黄土丘陵沟壑区退耕地植被恢复中生物土壤结皮特征

Characteristics of Biological Soil Crusts During Vegetation Restoration of Abandoned Lands in Hill and Gully Region of Loess Plateau

以黄土丘陵沟壑区安塞县墩滩山的退耕地为研究对象，分析了退耕地植被自然恢复过程中生物土壤结皮的特点及其对土壤水分、土壤有机质和土壤侵蚀的影响。结果表明：（1）生物土壤结皮的盖度随着退耕年限的增长不断增大，结皮的厚度也渐渐增加，且稳定在0．1～0．3cm之间；（2）有结皮样地0—40cm土层的土壤含水量一般比对照样地的土壤含水量要低，有结皮样地和对照土壤含水量都随土层深度逐渐升高，但升高幅度逐渐变小；（3）有生物结皮的样地土壤表层0—10cm有机质含量比对照样地有机质含量大；10—20cm土层有生物结皮的样地比对照样地有机质含量也高，但是差异不如0—10cm土层明显；（4）随着退耕年限的增长，土壤侵蚀量逐渐减少，与退耕初期相比，退耕10a以上样地土壤侵蚀量可减少30％-80％。说明在退耕地植被恢复的过程中，生物结皮改善了土壤表层性质，增强了土壤抗侵蚀能力。

The properties of biological soil crusts and their effects on soil water, organic matter and soil erosion on the lands abandoned during vegetation restoration in Duntan Hills, Ansai County, Shaanxi Province, which is located in the hill and gully region of the Loess Plateau, were analyzed. Results showed that： （1） after the abandonment, the coverage and thickness of biological soil crusts increased gradually with the increase of time, and the thickness varied from 0.1 to 0.3 cm; （2） the soil water content in the sample plots without biological soil crusts was higher than that in the sample plots with biological soil crusts, and the soil water content increased with the increase in soil depth within 0-40 cm of the soil surface; （3） the organic matter content within 0-10 cm of the soil surfaces in the sample plots with biological soil crusts was higher than that of the sample plots without biological soil crusts, and the relation was the same in the soil layers of 10-20 cm, but the variation was not distinct as within 0-10 cm of the soil surface; （4） after the abandonment, the amount of soil erosion decreased gradually with the increase of time, and compared with the early abandoned plots, the amount of soil erosion in the sample plots in more than 10 years decreased by 30 % -80 %. The results illuminate that biological soil crusts could improve the characteristics of soil surface layers on the abandoned lands during vegetation restoration, and enhance the soil ability to resist erosion.