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<p>Thermokarst lakes represent significant sources of carbon emissions formed through permafrost degradation. However, peatland development at their margins can shift this climate feedback from positive to negative. Understanding the mechanisms driving such peatland development is therefore crucial for interpreting both past and future global carbon cycles. In this study, we analysed seven peat cores from a permafrost peatland located at a thermokarst lake margin in the northern Greater Khingan Mountains, a region highly sensitive to global change. Using palynological data, we quantitatively reconstructed local vegetation cover and evaluated the effects of autogenic and allogenic factors on peatland evolution over the past 70&#xa0;years. Peat initiation began at ~ 1,300&#xa0;yr <span>bp</span> through the lateral expansion of floating vegetation mats and vertical sediment accumulation, representing a lake terrestrialisation process. Adequate moisture conditions sustained long-term fen development over the past millennium. However, drought induced by rapid climate warming triggered a drying trend at the thermokarst lake margin since 1980 <span>ce</span>, culminating in a transition from a Cyperaceae-dominated fen to an Ericaceae–<i>Sphagnum</i>-dominated bog after 2000 <span>ce</span>. <i>Sphagnum</i> expansion enhanced peat and carbon accumulation rates following this transition. The fen–bog transition was initiated primarily by large-scale climatic change in the 1980s and subsequently accelerated by autogenic vegetation succession since the 2000s. Our findings underscore the importance of thermokarst lake-margin permafrost peatlands within the global carbon cycle and provide new insights into peatland–climate feedback mechanisms.</p>

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Autogenic and climatic drivers of vegetation succession in a thermokarst lake-margin peatland, northern Greater Khingan Mountains

  • 期刊论文

  • 发表日期：

    2026年5月23日

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  • Dongxue Han,
  • Jiangtao Gao,
  • Jinxin Cong,
  • Guoping Wang,
  • Chuanyu Gao

摘要

Thermokarst lakes represent significant sources of carbon emissions formed through permafrost degradation. However, peatland development at their margins can shift this climate feedback from positive to negative. Understanding the mechanisms driving such peatland development is therefore crucial for interpreting both past and future global carbon cycles. In this study, we analysed seven peat cores from a permafrost peatland located at a thermokarst lake margin in the northern Greater Khingan Mountains, a region highly sensitive to global change. Using palynological data, we quantitatively reconstructed local vegetation cover and evaluated the effects of autogenic and allogenic factors on peatland evolution over the past 70 years. Peat initiation began at ~ 1,300 yr bp through the lateral expansion of floating vegetation mats and vertical sediment accumulation, representing a lake terrestrialisation process. Adequate moisture conditions sustained long-term fen development over the past millennium. However, drought induced by rapid climate warming triggered a drying trend at the thermokarst lake margin since 1980 ce, culminating in a transition from a Cyperaceae-dominated fen to an Ericaceae–Sphagnum-dominated bog after 2000 ce. Sphagnum expansion enhanced peat and carbon accumulation rates following this transition. The fen–bog transition was initiated primarily by large-scale climatic change in the 1980s and subsequently accelerated by autogenic vegetation succession since the 2000s. Our findings underscore the importance of thermokarst lake-margin permafrost peatlands within the global carbon cycle and provide new insights into peatland–climate feedback mechanisms.