长期单作对枸杞园不同土层土壤微生物代谢活性和多样性的影响

土壤微生物群落多样性及其活性对维持农田土壤生态系统稳定和功能至关重要。前期研究表明，长期单作可导致枸杞园土壤微生物多样性降低和群落结构变异，但对其如何影响土壤微生物代谢活性尚不明确。为研究微生物代谢活性对长期单作的响应，利用Biolog Eco平板分析了枸杞园表层（0~20 cm）和亚表层（20~40 cm）土壤微生物底物利用谱（CLPP）的年代变化规律。结合土壤酶活性和理化性质测定和分析，探索了土壤微生物底物利用谱变化的驱动因子。结果表明，长期单作促进了枸杞园表层土壤微生物群落的代谢活性（P<0.05），但不影响亚表层土壤微生物的代谢活性和Shannon指数。随种植年限增加，表层土壤微生物对吐温80和衣康酸的代谢活性增加，而亚表层土壤微生物对D-葡萄氨酸和苯乙基胺的利用显著降低（P<0.05）。对不同碳源类型的分析发现，长期单作抑制了枸杞园表层和亚表层土壤微生物对多聚物的利用能力（P<0.05），说明土壤微生物对复杂有机物的降解能力可能受到干扰。变差分解分析表明，土壤理化性质和真菌丰度是驱动枸杞园土壤微生物代谢多样性变异的主要因子。这些结果表明长期单作干扰了枸杞园，尤其是亚表层土壤微生物的代谢活性，影响了其对复杂有机物的分解过程。在长期单作下，枸杞园亚表层土壤的植物-土壤负反馈作用可能更加严重，应受到更多关注。

Effects of long-term monocropping on soil microbial metabolic activity and diversity in topsoil and subsoil horizons of Lycium barbarum fields

The diversity and activity of soil microbial communities are essential for maintenance of the stability and function of the soil ecosystem. However， long-term monocropping of Lycium barbarum has caused biodiversity loss and alteration of soil microbial community composition. It is still unclear how such management affects soil microbial metabolic activity. This research explored the impacts of long-term monocropping on soil microbial metabolic activity in L. barbarum fields. We investigated the variation of microbial community-level physiological profiles （CLPP） in the topsoil （0-20 cm） and subsoil （20-40 cm） horizons of L. barbarum fields using Biolog EcoPlate methodology. Soil enzyme activities and abiotic properties were measured to explore the factors driving variation in CLPP. It was found that L.barbarum monocropping promoted the microbial metabolic activity of topsoil （P<0.05）， but did not affect that of the subsoil nor the metabolic diversity index of either soil horizon. With increase in stand age， the utilization rates of Tween 80 and itaconic acid increased in topsoil， while those of D-glucosaminic acid and phenylethylamine decreased significantly in subsoil （P<0.05）. The utilization of polymers significantly decreased with the increase in stand age in both soil depths （P<0.05）， indicating that long-term monocropping affects the ability of soil microorganisms to degrade complex organic matter. Variance partitioning analysis further suggested that soil abiotic properties and fungal abundance were the major factors driving the variation in soil microbial metabolic diversity in L. barbarum fields. The data show that long-term monocropping disturbed the metabolic activity and the decomposition rates of complex soil organic matter， particularly in the subsoil. We propose that the subsoil quality of L. barbarum fields should be monitored and supervised under monocropping.