Soil Respiration and Microbial Diversity in a Subalpine Forest

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We will investigate the causes of high versus low rates of respiration (CO2 loss) by soil microorganisms (fungi and bacteria) in a subalpine forest ecosystem in Colorado. Soil respiration is one of the dominant processes affecting ecosystem carbon balance, and thus affecting the capacity for ecosystems to absorb carbon dioxide that is emitted to the atmosphere from fossil fuel and biomass burning. In the subalpine forest ecosystem of Colorado, soil respiration is responsible for returning 40-60% of the CO2 that is absorbed by the photosynthetic trees of the forest, to the atmosphere each year. It is likely that this value changes significantly from wet to dry years and in response to long-term climate warming. We will seek to understand why it changes so much by studying changes in the soil microorganisms that release the CO2 in response to spatial and temporal variation. We will combine modern DNA "fingerprinting" techniques to determine which, and how many, microorganisms are present at any point in time and at any point in space, and the magnitude of soil respiration associated with those organisms. We will also study the influences of simulated treatments for long-term climate change in the form of warming lamps and altered snow pack to determine the response of soil respiration rate to climate change, and the causes of such responses due to changes in the diversity and amounts of microorganisms. overall, the research will provide us with an improved understanding of soil microorganism dynamics and their relationship to soil respiration, one of the critical components of the global carbon cycle.The studies will provide for the training of two graduate students through Research Assistant support, and they will significantly advance the development of techniques to probe soil samples for the presence of microorganisms. This latter capability may turn out to be very useful to future efforts in Homeland Security, especially with regard to detecting trace amounts of potentially dangerous microorganisms. The grant will also support the career of a beginning faculty member (David Lipson) at San Diego State University.