Carbon dioxide and methane emissions from a network of thirty eddy-covariance sites in the Netherlands

Understanding the temporal dynamics and controls on greenhouse gas exchange between terrestrial ecosystems and the atmosphere is critical for advancing process-level understanding and informing national greenhouse gas budgets and inventories. A large portion of soils in the Netherlands are either drained or restored peatlands, where the high carbon/organic matter content is accompanied by large risk of carbon loss to the atmosphere through enhanced soil respiration (drained sites) and/or enhanced methane emissions (rewetted sites). For this reason, increasing attention is being paid to understanding and quantifying the greenhouse gas budgets of both drained and restored peatland sites across the Netherlands. 
 
To both inform national GHG inventories and improve our understanding of site scale process, we present a multi-site analysis of a network of more than thirty eddy-covariance sites in the Netherlands. We discuss the daily, seasonal, and annual variability of carbon dioxide (CO₂) and methane (CH₄) fluxes measured at these sites. These sites include intensively managed grasslands, arable fields, semi-natural pastures, forested peatlands, wetlands and marshes. These sites encompass a wide range of vegetation types, soil characteristics, and water-management practices, with continuous or semi-continuous high-frequency flux datasets extending across multiple years within the last decade.
 
We quantify daily, seasonal, and annual CO₂ and CH₄ fluxes and discuss key biophysical drivers, including soil composition and moisture, vegetation dynamics, groundwater levels, and the impacts of climate anomalies such as temperature and precipitation extremes across varying timescales. We discuss differences between sites and potential impacts of soil characteristics, vegetation, land management, and recent climate anomalies.
 
Our analysis indicates substantial variability in both CO₂ and CH₄ fluxes across sites and seasons. These results highlight the invaluable contributions of both high-resolution flux observations and rigorous data processing methods when disentangling ecosystem controls on gas exchange. These flux observations provide much needed empirical constraints for model evaluation and can facilitate improved representation of peatland and wetland systems in greenhouse gas inventories and process-based models.