New insights into the global patterns of the isotopic composition of soil and plant nitrogen

Background/Question/Methods

Models of N cycling in soils and ecosystems predict climatically and geographically controlled spatial distributions of N concentrations and storage, patterns that have been empirically confirmed over many decades.  Similarly, related models that incorporate stable isotope ratios of inputs and outputs suggest landscape patterns that are now being observationally examined with greater frequency as the measurement of stable N isotopes has become more common in the earth and ecosystem science communities. More than a decade has passed, and dozens of subsequent studies have been made, since initial hypotheses about landscape patterns of soil and plant d¹⁵N values were first made (1). This enormous wealth of new data allows for a significant improvement in defining N isotope spatial patterns, and creates opportunities for subsequent refinements in our understanding of the processes and models that can describe them. 

Results/Conclusions

The purpose of this presentation is to summarize the results of this new work, and examine the implications of the refinements it provides for our understanding of the terrestrial N cycle and its response to anthropogenic stress.

(1) 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 Biogeochemical Cycles. 17(1), 1031, doi: 10, 1029/2002GB001903.