The Feedback Of Soil Biota To Invasive Plants: Shift With Plant Species And Soil Heterogeneity

Soil microbe is of great importance factor which play a key role in invasiveness of exotic plant andinvasibility of ecosystem. The structure and function of soil microbe shift in the process of exotic plantsinvasion, these variation affects growth and competition of exotic plants in turn, which is a newmechanism of invasion for exotic plants-soil microbiology feedback mechanism. The interaction andfeedback between the invasive plants and soil microbial communities have a closely relationship withthe invasion mechanisms, which have become an international research focus and an important researchparts of exotic plant invasion biology. This study focuses on the feedback of soil microbe to exoticplants such as Ageratina adenophora, Ambrosia artemisiifolia, Flaveria bidentis, Bidens pilosa,compare the feedback of soil microbe to native and exotic plants which trained by themselves, the mainline of this study is exotic plant-soil microbe-native plant, we try to investigate the feedback of soilmicrobe to exotic plants and relationship with exotic plant species and soil heterogeneity. The mainresults are as follows:1. The feedback of soil microbe to the growth and competition of Ageratina adenophoraBy inoculation of soil microbe trained by A. adenophora and native plants soil, and treat withsterilization and fungicide to verify the soil microbe feedback on plant growth, we found plants biomassgrown in A. adenophora invaded soil is significantly greater than in native soil, and the soil fungalcommunities and AMF perform better in the A. adenophora soil. the phospholipid fatty acid analysis(PLFAs) results of microbial community structure showed that the fungicide treatment can effectivelyinhibit the soil and fungal community and AMF, A. adenophora invaded soil microbial community isapparently different from the native and fungicide treatment, the fungi and AMF content is12.5%and24.4%greater than the native soil, respectively.In order to investigate the role of microbe community functional species in the feedback to exoticplants, we inhibit the microbe community or fungal and bacterial communities by sterilization orfungicide and bactericide. We found that soil fungal community in A. adenophora soil can promotephotosynthesis of A. adenophora, photosynthesis of A. adenophora after addition of fungicide declineby28.5%, the photosynthesis of the native plants Rabdosia rebia significantly promoted by thefungicide and bactericide, the photosynthesis of R. rebia increased by42.5%and45.6%after additionof fungicide and bactericide respectively. The soil microbe community altered by A. adenophora canpromote the biomass, photosynthesis and plant physiological makeup of A. adenophora, but usuallyhave no significant effect on other plants, and promote the growth of A. adenophora when competitionwith other plants.2.Tthe feedback of the soil microbe of different exotic plants–plant species differencesAfter understanding the soil microbe feedback effects to invasive plants, we analyzed a number ofexotic and native plants soil trained by3years in the field plant homogeneity garden plot experiment,and found that samples of physical and chemical properties and microbial community in different plant rhizosphere soil changed significantly, the exotic plants, such as Ambrosia artemisiifolia, Flaveriabidentis, Bidens pilosa, their soil pH value is significantly lower compared to the local plant, soil N, P,K and other nutrients are also different from the local, and PLFAs results show that invasive plants canform their unique characteristics of soil microbial communities and functional groups.We conduct greenhouse feedback experiment using soil collected from the plant homogeneity plot,we found that exotic plants grow in their own and foreign soils are apparently different. F. bidentisbiomass decrease by42.1%in the own than in foreign soil, B. pilosa increase by13.4%, but A.artemisiifolia has no significant difference. This indicates that the different soil microbial feedback toplant is related to the plant specificity; consider with the local plant Lin Zelan feedback growth indifferent soils, invasive plant soils are favorable for its growth compared to native soils, it biomassincrease about38.6%,17.8%and44.5%than in local soil, respectively, while native plants soils haveno significant impact. Competition between invasive plants A. artemisiifolia and native plants in furtherindicate that: the local soil microbial communities and different groups (groups such as fungi or bacteria)have the same degree of influence to A. artemisiifolia and native plants, but soil invaded by A.artemisiifolia can significantly affect the outcome of competition between A. artemisiifolia and nativeplants.3. The different feedback of soil microbe to exotic plants in different habitats-soil heterogeneityTo investigate the inherent relationship between the soil microbial feedback and habitat heterogeneity ofthe soil, we sampled three kinds of soil that different in fertility and soil microbial communities indifferent habitats (barren mountain, weedy roadside, rich fertility farm) to see how soil microbe affectsthe seed germination, seedling growth, as well as competition of invasive species and native plants.The results showed that: the soil can affect seed germination, soil microbe in different habitats havedifferent feedback effect on seed germination rate or different species. Mountain habitats have nosignificant effect on seed germination because of its relatively poor soil and soil microbe; Farm soilhave rich fertility and high levels of pathogens, significantly inhibit the germination rate ofChrysanthemum seticuspe, Achyranthes bidentata and B. pilosa, the germination rate increase about393.8%,134.5%and366.7%after sterilization, while the germination rate of A. adenophora decreaseabout61.36%after sterilization. The soil from the roadside also have effect on A. adenophora and A.bidentata, their seed germination rate decrease or increase by48.53%and211.1%, respectively.Seed germination rates of plant species in different habitats are variable between plant species, whichcan explain the phenomenon that diversity and richness of plant species in different habitats. In thisexperiment, the soil microbes of different habitats can promote seed germination of A. adenophora, buthave neutral feedback or negative feedback to other plants, this is one reason for A. adenophorapopulation have strong invasiveness and can spread rapidly.Soil microbe feedback experiment on the different types of habitats found that, soil microbecommunities in different habitats show different feedback effects on invasive plants-soil heterogeneity.For example, mountain soil microbe communities have positive feedback to all the plants except A. bidentata, and farm soil have negative feedback for all plants, their biomass increase significantly aftersterilization, but the roadside habitats soil have different feedback, depending on the plant species. Soilmicrobes in different habitats will have different feedback effects on the competition between invasiveplants and native plant, soil microbial communities of different habitats will increase or decrease of therelative dominance of invasive plants, and therefore affect competition results.4. ConclusionFeedback of a variety of invasive plants and soil microbe interactions indicates that invasive plants canchange the soil microbe community structure and soil microbe in turn will directly invade the plantgrowth and competition, different soil microbe communities have different feedback. Depending on thedifferences of exotic plants, the soil microbe feedback is apparently different, and produce differenteffects on plant growth and competition of invasive plants. soil microbe communities of differenthabitats invasive plants show different feedback, have a direct impact on the seed germination, growthand competitive process of invasive plant, these are the feedback of soil microbe feedback influenced byplant species and soil heterogeneity. The knowledge and study on this feedback effect of soil microbe toexotic plants is significancantly helpful for us to realize the knowledge of exotic plant invasionmechanism comprehensively, and propose the strategy of invaded ecological restoration.