Study On The Composition Characteristics Of Clay Minerals In Forest Soil Under Different Climate Zones

Forests,as the largest ecosystems on land,have brought important material foundations for people's survival and development.In this paper,forest soils in seven different climatic zones(cold temperate zone,mid temperate zone,warm temperate zone,northern subtropical zone,central subtropical zone,southern subtropical zone,tropical zone)were studied,The variation characteristics of soil clay were studied in many aspects and on a large scale in order to provide reference for soil improvement and forest ecosystem maintenance.This study from different climatic zone of forest soil clay mineral characteristics,the determination of particle composition,chemical composition of the tested soil characteristics,on the basis of using X-ray diffraction(XRD)analysis method,analysis of different forest soil clay minerals XRD phase characteristics,explore different climatic zone of forest soil formation and content of clay mineral.The results show that:First,comparing the average content of forest soil CEC in different climate zones,the order of average content is cold temperate zone>warm temperate zone>southern subtropical zone>central subtropical zone>mid temperate zone>tropical zone>northern subtropical zone.The soil CEC content in each climate zone varies greatly.The highest CEC content is Mohe in the cold temperate zone,with a content of160.37coml/kg,and the lowest CEC content is in the northern subtropical Taibai Mountain,with a content of 36.92coml/kg.Second,studying on the composition of forest soil particles in various climatic zones found,the clay soil content in the mid temperate forest soil is the highest in all climatic zone soils,while the clay soil content in the warm temperate forest soil is generally low.The clay content in the soils of Mohe,Maoer Mountain,Jiaohe,Taibai Mountain,Dujiangyan,Tiantong Mountain,Huanjiang,Huanglian Mountain and Xishuangbanna reached more than 30%.Third,the chemical composition of forest soil clay in each climate zone is mainly Si O₂,Al₂O₃,Fe₂O₃,the content of Si O₂ ranges from 340.2g/kg-555.8g/kg.The content of Al₂O₃ranges from 187.9g/kg-367g/kg.From north to south,the contents of Al₂O₃basically increase sequentially,and aluminum-rich phenomenon appears;Sa value and Saf value also basically show a decreasing trend,and the degree of soil weathering increases.Fourth,from the selective dissolution analysis of forest soil in each climate zone,we can know that the average value of DCB soluble component content in forest soil in each climate zone is:tropical zone(26.06)>southern subtropical zone(20.72)>central subtropical zone(17.95)>northern subtropical zone(11.05)>warm temperate zone(10.956)>mid temperate zone(9.605)>cold temperate zone(8.725).The highest content is Xishuangbanna in tropical zone,and the lowest content is in Genhe in the cold temperate zone.From north to south,the content of DCB soluble ingredients basically showed a gradual increase trend,indicating an increase in the degree of soil weathering.Fifth,the analysis of XRD patterns reveals that the clay minerals of the chernozem in Mohe and Genhe in the cold temperate zone are mainly of 2:1 type illite.The clay minerals in the black soil of Maoer Mountain and Jiaohe in the mid temperate zone are mainly 2:1 type illite and montmorillonite.The clay soil minerals in the warm temperate zone Wuling Mountain,Tianlong Mountain and Taishan Mountain are mainly illite and vermiculite.Taibai Mountains in the northern subtropical zone are mainly of 2:1 type illite.The clay minerals in the central subtropical zone soil are mainly 1:1 type kaolinite,followed by vermiculite.The kaolinite content of the red loam of Gutian Mountain,Tiantong Mountain and Longwan is higher than that of the yellow loam of Jinyun Mountain,Dujiangyan,Huanjiang and Huping Mountain.The clay minerals in the Ailao Mountain,Huanglian Mountain and Qingyuan red soil in the southern subtropical zone are mainly 1:1type kaolinite and vermiculite.The clay minerals in the brick red soil of tropical zone Xishuangbanna are mainly kaolinite.With the change of climate zone,temperature and precipitation increase,from north to south,the content of illite and montmorillonite shows a gradual decrease trend,while kaolinite shows a gradual increase trend.