| Biological soil crust is a common ground cover in arid and semi-arid areas,which has important ecological functions such as improving soil physical and chemical properties,enhancing soil stability and reducing soil erosion.Particle composition(texture),as the most basic physical attribute of soil,not only directly affects soil erosion resistance,but also affects soil erosion resistance by affecting the development,composition and distribution of biological crust.So far,few studies have compared the stability of soil biological soil crust composed of different particles,which hinders the accurate understanding of soil erosion resistance in arid and semi-arid areas.In this study,the biological soil crust of different soil composed of five types of particles in Loess Plateau region is studied.The stability of four types of biological soil crustal with different particle composition was studied by space-time intergenerational method.Based on this,the influence and mechanism of soil particle composition on the stability of biological soil crust were studied by measuring the physical and chemical properties of the soil and the mass,thickness,area loss rate and semi-loss oscillation times(50% of the maximum loss rate).The main conclusions are as follows:(1)The composition and development of biological crust in soil composed of different particles are different,and the total coverage of biological soil crust in sandy soil is significantly higher than that in loam soil.The distribution of biological soil crust on the soil with higher sand content was mainly moss crust,and the coverage reached 38%,which was higher than that of loam soil(the average coverage of moss crust was 14%).The distribution of biological crust in the area with higher clay content was mainly algae crust,with an average coverage of 39%.(2)The composition of soil particles has significant correlation with bulk density,polysaccharide content and stability of biological soil crust,and has no correlation with cohesion and organic matter.The composition of soil particles affects the bulk density and polysaccharide content of biological soil crust,and the bulk density of biological soil crust is negatively correlated with the ratio of soil particles(silt clay: sand).There was a significant positive correlation between the content of polysaccharides in biological soil crust layer and the content of coarse powder(0.01?0.05 mm)in soil particle composition,and a significant negative correlation with the content of coarse sand(0.25?1mm).(3)The type of biological soil crust significantly affects soil particle composition,bulk density,cohesion,organic matter content and stability,and has no significant effect on soil polysaccharidecontent.With the increase of moss coverage in biological soil crust,the content of coarse particles(0.05?1 mm)in biological soil crust decreased,the content of fine particles(0.002?0.01)increased,the bulk density of biological soil crust decreased,the cohesion increased,the content of organic matter increased,and the stability of the biological soil crust is increased.(4)Soil sand content,clay content and moss biomass in biological soil crust were important factors affecting the stability of biological soil crust.There was a significant negative correlation between biological soil crust stability and soil sand content and biological soil crust bulk density,and a significant positive correlation between soil silt content and moss biomass.The contribution of biological crust on soil made up of different particles to stability is different.The type of biological crust has a greater effect on stability in areas with high sand grain content,and the type of biological crust has a lesser effect on the area with higher viscosity and powder grain content.(5)Under the condition of artificial culture,the composition of soil particles had no significant effect on the coverage and thickness of biological crust,and has little effect on the stability of the cultured biological crust.After 27 days of artificial culture,the coverage reached the maximum,and the maximum coverage was about 80%.After that,the bryophyte plants died and the coverage of bryophyte was decreased.Both the thickness of biological crust are small,and the difference between soils with thickness less than 3 mm,different particle composition is not significant.Soil particle composition has little effect on the stability of cultured biological crust,the response of weight loss rate to the number of shocks is the same,and the difference of loss rate is not significant. |
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