Abstract: [Objective] The community structure and diversity characteristics of soil nosZ-type denitrification microorganisms in the three kinds of primitive Pinus koraiensis forest (Picea koraiensis-Abies nephrolepis-Pinus koraiensis forest, Tilia spp. and Pinus koraiensis forest and Betula costata-Pinus koraiensis forest), Pinus koraiensis plantation and natural Pinus koraiensis secondary forest in Liangshui national nature reserve were analyzed to provide data support for a comprehensive understanding of the denitrification potential of different types of Pinus koraiensis forests and the nitrogen cycle process in the soil.[Method] The understory soils of five types of Pinus koraiensis forests were selected as the research object. The nosZ gene encoding nitrous oxide reductase (a key enzyme in the process of denitrification) of denitrification microorganisms was used as marker gene. The community composition and diversity characteristics of nosZ-type denitrification microorganisms in the soil were analyzed by high-throughput sequencing and bioinformatics analysis tequniques.[Result]The results showed that a total of 631 878 effective sequences of nosZ gene were obtained by high throughput sequencing from 15 soil samples in the five types of Pinus koraiensis forests, among which 579 871 sequences were high quality. These sequences were distributed between 178-383 bp but were mainly distributed around 260 bp. The main phyla of soil nosZ type denitrification microorganisms in five types of Pinus koraiensis forests were proteobacteria and bacteroidetes at the phylum level. However, the core genus included Burkholderia, Flavobacterium, Bradyrhizobium, Pseudomonas, Dechloromonas, Gemmatimonas, Achromobacter and Sinorhizobium. The analysis of alpha diversity of nosZ denitrifying microorganisms showed that the four alpha diversity index (Shannon, Chao1, ACE and Simpson index) of soil nosZ-type denitrification microorganisms among the five forest types were not siginificantly different, except that the Shannon and Simpson index of Betula costata-Pinus koraiensis forest was significantly higher than that of Pinus koraiensis natural secondary forest. Beta diversity analysis showed that there were significant differences in the composition of nosZ microbial communities in soils of five forest types (R=0.537,P=0.001), but there was no significantly different in the composition of three primitive Pinus koraiensis forests. Soil ammonia nitrogen and total nitrogen content were the main factors that significantly affected the nosZ type of denitrification microbial community (P<0.05).[Conclusion]There was no significant difference in the most alpha diversity index of soil nosZ-type denitrification microorganism, but beta diversity analysis showed that there were significant differences in the composition of nosZ microbial communities in soils of five forest types. The main environmental factors which influenced the composition and abundance of nosZ denitrification microorganisms over different forest types were soil ammonium nitrogen and total nitrogen.

Key words: primitive forest of Pinus koraiensis, plantation, natural secondary forest, nosZ gene, high-throughput sequencing, nitrifying microorganism