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Root disease quietly holds back forest carbon storage

Date: September 13, 2016

Dramatic disturbances such as wildfires and harvests command attention, but subtler processes such as root disease can be equally important in determining how much greenhouse gas a forest takes out of the atmosphere


Armillaria mellea is a parasitic fungus that frequently causes root disease in forests of the US.  Image uploaded to Wikimedia Commons by Mars 2002 under a Creative Commons License
Armillaria mellea is a parasitic fungus that frequently causes root disease in forests of the US. Image uploaded to Wikimedia Commons by Mars 2002 under a Creative Commons License

Growing forests take greenhouse gases such as carbon dioxide out of the atmosphere. National forests must account for how natural and management-oriented disturbance processes affect carbon storage as an ecosystem benefit.  Although it doesn’t always cause large, eye-catching areas of mortality, root disease likely affects carbon storage by reducing tree growth and regeneration over vast areas.  However, no previously available tools allowed monitoring of the effect of root disease on carbon storage at a landscape level.

We compared the effects of root disease against the effects other types of forest disturbance across six national forests in Idaho and Montana from 1990-2011. To compare the effects we used a monitoring tool called the Forest Carbon Management Framework (ForCaMF), which makes use of Forest Service Forest Inventory and Analysis data, an empirical growth model, and time series of Landsat satellite imagery. Despite several large fires that burned across these landscapes during the study period, retrospective ForCaMF analysis showed that fire and root disease had approximately equal impacts on carbon storage. While tools informing management of forest carbon storage have generally ignored long-term disturbance processes such as root disease, the recent history of several national forests suggests that such disturbances can be just as important to the carbon cycle as the more conspicuous events like wildfires.

Key Findings

  • While root disease typically has a lower per-acre impact on carbon storage than processes like intense wildfires, disease can affect much larger areas, and those impacts can last for decades.

  • Root disease and fires had approximately equal effects on carbon storage across six national forests from 1990 to 2011.

Featured Publications

Healey, Sean P. ; Raymond, Crystal L. ; Lockman, I. Blakey ; Hernandez, Alexander J. ; Garrard, Chris ; Huang, Chengquan , 2016
Healey, Sean P. ; Urbanski, Shawn P. ; Patterson, Paul L. ; Garrard, Chris , 2014


Principal Investigators: 
Principal Investigators - External: 
Crystal Raymond - Seattle City Light
Chris Garrard - Utah State University
Alex Hernandez - Utah State University
Forest Service Partners: 
Blakey Lockman (Forest Health Protection)