Chen Minghao, Zhou Shuyidan, Xiang Ping, Wang Yutao, Luo Xianzhen, Zhang Xiaofeng, Wen Dazhi
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Science, Guangzhou, 510650, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China.
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Science, Guangzhou, 510650, China.
J Environ Manage. 2024 Feb;351:120012. doi: 10.1016/j.jenvman.2023.120012. Epub 2024 Jan 2.
Soil microbes are fundamental to ecosystem health and productivity. How soil microbial communities are influenced by elevated atmospheric carbon dioxide (eCO) concentration and nitrogen (N) deposition under heavy metal pollution remains uncertain, despite global exposure of terrestrial ecosystems to eCO, high N deposition and heavy metal stress. Here, we conducted a four year's open-top chamber experiment to assess the effects of soil cadmium (Cd) treatment (10 kg hm year) alone and combined treatments of Cd with eCO concentration (700 ppm) and/or N addition (100 kg hm year) on tree growth and rhizosphere microbial community. Relative to Cd treatment alone, eCO concentration in Cd contaminated soil increased the complexity of microbial networks, including the number links, average degree and positive/negative ratios. The combined effect of eCO and N addition in Cd contaminated soil not only increased the complexity of microbial networks, but also enhanced the abundance of microbial urealysis related UreC and nitrifying related amoA1 and amoA2, and the richness of arbuscular mycorrhiza fungi (AMF), thereby improving the symbiotic functions between microorganisms and plants. Results from correlation analysis and structural equation model (SEM) further demonstrated that eCO concentration and N addition acted on functions and networks differently. Elevated CO positively regulated microbial networks and functions through phosphorus (P) and Cd concentration in roots, while N addition affected microbial functions through soil available N and soil organic carbon (SOC) concentration and microbial network through soil Cd concentration. Overall, our findings highlight that eCO concentration and N addition make microbial communities towards ecosystem health that may mitigate Cd stress, and provide new insights into the microbiology supporting phytoremediation for Cd contaminated sites in current and future global change scenarios.
土壤微生物对于生态系统健康和生产力至关重要。尽管陆地生态系统普遍面临大气二氧化碳浓度升高（eCO）、高氮沉降和重金属胁迫，但在重金属污染情况下，土壤微生物群落如何受到eCO浓度升高和氮（N）沉降的影响仍不确定。在此，我们进行了一项为期四年的开顶式气室实验，以评估土壤镉（Cd）处理（10 kg hm⁻²年⁻¹）单独以及Cd与eCO浓度（700 ppm）和/或氮添加（100 kg hm⁻²年⁻¹）联合处理对树木生长和根际微生物群落的影响。相对于单独的Cd处理，Cd污染土壤中的eCO浓度增加了微生物网络的复杂性，包括连接数、平均度和正/负比率。Cd污染土壤中eCO和氮添加的联合作用不仅增加了微生物网络的复杂性，还提高了与微生物尿素分解相关的UreC以及与硝化作用相关的amoA1和amoA2的丰度，以及丛枝菌根真菌（AMF）的丰富度，从而改善了微生物与植物之间的共生功能。相关性分析和结构方程模型（SEM）的结果进一步表明，eCO浓度和氮添加对功能和网络的作用方式不同。升高的CO通过根系中的磷（P）和Cd浓度对微生物网络和功能进行正向调节，而氮添加则通过土壤有效氮和土壤有机碳（SOC）浓度影响微生物功能，并通过土壤Cd浓度影响微生物网络。总体而言，我们的研究结果表明，eCO浓度和氮添加使微生物群落朝着有利于生态系统健康的方向发展，这可能减轻Cd胁迫，并为当前和未来全球变化情景下支持Cd污染场地植物修复的微生物学提供新的见解。
