林分类型对亚热带森林土壤团聚体中真菌反硝化微生物丰度的影响OACSTPCD

Soil samples were collected from Castanopsis carlesii secondary forest,Cunning-hamia lanceolata plantation and Pinus massoniana plantation in Sanming City,Fujian Province to determine the abundance of FnirK gene using real-time quantitative PCR and denitrification potential measurements.Results showed that forest types significantly affected the abundance of the FnirK gene,but less by aggregate sizes.The highest gene copy number of FnirK was 5.30×108 copies·g-1 in the P.massoniana plantation,which was significantly higher than 2.49×108 copies·g-1 in the C.lanceolata plantation and 1.21×108 copies·g-1 in the secondary forest.The same trend was observed in different aggregate sizes.Larger aggregates in C.lanceolata and P.massoniana planta-tions exhibited higher FnirK gene copy numbers and lower in smaller aggregates,while no signifi-cant difference was found in the four aggregate sizes in secondary forests.The denitrification poten-tial in soils from P.massoniana plantation and C.lanceolata plantations was 10.23 and 6.41 μg·kg-1·h-1,respectively,which was significantly higher than the 2.76 μg·kg-1·h-1 in soils from the secondary forest.Correlation analysis showed that FnirK gene abundance was positively correlated with soil moisture and available phosphorus content,and denitrification potential was positively cor-related with soil pH,moisture content,available phosphorus content and FnirK gene abundance.These findings indicate an important role of fungi in denitrification in acidic forest soils.Overall,different forest types influenced the abundance of FnirK gene and denitrification potential mainly through regulating soil moisture and available phosphorus content,while the aggregate size had a relatively minor impact on FnirK gene abundance.Consequently,the contribution of soil fungal denitrification to N2 O production in plantations should not be overlooked in forest management.