerged. Numerous studies from around the world have shown that there can be positive, negative, or neutral impacts from harvest operations, but there are few studies conducted in the Inland Northwest that provide empirical knowledge and comprehensive understanding. Research at the Coram Experimental Forest points to resilient western larch forests in the cool-moist climatic regime that can fully recover carbon and nutrients before the next harvest rotation. Forest Service scientists used a site on the Coram Experimental Forest that had been harvested by cable logging and broadcast burned in 1974 to evaluate long-term impacts and recovery. There were no statistical differences in soil chemical properties, shrub biomass diversity, or carbon and nitrogen pool distribution between harvested and undisturbed plots. They concluded that site productivity in this western larch forest was unaffected by harvesting. Resampling a western larch forest 38 years after bioenergy harvesting and broadcast burning showed that site productivity in this cool-moist forest was unaffected by biomass removal.Shrub diversity and biomass were the same or greater than pre-harvest samples and indicate the shrub community is quite resilient to biomass harvesting. Intensive biomass utilization, with or without broadcast burning, has few long-term impacts on soil carbon, organic matter, and nutrients.

Forest Service Partners

External Partners

  • Joanne Tirocke (Technician), Rocky Mountain Research Station
  • Christopher Keyes, University of Montana (Co-Principal Investigator)
  • Woongsoon Jang, University of Montana (Co-Principal Investigator)