3.2 Soil bacterial community structure
Soil bacterial community structure and diversity was determined based on 16S rRNA gene using pyrosequencing technique. In total, 7, 922 OTUs were obtained from 60 soil samples with the average number of 30,677 sequence per sample. Based on the relative abundance of OTU, we found that bacterial OTU richness (Figure 4a) and Shannon diversity (Figure 4b) in the maize field showed no significant difference with those of woodland irrespective of season (P > 0.05 for both). However, the NMDS ordination based on the relative abundance of OTU using Bray-Curtis distance showed that bacterial community structure in maize field was clearly separated from those in woodland. Furthermore, bacterial community structure from both land uses showed a clear pattern along the depth and seasonal variance (Figure 4c), which was further confirmed by PerMANOVA and ANOSIM analysis based on different land uses (P <0.01) and seasonal change (P < 0.05) (Table S1).