Characteristics Of Soil Physical And Chemical Properties And Microbial Community Change In Succession Process Of Fir Plantation After Cutting

Guanshan Nature Reserve is located in the west part of Jiuling Mountain,in Yifeng and Tonggu county,Jiangxi Province.The vegetation in the protected area shows a certain distribution.In this study,the natural broad-leaved forest,15-and 30-year fir plantation which are from natural forest after clear cutting,5-,15-and 25-year coniferous and broad-leaved mixed forest which are from fir plantation after selective cutting were used to study the response of forest vegetation,soil characteristic,microbial community structure and functional to the process of human disturbance and natural succession in the studying woodland and to determine the relationship among them.The aim of our study is to provide theoretical basis for protecting and improving the ecological benefits of forest land.The main research findings were:1.The plantation of fir plantatio after clear cutting of natural broad-leaved forest could significantly change the trees community composition,and then the vegetation community of fir plantation was relatively stable.However,the selective cutting will change the community composition of shrub and trees,and with the progressof natural succession the forest spatial is gradually optimized.After 25 years of selective cutting,the vegetation community was close to the natural broad-leaved forest.2.Fir plantation after the clear cutting of natural broad-leaved forest will increase the content of soil organic matter,while the soil physical and chemical properties of 15 and 30-year fir plantation are close.The selective cutting of artificial forest will significantly change the soil physical and chemical properties,after selective cutting 25 years the soil properties restore to the level of artificial fir before cutting.The factors that affect the soil physical and chemical properties were terrain and vegetation.3.The fungi and bacterial abundance of natural broad-leaved forest were higher than those of other forest types.It was also found that the structure and composition of the bacterial community after selective cutting had succeeded in the direction of fir plantation and after 25 years selective cutting can not make the composition of bacteria to restore the level of natural broad-leaved forest.For soil fungi,the selective cutting change the fungi community structure succession,but the succession direction is not the fir plantationbefore selective cutting and the original natural broad-leaved forest.At the same time,it was found that the strongest driving factor affecting the change of bacterial community structure was soil physical and chemical properties,and the main influencing factors of fungal community structure were tree community composition and soil physical and chemical properties.The main bacterial composition in the Guanshan Nature Reserve were Acidobacteria and Proteobacteria,and the abundance were 36.40% and 32.19%,respectively.There are no significant differences in bacterial composition among different forest land.The fungi were composed mainly of Ascomycota and Basidiomycota,with abundance of 44.70% and 52.59%,respectively.The relative abundance of Agaricomycetes increased during the natural restoration process,while the Sordariomycetes decreased gradually.4.When the natural broad-leaved forest was transformed into fir plantation,the activity of phenol oxidase was decreased and the ?-xylosidase and acid phosphatase were increased.With the increase of forest age,the ?-glucosidase and acid phosphatase activity of fir plantation decreased significantly.The activities of ?-glucosidase,acetylglucosaminidase,acid phosphatase and phenol oxidase were significantly increased during the natural succession of coniferous and broad-leaved mixed forest after selective cutting.Further studies have found that the main physical and chemical factors that affect the soil enzyme activity are soil organic carbon and pH.The plantation of fir plantatio after clear cutting of natural broad-leaved forest is not conducive to the restoration of ecosystems.However,the selection of artificial fir forest will significantly increase the diversity of vegetation and fungal communities,and will enhance soil enzyme activity.The results showed that the selective cutting was beneficial to the restoration of forest ecological environment,which was an important method to improve the ecological benefits of artificial fir forest.