N deposition is one of the important factors affecting the global change. Research shows that the N deposition will increase continually in the coming decades. By simulation of N deposition experiment, in lab or field, Scientists have got some knowledge on changes in nutrient cycling of terrestrial ecosystem, plant productivity, plant diversity and soil microbe biomass under increased N deposition. 

Recent years, the development of technology and equipment in DNA sequencing of microbes led to the estimation of soil microbial diversity become more efficient and economic. This provides the possibility of research in the effect of N deposition on microbial diversity on global scale. 

Research has shown the effect of N deposition on plant productivity is closely related to the effect on plant diversity. The next question is whether the effect of N deposition on microbial biomass is related to the effect on microbial diversity. 

To answer this question, Dr. WANG Chao and coworkers from Institute of Applied Ecology of the Chinese Academy of Sciences collected and analyzed 198 published soil microbial diversity data from simulation experiments all over the world, including 171 Shannon indexes and 102 Chao1 indexes to investigate the relationship between changes in bacteria and fungus diversity and changes in microbial biomass.  

The results showed that N addition significantly reduced Shannon and Chao1 indexes of bacteria and fungus while significantly reduced the relative diversity of AcidobacteriaandNitrospirae.  

Under N addition, the reduction of microbial mass is significantly related to the reduction in microbial diversity indicating that it is soil nutrition but not pH that is main factor affecting changes in microbial diversity. 

The work revealed the basic reason that increase in N deposition leads to the reduction in biomass of microbes and provides strong support to understanding in the effect of N deposition on the nutrient cycling among terrestrial plant-soil-microbes and ecosystem functions.  

The results were published on Soil Biology and Biochemistry, entitled as Decreasing Soil Microbial Diversity is Associated with Decreasing Microbial Biomass under Nitrogen Addition. 

The work was supported the National Key R & D project, NNSFC, Frontier Science Key Project of CAS and Youth Innovation Promotion Association of the Chinese Academy of Sciences.