黄土丘陵区生物结皮对土壤入渗的影响

Impact of Biological Crust on Soil Infiltration in Hilly Areas of Loess Plateau

为了明确生物结皮对土壤入渗的影响,在黄土丘陵区沿降雨梯度从南到北大致按等间距分别在宜君、富县、延安、子长、子洲、榆林、东胜选取7个生物结皮发育较好的试验样地,并分别以无结皮样地作为对照,使用盘式入渗仪记录入渗过程并计算各入渗参数。结果表明,生物结皮可显著增大土壤表层有机质含量,但对土壤容重和土壤质地的影响不显著。生物结皮具有显著抑制土壤入渗的作用,从南到北土壤入渗性能呈现逐渐增加的趋势,但存在局部波动;从南到北7个生物结皮样地的饱和导水率、土壤初渗率及30min累积入渗量分别为0.18~0.39mm/min,1.31~2.72mm/min及15.18~43mm,从南到北7个对照样地的饱和导水率、土壤初渗率及30min累积入渗量分别为0.13~0.60mm/min,1.19~2.45mm/min及11.90~52.34mm。土壤初渗率和累积入渗量主要受土壤质地和初始含水量影响,土壤初始含水量对有无生物结皮生长土壤入渗过程的影响比较类似,而土壤质地对有生物结皮生长的样地入渗过程影响更显著;有无生物结皮条件下土壤饱和导水率均受土壤质地的影响,且土壤质地对无结皮样点的影响更显著。

In order to define the impact of biological soil crust on soil infiltration,the present study selected 7plots with well-developed biological soil crust and 7control plots with no crust in Yijun,Fuxian,Yan＇an,Zichang,Zizhou,Yulin and Dongsheng from south to north.These plots were distributed along aprecipitation gradient with a similar distance between them in hilly areas of Loess Plateau.The infiltration process was recorded by using disc permeameter,followed by the calculation of the infiltration parameters.The results indicated that biological soil crust could significantly increase the organic matter content of surface soil,but could not significantly affect soil bulk density and soil texture.Biological soil crust could significantly inhibit infiltration,and soil infiltration capacity showed a growing trend from south to north,but with some fluctuations.In the 7plots with well-developed biological soil crust,saturated hydraulic conductivity,initial infiltration rate and 30 min cumulative infiltration were 0.18~0.39mm/min,1.31~2.72mm/min and 15.18~43mm,respectively.In the 7control plots,saturated hydraulic conductivity,initial infiltration rate and 30 min cumulative infiltration were 0.13~0.60mm/min,1.19~2.45mm/min and 11.90~52.34 mm.Soil initial infiltration rate and cumulative infiltration were mainly affected by soil texture and soil initial moisture content.There were similar impacts of soil initial moisture content on soil infiltration for both biological soil crust plots and control plots,but effect of soil texture on soil infiltration was more significant in biological soil crust plots than in control plots.Soil saturated hydraulic conductivity of both biological soil crust plots and control plots were equally affected by soil texture,but the effect of soil texture in control plots was more significant than that biological soil crust plots.