Climate warming and elevated CO<sub>2</sub> alter peatland soil carbon sources and stability.

Ofiti, Nicholas O E; Schmidt, Michael W I; Abiven, Samuel; Hanson, Paul J; Iversen, Colleen M; Wilson, Rachel M; Kostka, Joel E; Wiesenberg, Guido L B et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

Peatlands are an important carbon (C) reservoir storing one-third of global soil organic carbon (SOC), but little is known about the fate of these C stocks under climate change. Here, we examine the impact of warming and elevated atmospheric CO<sub>2</sub> concentration (eCO<sub>2</sub>) on the molecular composition of SOC to infer SOC sources (microbe-, plant- and fire-derived) and stability in a boreal peatland. We show that while warming alone decreased plant- and microbe-derived SOC due to enhanced decomposition, warming combined with eCO<sub>2</sub> increased plant-derived SOC compounds. We further observed increasing root-derived inputs (suberin) and declining leaf/needle-derived inputs (cutin) into SOC under warming and eCO<sub>2</sub>. The decline in SOC compounds with warming and gains from new root-derived C under eCO<sub>2</sub>, suggest that warming and eCO<sub>2</sub> may shift peatland C budget towards pools with faster turnover. Together, our results indicate that climate change may increase inputs and enhance decomposition of SOC potentially destabilising C storage in peatlands.