Climate Change May Affect Microbe Functions

Global climate change will affect bacteria, fungi, and other microbial populations that perform a myriad of functions important to life on Earth. It is not entirely certain what those effects will be, but they could be significant and will probably not be good, say researchers on June 3 at a scientific meeting in Boston.

Kathleen Treseder of the University of California, Irvine, studied the effect of rising temperatures and fungi on carbon stores in Alaskan boreal forests. "There is a lot of frozen dead material under the snowpack," Treseder told the 108th General Meeting of the American Society for Microbiology. "There is as much carbon trapped in the soil of northern ecosystems as there is carbon in the atmosphere. It is a big unknown what is going to happen if these environments heat up," she added.

Her original hypothesis was that an increase in temperatures would lead to increased decomposition by fungi. Since one byproduct of decomposition is carbon dioxide, rising temperatures should result in greater carbon dioxide release from the soil. What she found was that nitrogen levels in the soil increased as temperatures rose, and nitrogen tends to suppress fungal decomposition rates.

Rising temperatures are having an effect on snowpack and glaciers and that could be detrimental to the communities of microorganisms living below them. Steven Schmidt from the University of Colorado and his colleagues have been studying the diverse populations of microorganisms that make their home in the sub-freezing zone underneath glaciers.

"As global temperatures rise and glaciers retreat, these microorganisms lose their habitat. They will probably go extinct before we can study them and get a better idea of their contributions," said Schmidt.

He is studying microbial activity under the snowpack in coniferous forests. Undersnow microbial activity is especially high in the late winter as the snowpack provides ideal temperatures and moisture for the growth of mats of snow mold. To the average suburban dweller, snow mold may just be another disease that damages the lawn, but in the coniferous forest ecosystem, these mats serve an important function.

"Snow mold are extremely rapidly growing at very low temperatures – below freezing and contribute about 10-30 percent of the total year-round carbon dioxide production at these sites" he said.

Snow mold needs a period of a month or two at relatively low temperatures to do its job effectively. As global temperatures rises the late winter period of subfreezing temperatures will shorten, and snowpacks may be less as well.

"As the soils warm, snow molds will have less water and will produce less carbon dioxide, which may sound good in terms of global warming, but the trees in this system also depend on snow melt water and will ultimately die under extreme drought, thus leading to an overall decrease in carbon fixation by the system. The trees may die. Overall, its probably going to be bad," Schmidt said.

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