Drivers on Carbon Accumulation Vary Along the Hydrological Gradient of a Subarctic Patterned Peatland

Peatlands are important climate change mitigation agents as they store large amounts of carbon (C). Yet, their C sink capacity is vulnerable to environmental changes, which is however uncertain in a changing climate. Here, we examined potential habitat-specific C accumulation drivers over the past ∼1,000 years, using replicate peat records sampled from dry strings and wetter lawns of a subarctic patterned peatland. We found that at both habitats water-table depth impacted the plant functional types and/or peat properties, but they impacted the C accumulation significantly only at lawns. Specifically, the plant functional type and water-table depth had stronger controls on C accumulation than peat properties. Our data suggest that drying-induced C accumulation decrease maybe compensated by Sphagnum expansion in wetter areas. This implies that peatland C accumulation at different habitats is likely to respond to climate changes in varying ways. Thus, quantification of the climatic links to habitat-specific succession and C processes is needed before peatland C sink capacity can be predicted.