Show simple item record

dc.contributor.advisorFinzi, Adrienen_US
dc.contributor.authorSaifuddin, Mustafaen_US
dc.date.accessioned2019-04-25T17:31:36Z
dc.date.available2019-04-25T17:31:36Z
dc.date.issued2019
dc.identifier.urihttps://hdl.handle.net/2144/34934
dc.description.abstractSoil bacteria and fungi play a central role in the biogeochemical cycling of both carbon (C) and nitrogen (N) through terrestrial ecosystems. In the C cycle, soil microbial groups regulate the depolymerization of large stocks of soil organic matter and contribute 35-69 Pg C to the atmosphere annually through heterotrophic respiration. Soil microbial groups also mediate several important transformations of N, including making limiting nutrients available for uptake by plants through N-fixation, converting N between inorganic forms through nitrification, and returning N to the atmosphere through denitrification. While each of these functions is performed by soil microbes, scaling microbial physiology and community structure to biogeochemical cycling remains a significant research challenge. This dissertation integrates three distinct approaches to characterizing relationships between microbial physiology, microbial community structure and biogeochemical cycling. First, I explore the role of microbial physiology in C cycling by developing a novel method to predict bacterial carbon use efficiency (CUE) from genomes using metabolic modeling. I find that bacterial CUE is phylogenetically structured, with the class and order levels explaining the greatest proportion of variance in CUE, and I identify particular bacterial traits that most strongly predict CUE. These findings highlight the importance of accounting for microbial physiology when modeling soil C cycling. Second, I explore how differences in the abundance and activity of microbial functional groups and their interactions with mycorrhizal fungi impact temperate forest N cycling. I find that N availability and rates of N-fixation, nitrification and denitrification are structured in relation to mycorrhizal fungal types, but that the abundances of bacterial functional groups are not correlated with biogeochemical fluxes. Finally, I use a soil biogeochemical model to identify sources of uncertainty and data needs in advancing our understanding of microbially-mediated soil biogeochemical cycling. I isolate specific microbial physiological and enzyme kinetic parameters that have disproportionately large impacts on projections of coupled C and N cycling, and I quantify the potential for particular types of data to help reduce uncertainties. Overall, this dissertation advances our understanding of how microbial processes impact the biogeochemical cycling of C and N in terrestrial ecosystems.en_US
dc.language.isoen_US
dc.subjectEcologyen_US
dc.subjectBiogeochemistryen_US
dc.subjectCarbonen_US
dc.subjectMicrobial physiologyen_US
dc.subjectNitrogenen_US
dc.subjectSoilen_US
dc.titleRelationships between soil microbial physiology, community structure and carbon and nitrogen cycling in temperate forest ecosystemsen_US
dc.typeThesis/Dissertationen_US
dc.date.updated2019-04-15T01:00:24Z
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineBiologyen_US
etd.degree.grantorBoston Universityen_US


This item appears in the following Collection(s)

Show simple item record