Calculated geocryological characteristics of interlases after forest fires in Central Yakutia

Abstract

In recent years, forest fires have demonstrated an increasing trend in Yakutia, associated with modern global warming and extensive activation of cryogenic processes. In Central Yakutia, an ice complex is widespread, confined to the inter-alas type of terrain. Thawing of the ice component of the soils leads to the development of thermokarst, which is observed in disturbed treeless areas. The general climatic conditions, lithological and geocryological characteristics of the areas for which numerical modeling of the thermal state of soils was performed are described. The thermal state of inter-alas soils in 8 areas after forest fires was modeled during vegetation restoration, taking into account the current trend of increasing air temperature by 0.02о /year. The models were compiled for key periods of change in surface conditions and vegetation: 3, 8, 10 and 25 years after forest fires. It was revealed that in the Pokrovsk, Borogontsy and Berdigestyakh areas, it is possible to reach the depth of thawing of the ice horizon, which is due to high mean annual air temperatures and the spread of sandy loam in the upper part of deposits. And if the vegetation is not restored within the first three years, then presumably cryogenic processes will occur in these areas. In other areas, according to the modeling results, thawing does not reach the ice complex; gradual self-restoration of vegetation should bring geocryological conditions to their original state within 20-25 years. Soil temperatures are expected to rise, which is related to the current general warming of the climate. If the warming trend continues, thawing and soil temperature increases will be more significant and noticeable.