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15 N enrichment as an integrator of the effects of C and N on microbial metabolism and ecosystem function
Author(s) -
Dijkstra Paul,
LaViolette Corinne M.,
Coyle Jeffrey S.,
Doucett Richard R.,
Schwartz Egbert,
Hart Stephen C.,
Hungate Bruce A.
Publication year - 2008
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/j.1461-0248.2008.01154.x
Subject(s) - ecosystem , mineralization (soil science) , nitrogen cycle , ecology , terrestrial ecosystem , biomass (ecology) , microorganism , environmental chemistry , biogeochemical cycle , soil biology , biology , environmental science , agronomy , chemistry , soil water , nitrogen , bacteria , genetics , organic chemistry
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 15 N abundance of the soil microbial biomass is affected by both the availability of C and N and ecosystem N processing. Microbial 15 N 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 15 N 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, 15 N enrichment of the soil microbial biomass integrates the effects of C and N availability on microbial metabolism and ecosystem processes.