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草业学报 ›› 2025, Vol. 34 ›› Issue (12): 1-15.DOI: 10.11686/cyxb2025034

• 研究论文 •    

灌丛化对黄土高原草地土壤有机碳组分与稳定性的影响及其微生物调控机制

景煜都1,2,3(), 刘小伟4, 梁可4, 封俊豪4, 于强5, 郭梁5,6()   

  1. 1.中国科学院教育部水土保持与生态环境研究中心,陕西 杨凌 712100
    2.中国科学院水利部水土保持研究所,陕西 杨凌712100
    3.中国科学院大学,北京 100049
    4.西北农林科技大学草业与草原学院,陕西 杨凌 712100
    5.西北农林科技大学水土保持与荒漠化整治全国重点实验室,陕西 杨凌 712100
    6.宁夏云雾山国家级自然保护区管理局,宁夏 固原 756000
  • 收稿日期:2025-02-02 修回日期:2025-04-03 出版日期:2025-12-20 发布日期:2025-10-20
  • 通讯作者: 郭梁
  • 作者简介:E-mail: guoliang2014@nwafu.edu.cn
    景煜都(1998-),男,山西运城人,在读硕士。E-mail: jingyudu22@mails.ucas.ac.cn
  • 基金资助:
    国家自然科学基金(42377471);宁夏回族自治区自然科学基金(2024A AC05099)

Impacts of shrub encroachment on the fraction and stability of soil organic carbon of grassland on the Loess Plateau, and the underlying microbial mechanisms

Yu-du JING1,2,3(), Xiao-wei LIU4, Ke LIANG4, Jun-hao FENG4, Qiang YU5, Liang GUO5,6()   

  1. 1.The Research Center for Soil and Water Conservation and Ecological Environment,Chinese Academy of Sciences and Ministry of Education,Yangling 712100,China
    2.Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,Yangling 712100,China
    3.University of Chinese Academy of Sciences,Beijing 100049,China
    4.College of Grassland Agriculture,Northwest A&F University,Yangling 712100,China
    5.State Key Laboratory of Soil and Water Conservation and Desertification Control,Northwest A&F University,Yangling 712100,China
    6.Ningxia Yunwushan National Nature Reserve Administration,Guyuan 756000,China
  • Received:2025-02-02 Revised:2025-04-03 Online:2025-12-20 Published:2025-10-20
  • Contact: Liang GUO

摘要:

灌丛化显著影响全球草地生态系统的碳循环,但其对土壤有机碳组分及稳定性的影响,尤其是微生物在其中的调控机制,仍然缺乏深入研究。本研究以黄土高原半干旱草原为对象,分析了不同类型灌丛化对土壤理化与生物性质、有机碳组分与占比、微生物群落特性的影响,以及其中的微生物调控机制。结果表明,半灌木(白莲蒿)和灌木(矮脚锦鸡儿)扩张的生态影响差异不显著,但两种类型的灌丛化显著提高了土壤含水量(SWC)、土壤总有机碳(SOC)含量、可溶性有机碳(DOC)含量与全量养分,促进了碳循环相关酶活性上升与微生物残体碳积累,并显著提高了矿物结合态有机碳(MAOC)、颗粒态有机碳(POC)的绝对含量与MAOC的相对占比,显著降低了土壤pH与POC的相对占比。此外,灌丛化显著改变了土壤细菌与真菌群落组成,提高了土壤细菌的硝化作用、硫化物氧化与铁呼吸功能,同时增强了真菌的凋落物腐生与木本腐生营养型的丰度。土壤微生物残体碳及细菌的功能均与POC和MAOC的含量和占比显著相关。偏最小二乘路径分析进一步表明,与碳循环相关的胞外酶活性和微生物残体碳分别是调控土壤有机碳组分含量与其相对占比的直接微生物因素,而微生物群落组成通过间接途径影响这些过程。总之,灌丛化不仅显著增加了草地土壤碳库的总量及各有机碳组分的含量,还提高了土壤碳库的稳定性,而土壤微生物分泌的胞外酶与微生物残体碳在该过程中起到重要调控作用。本研究为深入理解灌丛化对草地土壤碳组分的微生物调控机制,并为预测黄土高原灌丛化草地土壤碳库未来变化提供了理论支持。

关键词: 黄土高原半干旱草地, 灌丛化, 有机碳组分, 土壤微生物

Abstract:

Shrub encroachment is significantly affecting carbon cycling in grassland ecosystems worldwide, yet its impact on the components and stability of grassland soil organic carbon, and particularly the underlying microbial regulatory mechanisms, remains insufficiently studied. In this study, we focused on the semi-arid grassland of the central Loess Plateau, and analyzed the effects of shrub encroachment on various soil physicochemical and biological properties, organic carbon components and their proportions, microbial community structure, functions, and trophic types, as well as the underlying microbial regulatory mechanisms. The results show that shrub encroachment significantly increased the total organic carbon, dissolved organic carbon, mineral-associated organic carbon (MAOC), and particulate organic carbon (POC) contents in soil, and the relative proportion of MAOC, but significantly decreased the relative proportion of POC. Furthermore, shrub encroachment significantly altered the bacterial and fungal community composition by affecting soil physicochemical properties, with different impacts on the relative abundance of amplicon sequence variants of different phyla. Shrub encroachment enhanced soil bacterial nitrification, sulfur oxidation, and iron respiration functions, as well as the abundance of fungal saprotrophic and woody saprotrophic type functions, but reduced the abundance of bacterial methylotrophy and aromatic compound degradation functions. The soil microbial residue carbon and bacterial functions were significantly correlated with the contents and proportions of POC and MAOC. A partial least squares path analysis showed that extracellular enzyme activity and microbial residue carbon, related to carbon cycling, were the microbial factors directly regulating the contents and relative proportions of soil organic carbon components, whereas microbial community composition influenced these processes indirectly. These results indicate that shrub encroachment not only increases the total amount of soil carbon and the contents of soil organic carbon components in grassland soils, but also significantly enhances the stability of the soil carbon pool, with extracellular enzymes secreted by soil microbes and microbial residue carbon playing crucial regulatory roles. The findings of this study provide new information about the mechanisms by which microbes regulate organic carbon components in grassland soils under shrub encroachment. These results provide theoretical support for predicting future changes in the soil carbon pool of shrub-encroached grassland on the Loess Plateau.

Key words: semi-arid grasslands on the Loess Plateau, shrub encroachment, organic carbon fractions, soil microorganisms