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6969580 
Journal Article 
What are waxcaps (genus Hygrocybe s. l.) looking for on nutrient poor grassland? 
Ruthsatz, B; , 
2018 
1 
Tuexenia
ISSN: 0722-494X 
FLORISTISCH-SOZIOLOGISCHEN ARBEITSGEMEINSCHAFT E V 
GOETTINGEN 
235-250 
WOS:000447356800013 
It is still uncertain which nutrition strategy waxcap fungi (Hygrocybe s. l.: Hygrocybe, Cuphophyllus und Gliophorus) are pursuing on nutrient-poor grasslands. Where do they get nitrogen and carbon from, especially since they are sensitive to mineral N-fertilizer? Are they able to extract it from soil organic matter in a saprotrophic manner or are they biotrophic, depending on plants? Waxcap species have been studied in western Rhineland-Palatinate (Germany) on over 100 grasslands from 2010 until 2017. In 2014 and 2015, fruit bodies of 12 frequent waxcap species have been collected and analysed regarding their content of nutrient elements (C, N, P) and stable isotopes delta N-15 parts per thousand and delta C-13 parts per thousand. The results were compared with the elements in the leaves of two plant species (Plantago lanceolata, Sanguisorba minor) collected from the same grasslands in 2016.The contents varied strongly between the twelve species but also between the samples of each species. The fungi contained twice as much N and P than the forbs. The delta N-15 parts per thousand values of the fungi were positive and showed great differences between the species (means: 8.2 to 13.7%0), while the plant leaves showed predominantly negative values. From 47 grasslands, the mean value of Plantago was -2.8 and of Sanguisorba -1.9. With -29 parts per thousand the mean values of delta C-13 parts per thousand in fungi and plants were nearly the same.The great similarity between the delta C-13 parts per thousand values of fungi and plants allows the assumption that the fungi get C from assimilates of the plants. However, a direct contact between fungi mycelium and plant roots has only been observed for Plantago and C. virgineus. The N source of the fungi might be the organic matter in the soils of nutrient-poor grasslands, which the fungi might be able to decompose in a saprotrophic manner. The delta N-15 values of the upper soil layers in similar grasslands vary between +3 and +8 parts per thousand, which corresponds to the range in the waxcaps in this study.Significant correlations between N, P, C-13 and N-15 in plants and fungi indicate possible biotrophic exchange of substances. Positive correlations for P between C. virgineus and C. pratensis with those of Plantago or Sanguisorba may be a proof for a transfer of substances from fungi to plants. Correlations between delta N-15 of Plantago and the waxcaps C. virgineus and C. fornicatus as well as between Sanguisorba and H. quieta, G. irrigatus and H. intermedia can be seen as a transfer of N compounds from fungi to plants.