Development of permafrost-affected peatlands in the southern limit of the European Russian cryolithozone and their vulnerability to future warming

Permafrost degradation due to climate warming is currently observed in the northeastern part of European Russia. Peat plateaus underlain by permafrost cover only about 20% of the Russian European cryolithozone but contain almost 50% of soil organic carbon stocks (SOC), which are considered to be vulnerable to microbial mineralization after permafrost thaw. The current study was performed at three key sites of peat plateaus located along the southern permafrost limit. SOC decomposition was studied by aerobic and anaerobic incubation experiments, conducted at 4 °C over a period of 1301 days. The CO2 production was measured in peat samples at three key sites from the active layer (AL), transitional layer (TL), permafrost layer (PL), and at one site from the deep permafrost layer (DPL), which is in contact with mineral soil at 3.7 m depth. During the experiment, the initial СО2 respiration rates significantly differed in the samples AL, TL and PL in all key sites. However, at each site in the majority of samples the CO2 respiration rates were 2–5 times aerobically higher than anaerobically. In anaerobic conditions, in all sites, the СО2 respiration rate in PL was the lowest, higher in TL and the highest in AL in all 3 sites. Projections of CO2 aerobically production for 80 years represent 1.44 ± 0.11, 6.31 ± 0.47, 30.64 ± 17.98% of initial permafrost carbon from the samples of Inta 1, Inta 11 and Kolva respectively. But under anaerobical conditions estimates are close and indicate insignificant amounts 0.30…1.90% of carbon release over a period of 80 years. We suggest that even under ideal conditions of the incubation experiment, without considering ecological inertia under natural conditions, while also permafrost temperature is close to zero, greenhouse gas release from initial SOC is significantly less than estimated.