Soil property changes following a thaw-induced mass movement event in the permafrost region of the Qinghai–Tibetan Plateau

Thaw-induced mass movements are common geomorphological phenomena induced by permafrost degradation, which has profound implications for soil health and ecosystem stability. Despite significant changes in soil properties caused by thaw-induced mass movements, a thorough understanding and quantitative assessments of this phenomenon is relatively scarce. This study systematically quantified the effects of thaw-induced mass movements on various soil parameters by analyzing soil structural, hydraulic, chemical, and thermal properties at different locations of a typical thaw-induced mass movements in the permafrost region of the Qinghai–Tibetan Plateau. This study also investigated the changes in soil texture, water content, pH, organic carbon content and erodibility at different soil depths. Our findings showed that soil particles became finer and bulk density increased downslope. Concurrently, soil aggregate stability and erodibility also increased downslope. Soil water content and organic matter content both displayed a consistent downslope decrease. At the toe of the mass movement, soil hydraulic properties were significantly lower, with the lowest water holding capacity, along with reduced saturated hydraulic conductivity and field water capacity (i.e., 57.89% and 54.03% of the control, respectively). In addition, the pattern and rate of heat transfer were directly affected by the changes in soil parameters. As soil water content decreased, soil thermal conductivity and volumetric heat capacity showed an exponential and linear decrease, respectively. This study provides important data for understanding permafrost degradation and soil ecosystem response through quantitative analysis, and confirms the effects of thaw-induced mass movements on regional soil parameters.