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养分状况对泡桐针叶混交林土壤微生物群落的影响
Response of Soil Microbial Communities to Environmental Conditions in Paulownia and Coniferous Mixed Forests
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摘要: 以泡桐、马尾松、杉木纯林及泡桐针叶混交林为研究对象,采用底物诱导呼吸(SIR)和磷脂脂肪酸(PLFA)分析,比较肥沃棕壤和贫瘠砂姜黑土对土壤微生物功能与结构的影响。结果表明:林分类型对微生物的影响显著依赖于生境的养分状况。在贫瘠生境中,针叶纯林及泡桐针叶混交林均显著降低了微生物基础呼吸和生物量,提高了PLFA衍生的生理胁迫指标,其中杉木纯林的抑制效应最为突出;在肥沃生境中,各林分类型无显著差异。 泡桐纯林土壤微生物特异性呼吸(qO2)和PLFA衍生的胁迫指标在不同生境间波动较小,显示出较强的稳定性。土壤微生物活性与生物量随土壤深度增加而降低,林分类型和生境条件对土壤微生物影响的模式与强度在不同矿质土之间存在差异。微生物群落结构主要由土壤养分状况决定,林分类型对其有显著的调控作用。贫瘠生境中,针叶纯林及泡桐针叶混交林可能通过抑制微生物活性与生物量,削弱土壤微生物介导的关键生态功能;肥沃生境中,树种选择对这些微生物指标的影响相对有限。泡桐林下微生物对环境变化响应的相对稳定性可能与其持续的根系碳输入有关。Abstract: The regulation of soil microbial communities by tree species composition in afforestation is crucial, particularly in resource-limited environments. This study employed substrate-induced respiration (SIR) and phospholipid fatty acid (PLFA) analyses to compare the effects of pure stands of Paulownia spp., Pinus massoniana, Cunninghamia lanceolata, and mixed stands of Paulownia with these two coniferous species on soil microbial community function and structure under two contrasting nutrient conditions: relatively fertile brown soil and poor sandy ginger black soil. Results indicated that the impact of stand type on microorganisms was significantly dependent on habitat conditions. In the nutrient-poor habitat, compared to pure Paulownia stands, both pure conifer stands and their mixed stands with Paulownia significantly decreased microbial basal respiration and biomass, and increased physiological stress indicators, with pure C. lanceolata stands exhibiting the most pronounced inhibitory effect. In contrast, microbial specific respiration and stress indicators under pure Paulownia stands showed less fluctuation across different habitats. Soil depth was also a key factor, with microbial activity and biomass decreasing with depth, and the impact patterns of stand type and habitat varying across soil layers. Microbial community structure was predominantly driven by habitat type, although stand type also exerted significant regulatory effects (especially in the litter layer and topsoil), an independent effect подарки even after controlling for soil physicochemical covariates. This study reveals that in low-nutrient regions, inappropriate conifer planting may impair soil microbial-mediated ecological functions, whereas in high-nutrient environments, the influence of tree species selection is relatively limited. Root-derived carbon input is considered an important mechanism mãe microbial responses. The impact of artificial forest stand composition on soil microorganisms necessitates a comprehensive assessment considering site-specific resource availability and soil vertical differentiation.