摘要:生物结皮在高寒地区广泛发育，是影响冻土环境的重要因素之一。为了解高寒冻土区生物结皮对浅层土壤水热过程的影响，以黄河源区玛多县季节冻土区生物结皮为研究对象，采用定位监测的方法，分析了统一地貌单元内两种不同类型的生物结皮对浅层（0-50 cm）土壤水热变化的影响。研究结果表明（1）生物结皮对冻土浅层土壤水热过程有显著的影响，且与土壤的冻结融化状态密切相关：在冻结状态下，生物结皮对土壤水分和温度均没有显著影响；而在融化期，与裸地相比，两种类型生物结皮均增加了不同土层土壤未冻水含量，同时降低了浅层土体温度。（2）生物结皮对冻土浅层土壤水热过程的影响还与生物结皮的类型密切相关：1）其中深色藻结皮增加了5-15 cm土层土壤含水量（1%-5.4%），而浅色藻结皮增加了30 cm土层土壤含水量（5%-12%），且深色藻结皮的降温效应（1.1-2.1℃）显著高于浅色藻结皮（0.8-1.3℃）。（3）生物结皮覆盖下冻土浅层土壤中未冻水含量与土壤温度呈复杂的耦合作用。根据土壤中未冻水含量与温度的变化关系可分为三个阶段：T < -4℃时，土壤处于完全冻结状态，深色藻结皮覆盖下，土壤未冻水含量保持在4.3%左右；当土壤温度-4 < T < 4℃时，土壤未冻水含量与土壤温度呈正相关关系，土壤温度影响土壤含水量，随着土壤温度升高土壤未冻水含量增加；土壤温度T > 4℃，土壤未冻水含水量与土壤温度呈负相关关系。此阶段水热相互耦合，随着土壤温度升高，土壤中未冻水含量的降低。同时土壤含水量影响土壤温度，随着土壤含水量的增加，土壤温度降低。研究结果揭示了高寒草甸退化过程中生物结皮对冻土浅层土壤水热过程的重要影响，这一研究结果将为后期冻土区生态修复提供理论依据。



Abstract:Biocrusts (biological soil crusts), as ubiquitous living covers on soil surface of the enclosure grassland in the frozen ground region of the Qinghai-Tibet Plateau, is one of the important factors which influenced the frozen soil environment. Based on the analysis of soil temperature and unfrozen water content of the shallow soil layer (0-50cm), the hydrothermal process of the shallow soil layer under the covering of two types of biocrusts in Maduo in the source area of the Yellow River (SAYR) were studied. Preliminary results showed that biocrusts have a significant impact on the unfrozen water content and soil temperature of the shallow soil layer. Compared with the bare soil, both types of biological crust increased the unfrozen water content of soil in different soil layers and lowered the temperature of shallow soil layer in the thawing period. While there is no significant effect on the soil unfrozen water content and temperature in the freezing period; In the thawing period, the biocrust decreased the soil unfrozen temperature in the shallow soil layer by 1.1-1.9℃, which was higher than that of the light biocrust by 0.8-1.1℃. Meanwhile, during the thawing period, the dark biocrust increased the soil water unfrozen content in the 5-15 cm soil layer by 1%-5.4%, while the light biocrust increased soil water content in 30 cm by 5%-12%, no significant effect on the 5 cm soil depth; Eventually, the hydrothermal coupling process was observed in the shallow layer of soil under biocrusts in the frozen ground region. The soil water-heat process could be divided into three stages according to the water and temperature changes: (1) when the soil temperature of soil crust was less than - 4℃, the soil unfrozen water content was maintained at 4.3%; (2) when the soil temperature increased from - 4℃ to 4℃, the soil water content would increase with the temperature increasing; (3) when the soil temperature was higher than 4℃, the soil unfrozen water content was more than 10%, the soil water content decreased with the soil temperature increasing. The results reveal the key effect of biocrusts on the hydrothermal process of frozen soil in the shallow soil layer and the study provides the theoretical basis for the ecological recovery in the frozen ground region.





PDF全文下载地址:

https://www.ecologica.cn/stxb/article/pdf/stxb201910152159