Effects of winter snowpack and nitrogen addition on the soil microbial community in a temperate forest in northeastern China

Nitrogen (N) deposition and change of snowpack are two critical factors for soil microbial community in temperate forests. The responses of soil microbial community composition and diversity to snowpack changes and N deposition are rarely investigated in winter. Therefore, we conducted an experiment to detect the microbial responses to the different snowpack depths (0 cm and 40 cm) and N addition (0 g N m−2 yr−1 and 5 g N m−2 yr−1 for four years) in a cold temperate forest in northeastern China in winter. The results indicated that decreased snowpack and increased N caused the significant changes in the soil microbial community composition in winter. The N addition significantly decreased bacterial abundance and diversity, which may be caused by decrease of pH and increase of inorganic N concentration under N addition. The decreased temperature associated with the removal of snowpack was considered to be able to trigger the variability in the soil fungal and bacterial community composition and diversity. The reduction in snowpack also decreased the soil respiration rate and the microbial biomass carbon (C) and N. However, the inhibition effect of N addition on soil respiration only occurred in the no snowpack treatments during the winter in our study, which indicates that N addition might change the activity of cold-tolerant microorganisms. In general, increased N deposition and reduced snowpack might potentially affect ecosystem functioning and terrestrial ecosystem C cycling in temperate forests under global change scenarios.