NRESS PhD Program Fall 2018 Environmental Sciences Seminar Series presents
"This Microbial Life: New Perceptions of our Microbial World", a miniseries within the seminar series. We welcome the first of four speakers in this miniseries:
Dr. Marco Keiluweit, Assistant Professor, Soils and the Environment, Stockbridge School of Agriculture, University of Massachusetts-Amherst
Spatial Variations in Microbial Processes Controlling
Carbon Oxidation Rates in Soils
Soils represent
the largest and most dynamic carbon reservoir within terrestrial
ecosystems. Mechanisms controlling the amount of carbon stored in soils
and its feedbacks to the climate system, however, remain poorly resolved.
Global carbon models assume that carbon cycling in upland soils is entirely
driven by aerobic heterotrophic respiration; the impact of anaerobic microsites
prevalent even within well-drained upland soils is missed within this
conception. In this presentation, I will show that anaerobic microsites,
ubiquitous in even well-drained upland soils, are important regulators of soil
carbon persistence. I will demonstrate that microbial metabolism in anaerobic
microsites shifts to less efficient anaerobic respiration, thereby protecting
otherwise bioavailable, reduced organic compounds from decomposition. I will
further explain how such metabolic constraints may be responsible for the
selective preservation of aliphatic compounds such as lipids and waxes observed
in upland soils globally. Finally, I will discuss the vulnerability of
anaerobically protected soil carbon to future climate or land use change and
argue that it constitutes a yet unrecognized positive soil carbon-climate
feedback mechanism that should be quantitatively incorporated into terrestrial
ecosystem climate models.