生物结皮生长发育对黄绵土抗侵蚀性能的影响

[目的] 黄土高原退耕还林(草)工程驱动的生物结皮发育可显著抑制土壤侵蚀,为探明土壤抗侵蚀性能随生物结皮生长发育的变化特征及其响应机制。[方法] 设置藻结皮、藓结皮和自然演替结皮3个处理,培育176天,系统研究生物结皮不同发育阶段及其类型差异对黄绵土抗侵蚀性能的影响。[结果] (1)生物结皮盖度、厚度、生物量、叶绿素和粗糙度随生长时间均显著增加,培育初期藓结皮较高,培育末期自然演替结皮反而最高。(2)随生物结皮发育,土壤黏结力呈幂函数增强,较初期增加39.8%~60.3%;质量损失率呈指数函数减小,较初期降低45.6%~57.3%;饱和导水率变化趋势较为复杂,但培育末期均最低(0.08~0.12 mm/min)。(3)土壤黏结力随生物结皮盖度、厚度、叶绿素、生物量和表面粗糙度的增加呈幂函数增长,质量损失率随生物结皮盖度、厚度、叶绿素、生物量和表面粗糙度的增加呈指数函数下降。(4)土壤抗侵蚀综合指数(C_ser)可表示为盖度(Cov)、厚度(T)和生物量(B)的幂函数(C_ser=0.279 Cov^0.194 T^0.188 B^0.119, R²=0.73, p＜0.05)。[结论] 黄土高原生物结皮发育可显著提高黄绵土抗侵蚀性能,藓结皮效果最强。

Effects of Biological Soil Crusts Development on Soil Erosion Resistance on Loessial Soil

[Objective] The extensive development of biological soil crusts driven by the project of "Grain for Green" on the Loess Plateau can significantly inhibit soil erosion, but the characteristics of soil erosion resistance and the response mechanism with the growth and development of biological soil crusts are still unclear. [Methods] Algal crusts, moss crusts, and natural succession crusts were cultivated for 176 days to systematically study the effects of different developmental stages and types of biological soil crusts on loessial soil erosion resistance. [Results] (1)The coverage, thickness, biomass, chlorophyll and roughness of the biological soil crusts increased significantly with growth time, and the moss crusts were higher at the beginning of cultivation and the natural succession crusts were highest at the end of cultivation.(2)With the development of biological soil crusts, the cohesion increased as a power function, which increased by 39.8%~60.3% compared with the initial period; the mass loss rate decreased exponentially, which decreased by 45.6%~57.3% compared with the initial period; and the saturated hydraulic conductivity(Ks)was more complex, but the Ks was lowest at the end of cultivation(0.08~0.12 mm/min).(3)Soil cohesion increased as a power function with the increase of coverage, thickness, chlorophyll, biomass and roughness, and the mass loss rate decreased exponentially with the increase of coverage, thickness, chlorophyll, biomass and roughness. (4) The comprehensive index of soil erosion resistance (C_ser) constructed based on soil properties can effectively show the effect of biological soil crusts development on soil erosion resistance. And the C_ser can be expressed as a power function of coverage (Cov), thickness (T) and biomass (B) (C_ser=0.279 Cov^0.194 T^0.188 B^0.119, R²=0.73, p＜0.05). [Conclusion] The development of biological soil crusts on the Loess Plateau can significantly improve soil erosion resistance, and the effect of moss crusts is the best.