No effect of long-term soil warming on diffusive soil inorganic and organic nitrogen fluxes in a temperate forest soil

Climate warming affects nitrogen (N) cycling in forest soils, but implications for plant available N have remained unclear. We estimated in situ diffusive fluxes of amino acids and inorganic N in a temperate forest soil after 14 years of soil warming. Results from four sampling campaigns (n = 1152 microdialysis samples) during the growing season showed no effect of warming on diffusive N fluxes. Diffusive NH4+ fluxes increased from spring towards autumn while NO3− fluxes followed an opposite trend. Overall, the proportion of amino acids in the total diffusive N flux was low (13–30%) in this carbonate soil compared to other temperate and boreal forest soils.