Functional structures of soil microbial community relate to contrasting N2O emission patterns from a highly acidified forest.

Nitrous oxide (N 2 O) is an important greenhouse gas contributing to global climate change. Emissions of N 2 O from acidic forests are increasing rapidly; however, little is known about the mechanisms driving these emissions. We analyzed soil samples from a high N 2 O emission area (HEA, 224–601 μg N m−2 h−1) and an adjacent low emission area (LEA, 20–30 μg N m−2 h−1) of a highly acidified forest. HEA showed similar carbon and nitrogen (N) pools and microbial biomass to LEA, but significantly higher moisture and extractable nutrients than LEA did. GeoChip 4 detected 298 gene families (unadjusted P < 0.05; 94, adjusted P < 0.05) showing significantly different structures between HEA and LEA. Both areas had highly diverse N cycling functional genes. However, HEA had higher relative abundances of nor , P450nor, and archaeal nitrifier nirK , which provided evidence for the importance of denitrifiers in N 2 O emission. HEA also showed significantly higher relative abundances of lignin- and cellulose-degrading genes, oxygen-limitation-response genes and denitrifier ppk , but lower abundances of N- and phosphorus (P) -limitation-response genes especially denitrifier pstS , corresponding to the higher moisture and extractable nutrients conducive to denitrification. The moisture, extractable nutrients and pH explained over 50% variation in microbial communities, and extractable P appeared as the key factor driving community variation and consequently regulated N 2 O production. N 2 O emission in highly acidified forest soils was related to the diverse N functional genes, especially denitrification genes, and was affected by soil properties. Unlabelled Image • N 2 O emission rates were high in the TSP forest but also diverse in different sites. • Nitrogen cycling function genes were diverse in acidified forest soils. • Functional genes in denitrifiers were positively correlated to N 2 O emission. • Phosphorus showed significant influence on microbial gene communities. [ABSTRACT FROM AUTHOR]