Data on the molecular structure of humic substances (HSs) of zonal soils for the southern, middle, northern taiga and southern tundra of northeastern European Russia have been obtained. This was accomplished using solid-state 13C nuclear magnetic resonance (13C NMR) technique. The soils under study vary in the point of genesis and degree of hydromorphism. The impact of environmental factors (temperature and humidity) on qualitative and quantitative composition of humic (HAs) and fulvic acids (FAs) has been determined. Excess moisture significantly affects HS accumulation and HS molecular structure: hydromorphic taiga soils accumulate HSs enriched by unoxidized aliphatic fragments, tundra soils – the ones enriched by carbohydrate fragments. Various conditions of soil genesis predefine the specific character of structural and functional parameters of HSs in the southern taiga to southern tundra soils, as is expressed through the increased portion of labile carbohydrate and amino acid fragments and methoxyl groups within the structure of HSs. The tundra humification is characterized by levelling-off of structural and functional parameters of major classes of specific organic compounds of soils – HAs and FAs.
The purpose of the work is to provide a comprehensive review of the available historical and current records of vagrant and visiting individuals sighted at the Haswell archipelago, near the Russian Antarctic station Mirny (Davis Sea, southern Indian Ocean), from 1956 to 2016. Three rare vagrant species (eight observations) were recorded: the Chinstrap Penguin (Pygoscelis antarctica), Macaroni Penguin (Eudyptes chrysolophus) and Kelp Gull (Larus dominicanus). The Southern Giant Petrel (Macronectes giganteus; ten observations) and Pomarine Jaeger (Stercorarius pomarinus; a single observation) were visitors of the archipelago. Southern Giant Petrels and all vagrant individuals are of southern origin, the Pomarine Jaeger is a Holarctic breeding species. A single vagrant (and one uncertain case) appeared in the austral spring, and another eight – in the summer. Three cases of visitors were recorded in the austral spring, and eight in the summer. Records of vagrancy and visitors cover the dynamic period of changes in ice conditions. While most vagrants and visitors were sighted only for one day, two Macaroni Penguins stayed for several days at the archipelago. The most detailed issues in this work are those related to the study of vagrancy. I evaluate the possibilities of limited existence of vagrants and visitors into groups of endemic species as well as interspecific interactions. I also discuss the physical condition of vagrant individuals and factors contributing to their survival, ponder on the origin of vagrant individuals and visitors, their association with specific populations and causes of vagrancy.
The harsh polar environment results in the dominance of mosses and liverworts in tundra communities. To date, very little research has been devoted to the diversity and ecology of these groups in the High Arctic. The aim of this research was to investigate the diversity and community composition of mosses and liverworts in various stages of the ecogenesis of Svalbard ecosystems, and to identify environmental factors affecting species distribution. In 2017, 270 plots were established in a grid in eight glacier forelands and the mature tundra surrounding them. Within these plots, the percentage cover of mosses and liverworts was investigated. In 201 plots, soil samples were taken and environmental data (aspect, bare ground cover, biological soil crust cover, distance from the glacier forehead, rock cover, slope, time elapsed since the glacier’s retreat, Topographic Wetness Index, and total insolation) were obtained. In total, 105 species were recorded. Species number and composition depended on effects of both habitat type (foreland and mature tundra) and the geographical locations of glaciers, while species cover was also associated with the interaction between those factors. The following factors affected species distribution: cover of bare ground and vascular plants, distance from the glacier forehead, soil conductivity, contents of total organic carbon and total nitrogen in soil, K+ content, silt and sand contents, soil pH, time elapsed since the glacier’s retreat, and total insolation. In the glacier forelands, mosses and liverworts are less exposed to competition from other species. Therefore, in the future, if global warming progresses at its current rate, forelands may serve as important species refugia.
Main aim of the study was to search for possible differences in diatom colonization and their communities under the influence of glacier meltwater inflow and when unaffected by glacier meltwater, and also to define the time needed for the development of diatom communities on newly submerged substrates at small depths in Antarctica. We used artificial substrates (Plexiglass© tiles), submerged at a depth of 1 m below the sea surface at two locations at the South Bay of Livingston Island: (1) Johnsons Dock – a cove, known to receive glacier meltwater with sediments, and (2) outside the cove, generally unaffected by glacial meltwater. Samples from the natural epilithon at similar depth were also taken as a reference for diatom community structure. Statistical testing the differences between the two sites was not possible this time, but the samples allowed us to compare the sites in terms of diatom growth, species richness, diversity and evenness changes in diatom communities along the time of the experiment at both sites and with the natural epilithon at similar depths. Diatom colonization followed the three-phases scheme (colonization, logarithmic growth and equilibrium) as in other latitudes. Based on the valve density and community indices e.g. species richness, diversity (1-D) and evenness (J’), we consider that at least three weeks might be necessary to obtain sufficiently representative for the environment diatom communities on new substrates at small depths in Antarctica, in conditions similar to those of South Bay. No particular differences between the sites were noted in the colonization scheme, but the diversity (1-D) and evenness (J’) were higher at glacier influenced site, as well as the number of the valves on the substrates. Sea ice diatoms prevailed at the glacier influenced site. We suggest that species exchange between the sea ice and other hard substrates do exist, at least for some taxa, and such species might be indicative for variations in both salinity and water transparency, related to glacial meltwater inflow.
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