Study On Diversity And Influencing Factors Of Arbuscular Mycorrhizal Fungi In Rhizosphere Of Tetraena Mongolica

Tetraena mongolica Maxim,which is an endemic relict shrub of Tetraena in zygophyllaceae,only survives and patchness distributes in the western ordos desert.In order to study the co-evolution mechanism of Tetraena mongolica and AM fungal,and the AM fungal diversity in desert ecosystem,Hainan district(S1),Qianli mountain(S2)and Balagong(S3)three sample sites were chosen in this study.The AM fungal community's composition,structure and distribution charcteristic of Tetraena mongolica population were studied.The correlations between the AMF species diversity with the plant community and soil factors have been analyzed.Main conclusionsare as following.1.The population density of Tetraena mongolica was 5.7?21.3 per 100m2.This significantly declines in the order of S1,S2 and S3(P<0.05).Plant height was 30.7?44.1 cm,ground diameter was 7.25?8.19 mm.The above indexes in S2 are significant lower than S1 and S3,and there was no significant difference between S1 and S3.The abundance of Tetraena mongolica was 0.033?0.378,relative density was 0.24%?4.6%and the important value was 0.313?0.825.The importance of this population in plant community locating in S2 was significantly higher than both S1 and S2(P<0.05).In addition,the importance in S3 was significantly lower than in S3(P<0.05).The Shannon-Weiner index of shrubs and herbaceous community were 0.850?1.264 and 1.145?1.778,respectively.The Simpson's index of shrubs and herbaceous community were 0.447?0.679 and 0.626?0.771,respectively.2.Soil moisture content was 0.54%?2.95%,pH-value was 8.28?8.53,the content of ammonium nitrogen,rapid available phosphorus and available potassium were 46.67?93.78 ?g/g,34.67?113.33 ?g/g,8.778?70.333 ?g/g,respectively.The content of total nitrogen,total phosphorus and organic matter were 0.126?0.315 mg/g,0.174?0.212 mg/g,3.003?8.203 mg/g,respectively.All these indexes changes varies as the soil layer goes deeper.Moisture,rapid available phosphorus and organic matter were significantly reduced(P<0.05)in the order of S1,S2 and S3.3.The soil enzymes activities were as following:urease activity was 0.211?0.610 NH3-N mg/g,nitrate reductase activity was 3.513?5.06 NO2-mg/g,acid phosphatase,neutral phosphatase,alkaline phosphatase activities were 0.017?0.033,0.012?0.026,0.009?0.039 phenol mg/g,respectively.Sucrase activity was 2.839?12.820 reducing sugar mg/g,cellulase activity was 45.945?71.843 glucose mg/g and polyphenol oxidase activity was 28.831?49.393 violet Gallocatechin mg/g,All these enzymes activities changes varies as the soil layer goes deeper.The activities of alkaline phosphatase and sucrose were significant reduced(P<0.05)in the order of S1,S2,S3.4.27 species of AM fungi which belong to eight genus were isolated from the rhizosperic soil of Tetraena mongolica.6 species belong to Acaulospora,3 species belong to Claroideoglomus,1 specie belongs to Diversispora,2 species belong to Funneliformis,9 species belong to Glomus,3 species belong to Rhizophagus,2 species belong to Septoglomus,and 1 specie belongs to Scutellospora.The dominant species were A.sp1,A.sp2,C.claroideum,C.etunicatam,D.spruce,G.hyderolabadensis,G.versiforme,G.macrocarpum,R.intraradices,S.constrictum,S.deserticola.5.In 50g soil sample,AM fungal spore density was 23.3-156.3,the spore density increases while the soil layer goes deeper.AM fungal species richness was 8.7-15.0 species,this index increases as the soil layer goes deeper in S1 while the situation is opposite are S2 and S3.AM fungal community's Shannon-Weiner indexes and Simpson's indexes were 1.389?2.192 and 0.596?0.840,respectively.Both indexes decreased in the order of S1,S3 and S2.6.There was a significant positive correlation between both AM fungal spore density and species richness and the indexes including Tetraena mongolica population features,shrubs community's Shannon-Weiner indexes and Simpson's indexes,soil moisture content,soil nutrient content,soil alkaline phosphatase and sucrase activities(P<0.05).AM fungal community's Shannon-Weiner indexes and Simpson's indexes of 30-40 cm soil layer had a significant positive correlation with herbaceous community's Shannon-Weiner indexes,Simpson's indexes and soil moisture content(P<0.05).However,AM fungal community's Shannon-Weiner indexes and Simpson's indexes of 30-40cm soil layer had a significant negative correlation with available potassium content and soil urease activities(P<0.05).