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<p>Soil microbial communities play critical roles in carbon cycling, yet their responses to elevated carbon dioxide (CO<sub>2</sub>) and ozone (O<sub>3</sub>) remain poorly understood under field conditions. This study assessed microbial community structure and functional diversity in wheat (<i>Triticum aestivum</i> L.) agroecosystem exposed to elevated CO<sub>2</sub> (EC), elevated O<sub>3</sub> (EO), and their combination (ECO).&#xa0;The study was conducted over two growing seasons in a Free-Air O<sub>3</sub> and CO<sub>2</sub> Enrichment (FAOCE) facility. Microbial community structure was evaluated using phospholipid fatty acid (PLFA) profiling. Functional diversity was assessed through community-level physiological profiling (CLPP) using Biolog EcoPlates. Microbial diversity indices (Shannon-Wiener, Simpson, and evenness) and principal component analysis (PCA) were used to examine treatment effects.&#xa0;Under EC, total PLFA content and microbial biomass increased significantly, accompanied by greater abundance of Gram-negative bacteria and fungi, indicating enhanced microbial activity and carbon turnover. In contrast, EO reduced microbial biomass and metabolic activity, suggesting suppression of microbial functioning under oxidative stress. ECO showed intermediate responses, where EC partially mitigated EO-induced reductions. The Shannon diversity index increased under EC by 8.5% (<i>p</i> &lt; 0.01; <i>n</i> = 3) and 6% (<i>p</i> &lt; 0.01; <i>n</i> = 3) across two years, and under ECO by 3.6% (<i>n</i> = 3) and 5.1% (<i>p</i> &lt; 0.01; <i>n</i> = 3), whereas EO caused declines of 6.5% and 5.07%, respectively. PCA of PLFA and CLPP data showed clear separation of treatments, with EC and ECO exhibiting positive dispersion.&#xa0;These findings indicate that prolonged EC exposure may enhance soil carbon sequestration potential through increased microbial biomass and functional diversity, whereas EO-induced reductions in microbial activity could constrain these processes. The results emphasize the interactive controls of atmospheric drivers on soil carbon dynamics and their implications for microbial carbon use efficiency (CUE) with significant implications for maintaining soil fertility under future climate scenarios.</p> Graphical Abstract <p></p>

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Soil Microbial Diversity and Function Respond Contrastingly to Elevated CO2 and Ozone with Implications for Carbon Sequestration in Wheat Cultivation

  • 期刊论文

  • 发表日期：

    2026年7月29日

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  • Bhawana Joshi,
  • Arti Bhatia,
  • Namita Das Saha,
  • Achhelal Yadav,
  • Govindaraj Kamalam Dinesh,
  • Ajit Varma,
  • Swati Tripathi,
  • Anita Chaudhary

摘要

Soil microbial communities play critical roles in carbon cycling, yet their responses to elevated carbon dioxide (CO2) and ozone (O3) remain poorly understood under field conditions. This study assessed microbial community structure and functional diversity in wheat (Triticum aestivum L.) agroecosystem exposed to elevated CO2 (EC), elevated O3 (EO), and their combination (ECO). The study was conducted over two growing seasons in a Free-Air O3 and CO2 Enrichment (FAOCE) facility. Microbial community structure was evaluated using phospholipid fatty acid (PLFA) profiling. Functional diversity was assessed through community-level physiological profiling (CLPP) using Biolog EcoPlates. Microbial diversity indices (Shannon-Wiener, Simpson, and evenness) and principal component analysis (PCA) were used to examine treatment effects. Under EC, total PLFA content and microbial biomass increased significantly, accompanied by greater abundance of Gram-negative bacteria and fungi, indicating enhanced microbial activity and carbon turnover. In contrast, EO reduced microbial biomass and metabolic activity, suggesting suppression of microbial functioning under oxidative stress. ECO showed intermediate responses, where EC partially mitigated EO-induced reductions. The Shannon diversity index increased under EC by 8.5% (p < 0.01; n = 3) and 6% (p < 0.01; n = 3) across two years, and under ECO by 3.6% (n = 3) and 5.1% (p < 0.01; n = 3), whereas EO caused declines of 6.5% and 5.07%, respectively. PCA of PLFA and CLPP data showed clear separation of treatments, with EC and ECO exhibiting positive dispersion. These findings indicate that prolonged EC exposure may enhance soil carbon sequestration potential through increased microbial biomass and functional diversity, whereas EO-induced reductions in microbial activity could constrain these processes. The results emphasize the interactive controls of atmospheric drivers on soil carbon dynamics and their implications for microbial carbon use efficiency (CUE) with significant implications for maintaining soil fertility under future climate scenarios.

Graphical Abstract