黄土丘陵区不同盖度生物结皮土壤抗冲性研究

Soil Anti-Scourability of Biological Soil Crust with Different Coverage in Loess Hilly Region

按藓类植物所占结皮面积比例为盖度划分标准,采用变坡度水槽研究了不同盖度生物结皮对土壤抗冲性及黏结力、有机质、容重等理化属性的影响,探索了生物结皮理化属性与抗冲性之间的关系。结果表明:结皮容重随结皮盖度的增加呈不断减小的变化趋势4,盖度(苔藓盖度>80%)平均结皮容重比1盖度(苔藓盖度<20%)减小了16%;土壤黏结力、有机质、>5 mm水稳性团聚体百分比均随着结皮盖度的增加而增大。生物结皮通过本身分泌的有机凝胶体和多聚糖等胶结物质及菌丝之间的缠绕、包裹等作用,不但改善了土壤本身的理化属性,而且增强了松散土粒与土粒之间的黏结作用;结皮土壤抗冲刷时间随着结皮盖度的增加而延长,土壤侵蚀率随着结皮盖度的增加而减少,证实了结皮的形成和发育减少或避免了土壤侵蚀的发生与发展;生物结皮提高土壤抗冲性的作用主要表现在生物结皮提高了土壤黏结力与团聚体含量上。

The paper studied the influence of biological soil crust with different coverage to the physicochemical properties of soil anti-scourability,cohesion,organic matter and bulk density,and explored the relationship between the physicochemical properties of biological soil crust and anti-scourability by using variable slope flume,taking the crust proportion of mosses as the standard of coverage division.The outcomes show that: a) bulk density decreases gradually along with the increase of crust coverage and bulk density of crust coverage 4 is 16% less than that of crust coverage 1 and;b) the percentage of soil cohesion,organic matter and >5 mm water-stable aggregates increases with the increase of crust coverage.The organic gel and polysaccharides secreted by biological soil crust and the functions of winding and encapsulating interactions between mycelium have not only improved soil physicochemical properties but also enhanced the cohesive effects among soil particles.The anti-scourability time prolongs and soil erosion ratio decreases along with the increase of crust coverage,which has shown that the formation and development of soil crust have avoided the happening and development of soil erosion.The function of increased anti-scourability of biological soil crust mainly shows that the crust has increased the soil cohesion and contents of aggregates.