Ectomycorrhizal hydrophobicity influences ectomycorrhizal C dynamics, N dynamics, and fruiting patterns in N addition experiments under pine

Abstract

Abstract Background Fungal morphology such as the hydrophobicity of ectomycorrhizae may correspond to functional attributes including enzymatic capabilities, carbon (C) demand from host plants, temporal patterns of fruiting, C sequestration, and nitrogen (N) sequestration. Here, we assessed how ectomycorrhizal hydrophobicity influenced the timing of C dynamics and fungal processing of C and N, as integrated by fruiting patterns, δ13C, δ15N, and loge C/N of ectomycorrhizal sporocarps. Methods We linked δ13C, δ15N, loge C/N, and temporal fruiting patterns of ectomycorrhizal sporocarps and soils across seven N fertilization treatments in two Swedish Pinus sylvestris L. forests to ectomycorrhizal hydrophobicity and daily gross primary production. Results Gross primary production of seven and 6–9 days prior to collection correlated positively with sporocarp δ13C and loge C/N, respectively, reflecting transit times of peak delivery of plant-derived carbohydrates to sporocarp formation. Hydrophobic taxa fruited 10 days later than hydrophilic taxa, suggesting greater C demands for hydrophobic taxa. Taxa with hydrophobic ectomycorrhizae had lower δ13C, higher δ15N, and higher loge C/N (less protein) than taxa with hydrophilic ectomycorrhizae. Conclusions Long C accumulation times and high sequestration (hydrophobic taxa) versus low sequestration (hydrophilic taxa) of 13C-enriched carbohydrates and 15N-depleted chitin in mycelia could account for the late fruiting, 13C depletion, and 15N enrichment of hydrophobic sporocarps. We concluded that sporocarp production and hydrophobicity integrated functional information about the extent of belowground hyphal development and the C accumulation times of C transfers from host Pinus.