In this study we propose the hypothesis that ecosystem succession is accompanied by a decrease in the metabolic quotient qCO2 (respiration-to-biomass ratio) of the soil microflora. The qCO2 is calculated from basal respiration (CO2-C·h-1) per unit microbial biomass carbon (Cmier). The hypothesis was tested by studying two primary successions on recessional moraines of the Rotmoos Ferner (Austria) and the Athabasca Glacier (Canada). For both soil seres (0->200 years) it was shown that the qCO2 decreased with time, which corroborated the hypothesis. In addition, the short term development of the qCO2 was demonstrated with a revegetation trial. We observed a rise in qCO2 for the first two years after reclamation, followed by a subsequent decrease.