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Convergence of soil nitrogen isotopes across global climate gradients

February 6, 2015

Quantifying global patterns of terrestrial nitrogen (N) cycling is central to predicting future patterns of primary productivity, carbon sequestration, nutrient fluxes to aquatic systems, and climate forcing. With limited direct measures of soil N cycling at the global scale, syntheses of the 15 N: 14 N ratio of soil organic matter across climate gradients provide key insights into understanding global patterns of N cycling. In synthesizing data from over 6000 soil samples, we show strong global relationships among soil N isotopes, mean annual temperature (MAT), mean annual precipitation (MAP), and the concentrations of organic carbon and clay in soil. In both hot ecosystems and dry ecosystems, soil organic matter was more enriched in 15 N than in corresponding cold ecosystems or wet ecosystems. Below a MAT of 9.8°C, soil δ15N was invariant with MAT. At the global scale, soil organic C concentrations also declined with increasing MAT and decreasing MAP. After standardizing for variation among mineral soils in soil C and clay concentrations, soil δ15N showed no consistent trends across global climate and latitudinal gradients. Our analyses could place new constraints on interpretations of patterns of ecosystem N cycling and global budgets of gaseous N loss.

Citation Information

Publication Year 2015
Title Convergence of soil nitrogen isotopes across global climate gradients
DOI 10.1038/srep08280
Authors Joseph M. Craine, Andrew J. Elmore, Lixin Wang, Laurent Augusto, W. Troy Baisden, E. N. J. Brookshire, Michael D. Cramer, Niles J. Hasselquist, Erik A. Hobbie, Ansgar Kahmen, Keisuke Koba, J. Marty Kranabetter, Michelle C. Mack, Erika Marin-Spiotta, Jordan R. Mayor, Kendra K. McLauchlan, Anders Michelsen, Gabriela B. Nardoto, Rafael S. Oliveira, Steven S. Perakis, Pablo L. Peri, Carlos A. Quesada, Andreas Richter, Louis A. Schipper, Bryan A. Stevenson, Benjamin L. Turner, Ricardo A. G. Viani, Wolfgang Wanek, Bernd Zeller
Publication Type Article
Publication Subtype Journal Article
Series Title Scientific Reports
Series Number
Index ID 70140605
Record Source USGS Publications Warehouse
USGS Organization Forest and Rangeland Ecosystem Science Center