The soils of the spruce-red pine forest,the maple-brown pine forest,the eucalyptus red pine forest and the Mongolian pine-song pine forest in the Liangshui National Nature Reserve were studied.The dilution plate method and microplate method were used to study soil microbial characteristics between different soil layers of the four forest types.The results showed that the total microbial population of four forest types varied from 1.60 to 620 million cfu/g,and the difference of bacterial content was the largest.The difference of soil microbial activity among different forest types reached a significant level(P<0.05).The average color change rate of ECO microplates cultured under constant temperature for 24 h showed a consistent law of increasing gradually with time,until the rising speed of 168 h tended to be gentle.The diversity indices of soil microbes in four forest types showed a trend of decreasing with the increase of soil depth,and the differences among different forest types in the same soil layer were significant(P<0.05).The carbon source produced a strong metabolic capacity,which further verified the ammonium-promoting properties of Pinus koraiensis.From the principal component analysis(PCA),the metabolic capacity of various forest types and the underlying soil microorganisms on various carbon sources appeared spatially.The more significant differences are consistent with the AWCD values and the various diversity indices.