NET EXCHANGE OF CO2 IN A MIDLATITUDE FOREST

The eddy correlation method was used to measure the net ecosystem exch ange of carbon dioxide continuously from April 1990 to December 1991 i n a deciduous forest in central Massachusetts. The annual net uptake w as 3.7 +/- 0.7 metric tons of carbon per hectare per year. Ecosystem r espiration, calculated from the relation between nighttime exchange an d soil temperature, was 7.4 metric tons of carbon per hectare per year , implying gross ecosystem production of 11.1 metric tons of carbon pe r hectare per year. The observed rate of accumulation of carbon reflec ts recovery from agricultural development in the 1800s. Carbon uptake rates were notably larger than those assumed for temperate forests in global carbon studies. Carbon storage in temperate forests can play an important role in determining future concentrations of atmospheric ca rbon dioxide.