Abstract: As a major driver in nutrient cycling and energy flowing of terrestrial ecosystem, soil microorganisms are sensitive to the change of soil chemical property. In this study, by a temporalspatial substitution method, a secondary successional chronosequence of five different stages (young broadleaved forest, midaged broadleaved forest, mature broadleaved forest, mature broadleaved Korean pine mixed forest, and old broadleaved Korean pine mixed forest) in Changbai Mountains was chosen to compare the soil chemical properties and microbial community structure by phospholipid fatty acid (PLFA). The result indicted that soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) contents increased over succession while the C/N ratio decreased gradually. Soil microbial biomass, microbial community structure and composition changed with the forest succession. The total PLFAs, bacterial PLFAs, Grampositive bacterial PLFAs, Gramnegative bacterial PLFAs and Grampositive BactPLFA/Gramnegative BactPLFA (G+/G-) increased significantly, while the fungal PLFAs increased firstly and decreased lately. At the middle stage of the succession (mature broadleaved forest), the quantity of PLFA 18:2ω6c (an indicator of fungal biomass) was highest while the ratio of FungPLFA/BactPLFA was lowest. Correlation analysis showed that the microbial biomass was positively correlated with total carbon (TC), SOC, TN, TP contents and negatively correlated with C/N ratio. Redundancy analysis (RDA) indicated that TC, TN, SOC and C/N ratio were the main factors influencing microbial community structure.

Key words: nutrient solution supply, tomato, gas chromatography-mass spectrometry, volatiles, SPME