Data for mycorrhizal C/N ratio determines plant-derived carbon and nitrogen allocation to symbiosis

Nutrient cycling in temperate forests is driven by carbon allocation of
trees to soil via ectomycorrhizas (EM). The sink activities of different
fungal taxa for host resources are unknown. Aboveground
dual labeling of young beech with 15N and 13C was used to trace
resource transport to ectomycorrhizal root tips. Isotope enrichment in EM
correlated with that in the corresponding EM-attached lateral root,
supporting that EM drive taxon-specific N- and C-fluxes. The
enrichments with 13C and 15N in EM increased with decreasing C/N
ratio of the symbiotic association.  Abundances of EM species
were positively correlated with 13C enrichment, demonstrating higher
fitness of stronger than of less C-demanding symbioses. Overall, our
results imply that differences among the resource traits of EM species
regulate the supply of the symbioses with host-derived C and N. Here we
provide the data sets containing information on the identities of fungal
species colonizing roots tips of European beech and for N, C, 15N and 13C
contents in bark, coarse roots, fine roots, very fine lateral roots,
ectomycorrhizal species and rhizosphere soil and for biomass of the
different compartments. The data were collected 5 and 20 days after
labelling.