Fig. 2
a Mean annual cycle of biological CO2 fluxes (net ecosystem exchange; NEE) for a forest site (dark green), a corn site (yellow) and a soybean site (light green). The forest fluxes are the 5-year mean measured at the Morgan Monroe State Forest [35] and the corn and soybean fluxes are the 3-year mean measured in Bondville, Illinois [36]. b Domain-averaged 31-day median (fossil fuel (Hestia) emissions as a function of time of year for 2014