Peat deposits store more carbon than trees in forested peatlands of the boreal biome

Peatlands are significant carbon (C) stores, playing a key role in nature-based climate change mitigation. While the effectiveness of non-forested peatlands as C reservoirs is increasingly recognized, the C sequestration function of forested peatlands remains poorly documented, despite their widespread distribution. Here, we evaluate the C sequestration potential of pristine boreal forested peatlands over both recent and millennial timescales. C stock estimates reveal that most of the carbon stored in these ecosystems is found in organic horizons (22.6-66.0 kg m(-2)), whereas tree C mass (2.8-5.7 kg m(-2)) decreases with thickening peat. For the first time, we compare the boreal C storage capacities of peat layers and tree biomass on the same timescale, showing that organic horizons (11.0-12.6 kg m(-2)) can store more carbon than tree aboveground and belowground biomass (2.8-5.7 kg m(-2)) even over a short time period (last 200 years). We also show that forested peatlands have similar recent rates of C accumulation to boreal non-forested peatlands but lower long-term rates, suggesting higher decay and more important peat layer combustion during fire events. Our findings highlight the significance of forested peatlands for C sequestration and suggest that greater consideration should be given to peat C stores in national greenhouse gas inventories and conservation policies.

Automated summary

This study evaluates the carbon sequestration potential of pristine boreal forested peatlands over different timescales, finding that organic horizons have more carbon storage potential than tree biomass. Forested peatlands have similar recent rates of carbon accumulation to non-forested peatlands, but lower long-term rates.