【作者】 李会娜；

【导师】 曹远银； 万方浩；

【作者基本信息】 沈阳农业大学 ， 有害生物与环境安全， 2009， 博士

【摘要】 外来植物与土壤微生物的互作关系是外来植物入侵机制研究中的一个热门问题。本研究以我国典型的入侵菊科植物紫茎泽兰（Eupatorium adenophorum（Sprengel）R.King&H.Robinson（Synonym:Ageratina adenophora））、豚草（Ambrosia artemisiifolia,L.）和黄顶菊（Flaveria bidentis L.）为研究对象,在其入侵地野外调查取样研究的基础上,探讨了外来菊科植物入侵对入侵地土壤微生物群落结构的影响以及由此引起的对外来植物和伴生植物生长的反馈作用:并通过同质园模拟试验,解析了3种入侵菊科植物与土壤微生物的互作关系。研究结果表明:1.紫茎泽兰显著改变了入侵地的土壤微生态环境,大幅度提高了土壤中植物可直接吸收的硝态氮、铵态氮、有效磷、速效钾和有机质含量。重度入侵生境中铵态氮含量最高达53.00mg/kg,分别为裸土土壤、混生本地植物土和单一本地植物土壤的14.1、9.9和5.9倍。硝态氮含量随入侵程度加深呈增加的趋势,且在不同入侵程度的土壤中差异显著,重度入侵区土壤中硝态氮含量为91.98mg/kg,为裸土土壤的7.3倍。微生物可培养结果显示在重度入侵区土壤真菌、自生固氮菌、氨氧化细菌数量均较高,DGGE分析结果表明紫茎泽兰入侵降低了菌根真菌的多样性,破坏了当地植物菌根真菌群落的组成。杀菌剂控制的盆栽试验验证了这种改变可以帮助紫茎泽兰与当地植物竞争,对紫茎泽兰自身生长有利,而对伴生植物的生长不利。2.豚草不同入侵程度的土壤微生态发生了显著变化,其中重度入侵区土壤有效氮和有效磷的含量分别为12.79mg.kg^-1和32.98mg.kg^-1,分别是当地植物区对应含量的2.4倍和1.9倍;有效钾的含量为93.8mg.kg^-1,是当地植物区对应含量的2.7倍。PLFA指纹图谱表明豚草不但显著改变了入侵地的土壤微生物PLFA含量,而且还能显著改变微生物群落结构,尤其是显著降低了真菌的含量。温室盆栽灭菌试验发现豚草入侵地的土壤微生物群落抑制了伴生植物的生长,显著增强了豚草的生长和竞争能力。3.采用PLFA方法比较了黄顶菊不同入侵地土壤微生物群落,结果显示,黄顶菊显著改变了入侵地的土壤微生物群落结构,尤其是提高了表征菌根真菌的16:1ω5脂肪酸的含量。黄顶菊与本地植物小藜及马唐的同质园基地竞争模拟试验结果显示,马唐与黄顶菊竞争时的生物量仅为马唐单独生长时的61%,说明黄顶菊的存在显著抑制了马唐的生长,同时,黄顶菊与小藜的竞争对小藜生长的抑制作用也达到了显著水平。4.同质园模拟试验结果显示:三种入侵菊科植物和本地植物分别对土壤微生态产生了不同程度的影响。盆栽反馈试验结果表明,三种入侵植物生长过的土壤对旱稻都有一定的抑制作用,不利于旱稻的生长。土壤灭菌处理后,黄项菊生长过的土壤使旱稻株高增加了113%,豚草生长过的土壤使旱稻株高增加了83%,紫茎泽兰也使旱稻的株高增加了17%。三种入侵植物生长过的土壤对紫花苜蓿也存在一定的抑制作用,土壤灭菌处理后,紫茎泽兰生长过的土壤使紫花苜蓿的根长增加了36%,黄顶菊生长过的土壤使紫花苜蓿的根长增加了14%,豚草生长过的土壤对紫花苜蓿的根长影响不显著（F₁=2.96,P=0.1018）。以上结果揭示外来菊科植物可能通过改变入侵地土壤微生物群落,破坏当地植物生长的土壤微环境,为自身生长创造了有利的土壤微环境。更多还原

【Abstract】 The interaction between invasive plants and soil microorganisms has been paid more attention by scientists in the area of the invasion mechanisms of alien plants.Three Chinese typical invasive composite plants,i.e.Ageratina adenophora（Sprengel）,Ambrosia artemisiifolia L.and Flaveria bidentis were taken as examples to study their effects on the diversity and structure of invaded-soil biota and the feedbacks caused by them to the growth of receptor plants.Meanwhile,common garden experiments were conducted in order to elucidate the interaction between staple invasive composite plants and soil microbial communities.The main results were as follows:The micro-habitat of the invaded-soil was changed greatly and the content of absorbable NO₃^--N,NH₄⁺-N,available P and K,organic matter in soil were increased sharply.The highest amount of NH₄⁺-N in heavily invaded soil reached 53.00mg/kg,which was almost 14.1,9.9 and 5.9 times each as high as bare soil,multi-native-plants soil and single-native-plant soil,respectively.The content of NO₃^--N in soil had a tendency to increasing with the intensification of invasion and was different significantly among soils with various invasion degree.The amount of NO₃^--N in heavily invaded soil,with the content of 91.98mg/kg,was as nearly 7.3 times as that in bare soil.There was an obvious correlation between the change of soil enzyme activity and the alteration of soil physical and chemical properties and the change of soil microbial communities and enzyme activity in turn might lead to the modification of soil nutrient condition.The number of soil fungi,azotobacteria and ammonia oxidizing bacteria in heavily invaded site was comparably high as testified by the results of the DGGE analysis.The diversity of AMF was reduced and the structure of AMF communities in native plants was damaged following the invasion of A.adenophora,which could explain the advantages of A.adenophora in competition with native plants via greenhouse pot experiments controlled by fungicide. The micro-habitat of soil with different level of invasion by A.artemisiifolia also altered greatly.The content of soil available N,P and K content reached 12.79 mg.kg^-1,32.98 mg.kg^-1 and 93.8mg.kg^-1 each in heavily invaded sites,which were almost 2.4,1.9 and 2.7 times as high as soil collected from native region.The PLFA fingerprint spectrum indicated that not only the amout of PLFA extracted from soil microorganisms in invaded site was changed significantly,the structure of soil microbial communities was altered obviously,with the decreasing of soil fungi.Greenhouse sterilized pot experiments found that the altered microbial communities in invaded soil by A.artemisiifolia facilitated the growth of A. artemisiifolia but inhibited native species.The soil microbial communities in various invasive habitats of F.bidentis were compared through the method of PLFA analysis.The result showed that the structure of soil microbial communities was changed significantly in invaded area,with improving the content of 16:1ω5 fatty acid of token AMF.The result of the competition between F.bidentis and native plants Chenopodium serotinum L.and Digitaria chinensis Homem.simulated by common garden experiment demonstrated that the biomass of D.chinensis in competion with F.bidentis was 61%that of D.chinensis grown alone,which indicated that the presence of F.bidentis inhibited the growth of D.chinensis greatly and the inhibition effect on the growth of C. serotinum was obvious.The results simulated of common garden simulating experiments suggested that three invasive composite plants and native plants had exerted different influences on soil micro-habitat.The results from pot feedback experiment showed that the soil invaded by the three invasive plants had inhibited the growth of oryza sativa.The plant height of oryza sativa increased by 113%,83%and 17%respectively when it was cultivated in sterilized soils invaded by F.bidentis,A.artemisiifolia and A.adenophora.Soil invaeded by invasive plants also had an inhibitive effect on the growth of Medicago sativa L.After sterilization,root length of M.sativa increased by 36%and 14%,respectively,when it was grown in A. adenophora and F.bidentis invading soils but influence was not significant while grown in A. artemisiifolia invading soil（F₁=2.96,P=0.1018）. In conclusion,the above results suggested that the invasive composite plants might destroy the soil micro-habitat of native plants and create new one favourable to the gowth of the invasive plants through alteration of soil microbial communities.更多还原