ESA/SER Joint Meeting (August 5 -- August 10, 2007)

Thursday, August 9, 2007: 9:00 AM

N, San Jose McEnery Convention Center

Jeffrey S. Coyle¹, Paul C. Selmants², Paul Dijkstra³, Egbert Schwartz¹, Stephen C. Hart⁴ and Bruce A. Hungate³, (1)Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, (2)Department of Natural Resources and Environmental Management, University of Hawaii at Manoa, Honlulu, HI, (3)Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, (4)Department of Life & Environmental Sciences, University of California, Merced, Merced, CA

We recently showed that the ¹⁵N enrichment of the microbial biomass, relative to the soil soluble fraction, correlates negatively with C and N availability and positively with net N mineralization. However, C and N availability and N mineralization rates have a high temporal variability. We investigated how C and N concentrations of the soil total, soluble and microbial pools and their respective δ¹⁵N isotope signature changed over time using a semiarid substrate age gradient in northern Arizona. We observed that although these variables changed significantly over time, the relationship between the ¹⁵N enrichment of the microbial biomass and the C and N availability was maintained. These results suggest that ¹⁵N enrichment of the microbial biomass may be a useful index of soil net N mineralization over time scales relevant to plant growth.

COS 111-4 - Temporal variability of 15N enrichment of the soil microbial biomass along a semiarid substrate age gradient

COS 111-4 - Temporal variability of¹⁵N enrichment of the soil microbial biomass along a semiarid substrate age gradient