Alexander A. Sokolov

The importance of willow thickets for ptarmigan and hares in shrub tundra : the more the better?

In patchy habitats, the relationship between animal abundance and cover of a preferred habitat may change with the availability of that habitat, resulting in a functional response in habitat use. Here, we investigate the relationship of two specialized herbivores, willow ptarmigan (Lagopus lagopus) and mountain hare (Lepus timidus), to willows (Salix spp.) in three regions of the shrub tundra zone—northern Norway, northern European Russia and western Siberia. Shrub tundra is a naturally patchy habitat where willow thickets represent a major structural element and are important for herbivores both as food and shelter. Habitat use was quantified using feces counts in a hierarchical spatial design and related to several measures of willow thicket configuration. We document a functional response in the use of willow thickets by ptarmigan, but not by hares. For hares, whose range extends into forested regions, occurrence increased overall with willow cover. The occurrence of willow ptarmigan showed a strong positive relationship to willow cover and a negative relationship to thicket fragmentation in the region with lowest willow cover at landscape scale, where willow growth may be limited by reindeer browsing. In regions with higher cover, in contrast, such relationships were not observed. Differences in predator communities among the regions may contribute to the observed pattern, enhancing the need for cover where willow thickets are scarce. Such region-specific relationships reflecting regional characteristics of the ecosystem highlight the importance of large-scale investigations to understand the relationships of habitat availability and use, which is a critical issue considering that habitat availability changes quickly with climate change and human impact.

Bird Communities of the Arctic Shrub Tundra of Yamal: Habitat Specialists and Generalists

Background The ratio of habitat generalists to specialists in birds has been suggested as a good indicator of ecosystem changes due to e.g. climate change and other anthropogenic perturbations. Most studies focusing on this functional component of biodiversity originate, however, from temperate regions. The Eurasian Arctic tundra is currently experiencing an unprecedented combination of climate change, change in grazing pressure by domestic reindeer and growing human activity. Methodology/Principal Findings Here we monitored bird communities in a tundra landscape harbouring shrub and open habitats in order to analyse bird habitat relationships and quantify habitat specialization. We used ordination methods to analyse habitat associations and estimated the proportions of specialists in each of the main habitats. Correspondence Analysis identified three main bird communities, inhabiting upland, lowland and dense willow shrubs. We documented a stable structure of communities despite large multiannual variations of bird density (from 90 to 175 pairs/km2). Willow shrub thickets were a hotspot for bird density, but not for species richness. The thickets hosted many specialized species whose main distribution area was south of the tundra. Conclusion/Significance If current arctic changes result in a shrubification of the landscape as many studies suggested, we would expect an increase in the overall bird abundance together with an increase of local specialists, since they are associated with willow thickets. The majority of these species have a southern origin and their increase in abundance would represent a strengthening of the boreal component in the southern tundra, perhaps at the expense of species typical of the subarctic zone, which appear to be generalists within this zone.

Red fox takeover of arctic fox breeding den: an observation from Yamal Peninsula, Russia

Here, we report from the first direct observation of a red fox (Vulpes vulpes) intrusion on an arctic fox (Vulpes lagopus) breeding den from the southern Arctic tundra of Yamal Peninsula, Russia in 2007. At the same time, as a current range retraction of the original inhabitant of the circumpolar tundra zone the arctic fox is going on, the red fox is expanding their range from the south into arctic habitats. Thus, within large parts of the northern tundra areas the two species are sympatric which gives opportunities for direct interactions including interference competition. However, direct first-hand observations of such interactions are rare, especially in the Russian Arctic. In the present study, we observed one red fox taking over an arctic fox breeding den which resulted in den abandonment by the arctic fox. On July 19, eight arctic fox pups were observed on the den before the red fox was observed on the same den July 22. The pups were never seen at the den or elsewhere after the red fox was observed on the den for as long as we stayed in the area (until August 10). Our observation supports the view that direct interference with red fox on breeding dens may contribute to the range retraction of arctic foxes from the southern limits of the Arctic tundra in Russia.

Peregrine Falcons kill a Gyrfalcon feeding on their nestling

Resumen La competencia entre depredadores tope es importante para entender las interacciones en las tramas troficas. Sin embargo, existe poco conocimiento sobre la ocurrencia y las consecuencias de la competencia entre aves rapaces que crian en el artico, en parte debido a las dificultades de obtener registros por las caracterisitcas inherentes del area. Las interacciones entre los depredadores tope de la tundra Falco rusticolus y F. peregrinus han sido observadas frecuentemente en el Artico de Norteamerica pero raramente en el Artico de Eurasia, probablemente debido a la escasa superposicion de las areas de cria de estas dos especies de halcones en el Artico europeo. De acuerdo a nuestro conocimiento, este es el primer registro de que halcones de la especie F. rusticolus pueden afectar el exito reproductivo de F. peregrinus al matar a sus polluelos, y que esta depredacion es arriesgada ya que los adultos de F. peregrinus pueden herir o matar a los halcones F. rusticolus. Este caso de interaccion agresiva...

Effect of Al(OH)3 in Enhancing PbSnF4 Anode Performances for Rechargeable Lithium-Ion Battery

Two-phase Al(OH)3–PbSnF4 composites (concentrations of aluminum hydroxide are equal to 5 wt.%, 15 wt.% and 30 wt.%) has been prepared by high-energy ball-milling method. The materials were employed as anodes in Li-ion batteries. It was established that PbSnF4-based systems yield high initial capacity of 800–1100 mAh g–1. The reversible specific capacity of Al(OH)3–PbSnF4 (aluminum hydroxide – 15 wt.%) after 10-fold charge–discharge cycling in the range of 2.5–0.005 V attains 120 mAh g–1, while the specific capacity of pure PbSnF4 is equal only to 20 mAh g–1. It has been shown that the deviation from 15 wt.% concentration of Al (OH)3 decreases cycling stability of lead fluorostannate (II).

α-MoO3 Nanostructure Synthesized in Plasma by an Original Method of Pulsed High-Voltage Discharge as Highly Reversible Anode for Secondary Lithium-Ion Battery

A new concept for synthesis of the nanostructured transition metal oxides had been proposed. In particular, the method of pulsed high-voltage discharge was adopted for synthesis of α-MoO3 nanostructure with orthorhombic crystal lattice. The as-prepared α-MoO3 was investigated as anode for Li-ion battery. The 30-fold charge–discharge cycling has shown that material specific capacity (approximately 90 mAh g–1) is not high, however excellent reversibility was achieved (the Coulombic efficiency equals to 99.9%). Thus the method opens new ways for the synthesis of nanomaterials with stable reversible capacities for Li-ion batteries.

Effect of Hf-doping on electrochemical performance of anatase TiO2 as an anode material for lithium storage

Hafnium-doped titania (Hf/Ti = 0.01; 0.03; 0.05) had been facilely synthesized via a template sol–gel method on carbon fibre. Physico-chemical properties of the as-synthesized materials were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, scanning transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis and Brunauer–Emmett–Teller measurements. It was confirmed that Hf4+ substitute in the Ti4+ sites, forming Ti1–xHfxO2 (x = 0.01; 0.03; 0.05) solid solutions with an anatase crystal structure. The Ti1–xHfxO2 materials are hollow microtubes (length of 10–100 µm, outer diameter of 1–5 µm) composed of nanoparticles (average size of 15–20 nm) with a surface area of 80–90 m2 g–1 and pore volume of 0.294–0.372 cm3 g–1. The effect of Hf ion incorporation on the electrochemical behaviour of anatase TiO2 in the Li-ion battery anode was investigated by galvanostatic charge/discharge and electrochemical impedance spectroscopy. It was established that Ti0.95Hf0.05O2 shows significantly higher reversibility (154.2 mAh g–1) after 35-fold cycling at a C/10 rate in comparison with undoped titania (55.9 mAh g–1). The better performance offered by Hf4+ substitution of the Ti4+ into anatase TiO2 mainly results from a more open crystal structure, which has been achieved via the difference in ionic radius values of Ti4+ (0.604 Å) and Hf4+ (0.71 Å). The obtained results are in good accord with those for anatase TiO2 doped with Zr4+ (0.72 Å), published earlier. Furthermore, improved electrical conductivity of Hf-doped anatase TiO2 materials owing to charge redistribution in the lattice and enhanced interfacial lithium storage owing to increased surface area directly depending on the Hf/Ti atomic ratio have a beneficial effect on electrochemical properties.

Publisher Correction to: Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome

The above mentioned article was originally scheduled for publication in the special issue on Ecology of Tundra Arthropods with guest editors Toke T. Høye . Lauren E. Culler. Erroneously, the article was published in Polar Biology, Volume 40, Issue 11, November, 2017. The publisher sincerely apologizes to the guest editors and the authors for the inconvenience caused.

A novel method for synthesizing nanoscale superionic MF–Sn2F5 (M = K, Cs) solid electrolytes

Cesium and potassium pentafluorodistannites have been synthesized through “wet” high-energy ball milling and characterized through XRD, SEM techniques. The electrical conductivity of the systems have been investigated in the temperature range from 373 K to 513 K by means of impedance spectroscopy. It has been shown that the frequency dependent conductivity of the present system shows the power law feature. Thermally induced phase transitions has been confirmed as well as activation energy calculated from temperature variation of dc conductivity. It has been shown that synthesis in a wet medium enables one to obtain nanoparticles much smaller than in the case of “dry” milling.

Facile synthesis of nanostructured transition metal oxides as electrodes for Li-ion batteries

At all times, energy storage is one of the greatest scientific challenge. Recently, Li-ion batteries are under special attention due to high working voltage, long cycle life, low self-discharge, reliability, no-memory effect. However, commercial LIBs usage in medium- and large-scale energy storage are limited by the capacity of lithiated metal oxide cathode and unsafety of graphite anode at high-rate charge. In this way, new electrode materials with higher electrochemical performance should be designed to satisfy a requirement in both energy and power. As it known, nanostructured transition metal oxides are promising electrode materials because of their elevated specific capacity and high potential vs. Li/Li+. In this work, the perspective of an original facile technique of pulsed high-voltage plasma discharge in synthesis of nanostructured transition metal oxides as electrodes for lithium-ion batteries has been demonstrated.