Changes in Metabolic Functions of the Soil Microbial Community in Eucalyptus Plantations Along an Urban-rural Gradient

Urbanization has been shown to influence the composition and diversity of soil microbial communities. However, the functional response of the soil microbial community to urbanization is not well studied. In this study, we used the Biolog Microplates method to characterize microbial catabolic profiles in Eucalyptus plantations of soil samples from urban, suburban and rural sites in Guangzhou, China. The results showed that there were significant differences in the average well-color development (AWCD) of all carbon sources among the three urban-rural plantations microbial communities, and the Simpson functional diversity index showed significant differences. Soil microbial metabolic activity showed a significantly negative correlation with soil variables (pH, total nitrogen, available Cu, available Zn, total Pb, total Cr and total Cd) except bulk density and organic carbon. Additionally, the three urban-rural plantations microbial communities differed significantly in the metabolic utilization of carbohydrates, phenols, amino acids and amines, however there were no significant differences in the carboxylic acids and polymers. Furthermore, the principal component analysis revealed that the microbial communities of three urban-rural plantations had obviously different metabolic functions. These results revealed that urbanization distinctly decreased soil microbial activities and affected soil microbial function.