Sem-derived microstructure of cyanobacterial and moss biocrusts and their connections to mechanical stability of two contrasting dryland soils

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena Pub Date : 2024-11-15 DOI:10.1016/j.catena.2024.108537

Xingxing Yu , Bo Xiao , Yousong Cao , Giora J. Kidron

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Abstract

As an important biological component of the soil surface in drylands, biocrusts play an indispensable role in maintaining soil ecosystem multifunctionality. However, the microstructure of these biocrusts remains unclear. For this end, both cyanobacterial and moss crusts inhabiting sandy and loessial soils were collected on the Chinese Loess Plateau, and their profiles were thoroughly studied using scanning electron microscope (SEM). A full SEM image of each biocrust sample were quantitatively analyzed and their mechanical stability was measured. The SEM images showed that moss crusts had a more complex soil structure compared to cyano crusts. Furthermore, the filament density, ratio indices of soil particles to filaments (N_P/L_F and L_F/A_P), and the pore area ratio (PAR) of the moss crusts were higher than that of the cyano crusts on both soils. The penetration resistance (PR) and shear force of the moss crusts were higher than those of the cyano crusts on both soils, but the same type of biocrusts was less stable on the sandy soil than that on loessial soil. In addition, our results showed that the microstructure of biocrusts showed an obvious correlation with their PR, with an apparent threshold value for the effect of soil particles to filaments ratio indices of biocrusts on their mechanical stability. On the sandy soil, the PR of the biocrusts reached the maximum when N_P/L_F was 10.0–13.0 mm⁻¹, and L_F/A_P was 12.0–14.0 mm m⁻² (cyano crusts) and 21.0–29.0 mm m⁻² (moss crusts). While on the loessial soil, the PR of the biocrusts reached its maximum when N_P/L_F and L_F/A_P were 37.0–40.0 mm⁻¹ and 11.0–12.5 mm m⁻², respectively. Our study elucidated the microstructural characteristics of the biocrust profiles on the different soils and their thresholds affecting mechanical stability, which may help in the site-specific application of biocrusts in soil remediation and ecological restoration.

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蓝藻和苔藓生物簇的半衍生微结构及其与两种截然不同的旱地土壤力学稳定性的联系

作为干旱地区土壤表面的重要生物组成部分，生物簇在维持土壤生态系统多功能性方面发挥着不可或缺的作用。然而，这些生物结壳的微观结构仍不清楚。为此，研究人员在中国黄土高原采集了栖息于沙土和黄土中的蓝藻和苔藓结壳，并利用扫描电子显微镜（SEM）对其剖面进行了深入研究。对每个生物簇样本的完整扫描电子显微镜图像进行了定量分析，并测量了它们的机械稳定性。扫描电子显微镜图像显示，苔藓结壳与藻类结壳相比，具有更复杂的土壤结构。此外，苔藓结壳的丝状物密度、土壤颗粒与丝状物的比率指数（NP/LF 和 LF/AP）以及孔隙面积比（PAR）均高于两种土壤上的藻类结壳。苔藓结壳的穿透阻力（PR）和剪切力在两种土壤上都高于藻类结壳，但同一类型的生物结壳在沙质土壤上的稳定性低于在黄土上的稳定性。此外，我们的研究结果表明，生物结壳的微观结构与其PR有明显的相关性，生物结壳的土壤颗粒与菌丝比指数对其力学稳定性的影响有一个明显的临界值。在砂质土壤上，当 NP/LF 为 10.0-13.0 mm-1 ，LF/AP 为 12.0-14.0 mm m-2 （藻类结壳）和 21.0-29.0 mm m-2 （苔藓结壳）时，生物结壳的 PR 达到最大值。而在黄土上，当 NP/LF 和 LF/AP 分别为 37.0-40.0 mm-1 和 11.0-12.5 mm m-2 时，生物结壳的 PR 达到最大值。我们的研究阐明了不同土壤上生物簇剖面的微观结构特征及其影响机械稳定性的阈值，这可能有助于生物簇在土壤修复和生态恢复中的具体应用。

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来源期刊

Catena 环境科学-地球科学综合

CiteScore

10.50

自引率

9.70%

发文量

816

审稿时长

54 days

期刊介绍： Catena publishes papers describing original field and laboratory investigations and reviews on geoecology and landscape evolution with emphasis on interdisciplinary aspects of soil science, hydrology and geomorphology. It aims to disseminate new knowledge and foster better understanding of the physical environment, of evolutionary sequences that have resulted in past and current landscapes, and of the natural processes that are likely to determine the fate of our terrestrial environment. Papers within any one of the above topics are welcome provided they are of sufficiently wide interest and relevance.