Maui Rainfall Gradient- Trace Gas Production From Soils
Melanie
Vile
I am
examining controls on emission of three greenhouse gases, CH4, CO2 and nitrous
oxide from forested ecosystems along a rainfall gradient in Maui. We are
taking a thermodynamic approach to develop an integrated understanding of
mechanisms that control ecosystem-scale variations in trace gas emissions.
This approach follows from the observation that microbial communities compete
in a predictable manner for electron donors (e.g., organic C) and electron
acceptors (e.g., oxygen, nitrate, sulfate, etc.), following a thermodynamic
sequence of reactions. This sequence makes it possible to predict how specific
nutrient transformation and gaseous losses should vary within and among
ecosystems. The Hedin lab has recently developed a new 13CH4 isotope pool
dilution technique that allows us to simultaneously measure the balancing
processes of CH4 production and CH4 consumption in the same sample. Use
of this novel technique will allow us to more easily implement the thermodynamic
approach to examine how biophysical properties (i.e., heterogeneity) of
soils, such as moisture content and C availability, at the scale of microsites,
control both production and consumption of trace gases. Our goal is to bridge
the gap in translating microsite scales of control on trace gas emissions
to landscape scale patterns.
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