Freeze-thaw cycles (FTCs) extensively and intensely occur in cold regions, significantly affecting soil properties. However, quantifying the impacts of FTCs at different initial conditions on soil properties is challenging due to the complex interactive responses. In this study, porosity, bulk density, field capacity and saturated hydraulic conductivity (Ks) were measured to evaluate the responses of soil to FTCs. Eight FTCs (0, 1, 3, 5, 7, 10, 15 and 20 cycles), five initial soil mass water contents (10, 20, 30, 40 and 45 %), four eroded soils (original, degraded, deposited and parent), two initial bulk densities (1.2 and 1.3 g cm−3) and two freezing temperatures (−10 and −15 ℃) were employed to quantify the impacts of FTCs on physical properties. Results showed that repeated FTCs had a cumulative effect on soil physical properties, which generally entered a steady state after 10–15 FTCs. Changes in soil physical properties were highlighted after the initial 1–3 FTCs, and the effects of FTCs on physical properties diminished when the soil water content was below 20 %. Soil physical properties with different initial conditions responded differently to FTCs. Porosity increased with FTCs in increments ranging from about 0.2 to 8.7 %; however, the opposite result was observed when the initial soil water content exceeded 30 %. The bulk density decreased by 1.1–3.7 % with increasing FTCs, whereas the bulk density of the soils with high water content and severe soil erosion increased by 0.2–7.5 %. Compared to the initial state, the field capacity decreased by 0.1–15.3 % after 20 FTCs; however, the field capacity increased by 10.4 % under high bulk density. The Ks increased by 21.8–249.5 % with the increase of FTCs, whereas the Ks of the soils with 40 % and 45 % water content decreased by 28.7 % and 90.4 %, respectively. Overall, soil physical properties responded more strongly to FTCs at high water content, severe soil erosion, moderate bulk density and low freezing temperature. In comparison, the degree of soil erosion was the most critical factor influencing soil physical properties. These findings can help to improve the understanding of soil dynamic processes and provide new insight into mechanisms of erosion caused by seasonal FTCs.

中文翻译：

---

模拟条件下典型 Mollisol 的物理性质对冻融循环的响应


冻融循环 （FTC） 广泛而强烈地发生在寒冷地区，严重影响土壤特性。然而，由于复杂的交互响应，量化 FTC 在不同初始条件下对土壤特性的影响具有挑战性。在这项研究中，测量了孔隙度、容积密度、田间容量和饱和水力传导率 （Ks），以评估土壤对 FTC 的响应。采用 8 个 FTC（0、1、3、5、7、10、15 和 20 个循环）、5 个初始土壤质量含水量（10、20、30、40 和 45%）、4 个侵蚀土壤（原始、退化、沉积和母质）、2 个初始体积密度（1.2 和 1.3 g cm-3）和两个冻结温度（-10 和 -15 °C）来量化 FTC 对物理性能的影响。结果表明，重复的 FTC 对土壤物理性质具有累积影响，土壤物理性质通常在 10–15 次 FTC 后进入稳态，在最初的 1–3 次 FTC 后土壤物理性质的变化突出，当土壤含水量低于 20 % 时，FTC 对物理性质的影响减弱。不同初始条件的土壤物理性质对 FTCs 的响应不同，孔隙度随 FTC 的增加而增加，增量范围约为 0.2 至 8.7 %;然而，当初始土壤含水量超过 30 % 时，观察到相反的结果。随着 FTC 的增加，容重降低了 1.1-3.7%，而含水量高、土壤侵蚀严重的土壤的容重增加了 0.2-7.5%。与初始状态相比，20 次 FTC 后场容量下降了 0.1-15.3 %;然而，在高堆积密度下，田间容量增加了 10.4%。K 增加了 21.8-249。5 %，而含水量为 40 % 和 45 % 的土壤的 Ks 分别下降了 28.7 % 和 90.4 %。总体而言，在高含水量、严重土壤侵蚀、中等容重和低冻结温度下，土壤物理性质对 FTC 的响应更强。相比之下，土壤侵蚀程度是影响土壤物理性质的最关键因素。这些发现有助于提高对土壤动力学过程的理解，并为季节性 FTC 引起的侵蚀机制提供新的见解。