Estimation of greenhouse gas emission mitigation and atmospheric carbon dioxide sequestration in restored peatlands (raised bogs) in Latvia

Peatlands play an important role in global climate regulation and carbon (C) cycling. To evaluate the potential effect of peatland restoration on greenhouse gas (GHG) emission mitigation, and preservation of peat C stock or enhancement of atmospheric carbon dioxide (CO₂) sequestration, we used a manual chamber method to measure soil heterotrophic respiration CO₂ emissions (R_het) and ecosystem GHG emissions. Ecosystem emission measurements included methane (CH₄), nitrous oxide (N₂O) emissions and forest floor CO₂ emissions (R_floor) in forested peatlands or ecosystem CO₂ emissions (R_eco) in peatlands without tree cover. Measurements of R_eco and R_floor were conducted using chambers that included all vegetation present in the ecosystem or ground vegetation, respectively. R_het measurements were performed after the removal of ground vegetation and litter layer and trenching of the roots. In addition to GHG emission measurements, C input into the soil with vegetation litter was estimated, and environmental variables (including soil temperature and moisture, groundwater level, water chemistry and others) that potentially can affect the magnitude of GHG emissions were monitored. The monitoring was initiated in 2023 and continued in 2024 at seven study sites located in raised bogs within the hemiboreal vegetation zone of Europe, specifically in Latvia. Study sites included different habitats of pristine peatlands, restored peatlands through rewetting, and areas in both strong and weak drainage impact zones where the development of woody vegetation characteristic of the forest ecosystem has occurred. Preliminary results of GHG emission measurements show that the annualized monthly mean ecosystem gross GHG emissions, expressed in CO₂ equivalents (excluding C sequestration by vegetation), ranged from 9.7 to 45.9 t CO₂ eq. ha⁻¹ year⁻¹ in degraded (drained) peatlands, while in restored (including rewetted) peatland GHG emissions ranged from 11.0 to 25.3 t CO₂ eq. ha⁻¹ year⁻¹.

Acknowledgements: The research was conducted within the scope of the European Commission LIFE Climate Action Programme Project “Peatland restoration for greenhouse gas emission reduction and carbon sequestration in the Baltic Sea region” (LIFE21 - CCM - LV - LIFE PeatCarbon, Project number: 101074396).