Soil Co₂ Emission, Microbial Activity, C and N After Landsliding Disturbance in Permafrost Area of Siberia

In boreal forests developed on permafrost, landslide processes are widespread, occur in years of above average summer-autumn precipitation and can cover up to 20% of total area of slopes adjacent to rivers. Permafrost landslides will escalate with climate change. These processes are the most destructive natural disturbance events resulting in complete disappearance of initial ecosystems (vegetation cover and soil). We have studied sites of landslides of different ages (occurred at 2009, 2001 and 1972) along with Nizhnyaya (Lower) Tunguska River and Kochechum River to analyze postsliding ecosystem changes. Just after the event (as at 1-year-old site in 2010), we registered drop in soil respiration, 3 times decreasing of microbial respiration contribution, 4 times lower mineral soil C and N content at bare soil (melkozem) middle location of a site. Results show that regeneration of soil respiration and eco-physiological status of microbial communities in soil during post disturbance succession starts with vegetation re-establishment and organic soil layer accumulation. As long as ecosystems regenerate (as at 35-year-old site), accumulated litter contains similar to control C and N content as well as the main pool of microorganisms, though microbial biomass and soil C and N content of old landslide area does not reach the value of these parameters in control plots. Therefore, forested ecosystems in permafrost area disturbed after landsliding requires decades for final successful restoration.