We developed a new ecophysiology module to mechanistically simulate land−atmosphere exchange of important gas species in GEOS-Chem v12.2.0. We adopted the formulations from the Joint UK Land Environmental Simulator (JULES) to couple photosynthesis rate, bulk stomatal conductance and isoprene emission rate dynamically. The implementation not only allows dry deposition and biogenic emissions to be coupled with plant ecophysiological processes such as photosynthesis, but also enables plant and crop productivity and functions to respond dynamically to atmospheric chemical changes.