Abstract Soil climate (soil moisture and temperature) affects many near-surface earth system processes and ecosystem functions. However, the challenge of acquiring reliable, high-resolution data has impeded the quantitative assessment of the spatial heterogeneity of soil climate at hillslope and catchment scales, namely, soil micro-climate. Here, we examined three years of continuous soil micro-climate data to identify patterns in relation to slope aspect, position, and curvature in a 7.9-ha forested catchment in Pennsylvania, U.S.A. Multi-depth (5 to 162 cm) soil micro-climate data were collected by a sensor network consisting of 33 sites that were distributed throughout the catchment. Results showed a high degree of variability in time and space that alternated between wet-cold seasons (DJFMAM) and dry-warm seasons (JJASON). Compared to dry-warm seasons, soil moisture was spatially more variable but temporally more stable in wet-cold seasons. Slope characteristics substantially mediated soil micro-climate distribution and variability, which were further influenced by the season and soil depth. With increasing soil depth, soil micro-climate became spatially more variable but more stable through time. The north (N)-facing aspect intensified the temporal variability of soil micro-climate more than the south (S)-facing aspect. Swales and the valley floor dampened soil temperature fluctuations relative to planar slopes and the ridges. The N-facing slopes were significantly colder than the S-facing slopes but only in winter. The differences in slope insolation, vegetation cover, soil properties, and hydrology were used to explain soil micro-climate patterns. This study demonstrates the potential of sensor networks to investigate soil micro-climate at scales that are challenging for either point-scale measurements or remote sensing. These findings provide an enhanced understanding of localized soil micro-climate pattern and variability in forested headwater catchments, which can aide modeling water and energy budgets of the Critical Zone in temperate, humid region.

中文翻译：

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森林流域中与坡向、位置和曲率相关的土壤微气候变化

摘要 土壤气候（土壤湿度和温度）影响许多近地表地球系统过程和生态系统功能。然而，获取可靠、高分辨率数据的挑战阻碍了山坡和流域尺度土壤气候空间异质性的定量评估，即土壤微气候。在这里，我们检查了三年的连续土壤微气候数据，以确定美国宾夕法尼亚州 7.9 公顷森林集水区的坡向、位置和曲率模式 多深度（5 至 162 厘米）土壤微气候数据由一个传感器网络收集，该网络由分布在整个集水区的 33 个站点组成。结果显示，湿冷季节 (DJFMAM) 和干暖季节 (JJASON) 交替出现的时间和空间高度可变。与干暖季相比，湿冷季土壤水分在空间上的变化更大，但在时间上更稳定。坡度特征在很大程度上介导了土壤微气候分布和变异性，并进一步受到季节和土壤深度的影响。随着土壤深度的增加，土壤微气候在空间上变得更加可变，但随着时间的推移更加稳定。北（N）向比南（S）向加剧了土壤微气候的时间变化。洼地和谷底抑制了相对于平面斜坡和山脊的土壤温度波动。面向 N 的斜坡比面向 S 的斜坡明显更冷，但仅在冬季。坡度日照、植被覆盖、土壤性质和水文的差异被用来解释土壤微气候模式。这项研究展示了传感器网络在对点尺度测量或遥感具有挑战性的尺度上研究土壤微气候的潜力。这些发现增强了对森林源头集水区局部土壤微气候模式和变异性的理解，这有助于模拟温带、潮湿地区关键区域的水和能量收支。