Soil moisture (SM) is a key factor that determines the stability and functioning of desert ecological systems, but has been rarely studied due to the difficulty of sampling. The characterization of the temporal stability of soil moisture (SM TS) and its statistical parameters is much needed. To identify suitable locations to estimate SM status for the study area, and obtain greater insights into the SM TS of the Horqin Sand Land, SM was measured in a fixed dune (FD) over a depth profile of 0–1 m and on 14 occasions between May and July 2021. These data were combined with soil property and precipitation measurements to assess the SM TS and determine the optimal locations that could represent the mean SM of the area. Results indicated that (1) the mean SM of FD varied from 1.98% to 6.73%, with minimal spatial variation (mean standard deviation (STD) < 3%; mean coefficient of variation (CV) ranging between 42% and 56%). (2) SM continually decreased over time until considerable precipitation occurred. Temporal dynamics decreased with increasing soil depth. Further, only larger precipitation events (> 20 mm) led to significant SM increases. In deeper soil layers (> 60 cm), the SM response exhibited a lag. (3) The relationship between STD and mean SM indicated that SM becomes more variable under wetter conditions, such that SM increases were associated with CV increases in this region. (4) The Spearman’s rank correlation coefficient (RS) values between different sampling dates indicated that most of the relationships were significant (p < 0.05), especially for soils in the 60–100 cm layer. (5) The mean values of mean relative differences (MRD) were smaller for soils < 40 cm and the mean corresponding standard deviation of MRD (SDRD) values were smaller for soils < 60 cm, indicating that SM tended to be more stable in deeper soil layers. (6) Linear regression analyses between the estimated means obtained from the identified locations and the actual field means led to the identification of the best representative SM locations for the 0–20, 20–40, 40–60, 60–80, and 80–100 cm layers at locations 8, 16, 8, 11, and 6, respectively. (7) The accumulated temporal stability index (ITS) of SM for different soil layers suggested that the 12th location (with a minimum ITS value) was the most representative location to approximate the mean SM of different soil layers in the FD. However, linear regression analyses of the SM between the actual field mean and that of the 12th representative location revealed a satisfactory fit only for soil layers above 40 cm. This study contributes to our understanding of SM patterns in arid environments, which have important implications for ground sampling design and hydro-logic modeling.

土壤水分（ SM）是决定荒漠生态系统稳定性和功能的关键因素，但由于采样困难，研究较少。土壤水分的时间稳定性（SM TS）及其统计参数的表征是非常需要的。为了确定合适的位置来估计研究区的 SM 状态，并更好地了解科尔沁沙地的 SM TS，在 0-1 m 深度剖面的固定沙丘 (FD) 中测量了 14 次 SM。 2021 年 5 月至 7 月期间。这些数据与土壤特性和降水测量相结合，以评估 SM TS 并确定可以代表该地区平均 SM 的最佳位置。结果表明：(1) FD 的平均 SM 变化范围为 1.98% 至 6.73%，空间变异最小（平均标准差 (STD) < 3%；平均变异系数 (CV) 范围在 42% 至 56% 之间）。 (2) SM随着时间的推移不断减少，直至出现大量降水。时间动态随着土壤深度的增加而降低。此外，只有较大的降水事件（> 20 毫米）才会导致 SM 显着增加。在较深的土层（> 60 cm）中，SM 响应表现出滞后。 (3) STD 和平均 SM 之间的关系表明，在潮湿条件下，SM 变得更加可变，因此 SM 增加与该区域的 CV 增加相关。 (4)不同采样日期之间的Spearman等级相关系数(RS)值表明大多数相关性是显着的( p  <0.05)，特别是对于60-100cm层的土壤。 (5) < 40 cm土壤的平均相对差值(MRD)平均值较小，< 60 cm土壤的MRD平均值相应标准差(SDRD)值较小，表明SM在更深的土壤中趋于稳定。土壤层。 (6) 从确定位置获得的估计平均值与实际现场平均值之间的线性回归分析确定了 0-20、20-40、40-60、60-80 和 80 的最佳代表性 SM 位置。 – 100 厘米层分别位于位置 8、16、8、11 和 6。 （7）不同土层SM的累积时间稳定性指数（ITS）表明，第12个位置（ITS值最小）是最有代表性的位置，可以近似FD中不同土层的平均SM。然而，实际田间平均值与第 12 个代表位置的 SM 之间的线性回归分析表明，仅对于 40 厘米以上的土层而言，拟合效果令人满意。这项研究有助于我们理解干旱环境中的 SM 模式，这对地面采样设计和水文建模具有重要意义。