Vol 11, No 4 (2018)

This review is devoted to the ecological mechanism for the transformation of the population of the psychrophilic saprozoobiont pseudotuberculosis microbe Yersinia pseudotuberculosis O:1b into the population of the obligate blood plague microbe Yersinia pestis in the host–parasite system of the marmot flea (Marmota sibirica–Oropsylla silantiewi). The correspondence of this mechanism to the evolutionary principle of quantum speciation has been shown. The most significant population–genetic microbial transformations took place in the populations of hibernating marmots. The main factor of rapid speciation was the heterothermic and, accordingly, heteroimmune state of host marmots during hibernation. During winter awakenings, the body temperature of marmots increases in an S-shaped manner from 5 to 37°C within a short period of time (from dozens of minutes to several hours). A drastic acceleration of metabolic and immune processes occurs in the temperature range of 20–30°C. Rapid adaptation to the “explosive” increase in the immune activity of the primary host (tarbagan marmot) during its regular winter awakenings was the essence of the process of Y. pestis speciation.

We compared three approaches to study climatic signals of Pinus sylvestris and Larix sibirica treering width chronologies from the forest-steppe zone of South Siberia, where both temperature and precipitation limit the conifer tree growth: 1—paired correlation of chronologies with monthly climatic variables; 2— paired and partial correlations with monthly and seasonal series of primary and secondary climatic factors, calculated in the Seascorr program; 3—paired correlation with a 15-day moving average series of climatic variables. The comparison showed that simple paired correlation with monthly series as the simplest approach could be used for a wide range of dendroclimatic studies, both as a main procedure and for preliminary analysis. The Seascorr analysis is the most suitable for assessing climate-growth relationship in extreme growth conditions and for reconstructions of extremes, e.g. droughts, and of their impact periods. The application of the 15-day moving average series is limited by availability of daily climatic data, but it describes the seasonal window of climatic response with high precision. Altogether, the combination of three approaches allowed to explore the spatial-temporal pattern of the conifers radial growth climatic response in South Siberia.

The influence of climate changes on larch (Larix sibirica Ledeb.) radial increment under conditions of a limited (forest steppe) and sufficient (high-altitude Kuznetsk Alatau, floodplain stands) humidification is considered. The relationship between growth index of larch trees (N = 257) and ecological and climatic variables is analyzed. In the forest steppe, with the onset of warming, a decrease in the aridity of the climate, an increase in the duration of the growing season (1980s), and an increase in the larch growth index followed by its depression in the 1990s have been observed. Radial-increment depression is caused by an increase in vapor-pressure deficit and arid climate due to a rising air temperature. In the 2000s, radial-increment fluctuations with average values not exceeding those before the beginning of current climate warming period occurred. In the highlands, since the 1970s, there has been a general increase in the larch radial increment closely associated with the main limiting factor of growth—air temperature. At the same time, in arid years, the radial-increment depression of larch trees in highland and floodplain larch forests is also noted. When implementing “hard” climate scenarios (RCP 6.0 and RCP 8.5), it is likely that the larch growth index in a forest steppe will decrease further and its increase in areas of sufficient moisture will be observed.

The territory of the new mass outbreak of Dendrolimus sibiricius is northernmost Siberia. The present increase in the pest numbers started in 2011–2012, 14 years after the previous mass outbreak. As a result, the area of damage to dark coniferous forests exceeded 1.4 million ha. The reasons for the emergence of the pest population from a depressive state are insufficient moisture availability in May 2011, severe droughts in June–July 2012, and increased mean monthly temperature. A significant decrease in the vegetation index of SWVI occurred in 2011–2012. The hydrothermal regime of the spring–summer period in these years promoted the transition of most of the pest populations to development over 1-year generation. One exceptional feature of the current outbreak is low damage to D. sibiricus caterpillars by diseases and parasites. Favorable weather conditions and a low number of natural entomopathogens contribute to the rapid spread of the pest in northern and eastern directions. This creates a high risk of mass outbreak of D. sibiricus in dark coniferous forests, since the area of nearby dark coniferous stands suitable in structure, climatic, and forest-growing conditions for the pest dispersal is more than 2.7 million ha. Pure cultures of the entomopathogenic fungus Beauveria bassiana were isolated from dead caterpillars of D. sibiricus. Multistage screening made it possible to select a promising strain for the creation of a long-acting bioinsecticide for the preventive treatment of forests. The main selection criteria are high virulence, high entomopathogenic activity at low temperatures (7–10°C), and the ability for solid-phase fermentation of plant waste.

This paper is concerned with the phytomass of herbaceous phytocenoses growing in anthropogenically impacted areas in the Middle Urals at different stages of succession along the heavy-metal pollution gradient. Cenoses of young soils of dumps have less resistance and higher sensitivity to changes in weather factors, in contrast to the phytocenoses of the deposits. It is shown by general regression models that the epiterranean and subterranean biomass of cenoses on technozems depends on Selyaninov’s hydrothermic coefficient for September and the amount of precipitation in October–November of the previous year and in January–May of the current year. The degree of this dependence for cenoses under research is determined by edaphic conditions that affect the species diversity and dominance structure.