SREL Reprint #3453

Respiration and CO2 Fluxes in Trees

Robert O. Teskey1, Mary Anne McGuire1, Jasper Bloemen2, Doug P. Aubrey3, and Kathy Steppe4

1Warnell School of Forestry and Natural Resources, University of Georgia,
180 E. Green Street, Athens, GA 30602, USA
2Department of Biology, Centre of Excellence PLECO, University of Antwerp,
Campus Drie Eiken, Universiteitsplein 1, B2610, Antwerp, Belgium
3Savannah River Ecology Laboratory, University of Georgia, PO Drawer E, Aiken, SC 29802, USA
4Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology,
Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium

Summary: Currently, the most pressing problem regarding respiration in trees is determining the rate of respiration in woody tissues. Respiration is relatively easily measured in isolated cells by measuring the evolution of CO2, but this measurement becomes much more complicated in intact tree roots, stems and branches because CO2 moves readily into xylem sap where it can remain, or be refixed by photosynthetic cells in woody tissues, or moved from the site of production through the xylem. Carbon dioxide is continuously diffusing from the xylem sap into the atmosphere as xylem sap moves through the tree. Fortunately, many research groups have been addressing these issues using a variety of experimental protocols. In this review we will examine the progress that has been made since 2008, the last time this topic was reviewed. One of the most important findings in that period of time has been that a large quantity of the CO2 found in tree stems can come from the root system. This means that root respiration can be substantially underestimated by “soil-centric” measurements. We discuss new methods to measure and model stem respiration and the use of recently produced carbohydrates for woody tissue respiration. We also discuss woody tissue photosynthesis and the quantity of CO2 that can be internally recycled within trees, a process that may be particularly important for tree survival during periods of drought but has received little attention. Finally, the research summarized in this chapter illustrates that, at the whole plant level, physiological activity involves both cellular and higher order transport processes that add a level of complexity to how we measure and interpret apparent respiration rates.

SREL Reprint #3453

Teskey, R. O., M. A. McGuire, J. Bloemen, D. P. Aubrey, and K. Steppe. 2017. Respiration and CO2 Fluxes in Trees. pp. 181-207 In: G. Tcherkez and J. Ghashghaie (Eds.). Plant Respiration: Metabolic Fluxes and Carbon Balance. Springer International Publishing.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).