宁夏河东沙地生物土壤结皮对土壤性质及入渗过程的影响

Effects of biological soil crusts on soil properties and soil water infiltration process of sandy land in the east of Yellow River in Ningxia

为了揭示沙漠化治理过程中生物土壤结皮覆盖对土壤入渗过程的影响规律,以宁夏河东沙地人工沙漠治理区4种典型地表覆盖类型:裸沙(BS)、藻类结皮(AC)、藓类结皮(MC)、草本-藓类结皮(H-MC)为研究对象,基于野外双环入渗试验与室内模拟,分析了3种生物土壤结皮覆盖下土壤性质的变化与土壤入渗特征。结果表明:(1)与BS相比,3种结皮覆盖下表层土壤砂粒含量减少2.0%—5.1%,粉粒含量增加3.6%—5.8%,有机质含量增加了5—6倍,AC和MC覆盖下土壤总孔隙度与饱和含水量降低,而H-MC与之相反;(2)平均入渗速率表现为BS>H-MC>AC>MC,1h累计入渗量表现为H-MC>BS>AC>MC,与BS相比,AC、MC和H-MC的初渗速率依次减少了14.3%、37.2%、11.8%,AC、MC的稳渗速率分别降低了14.4%和18.3%,H-MC的稳渗速率增加了4.5%;(3)三种模型中,Kostiakov模型最适用于模拟生物土壤结皮覆盖下土壤水分入渗过程。综上,研究区内不同发育程度生物土壤结皮改变了下层土壤的性质以及土壤的入渗特征,MC与AC阻碍水分入渗,H-MC促进水分入渗。

In order to reveal the influence of biological soil crusts on soil infiltration in desertification combating areas,biological soil crusts including algae crusts(AC),mosses crusts(MC)and herb-mosses crusts(H-MC)in the artificial desert control area in the east of Yellow River in Ningxia were chosen as the main subjects.Based on double ring experiments and indoor simulation experiments,the properties of soil covered by the crusts and the characteristics of its infiltration were explored separately.The results showed that:(1)compared with bare sand(BS),the sand content on the surface covered individually by 3 other types of crusts decreased by 2.0%—5.1%,the silt content increased by 3.6%—5.8%,and the organic matter content increased by 5 to 6 times.Total porosity and saturated moisture of soil covered by AC and MC declined,while that of H-MC had the opposite trend;(2)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%;(3)The Kostiakov model performed better than the Horton and Philip models in the simulation of biocrusts infiltration processes.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.