HR: 1330h
AN: B22A-0790    [PDF]
TI: Carbon Exchange Along a Vegetation Gradient from Arctic Tundra to Boreal Forest
AU: * Thompson, C C
EM: ftcdc@uaf.edu
AF: Dept. Biology and Wildlife, 211 Irving I University of Alaska, Fairbanks, Fairbanks, AK 99775 United States
AU: Beringer, J
EM: jason.beringer@arts.monash.edu.au
AF: School of Geography and Environmental Science, PO Box 11A Monash University, Clayton, 3800 Australia
AU: McGuire, A
EM: ffadm@uaf.edu
AF: U.S. Geological Survey Alaska Cooperative Fish and Wildlife Research Unit, University of Alaska, Fairbanks, Fairbanks, AK 99775
AU: Chapin, F S
EM: terry.chapin@uaf.edu
AF: Institute of Arctic Biology, 311 Irving I University of Alaska, Fairbanks, Fairbanks, AK 99775
AB: Understanding environmental change in arctic and subarctic regions in response to altered climate forcing is of primary interest because of the role these ecosystems play in feedbacks to climate and carbon storage. Shifts in the balance between net carbon gains and losses in high latitude ecosystems could result as the vegetation and soil layers respond differently to changing environmental conditions such as changing moisture and temperature regimes and a lengthening growing season. Vegetation responses such as shrub expansion and northward movement of treeline would be expected to alter carbon cycling in high latitude ecosystems, however, the effect on net carbon storage due to changes in the distribution of plant functional types is incompletely understood. We selected moist low shrub tundra, tall shrub tundra and forest tundra sites near treeline in northwestern Alaska to represent the major structural transitions that would be expected in arctic and subarctic ecosystems in response to warming. In these sites, we measured above ground net primary production (NPPa) and summer net ecosystem exchange (NEE) using tower-based micro-meteorological techniques. We constructed carbon budgets, based on a combination of these direct measurements, literature based estimates and model simulations. All three sites were net sinks for carbon, with the shrub site having nearly twice the sink strength of the tundra and forest tundra site. We compare micro-meteorological and biometric approaches to estimating carbon exchange and we discuss sources of uncertainty in our estimation techniques.
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2003 Fall Meeting