Effects Of Disturbance On Aboveground Vegetation Diversity And Soil In Tundra Zone Of Changbai Mountain

In this study,we took the disturbed plant communities from the north slope and west slope of Changbai Mountain as the research object and analyzed the aboveground plant community composition and structure of the interference group and control group.We also measured the soil physicochemical properties and enzyme activities of different interference groups and analyzed the microbial community structure in soil environment of different interference groups with the PCR-RFLP technique.Through the above experiments,we studied the effects of disturbance on the aboveground plant diversity,soil physical and chemical properties and microbial community on Changbai Mountain tundra and the correlation among them.The main conclusions are as follows:1.Changes in aboveground plant diversityWith the presence of interference,the coverage and height of plants decreased significantly,the number of plants species increased slightly,and the vegetation type became meadow.This trend was more obvious under the interference of scientific research.The Shannon diversity index,Simpson dominance index and Pielou evenness index all increased significantly,while the Gleason richness index increased slightly,which was more obvious under the interference of scientific research.The niche width of the original dominant species showed a decreasing trend,and some dominant species even disappeared completely in the interference group.2.Changes in soil physical and chemical properties and microbial communitiesSoil p H,soil ammonium nitrogen and soil nitrate nitrogen increased slightly,while soil water content,soil organic carbon and soil C/N ratio decreased slightly in the interference group.Soil sucrase activity increased slightly in the interference group,while catalase,urease and phosphatase activities decreased slightly in the interference group.Soil fungal biomass increased slightly,but not significantly.With the disturbance,the soil microbial community structure changed: the diversity of bacterial community and actinomycetes community increased and the structure was more stable,while the diversity of fungal community showed a declining trend.3.The relationship between aboveground plants and soilThe relationship between soil catalase,soil sucrase and soil moisture content and soil physicochemical properties and enzyme activities changed after the disturbance.The correlation between soil catalase,soil sucrase and soil moisture content and aboveground plants was the most obvious,and the trend and degree of change were also different under the two types of disturbance.The relationship between soil microbial diversity index and aboveground plant diversity index also changed,among which the relationship between bacterial evenness index and plant diversity index changed most obviously,and the trend and degree of change were also different under the two different forms of disturbance.This study mainly explored the impact of human disturbance(tourism and scientific research)on the tundra ecosystem of Changbai Mountain,and scientifically predicted the impact and development trend of the disturbance,providing theoretical basis for the restoration,reconstruction and scientific management of the damaged ecosystem.