HR: 11:20h
AN: B42B-04    [Abstracts]
TI: Interannual variability in CO2 exchange along a boreal chronosequence
AU: * McMillan, A M
EM: mcmillaa@uci.edu
AF: University of California, Irvine, Department of Earth System Science 1222 Croul Hall University of California, Irvine, Irvine, CA 92697-3100 United States
AU: Rocha, A V
B42B-04 AF: University of California, Irvine, Department of Earth System Science 1222 Croul Hall University of California, Irvine, Irvine, CA 92697-3100 United States
AU: Winston, G C
B42B-04 AF: University of California, Irvine, Department of Earth System Science 1222 Croul Hall University of California, Irvine, Irvine, CA 92697-3100 United States
AU: Goulden, M L
EM: mgoulden@uci.edu
AF: University of California, Irvine, Department of Earth System Science 1222 Croul Hall University of California, Irvine, Irvine, CA 92697-3100 United States
AB: Natural fires in the boreal region create a mosaic of different-aged forests with different capacities to store or release carbon. Interannual variations in climate are expected to have different effects on forest carbon exchange depending on time since burn. We investigated how gross photosynthesis, ecosystem respiration and net ecosystem exchange responded to climate variability among different aged stands. Net carbon exchange was measured at seven different aged forests (ranging from 155 to 2 years since burn) over the last 5 growing seasons by eddy covariance. Pronounced year to year variability in the growing season length occurred over these years and provided the opportunity to observe how differences in the timing of the growing season contributed to the net exchange of carbon each year. Earlier springs lead to greater annual photosynthetic uptake in older stands but the younger stands were less able to take advantage of the early spring. Younger forests were also more severely affected by summer conditions that followed an early spring than older forests. For both older and younger forests, interannual variability NEP was determined more by changes in photosynthetic gains than changes in respiratory losses. Characterizing the response of a boreal chronosequence to interannual weather variations may help in determining the nature of feedbacks that will occur between terrestrial vegetation and climate under the temperature increases that are projected for the boreal region.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0428 Carbon cycling (4806)
SC: Biogeosciences [B]
MN: Fall Meeting 2005