1.中国农业大学 土地科学与技术学院/农业农村部华北耕地保育重点实验室;2.中国科学院 水利部 水土保持研究所 黄土高原土壤侵蚀与旱地农业国家重点实验室;3.中国科学院 西北生态环境资源研究院
1.College of Land Science and Technology, China Agricultural University/Key Laboratory of Arable Land Conservation in North China, Ministry of Agriculture and Rural Affairs;2.Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau;3.Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences
The National Natural Science Foundation of China (No.42077010), the “Light of West China” Program of the Chinese Academy of Sciences (No.2019), and the 2115 Talent Development Program of China Agricultural University (No.1191-00109011).
为探明黄土高原生物结皮的纳尘与固土效应及其影响因素，以进一步明确其对土壤母质的风积作用，本研究以典型风沙土和黄绵土上发育的生物结皮为对象，通过野外采样、室内分析以及模拟纳尘试验，比较了不同发育阶段生物结皮（藻结皮、藻—藓混生结皮、藓结皮）的纳尘量和固土量，探究了不同风速、降尘粒径和降尘量下生物结皮纳尘量的变化规律，并分析了影响生物结皮纳尘量和固土量的关键因素。结果表明，相同条件下生物结皮的纳尘量为无结皮的1.1倍～4.8倍，且随生物结皮由藻到藓的正向演替而增加。风速为1～8 m·s-1时，生物结皮的平均减蚀量可达19.5～4892.7 t·km-2·a-1。同时，生物结皮的纳尘量随含水率升高而增加，且增幅与风速呈正相关；相对含水率由0增至80%后，风速5～8 m·s-1下生物结皮的纳尘量分别平均提升了4.9%、53.1%、59.6%和72.3%。此外，生物结皮的纳尘量还随地表粗糙度增加而显著升高。与纳尘量的变化规律相似，生物结皮的固土量也随结皮发育阶段的正向演替而增大，其中藓结皮的固土量为藻结皮的1.4倍。在同一发育阶段，风沙土上发育的生物结皮其固土量显著高于黄绵土上发育的生物结皮（F=30.74，P<0.003）。生物结皮的固土量与结皮层厚度呈极显著正相关关系，且随土壤含水率增加呈先升高后降低的趋势。综上，生物结皮具有显著的纳尘与固土效应，其对黄土高原土壤母质的风积过程具有重要促进作用。
【Objective】 Wind activity and aeolian dust transportation are key terrestrial processes in dryland ecosystems. Biocrusts are photoautotrophic communities that consist of cyanobacteria, actinomycetes, mosses, green algae, fungi, and other organisms. As an important living skin and pioneer communities developing on surface soil in drylands, biocrusts strongly influence most soil processes (hydrological, ecological, biological, and chemical processes) and have a variety of essential ecological functions. Although biocrusts are usually relatively thin (a few millimeters or centimeters at most), these organisms have unique micro-structures which could positively influence the formation of aeolian soil parent material. In order to further explore the aeolian sedimentary effects of biocrusts on soil parent material, we conducted this study to understand the effects of biocrusts on dustfall retention and soil fixation, as well as their influencing factors.【Method】 In the north of Chinese Loess Plateau, the biocrusts developed on aeolian and loessal soils were sampled, and the analyses and simulated experiments were carried out in the laboratory. The amount of dustfall retention and soil fixation of biocrusts at different developmental stages (cyano crust, mixed crust, and moss crust) were measured. The variations of dustfall retention amount under different wind speeds, dustfall grain sizes, and dustfall amount were explored. We also explored the key influencing factors.【Result】 The dustfall retention amount of biocrusts was 1.1~4.8 times higher than that without biocrusts, and it increased with the developmental stages of biocrusts from cyano crust to moss crust. On average, the erosion reduction of biocrusts was 19.5~4892.7 t·km-2·a-1 under 1~8 m·s-1 wind speeds. Moreover, the dustfall retention amount increased with increasing soil water content, and these increases were positively correlated with wind speed. It was found that the dustfall retention amount was increased by 4.9%, 53.1%, 59.6%, and 72.3%, respectively, under 5~8 m·s-1 wind speeds when relative water content increased from 0 to 80%. Additionally, the dustfall retention amount was also significantly and positively correlated with the surface roughness of biocrusts. Similarly, the soil fixation amount of biocrusts also increased along with their developmental stages from cyano crust to moss crust. The soil fixation amount of moss crust was 1.4 times higher than that of cyano crust. At the same developmental stage, the soil fixation amount of biocrusts on aeolian sandy soil was significantly (F=30.74, P<0.003) higher than that on loessal soil. Furthermore, the soil fixation amount was positively correlated with the thickness of biocrusts and negatively correlated with the surface roughness. It firstly increased and then decreased with increasing soil water content.【Conclusion】 These findings show that biocrusts can significantly retain dustfall and fix soil due to their root, mycelium, exudates, and pore structures, and these biocrust functions are of great significance for the aeolian sedimentary process of soil parent material, the pedogenic process of primitive soil, and the primary succession of dryland ecosystem in the Chinese Loess Plateau. Additionally, this study demonstrates the important effects of biocrusts on the formation of aeolian soil parent material, and their key influencing factors are surface roughness, developmental stages, and water content of biocrusts. Therefore, it is essential to pay attention to the biocrust effects on dust retention and soil fixation in arid and semiarid climate regions.
CAO Yousong, XIAO Bo, LI Shenglong, WANG Yanfeng, YU Xingxing. Effects of Biocrusts on Dustfall Retention and Soil Fixation and Their Influencing Factors in the Chinese Loess Plateau[J]. Acta Pedologica Sinica, DOI:10.11766/trxb202112150675,[In Press]