While the previous system accounted for carbon dioxide emissions from plants and human sources, it did not account for the increased carbon content in soil and the resulting emissions, according to an IU news release.
Benjamin Sulman, a postdoctoral researcher working under associate professor Richard Phillips at IU, authored the study published online Monday in Nature Climate Change.
The study was titled “Microbe-driven turnover offsets minral-mediated storage of soil carbon under elevated CO2.”
The study was able to successfully identify the community of chemicals and organisms in the area of soil surrounding plants’ roots known as the ?rhizosphere.
All together, the Earth’s soil holds more carbon than both its biospphere and atmosphere combined.
The biosphere refers to all of the ecosystems on Earth and all of the living things that make them up.
Climate change has led to a number of changes in the environment, many linked to carbon dioxide emissions and the carbon cycle, the moving of carbon through the global ecosystem.
The increased emission of carbon dioxide has led to an increase in plant life, which depends on carbon dioxide uptake to produce food.
The increased activity in the rhizosphere, including more breakdown of sugars and organic compounds from the living roots, leads to an increase in fungi and bacteria, thus accelerating the decomposition of carbon in the soil and increasing carbon dioxide emissions, Sulman said in the release.
Sulman also said this increased activity in the rhizosphere can change carbon into forms that are more easily trapped in soil, allowing them to remain in the soil for longer periods of time.
The research team conducted global surveys, which found that the increased root activity has depleted the carbon stock in soils, counteracting what was seen as an increase due to increased plant growth, according to IU.
Simultaneously, the removal of carbon dioxide from the atmosphere that was observed as a result of increased plant growth may be partially offset by the increase in soil activity, particularly the rapid decomposition .
This effect was primarily found in temperate North America, Western Europe, Southeast Asia and Southern Africa.
Boreal North America, Siberia and tropical South America saw the largest gains in carbon content in the soil.
All of these factors are dependent upon the type of vegetation present, the climate and the makeup of the soil.
Simulations were projected for 30 years, according to the University.
In cold temperatures, particularly high altitude areas, decomposition is limited. In these areas, it was found that activity in the rhizosphere stimulated the trapping of carbon in soil.
In regions such as tropical South America, the high clay content in the soil locked carbon particles onto minerals, thus keeping them from decomposing.
However, in these same areas, rapid decomposition caused by warm temperatures and high levels of moisture slowed the accumulation of decomposable organic matter.
Before this research, the modeling tool was unable to account for the microbial activity resulting from increased plant growth.
The new modeling system, called Carbon, Organisms, Rhizosphere and Protection in the Soil Environment, or CORPSE, will allow researchers to more accurately predict the global carbon cycle.
“This model will allow critical plant-soil interaction processes to be included in future climate assessments,” Phillips said in the release. “To not consider how microbes influence soil carbon in offsetting ways, promoting losses through enhanced decomposition but gains by protecting soil carbon, would lead to overestimates or underestimates of the role soils play in influencing global climate.”
The model is already being used in the next generation of the global land model, which the National Oceanographic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory uses for climate simulations.
The research was funded by the U.S. Department of Commerce, the U.S. Department of Agriculture’s SFRI Program, BP and Princeton University, according to the release.
The Gaea supercomputer of the National Climate-Computing Research Center at Oak Ridge National Laboratory was used for the global simulations with the support of NOAA’s Geophysical Fluid Dynamics Laboratory.
Team members apart from Phillips and Sulman included Christopher Oishi of the U.S. Forest Service and Elena Shevliakova and Stephen W. Pacala of Princeton University.
“These experiments will enable us to further test and refine the underlying processes in the CORPSE model and should lead to improved predictions of the role of plant-soil interactions in global climate change,” Sulman said.
