Research On Soil Anti-erodibility And Soil Anti-scouribility Of Typical Forests In Beichuan Area

Topography of Beichuan area is complicated, elevation difference of mountains are large, as well as river bed gradient, valleys and rivers are mixed together. After5·12Wenchuan earthquake, vegetation destroyed seriously, frequent natural calamities such as landslide, debris flow, collapse, combined with local farmers to irrational factors such as reclamation and grazing, enormous damage destroyed Beichuan’ limited soil and water resources. Taking the typical forest in Beichuan area:①Alnus cremastogyne②Cunninghamia lanceolata③Phyllostachys pubescens④20years old Cryptomeria fortune⑤10years old Cryptomeria fortune⑥5years old Cryptomeria fortune⑦Alnus cremastogyne And Cryptomeria fortune⑧Barren grassland as the research object, measured soil anti-erodibility indices, soil anti-scouribility indices and soil physical and chemical properties. Comprehensive system research was made to soil anti-erodibility and soil anti-scouribility of beichuan area. Main conclusions are as follows:(1)In the aspect of soil anti-erodibility:the soil anti-scouribility indices of different forests have significant difference. The soil anti-erodibility index of20years old Cryptomeria fortune was the largest,which reached66.3percent. The barren grassland was the smallest, only11.8percent. Therefore forests have obvious effect on strengthening the soil anti-erodibility. From the three Cryptomeria fortune forests, we can see that soil anti-erodibility will increase with the increase of forest age. In terms of the same forest, the soil anti-erodibility of the upper gradation is superior to the lower gradation, upper gradation’ soil anti-erodibility indices is1.04～1.61times than lower gradation. Soil anti-erodibility index (S) will reduce with the grain of immersion time(t), a significant cubic function relation between them. Soil anti-erodibility has a significant correlation with reunite degree, the condition of reunion, dispersion ratio, organic matter, alkali-hydrolyzale nitrogen, effective phosphorus, rapidly-available potassium. After using method of principal component analysis. we can drawn the conclusion that soil anti-erodibility of20years old Cryptomeria fortune(55.941)was the largest, followed by Alnus cremastogyne And Cryptomeria fortune (53.195),10years old Alnus cremastogyne (44.482), Cunninghamia lanceolata (41.358), Phyllostachys pubescens (39.387), Alnus cremastogyne (31.014),10years old Alnus cremastogyne (30.642), barren grassland (22.936) was the worst.(2) In the aspect of soil anti-scouribility:the soil anti-scouribility of different forests have significant difference. The soil anti-scouribility index of Phyllostachys pubescens was the biggest, which was28.144(L*min/g),barren grassland(3.613) was the smallest. In terms of the same forest, the soil anti-erodibility of the upper gradation is superior to the lower gradation, upper gradation’soil anti-scouribility indices is1.161～2.161times than lower gradation. Soil anti-scouribility index (S) will increase with the grain of scouring time(t), a extremely significant cubic function relation between them. A significant positive correlation between soil anti-scouribility indices and root length of<0.05mm, root length of<0.05-1mm, and root biomass. So, Phyllostachys pubescens with high content of fibril and radicula has better soil anti-scouribility. There was a significant correlation between soil anti-scouribility index and total soil porosity, bulk density, dispersion rate.