Springtime melting and DOC leaching from northern fen – how changing snow conditions impact spatial hydrological processes in peatlands

Northern peatlands have a key role in global carbon exchange but at the same time they are expected to face severe climate change driven alterations. A substantial fraction of the peatland carbon exchange occurs through lateral flux of dissolved organic carbon (DOC), and due to the strong seasonality DOC dynamics in northern environments are prone to ongoing hydrologic and climatic changes. Changes in snow accumulation and melt can alter DOC leaching patterns and thus a detailed understanding of the processes occurring during the spring melt period is required. Although recently more attention has been drawn to exploring the high-resolution temporal dynamics in lateral carbon flux, spatial processes in peatland DOC transport are still not adequately documented and understood. In addition, further effort is needed to combine high-resolution spatial and temporal data. We aim to address this gap by using high-resolution unmanned aircraft system (UAS) monitoring of snow cover and melt during the peak melt period with daily UAS mapping in spring 2024. The spatial mapping is combined with high-frequency in-situ DOC and hydrological monitoring in Puukkosuo fen located next to Oulanka Research Station, northeastern Finland. Our installations include a stream gauging station in the peatland outlet with continuous UV-Vis spectroscopy based water quality measurements (DOC, nitrate, turbidity) along with pH and water isotope monitoring. We also monitor other key hydrological parameters in groundwater wells. The objective was to document spatial variations in snow cover melt and hydrological activation, link these spatial processes to DOC export, and identify the key spatiotemporal processes occurring during the spring melt period. With this approach, we work towards a better understanding of peatland ecohydrology, develop and test methods to use novel monitoring techniques for peatland research and management, and provide framework for predictions of peatland carbon dynamics in response to changing snow regimes.