Effects of Elevated CO2 on Soil Microbial Activity and Bacterial Diversity in Pinus koraiensis Seedlings Fields in Changbai Mountain

This study focused on soil microbial activity and bacterial diversity exposed to long-term elevated CO₂. Bacterial numbers, microbial biomass C, soil basal respiration, dehydrogenatase activity, and bacterial diversity were investigated in pinus koraiensis seedlings. The results indicated bacterial numbers decreased significantly (p ≤ 0.05) at elevated CO₂ in July and August, but not of it in September. Microbial biomass C decreased significantly (p ≤ 0.001) at 700 μ mol/mol CO₂ compared to screened ambient and ambient, but not of it under 500 μ mol/mol CO₂. Soil basal respiration (p ≤ 0.05) and dehydrogenatase activity (p ≤ 0.001) increased significantly under elevated CO₂ compared to ambient and screened ambient. Bacterial community structure changed evidently under elevated CO₂ compared to ambient through DGGE (Denaturing Gradient Gel Electrophoresis) analysis of bacterial 16S rDNA gene fragments amplified by PCR from DNA extracted directly from soil. It was concluded that soil microbial activities and bacterial diversity were significantly influenced by elevated CO₂ compared to ambient.