Characteristics and controlling factors of soil micro-climate in a subtropical re-vegetation catchment: Insights from continuous moisture and temperature observations

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  • Background and aimsGlobal increases in vegetation greenness are largely attributed to ecological restoration efforts. Soil micro-climate (moisture and temperature) serves as the foundation for vegetation recovery and constitutes a critical component of ecosystem services. However, in subtropical humid mountainous regions with complex terrain, the spatial patterns and driving factors of soil micro-climate remain poorly understood.MethodsFrom 2020 to 2021, high-resolution (5-min intervals) soil moisture and temperature data were continuously collected to characterize soil micro-climate across four topographic positions (lower valley, upper valley, south-facing slope, and north-facing slope) in a re-vegetated catchment in China's Three Gorges Reservoir Area.ResultsSoil moisture exhibited strong spatial heterogeneity, being higher in valley than slopes. The lower valley had the highest soil moisture content (0.36 cm3 cm(-)3), while north-facing slope had the lowest (0.26 cm3 cm(-)3). Soil temperature within the profile varied seasonally, increasing by 5.0 to 9.2 degrees C during the rainy season. Additionally, seasonal fluctuations of temperature were smaller in deeper soil layers, highlighting the thermal buffering capacity of subsurface soils. Mantel test revealed that slope position exerted its influence on the soil micro-climate through differences in vegetation canopy closure, root depth and soil texture. During the rainy season, air temperature (41.1% contribution) and relative humidity (46.1% contribution) were the primary factors influencing soil micro-climate. In contrast, during the non-rainy season, air temperature became the most significant factor, with an average contribution exceeding 55%.ConclusionsOur findings highlight the spatiotemporal variability of soil micro-climate and its key controlling factors in subtropical mountainous ecosystems. These insights can provide guidance for developing more effective and targeted vegetation restoration strategies, including the selection of appropriate species and the positioning of restoration sites. Moreover, further validation is needed to refine these applications for practical use.