HR: 1340h
AN: C13B-0285    [Abstracts]
TI: Peatland Carbon Accumulation in West Siberia Over the Last 2,000 Years
AU: * Beilman, D W
EM: dbeilman@ucla.edu
AF: Department of Geography, University of California Los Angeles, 1255 Bunche Hall Box 951524 L.A, CA 90095-1524 , Los Angeles, CA 90095 United States
AU: MacDonald, G M
EM: macdonal@geog.ucla.edu
AF: Department of Geography, University of California Los Angeles, 1255 Bunche Hall Box 951524 L.A, CA 90095-1524 , Los Angeles, CA 90095 United States
AU: Smith, L C
EM: lsmith@geog.ucla.edu
AF: Department of Geography, University of California Los Angeles, 1255 Bunche Hall Box 951524 L.A, CA 90095-1524 , Los Angeles, CA 90095 United States
AU: Kremenetski, K V
EM: costya@geog.ucla.edu
AF: Department of Geography, University of California Los Angeles, 1255 Bunche Hall Box 951524 L.A, CA 90095-1524 , Los Angeles, CA 90095 United States
AU: Kremenetski, K V
EM: costya@geog.ucla.edu
AF: Institute of Geography, Rusian Academy of Sciences 29 Staromonetny Lane, Moscow, 109017 Russian Federation
AU: Velichko, A A
EM: paleo@online.ru
AF: Institute of Geography, Rusian Academy of Sciences 29 Staromonetny Lane, Moscow, 109017 Russian Federation
AU: Reimer, P J
EM: pjreimer@llnl.gov
AF: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Lab, P.O. Box 808, L-397 Livermore, CA, Livermore, CA 94450 United States
AB: The peatlands of the West Siberia Lowland (WSL) are of global significance owing to the massive carbon (C) stocks they hold (70 Pg C) and their location at the focus of both observed and predicted Arctic warming. Greater understanding of the potential warm-climate sensitivity of northern peatlands using paleoecological approaches is limited by past large shifts in hydrology and plant communities, as well as large temperature and moisture changes over the course of the Holocene (today's peatlands and climate are different than their mid-early Holocene counterparts). Therefore, we investigated the last 2,000 years to identify baseline peat C accumulation rates and behavior more relevant to the modern WSL. We identified the 2,000-year-old level in 21 peat cores from across the WSL (57-68\deg N) via successive $^{14}$C-AMS radiocarbon age determinations of specific plant fragments. Peat organic C content at 2-10 cm resolution in each core was calculated from ash-free bulk density and a mean C content of peat organic matter (52%). Over the last 2,000 years, 11 northern WSL cores (north of 63\deg N) accumulated 12-58 cm peat (7-33 kg C m$^{-2}$, or 5-32% total C per core) and 10 southern WSL cores (south of 63\deg N) accumulated 63-258 cm peat (23-56 kg C m$^{-2}$, or 14-70% total C per core). Mean net C accumulation, incorporating slow decomposition losses (0.00002 yr$^{-1}$), in southern WSL cores was about twice that of northern WSL. We calculated the apparent rate of Holocene C accumulation for each core using 21 $^{14}$C-AMS radiocarbon ages of basal bulk peat. Long-term Holocene apparent rates show no relationship with apparent rates over the last 2,000 years. More than half the cores show slower recent rates, including some southern cores. Overall, these results show that net atmospheric C sequestration in WSL over the last two millennia has been spatially disproportionate: sequestration has slowed substantially from mid-early Holocene rates in the north, and shows significantly stronger C sink with decreasing latitude in the south. Our findings suggest that concentrating on C accumulation trends over recent millennia is the best paleoecological approach to identify the spatial nature of modern long-term terrestrial C sinks.
DE: 9315 Arctic region
DE: 1890 Wetlands
DE: 1615 Biogeochemical processes (4805)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting