Soil Microbial Community Structure and Its Influence On Soil Organic Matter (SOM) Decomposition.

Soil microorganisms are responsible for most decomposition and their responses to climate change will determine the impacts of warmer temperatures on ecosystem carbon stocks. A change in microbial functioning would have major impacts on carbon cycling and climate change feedbacks.  Yet most global change models and many experiments examining carbon cycle feedbacks fail to explicitly account for the impact of shifts in microbial community structure.  We were specifically interested in how microbial diversity and community structure affect decomposition ranges of a variety of soil organic matter (SOM) substrates under different temperature regimes. We used molecular tools to compare the microbial communities in soils following long-term incubation to those in fresh soil to determine how environmental controls have influenced soil microbial community structure and function. Following the 672 day incubation at 30C, 18-20% of the original total soil C was respired from our samples.  We expected to see a decrease in  the ability of microbes to decompose certain SOM compounds at lower temperatures and at oscillating temperatures and a decrease in the ability to degrade labile substrates.  The results from this work were intended to strengthen the link between environmental conditions,  microbial diversity/community structure, and ecosystem functioning. We believe that this work has important implications for understanding SOM responses to climate change and tools for forecasting those changes.

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See more from this Division: S03 Soil Biology & Biochemistry
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