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Recommended Resources

Oak Ridge National Laboratory SPRUCE website

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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Spruce and Peatland Responses Under Changing Environments

[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 Responses Under Changing Environments (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 degrees Fahrenheit) 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 began in June 2016.

Key science questions being investigated include the following:

  • How vulnerable are peatland ecosystems and their component organisms to atmospheric change and changing environments?
  • 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-carbon-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 changing environments?

Expected Outcomes

The experiment promises to provide important data on ecosystem response to changing environments that will feed into both ecosystem and global climate models and 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 changing environments.

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.

Selected Recent Publications

Fernandez, Christopher W.; Heckman, Katherine; Kolka, Randall; Kennedy, Peter G. 2019. Melanin mitigates the accelerated decay of mycorrhizal necromass with peatland warming. Ecology Letters. 22(3): 498-505. https://doi.org/10.1111/ele.13209.

McPartland, Mara Y.; Kane, Evan S.; Falkowski, Michael J.; Kolka, Randy; Turetsky, Merritt R.; Palik, Brian; Montgomery, Rebecca A. 2019. The response of boreal peatland community composition and NDVI to hydrologic change, warming and elevated carbon dioxide. Global Change Biology 25: 93-107. https://doi.org/10.1111/gcb.14465​.

Iversen, Colleen M.; Childs, Joanne; Norby, Richard J.; Ontl, Todd A.; Kolka, Randall K.; Brice, Deanne J.; McFarlane, Karis J.; Hanson, Paul J. 2017. Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat. Plant and Soil. 20 p. http://dx.doi.org/10.1007/s11104-017-3231-z.

Haynes, Kristine M.; Kane, Evan S.; Potvin, Lynette; Lilleskov, Erik A.; Kolka, Randall K.; Mitchell, Carl P.J. 2017. Gaseous mercury fluxes in peatlands and the potential influence of climate change. Atmospheric Environment. 154: 247-259. https://doi.org/10.1016/j.atmosenv.2017.01.049.

Wilson, R.M.; Hopple, A.M.; Tfaily, M.M.; Sebestyen, S.D.; Schadt, C.W.; Pfeifer-Meister, L.; Medvedeff, C.; McFarlane, K.J.; Kostka, J.E.; Kolton, M.; Kolka, R.K.; Kluber, L.A.; Keller, J.K.; Guilderson, T. P.; Griffiths, N. A.; Chanton, J. P.; Bridgham, S. D.; Hanson, P. J. 2016. Stability of peatland carbon to rising temperatures. Nature Communications. 7: 13723. 10p. Includes supplemental pages. https://doi.org/10.1038/ncomms13723.

Hanson, P.J.; Gill, A.L.; Xu, X.; Phillips, J.R.; Weston, D.J.; Kolka, R.K.; Riggs, J.S.; Hook, L.A. 2016. Intermediate-scale community-level flux of CO2 and CH4 in a Minnesota peatland: putting the SPRUCE project in a global context. Biogeochemistry. 129(3): 255-272. https://doi.org/10.1007/s10533-016-0230-8.

Griffiths, Natalie A.; Hanson, Paul J.; Ricciuto, Daniel M.; Iversen, Colleen M.; Jensen, Anna M.; Malhotra, Avni; McFarlane, Karis J.; Norby, Richard J.; Sargsyan, Khachik; Sebestyen, Stephen D.; Shi, Xiaoying; Walker, Anthony P.; Ward, Eric J.; Warren, Jeffrey M.; Weston, David J. 2017. Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment. Soil Science Society of America Journal. 81: 1668-1688. https://doi.org/10.2136/sssaj2016.12.0422.

Ma, Shuang; Jiang, Jiang; Huang, Yuanyuan; Shi, Zheng; Wilson, Rachel M.; Ricciuto, Daniel; Sebestyen, Stephen D.; Hanson, Paul J.; Luo, Yiqi. 2017. Data-Constrained Projections of Methane Fluxes in a Northern Minnesota Peatland in Response to Elevated CO2 and Warming. Journal of Geophysical Research: Biogeosciences. 122(11): 2841-2861. https://doi.org/10.1002/2017JG003932.

Walker, Anthony P.; Carter, Kelsey R.; Gu, Lianhong; Hanson, Paul J.; Malhotra, Avni; Norby, Richard J.; Sebestyen, Stephen D.; Wullschleger, Stan D.; Weston, David J. 2017. Biophysical drivers of seasonal variability in Sphagnum gross primary production in a northern temperate bog. Journal of Geophysical Research: Biogeosciences. 122: 1078-1097. https://doi.org/10.1002/2016JG003711.

Griffiths, N.A.; Sebestyen, S.D. 2016. Temporal dynamics in the vertical profiles of peat porewater chemistry in a northern peatland. Wetlands, 36: 1119-1130.

Shi, X.; Thornton, P.E.; Ricciuto, D.M.; Hanson, P J.; Mao, J.; Sebestyen, S.D.; Griffiths, N.A.; Bisht, G. 2015. Representing northern peatland microtopography and hydrology within the Community Land Model. Biogeosciences. 12(21): 6463-6477. https://doi.org/10.5194/bg-12-6463-2015.

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: February 11, 2019