In partial fulfillment of the requirements for the degree of

Doctor of Philosophy in Biology

In the

School of Biological Sciences

Tianze Song

Will defend his dissertation

The response of the microbial carbon cycle and greenhouse gas production in wetland soils to climate change drivers

6th Dec 2022

11:00 AM

ES&TT L1205

https://gatech.zoom.us/j/6732505536

Thesis Advisor:

Joel Kostka, Ph.D.

School of Biological Sciences

Georgia Institute of Technology

Committee Members:

Thomas Dichristina, Ph.D.

School of Biological Sciences

Georgia Institute of Technology

Martial Taillefert, Ph.D.

School of Earth and Atmospheric Sciences

Georgia Institute of Technology

Caitlin Petro, Ph.D.

School of Biological Sciences

Georgia Institute of Technology

Christopher Schadt, Ph.D.

Biosciences Division

Oak Ridge National Laboratory

ABSTRACT: Although comprising only ~3% of the terrestrial surface area, peatland ecosystems store an estimated one-third soil carbon. In addition to this role as a critical global carbon sink, freshwater wetlands, such as peatlands, account for approximately one-third of global methane (CH4) emissions to the atmosphere. While CH4 emissions from peatlands are expected to disproportionately increase due to warming, the environmental controls remain poorly constrained. Any increase in CH4 emission is of great concern due to the fact that the sustained-flux global warming potential of CH4 is estimated to be 34-times greater than that of carbon dioxide (CO2) on a 100 y timescale.
 
We are investigating how soil microbial communities respond to climate change factors, warming and elevated atmospheric CO2, in the laboratory and under in situ conditions.  Our research indicates that soil organic matter quality or composition is a primary driver of greenhouse gas production from heterotrophic respiration and methanogenesis in soils across many peatland types. In particular, we show that dissolved organic carbon (DOC) compounds inhibit microbial-mediated decomposition and greenhouse gas production, but the inhibitory effect is alleviated by warming.  Warming leads to a decline in phylogenetic diversity and pronounced shifts in the composition of microbial communities, with implications for ecosystem function.  Our results suggest that with warming, we can expect a concomitant shift toward increasingly methanogenic conditions and amplified climate–peatland feedbacks.