Forest Disturbance Processes


Recommended Resources

Kolka, R.; Dietzman, D. 2014. The SPRUCE Experiment Testing Peatland Response to a Changing Climate. USDA Forest Service Briefing Paper.

Kolka, R. 2013. Disturbance effects on peatlands.  Invited presentation to Symposium on Wetland Values. Society of Wetland Science Annual Meeting, Duluth, MN.

Kolka, R. and P. Hanson. 2012. The SPRUCE experiment.  Television Interview. KDLH Duluth News, Channel 6, aired 10/12/12.

Kolka, R.; Hanson, P.; Iversen, C.; Sebestyen, S.; Norby, R.; Palik, B.; Thornton, P.; Warren, J.; Wullschleger, S.; Griffiths, N; Hook, L. 2012. Spruce-Peatland Responses Under Climatic and Environmental change: an in situ warming by CO2 manipulation of a northern Minnesota bog. Proceedings of the St. Louis River Estuary Science Summit. March 8-9, University of Wisconsin Superior. p. 39.

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The Spruce-Peatland Response Under Climate and Environmental Change (SPRUCE) Experiment

[photo:] Aerial view of SPRUCE site.  Photo provided by Oak Ridge National Lab.Research Issue

Wetlands, especially organic rich peatlands, have historically been massive sinks for carbon but climate change may be changing the source/sink relationship.  If northern peatlands become carbon sources (or even lesser sinks) the possible feedbacks to the atmosphere could have global implications on carbon dioxide levels in the atmosphere.

Our Research

Through collaboration with the U.S. Department of Energy and Oak Ridge National Lab, a large experiment is installed to test the effects of increased soil and air temperature and elevated carbon dioxide levels on northern peatland ecosystems.  The experiment provides a platform for testing mechanisms controlling vulnerability of wetland ecosystems to important climate change variables. The Forest Service’s Marcell Experimental Forest in Northern Minnesota is hosting the Spruce and Peatland Under Climatic and Environmental Change (SPRUCE) experiment because of its rich history of research on peatlands and long-term hydrological, climatological and chemistry data bases.  The $50 million experiment is funded by the Department of Energy and is projected to run for 10 years. The SPRUCE infrastructure consists of 10 large (40 ft dia., 30 ft tall) open-topped, controlled-environment enclosures. The atmosphere and soil (peat) in the enclosures are maintained at 5 different temperatures (no change, +4, +8, +12, and +16° F) relative to temperatures measured outside the enclosures and carbon dioxide will be approximately doubled in one-half of the chambers throughout the 10 year period of the experiment. Heating of the soil began in June 2014, atmospheric heating began in July, 2015 and carbon dioxide additions are planned to begin in June 2016.

Key science questions being investigated include the following:

  • How vulnerable are peatland ecosystems and their component organisms to atmospheric and climate change?
  • To what degree will changes in plant physiology under elevated CO2 impact a species’ sensitivity to climate or competitive capacity within the community?
  • Will full belowground warming release unexpected amounts of greenhouse gases and solutes from high-C-content northern forests?
  • What are the critical air and soil temperature response functions for ecosystem processes and their constituent organisms?
  • Will ecosystem services (e.g. biogeochemical, hydrological, or societal) be compromised or enhanced by atmospheric and climate change?

Expected Outcomes

The experiment promises to provide important data on ecosystem response to climate and atmospheric change that will feed into both ecosystem and global climate models that will better allow us to predict future climate. Better predictions will assist policy makers and the public to make more informed decisions related to mitigation and adaptation to climate change.

Research Results

We conducted numerous studies to assess peatland vegetation, soil, microbial communities, chemistry, hydrology, gas fluxes and a number of other parameters to characterize the peatland community prior to manipulation.  See links to publications and presentations that have resulted from pre-manipulation studies.  Results from studies that have assessed parameters affected by soil and atmospheric warming are just beginning to come out.
For a list of related publications: http://mnspruce.ornl.gov/content/project-publications
For a list of SPRUCE related presentations see: http://mnspruce.ornl.gov/content/presentations-and-posters

Research Participants

  • Randy Kolka, Research Soil Scientist, USFS Northern Research Station
  • Stephen Sebestyen, Research Hydrologist, USFS Northern Research Station
  • Brian Palik, Research Ecologist, USFS Northern Research Station

Research Partners

Last Modified:

December 6, 2015