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Background <p>Global warming has significantly increased the frequency and scale of wildfires. However, the effects of fire residues on soil CO₂ emissions and the germination of pioneer species in burned areas have been insufficiently studied. Understanding these impacts is crucial for post-fire ecosystem recovery. This study examined the effects of wildfire ash from Liangshan Yi Autonomous Prefecture, China, on the germination of <i>Digitaria sanguinalis (L.) Scop</i> and soil respiration (<i>R</i>s).</p> Results <p>Within the applied ash gradient (0.00, 0.58, 1.16, 1.73&#xa0;kg&#xa0;m<sup>−2</sup>), final germination of <i>Digitaria sanguinalis</i> was not significantly affected by ash, whereas precipitation exerted the dominant control. In contrast, early seedling growth showed a significant ash × precipitation interaction: under normal to moderately wet conditions, intermediate ash loading (≈0.58 and 1.16&#xa0;kg&#xa0;m<sup>−2</sup>) promoted plant height, but this effect disappeared under the driest or wettest scenarios. Across all precipitation regimes, <i>R</i>s increased with ash loading and showed an early rise, a mid-term peak, and a later stabilization or decline as ash-derived substrates were depleted. <i>R</i>s was strongly related to 5 cm soil temperature, whereas, no significant monotonic association between Rs and 5 cm soil moisture was detected within the moisture conditions maintained by the precipitation treatments, suggesting that temperature explained more of the short-term variability in Rs. The temperature sensitivity (<i>Q</i><sub>10</sub>) of <i>R</i>s also increased with ash addition, with values of 1.30, 1.82, 2.18, and 2.34 for the four ash treatments.</p> Conclusions <p>Wildfire ash within a realistic post-fire range did not significantly inhibit the germination of the pioneer grass <i>D. sanguinalis</i>, which was mainly controlled by precipitation, but moderate ash loading (0.58, 1.16&#xa0;kg&#xa0;m<sup>−2</sup>) supported early seedling growth under adequate moisture. At the same time, ash inputs enhanced <i>R</i>s and increased its apparent temperature sensitivity, with <i>R</i>s being predominantly driven by soil temperature and with moisture effects not emerging as a detectable monotonic trend within the experimental moisture window. These findings suggest that, in water-limited dry-valley ecosystems, complete removal of surface ash to avoid potential germination inhibition is unnecessary; instead, management should prioritize maintaining soil moisture while allowing moderate ash to remain on the surface to support early post-fire recovery and to improve the representation of ash effects in soil respiration models for fire-affected forests.</p>

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Responsess of Digitaria sanguinalis (L.) Scop growth and soil respiration dynamics to ash content in a burned area

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年4月21日

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  • Huanhuan Qi,
  • Fachao Qin,
  • Honghu Wang,
  • Bin Zhang,
  • Jun Luo,
  • Hui Liu,
  • Haiqing Yang,
  • Qingchun Deng,
  • Dinghui Xu,
  • Xuejun Cheng,
  • Haijun Ouyang

摘要

Background

Global warming has significantly increased the frequency and scale of wildfires. However, the effects of fire residues on soil CO₂ emissions and the germination of pioneer species in burned areas have been insufficiently studied. Understanding these impacts is crucial for post-fire ecosystem recovery. This study examined the effects of wildfire ash from Liangshan Yi Autonomous Prefecture, China, on the germination of Digitaria sanguinalis (L.) Scop and soil respiration (Rs).

Results

Within the applied ash gradient (0.00, 0.58, 1.16, 1.73 kg m−2), final germination of Digitaria sanguinalis was not significantly affected by ash, whereas precipitation exerted the dominant control. In contrast, early seedling growth showed a significant ash × precipitation interaction: under normal to moderately wet conditions, intermediate ash loading (≈0.58 and 1.16 kg m−2) promoted plant height, but this effect disappeared under the driest or wettest scenarios. Across all precipitation regimes, Rs increased with ash loading and showed an early rise, a mid-term peak, and a later stabilization or decline as ash-derived substrates were depleted. Rs was strongly related to 5 cm soil temperature, whereas, no significant monotonic association between Rs and 5 cm soil moisture was detected within the moisture conditions maintained by the precipitation treatments, suggesting that temperature explained more of the short-term variability in Rs. The temperature sensitivity (Q10) of Rs also increased with ash addition, with values of 1.30, 1.82, 2.18, and 2.34 for the four ash treatments.

Conclusions

Wildfire ash within a realistic post-fire range did not significantly inhibit the germination of the pioneer grass D. sanguinalis, which was mainly controlled by precipitation, but moderate ash loading (0.58, 1.16 kg m−2) supported early seedling growth under adequate moisture. At the same time, ash inputs enhanced Rs and increased its apparent temperature sensitivity, with Rs being predominantly driven by soil temperature and with moisture effects not emerging as a detectable monotonic trend within the experimental moisture window. These findings suggest that, in water-limited dry-valley ecosystems, complete removal of surface ash to avoid potential germination inhibition is unnecessary; instead, management should prioritize maintaining soil moisture while allowing moderate ash to remain on the surface to support early post-fire recovery and to improve the representation of ash effects in soil respiration models for fire-affected forests.