Dynamic Characteristics Of Community And Soil During The Shrubment Of Stipa Bungeana Community In Ordos Plateau

Grassland shrubbery has destroyed the structure and function of the grassland ecosystem.Increase the spatial heterogeneity of soil,Finally,it may lead to land degradation and desertification.The phenomenon of shrubbery has occurred all over the world.The succession of community and soil in the background of shrubment in China is still insufficient.Based on the shrub grassland of Stipa bungeana and Artemisia annua in the Ordos Plateau,this study analyzed the community characteristics and the changing trend of soil physical and chemical properties in succession,which provided a theo retical basis for the restoration of grassland shrub.Using space-time intergeneration method,Selection of six representative succession Stage in the shrub grassland of Stipa bungeana on Ordos Plateau,The total coverage,total density,litter coverage,biom ass and important values of different succession stages,as well as the coverage,density and importance value of main species in the community were analyzed.The changes of plant roots and species diversity in the community were also studied.The results s how that:(1)The main six stages in the process of community succession,respectively,Stipa bungeana Communities,Stipa bungeana + Artemisia ordosica Communities,Artemisia ordosica + Cleistogenes squarrosa communities,Artemisia ordosica + Lespedeza davurica communities,Artemisia ordosica communities..The succession stage consists of 26 plants,including 4 species of shrubs,respectively,Artemisia ordosica,Caragana,Yang Chaiheda daurica herbaceous plant more.The species composition of the community showed a trend of increasing and then decreasing.(2)Six successional stages in the vegetation coverage fluctuations,the overall changes firstly decreased and then increased.The litter coverage increased gradually,bu t the differences in each stage were not significant.The total density of community has a decreasing trend as a whole.The first five stages of change are relatively small,and there is a rapid decline in the VI stage.The dry weight of litter in the comm unity increased steadily.The coverage,density,biomass and important value of Stipa Beni continued to decrease in the main plants of the six succession stages,while the Artemisia Artemisia was the opposite.The variation trend of other species in the community was increased first and then decreased,and the maximum value appeared in the IV stage.In the course of succession,the species diversity of community species increased and then declined,and the maximum value appeared in the II and IV stages,and the difference was significant.(3)Plant community succession process change and distribution with the succession of changes in the VI stage,decreased,the VI phase change increased first an d then decreased,but the whole process of succession of root distribution gradually deepened,at the stage of VI,root depth can reach 80 cm.(4)There were significant differences in soil physical and chemical properties in six successional stages.Soil texture changed from loam sandy soil to sandy soil,and soil cl ay content gradually decreased,while sand content increased.The soil water content has a downward trend in general,and the soil bulk density has a rising change,and the soil is more and more tight.All the soil total carbon,total nitrogen and total phosphorus decreased in the course of succession,but the total K of soil fluctuated greatly,and there was a slight increase.It can be seen that there are significant differences in community characteristics and soil structure with the intensification of Stipa bungeana and Artemisia grassland.Though the community coverage,biomass and species diversity were relatively high during the middle shrub,the shrub invasion would destroy the original vegetation types and reduce the grazing value of the grassland.Therefore,the shrub grassland should be restored to the main grassland of Stipa bungeana.