ABSTRACT

DEB-0508953 Dissertation Research: Does the impact of climate change on rates of soil N processing result in part from changes in microbial community composition?
Damon Bradbury and Mary Firestone, University of California, Berkeley
Global change is predicted to alter continental patterns of temperature and precipitation which will in turn impact soil microbial activity. This dissertation research project examines the impact of simulated climate change on microbial community composition and soil nitrogen (N) cycling. Microorganisms catalyze the major transformations of N in soils including the decomposition of leaves, wood and other organic matter. During decomposition processes, essential nutrients such as N are released as inorganic forms that are available to plants. Since N can be a limiting nutrient to plants in temperate systems, an understanding of the microbial processes that control availability of N in soils is important for understanding plant productivity and carbon retention in forests. Microbial N utilization also produces nitrous oxide, a greenhouse gas and a mediator of stratospheric ozone depletion. Understanding the relationship between the rates of N-cycling and the composition and physiological response characteristics of soil microbial communities will allow improved prediction of terrestrial ecosystem response to global environmental change as well as constituting a significant advancement in understanding the microbial basis of terrestrial ecosystem function. Doctoral Dissertation Improvement Grant funds will allow Damon Bradbury, a PhD candidate at University California at Berkeley, to use novel DNA microarray technology to analyze bacterial communities in Redwood Forest soils and perform chemical analyses to characterize the community physiological control over changes in N cycling dynamics that occur due to changes in moisture and temperature.

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