Sep. 5, 2003 A new University of Colorado at Boulder study has shown that microbes living under the tundra snow pack ramp up their populations in late winter, a finding with implications for changing estimates of carbon dioxide levels in Earth's atmosphere.
According to CU-Boulder Professor Steve Schmidt, the abundance of microbes under the snow -- primarily previously unknown groups of fungi-- is at its highest in the late winter months, breaking down organic and inorganic material and recycling carbon and nitrogen. "This is important because these microbes may increase the release of CO2 into the atmosphere and could change estimates of carbon fluctuation on Earth," he said.
The results are prompting a reevaluation by scientists of whether snow-covered regions can act as "sinks," or storage areas, for CO2, he said.
A paper on the subject by Schmidt, Christopher Schadt and Andrew Martin from CU-Boulder and David Lipson from San Diego State University will appear in the Sept. 5 issue of Science magazine.
About 40 percent of Earth's terrestrial environment is covered by snow for varying lengths of time in the winter months, said Schmidt, a professor in the ecology and evolutionary biology department who led the study. "The amount of microbial activity is probably very high in places like Canada, Alaska and Siberia that have enormous amounts of snow pack over large areas for extended periods."
In analyzing the cold tundra soil on Niwot Ridge west of Boulder, the researchers discovered several major new groups of fungi using sophisticated DNA sequencing methods, he said. "An abundance of previously unknown fungi that are active beneath the snow substantially broadens our understanding of both the diversity and biogeochemical functioning of fungi in cold environments," the researchers wrote in Science.
The types of fungi and other microbes under the snow in winter and spring on Niwot Ridge are different than microorganisms found in the cold soils during the summer months, said Schmidt. "Microbes produce many generations over the course of a year, and the winter microbes probably either go dormant or die during the summer," he said.
Located just east of the Continental Divide at elevations from roughly 10,000 feet to 12,000 feet, Niwot Ridge is the only long-term alpine and sub-alpine study site on the continent.
Funded by the National Science Foundation and administered by CU-Boulder's Institute of Arctic and Alpine Research, Niwot Ridge is one of only 20 sites in North America designated as a Long-Term Ecological Research site. Niwot Ridge encompasses several thousand acres of tundra, talus slopes, glacial lakes and wetlands.
"The presence of previously unknown, higher order lineages of fungi in tundra soils suggests that the cold, snow-covered soils may be an underappreciated repository of biological diversity," the researchers wrote in Science.
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