Spatial Distribution Of Biological Soil Crusts And Their Soil Hydrological Processes In Sandy Land In The East Of Yellow River In Ningxia

Biological soil crusts are widely distributed in the region as a marker of mobile dune fixation in Sandy Land in the East of Yellow River in Ningxia,and their presence has altered the original pattern of soil hydrological processes in the system,thus creating a unique soil hydrological process that differs from the original desert ecosystem.In this paper,after characterizing the spatial distribution of biological soil crusts and their nutrients,we observe the response of different biological soil crusts and their subsoil to rainfall,and the impact of the soil infiltration,water condensation,and evaporation of soil water.To explore its important role in the water cycle and water balance of sandy ecosystems and its role in water redistribution,to provide a theoretical basis for desertification management and ecological restoration in drylands.The main research contents and conclusions of the paper are as follows.(1)The coefficients of variation(CV)of the three nutrient contents all reach the medium level:CVTN>CVSOC>CVTP.Moss crusts had a statistically more significant effect on SOC and TN,compared to their effect on TP.The spatial autocorrelation of SOC,TN and TP in the remaining soil layers is moderate.Spatial variation in TP is dominated by stochastic factors,while SOC and TN are dominated by structural factors.In crusts,SOC was high in the north-center and low in the south;TN was high in the south center and low in the northwest;TP was high in the east center and low in the north west.In the 0-5 cm and 5-10 cm layers,the distribution of SOC and TP was high in the center and low in the surroundings,and that of TN was high in the south and east and low in the surroundings.(2)Biological soil crusts had a significant effect on shallow soil properties,reducing the sand content of the subsoil by 2.0%-5.1%,increasing the fines content by 3.6%-5.8%,and increasing the organic matter content of the soil by 5-6 times;the total soil porosity and saturated water content decrease under algal and moss crusts,and the total soil porosity and saturated water content increased under herb-moss crusts.The total porosity and saturated water content of the soil under herbaceous-moss crusts increased.All three types of biological soil crusts showed a slight repulsion and the repulsion and repulsion intensity were as follows:AC>MC>H-MC;the presence of the crust layer reduced the depth of rainfall infiltration and makes the soil water shallow.(2)In conclusion,the existence of biological soil crusts with different levels of development changed the properties and infiltration characteristics of the soil.MC and AC led to decrease in water infiltration,while H-MC gave rise to the opposite.The average infiltration rate showed BS>H-MC>AC>MC,and the cumulative infiltration volume per hour showed H-MC>BS>AC>MC.Compared with BS,the initial infiltration rate of AC,MC and H-MC had a decrease of 14.3%,37.2%,11.8%separately,the decline in stable infiltration rate of AC and MC was 14.4%and 18.3%,and the stable infiltration rate of H-MC had a rise of 4.5%;The Kostiakov model performed better than the Horton and Philip models in the simulation of biocrusts infiltration processes.(3)Biological soil crusts significantly influenced condensation formation and soil water evaporation;compared to bare sand,total condensation from moss crusts and herb-moss crusts increased by 20.2%and 14.9%,respectively,while algae crusts decreased by 1.6%.Capturing condensation:MC>H-MC>BS>AC.Soil condensation(9.78mm)was the main source of condensation.The total daily evaporation from moss and herbaceous-moss crusts increased by 24.1%and 71.9%,respectively.The total daily evaporation of moss and herbaceous-moss crusts increased by 24.1%and 71.9%respectively;the total 15-day evaporation and the evaporation rate within a single day both showed H-MC>MC>BS>AC.