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CO2 Exchange over the Alaskan Arctic Tundra: Meteorological Assessment by an Aerodynamic Method

Patrick I. Coyne and John J. Kelley
Journal of Applied Ecology
Vol. 12, No. 2 (Aug., 1975), pp. 587-611
DOI: 10.2307/2402176
Stable URL: http://www.jstor.org/stable/2402176
Page Count: 26
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CO2 Exchange over the Alaskan Arctic Tundra: Meteorological Assessment by an Aerodynamic Method
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Abstract

Seasonal and diurnal courses of atmospheric CO2 flux were calculated above a wet meadow arctic tundra near Barrow, Alaska during the 1971 growing season using profile data from an aerodynamic method. A curvilinear regression equation, expressing CO2 flux as a function of irradiance, soil surface temperature and chlorophyll content of the standing crop, was fitted by a least squares technique. The purpose of the regression analysis was to allow prediction of missing data so that net seasonal CO2 fluxes could be calculated. The intercept portion of the regression equation represented CO2 flux at zero irradiance and was used to estimate CO2 flux from ecosystem respiration. The sum of atmospheric and respiration CO2 fluxes was an estimate of gross CO2 uptake by the tundra community. Values obtained for seasonal CO2 flux from the atmosphere and respiration were 146 g m-2 and 626 g m-2 respectively for a gross CO2 incorporation estimate of 772 g m-2. Our estimate of gross uptake of CO2 compared favourably with independent methods assessing primary production at the study site. The data suggest that plant respiration and microbial decomposition contributed the majority of the CO2 being fixed by photosynthesis. Since the thaw period is short, much of the annual decomposition proceeds concurrently with annual productivity. In addition, the relative high belowground to aboveground ratio of living biomass amplifies the rate of CO2 evolution form the soil. The net flux of CO2 from the atmosphere (146 g m-2) is an estimate of the CO2 which must be released by respiration activity before and/or after the growing season in a steady-state ecosystem. Even though the photoperiod is 24 h long at the Barrow latitude during much of the season, a portion of all days exhibited net CO2 flux to the atmosphere. This indicated that the CO2 from ecosystem respiration often exceeded the CO2 used by photosynthesis although individual plants might show positive net photosynthesis even at solar midnight.

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