Scholarlink

Aims <p>Climate change, driven by elevated atmospheric CO₂ and warming, significantly influences soil organic carbon (SOC) dynamics, yet its combined effects on SOC accumulation, stability, and underlying mechanisms—particularly across soil profiles—remain poorly understood.&#xa0;This study aims to quantify the individual and interactive effects of elevated CO₂ and warming on SOC accumulation, stability, and their controlling factors across the 0–100&#xa0;cm soil profile in a subtropical paddy, based free-air CO₂ enrichment (FACE) experiment for 12&#xa0;years.</p> Methods <p>We conducted a decadal-scale FACE experiment in a rice paddy. Four treatments were applied: ambient conditions (CK), elevated CO₂ (600 ± 20&#xa0;ppm, CE), canopy warming (+ 2&#xa0;°C, W), and their combination (CW). Soil samples were collected from 0–100&#xa0;cm depth to analyze SOC content, fractions (labile and recalcitrant), and stability indices. Statistical and modeling approaches, including random forest analysis, were used to identify controlling factors of SOC dynamics.</p> Results <p>Net SOC storage&#xa0;in the 0–100&#xa0;cm soil profile&#xa0;by 20.3&#xa0;Mg&#xa0;ha<sup>−1</sup> under elevated CO<sub>2</sub> alone but decreased by 13.0&#xa0;Mg&#xa0;ha<sup>−1</sup> with warming alone. The combined effect of elevated CO<sub>2</sub> and warming was a loss on SOC stocks of 6.23&#xa0;Mg&#xa0;ha<sup>−1</sup>. Elevated CO<sub>2</sub> increased the recalcitrant organic carbon fraction (ROC, especially above 20&#xa0;cm) and decreased the labile organic carbon fraction (LOC, especially below 20&#xa0;cm). Warming alone slightly decreased ROC but significantly decreased LOC. The carbon pool management index (CPMI) declined under all climate change treatments, indicating a reduction in SOC pool quality, with warming exerting a stronger negative effect than elevated CO₂. Random forest analysis highlighted the pivotal roles of vegetation, soil and microbial processes in SOC dynamics. Soil chemical properties were more important than soil physical properties, and microbal necromass C made a more important contribution to SOC than plant quality and quantity.</p> Conclusions <p>This site-level study suggests that under future climate scenarios, the tested paddy soil may act as a net C sink under elevated CO₂ but as a net C source under warming. These contrasting responses highlight the need for further research across diverse sites to accurately predict regional C dynamics in subtropical paddy systems.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Elevated CO2 has a greater impact on surface soil carbon but warming on subsoil carbon: evidence from SOC accumulation and stability

  • 期刊论文

  • 发表日期：

    2026年1月6日

查看全文
  • Yaran Fan,
  • Bingbing Yu,
  • Shaopan Xia,
  • Ziqi Zhu,
  • Lukas Van Zwieten,
  • Yufei Zhong,
  • Aoxue Cai,
  • Ran Wang,
  • Zhaoliang Song,
  • Wei Yang,
  • Yuchuan Fan,
  • Xiaoyu Liu,
  • Xuhui Zhang,
  • Jufeng Zheng

摘要

Aims

Climate change, driven by elevated atmospheric CO₂ and warming, significantly influences soil organic carbon (SOC) dynamics, yet its combined effects on SOC accumulation, stability, and underlying mechanisms—particularly across soil profiles—remain poorly understood. This study aims to quantify the individual and interactive effects of elevated CO₂ and warming on SOC accumulation, stability, and their controlling factors across the 0–100 cm soil profile in a subtropical paddy, based free-air CO₂ enrichment (FACE) experiment for 12 years.

Methods

We conducted a decadal-scale FACE experiment in a rice paddy. Four treatments were applied: ambient conditions (CK), elevated CO₂ (600 ± 20 ppm, CE), canopy warming (+ 2 °C, W), and their combination (CW). Soil samples were collected from 0–100 cm depth to analyze SOC content, fractions (labile and recalcitrant), and stability indices. Statistical and modeling approaches, including random forest analysis, were used to identify controlling factors of SOC dynamics.

Results

Net SOC storage in the 0–100 cm soil profile by 20.3 Mg ha−1 under elevated CO2 alone but decreased by 13.0 Mg ha−1 with warming alone. The combined effect of elevated CO2 and warming was a loss on SOC stocks of 6.23 Mg ha−1. Elevated CO2 increased the recalcitrant organic carbon fraction (ROC, especially above 20 cm) and decreased the labile organic carbon fraction (LOC, especially below 20 cm). Warming alone slightly decreased ROC but significantly decreased LOC. The carbon pool management index (CPMI) declined under all climate change treatments, indicating a reduction in SOC pool quality, with warming exerting a stronger negative effect than elevated CO₂. Random forest analysis highlighted the pivotal roles of vegetation, soil and microbial processes in SOC dynamics. Soil chemical properties were more important than soil physical properties, and microbal necromass C made a more important contribution to SOC than plant quality and quantity.

Conclusions

This site-level study suggests that under future climate scenarios, the tested paddy soil may act as a net C sink under elevated CO₂ but as a net C source under warming. These contrasting responses highlight the need for further research across diverse sites to accurately predict regional C dynamics in subtropical paddy systems.