Wu Mengyao, Chen Lin, Chen Shenggang, Chen Yinglong, Ma Jinpeng, Zhang Yaqi, Pang Danbo, Li Xuebin
College of Forestry and Prataculture, Ningxia University, Yinchuan, 750021, China; Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Ningxia University, Yinchuan, 750021, China; Ministry of Education Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China, Ningxia University, Yinchuan, 750021, China.
Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Ningxia University, Yinchuan, 750021, China; Ministry of Education Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China, Ningxia University, Yinchuan, 750021, China.
J Environ Manage. 2025 Jan;373:123675. doi: 10.1016/j.jenvman.2024.123675. Epub 2024 Dec 13.
Microorganisms play dual roles in soil organic carbon (SOC) decomposition and accumulation. Despite advancing insights into their involvement in the carbon cycle, understanding the impact of microbial community structure and physiological traits on SOC stabilization in arid and semi-arid grasslands remains elusive. Here, we analyzed arid and semi-arid grasslands SOC stability by comparing the ratio of mineral-associated organic carbon (MAOC) to particulate organic carbon (POC) across a grassland transect in north-south Ningxia, encompassing various grassland types and a broad climatic gradient (ΔMAP = 450 mm). By combining phospholipid fatty acid (PLFA) analysis, enzyme activity vector models and stoichiometric theory, the influence of soil microbial community compositions, metabolic constraints, and carbon use efficiency (CUE) on SOC stability were explored. Results showed that SOC stability was the lowest in desert areas and decreased with increasing mean annual precipitation (MAP) in other grasslands. Microbial physiological traits, including microbial carbon (C) limitation, nitrogen (N) limitation, CUE, and lignocellulose index (LCI) varied among grasslands, with significantly higher LCI and CUE and lower C and N limitation in steppe desert. The variation of microbial physiological characteristics accounted for 53.28% of the variation in SOC stability. Distinct microbial metabolic limitations were evident in these grasslands, with N and C limitation prevailing and exerting strong negative impacts on CUE. Decreased fungal/bacterial (F/B) ratios also reduced microbial CUE and indirectly diminished SOC stability. In addition, clay content emerges as a major factor influencing the stabilization of SOC across environmental gradients. Collectively, our work suggests that mitigating microbial C and N limitation and enhancing microbial CUE under the influence of MAP and clay content are the key mechanisms governing SOC stabilization in regional grasslands. These findings bear significant implications for understanding microbial-mediated carbon cycling processes in arid and semi-arid grasslands.
微生物在土壤有机碳（SOC）分解和积累过程中发挥着双重作用。尽管对其在碳循环中的作用有了更深入的认识，但了解微生物群落结构和生理特性对干旱和半干旱草原SOC稳定的影响仍然不够清晰。在此，我们通过比较宁夏南北草原样带中与矿物结合的有机碳（MAOC）与颗粒有机碳（POC）的比例，分析了干旱和半干旱草原的SOC稳定性，该样带涵盖了各种草原类型和广泛的气候梯度（ΔMAP = 450毫米）。通过结合磷脂脂肪酸（PLFA）分析、酶活性向量模型和化学计量理论，探讨了土壤微生物群落组成、代谢限制和碳利用效率（CUE）对SOC稳定性的影响。结果表明，沙漠地区的SOC稳定性最低，其他草原地区的SOC稳定性随年平均降水量（MAP）增加而降低。微生物生理特性，包括微生物碳（C）限制、氮（N）限制、CUE和木质纤维素指数（LCI）在不同草原之间存在差异，草原荒漠中的LCI和CUE显著更高，C和N限制更低。微生物生理特征的变化占SOC稳定性变化的53.28%。这些草原中明显存在不同的微生物代谢限制，N和C限制普遍存在，并对CUE产生强烈负面影响。真菌/细菌（F/B）比率的降低也会降低微生物CUE，并间接降低SOC稳定性。此外，粘粒含量是影响环境梯度下SOC稳定的主要因素。总体而言，我们的研究表明，在MAP和粘粒含量的影响下，减轻微生物C和N限制并提高微生物CUE是区域草原SOC稳定的关键机制。这些发现对于理解干旱和半干旱草原中微生物介导的碳循环过程具有重要意义。
