HR: 0800h
AN: B41B-0121    [Abstracts]
TI: Short-term increases in Summer Temperature and Rainfall do not Lead to Carbon Storage in the High Arctic
AU: * Steltzer, H
EM: steltzer@nrel.colostate.edu
AF: Colorado State University, Natural Resource Ecology Laboratory, Fort Collins, CO 80523-1499 United States
AU: Sullivan, P
EM: paddy@nrel.colostate.edu
AF: Colorado State University, Natural Resource Ecology Laboratory, Fort Collins, CO 80523-1499 United States
AU: Welker, J
EM: afjmw1@uaa.alaska.edu
AF: University of Alaska Anchorage, Biology Department Ecosystem and Molecular Biology Laboratory, Anchorage, AK 55910 United States
AB: From landscape to global scales climatic controls over primary production and ecosystem respiration are evident through the pattern of carbon accumulation in vegetation and soils. Few ecosystems, however, may be as constrained by climate as those within polar desert landscapes where ecosystem carbon accumulation is low, the average annual temperature is well below zero and precipitation is often less than 15 cm. To characterize how climate affects ecosystem carbon exchange in this cold, dry environment, we have established two experiments: 1) a factorial increase in summer temperature and rainfall and 2) a two-level warming experiment that includes ambient, and 2 and 4 degree C warming treatments. Within these experiments, we have measured net ecosystem carbon exchange (NEE), gross primary production (GPP), and ecosystem respiration (Re) during an extremely dry summer and a summer with average rainfall. Overall, we found that the ecosystem was a net source of carbon to the atmosphere in both years with an increase in carbon loss in the wetter year due to a greater increase in Re than GPP. An experimental increase in rainfall and higher yearly rainfall both led to greater GPP and Re. Increased temperatures only led to higher GPP in the year with more rainfall, and this response was non-linear. Warming increased respiration rates in both years. Although we can observe that carbon has accumulated in this landscape through time, it is not clear what climatic conditions lead to a net carbon gain in the High Arctic.
DE: 1615 Biogeochemical processes (4805)
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting