Transport of root-respired CO2 via the transpiration stream affects aboveground carbon assimilation and CO2 efflux in trees
Article first published online: 11 OCT 2012
© 2012 The Authors. New Phytologist © 2012 New Phytologist Trust
Volume 197, Issue 2, pages 555–565, January 2013
How to Cite
Bloemen, J., McGuire, M. A., Aubrey, D. P., Teskey, R. O. and Steppe, K. (2013), Transport of root-respired CO2 via the transpiration stream affects aboveground carbon assimilation and CO2 efflux in trees. New Phytologist, 197: 555–565. doi: 10.1111/j.1469-8137.2012.04366.x
- Issue published online: 18 DEC 2012
- Article first published online: 11 OCT 2012
- Manuscript Accepted: 31 AUG 2012
- Manuscript Received: 24 MAY 2012
- Special Research Fund (B.O.F.)
- U.S. National Science Foundation. Grant Number: 1021150
- carbon allocation;
- soil CO2 efflux;
- stable isotope;
- xylem transport
- Upward transport of CO2 via the transpiration stream from belowground to aboveground tissues occurs in tree stems. Despite potentially important implications for our understanding of plant physiology, the fate of internally transported CO2 derived from autotrophic respiratory processes remains unclear.
- We infused a 13CO2-labeled aqueous solution into the base of 7-yr-old field-grown eastern cottonwood (Populus deltoides) trees to investigate the effect of xylem-transported CO2 derived from the root system on aboveground carbon assimilation and CO2 efflux.
- The 13C label was transported internally and detected throughout the tree. Up to 17% of the infused label was assimilated, while the remainder diffused to the atmosphere via stem and branch efflux. The largest amount of assimilated 13C was found in branch woody tissues, while only a small quantity was assimilated in the foliage. Petioles were more highly enriched in 13C than other leaf tissues.
- Our results confirm a recycling pathway for respired CO2 and indicate that internal transport of CO2 from the root system may confound the interpretation of efflux-based estimates of woody tissue respiration and patterns of carbohydrate allocation.