PARENT SESSION
Oral Session # 66: Ecological Studies at Biosphere II.
Presiding: ML Martinez Vazquez
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Meeting Room 104.
A novel methodology for estimating mean residence times of ecosystem carbon pools.
Trueman, Rebecca*,1, Murthy, Ramesh2, Yakir, Dan3, Marshall, John4, Berry, Joseph5, Gonzalez-Meler, Miquel 1, 1 University of Illinois at Chicago, Chicago, IL, USA2 Columbia University Biosphere 2 Center, Oracle, AZ, USA3 Weizmann Institute of Science, Rehovot, Israel, Israel4 University of Idaho, Moscow, Idaho, USA5 Carnegie Institute of Washington, Washington, DC, USA
ABSTRACT- During the last century, anthropogenic fossil fuel emissions have been causing an increase in atmospheric carbon dioxide concentration that is altering the integrity and functioning of ecosystems worldwide. Since carbon exchange by vegetation far outweighs the anthropogenic carbon inputs any carbon cycling changes will determine whether an ecosystem is a source or a sink for atmospheric carbon. Mechanisms that control carbon storage and allocation in ecosystems have been elusive to scientists. Ecosystem carbon dynamics can be determined using natural abundance of stable isotopes. Stable isotopes provide the opportunity to look at ecosystem carbon processes by analyzing fractionation of the least abundant stable isotope 13C. Plant isotopic composition is more depleted in 13C than the atmosphere and the level of depletion is affected by climatic conditions. The isotopic signature of plant tissues is reflected in the respired carbon dioxide of plants, soils, and ecosystems. The release of carbon by respiration will be from a combination of ecosystem carbon pools of different mean residence time (MRT). In natural ecosystems it is difficult to not only measure carbon fluxes but also to estimate the MRT of carbon pools. In order to determine the MRT of carbon at an ecosystem scale a quantitative measurement technique has been needed. This methodology will be presented with data from Columbia University Biosphere 2.
Key words: stable isotopes, ecosystem carbon cycling, mean residence time of carbon, 13C