15N enrichment as an integrator of the effects of C and N on microbial metabolism and ecosystem function

  1. Paul Dijkstra1,*,
  2. Corinne M. LaViolette1,
  3. Jeffrey S. Coyle1,
  4. Richard R. Doucett2,
  5. Egbert Schwartz1,
  6. Stephen C. Hart3,4,
  7. Bruce A. Hungate1,4

Article first published online: 12 FEB 2008

DOI: 10.1111/j.1461-0248.2008.01154.x

Issue

Ecology Letters

Ecology Letters

Volume 11, Issue 4, pages 389–397, April 2008

Additional Information

How to Cite

Dijkstra, P., LaViolette, C. M., Coyle, J. S., Doucett, R. R., Schwartz, E., Hart, S. C. and Hungate, B. A. (2008), 15N enrichment as an integrator of the effects of C and N on microbial metabolism and ecosystem function. Ecology Letters, 11: 389–397. doi: 10.1111/j.1461-0248.2008.01154.x

Author Information

  1. 1

    Department of Biological Sciences, Northern Arizona University, P.O. Box 5640, Flagstaff, AZ 86011, USA

  2. 2

    Colorado Plateau Stable Isotope Laboratory, Northern Arizona University, P.O. Box 5640, Flagstaff AZ 86011, USA

  3. 3

    School of Forestry, Northern Arizona University, P.O. Box 15018, Flagstaff AZ 86011, USA

  4. 4

    Merriam-Powell Center for Environmental Research, Northern Arizona University, P.O. Box 5640, Flagstaff, AZ 86011, USA

* *E-mail: paul.dijkstra@nau.edu

Publication History

  1. Issue published online: 12 FEB 2008
  2. Article first published online: 12 FEB 2008
  3. Editor, Johannes Knops Manuscript received 15 October 2007 First decision made 20 November 2007 Second decision made 11 December 2007 Manuscript accepted 22 December 2007

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Keywords:

  • δ15Ν;
  • carbon and nitrogen availability;
  • ecosystem function;
  • N cycling;
  • N mineralization;
  • resource availability;
  • soil microbial biomass;
  • stable isotopes

Abstract

Organic carbon (C) and nitrogen (N) are essential for heterotrophic soil microorganisms, and their bioavailability strongly influences ecosystem C and N cycling. We show here that the natural 15N abundance of the soil microbial biomass is affected by both the availability of C and N and ecosystem N processing. Microbial 15N enrichment correlated negatively with the C : N ratio of the soil soluble fraction and positively with net N mineralization for ecosystems spanning semiarid, temperate and tropical climates, grassland and forests, and over four million years of ecosystem development. In addition, during soil incubation, large increases in microbial 15N enrichment corresponded to high net N mineralization rates. These results support the idea that the N isotope composition of an organism is determined by the balance between N assimilation and dissimilation. Thus, 15N enrichment of the soil microbial biomass integrates the effects of C and N availability on microbial metabolism and ecosystem processes.

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