GDPE student Hannah Birge's MS Defense
Monday, July 16, 2012, 10:30 AM
NESB Building, Room B215

Decomposition of soil organic matter (SOM) is one of earth's most important and dynamic biogeochemical flows. However, the exact processes underlying the flow of SOM among soils pools and to the atmosphere remain unclear. Here, I investigated whether a depletion of the available SOM pool, soil microbial biomass or exo-enzyme pools drive the decline in soil respiration of the course of a long-term incubation. I found that the accessibility of available SOM was the key determinant of respiration, and the loss of microbial biomass and exo-enzymes over the course of a long-term incubation did not limit the remaining microbial biomass’ ability to respire accessible, available SOM. I observed a sharp increase in respiration when the soils were physically disrupted, supporting the idea that both availability and accessibility are key drivers of soil respiration. My results support a paradigm in which physico-chemical drivers of both flow into the available SOM pool and accessibility of available SOM control the rate of soil respiration over the course of a long-term incubation, when there exists a minimum threshold of microbial biomass and exoenzymes.

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Event Contact: Jeri Morgan can be reached at (970) 491-4373

Sponsored by the Graduate Degree Program in Ecology.