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To characterize soil CO₂ under different forest types and several years after a clear‐cut harvest, soil CO₂ evolution and soil air CO₂ concentrations were measured at three sites in Maine: the Howland Integrated Forest Study (HIFS) site, the Bear Brook Watershed in Maine (BBWM) site, and the Letter E township (Letter E) site. Soil CO₂ evolution means ranged from 0.19 to 0.32 g m⁻² h⁻¹ among sites, whereas soil air CO₂ concentration means ranged from 1023 µL L⁻¹ for the O horizon to 3296 µL L⁻¹ for the C horizon for the 1990 growing season. Soil CO₂ evolution and soil air CO₂ concentrations were similar under deciduous and coniferous forests and 4 to 6 yr after harvest. Limited multiple‐year data suggest that significant annual variations in temporal patterns of these properties exist as a function of short‐term climatic factors. These data suggest that soil CO₂ evolution and soil air CO₂ concentrations may …