Release of Below-Ground Carbon by Root-Soil Interactions

U.S. Forest Service scientist collaborates to improve climate change modeling

Projections of net carbon loss due to root-soil interactions, shown in blue, were strongest in temperate North America, Western Europe, Southeast Asia and Southern Africa. Image by Benjamin N. Sulman, Indiana University.
Projections of net carbon loss due to root-soil interactions, shown in blue, were strongest in temperate North America, Western Europe, Southeast Asia and Southern Africa. Image by Benjamin N. Sulman, Indiana University.

Chris Oishi, research ecologist at the Forest Service Coweeta Hydological Laboratory, recently worked with scientists from Indiana University and Princeton University to develop a new tool to model the sensitivity of soil organic carbon to changing environmental conditions, an area that has represented a critical uncertainty in climate change modeling. The research was published in the journal Nature Climate Change in early November.

“Soils contain more carbon than all of the atmosphere and the plant biomass on earth combined,” said Oishi. “This new modeling tool—named Carbon, Organisms, Rhizosphere and Protection in the Soil Environment (CORPSE)—represents a major advance in the ability of scientists to model the global carbon cycle, the essential component of all climate change modeling.”

As well as co-authoring the recent article, Oishi provided data and expertise for the set-up and interpretation of the site-level simulations conducted at Free-Air CO2 Enrichment( FACE) sites at Duke University and the Oak Ridge National Laboratory used to calibrate parts of the model.

“I’m interested in how the flows of mass and energy through different types of forests are influenced by environmental factors,” said Oishi. “Some of my previous research with collaborators from Duke University and the Forest Service Southern Research Station examined the long-term effects of elevated CO2 on carbon allocation and respiration from soil. This current paper focuses on some of the key processes involved in soil carbon dynamics and uses models to upscale stand-level experiments to a global scope. ”

Plants and trees are generally expected to grow faster under climate change, with key limitations. Calculating both the addition of carbon and its removal from the atmosphere as a result of this growth is a key component in climate change modeling, but the effect of interactions below ground have been difficult to capture.

The new tool CORPSE takes into account the chemicals and organisms in the soil that surround plant roots, identifying this highly active community as a major driver in atmospheric carbon dynamics.

Applying global simulations using CORPSE, the collaborators found that the activity of the soil microbes that derive their energy from plant root growth will partially offset carbon dioxide removal from the atmosphere as the result of greater plant growth expected under the higher levels of atmospheric carbon tied to climate change.

“Before this research, computer models were generally not able to simulate interactions between plant growth and carbon-releasing decomposition from soil microbes,” said Oishi. “The model has already been integrated into the generation of models used by the NOAA Geophysical Fluid Dynamics Laboratory, a major national climate modeling center.”

Read more in the news release from Indiana University.

Read the full text of the article.

For more information, email Christopher Oishi at  acoishi@fs.fed.us .

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