The Spatial Heterogeneity Of Soil Microorganism And Organic Matter In Broad-leaved Korean Pine Forest In Changbai Mountain

Soil microorganism is the main driver of soil biochemical cycle,and actively participates in the material circulation and energy flow in ecosystem,playing a key role in regulation and maintenance of soil biogeochemical process and of ecosystem functions.The research on small-scale spatial heterogeneity of soil microbial and its influence mechanism in forest ecosystem is going to provide theoretical basis for better evaluation of soil microbial ecological effect in regulation of biogeochemical process as well maintenance of the ecosystem functions,and it is also of very importance to promote sustainable development and strengthen the management and regulation of ecosystems.In this study,the soil in 0-10 cm and 10-20 cm depths in a 40×50 m sample area in a broad-leaved mixed forest in Changbai Mountain was sampled.The Phospholipid fatty acid(PLFA)and Biolog technology was used to analyze the soil microbial community structure and functional diversity respectively.And then the geostatistics was used to analyze the spatial distribution of organic matter fractions,soil microbial community structure and function diversity.Furthermore,the multivariate statistical analysis was used to explore the SOM-Soil microorganism mechanism.The results showed that:(1)Soil organic carbon(SOC)and total nitrogen(TN)were significantly correlated.And the labile organic matter fractions were positively correlated with the total organic matter except the dissolved organic nitrogen(DON)in 0-10 cm layer and the particulate organic carbon(POC)and particulate organic nitrogen(PON)in 10-20 cm layer.(2)The spatial heterogeneity of soil organic fractions shows differences in 0-10 cm layer:TN,microbial biomass carbon(MBC),microbial biomass nitrogen(MBN)and DON presented strong spatial autocorrelation,SOC and dissolved organic carbon(DOC)moderate spatial autocorrelation,POC and PON did not exist spatial autocorrelation.With the increase of soil depth,all soil organic matter fractions showed strong spatial autocorrelation.(3)Bacteria was the main composition of soil microorganisms in Broad-leaved Korean Pine Forest in Changbai Mountain and it accounted for 74.38%and 73.17%of the total PLFA in 0-10 cm and 10-20 cm respectively.The amounts of different PLFA in the surface soil were generally higher than the lower,but fungi/bacteria and G +/G-in surface were just the opposite.(4)Soil microbial community had different spatial heterogeneity.Total PLFA,bacteria,actinomycetes and gram positive bacteria showed a high degree of spatial autocorrelation.Gram negative bacteria in the surface showed moderate spatial autocorrelation,and the spatial variation could explain 74.1%of the total variation.(5)Soil microorganisms had a higher utilization of carboxylic acids,amino acids and Carbohydrates,while the utilization of amines,polymers and Miscellaneous were lower.The metabolic activity in 0-10 cm layer was generally higher than 10-20 cm layer.(6)Soil microbial metabolic activity showed a moderate spatial autocorrelation,the spatial variation explained 58.5%and 62.6%of the total variation in 0-10 cm and 10-20 cm respectively;Soil microbial metabolic diversity showed strong spatial autocorrelation,the spatial variation explained 85.4%and 100%of the total variation respectively.(7)Soil organic matter fractions had a significant effect on functional diversity:in 0-10 cm layer,DOC,POC and MBC can explain 16%,10%and 6%of the variation,and in 10-20 cm layer,DOC,MBC and POC explained 22%of the variation totally.Soil microorganisms was little influenced by the soil organic matter fractions:in 0-10 cm layer,soil microbial community structure was not affected.In 10-20 cm layer,MBC significantly affected soil microbial community structure,which could explain 17%of the variation.