Heterotrophic soil respiration in three forestry-drained boreal peatlands dominated by Downy birch (Betula pubescens Ehrh.)

Boreal peatlands contain a significant terrestrial carbon storage. Many of the boreal mire sites support tree growth naturally, and tree stands largely affect their carbon dynamics controlling the decomposition and new carbon inputs. Most research has focused on the conifer stands, with limited attention given to carbon emissions from peatland sites dominated by stands of deciduous tree species and how the emissions change along stand succession. We studied heterotrophic soil respiration (CO2) using site-specific temperature and water table interaction models and simulations at half-hourly intervals over two growing seasons (May–September 2021–2022) in three downy birches (Betula pubescens Ehrh.)-dominated drained nutrient-rich peatland sites in Finland. The stand represented three developmental classes: young stand (stand age 10 years), middle-aged stand (50 years), and mature stand (80 years). Instantaneous CO2 fluxes ranged from 0.09 to 1.37 g CO2 m−2 h−1, and mean cumulative fluxes ranged 11.6–30.3 g m−2 d−1. For the summer period, the cumulative fluxes showed to decrease along the stand age being highest (2927 g CO2 m−2) in young stand, and lowest (1113 g CO2 m−2) in mature stand. These results highlight how stand development influences soil carbon emissions, with key implications for peatland management and climate mitigation.