Effects Of Litter On Native Plants And Soil Microorganisms In Tundra On The Western Slope Of Changbai Mountain

In the context of global warming,the Poaceae plants have invaded the tundra belt on the west slope of Changbai Mountain in the past three decades,resulting in a large amount of Deyeuxia angustifolia litter fall.By setting up litter removal,recovery,and addition plots in the tundra belt and conducting continuous monitoring for four years,this study explores the impact of litter fall on the local vegetation and soil microorganisms in the tundra belt.The research findings are as follows:(1)Litter can significantly affect plant morphology and community structure.Litter significantly affects plant morphology and plant community α-diversity by influencing the community’s net photosynthetic rate in the plots.In woody plots,removing litter can temporarily suppress the growth of Deyeuxia angustifolia,but its growth trend increases year by year,while promoting the growth of local plants like Rhododendron aureum Franch..Restoring or adding litter can significantly inhibit the growth of woody plants like Rhododendron aureum Franch.In herbaceous plots influenced by the invasion of Deyeuxia angustifolia,removing litter has a suppressive effect on their growth,promoting the growth of other companion plants.Restoring or adding litter results in a significant upward trend in Deyeuxia angustifolia growth,inhibiting the growth of companion plants.The results suggest that litter can affect the growth of Deyeuxia angustifolia,Rhododendron aureum Franch,and companion plants,as well as the invasion process of Deyeuxia angustifolia.(2)Litter can significantly alter soil physical and chemical properties,soil enzyme activity,and soil microorganisms.In woody plots,removing litter significantly changes soil urease activity and ammonium nitrogen content.Ammonium nitrogen can activate soil acid phosphatase activity,so removing litter can change soil properties in a direction more favorable for the growth of Deyeuxia angustifolia.In woody addition plots not affected by the invasion of Deyeuxia angustifolia,adding litter significantly changes soil urease activity and nitrate nitrogen content,promoting the growth of Deyeuxia angustifolia and inhibiting the growth of local woody plants.The different treatments of litter in herbaceous plots do not significantly affect soil properties.In both woody and herbaceous plots,litter removal alters the α-diversity and β-diversity of soil fungi and bacterial communities,but the changes are not significant.Restoring litter significantly changes the β-diversity of herbaceous bacterial communities,while adding litter similarly significantly changes the β-diversity of fungal and bacterial communities in woody plots.Changes in litter can significantly alter the functions of soil bacteria and fungi in herbaceous and woody plots.Bacterial function mainly changes the types of required carbon sources,while fungal function mainly changes the sources of glucose.The degree of change in soil bacterial communities is greater than that in fungal communities,and the degree of change in woody plot soil bacterial communities is greater than that in herbaceous plot bacteria.(3)Conduct a comprehensive analysis of the impact of different litter treatment methods on vegetation and soil.Results of multiple factor analysis(MFA)show that different litter treatment methods have a strong impact on plant morphology,plant community α-diversity,and soil bacterial α-diversity in woody plant communities;while in herbaceous plant communities,soil fungal α-diversity,soil physical and chemical properties,enzyme activity,and community net photosynthesis rate are strongly affected.(4)Model prediction of soil physical and chemical properties,soil enzyme activity,and dominant species growth status.The Logistics model prediction results show: Continuously removing litter in woody plots will lead to an increasing trend in soil enzyme activity and a decreasing trend in physicochemical properties,while restoring litter will cause a decreasing trend in soil enzyme activity and an increasing trend in physicochemical properties.Adding litter will result in an increasing trend in both soil enzyme activity and physicochemical properties.In herbaceous plots,continuously removing litter leads to declining trends in soil physicochemical properties and enzyme activity,while restoration of litter results in rising trends for both.Continuously removing litter from woody plots will cause rapid expansion of the Deyeuxia angustifolia population,accelerate the invasion process of Deyeuxia angustifolia,and although the woody plant Rhododendron aureum Franch also exhibit population growth,it is relatively slow.Removing litter from herbaceous plots will inhibit the growth of Deyeuxia angustifolia.In conclusion,litter fall from Deyeuxia angustifolia has a significant impact on native plants and their community structure,soil physical and chemical properties,soil enzyme activity,and soil microbial community structure and function.Litter removal cannot prevent the expansion of Deyeuxia angustifolia,especially in woody communities.Deyeuxia angustifolia can promote their own growth and expansion by affecting soil enzyme activity through their litter.