The diel imprint of leaf metabolism on the δ13C signal of soil respiration under control and drought conditions
Article first published online: 18 AUG 2011
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust
Volume 192, Issue 4, pages 925–938, December 2011
How to Cite
Barthel, M., Hammerle, A., Sturm, P., Baur, T., Gentsch, L. and Knohl, A. (2011), The diel imprint of leaf metabolism on the δ13C signal of soil respiration under control and drought conditions. New Phytologist, 192: 925–938. doi: 10.1111/j.1469-8137.2011.03848.x
- Issue published online: 11 NOV 2011
- Article first published online: 18 AUG 2011
- Received: 10 May 2011, Accepted: 7 July 2011
Vol. 202, Issue 4, 1412, Article first published online: 21 MAR 2014
- beech (Fagus sylvatica);
- diel cycle;
- laser spectroscopy;
- plant–soil interactions;
- pulse labeling;
- •Recent 13CO2 canopy pulse chase labeling studies revealed that photosynthesis influences the carbon isotopic composition of soil respired CO2 (δ13CSR) even on a diel timescale. However, the driving mechanisms underlying these short-term responses remain unclear, in particular under drought conditions.
- •The gas exchange of CO2 isotopes of canopy and soil was monitored in drought/nondrought-stressed beech (Fagus sylvatica) saplings after 13CO2 canopy pulse labeling. A combined canopy/soil chamber system with gas-tight separated soil and canopy compartments was coupled to a laser spectrometer measuring mixing ratios and isotopic composition of CO2 in air at high temporal resolution. The measured δ13CSR signal was then explained and substantiated by a mechanistic carbon allocation model.
- •Leaf metabolism had a strong imprint on diel cycles in control plants, as a result of an alternating substrate supply switching between sugar and transient starch. By contrast, diel cycles in drought-stressed plants were determined by the relative contributions of autotrophic and heterotrophic respiration throughout the day. Drought reduced the speed of the link between photosynthesis and soil respiration by a factor of c. 2.5, depending on the photosynthetic rate.
- •Drought slows the coupling between photosynthesis and soil respiration and alters the underlying mechanism causing diel variations of δ13CSR.