Aerobic and anaerobic microbial activities in the foreland of a receding glacier

The foreland soils of a receding glacier were investigated for both aerobic and anaerobic microbial activities. Estimation of microbial biomass via substrate induced respiration, and determination of dehydrogenase activity, dimethylsulfoxide reduction and ammonification were performed to describe soil microflora and its activity. These parameters distinctly increased along the chronosequence from the youngest to the oldest soil. Additionally, these properties showed remarkably higher values in the samples collected at the end of the growing season indicating distinct seasonal changes. The determination of methane emission by the three soils incubated at 10, 37 and 50 °C clearly pointed to higher methanogenic activities within the thermophilic temperature range. Our results also show that water saturation in order to simulate spring snow melt led to increased emissions of methane due to reduced oxygen availability. Methane release was generally low in the primary soil, slightly increased as soil formation proceeded and in all soils was distinctly higher at the end of the growing season. Potential methane consumption also increased along the foreland and during the year. Overall methanotrophic activity greatly exceeded methanogenic activity, and the net CH4 consumption distinctly increased along the chronosequence.