Background Temperature sensitivity (Q10) of soil organic matter decomposition is a critical metric for predicting global soil carbon responses to warming. Moso bamboo (Phyllostachys edulis) often expands quickly into neighboring Chinese fir (Cunninghamia lanceolata) forests and substantially alters soil carbon cycling. However, the mechanisms underlying the effects of Moso bamboo expansion on Q10 remain unclear. Methods We performed a 336-day incubation experiment using Ferralsolic soils (0–20 cm) from three sites to assess Q10 shifts caused by bamboo expansion. To identify determinants of Q10 variability, we evaluated substrate quality, microbial properties, aggregate protection, and mineral protection. Results Bulk-soil Q10 was 31.0% and 28.8% greater in mixed Moso bamboo and Chinese fir forests (MF) than in pure Moso bamboo (BF) and Chinese fir (CF) forests, respectively (p < 0.001), which mainly stemmed from elevated Q10 of the recalcitrant carbon pool. The poorer substrate quality observed in MF explained its enhanced Q10, consistent with the carbon quality–temperature hypothesis. The microbial abundance and the fungal proportion were higher in MF than in BF and CF, further increasing Q10. In addition, the decline in carbon stored within micro-aggregates (0.053–0.25 mm) in MF indicated weaker aggregate protection, which contributed to its elevated Q10. Among all determinants, aggregate protection was the dominant factor explaining variation in bulk-soil Q10. Conclusion Collectively, weaker aggregate protection is the principal mechanism underlying the higher Q10 in MF. These findings provide a scientific basis for the ecological management of bamboo forests aimed at mitigating climate change. Graphical Abstract Conceptual diagram illustrating the mechanisms by which Moso bamboo expansion influences the temperature sensitivity (Q10) of soil organic matter decomposition. The roles of four types of determinants in driving Q10 variation were investigated. The width of each red arrow represents the relative importance of a specific determinant in influencing Q10. Symbols ‘ + ’ and ‘ − ’ denote positive and negative effects, respectively, of specific determinants on Q10 during the expansion of Moso bamboo into Chinese fir forests. Determinants enclosed in the dashed-line box were found to have no significant effect on Q10 variation. Abbreviations: BF, pure Moso bamboo forests; C, carbon; CF, pure Chinese fir forests; MF, mixed Moso bamboo and Chinese fir forests.

Aggregate protection dominates the variation in soil organic matter temperature sensitivity induced by the expansion of Moso bamboo into Chinese fir forests

期刊论文
发表日期：

2025年10月31日

查看全文

Xiaotong Liu,
Shaohui Fan,
Zhoubin Huang,
Jiajun Liu,
Wenhui Su,
Guopeng Liang,
Guanglu Liu

摘要

Background

Temperature sensitivity (Q₁₀) of soil organic matter decomposition is a critical metric for predicting global soil carbon responses to warming. Moso bamboo (Phyllostachys edulis) often expands quickly into neighboring Chinese fir (Cunninghamia lanceolata) forests and substantially alters soil carbon cycling. However, the mechanisms underlying the effects of Moso bamboo expansion on Q₁₀ remain unclear.

Methods

We performed a 336-day incubation experiment using Ferralsolic soils (0–20 cm) from three sites to assess Q₁₀ shifts caused by bamboo expansion. To identify determinants of Q₁₀ variability, we evaluated substrate quality, microbial properties, aggregate protection, and mineral protection.

Results

Bulk-soil Q₁₀ was 31.0% and 28.8% greater in mixed Moso bamboo and Chinese fir forests (MF) than in pure Moso bamboo (BF) and Chinese fir (CF) forests, respectively (p < 0.001), which mainly stemmed from elevated Q₁₀ of the recalcitrant carbon pool. The poorer substrate quality observed in MF explained its enhanced Q₁₀, consistent with the carbon quality–temperature hypothesis. The microbial abundance and the fungal proportion were higher in MF than in BF and CF, further increasing Q₁₀. In addition, the decline in carbon stored within micro-aggregates (0.053–0.25 mm) in MF indicated weaker aggregate protection, which contributed to its elevated Q₁₀. Among all determinants, aggregate protection was the dominant factor explaining variation in bulk-soil Q₁₀.

Conclusion

Collectively, weaker aggregate protection is the principal mechanism underlying the higher Q₁₀ in MF. These findings provide a scientific basis for the ecological management of bamboo forests aimed at mitigating climate change.

Graphical Abstract

Conceptual diagram illustrating the mechanisms by which Moso bamboo expansion influences the temperature sensitivity (Q₁₀) of soil organic matter decomposition. The roles of four types of determinants in driving Q₁₀ variation were investigated. The width of each red arrow represents the relative importance of a specific determinant in influencing Q₁₀. Symbols ‘ + ’ and ‘ − ’ denote positive and negative effects, respectively, of specific determinants on Q₁₀ during the expansion of Moso bamboo into Chinese fir forests. Determinants enclosed in the dashed-line box were found to have no significant effect on Q₁₀ variation. Abbreviations: BF, pure Moso bamboo forests; C, carbon; CF, pure Chinese fir forests; MF, mixed Moso bamboo and Chinese fir forests.