N₂O and CO₂ fluxes from soils in response to nitrogen addition: Are there any differences between forests, agro-ecosystems, and coastal wetlands?

Nitrous oxide (N₂O) is a powerful greenhouse gas but its temporal and spatial variations and the coupling with CO₂ production from forest ecosystems, agroecosystems, and coastal wetlands are not well understood. We developed an integrated system to measure in situ CO₂ and N₂O fluxes from different ecosystems. This system consists of recently developed laser-based gas analyzers with the new cavity ring down spectroscopy technique to measure CO₂ and N₂O. These analyzers were connected to a closed chamber system that enables flux measurement within a five-minute cycle. The response of CO₂ and N₂O fluxes to nitrogen addition in a forest ecosystem, agricultural field, and saltmarsh in New England was compared. We found that both N₂O and CO₂ flux esresponded significantly to soil water content and N availability. We will then develop a model to simulate CO₂ and N2O fluxes as a function of C stock, N stock, soil temperature, and soil water content.