Department of Environmental Sciences

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Seminar Abstracts
Environmental Sciences Seminar Abstract            

  Elevated Atmospheric Carbon Dioxide Alters Terrestrial and Aquatic Microbial Communities in a Temperate Forest
John Kelly

Global atmospheric CO2 levels are increasing due to the burning of fossil fuels and changes in land use patterns and are expected to double within the next 50 years. The impacts of CO2 enrichment on plants have been studied extensively for over 20 years, but the potential impacts on microbial communities are not as well understood. Microbes are critical components of the global carbon cycle, so understanding microbial responses is essential to understanding the ecological impacts of increasing atmospheric CO2. The goal of our project was to investigate the impacts of CO2 enrichment on microbial communities in a temperate forest. Although elevated CO2 would not be expected to directly impact terrestrial or aquatic microbial communities in a temperate forest, we hypothesized that the microbes would be affected by plant responses to CO2 enrichment. To test this hypothesis we grew trembling aspen (Populus tremuloides) trees outdoors under either elevated (720ppm, ELEV) or ambient CO2 (360ppm, AMB) for five years. We profiled the microbial communities in the soils below the trees using molecular tools including phospholipid fatty acid (PLFA) analysis, terminal restriction fragment length polymorphism (T-RFLP) analysis, quantitative real-time PCR (Q-PCR), and clone library sequencing, and we found some significant shifts in microbial community composition with ELEV treatment. We also incubated leaves from AMB and ELEV trees in a woodland stream for 14 days and profiled the microbial communities colonizing the leaves using similar approaches. We found significant shifts in the size and composition of microbial communities colonizing the ELEV leaves. Our results indicate that CO2 enrichment does impact microbial communities in terrestrial and aquatic habitats within a temperate forest in ways that could have significant implications for these ecosystems.

Last updated: 04/21/2009