The soil cover patterns in the subtaiga landscapes on the northern spurs of the Tsagan-Daban Ridge in the Selenga Mountains have been studied. Gray-humus lithozems and bedrock outcrops are typical of the steep south-facing slopes under herbaceous pine forests. Soddy iron-illuvial podburs are formed under forest vegetation on gentle slopes of northern and western aspects with a thick mantle of loose colluvial deposits. Dark-humus metamorphic soils occur on the slopes of western and northwestern aspects below 700 m a.s.l. under secondary forb-grassy communities that replaced the initial herbaceous pine forests. Windblown hollows (yardangs) are occupied by humus psammozems under steppe pine forests. The morphological and physicochemical characteristics of these soils are discussed in the paper.

The basis for assessing the stability of geosystems to changes in external heat cycle conditions is the calculation method. It is shown that permafrost soils are characterized by increased values of annual heat cycle Q_Y ≥ 300 MJ/m², i.e., half-sum of heat arrival and flow rate per year. This is due to the high heat consumption for melting soils (Q_Ph = 0.7–0.8 Q_Y) and warming them in the negative temperature range (Q_F). The heat cycle in frozen soil (Q_F) always has more heat cycle than in the thawed soil (Q_H). The condition Q_F > Q_H means the dominance of processes occurring at negative temperature, and the difference Q_{F −} Q_H is a quantitative assessment of the energy stability of soils to changes in heat exchange conditions on the surface.

A new view on the genesis and properties of soils in landscapes of the taiga–steppe ecotone in the Selenga Mountains of western Transbaikalia is suggested with due account for the modern...

This paper examines fire-induced transformations of the main ecosystem components in steppificated pine forests that grow in the mid-mountain part of the Selenga River basin (Western Transbaikalia). It has been established that medium-intensity ground fires that occur most frequently in the region transform the living ground cover and alter the composition and properties of forest litter, as well as the morphological, physicochemical, and hydrothermic properties of soils. The changes in the species diversity, projective cover, and phytomass of the herbaceous vegetation observed in the course of the postfire dynamics are minor. In contrast, the parameters of the moss–lichen cover, forest litter, and soils undergo significant transformations. In recently burned areas, mosses and lichens are completely destroyed; while the forest litter is thin, consists primarily of recently fallen needles and branches, and its reserves are low. Immediately after a fire, the moisture content in the upper pyrogenic soil horizons decreases, while the soil temperature increases. The following pyrogenic signs are observed in the humus-accumulative horizons of the soil profile: very dark coloration of organic matter combustion products, alkalization, and increased concentrations of calcium and carbon cations; concurrently, an increase in content of oxalate-soluble iron is observed in the illuvial horizons. At 5 or more years after a ground fire, a number of positive changes are observed, including an increase in forest litter thickness, formation of the moss–lichen cover, gradual changes in the chemical properties, a decrease in soil temperature, and some stabilization of field moisture parameters in the upper part of the soil profile. It has been established that the pyrogenic transformations of the forest litter, moss–lichen cover, and soils adversely affect the postfire restoration of the forest vegetation and regeneration of pine stands in areas affected by medium-intensity ground fires.

Проблема генезиса лессов, как одного из самых специфичных образований четвертичного периода, является объектом многолетних научных дискуссий. Дискуссионность и недостаточная изученность лессовой проблемы и формирующиеся на них современные почвы определило цель работы – исследование особенностей генезиса почв на лессовых породах на примере северного макросклона хр. Цаган-Дабан Западного Забайкалья. Использовались методы: ключевых участков, сравнительно-географический, профильно-генетический. Физико-химические свойства почв определялись общепринятыми методами. Гранулометрический состав определялся пипеточным методом. Типы почв определялись согласно “Классификации и диагностики почв России” и “Полевому определителю”. Выявлено, что дерново-подзолистые почвы формируются на водоразделе южнотаежного высотно-поясного комплекса (ВПК) на типичных лессах; буроземы темные – в верхних частях склонов подтаежно-лесостепного ВПК на типичных лессах; серогумусовые метаморфизованные – в средних частях склонов подтаежно-лесостепного ВПК на лессовидных отложениях; темногумусовые остаточно-карбонатные и агроземы темные – на делювиальных шлейфах лесостепного ВПК на типичных лессах; каштановые почвы и агроземы текстурно-карбонатные – в днищах котловин сухостепного ВПК на лессовидных отложениях. В целом, для почв на лессовых породах наблюдается увеличение количества илистых фракций на более высоких отметках, что объясняется усилением процессов выветривания в горах, где господствует более гумидный микроклимат. Рассмотренные лессовые породы и формирующиеся на них современные почвы северного макросклона хр. Цаган-Дабан Западного Забайкалья являются образованиями сингенетического аридного педогенеза.

A study is made of the northern spurs of the Tsagan-Daban Range in the Transbaikalia which are represented by Central-Asian and North-Asian taiga geosystems. The investigations of landscape structure were made in two key areas characterized by an alternation of mountain ranges and intermontane depressions (creek valleys).