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AGU: Global Biogeochemical Cycles

 

Index Terms

  • Geochemistry: Isotopic composition/chemistry
  • Global Change: Biogeochemical processes
  • Hydrology: Soil moisture
  • Meteorology and Atmospheric Dynamics: Land/atmosphere interactions
Abstract
Cited By (43)
 

Abstract

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

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 (δ15Nplant15Nsoil) 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.

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.

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