PARENT SESSION
Contributed Oral Session 49: Climate and Vegetation Dynamics
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 520 C, Level 5, Palais des congrès de Montréal
Carbon sequestrations in larch forest ecosystems.
Liang, Naishen*,1, Fujinuma, Yasumi1, Inoue, Gen1, 1 National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
ABSTRACT- We routinely measure net ecosystem exchange (NEE) with eddy covariance method at the larch forests in northern Japan, northeastern China and central Siberia. We partition component fluxes, i.e., using a 24-automated-chamber system for foliage photosynthesis/respiration, a 24-automated-chamber system for stem respiration, and a 24-automated-chamber system for the understory carbon budget (8 chambers for soil efflux, 8 chambers for heterotrophic respiration, and 8 chambers for photosynthesis/respiration of understory vegetation). For a 50-year-old larch forest in Japan, three year (2001-2003) averaged NEE was -186 and -500 g C m-2 yr-1, and Re was 1270 and 1095 g C m-2 yr-1 measured by the closed-path and open-path eddy system, respectively. With continuous measurements by the multichannel automated chamber approaches over the same period, soil efflux was averaged to 960 g C m-2 yr-1, heterotrophic respiration was about 547 g C m-2 yr-1 that accounted for about 57% of the soil efflux, net CO2 exchange of understory vegetation was about -39 g C m-2 yr-1, aboveground woody tissue respiration was bout 75 g C m-2 yr-1, and net photosynthesis and respiration of the canopy foliage was -1165 and 110 g C m-2 yr-1, respectively. During the non-growing season, NEE of larch forest measured by the eddy covariance method is the sum of aboveground woody tissue respiration and soil efflux. Aboveground woody tissue respiration contributed only 4.5% of NEE during the non-growing season, estimated by using volume-based woody tissue respiration and stem and branch biomass data. By the chamber approaches, averaged GPP, NPP (net primary production, the balance of GPP and autotrophic respiration), NEP (net ecosystem production, the balance of NPP and heterotrophic respiration) and Re was estimated to be about 1275, 677, 130 and 1145 g C m-2 yr-1, respectively. The contribution of canopy foliage respiration, aboveground woody tissue respiration, root respiration and heterotrophic respiration to GPP was estimated to be about 8.6%, 5.9%, 32.4% and 42.9%, respectively.
Key words: automated chamber, larch, photosynthesis, respiration