黄土高原丘陵区生物结皮土壤的斥水性

Impact of biological soil crusts on soil water repellence in the hilly Loess Plateau region,China

采用滴水穿透时间法和酒精溶液入渗法,研究了黄土高原丘陵区浅色藻结皮、深色藻结皮、藻+少量藓结皮、藓+少量藻结皮、藓结皮5种不同发育阶段的原状生物结皮土壤的斥水性及其与土壤含水量的关系.结果表明:生物结皮增加了土壤的斥水性,其斥水强度和持久性均显著增加.生物结皮土壤的斥水性随生物结皮的演替逐渐降低,当生物结皮中藓类植物盖度在20%以上时,斥水持久性显著低于藻结皮.生物结皮土壤的斥水性与土壤含水量及优势种密切相关,藓类生物结皮土壤的斥水性随着含水量的降低逐渐增加,藻类生物结皮土壤的斥水性随含水量的变化呈双峰曲线.

By using water drop penetration time （WDPT） and molarity of ethanol droplet （MED） methods, the soil water repellence of undisturbed biological soil crusts （biocrusts） in five successional stages, from the hilly Loess Plateau region of China was tested. The five stages of biocrusts were light cyanobacterial crust, dark cyanobacterial crust, cyanobacterial with sparse moss crust, moss and tiny cyanobacteria patches crust and moss dominated crust. The results showed that 1 ） the soil water repellence was markedly increased both in the intensity and persistence since the formation of biocrusts. 2） The soil water repellence showed a decrease trend along with the successional stages of biocrusts. The soil water repellence of the biocrusts with the moss coverage above 20% was significantly lower than that of the cyanobacterial crusts. 3 ） The soil water repellence of the biocrusts was closely related to soil moisture and the dominant organism. The soil water repellence increased with the decrease of soil water content for the moss dominated biocrusts, while changed in a bimodal curve with the decrease of soil water content for the cyanobacterial biocrusts.