Wide geographical and ecological distribution of nitrogen and carbon gains from fungi in pyroloids and monotropoids (Ericaceae) and in orchids


Author for correspondence:Gerhard Gebauer Tel: +49 921552060 Fax: +49 921552564 Email: gerhard.gebauer@uni-bayreuth.de


  • •  Stable isotope abundance analyses recently revealed that some European green orchids and pyroloids (Ericaceae) are partially myco-heterotrophic, exploiting mycorrhizal fungi for organic carbon and nitrogen. Here we investigate related species to assess their nutritional mode across various forest and climate types in Germany and California.
  • •  C- and N-isotope signatures of five green pyroloids, three green orchids and several obligate myco-heterotrophic species (including the putatively fully myco-heterotrophic Pyrola aphylla) were analysed to quantify the green plants’ nutrient gain from their fungal partners and to investigate the constancy of enrichment in 13C and 15N of fully myco-heterotrophic plants from diverse taxa and locations relative to neighbouring autotrophic plants.
  • •  All green pyroloid and one orchid species showed significant 15N enrichment, confirming incorporation of fungi-derived N compounds while heterotrophic C gain was detected only under low irradiance in Orthilia secunda. Pyrola aphylla had an isotope signature equivalent to those of fully myco-heterotrophic plants.
  • •  It is demonstrated that primarily N gain from mycorrhizal fungi occurred in all taxonomic groups investigated across a wide range of geographical and ecological contexts. The 13C and 15N enrichment of obligate myco-heterotrophic plants relative to accompanying autotrophic plants turned out as a fairly constant parameter.