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. Keywords: Soil warming; Microdialysis; Amino acids; Diffusive N fluxes; Temperate forest, Nitrogen availability
