Friday, August 10, 2007 - 9:20 AM

COS 162-5: A trail of isotopes from food webs to ecosystems

Paul Dijkstra, Jeffrey S. Coyle, Corinne M. LaViolette, Paul C. Selmants, Egbert Schwartz, Stephen C. Hart, and Bruce A. Hungate. Northern Arizona University

Stable isotopes are helpful in relating metabolic processes to ecosystem properties. Animals show characteristic 15N enrichments relative to their diet, but this enrichment is variable. The cause for this variability is not well known. The soil microbial biomass is likewise 15N enriched relative to the soil total and soluble N fraction, and this enrichment is also variable. However, we find that this microbial 15N enrichment is related to C and N availability for soils from semiarid to temperate and tropical climates, grasslands and forests and over 4 million years of ecosystem development. A similar relationship is observed between 15N enrichment of animals and the C:N ratio of their diet. We will discuss why this relationship exists and how 15N enrichment reveals metabolic processing throughout food webs, N cycling and is reflected in the stable soil organic matter.

See more of COS 162 - Stable isotope and tracer applications
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