Strategies of carbon and nitrogen acquisition by saprotrophic and ectomycorrhizal fungi in Finnish boreal Picea abies-dominated forests

We compared the delta C-13 and delta N-15 of forest material with an extensive sporocarp collection to elucidate the role of litter, wood and soil as fungal carbon and nitrogen sources in Finnish boreal Picea abies-dominated forests. Ectomycorrhizal Hydnum and Cortinarius had higher delta N-15 than other ectomycorrhizal fungi, suggesting use of N-15-enriched, deeper nitrogen. Russula had lower delta N-15 than other ectomycorrhizal fungi and resembled some litter decay genera, suggesting use of litter-derived nitrogen. There was little variation in delta N-15 among other genera of ectomycorrhizal fungi, indicating limited functional diversity in nitrogen use. Saprotrophic Leotia, Gymnopus, Hypholoma, Pholiota, Rhodocollybia and Calocera had delta N-15 values similar to ectomycorrhizal fungi, indicating overlap in use of older nitrogen from soil or roots or use of newly fixed nitrogen. Genera of litter and wood decay fungi varied up to 6 parts per thousand in delta C-13 and 10 parts per thousand in delta N-15, suggesting large differences in carbon and nitrogen sources and processing. Similar delta C-13 between white and brown rot wood decay fungi also suggest that white rot fungi do not use lignin-derived carbon. Together, these delta C-13 and delta N-15 patterns of fungi from Finnish boreal forests enhance our knowledge of fungal functional diversity and indicate broad use of litter, wood and soil resources. (C) 2019 The Author(s). Published by Elsevier Ltd on behalf of British Mycological Society.