Abstract:With a Karst primeval forest (KPF) set as check, effects of human disturbance on community structure of soil bacteria were analyzed using the 16S rRNA genes PCR-RFLP and sequencing techniques. Results show that Proteobacteria were the dominant bacterial group in all the four soils subjected to different patterns of human disturbance, primeval forest (KPF, free of disturbance), naturally restored land (KNR), cropland (KMS) and grassland disturbed by long-term grazing and burned annual in winter (KGB), separately, accounting for 41.3% of the total clone libraries. As compared to KPF, the proportions of Proteobacteria were decreased by 30.2%~47.4% in disturbed soils (KNR, KMS and KGB). Similar distributions of the subgroups of Proteobacteria were found among KPF, KNR and KGB, being in the order of α->δ->β->γ-Proteobacteria, but in KMS it was in the order of δ->α->β->γ-Proteobacteria, which indicate that the effects of natural restoration and grazing and burning in winter were limited on recovery of soil Proteobacteria, but obviously positive on distribution sequence of the four subphyla. In KNR, the subphylum of α-Proteobacteria was well restored, being 130% higher than in KMS. In the four soils, 16.5% of the total clones were sorted into Rhizobiales, which was the highest in KPF, about 1.6 to 3.7 times higher than in the other three soils. Based on the above-described findings, it is concluded that planting of native nitrogen-fixing plants in combination with inoculation of native nitrogen-fixing microorganisms may be considered as one of the measures in future to restore degraded Karst ecosystems.