Studies On The Effects Of Different Diversity Combination Soils On The Growth Of Two Invasive Plants And Their Context Dependence

Biological invasion has caused serious damage to the natural environment and aggravated the deterioration of the ecological environment.In recent years,China has become one of the country’s most severely damaged by biological invasion in the world.The invasion of exotic plants has caused significant damage to China’s ecological environment and agricultural production.With the continuous deepening of research,the phenomenon of plant-soil feedback has gradually been recognized by the academic community as one of the important factors affecting plant growth.Based on the above background,this study takes plant soil feedback as the entry point,and adopts the method of artificial construction of soil communities composed of local common plants with different levels of plant diversity to explore the difference in response of two different types of ectomycorrhizal invasive plants(non-mycorrhizal plant Phytolacca americana and arbuscular mycorrhiza plant Rhus typhina)to the soil of different plant diversity communities.Combined with the structural changes of soil fungal community,the role of soil fungi in the impact of species diversity on invasion resistance was revealed.At the same time,we explored the impact of different environmental conditions(different nutrient levels,population density,and competition modes)on the process of soil microbial action,and clarified the context dependence of plant soil feedback.This study aims to answer the following two main scientific questions: 1 What are the effects of different diversity combinations of soil on the growth of invasive plants?What role do soil fungi play in it? 2.Are the above plant soil feedback processes affected by different environmental conditions such as nutrient levels,population density,and competition patterns?The research results show that:1.Compared with P.americana,the growth of R.typhina is more affected by the change of species diversity.Unlike the prediction of the diversity impedance hypothesis,soils with high local plant diversity are more favorable for R.typhina growth,and this change is regulated by soil fungi.The analysis of functional groups of soil fungi shows that with increasing diversity,there are significant changes in animal pathogens and arbuscular mycorrhizal fungi.Spearman correlation analysis showed that the growth performance of P.americana and R.typhina were significantly correlated with different fungal groups,respectively.Some genera of Rhodiola can enhance the absorption of phosphorus by P.americana,while Penicillium and Mortierella may promote the growth of P.americana by antagonizing pathogenic bacteria such as Fusarium.The growth of R.typhina is closely related to fungi such as Arthrospora,Tararomycetes,and Chaeatomium.They have biological control capabilities against soil nematodes or plant pathogens,and are also excellent plant growth promoters.2.Diversity did not affect the biomass accumulation of P.americana,and nutrient addition significantly promoted the growth of P.americana.As the density increases,the plant height of P.americana decreases,but the aboveground biomass increases.The biomass allocation indicators respond flexibly to changes in different environmental conditions.The impact of diversity on the growth of P.americana is influenced by nutrient levels rather than density,reflecting its ability to actively respond to nutrients and efficiently utilize them.There is also a certain interaction between nutrient and density on the growth of P.americana,mainly affecting its biomass allocation indicators.The above research shows that P.americana has good phenotypic plasticity,can flexibly adapt to the changing environment,make full use of the nutrient resources in the environment,which is conducive to overcoming the negative density dependence in population expansion and promoting the success of invasion.3.R.typhina grow best in soil with high plant diversity combinations.Nutrients alone have no significant impact on the growth of R.typhina,but the effect of nutrients is more significant in soil with high plant diversity combinations.Under different competition conditions,intra species competition is more conducive to the accumulation of biomass in R.typhina compared to inter species competition.There is an interaction between competition and diversity,which significantly affects plant height.In this study,biomass allocation indicators responded positively,reflecting the flexible phenotypic plasticity of R.typhina: it is more conducive to the development of its root system under low nutrient conditions,and in this way,it can seize resources needed for growth when nutrients are poor.When in nutrient rich soil,R.typhina tend to allocate resources to the aboveground parts to achieve increased biomass.The above growth strategies have promoted the invasion of R.typhina.Under intraspecies competition,plant growth performance is better than interspecies competition,indicating that Ailanthus altissima may play a role in the prevention and control of R.typhina to a certain extent.This study conducted a comparative study on two different types of invasive alien mycorrhizal plants,the P.americana and the R.typhina,to analyze the role of soil fungi in regulating the relationship between plant diversity and community invasiveness,and to confirm that the role of soil microorganisms is context dependent.This study has enhanced the understanding of the process and mechanism of biological invasion,and has certain guiding significance for the prevention and control of alien invasive species.