Abstract: Understanding soil microbial carbon source utilization and functional diversity of typical native broadleaved artificial forests is of great importance in tree species selection for vegetation restoration and reconstruction of hilly red soil areas in south subtropical China. By using BiologEco technology, we studied the soil microbial carbon source utilization and functional diversity at different soil depths (0-20, 20-40 and 40-60 cm) of four typical native broadleaved planted forests (Castanopsis hystrix, Mytilaria laosensis, Michelia macclurei and Paramichelia bailonii) and exotic fastgrowing eucalyptus plantation in the Fubo Forest Farm in Pingxiang, Guangxi. The results showed that the optimum incubation time for the capacity of soil microbes using monocarbon source in the five planted forests was 108 h. The capacity of soil microbial carbon source utilization of the different planted forests increased with the incubation time, and decreased with the soil depth. At the incubation time of 108 h, the capacity of soil microbial carbon source utilization among the four native broadleaved planted forests had no significant difference, but it was higher than that of the eucalyptus plantation. The Shannon index and Simpson index indicated that the functional diversity of soil microbial community of the four native broadleaved planted forests were different at various soil depths, and they were higher than those of the eucalyptus plantation at the same soil horizon. The principal component analysis and cluster analysis of 31 carbon sources indicated that carbohydrate, amino acid, polymerizer, carboxylic acid and aromatic carbon were sensitive carbon sources to the functional diversity of soil microbial communities in the different planted forests.

Key words: Castanopsis carlesii secondary forest, clear-cutting, logging residue, decomposition rate, chemical composition.