Hydrological And Physical Properties Of Shell Sand And Fractal Characteristics Of Shell Sand Particles Of Typical Shrub-grass Community In The Shell Dyke Of The Yellow River Delta

In order to reveal the fractal characteristics of shell sand particles and the water storage capacity of shell sand in the typical shrub-grass community of the Yellow River Delta shell embankment,Three species of vegetation such as Ziziphus jujuba var.spinosa-Artemisia mongolica?ZA?,Periploca sepium Bunge-Messerschmidia sibirica?PM?and Artemisia mongolica-Phragmites australis?AP?herb community were taken as the research objects,and the different shrub-grass planting types of soil particle size distribution,single weight and multifractal characteristics were measured by laser diffraction analysis technique.and the bare land?CK?in the same section was used as a control.The laser diffraction analysis technique was used to measure the particle size distribution,single weight and multifractal characteristics of different shrub communities,and the water storage performance indexes were measured.The results show:?1?The volume fraction of soil particles>100?m in the different shrub-grass community is higher,and the shell sand has non-uniform distribution characteristics,which has obvious heterogeneity.The difference of monofractal between different soil layers in different shrub-grass community was significant?P<0.05?,and the monofractal was between1.997 and 2.585?mean value was 2.252?,which was significantly higher than that of bare land?1.212-1.982?.On the 0-30 cm soil layer,the monofractal of shell sand particles is ZA>PM>AP>CK,respectively higher 62.02%,39.29%,38.81%than bare land.The shrub-grass community can change the soil texture from coarse to fine.The transformation performance of shrub-grass community is better than that of herb community.The ZA has a fine texture on the soil layer of 0-30 cm.D₀,D₁,D₂,D₁/D₀ and D₀-D₁ were significantly different between the shell sand bare soil and the different soil layers of different shrub-grass community?P<0.05?.Except for the 0-10 cm and 20-30 cm soil layers in the bare land,the clay content is 0 and there is no multi-fractal feature.The mean value of D₀ in different soil layers of 0-30 cm is ZA>PM>AP>CK;different shrub-grass community have different D₁performances in different soil layers,which on the soil layer of 10-20 cm is ZA>PM>AP>CK,which compared with bare land,the three different shrub-grass community increased by14.93%,14.80%,12.42%.The monofractal of shell sand particles and the volume fraction of clay particles were significantly positively correlated with different shrub community types?P<0.01?,which was significantly negatively correlated with the volume fraction of sand grains?P<0.01?.The multifractal parameters of shell sand are related to the depth of the soil layer.The multi-fractal parameter D₀ on the soil layer of 0-20 cm increased with the increase of shell sand clay and powder content,and decreased with the increase of sand content.The relationship between D₀and particle content in the 20-30 cm soil layer is reversed.?2?The bulk density and porosity characteristics of shell sand under different shrub-grass community were significantly different?P<0.05?.The bulk density of shell sand under different shrub-grass community was lower than that in bare land,and the shell sand in the0-30 cm soil layer,AP,ZA and PM.The mean values were 18.84%,15.12%,and 13.49%lower than bare land.Respectively,the change of total porosity and bulk density of shell sand is opposite.The mean value is the AP>PM>ZA>CK,respectively higher 31.97%,19.50%,15.67%than bare land.The mean capillary porosity of ZA was higher than AP and PM.The non-capillary porosity of the AP has the largest average value and the ability to conserve water sources.The shell sand water-storage capacity in different shrub-grass community was significantly different?P<0.05?.The mean value of saturated water storage and precipitation of shell sand was AP>PM>ZA>CK,the water storage capacity of shell sand was respectively higher 32.58%,20.05%,and 16.21%than CK,and the precipitation of shell sand was higher32.61%,20.04%,and 16.17%than CK,respectively.The average volcanic volume of shell sand was AP>CK>ZA>PM.Under the same water suction,the water content of the shell sand of the ZA was significantly higher than that of PM and AP,while the water content of AP and CK.The difference was not significant.?3?The monofractal of shell sand is inconsistent with the density of shell sand and porosity.The most reflective is non-capillary porosity,followed by total porosity and bulk density.The monofractal of shell sand reflects the degree of water storage index.The highest degree of reflection is saturated water storage,the lowest of reflection is effective storage.The monofractal of shell sand in only on the soil layer of 10-20 cm increases with the increase of effective storage.The multifractal parameters of shell sand are different from the bulk density,porosity and water storage performance in different soil layers.The correlation between multi-fractal parameters and bulk density,porosity and water storage performance in 0-10 cm and 20-30 cm soil layers is not Significant?P>0.05?.The multifractal parameters D₁,D₂ and D₁/D₀ at 10-20 cm were significantly positively correlated with bulk density,porosity and water storage performance?P<0.05?.The water storage performance index of shell sand indirectly affects monofractal and multifractal,and the particle composition?clay,silt,sand content?directly affects the fractal dimension of shell sand.In the ridges of the shells of the Yellow River Delta,the ZA has the best water storage capacity for the shell sand,followed by the PM and AP.The worst,but significantly higher than the bare land,the water storage regulation ability of the shrub-grass community is reflected in the 10-20 cm soil layer,and the water storage regulation ability of the herb community is reflected in the 0-10 cm soil layer.