Terrestrial and aquatic ecosystems of the boreal to polar regions face tremendous alterations due to a fast changing climate. Besides geophysical and hydrological impacts like vanishing permafrost, coastal erosion and altered runoff, biogeochemical cycles are highly affected by the ongoing changes. Although we are completely aware of the importance of high latitude ecosystems for instance for carbon sequestration, we have a restricted understanding of the biogeochemical processes especially in terrestrial ecosystems. This session aims to bring together scientists working on terrestrial and aquatic ecosystems in the high latitudes, both in Arctic, Antarctic, and Boreal regions, reaching from microbiological functioning and stoichiometric constraints of organic matter turnover and nutrient cycling (e.g. nitrogen, phosphorus) to carbon stabilization and trace gas emissions. We further welcome contributions on interactions between vegetation, microbiota and soils and/or sediments, and the exchange between terrestrial and aquatic systems. Let’s come to together and share results, views and concepts to better understand biogeochemical cycling in boreal and polar regions.