Different Types Of Plantations In The Small Watershed Of Reshui River In Xichang Soil Consolidation Effect And Disaster Reduction Benefit Assessment

The vegetation ecosystem has the functions of regulating climate,increasing humidity,promoting precipitation,storing water and maintaining moisture,etc.Therefore,it can effectively prevent soil erosion and shallow landslides on the slope,reduce the degree of soil cracking on the slope,and increase the stability of the surface soil on the slope,etc.play an important role.In this paper,taking the small watershed of Reshui River in Xichang as the research object,the composition,distribution and soil characteristics of vegetation in the small watershed were analyzed,combined with the root tensile resistance and root-soil composite of typical trees(Pine Yunnan and Eucalyptus globulus)in the small watershed Body shear test is carried out to analyze the impact of vegetation ecosystem on improving soil structure,fixing soil,and increasing the stability of soil structure,so as to provide support for the research and development of ecological prevention and control technology for natural geological disasters in small watersheds in mountainous areas.The results show:(1)Vegetation type and biomass have regulatory effects on soil structure and hydraulic performance in small watersheds.The land use types in the small watershed of Shuihe River include forest land,grassland,cultivated land,construction land,roads and water areas;among them)the forest land area is the largest,and the vegetation distribution characteristics are mainly coniferous forests such as Yunnan pine and both broad-leaved forests.The soil properties of different types of vegetation in small watersheds were significantly different.Compared with barren grassland,soil bulk density decreased,porosity and water holding capacity increased under the action of Yunnan pine,Eucalyptus globulus and poplar,among which poplar had the most significant effect.Soil water holding capacity and porosity of different types of vegetation were positively correlated with vegetation biomass,while soil bulk density was negatively correlated with vegetation biomass.(2)By measuring the root resistance performance of P.yunnanensis and P.yunnanensis in red soil and yellow soil,under the condition of different root diameters,there is no significant difference in the increase of the tensile strength of P.yunnanensis and P.yunnanensis roots.There was no significant difference in tensile strength between Eucalyptus cyanus root and P.yunnanensis root,and the tensile strength decreased with the increase of root diameter,but the diameter-tensile strength fitting equation was different.The root system with a diameter of about 3.7 mm in the four groups was selected for root tensile sensitivity analysis.The results showed that the root systems of and Eucalyptus chinensis and P.yunnanensis were more stable in sensitivity to external force than those of Eucalyptus chinensis and P.yunnanensis in red soil.(3)The triaxial shearing experiment of plain soil and root-containing soil shows that plant roots can greatly improve the shear strength of soil,and the peak strength increases with the increase of root content.Under the condition of keeping the root diameter unchanged,the cohesion of the four groups of soils of yellow soil,yellow soil,Eucalyptus chinensis,red soil P.yunnanensis,and red soil eucalyptus increased with the increase of root content,and decreased slightly.The internal friction angle of the soil;under the same root content,with the increase of root content,the improvement of soil internal friction angle and cohesion of Eucalyptus root-containing soil is numerically better than that of the same group P.Yunnanensis.When the root content is the same,the peak shear resistance of the red soil and yellow Eucalyptus chinensis root-containing soils is slightly higher than that of the P.group soils with the same root content,but the difference is not significant.(4)Select 17 sub-items of 5 functions such as purifying the atmospheric environment,water conservation,soil conservation,tree accumulation of nutrients,carbon fixation and oxygen release,etc.to evaluate the quantity and value of ecological disaster reduction benefits in the small watershed of the Shuihe River.The results show that the annual ecological benefit created by tree plantations in the small watershed of Reshui River can reach 997 million yuan,which shows that tree planting plays an important role in protecting the local ecology and reducing disasters.The combination of engineering treatment and ecological measures not only reduces the harm to the life and property safety of local residents caused by natural disasters such as debris flows,but also coordinates the treatment engineering with the environment,and implements vegetation restoration and soil and water conservation projects in conjunction with local governments to reduce soil erosion.Bring good ecological and environmental benefits.