高寒草甸土壤微生物功能多样性对氮肥添加的响应

采用Biolog-ECO生态板法研究了4个施N水平[0 g/m²（CK），10 g/m²（N₁₀），20 g/m²（N₂₀），30 g/m²（N₃₀）]下土壤理化性质和微生物功能多样性的变化规律。结果表明:中高水平氮肥添加显著增加了速效氮、速效磷含量和根土比，但降低了土壤含水量。施N肥0-10 cm土层平均颜色变化率降低，而10-20 cm土层则被提高，且N₂₀最大。施N肥后降低了0-10 cm土层土壤微生物Shannon-Wiener指数、Pielou指数和McIntosh指数，但10-20 cm土层则被提高。PCA分析表明，施N肥改变了土壤微生物代谢功能类型，糖类、氨基酸、酸类是土壤微生物主要利用的碳源类型。RDA分析表明，在0-10 cm土层，土壤含水量和全氮是影响土壤微生物功能多样性的主要因子，而10-20 cm土层主要受土壤含水量和速效磷的影响。综上，施N肥增加了土壤的有效养分含量，进而改变土壤微生物功能多样性、碳源利用能力和数量。

Responses of Soil Microbial Functional Diversity to Nitrogen Addition in an Alpine Meadow on Northwestern Plateau of Sichuan Province

Biolog-Eco microplate is used in the study to reveal the effects of N addition with four rates of 0 g/m² (CK), 10 g/m² (N₁₀), 20 g/m² (N₂₀), 30 g/m² (N₃₀) on soil chemical properties and microbial functional diversity. The results showed that the N₂₀ and N₃₀ significantly increased available phosphorus, available nitrogen and ratio of root to soil, but decreased soil moisture content (SMC). Average well color development (AWCD) value decreased in surface soil layer (0-10 cm), but AWCD increased in deep soil layer (10-20 cm), especially under the treatment of N₂₀ N fertilizer reduced the Shannon-Wiener index, Pielou index and McIntosh index in the surface layer (0-10 cm), but it was opposite to that in the deep soil layer (10-20 cm). The principal component analysis showed that N fertilizer changed the metabolic functional type of soil microorganism and that carbohydrates, amino acid and acids were the main carbon sources utilized by microorganism. Redundancy analysis indicated that soil microbial functional diversity was mainly influenced by total nitrogen and SMC in 0-10 cm soil layer, but in the deep soil layer it was significant affected by SMC and AN. In summary, the addition of N fertilizer increased soil available nutrients, so, soil microbial functional diversity, capacity and quantity of carbon sources utilization were altered.