A. V. Lupachev

Soil Formation and the Underlying Permafrost

The composition and fabric of the upper permafrost layer and its relationships with the permafrost-affected soils developing from the loamy substrates on the interfluves within coastal lowlands of northern Yakutia are considered. The studied area is characterized by the maximum activity of cryogenic processes and a shallow depth of seasonal thawing. The permafrost layer affected by the maximum thawing during the Holocene has a specific morphology attesting to the impact of soil processes on it. In general, the modern soil profile and the underlying permafrost layer can be distinguished as the soil-permafrost complex. It is subdivided into the soil profile, the transient layer, and the intermediate layer. The morphology and properties of the transient layer depend on the character of the soil horizons above the permafrost table. The lateral migration of raw organic substances takes place above the permafrost surface between the particular elements of the cryogenic soil complexes; this material tends to accumulate within the transient layer.

Suprapermafrost organic-accumulative horizons in the tundra cryozems of northern Yakutia

Organic-accumulative horizons above the permafrost table have been described in the profiles of cryozems developing on interfluve surfaces in the tundra zone of northern Yakutia. The organic matter content in these suprapermafrost horizons is comparable with or even exceeds the organic matter content in the surface horizons. The dynamics of seasonal thawing specify the annual involvement of the material of these horizons into the zone of active pedogenesis or its exclusion from it in the case of their frozen state. The analysis of the morphology of cryozems of the Kolyma Lowland along a 1000-km-long sublatitudinal transect shows that the accumulation and migration of raw organic materials (predominantly, differently decomposed peat) above the permafrost table take place upon the particular combinations of local factors (the soil moistening, ice content, freezing-thawing conditions, nanotopography of the permafrost table, etc.) at the lower boundary of the active layer. The well-pronounced accumulation of the raw organic material in the suprapermafrost horizons can be reflected in the substantive characteristics of these horizons and should be taken into account in classification decisions.

Soils of MacRobertson Land

MacRobertson Land is the portion of Antarctica lying south of the Mawson Coast between 59° 34′ E and 72° 35′ E. At 5,400 km2, MacRobertson Land constitutes the third largest ice-free area in Antarctica, accounting for 11 % of the total ice-free area. Less than 10 % of the ice area occurs along the coast. It has five major ice-free areas: (i) the Northern Prince Charles Mountains, including the Amery Oasis, (ii) the Southern Prince Charles Mountains, including the Mawson Escarpment, (iii) the Grove Mountains, (iv) a series of small coastal oases and inland Framnes Mountains along the Mawson Coast, and (v) the Vestfold Hills, Rauer-Bolingen Islands, and Larsemann Hills along the Ingrid Christensen Coast. Elevation differences of over 3,000 m and distances of ice-free areas from the coast up to 650 km inland create sharp contrasts in climatic conditions and have a marked impact on pedogenesis. Permafrost is continuous in MacRobertson Land. Active-layer depths range from 25 cm in the Grove Mountains to 110 cm or more on the coast. Patterned ground is ubiquitous in the areas with frost-susceptible parent materials throughout the region. Soil-forming processes can be examined along an elevational-longitudinal gradient from the Vestfold-Larsemann Hills to the southern Prince Charles and Grove Mountains. Salinization, manifested in salt efflorescence, carbonation, and permafrost development are expected to increase from the coast inland; pervection, and soil organic matter accumulation are greatest along the coast. Desert pavement formation and rubification are important processes along the entire gradient. Unlike Wilkes Land and South Shetland Islands, podzolization has not been reported in MacRobertson Land. The dominant soil taxa along the coast are Aquiturbels, Haploturbels, previously unclassified ornithogenic and limnogenic soils, and endo- and epi-lithic soil-like bodies. Lithic Anhyorthels are predominant in the inland mountains.

Microbial biomass and biological activity of soils and soil-like bodies in coastal oases of Antarctica

The method of luminescent microscopy has been applied to study the structure of the microbial biomass of soils and soil-like bodies in East (the Thala Hills and Larsemann Hills oases) and West (Cape Burks, Hobbs coast) Antarctica. According to Soil Taxonomy, the studied soils mainly belong to the subgroups of Aquic Haploturbels, Typic Haploturbels, Typic Haplorthels, and Lithic Haplorthels. The major contribution to their microbial biomass belongs to fungi. The highest fungal biomass (up to 790 μg C/g soil) has been found in the soils with surface organic horizons in the form of thin moss/lichen litters, in which the development of fungal mycelium is most active. A larger part of fungal biomass (70–98%) is represented by spores. For the soils without vegetation cover, the accumulation of bacterial and fungal biomass takes place in the horizons under surface desert pavements. In the upper parts of the soils without vegetation cover and in the organic soil horizons, the major part (>60%) of fungal mycelium contains protective melanin pigments. Among bacteria, the high portion (up to 50%) of small filtering forms is observed. A considerable increase (up to 290.2 ± 27 μg C/g soil) in the fungal biomass owing to the development of yeasts has been shown for gley soils (gleyzems) developing from sapropel sediments under subaquatic conditions and for the algal–bacterial mat on the bottom of the lake (920.7 ± 46 μg C/g soil). The production of carbon dioxide by the soils varies from 0.47 to 2.34 μg C–CO2/(g day). The intensity of nitrogen fixation in the studied samples is generally low: from 0.08 to 55.85 ng С2Н4/(g day). The intensity of denitrification varies from 0.09 to 19.28 μg N–N2O/(g day).

The influence of cryogenic mass exchange on the distribution of viable microfauna in cryozems

The role of cryogenic mass exchange in the distribution of the viable microfauna (ciliates, heterotrophic flagellates, and nematodes) in the profiles of cryoturbated cryogenic soils and in the upper layers of permafrost was revealed. The material for microbiological investigations was collected from the main horizons of cryozem profiles, including the zones with morphologically manifested processes of cryogenic mass exchange (the development of barren spots, cryoturbation, and suprapermafrost accumulation) and the zones affected by solifluction. The radiocarbon dating of the soil samples showed that the age of the organic cryogenic material and material buried in the course of solifluction varied from 2100 to 4500 years. Some zones with specific ecological conditions promoting the preservation of species diversity of the microfauna were found to develop in the cryozem profiles. A considerable part of the community (38% of ciliates, 58% of flagellates, and 50% of nematodes) maintained its viability in the dormant state, and in some cases, it could pass to the state of long-term cryobiosis in the upper layer of permafrost.

Active layer monitoring in Antarctica: an overview of results from 2006 to 2015

Monitoring of active layer thawing depth and active layer thickness (ALT), using mechanical pronging and continuous temperature data logging, has been undertaken under the Circumpolar Active Layer ...

Soils of loamy watersheds of coastal tundra in the north of Yakutia: Pedogenetic conditions and processes

This paper considers regularities governing the formation of automorphic tundra soils on glacial loamy deposits containing relict organic matter mainly represented by very fine plant detritus. Drainage, microtopography, and cryoturbation activity are the major controls of the development of these soils. With an increase in drainage, the following pedogenetic trend is observed on the surface of yedoma (Ice Сomplex) areas: gleyzem–cryozem–cryometamorphic soil. The climate change in the Holocene induced quick transformation of topography and general landscape situation and promoted formation and development of cryogenic soil complexes in the considered territory. Upon the low intensity of pedogenesis, the features and properties of previous soil formation stages are often preserved in the soil profiles; these are: gleyzation, peat accumulation, and cryoturbation.

Suprapermafrost Horizons of the Accumulation of Raw Organic Matter in Tundra Cryozems of Northern Yakutia

In the profiles of cryozems (Oxyaquic Turbic Cryosols) developing in tundra of northern Yakutia under conditions of shallow active layer, suprapermafrost horizons of the accumulation of raw organic matter are formed. Taking into account their genesis, stable and regular position in the soil profile, paragenetic links with the overlying horizons and neighboring soil profiles, and a set of diagnostic features and properties, these horizons can be separated as a new type of genetic soil horizons—the organomineral accumulative suprapermafrost horizon (CRO). Its qualitative composition (the ratio of organic and mineral matter in the material) can be reflected at a lower level. In relation to the separation of the new genetic horizon within the framework of the new Russian soil classification system, a new genetic types of soils—cryozem with suprapermafrost accumulation of raw organic matter (suprapermafrost organo-accumulative cryozem)—can be established. Its diagnostic profile has the following horizonation: (O, AO, T)–CR–CRO–┬C.

The role of frost boils in the development of cryozems on coastal lowlands of northern Yakutia

The influence of frost boils on the development of cryozems (Turbic Cryosols) in the tundra zone of northern Yakutia is discussed. Mechanisms of the input, redistribution, and transformation of raw organic matter with its accumulation in the deep part of the profile of cryozems are elucidated. As a result, specific organomineral or organic horizons are formed above the permafrost table. The development of cryozems has a cyclic pattern: from the stage of barren frost boil to the stage of mature soil profile. However, this cycle can be interrupted at any stage of overgrowing of the barren surface of frost boil. The rates of overgrowing and the formation of the profile of cryozem, and the 14C age of organic matter accumulated in the organomineral suprapermafrost horizons are estimated.

Biogenic–Abiogenic Interaction in Antarctic Ornithogenic Soils

In severe climatic and specific landscape conditions of Antarctica birds play an important role in transportation of organic matter of guano to the coastal landscapes. It has been shown that redistribution of guano components affects the speed of soil cover spatial development and formation of new polypedons of soils in environments, surrounding rookeries. Soils development is also affected by flying birds’ transportation activity, while they transport the viable diasporas of plants, material of limpet shells, etc. This affects an initial or additional colonization of rocks being in distance from the coasts, sources of seed, and organic matter. Soils of Antarctica formed under effect of bird activity are the following: the most known typical ornithosols of the current penguin rockeries, post-Ornithosols, developed during post-Ornithogenic succession and organic lithosols formed in the areas of flying sea birds nesting and feeding areas due to limited nitrification and viable plant material and diasporas transportation.