【作者】 周文；

【导师】 刘万学；

【作者基本信息】 中国农业科学院 ， 生物安全， 2012， 硕士

【摘要】 土壤微生物是影响外来植物入侵力和生态系统可入侵性的一个重要因素，在外来植物的入侵进程中起到十分重要的作用。外来植物入侵引起入侵地土壤微生物群落结构和功能的变化，这种变化反过来对入侵植物的生长及入侵植物与当地植物的竞争产生影响，这是外来植物入侵的一种新机制－土壤微生物学反馈机制。外来入侵植物与土壤微生物群落之间的互作及反馈与外来植物的入侵机制联系紧密，目前已成为外来植物入侵生物学研究的重要内容和国际研究热点。本研究从土壤微生物对外来植物的反馈作用入手，以紫茎泽兰、豚草、三叶鬼针草和黄顶菊等多种入侵菊科植物为研究对象，分析本地植物土壤微生物以及外来植物入侵后改变的土壤微生物群落及不同微生物类群对入侵植物和本地植物的生长及竞争的反馈影响，以入侵植物-土壤微生物-本地植物的互作关系为主线，综合阐述土壤微生物对外来植物入侵的反馈，分析反馈作用与入侵植物的物种差异性、土壤异质性之间的关联及规律。主要结果如下：1、土壤微生物对紫茎泽兰生长及竞争的反馈作用通过接种紫茎泽兰入侵土壤和本地植物土壤，采用湿热灭菌处理或添加杀真菌剂处理的方法，以此验证入侵植物土壤和本地植物土壤微生物对植物生长的反馈差异。结果发现紫茎泽兰入侵后土壤的微生物群落相比于本地植物土壤的微生物对植物的生物量有更明显的促进作用，紫茎泽兰土壤中的真菌群落对植物的有利反馈作用更强，土壤中的AMF群落侵染也更为有效。对紫茎泽兰土壤和本地植物土壤及两种土壤杀真菌剂处理后的土壤微生物群落结构进行磷脂脂肪酸分析（PLFAs）的结果表明，杀真菌剂处理能有效地抑制土壤中的丛枝菌根真菌和真菌类群含量，同时紫茎泽兰土壤和本地植物土壤及两者添加杀真菌剂后的土壤微生物群落结构明显不同，紫茎泽兰土壤中的丛枝菌根真菌含量比本地植物土壤中的丛枝菌根真菌含量增加24.4%，真菌含量增加12.5%。通过灭菌处理、添加杀真菌剂或杀细菌剂抑制紫茎泽兰重度入侵土壤中真菌或细菌群落，以此探究入侵植物紫茎泽兰土壤中各微生物类群对于紫茎泽兰生长及竞争时的反馈功能。研究发现，紫茎泽兰土壤真菌群落对紫茎泽兰的光合作用具有促进作用，添加杀真菌剂后紫茎泽兰的光合作用下降28.5%，而紫茎泽兰重度入侵土壤中的真菌和细菌群落对本地植物香茶菜的光合作用均具有明显抑制作用，杀真菌剂和杀细菌剂处理后，香茶菜的光合作用分别上升了42.5%和45.6%。紫茎泽兰改变的土壤微生物群落，尤其是真菌群落，对紫茎泽兰的生物量、光合作用和植株生理形态指标等都有明显的正反馈作用，而对其它植物则大多无明显影响，同时在紫茎泽兰与本地植物竞争时对紫茎泽兰产生偏利反馈影响。2、土壤微生物对不同入侵植物反馈的差异-物种差异性明确了土壤微生物对入侵植物的反馈影响后，我们通过野外基地的植物同质园小区试验，对多种入侵植物和本地植物种植三年后的土壤样品进行分析，发现不同植物根际周围土壤的理化性质和微生物群落发生明显改变，豚草、黄顶菊和三叶鬼针草等入侵植物的土壤pH值相比于本地植物马唐或小藜显著降低，土壤中N、P、K等营养元素也与本地植物存在明显差异，同时PLFAs的结果显示入侵植物能形成各自特有的土壤微生物群落特征，根际土壤微生物功能类群也有所差异。采集植物同质园小区中植物种植后的土壤进行温室盆栽反馈试验，我们发现入侵植物在自身土壤和其他植物土壤中的生长会受到不同的反馈影响，表现为黄顶菊在自身土壤相比于其他植物土壤中表现为负反馈，生物量显著降低42.1%，三叶鬼针草在自身土壤中表现为正反馈，生物量显著提升13.4%，而豚草则无明显差异。这说明不同入侵植物的土壤微生物反馈存在差别，即土壤微生物反馈具有物种（不同植物物种）特异性；结合本地植物林泽兰在不同土壤中的反馈生长来看，入侵植物改变的土壤微生物对它的生长有利，在豚草、黄顶菊和三叶鬼针草土壤中生物量相比于本地植物混生土壤中生物量分别增加38.6%、17.8%和44.6%，而本地植物改变的土壤微生物对它的生长则无明显影响，这可能从一方面说明入侵植物改变的土壤微生物群落能对植物产生更为有利的反馈。进一步通过入侵植物豚草与本地植物的竞争可以看出：本地土壤中的微生物群落及不同类群（如真菌或细菌类群）对豚草和本地植物的影响程度相同，对豚草与本地植物竞争时的相对优势度并没有明显影响，而豚草入侵后的土壤微生物则能够明显影响豚草的生长竞争反馈结果。3、不同生境土壤微生物对入侵植物反馈的差异-土壤异质性为了探究土壤微生物反馈与生境土壤的异质性之间的内在关联，我们比较研究了3种肥力和土壤微生物群落各异的土壤生境（贫瘠干旱的山地、多杂草丛生的路边、肥力丰富的菜地）的土壤微生物对多种入侵植物和本地植物的种子萌发、幼苗生长以及入侵植物与本地植物竞争互作的影响。试验结果表明：土壤微生物能够影响植物种子萌发，不同生境中土壤微生物对植物种子萌发率的反馈影响程度有所不同，对不同植物的影响也存在着种类差异性。山地生境由于其土壤较贫乏，土壤微生物总量和多样性较少，对植物种子萌发不存在明显的影响；菜地土壤中微生物种类丰富，病原菌含量高，甘野菊、牛膝和三叶鬼针草的萌发率明显受到抑制，灭菌处理使萌发率分别提升393.7%、134.5%和366.7%，表现为土壤微生物的负反馈影响，但紫茎泽兰则受到土壤微生物的正反馈影响，灭菌后萌发率下降61.4%。同样路边生境土壤微生物对于牛膝种子萌发存在负反馈影响，灭菌后萌发率提升211.1%，对紫茎泽兰种子萌发存在明显的促进作用，灭菌后萌发率下降48.5%。不同生境土壤中植物种子萌发率因植物种类而有所差异，这也能从一方面解释不同生境中植物的种类多样性和丰富度存在差异。本试验中，不同生境的土壤微生物对其他植物都具有中性反馈或不利反馈，对紫茎泽兰却表现为有利的促进作用，也从一方面解释入侵植物紫茎泽兰种群扩散迅速、入侵力强的原因。对不同类型生境土壤微生物反馈研究发现，不同生境中的土壤微生物群落对入侵植物表现出不同的反馈影响-即土壤异质性。如山地土壤中的微生物群落对除牛膝外的其它植物的生长都表现为正反馈，灭菌后生物量有所降低，在菜地生境中则土壤微生物对所有植物均为负反馈，灭菌后生物量显著增加，路边生境的土壤微生物反馈作用因植物不同而出现差别；同时不同生境中的土壤微生物也能通过对植物产生不同的反馈影响植物间的竞争，在入侵植物和本地植物竞争时，不同生境的土壤微生物群落会对入侵植物和本地植物产生不同的反馈影响，提升或降低入侵植物的相对优势度，产生不同的竞争结果。4、结论对多种入侵植物与土壤微生物的反馈互作表明，入侵植物能够改变土壤中的微生物群落结构，而土壤微生物会对入侵植物的生长和竞争产生直接的反馈作用，不同的土壤微生物类群产生的反馈影响和作用程度存在区别。取决于入侵植物种类的差异，受到的土壤微生物的反馈也不同，对入侵植物的生长和竞争也会产生不同的影响，即土壤微生物对植物的反馈存在物种差异性；同时不同生境的土壤微生物群落对入侵植物表现出不同的反馈，对入侵植物的种子萌发、生长和竞争过程产生直接影响，即土壤微生物对植物的反馈存在土壤异质性。土壤微生物对外来入侵植物存在直接反馈，同时物种差异性和土壤异质性因素影响着反馈效果，关于这种反馈规律的认知和相关研究，对我们全面和深入认识外来植物的相关入侵机理，提出和完善外来植物入侵生境的生态修复策略，具有直接的理论意义和参考价值。更多还原

【Abstract】 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.更多还原