Events

October 1, 2017 at 7:15 pm

Plant Biology Colloquium | Don’t Miss the Microbes for the Trees, Oct. 20

The Environmental & Plant Biology Colloquium Series presents Dr. Zachary Freedman on “Don’t Miss the Microbes for the Trees: A Potential Mechanism Fostering Ecosystem C Storage under Future Rates of N Deposition” on Friday, Oct. 20, at 11:50 a.m. in Porter 104.

Dr. Zachary Freedman

Dr. Zachary Freedman

Freedman is an Assistant Professor in the School of Agriculture and Food, Division of Plant and Soil Sciences, at West Virginia University

Abstract: Soil organic matter (SOM) decomposition is a globally important and enzymatically-complex biogeochemical process. It is mediated by a diverse assemblage of saprophytic microorganisms, and can be suppressed by anthropogenic N deposition. In a northern hardwood forest ecosystem in Michigan, USA, twenty years of experimentally increased N deposition has reduced forest floor decay and increased soil C storage (+18%). Here, we paired extracellular enzyme assays with high-throughput DNA sequencing and shotgun metagenomics to determine if anthropogenic N deposition has altered the functional potential of microbial communities to degrade SOM in our long-term field experiment. Experimental N deposition reduced lignocellulolytic enzyme activity and changed the metagenomic composition of the microbial community inhabiting decaying forest floor, providing indirect evidence that compositional shifts elicited a functional response in our long-term field experiment. The activity of extracellular enzymes mediating plant litter and humus decay, cellobiohydrolase and peroxidase, were ~50% lower under experimental N deposition. Experimental N deposition significantly affected the relative abundances of genes associated with 58 of 177 pathways within the Carbohydrates, Metabolism of Aromatic Compounds (MAC), and Respiration Subsystems level 3 classifications, 44 of which increased in abundance between the ambient and experimental N deposition treatment. However, neither the abundance nor composition of fungal lignocellulolytic genes was impacted by experimental N deposition. Results presented here provide evidence that changes in the functional capacity of saprotrophic soil microorganisms may mediate how anthropogenic N deposition increases the storage of C in soil.

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