Deep soil microbial carbon use efficiency responds stronger to nitrogen deposition than top soil in tropical forests, southern China

Yamin Jiang, Tianyan Su, Huafeng Wang, Qiu Yang, Jingli Lu, Qunyou Fu, Han Mao, Wenxian Xu, Yiqi Luo, Wenjie Liu, Huai Yang, Mengyang Fang

Research output: Contribution to journalArticlepeer-review


Background and aims: Soil microbial carbon use efficiency (CUE), a key parameter determining soil C fate, has been associated with soil nitrogen (N) availability. However, the responses of forest soil CUE to aggregated N deposition are not clear. Moreover, it remains unclear whether responses may be mediated by soil depth. It is crucial to investigate the patterns and drivers of CUE with N deposition in forest top and deep soil. Methods: This study examined the responses of microbial CUE to short-term N addition treatments in the top (0–10 cm) and deep (60–80 cm) soils from two tropical forests in Hainan, southern China. Additionally, a meta-analysis was conducted to reveal a global pattern of forest soil microbial CUE response to N deposition. Results: The addition of N in the two tropical forests did not change topsoil CUE, whereas deep soil CUE increased by 25.5% (0.44 and 0.55 without and with N addition) on average. In the two soil depths, changes in CUE to N addition were negatively correlated with Fungi: Bacteria ratio (F: B). The negative relationship between resource limitation and CUE was found to be present with C limitation in top soil and N limitation in deep soil. N cycling enzyme activities played a vital role in regulating microbial resource limitation and CUE. The decrease in F: B and C: N ratios with the addition of N partly explained the stronger response of CUE in deep soil. At the global scale, the addition of N had no effect on the forest top soil CUE. However, the significant decline in pH and microbial biomass carbon with N deposition could reduce microbial CUE. Conclusion: The addition of N facilitated carbon storage in deep soil but had no effects on topsoil carbon storage in a tropical forest. Our results highlighted that the soil depth-driven variation in soil C: N and F: B can regulate microbial CUE, which could provide a basis for understanding the soil C cycle in tropical forest ecosystems.

Original languageEnglish (US)
JournalPlant and Soil
StateAccepted/In press - 2024
Externally publishedYes


  • CUE
  • Eco-enzymatic stoichiometric model
  • Labeled substrate
  • Nitrogen addition
  • Phospholipid fatty acids

ASJC Scopus subject areas

  • Soil Science
  • Plant Science


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