Zhao Yunge, Xu Mingxiang, Wang Quanjiu, Shao Ming'an
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences, Yangling 712100, China.
Ying Yong Sheng Tai Xue Bao. 2006 Aug;17(8):1429-34.
Soil bio-crust (SBC) plays an important role in degraded ecosystem restoration. The field investigation and laboratory analysis of SBC on different year rehabilitated grasslands at the north slope of hilly Loess Plateau showed that after cropland shifted to rehabilitated grassland, rainfall- induced structural crust appeared firstly, and then, with the increasing year of rehabilitation, crust- forming microorganism gradually settled in, and SBC developed. The depth of SBC increased in inverse "S" shape with increasing year of rehabilitation. 10 years after rehabilitation, the increase of SBC depth slowed down, and soil bulk density decreased from 1.4 g x cm(-3) to 1.1 g x cm(-3). SBC formation improved soil cohesion significantly, and the latter was increased in inverse "S" shape with increasing year of rehabilitation. The organic matter and total nitrogen contents in SBC were obviously higher than those in cropland, and increased gradually with increasing year of rehabilitation but tended to be stable after 10 years of rehabilitation. The available N, P and K contents in SBC were also increased, but no significant difference of total phosphorus was found between SBC and cropland soil. The formation of SBC in test region could be classified into 3 stages, i. e., the first stage named the beginning of the formation, which was from 1 to 4 years of grassland rehabilitation, the second stage named the rapid development period, which was from 5 to 10 years of the rehabilitation, and the third stage named stable period after 10 years of rehabilitation.
土壤生物结皮（SBC）在退化生态系统恢复中发挥着重要作用。对黄土高原丘陵北坡不同年份恢复草地的土壤生物结皮进行的野外调查和实验室分析表明，农田转变为恢复草地后，首先出现降雨诱导的结构结皮，然后随着恢复年份的增加，结皮形成微生物逐渐定居，土壤生物结皮得以发育。土壤生物结皮的深度随着恢复年份的增加呈反“S”形增加。恢复10年后，土壤生物结皮深度增加减缓，土壤容重从1.4 g·cm-3降至1.1 g·cm-3。土壤生物结皮的形成显著提高了土壤凝聚力，且土壤凝聚力随着恢复年份的增加呈反“S”形增加。土壤生物结皮中的有机质和全氮含量明显高于农田，且随着恢复年份的增加逐渐增加，但恢复10年后趋于稳定。土壤生物结皮中的有效氮、磷、钾含量也有所增加，但土壤生物结皮与农田土壤之间的全磷含量无显著差异。试验区土壤生物结皮的形成可分为3个阶段，即第一阶段为形成初期，是草地恢复1至4年；第二阶段为快速发展期，是恢复5至10年；第三阶段为恢复10年后的稳定期。
