不同土地利用方式对三峡库区消落带土壤细菌和真菌多样性的影响

Effects of different land use patterns on soil bacterial and fungal biodiversity in the hydro-fluctuation zone of the Three Gorges Reservoir region

旨在为三峡消落带选择适合的生态恢复方式提供参考依据。以三峡库区重庆忠县汝溪河流域典型消落带为研究区域,于2015年6月进行原位取样,利用末端限制性片段长度多态性(Terminal Restriction Fragment Length Polymorphism,T-RFLP)方法,对消落带的耕地、林地、弃耕地土壤细菌和真菌群落多样性进行研究。研究发现:(1)除容重和密度外,不同用地类型对土壤各理化特性均产生显著影响,林地的含水量、有机质(OM)、全氮(TN)、全磷(TP)、速效氮(AN)、速效钾(AK)、速效磷(AP)的含量显著高于耕地和弃耕地(P<0.05)。(2)在三峡库区消落带不同土地利用方式下细菌和真菌多样性均有显著性差异。(3)耕地和林地的细菌多样性无显著性差异,均显著高于弃耕地;不同用地方式中,土壤全磷(TP)和速效磷(AP)显著影响细菌群落结构(P<0.05)。(4)真菌群落的Shannon-Weiner指数和辛普森指数在耕地中均为最低,但均匀度指数在3种用地类型之间没有显著性差异;在不同用地方式的土壤中,土壤有机质(OM)、全氮(TN)含量和p H显著影响真菌群落结构(P<0.05)。结论:与弃耕地和耕地相比,林地可固持、滞留和保有更多的土壤养分,有较高的细菌多样性和真菌多样性。在三峡消落带165—175 m海拔高程,林地为最适宜的用地方式,建议限制耕作,推广人工生态修复林地建设。

The goal of this study was to provide references for the environmental management of the Three Gorges Reservoir. To study the effect of different land use patterns on soil microorganism biodiversity in the hydro-fluctuation zone of the Three Gorges Reservoir. Surface soil samples were collected from the woodland, abandoned farmland, and farmland in June 2015 to determine the bacterial and fungal community biodiversity using the terminal-restriction fragment length polymorphism （T-RFLP） and soil chemical properties in the hydro-fluctuation zone of the Ruxi River basin, in Zhongxian County, Chongqing. Soil chemical properties were also investigated. Results showed that （1） the land use patterns significantly affected soil physicochemical properties, excluding bulk weight and density. Other soil physicochemical properties, such as soil moisture, content of soil organic matter, total nitrogen, total phosphorus, available nitrogen, available potassium, and available phosphorus, in the woodland were significantly higher than those of the other two types of land use （P 〈 0.05）; （2） there were significant differences among land use patterns in bacterial and fungal biodiversity; （3） the bacterial diversity index of the woodland was not significantly different from farmland, whereas both of them were significantly higher than abandoned farmland. Redundancy analysis and the Monte-Carlo test revealed that total phosphorus and available phosphorus showed a critical influence on bacterial diversity （P 〈 0.05）; and （4） the Shannon-Wiener index and the Simpson index of fungal community for the woodland and abandoned farmland were significantly higher than those of farmland, whereas there was not significant difference in richness index among the three types. Redundancy analysis and the Monte-Carlo test revealed that pH, organic matter, and total nitrogen played a critical roles in influencing fungal community diversity （P 〈 0.05）. Conclusion： compared to farmland and abandoned farmland, woodland can retain more soil nutrients, and improve soil bacterial, and fungal biodiversity, suggesting that the artificially regenerated woodland is the most appropriate land use type in the altitude of 165 m to 175 m in the hydro-fluctuation zone of the Three Gorges Reservoir. Those studies also propose that farming should be limited and the construction of artificially regenerated woodland in the hydro-fluctuation zone of the Three Gorges Reservoir region should be promoted.