Carbon Dioxide Evolution from the Floor of Three Minnesota Forests

Carbon dioxide evolution rates from forest floors, measured approximately weekly for 54 weeks in oak forest, marginal fen, and cedar swamp, were closely related to soil temperature and secondarily to moisture conditions. As a result, microclimatic and drainage characteristics of the three forests produced seasonal differences in carbon release. However, compensatory factors produced nearly equal cumulative annual totals of CO 2 evolution. Total CO 2 evolution was over three times higher than expected from an equivalent amount of carbon release from annual litter fall. Respiration by tree roots was suspected as the major contributor to this disparity although methodological problems related to flow rate are still open to question.