不同干扰方式对喀斯特生态系统土壤细菌优势类群—变形菌群落的影响

以喀斯特原生林为对照,运用16S rRNA基因的PCR-RFLP和测序技术对该区不同人为干扰方式下土壤细菌的群落结构进行了分析。结果显示,4个样地中变形菌占总克隆子数的41.3%,是研究区土壤中的优势细菌类群。与原生林地相比较,受人为干扰的生态系统土壤中变形菌明显减少,自然恢复地、农耕地和放牧+冬季火烧草地减少了30.2%～47.4%。自然恢复地、放牧+冬季火烧草地与原生林地土壤中变形菌的4个亚群丰度分布关系一致,均为α->δ->β->γ-变形菌,而农耕地则为δ->α->β->γ-变形菌,说明自然恢复和放牧+冬季火烧草地对喀斯特土壤变形菌的恢复作用有限,而对变形菌4个亚群之间的分布关系有明显的正效应,尤其是自然恢复地中α-变形菌得到了很好的恢复,较农耕地增加了130%。四个样地中,占总克隆子数16.5%的克隆子被归类为根瘤菌目,且以原生林地最多,是3个干扰样地的1.6～3.7倍。基于以上研究结果,未来可考虑种植本土固氮植物结合接种相应的固氮微生物作为恢复喀斯特退化生态系统的措施之一。

EFFECT OF HUMAN DISTURBANCE ON COMPOSITION OF THE DOMINANT BACTERIAL GROUP PROTEOBACTERIA IN KARST SOIL ECOSYSTEMS

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.