Study On The Effect Of Bamboo Forest Expansion On Microorganisms Involved In Soil Carbon Cycle By DNA-SIP

The soil carbon cycle is the core of the element cycle of the soil ecosystem,and it is also the driving factor of the soil nitrogen,sulfur and phosphorus cycles.The study of changes in soil microbes caused by changes in forest vegetation,microbes will change the cycle of elements in the underground soil,is of great significance to global environmental governance.Bamboo has a high economic value.According to incomplete statistics,the area of bamboo forests in my country is increasing at a rate of about 3%per year,and the expansion area reaches as much as 50,000 hectares,which has a serious impact on the surrounding forest ecosystem.This study attempts to study the impact of bamboo forest expansion on the structure and function of soil microbial communities from the perspective of carbon cycle,to provide data for the scientific management of bamboo forest ecosystems,and to provide a basis for the management of other invasive plants.In this study,three forest types including purely artificial bamboo forests in Miaoshanwu Nature Reserve,Zhejiang Province,subtropical secondary evergreen broad-leaved forests invaded by bamboos,and subtropical secondary evergreen broad-leaved forests were used as the research objects,using DNA-SIP(DNA-stable isotope probing)technology detects the relative abundance of 16S and ITS genes involved in the carbon cycle in different buoyancy density levels,analyzes and screens the ¹³C-DNA enrichment positions after ¹³C-starch labeling,and combines with Qualcomm Quantitative sequencing(16S?ITS)technology is used to study the composition of microbial communities involved in the soil carbon cycle.At the same time,this research also carried out filtration and separation of roots,mycorrhizas,and microorganisms through different mesh sizes to explain how soil microorganisms participate in the process of soil carbon cycle under the action of roots and mycorrhizas,and provide science for the study of bamboo forest expansion.The theory provides a basis for the development and utilization of bamboo resources.The main research results and conclusions are as follows:In this study,the pure moso bamboo forest,the evergreen broad-leaved forest invaded by moso bamboo,and the broad-leaved forest,as well as the 16 S gene and ITS gene of different soil biological components,were marked and separated to different degrees.The main phyla and relative abundance of bacteria in the soil rhizosphere carbon turnover bacteria in the broad-leaved mixed forest formed after the expansion of the bamboo forest changed,but not significant.The relative abundance of the main bacterial genera changed significantly.The three woodlands belonged to the genera.There are significant differences in the level of classification,and the carbon cycle bacteria that play an important role are different.The total number of species and community diversity of the pure Phyllostachys pubescens forest is the highest.The soil carbon cycle bacterial community structure of the Phyllostachys pubescens forest and the mixed forest are similar,the soil carbon cycle bacterial community structure of the broadleaved forest and the mixed forest are similar,and the soil carbon cycle of the Phyllostachys pubescens forest and the broad-leaved forest are similar.There are significant differences in bacterial community structure.In the process of invading broad-leaved forests,bamboo forests can gradually change the function of soil ring bacterial community and realize the invasion by making the community structure of the soil carbon cycle bacteria in the invaded area succeed.The soil carbon cycle fungi in the expansion of the bamboo forest have relatively few clusters at each taxonomic level.The relative abundance of species at the phylum and class level has changed,but it is not obvious.Compared with the three forest types,only the soil of the bamboo forest and the broad-leaved forest has The fungus genus that plays an important role in soil carbon cycling,the change of this genus may determine the success of the moso bamboo forest invasion.The role of roots and mycorrhizas changes the relative abundance of the main phyla and classes of bacteria and fungi in the soil rhizosphere carbon turnover in the expansion area of Phyllostachys pubescens.There are only roots and mycorrhizas in the soil with three different biological components.Important role of carbon cycle bacteria,there is no important role of fungi,the role of mycorrhiza,roots can change the soil texture by changing the soil bacterial community.The simultaneous action of roots and mycorrhizas increases the species diversity of soil rhizosphere carbon turnover bacteria and the Shannon index in the expansion area of Phyllostachys pubescens,which makes fungi decline;the role of mycorrhiza makes the soil rhizosphere carbon turnover bacteria and fungi in the expansion area of Phyllostachys pubescens forest.Species diversity and Shannon's index rose.This study showed that the expansion of bamboo forests caused changes in the total number of soil microbial species and community diversity,which in turn caused changes in the functions of related communities.In the process of community change,plant roots and mycorrhizal colonization will affect the total number and diversity of microbial species.In this study,the number of bacteria in the soil carbon cycle clustered to the phylum level is far more than that of fungi,and the soil carbon cycle may be mainly driven by bacteria.The microbiological mechanism of bamboo expansion: On the one hand,bamboo improves its competitiveness by increasing the abundance of microorganisms that is conducive to the acquisition of soil nutrients;on the other hand,it reduces the absorption of bacteria and fungi related to nutrients by zonal tree species to weaken the effect of zonal tree species.The ability to obtain nutrients can explain the research on the greater impact of bamboo forest expansion on forest ecosystems from the perspective of underground soil microorganisms and element cycles.