Complicating matters, 99.9 percent of the microbes in the soil cannot be grown in the lab, so scientists must study them where they live. The molecular and genomic techniques to do so are a specialty of the Konstantinidis lab.
The researchers traveled to the Kessler Farm Field Laboratory in McClain County, Oklahoma, where they conducted their study on grassland soils, which had been abandoned for agriculture use for more than 20 years. The scientists warmed plots of soil with radiators set a few feet above the ground for 10 consecutive years. They warmed these plots 2 degrees Celsius, which many climate models forecast as the global temperature increase over the next 50 years.
The researchers took samples of the plants, measured the carbon content and the number of microbes in the soil, and documented any changes in the warm plots versus the control plots. The team also extracted DNA from the soil and identified the genetic composition and changes of the microbes living there.
The plants in the warm plots grew better and higher. As the plants started senescing at the end of the season, their higher biomass led to more carbon in the soil. However, the microbial communities had increased their rate of respiration, which converted soil organic carbon to carbon dioxide (CO2), so the total carbon in the warm and control soils was similar.
The microbial communities in the warm soils had undergone significant changes during the decade of the experiment, which facilitated their higher respiration rate. For instance, the study of the DNA of the microbes revealed found that the microbial communities of the warm plots had more genes related to carbon respiration than the microbes in the control plots.
"That was consistent with the idea that th
|Contact: Brett Israel|
Georgia Institute of Technology