1. Present address: Licor Inc. Environmental, Lincoln, NE 68504, USA.
Tree photosynthesis modulates soil respiration on a diurnal time scale
Article first published online: 2 JUN 2005
Global Change Biology
Volume 11, Issue 8, pages 1298–1304, August 2005
How to Cite
Tang, J., Baldocchi, D. D. and Xu, L. (2005), Tree photosynthesis modulates soil respiration on a diurnal time scale. Global Change Biology, 11: 1298–1304. doi: 10.1111/j.1365-2486.2005.00978.x
- Issue published online: 15 JUN 2005
- Article first published online: 2 JUN 2005
- Received 9 September 2004; revised version received 22 February 2005 and accepted 24 February 2005
- carbon cycle;
- CO2 efflux;
- CO2 sensor;
- eddy covariance;
To estimate how tree photosynthesis modulates soil respiration, we simultaneously and continuously measured soil respiration and canopy photosynthesis over an oak-grass savanna during the summer, when the annual grass between trees was dead. Soil respiration measured under a tree crown reflected the sum of rhizosphere respiration and heterotrophic respiration; soil respiration measured in an open area represented heterotrophic respiration. Soil respiration was measured using solid-state CO2 sensors buried in soils and the flux-gradient method. Canopy photosynthesis was obtained from overstory and understory flux measurements using the eddy covariance method. We found that the diurnal pattern of soil respiration in the open was driven by soil temperature, while soil respiration under the tree was decoupled with soil temperature. Although soil moisture controlled the seasonal pattern of soil respiration, it did not influence the diurnal pattern of soil respiration. Soil respiration under the tree controlled by the root component was strongly correlated with tree photosynthesis, but with a time lag of 7–12 h. These results indicate that photosynthesis drives soil respiration in addition to soil temperature and moisture.