Unraveling the Role of Soil Moisture As a Driver of Soil Oxygen Variation: A Sensor Network Approch.

There are few measurements of soil oxygen, particularly for argicultural soils and wetland ecosystems.  This lack of data is surprising given the recognized importance of oxygen as a driver of biogeochemical activity and microbial community composition.  We are particularly interested in measuring soil oxygen in agricultural soils being converted to wetlands because of its effects on th production of many greenhouse gases.  Changes in a soil’s oxygen content will affect the rates of  many soil processes, yet we do not know how much soil oxygen levels vary or what the principle controls are.  We expect soil oxygen will fluctuate due to changes in temperature, soil moisture/precipitation regime/climate (humidity), and may also be influenced by the degree of geochemical (mineral oxidation) activity.  Herein, we present preliminary data (~6 months) from a sensor network designed to quantify variation in soil oxygen concentrations vary in response to these drivers.   Our sensor network was deployed in a formerly agricultural field undergoing restoration to a wetland; these agricultural soils were in production for >100 years. To test our hypotheses, we will measure methane, nitrous oxide and carbon dioxide fluxes as well as carbon storage (the balance between plant growth and decomposition) in relation to soil oxygen dynamics pre- and post-wetland construction.  The balance between these emitting and sequestering processes underpins our knowledge of how biogeochemical services operate in created wetlands, and thus if created wetlands will attain the same carbon storage capacity as natural wetlands.  Understanding both the timing and mechanisms of emitting and sequestration processes are critical to predicting if a wetland will be a net greenhouse gas source or sink.