Effects Of Different Land Use Types On Soil Microbial Biodiversity In The Hydro-fluctuation Zone Of The Three Gorges Reservoir Region

This study aimed to understand soil microbial biodiversity under different land use type 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 of the Ruxi river basin in Zhong County,Chongqing,was chosen as the study area.Soil samples were collected in June,2015 and 2016,respectively,to measure bacterial,fungal and actinobacterial biodiversity using the terminal-restriction fragment length polymorphism(T-RFLP)molecular method.Soil physicochemical properties were also investigated.Results showed that:(1)The land use type,soil depth and sampling time had significantly influence on soil physico-chemical properties in the hydro-fluctuation zone of the Three Gorges Reservoir region.Woodland soil fertility is superior to the abandoned farmland in the in the rural hydro-fluctuation zone.And the contents of soil nitrogen and potassium in the forest and abandoned farmland in rural hydro-fluctuation zone were higher than the corresponding woodland and grassland in the urban hydro-fluctuation zone.The result was attributed to the human disturbance and land use type.(2)There were significant differences among land use type,soil depth and sampling time in bacterial biodiversity.In the rural hydro-fluctuation zone,bacterial biodiversity index of woodland has no significant difference with farmland,while both of them were significantly higher than abandoned farmland;redundancy analysis and Monte-Carlo test revealed that available phosphorus,available potassium and total nitrogen were the critical factors influencing bacterial biodiversity(P < 0.05).And in urban hydro-fluctuation zone,bacterial biodiversity of grassland were significantly higher than woodland;water content and soil nutrients were the critical factors influencing biobacterial diversity(P < 0.05).(3)Fungal biodiversity were significant differences among land use types,soil depth and sampling time in the hydro-fluctuation zone of the Three Gorges Reservoir region;and fungal biodiversity decline with increased soil depth.In the rural hydro-fluctuation zone,fungal biodiversity of woodland and abandoned farmland were significantly higher than farmland;redundancy analysis and Monte-Carlo test revealed that nitrogen and phosphorous contents were the critical factors influencing fungal diversity(P < 0.05).And in urban hydro-fluctuation zone,fungal biodiversity of grassland wasn’t significant difference with woodland;bulk dengsity,total porosity,potassium and phosphorus contents were the critical factors influencing fungal diversity(P < 0.05).We recommend that farming should be limited and the construction of artificially regenerated woodland should be promoted in the hydro-fluctuation zone of the Three Gorges Reservoir region.(4)Actinobacterial biodiversity were significant differences among land use types and sampling time in the hydro-fluctuation zone of the Three Gorges Reservoir region.In the rural hydro-fluctuation zone,actinobacterial biodiversity of abandoned farmland ≥ woodland ≥ farmland;redundancy analysis and Monte-Carlo test revealed that pH value,organic matter,total potassium and available phosphorus contents were the critical factors influencing actinobacterial biodiversity(P < 0.05).And in urban hydro-fluctuation zone,actinobacterial biodiversity of woodland was not less than grassland;and bulk dengsity,total porosity,pH value,organic matter and available nutrient contents were the critical factors influencing actinobacterial biodiversity(P < 0.05).We propose that farming and human disturbance should be limited in the hydro-fluctuation zone of the Three Gorges Reservoir region.