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Research

Current research projects include studies of 1) ecosystem-atmosphere CO2 and H2O exchange at AmeriFlux sites and 2) trophic linkage in coastal water systems. We are also investigating soil nutrient cycling and vegetation dynamics in salt marsh ecosystems in coastal San Diego.

1) Ecosystem-atmosphere H2O exchange

This NSF project aims to establish a premium water isotope research station with high quality, frequent and uninterrupted atmospheric vapor isotope (2H and 18O) measurements to investigate vapor isotope fractionation and its applications on ecosystem-atmosphere water and CO2 exchange. The proposed research builds upon current understanding of water vapor isotopic fractionation under the influence of vegetation-atmosphere interaction. This project will evaluate a number of critical assumptions in hydrospheric isotope models, identify key fractionation processes, and develop mechanistic algorithms to address caveats that mask the potential of hydrogen and oxygen isotope tracers in hydrological and carbon cycle research. This research is conducted at an AmeriFlux site Wind River Field Station in southern Washington.

2) Ecosystem-atmosphere CO2 exchange

An atmospheric isotope network that presents a continuous, long-term record of isotope changes relating to CO2 and water exchange on land. These isotope measurements provide an excellent opportunity to study ecosystem response to climate change as the data stream grows in time. We are measuring stable isotope composition of atmospheric CO2 in whole air samples at ten AmeriFlux sites. Our two DOE-sponsored projects provide the basis for an AmeriFlux-isotope network that include major biomes in contiguous USA.