Abstract: In order to understand the response of soil microbial diversity to nitrogen deposition in alpine wetland under the background of nitrogen deposition, four levels (0, 2, 5 and 10 g/m2) were used to simulate nitrogen addition. The diversity and community structure of soil bacteria and fungi were analyzed by high throughput technique. The results showed that the dominant flora of bacteria were Acidobacteria and Actinobacteria of Proteobacteria and that of fungi were Ascomycota Basidiomycota and Mortierellomycota. Nitrogen treatment significantly changed the relative abundance of bacteria and fungi. NMDS analysis showed that the community structure of soil bacteria and fungi changed significantly under nitrogen treatment (P＜0.01). Cluster analysis showed that the difference of soil microbial species composition increased with the increase of nitrogen application concentration. With the change of nitrogen application concentration, the diversity index of microorganisms changed significantly in the 015 cm soil layer, but not significantly in the 1530 cm soil layer. The response mechanism of bacteria and fungi to N deposition was different, the bacterial diversity showed an upward trend, while the fungal diversity showed a downward trend. It can be seen that N deposition has an impact on soil microbial structure and a certain difference on bacterial and fungal diversity, which can provide a basis for wetland management under the background of N deposition.

Key words: alpine wetland, nitrogen deposition, soil microorganism, diversity, community structure