Photo Credit

Courtesy photo by Oak Ridge National Laboratory.

An aerial view looking downward into a chamber where scientists are conducting experiments on plant response to increased CO₂.

On a 20-acre bog in the Marcell Experimental Forest in northern Minnesota, 10 open-topped enclosures rise more than 23 feet out of the peatland, connected by walkways that seem to float over a layer of Sphagnum moss. With funding from the  Department of Energy (DOE), and in partnership with DOE’s Oak Ridge National Laboratory (ORNL) and expert scientists from around the world, Northern Research Station scientists are testing the effects of climate change on carbon sequestration and storage in peat bogs. These bogs, formed over thousands of years as dead and decaying plant material and coprogenous earth accumulate, are natural sinks for carbon. While accounting for just 3 percent of the planet’s landmass, peatlands hold a third of global soil carbon because the cool, wet, and acidic conditions slow decomposition. 

Yet, despite storing massive amounts of carbon, peatlands have not been represented in the global Earth Systems Models that scientists use to simulate carbon cycling processes and investigate future climate scenarios. The Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment is changing that. Research from the study informs the DOE’s Energy Exascale Earth System land model (ELM), which is part of the ensemble of models used by the Intergovernmental Panel on Climate Change. 

For more in-depth information on SPRUCE, please visit: https://mnspruce.ornl.gov/

Approach

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 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 enclosures 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?

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.