Terrestrial ecosystems exchange many chemical gases and particles with the atmosphere. These emissions alter atmospheric composition and affect climate through radiative forcing. Some flux exchanges (CH4, N2O) alter the concentration of long-lived greenhouse gases. Others alter short-lived gases that affect atmospheric chemistry and air quality. Chemistry-climate interactions from these short-lived climate forcers (NOx, biogenic volatile organic compounds, O3, secondary organic aerosols) are significant and comparable in magnitude to other climate forcings. Stable isotopes are useful to diagnose biogeochemical and hydrologic cycles. A research frontier is to link the biogeophysical and carbon cycle influences of terrestrial ecosystems with a full depiction of biogeochemical feedbacks mediated through atmospheric chemistry