【摘要】 为探究刺槐人工林根际和非根际土壤微生物元素利用效率的季节差异及其影响因素，在黄土高原选取3个季节(春季、夏季、秋季)人工林根际和非根际土壤为研究对象，测定土壤理化性质、微生物生物量和酶活性等指标，计算化学计量失衡、矢量特征及元素利用效率。结果表明，季节动态显著影响化学计量失衡，根际和非根际C∶N失衡在季节上均表现为先增加后降低的趋势，而C∶P和N∶P失衡则相反。矢量长度和矢量角度的变化表明根际与非根际土壤微生物均在夏季受到较强的碳、氮限制，而在春、秋季受到较强的磷限制。季节动态对微生物元素利用效率有显著影响，其中碳利用效率在夏季最低，而氮、磷利用效率在夏季最高。偏最小二乘路径模型结果表明，根际和非根际土壤微生物均通过矢量特征和胞外酶活性间接地影响元素利用效率，而非根际土壤微生物化学计量失衡对元素利用效率有直接影响。研究结果有助于深入理解人工林根际和非根际土壤微生物的养分利用机制，为生态脆弱地区的人工林管理提供理论依据。更多还原

【Abstract】 To investigate the seasonal dynamics and influencing factors of soil stoichiometric characteristics and microbial elements use efficiency in the rhizosphere and bulk soils, the rhizosphere and bulk soils of Robinia pseudoacacia plantations in three seasons(Spring, Summer, and Autumn) were selected as the study objects on the Loess Plateau. Soil physicochemical properties, microbial biomass, and enzyme activity were determined, and stoichiometric imbalance, vector characteristics, and element use efficiency were calculated. Combined with Partial least squares path model analysis of various related environmental factors, this study investigates the seasonal variation mechanism of microbial element utilization efficiency in rhizosphere and bulk soils. The results showed that the seasonal dynamics significantly influenced stoichiometric imbalance, with both rhizosphere and bulk soils C∶N imbalance showing an increase trend followed by decrease across seasons, reaching its maximum value in summer(0.91, 3.22). While C∶P and N∶P imbalances exhibited the opposite pattern. The VL of rhizosphere and bulk soils are highest in summer, while VA are greater than 45° in spring and autumn, and less than 45° in summer. Changes in VL and VA indicated that soil microorganisms in both rhizosphere and bulk soils experienced stronger carbon and nitrogen limitations in summer, and stronger phosphorus limitation in spring and autumn. The seasonal dynamics have a significant impact on the utilization efficiency of microbial elements, with carbon utilization efficiency being the lowest in summer, with an average of about 0.33, and nitrogen and phosphorus utilization efficiency being the highest in summer. This indicates that rhizosphere soils microorganisms have a stronger contribution to carbon fixation in spring and autumn, while bulk soils microorganisms have a stronger contribution to nitrogen and phosphorus fixation in summer. The results of the partial least squares path model indicate that the factors affecting soil element utilization efficiency include stoichiometric imbalance and resource limitations. Both rhizosphere and bulk soils microorganisms indirectly affect element utilization efficiency through vector features and extracellular enzyme activities, while stoichiometric imbalance in bulk soils had direct effect on microbial elemental use efficiency. Soil microorganisms adapt to the environment by adjusting enzyme investments in different restricted nutrients, in order to alleviate resource limitations caused by stoichiometric imbalances and thus affect seasonal differences in element utilization efficiency. The results contribute to an in-depth understanding of the nutrient utilization mechanisms of rhizosphere and bulk soils microorganisms in plantation forests, and provide a theoretical basis for the management of plantation forests in ecologically fragile areas.更多还原