Coarse particulate organic matter is the primary source of mineral N in the topsoil of three beech forests

► Litter-released 15N was mainly found in the coarse POM fractions >200 μm. ► Mineralization of litter 15N is two to four-fold higher than mineralization of the average soil N. ► Highest rates of 15N mineralization happened in the soil with the lowest N content.