HR: 1340h
AN: B33E-1087    [Abstracts]
TI: Climate, Tree Rings, and CO2 fluxes in a Canadian Boreal Forest
AU: * Rocha, A V
EM: arocha@uci.edu
AF: Department of Earth Systems Science, 3200 Croul Hall, Irvine, Ca 92612
AU: Goulden, M L
EM: mgoulden@uci.edu
AF: Department of Earth Systems Science, 3200 Croul Hall, Irvine, Ca 92612
AU: McMillan, A
EM: mcmillaa@uci.edu
AF: Department of Earth Systems Science, 3200 Croul Hall, Irvine, Ca 92612
AU: Winston, G
EM: gwinston@uci.edu
AF: Department of Earth Systems Science, 3200 Croul Hall, Irvine, Ca 92612
AU: Read, E
B33E-1087 AF: Department of Earth Systems Science, 3200 Croul Hall, Irvine, Ca 92612
AU: Dunn, A L
EM: adunn@deas.harvard.edu
AF: Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
AU: Wofsy, S C
EM: wofsy@fas.harvard.edu
AF: Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
AB: The linkages between forest physiology and growth are poorly understood. While recent work has shown that increased photosynthesis does not always translate into increased growth, studies have yet to clearly demonstrate the uncoupling between the photosynthesis and growth in forests. We used a 10 year record of eddy covariance data (1995-2004), an empirical model of Gross Ecosystem Productivity (GEP), and a 36 year ring width chronology from an Old Black Spruce ( Picea mariana [Mill.]) (NOBS) stand in Northern Manitoba to determine the relationship between canopy physiology and ring width. Over the time period of eddy covariance measurement ring width and NEP increased, while annual and average growing season nighttime respiration decreased. The empirical model of GEP, parameterized by 10 years of eddy covariance data, captured the interannual variability in measured GEP and was used to extend the record of GEP back 36 years using historical data from a nearby weather station. Our results demonstrate that GEP and ring width are uncoupled and that growth and GEP appear to respond to climatic forcing at different temporal scales. Fluctuations in GEP were attributed to yearly variations in temperature and incoming solar radiation, whereas, ring width fluctuations varied little from year to year with an apparent periodicity of ~7 years. Fluctuations in ring width at NOBS were similar to those observed at a nearby 70 year old black spruce stand, implying that fluctuations in ring width are controlled by an external factor such as climate. However, we were unable to link ring width with annually integrated climatic variables. We suspect that the storage of carbohydrates in trees integrates carbon uptake over multiple years and buffers wood production from year to year variation in GEP.
DE: 0428 Carbon cycling (4806)
DE: 0434 Data sets
DE: 0476 Plant ecology (1851)
SC: Biogeosciences [B]
MN: Fall Meeting 2005