Changes in the Temperature Regime of Soils under Larch and Pine Forests in Central Yakutia

Recent climate warming has become one of the most pressing environmental problems, posing a significant threat to ecosystems, economies, and societies worldwide. In 2021, a year recognized as abnormally hot and dry one, great landscape wildfires on the Lena-Vilyuy interfluve destroyed approximately 1.4 million ha of forest, which led to significant changes in the biotope structure at all levels. These changes included noticeable transformation of physicochemical properties and hydrothermal regimes of soils, which exert long-term effect on the ecosystems. As a result of comprehensive studies on monitoring sites of pine and larch forests on ancient alluvial loamy-sandy deposits after large forest fires in Central Yakutia performed using classical soil science methods combined with geophysical techniques, the appearance of suprapermafrost taliks more than 20 m deep was registered as well as the absence of connection between the seasonally frozen layer and the permafrost massif in the cold season. For the first time it was shown that in the localities with this phenomenon manifestation, the permafrost type of soil temperature regime has turned to the long-term seasonally freezing type.