Peatlands, some of the Earth’s most vital carbon reservoirs, are increasingly threatened as global warming accelerates and regional drying becomes more common. These unique ecosystems store vast amounts of carbon accumulated over thousands of years, playing a critical role in regulating the global climate.
A new study, led by an international team of researchers including scientists from the University of Exeter, reveals that peatlands may have an inherent natural defense against drying conditions an ancient cooperation between woody plants and soil microbes.
Published in Nature Communications , the research focuses on a subtropical peatland in southern China, where historic periods of drought have occurred. The study shows that during these dry phases, an expansion of woody plants altered the quality of organic matter in the peat, making it more resistant to decomposition. Simultaneously, microbial activity that breaks down organic carbon was suppressed. This synergy between plants and microbes helped to safeguard the peatland’s carbon stores at times when they might otherwise have been released into the atmosphere.
Dr. Yiming Zhang, Senior Research Associate at the University of Bristol and lead author, explained, “Woody plants didn’t just survive the drying climate — they actively helped build resilience. Their organic inputs made the peat chemically tougher to degrade, and microbes adapted by slowing their metabolism, reducing carbon loss. This feedback mechanism was stronger than we previously understood.”
To reach these conclusions, the team used a combination of cutting-edge techniques, including plant macrofossil analysis, microbial lipid biomarkers, and compound-specific carbon and hydrogen isotope analysis. These methods allowed the reconstruction of ecological changes in the Zhaogongting peatland over the past 14,000 years. The researchers discovered that during a mid-Holocene drying event about 8,000 to 6,000 years ago, woody plants quickly expanded, replacing grasses but still coexisting with mosses. This vegetation shift transformed the peat’s organic makeup: carbohydrates became less common, while aromatic compounds increased, creating a more chemically complex and less decomposable carbon pool. In response, microbial communities reduced heterotrophic activity (which breaks down organic material) and may have shifted toward autotrophic metabolism (self-feeding).
These combined changes corresponded with a remarkable peak in carbon accumulation during the drying period, with rates nearly three times higher than during wet times. Professor Angela Gallego-Sala, a biogeochemist at the University of Exeter and co-author, said, “Peatlands are resilient ecosystems with unique feedback mechanisms. This study uncovers a previously unknown process that helps protect peatlands under warmer and drier conditions, with important implications for their future amid climate change.”
Professor Rich Pancost of the University of Bristol’s Cabot Institute added, “Peatland vegetation is highly sensitive to climate shifts. Our work reveals how these changes significantly affect the composition and reactivity of organic matter, shedding light on the complex interplay between climate change, ecology, and carbon cycling.” However, the study also warns that this protective plant-microbe feedback likely has limits. Dr. Zhang, who began this research during his postdoctoral work at China University of Geosciences, noted, “Woody plant expansion does not guarantee endless carbon storage. There may be ecological tipping points beyond which peatlands transition to very different ecosystems, potentially triggering renewed carbon release.”
The team emphasizes the need for further research to better understand how peatlands respond to climate-driven changes, especially in tropical regions and areas where peatlands have been degraded. The paper, “Microbial responses to changing plant communities protect peatland carbon stores during Holocene drying,” offers crucial insights into natural resilience mechanisms that could help guide peatland conservation efforts in a warming world.
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