The vegetation of the Kuril Islands remains insufficiently explored due to their remote location and harsh environment. Understanding the factors that influence vegetation distribution in this extensive volcanic chain of islands, spanning over a thousand kilometers, is important for global biogeography. Our paper presents the first vegetation map of Kunashir Island from the Kuril archipelago, compiled using Sentinel-2 medium-resolution multispectral satellite imagery, incorporating original field research data and the Random Forest machine-learning algorithm. The temperate broad-leaved forests are mainly composed of Acer mono subsp. mayrii and Quercus mongolica, predominantly limited to the southwestern coast, and true-boreal dark-coniferous Abies sachalinensis–Picea jezoensis forests located in the northeast part of Kunashir. The vegetation distribution pattern is associated with the warming effect of the Soja current on the east coast of Kunashir Island and the cooling effect of the Kuril current on the west coast. Kunashir's vegetation displays features of an ecotone between temperate and boreal zones. Still, the boundary between these zones should be drawn within the island, rather than between Kunashir and Hokkaido or Kunashir and Iturup, as suggested in some previous biogeographic generalizations.

Today, changes in terrestrial ecosystems-forests, marshes, tundras, meadows, steppes-as a result of increasing anthropogenic pressures and climate warming, transform the evolutionary structure of Russia's vegetation cover on a large scale, which increases environmental and economic risks. A comprehensive study of all the components and mechanisms of the functioning of terrestrial ecosystems will allow us to develop an approach to managing natural resources under conditions of their intensive exploitation, preserve the gene pool and biodiversity, and determine a nature management strategy. Under the current climate changes, it is the condition and normal functioning of land ecosystems that have become strategically important factors of stability, providing the human environment with basic resources (air, water, food), and of Russia's economic growth.

Tropical cyclones that swept across South Sakhalin and the southern part of the Kuril Islands in early October of 2015 produced strong winds and heavy precipitation.They resulted in large-scale windthrow patches in zonal dark-conifer forests do minated of Abies sachalinensis and Picea jezoensis, as well as secondary forests of va riouscomposition.Weidentifiedthedistributionof thesewindthrows,estimated their area, and assessed the total wood biomass loss.Forest change area and wood bio mass data by Global Forest Watch project was used for the analysis.Through com pa rison examination of these data with satellite images of very-high resolution we established that windthrows located on Sakhalin Island are recognized with highaccuracy,whiletheirareaontheKurilIslandsispresentedsignificantlylower than the area of actual damages.We recommend using methods of higher preci-sionlevelforfuturewindthrowidentificationsontheKurilIslands.Thetotalarea of windthrows on Sakhalin was calculated at 425.98 km 2 with the wood mortality of 4.72•10 6 tons.Wefoundnosignificantcorrelationbetweenwindthrowpatch dis tribution and local topographic conditions such as elevation above sea level and slope gradient.At the same time, forests growing on slopes with western exposure on Sakhalin Island revealed greater damage which is correlated with the wind direction during the disturbance events.K e y w o r d s : windthrow, forest disturbance, forest loss, tropical cyclone, typhoon Р Е З Ю М Е Корзников К.А., Кислов Д.Е., Беляева Н.Г.Массовые ветровалы в тем но хвойных бореальных лесах юга Сахалина и Южных Курил вслед ствие прохождения тропических циклонов в октябре 2015 года.Тро пи чес кие циклоны, прошедшие над южной частью Сахалина и южными Курильскимиостровамивначалеоктября2015года,вызвалисильныевет ра иобильныеосадки.Результатомихвоздействиясталопоявлениемасштаб ныхветроваловвзональныхтемнохвойныхлесахизAbies sachalinensisиPicea jezoensis,атакжевторичныхлесахразличногосостава.Мыопределилиразме ще ниеветровальныхучастков,оценилиихплощадьиобщиепотеридреве си ны.Для этого использовали данные Global Forest Watch о сокращении лес ной площади и биомассе древесины.Сравнив эти данные с изображе ни ями космических снимков сверхвысокого разрешения установили, что вет ро валь ные участки

Tropical cyclones (hurricanes and typhoons) cause large-scale disturbances in forest ecosystems all over the world. In the summer of 2016, a strong tropical cyclone named Lionrock created windthrow patches in the area of more than 400 km2 on the forested eastern slopes of the Sikhote-Alin Range, in the Russian Far East. Such large-scale forest destruction by wind had never been recorded in the area prior to this event. We examined the tropical cyclone impact upon the forest composition, structure and tree mortality rates on two study sites (1 ha and 0.5 ha in size)—a contiguous windthrow patch site, and a site with partial canopy damage. Korean pine (Pinus koraiensis Siebold and Zucc.), Manchurian fir (Abies nephrolepis Trautv.) and Dahurian larch (Larix cajanderi Mayr.) were the primary tree species represented in the affected forest communities. Combined with the partial canopy damage, 7.7% of trees were blown down by the disturbance event. We determined that this one event mortality rate nearly equaled the average mortality rate for a ten year period for these forests (8.5 ± 4.0%) under normal conditions (no large-scale disturbances). Within a contiguous windthrow patch, tree mortality was determined to be 52.6%, which is significantly higher than the cumulative tree loss for the previous 50 years (42.4%). A substantial portion of thinner-stemmed trees (DBH (diameter measured at breast height) < 30 cm) were wind snapped, and those with larger diameters (DBH > 60 cm) were uprooted. Our results indicate that the probability of tree loss due to catastrophic wind loads increases as a result of the decrease in local density. We believe that tree loss estimates should include the impacts within contiguous patches of windthrows, as well as the patches with only partial tree canopy damage. Strong wind impact forecasting is possible with accounting for species composition within the stand sites and their spatial structure.

Modeling of the bioclimatic niches of the complex of tall herb communities in the current and predicted climatic conditions by 2070, as well as in the conditions of the climate of the Last Glacial Maximum (about 21 thousand years ago), has been performed. The most important bioclimatic parameters controlling the geographical distribution of tall herbs are the amount of snow precipitation (snow depth), Kira's warmth and coldness indices, and the continentality index. Under the conditions of the Last Glacial Maximum, bioclimatic refugia of tall herbs could be preserved on the Kuril Islands, but were absent on Sakhalin Island and Kamchatka Peninsula. Current trends of climate change will lead to an increase of the area suitable for tall herb communities in the Russian Far East, but will reduce their distribution in Japan.

This paper deals with food selectivity in large herbivores of Eastern Mongolia, its factors, and their impact on the herbivore community structure. It is shown that, due to the degradation of vegetation, all studied herbivores display a significant selectivity level conditioned by their morpho–physiological features and spatial distribution. The selectivity seems to provide competitive advantages but no food niche differentiation. We suppose that herbivore communities in Eastern Mongolia, both human-controlled and wild, bear an increase of the small browser portion under pasture degradation. This, in turn, increases the degradation rate. This cyclic interaction shows a possible mechanism for the formation of endogenous crises in herbivore communities and can explain features of extinction events of large herbivores of the “Mammoth fauna.”

The size of Rhododendron sichotense seeds and exotesta cells from 20 populations were studied using a scanning electron microscope (SEM). The results of a correlation analysis showed that seed size depends on bioclimatic factors. As a species marker, we used the exotesta cell elongation coefficient. This characteristic was unresponsive to environmental variables, demonstrating its taxonomic significance. In the centre of the species range, the samples had an exotesta cell elongation coefficient that was typical for the species, but in samples from the far northern and southern parts of the range, where the distribution of R. sichotense meets that of of R. dauricum L. and R. mucronulatum Turcz., respectively, the value of the exotesta cell elongation coefficient was intermediate between these species. Therefore, the exotesta cell elongation coefficient can be recommended for use in the detection of hybridisation areas.

An algorithm for environmental map construction is suggested based on the comparative analysis of the relationships between environmental factors and categories of biota, the integral measure of consistency between random events and the measure of similarity between descriptive sets being used. For probability measures, the variance formulae are given. A fragment of an environmental map is constructed for the given region of the taiga ecosystem.

A method of estimating the stability of the problem of orbit determination under disturbances caused by finite accuracy of calculation and geographical siting of observation stations is proposed.

A model of a physical experiment to estimate the speed of gravitational interaction from observations of the geocentric orbits of an artificial satellite in the framework of the consistent Lagrange formalism of the retarded-potential hypothesis is considered. It is shown that it is mathematically correct to postulate the corresponding inverse problem, and results are presented of its numerical investigation, including local estimates of the accuracy of the solution.