Effects Of Tourism Disturbance On The Characteristics Of Soil Respiration And Its Impacted Factors Of Mountain Meadow Ecosystem In Kanas Scenic Area

Soil respiration is one of the important sources of atmospheric CO₂ and plays a vital role in the global carbon cycle.Grassland ecosystems are an important part of terrestrial ecosystem carbon pools,affecting the process and ecological consequences of the global carbon cycle.Therefore,in this study,the mountain meadow in Kanas Scenic Area was taken as the research object.Based on the daily dynamic changes of soil respiration and its water heat relationship of fixed-point observation interference(guanyutai interference,GYd;Yaze Lake interference,XSd)and undisturbed sample plots(guanyutai interference,GYn;Yaze Lake interference,YZn)from June to July in 2018 and 2019,the quantitative characteristics,species composition,plant diversity and productivity of mountain meadow before and after tourism disturbance were monitored,as well as changes in Soil Eco stoichiometry,soil enzyme activities and composition of soil bacterial communities.The internal relations between soil respiration rate and the quantitative characteristics of community,plant diversity,productivity,ecological stoichiometry of plant and soil,soil biological activity and soil bacterial composition were analyzed,main research results are as follows:(1)The average height,total coverage and Shannon Wiener index of plant community decreased significantly after tourism disturbance,and community density,aboveground biomass and other plant species diversity index also decreased.After the disturbance of tourism,the dominant species of the original community,such as pea,elm,erect Potentilla,Polygonum punctatum and myrtle Granna,gradually disappeared or decreased in the community,while the trampling resistant and unnoticed bromwear,bryophylla and Trifolium were increasing,and the important value of the dominant species was more concentrated.The C,N and P contents of plant community decreased after tourism disturbance,and C/P and N/P increased significantly,while the change rule of C/N was affected by the survey time and altitude of the sample site.(2)The content of C,N,P and C/N,C/P,N/P in the 0-10 cm soil decreased with tourism disturbance.The activities of urease,invertase and protease in 0-10 cm soil of Kanas mountain meadow decreased and the activities of catalase increased due to tourism disturbance.The soil bacteria in the 0-10 cm soil layer of the meadow in Kanas mountainous area were mainly composed of Actinobacteria,Proteobacteria,acidobacteria,Chloroflexi,Firmicutes and verrucomicrobia.At the genus classification level,they were mainly composed of norank?c?subgourp?6?norank?c?Acidobacteria?RB41?norank?o?Gaiellales?norank?c?KD4-96?norank?f?67-14,bacillus,solirubrobacter and Nitrospira.Firmicutes,verruca and Curvularia were highly tolerant to the disturbance,and their relative abundance increased after the tourism disturbance,while Proteus and actinomycetes were affected by the decrease of soil C content and soil water content,and their relative abundance decreased after the tourism disturbance.Bacillus,RB41 and nitrifying spirochetes are known to have their functions,which can be used to explain the relationship between the structure and function of soil bacterial community in Kanas mountain meadow before and after tourism disturbance.After tourism disturbance,the species richness and diversity index of soil bacteria in 0-10 cm soil layer showed a downward trend,and the living environment of soil bacteria was disturbed.(3)The daily dynamic change of soil respiration rate of mountain meadow in Kanas Scenic Area showed a single peak curve,and the maximum value appeared around 14:00-18:00.After tourism disturbance,soil temperature of mountain meadow increased significantly,soil water content decreased significantly,and soil respiration rate and temperature sensitive index decreased significantly.Soil respiration rate was positively correlated with soil temperature and negatively correlated with soil water content.(4)The results showed that the average height,total coverage,community density and aboveground biomass of mountain meadow community were negatively correlated with soil respiration rate,and the change of species composition and quantitative characteristics of community could indirectly lead to the change of soil respiration rate;the C,N,P contents and their stoichiometric ratios of aboveground part of the community had no significant correlation with soil respiration rate,but had little effect on soil respiration rate.Soil respiration rate was positively correlated with soil C content,and negatively correlated with soil N and P content;soil respiration rate was positively correlated with soil C/N and C/P,and negatively correlated with soil N/P.Therefore,the disturbance of soil nutrient circulation and the decrease of soil respiration rate are often synchronous.(5)Soil respiration rate was negatively correlated with the activities of soil protease,urease and sucrase,and positively correlated with the activity of soil catalase.Soil respiration rate was positively correlated with relative abundance of actinobacteria and Proteus,and negatively correlated with relative abundance of acidobacteria.The changes of soil enzyme activity,bacterial diversity and group composition can lead to the changes of soil respiration.Therefore,sustainable carbon management measures in mountainous meadow in Kanas area need to control the intensity of tourism disturbance activities and reduce the impact of tourism disturbance on plant communities,soil environment,soil nutrient cycling and soil biological activities.