The amounts and exact locations of atmospheric carbon (C) sequestered in forests vary greatly among estimates. A recent inverse modeling study, estimated that temperate North American forests sequester more C(1.7Pg y ^-1) than is emitted from fossil fuel consumption in North America (>15⁰N). Coupling eddy covariance C exchange measurements and land cover data, we roughly estimate the C sink in forests of conterminous United States (USc) as only ca. 50%(0.78 Pg y^-1 ) of North American emissions. Owing to intensive management and long growing season, forests in Southeast Usc appear as dominant C sink, accounting for 50% the C sequestered in North America. However, given the intensive forest management practiced in the southeast US, these forests may merely act as a strong C pump that affects seasonal biosphere-atmosphere-atmosphere C exchange, but contributes little to long-term C sequestration, Consequently, C sequestration in North American forests may be as low as 25% of emissions.