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Aims <p>To assess how + 5&#xa0;°C soil warming affects nitrogen (N) dynamics in early-stage subtropical forests, we compared Chinese fir plantations and natural regeneration. The hypothesis was that warming accelerates N mineralization and nitrification, increasing risks of leaching and gaseous losses where sapling N uptake is limited.</p> Methods <p>A warming experiment was conducted in subtropical China using buried heating cables (+ 5&#xa0;°C), incorporating treatments of Chinese fir (<i>Cunninghamia lanceolata</i>) plantation and natural regeneration.</p> Results <p>Warming significantly increased annual net N mineralization and nitrification in plantations (except in August) and in natural regeneration during January. In plantations, warming elevated DON, NO<sub>3</sub><sup>−</sup>-N, and NH<sub>4</sub><sup>+</sup>-N in surface soil (0–10&#xa0;cm), as well as NO<sub>3</sub><sup>−</sup>-N throughout the 0–60&#xa0;cm profile, particularly in January. In contrast, NH<sub>4</sub><sup>+</sup>-N decreased in natural regeneration in August. Warming also increased NO<sub>3</sub><sup>−</sup>-N concentrations in leachate and elevated N<sub>2</sub>O emissions across both natural regeneration and plantation plots. The abundance of functional genes related to N cycling declined under warming, although natural regeneration maintained higher levels of denitrification genes (<i>narG</i>, <i>nirK</i>, <i>nosZ</i>) and the N-fixation gene (<i>nifH</i>) compared to plantations. Enrichment of δ<sup>15</sup>N in N-rich plant organs further reflected enhanced soil N transformation under warming.</p> Conclusion <p>Warming induced a more open soil N cycle in subtropical forests, with greater N leaching in plantations than in natural regeneration during early warming years. This highlights the importance of forest management and the value of near-natural practices under climate change.</p>

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Differential effects of soil warming on nitrogen dynamics in plantation and natural regeneration subtropical forests during the initial warming years

  • 期刊论文

  • 发表日期：

    2025年7月21日

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  • Dongmei Wan,
  • Zhijie Yang,
  • Shidong Chen

摘要

Aims

To assess how + 5 °C soil warming affects nitrogen (N) dynamics in early-stage subtropical forests, we compared Chinese fir plantations and natural regeneration. The hypothesis was that warming accelerates N mineralization and nitrification, increasing risks of leaching and gaseous losses where sapling N uptake is limited.

Methods

A warming experiment was conducted in subtropical China using buried heating cables (+ 5 °C), incorporating treatments of Chinese fir (Cunninghamia lanceolata) plantation and natural regeneration.

Results

Warming significantly increased annual net N mineralization and nitrification in plantations (except in August) and in natural regeneration during January. In plantations, warming elevated DON, NO3−-N, and NH4+-N in surface soil (0–10 cm), as well as NO3−-N throughout the 0–60 cm profile, particularly in January. In contrast, NH4+-N decreased in natural regeneration in August. Warming also increased NO3−-N concentrations in leachate and elevated N2O emissions across both natural regeneration and plantation plots. The abundance of functional genes related to N cycling declined under warming, although natural regeneration maintained higher levels of denitrification genes (narG, nirK, nosZ) and the N-fixation gene (nifH) compared to plantations. Enrichment of δ15N in N-rich plant organs further reflected enhanced soil N transformation under warming.

Conclusion

Warming induced a more open soil N cycle in subtropical forests, with greater N leaching in plantations than in natural regeneration during early warming years. This highlights the importance of forest management and the value of near-natural practices under climate change.