Nitrous Oxide Emission from Forest, Marsh, and Prairie Ecosystems

Abstract Measurements of N 2 O emissions from seven natural ecosystem sites in the University of Wisconsin Arboretum (Madison, WI) were conducted during 1979, 1980, and early 1981. Nitrous oxide emissions during summer and autumn 1979 averaged 0.6, 0.7, 1.5, 7.7, 18.0, 0.2, and 8.5 ng N 2 O‐N in m −2 s −1 from a burned and an unburned tall‐grass prairie, a deciduous forest, a coniferous forest, a drained and an undrained marsh, and a wet meadow, respectively; the N 2 O fluxes from the same sites from March to November 1980 averaged 0.6, 0.6, 4.3, 10.1, 41.3, 0.3, and 8.5 ng N 2 O‐N m −2 s −1 , respectively. Although soil temperatures were near freezing, N 2 O emissions were as high during the spring thaw as they were during the rest of the year. Other N 2 O flux maxima were observed following periods of heavy rainfall during the summer. The source of inorganic N in these soils is largely mineralization of soil organic matter and plant residue. The quantities of N 2 O lost and the mechanisms responsible for N 2 O evolution are a complex combination of environmental and substrate conditions that control mineralization of N as well as subsequent nitrification and possibly denitrification.