The soils of boreal landscapes are continuously shaped by fire and keep the memory of this essential ecosystem process. A part of the pyrogenic record is stored in the sequestered charred biomass, including wood charcoal, which is a long-living carrier of information about past vegetation and fire regimes. Raman spectroscopy of charcoal is still a developing tool used to decipher the chemical signature of the original heat impact and further diagenesis of charred wood in a depositional setting. Here, we examine the molecular structure of charcoal sequestered in Podzols and Arenosols of the European north during fires of the recent past and the Holocene paleofires. We combine Raman spectroscopy of charcoal with the extraction of a time factor estimate from the historical records of fire and radiocarbon dating of burned biomass. With these data, we further explore if changes in the molecular structure of charcoal are time-referenced. Over 950 Raman spectra were collected from macrocharcoal particles produced during 10 historically documented fires (2-160 years since fire) and those sequestered in 31 pyrogenic horizons and morphones of paleosols during the last similar to 9700 cal BP. Calculated Raman spectral metrics included D and G bands positions, their separation, and the four ratios: H-D/H-G, H-V/H-G, H-1710/H-G, photoluminescence slope/H-G. Obtained multivariate dataset suggests a continuum of diverse molecular signatures in charcoal associated with production conditions and ageing in soil. With the use of principal component analysis and hierarchical clustering, we assess the blocks of charcoal memory mostly associated with charring conditions and those attributed to such diagenetic processes as oxidative weathering and saturation by C-H-dominated organic matter. Pronounced changes in the molecular structure of charcoal happened rapidly and depended on soil conditions. While many charcoals became significantly altered within years and decades, some fragments may have better preserved the chemical signature of original charring conditions, even if produced in paleofires of the Early- and Mid-Holocene.

The paper presents the results of a study of samples from the “pink horizon” in sediments of the Onega Ice Lake. A large amount of iron in this horizon is shown, their shapes and sizes are determined. The presence of microbial mats and biofilms in this layer was revealed, and a conclusion was made about the rate of accumulation of varyed clays.

Microbial biomass, diversity of culturable bacteria and micromycetes, and the number of functional nitrogen cycle genes in the supraglacial systems of the Aldegonda and Bertil glaciers have been studied. The biomass of microorganisms varies from 2.54 to 722 µg/g substrate. It is shown for the first time that the major part (78.7–99.8

Microbial biomass, diversity of cultivated bacteria and micromycetes, as well as the number of functional nitrogen cycle genes in the supraglacial systems of the Aldegonde and Bertel glaciers were studied. Biomass of microorganisms varied from 2.54 to 722 µg/g of substrate. It has been shown for the first time that the majority (78.7–99.8%) of the microbial biomass of supraglacial objects is represented by fungi rather than prokaryotes. Main part (from 70 to 90%) of the fungal biomass was mycelium, the length of which varied from 6.70 to 537.51 m/g of substrate. The number of prokaryotes varied from 2.4 × 108 to 1.95 × 109 cells/g of substrate. The length of actinomycete mycelium varied from 2.6 to 62.61 m/g of substrate. The abundance of cultivated bacteria and actinomycetes varied from 3.3 × 104 to 1.2 × 106 CFU/g of substrate, and that of micromycetes varied from 2.2 × 101 to 1.7 × 104 CFU/g of substrate. Bacteria of the genera Arthrobacter, Bacillus, Rhodococcus, and Streptomyces, as well as micromycetes of the genera Antarctomyces, Cadophora, Hyphozyma, Teberdinia and Thelebolus dominated. Micromycetes Antarctomyces psychrotrophicus, Hyphozyma variabilis and Teberdinia hygrophila were found in Svalbard for the first time. The number of amoA genes in ammonium-oxidizing bacteria varied from 5.33×106 to 4.86 × 109; nitrogen fixation genes nifH, from 9.89 × 107 to 9.81 × 1010; nirK denitrification genes, from 4.82 × 107 to 3.34 × 1010 gene copies/g of substrate. The results obtained indirectly indicate the leading role of fungi in the microbiome of the supraglacial objects of Svalbard and the significant contribution of prokaryotes to the emission of greenhouse gases from them.

For the first time, a comprehensive assessment of the biological activity of the supraglacial systems of the IGAN Glacier—the largest glacier of the Polar Urals—was carried out. The stocks and structure of microbial biomass were estimated using luminescent microscopy and substrate-induced respiration methods; basal respiration, the intensity of methanogenesis and nitrogen fixation, the number of copies of ribosomal genes of microorganisms (bacteria, archaea, and fungi), and the numbers (CFU/g soil) of cultivated micromycetes, saprotrophic bacteria, and actinomycetes were also studied. The highest biological activity was found in the supraglacial zone, and the lowest—along its periphery and in the near periglacial zone. In all zones of the glacier, Geomyces pannorum, G. vinaceus, and Teberdinia hygrophila dominated among micromycetes, and representatives of the Arthrobacter and Bacillus genera dominated among bacteria. The microbiome structure of supraglacial bodies depended on their location on the glacier and differed significantly at the periphery and in the center of the supraglacial zone, as well as in comparison with soils and sediments in the adjacent periglacial landscape. The material released from the glacier body with a high content of organic matter affects the biological activity of supraglacial microbial communities.

— In the 21st century, glaciers are perceived as a distinct biome that has taken on special significance in today’s world of retreating ice. In this paper, we review the results of recent studies of organomineral formations on glaciers, their diversity, genesis, functioning, and the role in the biosphere. The question is raised about the possibility of involving supraglacial organomineral formations in the range of objects of soil science. We review the supraglacial zone as an area of soils and soil-like bodies, the biogeochemical processes in which affect the glacial biome and the surrounding landscapes. Interpretation of supraglacial organomineral formations from a pedological point of view allows us to identify several typical soil processes: accumulation and stabilization of organic matter (OM), its heterotrophic transformation, formation of dark-colored humified OM, accumulation of residual solid-phase products of functioning in situ, fine earth aggregation, and biochemical weathering. Among supraglacial formations, we distinguish pre-soils and soil-like bodies in ice and snow, metastable soil-like bodies on cryoconite, and soils with microprofiles under moss communities on ice, as well as relatively stable soils with macroprofiles on silicate gravelly to fine-earth deposits underlain by moving glacier and dead glacier ice. Labile dissolved OM accumulated and transformed in supraglacial soils and soil-like bodies has a significant impact on the periglacial zone, leading to the reservoir and priming effects. The studies of supraglacial organomineral systems are of fundamental importance for understanding the evolution of ecosystems on Earth, as well as for modeling supraglacial formations of extraterrestrial bodies with a vast cryosphere. Supraglacial soil formation is also a model object for studying common soils under conditions of a continuous external input of organic and mineral components, the contribution of which beyond the glaciers is no less significant, but is masked by the polymineral substrate of soils and parent rocks themselves.

Fire relentlessly modifies the belowground pool of pyrogenic carbon (PyC) in boreal ecosystems. However, only a few soils offer a consistent record of PyC accumulation. Here, we report on the Holocene-scale record of biomass burning and PyC sequestration in the paleosoils of dry topographic hollows at the Keiva ice-marginal landform. We combine soil stratigraphy, radiocarbon dating, and chemical analyses to explore the chronology and properties of macrocharcoal that accumulated in soils for millennia. The most ancient pyrogenic horizons refer to 10,700-10,200 cal BP. They contain charred remnants of well-pronounced root systems as a part of the paleosoil, suggesting enough biomass for intensive burning and significant PyC sink into soils soon after deglaciation. The major phase of woody biomass burning occurred during 7000-5000 cal BP and resulted in the abundant deposition of charcoal in topographic hollows. Soil macrocharcoal maintained a remarkably consistent concentration of total organic carbon (70.70 +/- 2.96 %) over the millennial timescale. Its conservation was strengthened by burial in dry sandy soils soon after the fire. Raman spectra of the least weathered charcoal fragments of various ages indicate that intensive biomass burning occurred regularly in the Holocene. Capacity to form pyrogenic archives of Keiva II was predetermined by glacial-associated features like kettle topography and their postglacial modification. Rich PyC record of Keiva II highlights the significance of this landform for soilbased paleofire studies in eastern Fennoscandia.

The research is devoted to the analysis of biodiversity of Antarctic cyanobacteria in hypolithic organic-accumulative horizons of soils in the Larsemann Hills oasis. Studies of fouling glasses by the methods of light and confocal microscopy, as well as by fluorescent in situ hybridization, indicate that filamentous forms predominate among cyanobacteria in the upper layers of Antarctic hypolithic microbial communities. Strains of the genera Nostoc , Halotia , Leptolyngbya , Plectolyngbya , and Phormidesmis , as well as some new and previously undescribed cyanobacteria, were isolated from corresponding soil samples to clarify their taxonomic status. As a result, a unique collection of Antarctic cyanobacteria isolated from soils was obtained for the first time. The strains were described according to the modern polyphasic taxonomy methods based on an integrated assessment of morphological and molecular-genetic features. Phylogenetic analysis of primary 16S rRNA sequences and peculiarities of secondary structures of internal transcribed spacers enabled us to identify new taxa of potentially endemic cyanobacteria among the strains studied. The high level of similarity between the 16S rRNA gene sequences of soil strains and those previously found in benthic mats of water bodies in the Larsemann Hills confirmed the ability of cyanobacteria to expand beyond different ecological niches and to adapt to contrasting environmental conditions.

The area of stone pavements on the streets of contemporary cities is increasing especially in pedestrian areas. Following this trend, we expect the new habitats for biocrusts and associated organo-mineral interactions to appear. Pedestrian zones of Moscow represent a vast area of exposed natural hard rock mainly of the granitic origin or concrete paving slabs both ready for the establishment of biocrust. The pavements contain a regular network of inter-block pore spaces filled with autochthonous but mainly allochthonous fine earth conductive to pedogenic processes. The change from the asphalt to discontinuous stone pavement leads to 1–15% increase in the spatial share of small scale soils (5–10 cm deep) located in the inter-slab seams. The other important components of artificial covers in pedestrian areas are the micro profiles (1–2 cm deep) that establish in the stone slabs, they resemble pedogenic horizonation although developed in hard rock. The data on these bodies (soloids) dominated by microbial biocrusts are very scarce in the urban environment. Various combinations of cryptogamic and microbial photoautotrophs contribute noticeably to the carbon and nitrogen budget of the newly established stone pavements in pedestrian areas of Moscow. Top 5 cm of the two-component pavement system could contain 1.20 kg C m –2 and 0.07 kg N m –2 on average, while inter-slab spaces colonized by the moss-dominated biocrust store as much as 7.90 kg C m –2 and 0.42 kg N m –2 . These data suggest pavement systems should be placed among other urban hot spots of C and N accumulation.

The study of microbial complexes in organo-accumulative horizons of Antarctic soils (Cryosols, Leptosols) at the Larsemann Hills and Schirmacher oases and on King George Island has been carried out by the fouling glass method. This method allows one to study the taxonomic composition of microorganisms, features of their morphology, inter-organism interactions, and spatial organization of the complex of microorganisms, as well as to simulate the processes of colonization of mineral surfaces. The investigated microbial complexes can be subdivided into four groups with respect to dominant microorganisms: (1) diverse microbial complexes of King George Island with a considerable portion of diatoms among algae and with a predominance of mycelium in the fungal biomass; (2) complexes of lichen–moss, moss, and algal–moss associations in lake basins with a greater proportion of eukaryotic and coccoid cyanobacteria and with mycelium and sporous forms of micromycetes; (3) complexes of moss and algal–moss associations in the bottoms of wet valleys with a higher proportion of filamentous cyanobacteria and with the absence of fungi, or their presence in the form of short chains of chlamydospores; and (4) hypolithic microbial complexes of rock baths in dry rocky habitats, where the fouling of glasses did not take place. The microbial complexes in different glass samples taken in February–March in different years proved to be at different stages of development. Microscopic mycelium of fungi was not abundant in all algae and moss associations; in some, it was practically absent. Among algae, not cyanobacteria, but eukaryotic algae dominated in a number of habitats: diatoms, green algae, and streptophytes. The totality of the complex features indicated the extremity of the habitat: one morphotype of melanized fungal mycelium dominated in a particular sample; there was no diversity of spore forms, which indirectly indicates a low taxonomic diversity of fungi; multiple chlamydospore formation and microcycles of development were common. Among cyanobacteria, brown and reddish coloration was often found, and the formation of biofilms on glasses was limited to microcolonies, while algal biofilms abundantly covered the soil of the studied horizons. Apparently, extended biofilms were formed over time exceeding the exposure time of the glasses. Hypolithic communities did not colonize new habitats (glasses) for several years of exposure, unlike the bottoms of hydromorphic valleys and lake basins in oases (glasses overgrown in a year) and King George Island (glasses overgrown in 10 days).

Cryoconite is an organomineral sediment on the surface of glaciers. It has predominantly an eolian origin, demonstrates high microbial activity, and contains a relatively large pool of nutrients. When glaciers retreat, the cryoconite material is translocated to the periglacial zone, where it serves as a nutrient-rich fine-textured parent rock component that promotes establishment of initial soils. Here we examine the spatial patterns of cryoconite on the surface of Aldegonda Glacier (Svalbard) and investigate the further pedogenic transformation of cryoconite material in periglacial environments of this rapidly retreating glacier. The data on micromorphology, composition of carbon and nitrogen stable isotopes, and radiocarbon age of different organic matter fractions in cryoconite and cryoconite-influenced periglacial soils are discussed. We demonstrate that soils formed on cryoconite material partially inherit its properties, and the soil formation processes can be accelerated by an order of magnitude compared to the surrounding nutrient-poor and coarse-textured till.

Charred materials (anthracomass) stored within a soil constitute a major part of its pyrogenic archive and could provide evidence of past fire events, both natural and anthropogenic. However, the dynamics of man-made contributions to the total anthracomass of soil at different time scales are insufficiently understood. In this study, we determined the anthracomass concentrations, stocks, and particle-size distribution in anthropogenically transformed soils of different genesis and ages. Materials were collected from the following archaeological sites within Central Russia—3 Upper Paleolithic sites (Avdeevo, Khotylevo-2 and Yudinovo-1), 2 Early Iron Age settlements (Khotylevo-2 and Yaroslavl), and 1 Medieval site (Yaroslavl). Samples from different cultural layers (CLs), plough layers, and native soils (control) were studied. We identified anthracomass accumulation over a wide chronological scale starting from the Upper Paleolithic Period. The high degree of preservation of anthracomass in ancient anthropogenically transformed soils was explained by the presence of large fragments of charred bones, which are more durable in comparison to wood charcoal. The anthracomass concentrations and stocks in the Early Iron Age plough layer were lower than those in the Medieval plough layer. CLs were generally more enriched in the anthracomass than plough layers, due to their sedimentational genesis, which is more favorable for anthracomass preservation than the turbational genesis of plough layers. However, the differences between charred particle sizes in synlithogenic CLs and turbational plough layers were less clear than expected, due to the specific conditions of formation of each particular layer, e.g., burial rate, duration of ploughing, and type of agricultural land use.

Previous studies have shown that a significant part of the bacterial communities of Antarctic soils is represented by cells passing through filters with pore sizes of 0.2 µm. These results raised new research questions about the composition and diversity of the filterable forms of bacteria (FFB) in Antarctic soils and their role in the adaptation of bacteria to the extreme living conditions. To answer such questions, we analyzed the succession of bacterial communities during incubation of Antarctic soil samples from the Bunger Hills at increased humidity and positive temperatures (5 °C and 20 °C). We determined the total number of viable cells by fluorescence microscopy in all samples and assessed the taxonomic diversity of bacteria by next-generation sequencing of the 16S rRNA gene region. Our results have shown that at those checkpoints where the total number of cells reached the maximum, the FFB fraction reached its minimum, and vice versa. We did not observe significant changes in taxonomic diversity in the soil bacterial communities during succession. During our study, we found that the soil bacterial communities as a whole and the FFB fraction consist of almost the same phylogenetic groups. We suppose rapid transition of the cells of the active part of the bacterial population to small dormant forms is one of the survival strategies in extreme conditions and contributes to the stable functioning of microbial communities in Antarctic soils.

Recent detailed investigations of landforms, soils and surface deposits of the Borisoglebsk Upland northeastern slope within the Nero Lake basin (Central European Russia, Yaroslavl Region) allowed deciphering co-evolution of the major landscape components of the case study area since the Late Pleistocene. The Late Pleistocene to Holocene transition in the gully network was represented by relatively short but high-magnitude (up to 12 m) incision phase followed by significant infill till 6.5 ka. Absence of the well-developed early Holocene paleosols in the studied sections and cores suggests dominantly negative sediment budget. There is so far limited evidence of sedimentation over the first half of the Holocene. Discontinuous deposition with certain interruptions (but without distinct buried soil formation) occurred only within closed depressions and on gully fans. The second part of the Holocene prior to the widespread human settlement left more substantial traces in soil and sediment record. Despite the common perception of the pristine boreal forest landscapes to be geomorphologically stable due to erosion-protective role of woodland vegetation, several phases of dramatically increased soil and gully erosion rates have been identified. It is identified in soil bodies and sediments, both at locations dominated by denudation (evidences of multiple topsoil truncation in Atlantic and Subatlantic) and at zones of alternating incision and infill of small linear erosion features. Such extremes were most likely associated with combination of several triggers including natural forest fires and high-magnitude rainfall or snowmelt runoff events. There are several 14C dated layers of pyrogenic charcoal indicating pre-anthropogenic wildfire-induced incision and infill cycles during the middle and late Holocene.The last phases of increased hillslope and fluvial activity within the study area can be related to increased human interference, starting from about 1600-900 years ago. The onset of cut-and-burn cultivation is independently established from available archeological evidences, dating of cut and burnt tree logs remnants, organic material buried by agrogenic colluvium and gully fans. Latest period of intensive gully growth can most likely be attributed to the XIXth Century land tenure reform, when most of the study area gullies experienced significant linear growth, bottom incisions and appearance of several new gully branches. The most recent trend of soil and gully erosion has been evaluated by 137Cs sediment tracing, soil empirical modeling and comparison of historical and modern maps, airborne photos and satellite images. Rates of soil redistribution on slopes decreased significantly over the last several decades due to combination of natural and anthropogenic impacts: 1) decreased spring snowmelt runoff caused mainly by generally lowered thickness of seasonally frozen topsoil layer; 2) arable land abandonment or shift from row crops and cereals to perennial grass-dominated crop rotations in the post-Soviet period. In addition, local short-term (from several years to within-year) cycles of relatively low-magnitude (not exceeding ±1 m range) incision and infill in gullies are often triggered by biogenic activities, namely beaver dam constructions and breaches and local log jams.The study is supported by the Russian Science Foundation (Project No. 19-77-10061) and Russian Foundation for Basic Research (Project No. 19-29-05238).

The vegetation cover and the chemical and physical properties of strongly skeletal residual-calcareous pelozems (Skeletic Leptosols (Loamic)), carbopetrozems (Calcaric Leptosols (Protic)), petrozems (Skeletic Leptosols (Protic)), and cryozems (Oxyaquic Cryosols (Loamic)) in the northern part of the Novaya Zemlya archipelago are described. The reserves and structure of microbial biomass, the intensity of СО2 (basal and substrate-induced respiration), СН4 (methanogenesis), and N2O (denitrification) emissions in the soil samples have been determined. The biomass of microorganisms (prokaryotes and fungi in total) varies from 22.50 to 390.18 μg/g soil. The share of mycobiota in the microbial biomass reaches 80–98%. Most of the microbial biomass (up to 50%) is concentrated in the surface horizons. The number of prokaryotes ranges from 1.5 × 107 to 9.66 × 108 cells/g soil, and the biomass of fungi varies from 22 to 372 μg/g soil. The length of the actinomycete mycelium is small: from 0.6 to 23.5 m/g soil, and the length of fungal hyphae is an order of magnitude higher (up to 166 m/g soil). All parameters of the biological activity of the studied soils sharply decrease down the soil profiles being positively correlated with the contents of organic matter, carbon, and nitrogen. In general, the values of the studied indicators of the biological activity of soils in the north of Novaya Zemlya are lower than those in soils located 3°–5° to the north, on Franz Josef Land. This phenomenon is explained by the influence of the largest glacier in Russia on the soil and vegetation cover on the adjacent territory in the north of Novaya Zemlya.

Soils and sediments serve as complementary sources of detailed information on paleofires in various ecosystems. Despite the abundance of charcoal material entrapped in soils they remain relatively less studied pyrogenic archives in comparison to the sedimentary paleofire records (e.g. lacustrine and peat deposits), and that is especially the case for the most territory of Russia. We report here on the numerous soil archives of the Holocene forest fires at the Kola Peninsula (66.347°N, 37.948°E) and the north of Arkhangelsk region (64.747°N, 43.387°E) in Russia. Series of buried Podzols (up to ten successive profiles) separated by the distinct charcoal layers were revealed in specific geomorphological traps like the thermokarst depressions inherited from the early stages of moraine sediments formation (Kola Peninsula), as well as in active and paleokarst sinkholes in carbonate and sulfate rocks (Arkhangelsk region). The maximum temporal depth of archives was estimated as 10261±40 cal yr BP for the key site in Arkhangelsk region, with up to 12 major pyrogenic events recorded at the local scale. Soil formation at the inter-pyrogenic stages maintained a uniform direction for at least 10 thousand years and profiles of Podzols were regularly replicated at all the key sites. We employ here a combination of soil morphological hierarchical analysis, study of geomorphological processes leading to the burial of pyrogenic carbon, 14C dating of charcoal and TOC derived from the soil organic matter, carbon and nitrogen isotope ratio mass spectrometry and anthracomass concentrations analysis to extract a set of paleoenvironmental information from these soil archives. The study of complementary pyrogenic archives in the three-component system of the karst landscape (including bottom and slopes of the funnels, as well as the flat elevated areas between them) helped to mitigate overestimation or underestimation of the anthracomass concentration and allowed to acquire a detailed dataset on paleopyrogenic events at the local scale. This study is supported by the Russian Foundation for Basic Research, Project No. 19-29-05238.

Pyrogenic carbon constitutes a significant portion of organic carbon in soils of the planet, and in some soils its share raises to 30%. The charcoal-rich archives of forest paleofires are often localized in the geomorphological traps that reveal numerous profiles of pyrogenic soils buried due to the repeated post-fire episodes of erosion and accumulation. The paleokarst and active karst landscapes provide a unique matrix that records pyrogenic and depositional events of the past at the local scale. Polypyrocyclical Podzols of the karst landscapes at the north of the Arkhangelsk region (Russia) are the objects of this study. The fields of closed karst funnels (n x 10 m in diameter, 1–5 m elevation difference) demonstrate accumulative and denudation models of soil formation that are realized at the close distance with the pyrogenic soil archives of the bottoms, slopes and high flat sides of the funnels complementary to each other. This regular grid of archives contains information on pyrogenic events and stages of soil formation throughout the Holocene. We report and discuss here 42 radiocarbon dates (AMS) obtained both for the charcoal material and the total organic carbon (TOC) of the soil organic matter. The 14C age (conventional) of charcoal from the lowest horizons was as old as 9115±30 BP - 8770±30 BP, and the charcoal material of the top pyrogenic horizons was as young as 325±20 BP - 45±20 BP. The 14C age of the soil TOC was in general younger than the age of charcoal enclosed in this soil material. We combine the study of soil horizons morphology and stratigraphy with the set of 14C data to experiment with the several age-depth models explaining post-pyrogenic sedimentation rates on various geomorphological elements of the karst landscape. This study is supported by the Russian Foundation for Basic Research, Project No. 19-29-05238.

Despite the abundance of charcoal material entrapped in soils, they remain relatively less studied pyrogenic archives in comparison to the sedimentary paleofire records (e.g., lacustrine and peat deposits), and that is especially the case in most of Russia’s territory. We report here on the deep soil archives of the Holocene forest fires from the Pinega District of the Arkhangelsk region (64.747° N, 43.387° E). Series of buried soil profiles separated by charcoal layers and clusters were revealed in specific geomorphological traps represented by the active and paleokarst subsidence sinkholes on sulfate rocks overlaid by glacial and fluvial deposits. We combine the study of soil morphology and stratigraphy with a set of radiocarbon data on charcoal and soil organic matter, as well as the anthracomass analysis, to extract a set of paleoenvironmental data. A total of 45 radiocarbon dates were obtained for the macrocharcoal material and the soil organic matter. The maximum temporal “depth” of archives estimated from the radiocarbon dating of macrocharcoal reached 10,260 ± 35 cal yr BP. Soil formation with Podzols established at the inter-pyrogenic stages repeatedly reproduced within the period of ten thousand years, while the dominant tree species was Pinus sp. According to the macrocharcoal data, the intervals between fires have shortened in the last thousand years. Dendrochronological estimates suggest the occurrence of fires in almost every decade of the 20th and early 21st centuries. This is the first study of the millennia-scale soil record of forest fires in this particular region of Russia.