Factors controlling CO2exchange in a middle latitude forest

Abstract

[1] The forest carbon uptake experiences a relatively steady state, in which both radiation use efficiency and Bowen ratio exhibit relatively small change in tendency during the middle growing season at a deciduous forest in New England. The net ecosystem exchange (NEE) during the steady state varies from 2.1 to 5.1 Mg C Ha−1 y−1, accounting for 58–83% of the annual amount over 1992–2004. The cloudiness, combined with the effect of antecedent accumulated precipitation from late January, plays a key role in controlling interannual fluctuations of the steady state GEE and NEE among other environmental factors, and determines the long-term trend of the site GEE and NEE. These two factors account for 74% of the interannual variability of forest carbon uptake for the steady state, and 58% for the entire growing season, respectively. This suggests that winter precipitation and summer clouds probably play a key role in regulating the carbon uptake, an important mechanism of the carbon cycle/climate interaction.