Determining the Importance of an Internal Pathway for Root-Respired CO2

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

Robert O'Neal Teskey IOS-1021150 Determining the Importance of an Internal Pathway for Root-Respired CO2 This project will test whether below ground respiration in forests has been substantially underestimated because of an unaccounted-for pathway for the movement of carbon dioxide through roots. It is possible that a large amount of carbon dioxide does not diffuse directly into the atmosphere after it is released from respiration, but instead dissolves in xylem sap and is transported internally within trees, moving upward into the stem with the transpirational demand for water. The investigators will test this hypothesis by using ecophysiological approaches to measure the quantity of carbon dioxide released by root respiration and estimate total below ground respiration over the course of a year in a stand of Eastern cottonwood trees (Populus deltoides). The researchers will then determine the quantity of below ground-derived carbon dioxide that diffuses from above ground tissues into the atmosphere and will measure the amount of the carbon dioxide that is re-fixed by photosynthesis in above ground tissues. If a significant amount of carbon dioxide moves internally from the root system in the transpiration stream, the process will change our current understanding of tree and forest carbon cycles. In addition, re-fixation of the transported carbon dioxide will provide evidence of a carbon recycling mechanism in trees. The investigators will use this project as a platform to teach K-12 students about the carbon cycle and to train environmental educators. The project will also involve undergraduate and graduate students in the experiments to improve their understanding of science, forest biology and the environment.