| With the continuous development of tourism industry and the rapid growth of social economy,the contradiction between rational development and natural environment protection is becoming increasingly prominent.Changbai Mountain is welcomed by the public because of its unique landscape,but it has an inevitable impact on the tundra ecosystem of Changbai Mountain.Changbai Mountain tundra zone is one of the only three tundra in China,which has important ecological and economic value,but there is little research on the impact of tourism interference on the tundra zone at present.This study selects the plants and soil of Changbai Mountain tundra zone as the research object,and selects two typical tourism interference areas of highway and steps to analyze the impact of tourism interference on the composition and structure of plant community through the investigation of aboveground vegetation;ISSR Molecular marker technique was used to analyze the effect of tourism interference on the genetic diversity of dominant constructive species-Rhododendron Kraft;The changes of soil microbial community structure of tundra plant community in the interference area were detected,and the effects of interference on soil physical and chemical properties,enzyme activity and the relationship between soil environmental factors and microorganisms were analyzed.The main results are as follows:1.The composition and structure of different plant communities are different under Tourism interference.It is mainly manifested in the decline of the important value of dominant species,the decline of niche width and the replacement of dominant species in the community;Plant communities on both sides of the road without human trampling and on the north side of the steps with less human trampling ?-The diversity index increased,but man-made trampling was serious in the area ?-The diversity index decreased significantly.The plant community structure has changed.Compared with herbaceous plants,the importance value of Shrubs under Tourism interference has decreased more obviously.There are almost no shrubs in areas with serious human trampling.Shrubs are more sensitive to tourism interference,and there may be a risk of meadow in the tundra of Changbai Mountain.2.Research on the genetic structure of Rhododendron aureum,a dominant construct in the tundra belt of Changbai Mountains under tourism disturbance showed that the percentage of PPL polymorphic sites of Rhododendron aureum was 64.41%and expected heterozygosity He was 0.212 and Shannon's information index(I)was0.321,indicating that Rhododendron aureum had a relatively high genetic diversity.For the genetic diversity index of cowhide Rhododendron aureum,only the interference group 3 in sample plot II(0-20 M away from the highway boundary)is slightly lower than the control group,and the interference groups in other sample plots are higher than the control group.Although lighter tourism disturbance has a certain promotion effect on genetic diversity.For example,disturbance group 1(40-60 meters away from the road boundary)has the highest genetic diversity,but as the distance from the road boundary increases,the intensity of disturbance increases,and the genetic diversity increases.Sexual decline.Nei's genetic structure analysis showed that the genetic differentiation coefficient of Rhododendron aureum under tourism disturbance was 0.043,and the genetic differentiation coefficient of Rhododendron aureum on both sides of highway was0.029,indicating that tourism disturbance did not lead to significant genetic differentiation of Rhododendron aureum on both sides of highway,and the genetic differentiation of populations on both sides of highway was very weak.According to the results of cluster analysis and principal coordinate analysis,it was found that disturbance group 1 and 2 clustered into one branch respectively,and interference group3 clustered into one branch with control group,indicating that there was some genetic differentiation between interference population and control population under tourism disturbance,but this genetic differentiation was not significant.The results of AMOVA molecular variation analysis showed that the genetic variation within the population of Rhododendron aureum was 84%,and the genetic differentiation of Rhododendron aureum mainly occurred within the population.3.Analysis on the changes of soil factors and microbes under tourism disturbance found that the content of soil organic carbon,total nitrogen,moisture,nitrate nitrogen,ammonium nitrogen decreased,the p H value increases,the sucrase,urease,phosphatase,catalase activity decreased,suggested that tourism disturbance reduced the soil carbon and nitrogen cycle and the soil fertility.PCR-RFLP analysis on microbial community diversity under tourism disturbance found that the similarity coefficient of soil bacteria,fungi,actinomycetes community structure between the control group and the disturbance group were relatively low.The similarity coefficient of microbial community structure between the either side of the highway and stairway were also relatively low,indicated that tourism disturbance altered the microbial community structure and reduced the stability of community structure.According to Spearman's correlation analysis results showed that urease activity and total nitrogen were the main soil factors affecting microbial community in the control group,and water content and nitrate nitrogen were the main soil factors affecting microbial community in the interference group along the highway.The main soil factors were phosphatase activity in the control group,p H and ammonium nitrogen in the interference group along the stairway.The results indicated that soil environmental factors may cause the difference in soil microbial community,and tourism disturbance altered the relationship between soil factors and microbial community.The correlation between soil environmental factors was also affected by tourism disturbance.Soil environmental factors were also closely related to plant community diversity.The results showed that richness index of the control group along the highway was significantly correlated with ammonium nitrogen and sucrase activity,while p H and total nitrogen were significantly positively correlated with the interference group.There was no significant correlation between richness index and soil factors in the control group along the stairway,while there was significant correlation between soil moisture and organic carbon in the disturbance group.The results showed that tourism disturbance altered the correlation between plant community and soil factors.In conclusion,tourism disturbance disrupted the composition,structure and interspecific relationships of plant communities in the tundra.Tourism disturbance affects the genetic diversity of Rhododendron aureum,the dominant plant in the tundra,and the increase of disturbance intensity will reduce the genetic diversity of Rhododendron aureum.Tourism disturbance reduces soil quality and fertility,reduces carbon and nitrogen cycle function,changes microbial community structure and reduces community stability and soil and plants respond comprehensively to tourism disturbance. |
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