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Maintaining long-term productivity of Inland Northwest forests after bioenergy harvesting

Date: August 25, 2016

Forty years after cable harvesting and broadcast burning, scientists found few long-term impacts on soil, understory, and overstory in larch forests

Researchers collect the forest floor for carbon determination.
Researchers collect the forest floor for carbon determination.
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.

Key Findings

A core sample for measuring carbon in the mineral soil.
A core sample for measuring carbon in the mineral soil.
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.

Featured Publications

Jang, Woongsoon ; Page-Dumroese, Deborah S. ; Keyes, Christopher R. , 2016
Scott, D. Andrew ; Page-Dumroese, Deborah S. , 2016
Jang, Woongsoon ; Keyes, Christopher R. ; Page-Dumroese, Deborah , 2015

Principal Investigators: 
Forest Service Partners: 
Joanne Tirocke (Technician)
External Partners: 
Christopher Keyes, University of Montana (Co-Principal Investigator)
Woongsoon Jang, University of Montana (Co-Principal Investigator)