西南喀斯特地区普遍发育的生物结皮,对土壤侵蚀有显著的抑制作用。以贵州喀斯特坡面不同退耕年限地块(0,3,5,8,11年)生物结皮为研究对象,对不同流量水平(0.2,0.3,0.4,0.5 L/s)和坡度(5°,12°,17°,23°)条件下生物结皮对土壤抗蚀性能的影响机制进行研究。结果表明:(1)生物结皮发育能够促进土壤颗粒胶结,增强土壤团聚体稳定性,改善土壤结构,提高土壤持水和透水能力。(2)生物结皮发育可增强土壤抗崩解和抗剪切能力,与去除结皮处理相比,结皮存在时的土壤抗崩解和抗剪切能力分别提高24.83%~46.62%和25.77%~37.73%。(3)发育年限内(3~11年)结皮层抗拉力变化范围为1.95~5.76 N,随着生物结皮发育年限增加,结皮层结构越趋稳定,其抵抗破坏的能力也越强。(4)生物结皮可明显提高土壤抗冲性能,且受流量和坡度的双重制约,流量和坡度都存在临界值,分别为0.4 L/s和17°,超过临界值后,其保护作用显著减弱。研究结果对于喀斯特地区准确估算土壤流失和生态恢复建设正确评价具有重要意义。
Biological soil crusts (biocrusts), which develop commonly in the southwestern karst regions, have a significant effect on reducing soil erosion. To explore the effect of biocrusts on soil anti-erodibility, biocrusts with different rehabilitation ages (0, 3, 5, 8, 11 a) were studied on a karst hillslope in Guizhou, and different levels of flow discharge (0.2, 0.3, 0.4, 0.5 L/s) and slope gradients (5°, 12°, 17°, 23°) were designed. The results showed that:(1) Biocrusts on karst hillslopes could promote soil particles cementation, strengthen soil aggregate stability, improve soil structure, and enhance soil water holding capacity and permeability. (2) The biocrusts greatly enhanced the anti-disintegration and anti-shear strength of soil. Compared with the treatment of removing biocrusts, the soil's anti-disintegration and anti-shear strength of the treatment of retained biocrusts increased by 24.83%~46.62% and 25.77%~37.73%, respectively. (3) The tensile strength of the biocrust layer ranged from 1.95 to 5.76 N during the rehabilitation ages (3~11 a). As the development age of biocrusts increased, the structure of the biocrust layer became more stable, and its ability to resist damage became stronger. (4) The biocrusts could also significantly improve the soil anti-scour capacity, which was regulated by flow discharge and slope gradient. The critical value for flow discharge and slope gradient was 0.4 L/s and 17°, respectively, beyond which the protective effect of biocrusts was significantly weakened. These results were of great significance for accurately estimating soil erosion and correctly evaluating ecological restoration construction in karst regions.
张思琪, 张科利, 马芊红.喀斯特坡面生物结皮发育对土壤抗蚀性能的影响[J].水土保持学报,2023,37(5):64~70复制