三峡库区城乡消落带人工植被恢复土壤放线菌多样性特征

为研究人工植被恢复后消落带土壤放线菌群落多样性特征,以三峡库区典型城市消落带重庆江北嘴大剧院消落带和乡村消落带忠县汝溪河流域消落带为研究区域,于2015年6月原位采集0~20 cm、20~40 cm、40~60 cm土壤,利用限制性末端长度多态性(terminal restriction fragment length polymorphism,T-RFLP)方法,对消落带人工恢复植被土壤不同土层的放线菌群落多样性进行研究.结果发现:(1)三峡库区城乡消落带人工植被恢复后的土壤放线菌多样性有差异,表现为城市消落带土壤放线菌多样性高于乡村消落带土壤(P0.05),特别是在表层土壤.(2)在城乡消落带中,林地土壤放线菌多样性高于草地,且在土层之间放线菌多样性无显著性差异.(3)三峡库区城乡消落带人工植被恢复后的土壤放线菌优势种有差异.(4)冗余分析(redundancy analysis,RDA)和蒙特卡罗置换检验(Monte-Carlo permutation test)表明,城市消落带中含水量、速效氮含量显著影响放线菌群落多样性;乡村消落带中土壤含水量、有机质、速效氮和速效钾含量显著影响放线菌群落多样性.结论表明在消落带人工植被修复后,城市消落带土壤放线菌多样性均高于乡村消落带,这有可能是人为干扰和土壤养分增加所致.

Comparative Studies on Soil Actinobacterial Biodiversity After Re-vegetation in the Urban and Rural Hydro-fluctuation Zone of the Three Gorges Reservoir Region

This study aimed to understand the soil actinobacterial community diversity in the urban and rural hydro-fluctuation zone of the Three Gorges Reservoir region. The hydro-fluctuation zone of Chongqing Great Theatre in Jiangbei District and the Ruxi river basin in Zhong County, Chongqing, was chosen as the study area. Soil samples were collected in June 2015, to measure actinobacterial biodiversity using the terminal-restriction fragment length polymorphism (T-RFLP) molecular method. Results showed that:1 The actinobacterial biodiversity was different in the urban and rural hydro-fluctuation zone after artificial vegetation restoration. The actinobacterial biodiversity of the urban hydro-fluctuation zone was significantly higher than that of the rural hydro-fluctuation zone (P<0.05), which was most obvious in the surface soil. 2 The actinobacterial biodiversity of woodland was higher than that of grassland, but there was no significant difference in the actinobacterial biodiversity among the three soil layers in both the urban and rural hydro-fluctuation zone. 3 The dominant species of actinomycetes was different in different samples. 4 Redundancy analysis and the Monte-Carlo test revealed that water content and available nitrogen (AN) played a critical role in influencing actinobacterial biodiversity in the urban hydro-fluctuation zone (P<0.05). In contrast, the water content, organic matter (OM), available nitrogen (AN) and available phosphorus (AP) played a critical role in influencing actinobacterial biodiversity in the rural hydro-fluctuation zone of the Three Gorges Reservoir region (P<0.05). Thus, we concluded that the actinobacterial biodiversity of the urban hydro-fluctuation zone was significantly higher than that of the rural hydro-fluctuation zone in the Three Gorges Reservoir region, and such a result was attributed to the increased human disturbance and soil nutrients.