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Relative stability of soil carbon revealed by shifts in δ15N and C:N ratio
1Institute of Environmental Geosciences, University of Basel, Bernoullistr. 30, 4056 Basel, Switzerland
2School of Geosciences, University of Edinburgh, Drummond Street, EH8 9XP Edinburgh, UK
3Research Station ART, Reckenholzstr. 191, 8046 Zürich, Switzerland
Abstract. Life on earth drives a continuous exchange of carbon between soils and the atmosphere. Some forms of soil carbon, or organic matter, are more stable and have a longer residence time in soil than others. Relative differences in stability have often been derived from shifts in δ13C (which is bound to a vegetation change from C3 to C4 type) or through 14C-dating (which is bound to small sample numbers because of high measurement costs). Here, we propose a new concept based on the increase in δ15N and the decrease in C:N ratio with increasing stability. We tested the concept on grasslands at different elevations in the Swiss Alps. Depending on elevation and soil depth, it predicted mineral-associated organic carbon to be 3 to 73 times more stable than particulate organic carbon. Analysis of 14C-ages generally endorsed these predictions.
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Citation: Conen, F., Zimmermann, M., Leifeld, J., Seth, B., and Alewell, C.: Relative stability of soil carbon revealed by shifts in δ15N and C:N ratio, Biogeosciences Discuss., 4, 2915-2928, 2007. Bibtex EndNote Reference Manager
