JP2.2
Spatial and Temporal Variability of Carbon Flux on the North Slope of Alaska: A Study of the Barrow-Atqasuk-Ivotuk Region
Walter C. Oechel, San Diego State University, San Diego, CA; and H. Kwon, R. Zulueta, J. Verfaillie, G. Kinoshita, J. Kimball, F. A. Heinsch, and S. Running
The Arctic represents a model biome to study the effects of climate change on ecosystem function. This is due to the sensitivity of Arctic ecosystems to global warming and climate change and the resultant effects on the magnitude and direction of net ecosystem CO2 exchange (NEE). Despite a seemingly homogeneous landscape, Arctic tundra presents complex heterogeneities that are apparent from in situ measurements. A complete understanding of carbon exchange dynamics on the North Slope requires a scaling approach that will measure fluxes at a range of decimeters to thousands of kilometers. This study was conducted to address the temporal and the spatial variability over the Alaskan Arctic Tundra. We evaluate the spatial and temporal carbon flux in the North Slope region through the use of eddy covariance towers, chamber-based measurements, flux aircraft, satellite imagery, and ecosystem modeling. The eddy covariance method was used to measure the NEE of wet coastal sedge tundra (71° 21' 00.00" N: 156° 37' 18.53" W) and moist tussock tundra (70° 28' 10.6" N: 157° 24' 32.2" W) ecosystems during the growing season (June ~ August) from 1999 to 2003 and old tussock tundra (68° 29' N: 155° 44' W) ecosystem during the growing season in 2003. The cumulative NEE of wet coastal sedge tundra showed a strong sequestration of carbon compared to that of moist tussock tundra and old tussock tundra. The seasonal integrated carbon uptake from the atmosphere was 50.0 gC m-2 in the wet coastal sedge tundra, 13.0 gC m-2 in the moist tussock tundra, and 37.0 gC m-2 in the old tussock tundra. The difference in amplitude of the seasonal carbon exchange between the three sites is caused by differences in the contribution of plant productivity and ecosystem respiration to carbon exchange under different climatic conditions. Chamber based measurements have shown differential responses to altered moisture and temperature, in a full factorial design, which is expected to be affected by the microtopographic position of the vegetation, the composition, and the site moisture level. Aircraft measurements compare well with tower measurements to date and maintain a strong correlation with satellite NDVI and surface type datasets. Further, the Biome-BGC ecosystem model results show a positive relationship with satellite data.
Joint Poster Session 2, Formal Poster Viewing - High Latitude Climate Variability and Change (Joint with the Eight Conference on Polar Meteorology and the 16th symposium on Global Change & Climate Variations)
Thursday, 13 January 2005, 9:45 AM-11:00 AM
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