LAUSR

Forest soil microbial activity is an important aspect of soil properties, and the number of the three kinds of microorganisms (bacteria, fungi, and actinomycetes) is an important indicator of the level of soil microbial activity. To understand the effects of increasing nitrogen deposition on soil microorganisms, an in situ experiment was conducted in a natural evergreen broadleaf forest in Ya′an City, Sichuan Province. We conducted the field experiment between November 2013 and December 2014. Four levels of nitrogen deposition were set: control (CK 0 kg N hm a), low nitrogen (L 50 kg N hm a ), medium nitrogen (M 150 kg N hm a ), and high nitrogen (H 300 kg N hm a ). The results indicated that the number of bacteria, fungi, and actinomycetes in the 0—10 cm soil layer was significantly greater than that in the 10—20 cm layer. Nitrogen deposition did not change the original vertical distribution pattern of bacteria, fungi,