Interspecific temporal and spatial differences in the acquisition of litter‐derived nitrogen by ectomycorrhizal fungal assemblages

Summary The spatiotemporal dynamics of, and interspecific differences in, the acquisition of litter‐derived nitrogen ( N ) by natural assemblages of ectomycorrhizal root tips are poorly understood. Small cylindrical mesh bags containing 15 N ‐labelled beech ( F agus sylvatica ) leaf litter that permit hyphal but not root ingrowth were inserted vertically into the top soil layer of an old‐growth beech forest. The lateral transfer of 15 N into the circumjacent soil, roots, microbes and ectomycorrhizas was measured during an 18‐month exposure period. Ectomycorrhial fungi ( EMF ) showed large interspecific variation in the temporal pattern and extent of 15 N accumulation. Initially, when N was mainly available from the leachate, microbes were more efficient at N immobilization than the majority of EMF , but distinct fungal species also showed significant 15 N accumulation. During later phases, the enrichment of 15 N in T omentella badia was higher than in microbes and other EMF species. Roots and soil accumulated 15 N with a large delay compared with microbes and EMF . Because approximately half of the studied fungal species had direct access to N from leaf litter and the remainder to N from leached compounds, we suggest that EMF diversity facilitates the N utilization of the host by capturing N originating from early‐released solutes and late degradation products from a recalcitrant source.