Global patterns of the isotopic composition of soil and plant nitrogen

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Read Full Article (file size: 389363 bytes) Cited by GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 17, NO. 1, 1031, doi:10.1029/2002GB001903, 2003 Global patterns of the isotopic composition of soil and plant nitrogen Ronald Amundson Division of Ecosystem Sciences, University of California, Berkeley, Berkeley, California, USA A. T. Austin Facultad de Agronomía, Cátedra de Ecología, Universidad de Buenos Aires, Buenos Aires, Argentina E. A. G. Schuur Department of Earth System Science, University of California, Irvine, Irvine, California, USA K. Yoo Division of Ecosystem Sciences, University of California, Berkeley, Berkeley, California, USA V. Matzek Division of Ecosystem Sciences, University of California, Berkeley, Berkeley, California, USA C. Kendall Water Resources Division, U.S. Geological Survey, Menlo Park, California, USA A. Uebersax Division of Ecosystem Sciences, University of California, Berkeley, Berkeley, California, USA D. Brenner Division of Ecosystem Sciences, University of California, Berkeley, Berkeley, California, USA W. T. Baisden Division of Ecosystem Sciences, University of California, Berkeley, Berkeley, California, USA Abstract We compiled new and published data on the natural abundance N isotope composition (δ¹⁵N values) of soil and plant organic matter from around the world. Across a broad range of climate and ecosystem types, we found that soil and plant δ¹⁵N values systematically decreased with increasing mean annual precipitation (MAP) and decreasing mean annual temperature (MAT). Because most undisturbed soils are near N steady state, the observations suggest that an increasing fraction of ecosystem N losses are ¹⁵N-depleted forms (NO₃, N₂O, etc.) with decreasing MAP and increasing MAT. Wetter and colder ecosystems appear to be more efficient in conserving and recycling mineral N. Globally, plant δ¹⁵N values are more negative than soils, but the difference (δ¹⁵N_plant-δ¹⁵N_soil) increases with decreasing MAT (and secondarily increasing MAP), suggesting a systematic change in the source of plant-available N (organic/NH₄⁺ versus NO₃⁻) with climate. Nitrogen isotopes reflect time integrated measures of the controls on N storage that are critical for predictions of how these ecosystems will respond to human-mediated disturbances of the global N cycle. Published 27 March 2003. Index Terms: 1040 Geochemistry: Isotopic composition/chemistry; 1615 Global Change: Biogeochemical processes (4805); 1866 Hydrology: Soil moisture; 3322 Meteorology and Atmospheric Dynamics: Land/atmosphere interactions. Read Full Article (file size: 389363 bytes) Cited by Citation: Amundson, R., A. T. Austin, E. A. G. Schuur, K. Yoo, V. Matzek, C. Kendall, A. Uebersax, D. Brenner, and W. T. Baisden (2003), Global patterns of the isotopic composition of soil and plant nitrogen, Global Biogeochem. Cycles, 17(1), 1031, doi:10.1029/2002GB001903. Copyright 2003 by the American Geophysical Union.

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