Atmosphere‐biosphere exchange of carbon dioxide in boreal forests

An ecophysiological model of photosynthesis and respiration by forest ecosystems was used to examine CO 2 fluxes in 23 mature boreal forests near Fairbanks, Alaska. Simulated soil respiration, photosynthesis, decomposition, and moss and tree productivity were consistent with observed data. Monthly ecosystem CO 2 flux and net photosynthesis, averaged over the 23 sites, were correlated with atmospheric CO 2 concentrations and δ 13 ratios, respectively, at Barrow, Alaska, suggesting the boreal forests of Alaska play an active role in the seasonal dynamics of atmospheric CO 2 at Barrow. Only one of the 23 stands was a source of CO 2 , and the 23 stands absorbed (mean ± SE) 1173±211 g CO 2 m −2 yr −1 . Observed productivity in these forests spans the range of productivity in the circumpolar boreal forest, suggesting the simulated CO 2 fluxes are representative of the circumpolar boreal forest. If so, metabolic activity in the circumpolar boreal forest results in a significant annual uptake of CO 2 .