ORIGINAL ARTICLE

Abstract To evaluate the microbial diversity of Fushan forest soils, the variation of soil properties, microbial populations, and soil DNA with soil depth in three sites of different altitude were analyzed. Microbial popula-tion, moisture content, total organic carbon (Corg), and total nitrogen (Ntot) decreased with increasing soil depth. The valley site had the lowest microbial popula-tions among the three tested sites due to the low organic matter content. Bacterial population was the highest among the microbial populations. The ratios of cellu-lolytic microbes to the total bacteria in organic layers were high, implying their roles in the carbon cycle. The microbial biomass carbon (Cmic) and nitrogen (Nmic) contents ranged from 130.5 to 564.1 lg g1 and from 16.7 to 95.4 lg g1, respectively. The valley had the lowest Cmic and Nmic. The organic layer had the highest Cmic and Nmic and decreased with soil depth. Analysis using denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) amplicons of 16S rDNA showed that the bacterial diversity of the three sites were very similar to each other in the major bands, and the variation was in the minor bands. However, the patterns in PCR-DGGE profile through gradient hori-zons were different, indicating the prevalence of specific microbes at different horizons. These results suggest that the microbial diversity in the deeper horizons is not simply the diluted analogs of the surface soils and that some microbes dominate only in the deeper horizons. Topography influenced the quantity and diversity of microbial populations