Dual Controls on Carbon Loss During Drought in Peatlands


Peatlands store a third of global soil carbon. Drought and drainage coupled with climate warming present the main threat to these stores. Hence, understanding drought effects and inherent feedbacks related to peat decomposition has been a primary global challenge. However, widely divergent results in recent studies concerning drought effects challenge the accepted paradigm that waterlogging and associated anoxia are the overarching controls locking up carbon stored in peat. By linking field and microcosm experiments, a recent study shows how previously unrecognized mechanisms regulate the buildup of phenolics, which protects stored carbon directly by reducing phenol oxidase activity during short-term drought and, indirectly, through a shift from low-phenolic Sphagnum and herbs to high-phenolic shrubs after long-term moderate drought. The study demonstrates that shrub expansion induced by drought and warming in boreal peatlands might be a long-term, self-adaptive mechanism not only increasing carbon sequestration but also potentially protecting historic soil carbon. The researchers propose that the projected “positive feedback loop” between carbon emissions and drought in peatlands may not occur in the long term.


Wang, H., C. J. Richardson, and M. Ho. 2015. “Dual Controls on Carbon Loss During Drought in Peatlands,” Nature Climate Change 5(6), 584–87. DOI: 10.1038/nclimate2643.