Carbon gas exchange at a southern Rocky Mountain wetland, 1996–1998

Carbon dioxide (CO2) and methane (CH4) exchange between the atmosphere and a subalpine wetland located in Rocky Mountain National Park, Colorado, at 3200 m elevation were measured during 1996–1998. Respiration, net CO2flux, and CH4flux were measured using the closed chamber method during snow‐free periods and using gas diffusion calculations during snow‐covered periods. The ranges of measured flux were 1.2‐526 mmol CO2m−2d−1(respiration), −1056−100 mmol CO2m−2d−1(net CO2exchange), and 0.1–36.8 mmol CH4m−2d−1(a positive value represents efflux to the atmosphere). Respiration and CH4emission were significantly correlated with 5 cm soil temperature. Annual respiration and CH4emission were modeled by applying the flux‐temperature relationships to a continuous soil temperature record during 1996–1998. Gross photosynthesis was modeled using a hyperbolic equation relating gross photosynthesis, photon flux density, and soil temperature. Modeled annual flux estimates indicate that the wetland was a net source of carbon gas to the atmosphere each of the three years: 8.9 mol C m−2yr−1in 1996, 9.5 mol C m−2yr−1in 1997, and 9.6 mol C m−2yr−1in 1998. This contrasts with the long‐term carbon accumulation of ∼0.7 mol m−2yr−1determined from14C analyses of a peat core collected from the wetland.