三峡库区生物结皮对土壤分离过程的影响及其机制
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S157.1;S154.1

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国家自然科学基金项目(41877082)和中央级公益性科研院所基本科研业务费专项资金项目(CKSF2021487/TB)资助。


Effects and Mechanism of Biocrusts on Soil Detachment Process by Overland Flow in the Three Gorges Reservoir Area
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    摘要:

    为探明三峡库区生物结皮对土壤分离过程的影响及机制,以湖北省秭归县王家桥小流域为研究区域,选取以苔藓为优势种的生物结皮样地,以无结皮覆盖的裸地为对照,设计5个结皮盖度水平(1% ~ 20%、20% ~ 40%、40% ~ 60%、60% ~ 80% 和80% ~ 100%),采集原状土样,进行不同侵蚀动力条件下(水流剪切力4.89 ~ 17.99 Pa)的冲刷试验,建立生物结皮盖度与土壤分离能力、细沟可蚀性和临界剪切力间的定量关系,明确影响土壤分离过程的主要因素并阐明其作用过程。结果表明,生物结皮盖度显著影响土壤分离,裸地的土壤分离能力(0.160 kg/(m2·s))为生物结皮土壤(0.008 ~ 0.081 kg/(m2·s))的1.9倍 ~ 21.0倍,裸地的细沟可蚀性(0.018 7 s/m)为生物结皮土壤(0.009 5 ~ 0.000 9 s/m)的2.0倍 ~ 20.0倍;相对土壤分离速率和细沟可蚀性均随结皮盖度的增加呈指数衰减;通径分析显示土壤分离能力主要受结皮盖度、土壤黏结力和沙粒含量的影响,细沟可蚀性主要受结皮盖度和土壤容重的影响;非线性回归表明,土壤分离能力可用水流剪切力、黏结力和结皮盖度的幂函数进行模拟(NSE=0.947)。综上,三峡库区生物结皮的发育有效增强了土壤侵蚀阻力,其抑制土壤分离主要通过地表覆盖的直接保护作用和土壤属性的间接改变作用。

    Abstract:

    The study quantified the effects of moss-dominated biocrusts on soil detachment capacity (Dc) and soil erosion resistance to flowing water in the Three Gorges Reservoir Area. Potential factors driving soil detachment variation and their influencing mechanism were analyzed and elucidated. Five levels of coverage treatments (1% ~ 20%, 20% ~ 40%, 40% ~ 60%, 60% ~ 80% and 80% ~ 100%) were designed and a nearby bare land was taken as control in a moss-dominated site. Undisturbed soil samples were taken and subjected to flow scouring in a hydraulic flume under six shear stresses ranging from 4.89 to 17.99 Pa. The results indicated that mean Dc of moss-crusted soil varied from 0.008 to 0.081 kg/(m2·s), which was 1.9 to 21.0 times lower than that of bare land (0.160 kg/(m2·s)). Rill erodibility (Kr) of moss-crusted soil ranged from 0.009 5 to 0.000 9 s/m, which was 2 to 20 times lower than that of bare land (0.018 7 s/m). Both relative soil detachment rate and Kr showed an exponential decay with increasing biocrust coverage, whereas the critical shear stress (τc) for different biocrust coverage levels did not differ significantly. Biocrust coverage, soil cohesion, and sand content were key factors affecting Dc, while biocrust coverage and soil bulk density were key factors affecting Kr. A power function of flow shear stress, soil cohesion, and biocrust coverage fitted well to estimate Dc (NSE=0.947). Our findings implied that biocrusts prevented soil detachment directly by their physical cover and indirectly by soil properties modification. Biocrusts could be rehabilitated as a promising soil conservation measure during ecological recovery to enhance soil erosion resistance in the Three Gorges Reservoir Area.

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张冠华,易亮,丁文峰,王一然,蒲坚,孙宝洋.三峡库区生物结皮对土壤分离过程的影响及其机制[J].土壤,2021,53(3):610-619. Zhang Guanhua, YI Liang, Ding Wenfeng, WANG Yiran, PU Jian, SUN Baoyang. Effects and Mechanism of Biocrusts on Soil Detachment Process by Overland Flow in the Three Gorges Reservoir Area[J]. Soils,2021,53(3):610-619

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  • 收稿日期:2020-10-20
  • 最后修改日期:2020-12-22
  • 录用日期:2020-12-31
  • 在线发布日期: 2021-06-18
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