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Soil erosion resistance is influenced by intrinsic soil properties and multiple external factors. This study investigated the effect of tea planting age on soil resistance to flowing water erosion (reflected by rill erodibility (K r ) and critical shear stress (τ c )) in Three Gorges Reservoir Area. One slope farmland (as the control) and five tea plantations cultivated for 3 to 34 years were selected for sampling sites. The results indicated that bulk density (BD), soil cohesion (Coh), water stable aggregate (WSA), mean weight diameter (MWD), soil organic carbon (SOC), litter density (LD), and root mass density (RMD) increased generally with tea planting age. Compared to the control, K r of tea plantations reduced by 71.1%-85.3%. The temporal variation in soil erosion resistance was controlled greatly by the variations in most near-surface characteristics. K r decreased with WSA, Coh, LD, RMD, and SOC following a power function (P < 0.01); τ c increased with MWD, LD, RMD, and SOC as an exponential function, with BD a power function, and Coh a logarithmic function (P < 0.01). In this study, K r could be simulated well by WSA and LD with a power function, and τ c could be simulated well by MWD and RMD with an exponential function.

As an important component of nutrients turnover and the food chain, soil microbes play vital roles in driving and regulating terrestrial ecosystem processes and key elements cycling like carbon (C), nitrogen (N), and phosphorus (P) (Cui et al. 2018. Microbial biomass carbon (MBC), nitrogen (MBN) and phosphorus (MBP) are crucial constituents of the soil microbial biomass (SMB), and their proportions in corresponding soil elements, namely soil microbial quotient (SMQ, expressed as qMBC, qMBN, and qMBP for microbial quotient C, N, and P, respectively), are the key indicators of soil quality and represent how efficiently soil nutrients being used by microbes (Chen et al. 2021. SMQ can be considered as an integrative measure of edaphic properties, soil biodiversity, substrate quality and quantity that reflects soil microbe stress adaptability and biomass productivity (Sinsabaugh et al. 2016, Malik et al. 2018. SMQ thus can serve as an early alert warning for microbial status during ecosystem succession induced by environmental stresses or human disturbance (Yan