S.C. Wofsy J.W. Harden S.E. Trumbore P.M. Crill S.T. Gower T. Fries B.C. Daube S.-M. Fan D.J. Sutton A. Bazzaz J.W. Munger M. L. Goulden 1998 We used eddy covariance; gas-exchange chambers; radiocarbon analysis; wood, moss, and soil inventories; and laboratory incubations to measure the carbon balance of a 120-year-old black spruce forest in Manitoba, Canada. The site lost 0.3 ?? 0.5 metric ton of carbon per hectare per year (ton C ha-1 year-1) from 1994 to 1997, with a gain of 0.6 ?? 0.2 ton C ha-1 year-1 in moss and wood offset by a loss of 0.8 ?? 0.5 ton C ha-1 year-1 from the soil. The soil remained frozen most of the year, and the decomposition of organic matter in the soil increased 10-fold upon thawing. The stability of the soil carbon pool (~150 tons C ha-1) appears sensitive to the depth and duration of thaw, and climatic changes that promote thaw are likely to cause a net efflux of carbon dioxide from the site. application/pdf 10.1126/science.279.5348.214 en Sensitivity of boreal forest carbon balance to soil thaw article