Using automated non-steady-state chamber systems for making continuous long-term measurements of soil CO2 efflux in forest ecosystems

► An efficient protocol to ensure good quality measurements of soil respiration with automated chambers has been lacking. ► We describe automation of the calculation and quality control by screening bad measurements. ► We compare the robustness of different procedures of calculating slope of the chamber headspace CO2 concentration. ► A procedure is described to estimate effective volume of chamber that is crucial for accurate estimation of soil CO2 efflux. ► We show that for lid closure periods <3% of the chamber-soil system time constant, using linear regression results in <2% underestimation of the efflux.