BayCEER Workshop 2026

08. October 2026

ISOfun - A database for fungal natural abundance of stable isotopes

Franziska E. Zahn¹, Christina Marburger², Finn Zajewski², Andrey G. Zuev³, Erik A. Hobbie⁴, Gerhard Gebauer⁵, Lisa Hülsmann⁶, Johanna Pausch²

¹ Department of Ecology of Fungi, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany. & Naturalis Biodiversity Center, 2332 AA, Leiden, the Netherlands
² Department of Agroecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440, Bayreuth, Germany.
³ Department of Soil Zoology Senkenberg Institute Senckenberg Museum of Natural Sciences, 02826 Görlitz, Germany.
⁴ Earth Systems Research Center, University of New Hampshire, Durham, New Hampshire, 03833, USA.
⁵ BayCEER - Laboratory of Isotope Biogeochemistry, University of Bayreuth, Bayreuth 95440, Germany.
⁶ Ecosystem Analysis and Simulation (EASI) Lab, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany.

P 2 in Posters

The natural abundance of the stable isotopes of carbon and nitrogen (δ¹³C and δ¹⁵N values) has been used to understand the role of fungi in material cycles, as well as fungal physiology and lifestyles. Meta-analyses of large stable isotope composition datasets capture comprehensive ecological trends across broad spatiotemporal scales, yet they continue to face challenges due to data heterogeneity and inconsistent study documentation.

To overcome this hurdle, we developed a global database of natural abundance data for stable isotopes in fungi: ISOfun. This database provides a uniformly structured organisational scheme, integrating ¹³C and ¹⁵N natural abundance measurements with standardised metadata, e.g. on sample location, collection time, fungal traits, nutritional resources, and the sampling environment. Using a systematic literature search following the PRISMA workflow, we compiled data from 60 studies published up to 2026. The resulting dataset comprises 4,039 fungal sample entries spanning sampling years from 1930 to 2022. We present three distinct case studies to illustrate how the ISOfun database can be leveraged to resolve complex ecological questions at different scales and to generate novel hypotheses.

The ISOfun database compiles published data on stable isotope composition, C and N content and C/N ratios of fungi (fruit body, ectomycorrhizal root tips, intraradical hyphae, extraradical hyphae, peloton, spores, mycelium) and offers a structured framework for the future collection of data, supporting a wide range of ecological and mycological research projects.

Keywords: stable isotopes, fungi, carbon, nitrogen, mycorrhiza, waxcaps, saprotrophs