Abstract: Effects of six continuous years nitrogen deposition on soil fungi community structure in Stipa Baicalensis steppe were investigated by using high-throughput sequencing technology. The experiment included eight manipulative treatments:(0,15,30,50,100,150,200 and 300 kg N·hm^-2·a^-1). Soil samples were separately collected from the 0~10 cm and 10~20 cm soil layer. The results showed that nitrogen deposition significantly affected the structure of fungi community. the relative abundance of fungi in the phyla,class and genus level were significantly different at the 0~10 cm and 10~20 cm soil layer of nitrogen deposition treatment. The response of soil fungal community to nitrogen deposition at the 0~10 cm soil layer and 10~20 cm soil layer was significantly different,and there was obvious soil gradient effect. Canonical correspondence analysis (CCA) showed that soil pH,soil total organic C,NO₃^--N and available P were key environmental factors leading to the shift in the soil fungal community composition. In conclusion,nitrogen deposition changed the soil chemical properties,which drove the change of soil microbial communities and soil fungal communities.

Key words: Nitrogen deposition, Stipa Baicalensis steppe, Soil fungi, Community structure, Pyrosequencing technique

摘要： 以贝加尔针茅草原为研究对象，采用高通量测序技术，研究连续6年模拟8个氮沉降水平（0，15，30，50，100，150，200，300 kg N·hm^-2·a^-1）对贝加尔针茅草原0~10 cm、10~20 cm土层土壤真菌群落结构的影响。结果表明，氮沉降显著影响真菌群落结构，0~10 cm土层与10~20 cm土层各氮沉降处理相对丰度在门、纲、属水平上均存在明显差异；且0~10 cm土层与10~20 cm土层土壤真菌群落对氮沉降的响应存在明显差异，存在明显的土层梯度效应。典范对应分析表明，土壤pH、有机碳、硝态氮和速效磷含量是影响贝加尔针茅草原土壤真菌群落结构变化重要因素。以上结果表明，氮沉降通过改变草原土壤的化学性质，影响了土壤真菌群落结构。

关键词: 氮沉降, 贝加尔针茅草原, 土壤真菌, 群落结构, 高通量测序