Postfire Evolution of Forest Ecosystems on Sandy Terraces in the Southeastern Baikal Region

In the Baikal region, warming under conditions of climate continentality is accompanied by an increase in the area of forest fires and the risk that postpyrogenic ecosystems will not return as forests. A study of pine forests on sand sediments in the southeastern Baikal region showed that the regional ecosystems damaged by fire develop in different directions depending on the type of fire and local conditions. After a ground fire, an adult forest stand is preserved and stable signs of pyrogenesis in the soil are developed in the form of charred epipedons. Under these conditions, sparse-grass and dead-cover open stands are formed with almost no signs of renewed young growth and shrubs. The coal effect causes a decrease in soil acidity, an increase in the content of exchangeable calcium, the formation of humus of humate composition, and base unsaturation. It is proposed to identify the soils with coal epipedons at the level of subtype as psammosoils humic postpyrogenic. After a top fire, the plant cover and the soil cover are completely destroyed; the ecosystem begins its development from scratch. Forest renewal in lowlands and on the slopes of shadow and leeward expositions occurs actively in a natural way, as well as against the background of reforestation. During the postfire period, psammosoil humic soil of a weakly developed order is formed under the young forest. On the slopes of solar upwind expositions, unforested deflation zones with no signs of soil formation are formed despite the actions taken to restore the forest stand. Remote sensing methods made it possible to ascertain that, over 15 years of postfire development, despite the reforestation, the area of unforested deflation zones has increased 11-fold when compared to the prefire period. It is recommended to introduce forest-stand restoration in the form of loosening the charred soil on the territories damaged by ground fires, as well as the repeated execution of forest planting works in the deflated areas considering the protection of the forest edges from wind into a set of measures to restore forest ecosystems after wildfires.