Experimental winter icing and summer warming effects on carbon fluxes and litter decomposition in mesic tundra, Adventdalen, Svalbard (2016-2022)

These datasets contain measurements from a multi-year field experiment designed to assess the effects of winter icing and summer warming on carbon cycling in mesic tundra in Adventdalen, Svalbard (78°10′N [degrees North], 16°05′E [degrees East]). The experiment followed a full-factorial design with four treatments (control, icing, warming, and icing plus warming) applied across replicated plots from 2016 to 2022. The datasets include (i) ecosystem carbon dioxide fluxes (gross ecosystem production, ecosystem respiration, and net ecosystem exchange) measured during the 2018 growing season, (ii) plant litter decomposition data derived from standardized tea bag index assays across winter, summer, and annual incubations between 2019 and 2022, and (iii) associated vegetation and environmental variables, including normalized difference vegetation index, soil moisture, and moss-mat and soil temperatures. These data enable quantification of both rapid (flux-based) and slower (decomposition-based) components of carbon cycling and provide a basis for evaluating the individual and interactive effects of winter rain-on-snow-induced icing and summer warming on Arctic tundra ecosystem functioning