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Modeling decay of woody residues helps managers understand forest growth

Date: September 05, 2018

Maintaining woody debris on forest sites is critical for maintaining carbon stores and modeling the rate of decay helps managers understand tree growth and and carbon sequestration.


Background

Wood stakes are inserted into the mineral soil to evaluate abiotic and biotic influences on wood decomposition.
Wood stakes are inserted into the mineral soil to evaluate abiotic and biotic influences on wood decomposition.
There is little data on woody debris (e.g., root, branch, and boles) decomposition rates to calibrate forest ecosystem models, mostly because this data is difficult to collect. However, this information is critical for modeling how forest stands respond to whole tree harvesting, stump removal, or loss of forest floor material. This information can be used to understand soil carbon sequestration, forest growth, nutrient cycling, and biological activity in a changing climate.

Sustainable forest management must take into account the interaction of harvest activities and ecological processes. This is often done with ecosystem-level ecological models, which are difficult to calibrate because of data collection challenges. One item that is particularly difficult to collect is the rate of wood decomposition. 

We are using standard wood substrates across a wide array of sites to determine surface, forest floor/mineral soil interface, and mineral soil decomposition rates. The standard substrate means that wood quality is held constant and, therefore, sites can be compared. In addition, wood is a normal component of forest soils and its decomposition is largely affected by changes in soil moisture and temperature. We used our wood decay data in the FORECAST model and determined that decomposition rates help show where nutrients that may leach from woody residues are important for sustained tree growth.This data is also useful for estimating the amount of carbon that may be sequestered in the soil after harvest activities.

Key Findings

  • Adding decomposition rates from standard wood stakes to the FORECAST model helped to predict where tree growth may be limited due to less nutrient cycling from decaying boles and branches.
  • As a precautionary principle, the forest floor (surface organic horizons) and root systems (stumps) should remain intact after harvest operations.  

Featured Publications

Risch, Anita C. ; Jurgensen, Martin F. ; Page-Dumroese, Deborah S. ; Schutz, Martin , 2013
Jurgensen, Martin ; Reed, David ; Page-Dumroese, Deborah S. ; Laks, Peter ; Collins, Anne ; Mroz, Glenn ; Degorski, Marek , 2006


Forest Service Partners: 
Jim Archuleta, USFS Region 6, Jeff Bruggink, USFS Region 4, Derek Milner, Flathead National Forest.
External Partners: 
Juan Blanco, University of Navarro, Spain;
Mike Curran, British Columbia Ministry of Forests (retired);
Martin Jurgensen, Michigan Technological University;
Joanna Walitalo, PhD student, Michigan Technological University.
Research Location: 
Findings are from British Columbia, Switzerland, Poland, Finland, and western USA.