Nutrition And Soil Microbiological Characteristics Of Invasive Plant Of Eucalyptus Plant In Guangxi

Eucalyptus has many advantages,such as barren tolerance,high growth rate and wide application.Because of its high growth rate and excessive consumption of soil fertility by nutrient utilization rate,as well as the allelopathy of roots and other factors.At the same time,Eucalyptus plantation has the characteristics of low diversity and easy invasion by exotic plants.At present,the effects of invasive plants on habitat and tree growth in eucalyptus plantation are uncertain.Therefore,this study explores the effects of invasive plants on soil nutrients and tree growth from the aspects of plant nutrition and soil microbial characteristics,as well as the similarities and differences of root zone microorganisms under invasive species,native species and eucalyptus species,in order to answer whether invasive species under eucalyptus plantation are harmful to tree growth and soil environment,and puts forward some rational suggestions for eucalyptus plantation management.The sample site of this study is located in Xiaolin Town,Longan County,Guangxi.The main invasive species are Bidens pilosa and Chromolaena odorata,local species are Microstegium fasciculatum and others.In the experiment,three kinds of communities were selected,and the dominant species of herbs in each field were Bidens pilosa and Chromolaena odorata and local species,respectively.This study was divided into two parts.The first one was to investigate the biomass of various plots and collect the samples of dominant herbs and eucalyptus species in each plot,as well as the soil in the root zone of herbs and eucalyptus.the carbon,nitrogen,phosphorus,potassium,calcium and boron contents of these samples were determined.The other part took fresh soil from the root zone of Bidens pilosa,Chromolaena odorata,native species and eucalyptus for high-throughput sequencing of microorganisms in the samples using Illumina Mi Seq gene sequencing platform.The results were as follows :(1)The invasion of a Bidens pilosa and Chromolaena odorata in eucalyptus plantation did not have a significant effect on the growth of trees.(2)The root zone nutrient level of Bidens pilosa and Chromolaena odorata was higher than that of eucalyptus and native species.The invasion of Bidens pilosa and Chromolaena odorata under eucalyptus forest crowded out the living space of local weeds,promoted soil fertility.(3)The microbial biomass of eucalyptus rhizosphere soil was significantly lower than that of three herbaceous plants(local species,Bidens pilosa and Chromolaena odorata)(p<0.05).(4)There was no significant difference in soil microbial diversity under the root zone of these species,and the main microbial groups were Proteobacteria,Actinobacteria,Acidobacteria,Chloroflexi,etc.Some specific species exist,but the contents are very low.(5)The contents of Rhizobia and Nitrifying bacteria were higher in the root zone under Bidens pilosa and Chromolaena odorata than those in native species.Multiple rhizobiums,such as Bradyrhizobium,Agrobacterium,Mesorhizobium,Rhizobium,were found in the samples.These nitrogen-fixing strains in the root zone under Bidens pilosa and Chromolaena odorata were higher than those in native species and eucalyptus species.Which implicated that the co-occurrence of Bidens pilosa and Chromolaena odorata with eucalyptus plantation could play the role of nitrogen fixation.