Metallic protection of soil carbon: Divergent drainage effects in Sphagnum vs. non-Sphagnum wetlands

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  • Chengzhu Liu
    Chinese Academy of Sciences, Beijing
  • Yunpeng Zhao
    Chinese Academy of Sciences, Beijing
  • Lixiao Ma
    Chinese Academy of Sciences, Beijing
  • Guoqing Zhai
    Chinese Academy of Sciences, Beijing
  • Xingqi Li
    Chinese Academy of Sciences, Beijing
  • Chris Freeman
  • Xiaojuan Feng
    Chinese Academy of Sciences, Beijing
The established paradigm assumes that drainage may decrease the vast soil organic carbon (SOC) reservoir in global wetlands. Yet drainage can also promote SOC stabilization by fostering the accrual of metal-bound organic carbon (bound OC) upon oxygen exposure. Here, this emergent mechanism is tested for the first time at a regional scale, using literature data and a nationwide, pairwise survey of drained wetlands across China. We show that long-term (15–55 years) drainage largely increased metallic protection of SOC (bound OC%) in non-Sphagnum wetlands, but consistently decreased bound OC% in Sphagnum wetlands following replacement of the ‘rust engineer’ Sphagnum by herbaceous plants. Improved SOC stock estimates based on 66 soil profiles reveal that bound OC increases can compensate for the loss of unbound SOC components in non-Sphagnum wetlands with substantial accrual of reactive metals. Metallic stabilization of wetland SOC is hence a widespread but overlooked mechanism that is heavily influenced by vegetational shifts. Incorporating this novel mechanism into models will improve prediction of wetland SOC dynamics under shifting hydrological regimes.
Original languageEnglish
Pages (from-to)nwae178
JournalNational Science Review
Early online date20 May 2024
DOIs
Publication statusE-pub ahead of print - 20 May 2024
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