The biological properties of alas soils influenced by pasture degradation at a load of five to six livestock units per hectare have been studied. It has been shown that manure in the amount of about 2 t dry substance/ha per year under cryoarid conditions allows for the studied characteristics to be maintained in a 0–20-cm soil layer at the level of background values for alas soil. The stability of the microbial community established in degraded alas soils has been estimated.

The aim of the study. To investigate some microbiological properties of the catenal series of soils in the Kuidusun depression of the Oymyakon Highlands. Location and time of the study. The study area is located in the vicinity of the Tomtor village (N63°15'41.94''; E143°10'26.91'') of the Oymyakonsky district of the Republic of Sakha (Yakutia, Russia). Soil samples were collected in the fall of 2011 at the main positions of the catena. The length of the catena is 38 km, the altitude a.s.l. is 727–821m. Soils are classified as Cambic Cryosols (fragic, мurshic), (forest); Skeletic Cryosols (aridic), (steppe meadow), Cambic Cryosols (fluvic), (typical meadow); Folic Cryosols (swampy meadow). Methods. The content of labile soil organic matter (LOC) was determined photocalorimetrically in soil extracts with phosphate buffer (1/15 M, pH 6,8). The number of colony-forming units (CFU) was determined using standard MPA, KAA, and Czapek media. The functional spectrum of the soil microbiota was assessed using the community level physiological profile (CLPP) method. All properties were studied in 10 cm thick layers to a depth of 40 cm. Soil urease activity was assessed by ammonium production from urea. Results. At the time of sampling moisture content of soil samples down the catena increased from 5 to 20%, whereas the LOC content increased from 2 to 6 g C /kg. In the 0–10 cm layer, the greatest accumulation of LOC was observed in the soil under a typical meadow. The highest number of CFU (150 million/g soil) in a dilute MPA medium was also found there. An increase in the proportion of CFU in the dormant state was revealed in the soil series from the lower position of the catena to the upper one. In the same series, an increase in the oligotrophic index of the community was noted. The highest metabolic activity was observed in the soil under a swampy meadow, whereas the lowest was shown by the soil under a forest. The enrichment of soil organic matter with microbiota cells increased in the series of soils f in the following order: a swampy meadow – a typical meadow – a steppe meadow, whereas the specific activity of the microbiota decreased. Urease activity of the soil was detected mainly in the 0–10 cm layer; in the underlying layers the activity was more than 500 times lower. Conclusions. The biological properties of the studied soils corresponded to the known patterns established for the catenal series of soils in other soil and climatic conditions. The peculiarity of the studied soils was related to the extremely sharp differentiation of the microbiological profile. The absolute predominance of actinomycetes CFU in the soil under the steppe meadow was the major characteristic feature of the culturable part of the soil microbial community.

The Arctic has experienced numerous fires in last year, and from June to August 2020, satellite data showed record carbon dioxide emissions from forest fires. Peatland in the Arctic contains large amounts of organic carbon, and their release into the atmosphere can create positive feedbacks for further increase of air temperature. In addition, forest fires burn the surface vegetation layer that has been acting as a heat insulator, which will accelerate the thawing of permafrost on scales of years to decades. Although the thaw depth can recover together with the recovery of surface vegetation, the massive segregated ice is not recoverable once it melted. Our study area is around the Batagay, Sakha Republic, Eastern Siberia. In June 2020, Verkhoyansk, located about 55 km west of Batagay, recorded the highest daily maximum temperature of 38.0 degrees Celcius. The Sentinel-2 optical satellite images showed a number of forest fires in 2019-20. We detected the surface deformation signals at each fire site with the remote-sensing method called InSAR (Interferometric Synthetic Aperture Radar). Also, we conducted a field observation in September 2019 for validations: 1) installed a soil thermometer and soil moisture meter; 2) established a reference point for leveling and first survey; 3) measured the thawing depth with a frost probe. For seasonal ground deformations immediately after the fire, we mainly analyzed Sentinel-1 images. Sentinel-1 is the ESA's C-band SAR satellite, which has a short imaging interval of 12 days. As the short wavelength, vegetation changes lost coherence, and some pairs failed to detect ground deformation signals immediately after the fire. However, after the end of September, we detected displacements toward the satellite line-of-sight direction at all the fire sites. It indicates uplift signals due presumably to frost heave at the fire scar. For long-term deformations over one year, we used ALOS2 imaged derived by JAXA's L band SAR satellite. In the previous studies in Alaska, the ground deformation signal immediately after a fire could not be detected due to the coherence loss in the pairs derived from pre-fire and post-fire SAR images. Indeed, we could not detect deformation signals at the fire scars from the June pairs derived before and after the fire. However, the January pairs and March pairs, both of which were acquired before and after the fire, showed relatively high coherence even in the fire scar and indicated clear subsidence signals by as much as 15 cm. We interpret that, because the studied Verkhoyansk Basin is very dry and has little snow cover, the microwaves could penetrate the snow layer, which allowed us to detect deformation signals even in winter. Yanagiya and Furuya (2020) validated the consistency of the winter uplift signal for the 2014 fire site. We also analyzed the SM1 high spatial resolution mode (3 m) ALOS2 InSAR to investigate the specific ground deformation at each fire site.

The degradation of modern and ancient permafrost-affected soils and organic-rich sediments and the release of relict soil organic matter from the frozen state are critical for understanding the global carbon cycle in a changing climate. The molecular structure of humic acids isolated from modern Cryosols and paleosoils from the Ice Complex deposits in the Batagay megaslump area was investigated. The elemental composition analysis was performed using a CHN analyzer, and molecular composition analysis was determined by CP/MAS ¹³C-NMR spectroscopy. Analysis of the molecular structure of humic acids showed that MIS 5e paleosoils are characterized by a relatively high content of aliphatic structural fragments (C,H-AL—29–36%) and a low content of aromatic structural fragments (AR/AL—0.49–0.43), which reveals low humification rates in this time period. The composition of humic acids from MIS 7 paleosoils shows a relatively high content of aromatic structural fragments compared to modern soils (AR/AL—0.47) and MIS 5e deposits (AR/AL—0.67–0.54), indicating a longer humification process in heterogenic conditions (warm and cold periods). The results indicate that the molecular structure of humic acids is a dynamic parameter of the environment that reflects the local conditions of pedogenesis and organic matter formation. Permafrost thawing leads to the release of organic matter (including matter that is relatively weakly resistant to biodegradation where aliphatic structural fragments dominate the composition of humic acids) that may strengthen the emission of climate-active gases into the atmosphere and boost climate change.