Glob. Change Biol. (2019).

Approximately 500 gigatons of carbon are stored in northern peatlands. Because subsurface aeration plays a significant role in peatland carbon cycling, understanding the interactions between soil moisture and climate warming has implications for the amount of mineralized peatland carbon. This is particularly important in peatland types found in areas expected to experience high rates of climate warming, as an increase in mineralization will accelerate climate change.

Anna Laine, of the University of Eastern Finland, and colleagues tested the impact of climate warming on peatland carbon mineralization under natural and decreased moisture conditions. They tracked photosynthesis, respiration and net CO2 exchange in two Finnish fens subjected to warming and water-level drawdown over two growing seasons. While warming had little effect, dryer conditions were associated with increased photosynthesis and respiration, and together warming and drying decreased CO2 uptake in one site. This suggests that peatland CO2 exchange is more strongly influenced by drying than warming, and that soil moisture may be critical to determining whether fen systems are able to adapt to a changing climate.