| Desert biological soil crusts (BSCs) is a coherent compound of soil particle creatures,like bacteria, fungus, lichens and moss, and their metabolites, which is a kind of typicalground coverage in arid and semi-arid region and has important ecology function. It is aimportant part of landscape in arid and semi-arid areas, being considered as an importantreferent of soil surface stable conditions and indicator of ecosystem assessment. Study theeffects of BSCs on soil moisture and wind erosion would provide theoretical references forthe protection and exploitation of BSCs.This study, focusing on the typical BSCs in sourthern part of Mu Us sandland,discussed the influences of the BSCs on soil moisture, infiltration of rainfall, soil evaporationand temperature through field observation and indoor simulation experiment, and analyzedthe effects of BSCs on soil moisture and wind erosion using several indicators. The mainresults are as follows:1) In dry seasons, the average soil moisture of the soil profile (0-240cm) was15.79%lower in BSCs plots than in bare land; There was an increase of15.11%and9.74%in the plotcombined Artemisia desterorum Spreng with BSCs and the plot combined Amorphafruticosa L.with BSCs compared with the single BSCs.The plot of the Artemisiadesterorum Spreng with BSCs was3%higher than that of the Amorpha fruticosa L.withBSCs;The plot of the Artemisia desterorum Spreng with BSCs decreased by4.89%compared with the Artemisia desterorum Spreng plot;There was no significant differencebetween the plot which combine Artemisia desterorum Spreng with BSCs and theArtemisia desterorum Spreng plot. Compared with the bare land, the average soil moisturesof the soil profile (0-140cm) in Artemisia desterorum Spreng and Amorpha fruticosa L.plots decreased by4.80%and15.87%respectively. In rainy seasons, the BSCs andvegetation had similar effects on soil moisture but with little difference in the degrees.2) Compared with bare sand, the soil initial infiltration rate, steady infiltration rate,speed of infiltration peak, cumulative infiltration, saturated hydraulic conductivity in theplot with100%coverage of BSCs decrease by42.20%、65.85%、61.22%、60.51%and67.91%respectively.Meanwhile, although the soil daily evaporation of100%coverage ofBSCs was32.98%lower than that of bare sand in the water evaporation stage. But on the one hand,100%coverage of BSCs prolonged the stabilization stage, increased cumulativeevaporation (23.22%) and promoted a huge loss of water.On the other hand, the soil dailyevaporation of100%coverage of BSCs was15.61%higher than that of bare sand indeclining stage, and the soil moisture in5cm、10cm、15cm、20cm、25cm depths of100%coverage of BSCs were50.64%、12.84、43.42%、55.92%、56.08%lower than those of baresand respectively. This indicated that fostering BSCs on bare sand would generate obviousnegative effects on soil moisture in Maowusu sandland. It was necessary to take humaninterferences on BSCs.3) The soil temperature daily variation in the plots of BSCs was the same as that in theplots of bare sand in the same depth; from6:00to21:00(every3hours), the soil temperaturetrends along the vertical profiles was "\" type, Micro "(" type, obvious "(" type,"/" type,Micro ")" type,"\" type cyclical changes. The coverage of BSCs significantly reduced thesurface soil temperature (P <0.01). This indicated that from the angle of the heat, theexistence of BSCs could reduce soil evaporation.4)4)Wind erosion mainly occurs in winter and spring. During this period the soilamount of wind erosion accounts for at least71%of the total annual amount in Mu UsSandland.The appear of BSCs and vegetation significantly reduce wind erosion, the concreteperformance are as follows,Compared with the bare sand, the wind erosion of Artemisiadesterorum Spreng plot and Amorpha fruticosa L. plot decreased by77.2%and62.1%, thewind erosion of plot which combined Artemisia desterorum Spreng with BSCs and the plotwhich combined Amorpha fruticosa L.with BSCs decreased by96.9%and91.4%. The erosionreduction indexs of BSCs were0.63and0.53respectively, which were0.25,0.29lowerthan that of Artemisia desterorum Spreng plot and Amorpha fruticosa L. plot.This resultsindicated that when the BSCs combined with Artemisia desterorum Spreng or Amorphafruticosa L., the Artemisia desterorum Spreng or Amorpha fruticosa L. played an leading rolein protecting soil from wind erosion and BSCs played a minor role. The soil initial infiltration rate,the steady infiltration rate, the speed of infiltration peak, cumulative infiltration of40%coverage of BSCs were23.53%,30%,20.83%,24.51%higher than those of100%coverageof BSCs, which indicated that reducing the area of BSCs could significantly increase theinfiltration of soil water. The study shows in terms of not increasing wind erosion andimproving soil water condition, it is feasible to moderately interfere with the BSCs. |
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