3.3 | Distribution of bacteria in soil samples
At the phylum level, Proteobacteria, Chloroflexi, Acidobacteria, and Actinobacteria were the dominant bacteria in all the samples, accounting for 88.23% of the total sequence data. Other abundant phyla were GAL15, WPS-2, Verrucomicrobia, Bacteroidetes, Gemmatimonadetes, and Planctomycetes (Figure 3a). The phyla with comparatively high relative abundance, namely, Chloroflexi, Acidobacteria, Actinobacteria, and WPS-2, were all significantly lower at the 40–60 cm soil depth than for the other depths, except for Proteobacteria (Figure 3b). At different slope positions, the relative abundance of Proteobacteria was the lowest at the top of the slope, while that of Acidobacteria was the highest. The relative abundance of Actinobacteria was lowest at the midslope (Figure 3c). In the different forest types, the abundance of Proteobacteria was the highest in LF. The abundance of Chloroflexi and Acidobacteria were highest in NA and lowest in LF, while the abundance of Actinobacteria was highest at LF and lowest in GNA. There were no significant differences in the abundance of Chloroflexi between the forest types (Figure 3d).
Plantation altered the relative abundance of the dominant phyla (Figure 4) in different forest types, with Acidobacteria, WPS-2, and Rokubacteria showing highly significant differences(p< 0.01.Significant differences in the abundance of Actinobacteria, unclassified_k_norank_d_Bacteria, and Gemmatimonadetes were recorded, while the relative abundance of Proteobacteria did not differ significantly. There were no significant differences in the bacterial communities at different depths or slopes.