Benutzer:Martin Moritzi/Artikelentwurf

In international collaboration researchers at the ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL showed that there were huge differences in the tree growth rates – which correlated with the species composition of their fungal communities. Depending on the fungal species composition, there was a threefold variation in the growth rate of the trees, i.e., trees with the "ideal" fungal community grew three times faster than those associated with the "worst" fungal community. This effect was independent of other factors influencing tree growth, such as climate, forest stand characteristics or the nitrogen balance in the soil.^[1]

Analyses of the fungal genes indicate that the difference may actually be due to the different strategies used by the mycorrhizal fungi to acquire nitrogen: it emerged that fungal communities in fast-growing forests have higher proportions of genes for acquiring nitrogen in its inorganic form. In communities linked to slow-growth forests, on the other hand, there are higher proportions of organic N cycling genes, i.e., genes that enable the fungus to use nitrogen that is bound in organic matter such as leaves.^[1]

Some mycorrhizal fungi have conspicuous fruiting bodies and is thus a species that can be recognised "just like that" in woodland. For example, the brittlegill (Russula ochroleuca), which is very common in fast-growing deciduous and coniferous forests is particularly well adapted to the acquisition of inorganic nitrogen. The edible bay bolete (Imleria badia) is widespread in fast-growing coniferous forests. A list of such species could serve as a means of assessing the productivity of forests, based on the frequency of the relevant fungal fruiting bodies observed in the undergrowth simply during a walk through the stand.^[2]

Forests in which particular fungi have been found to be associated with different tree growth rates should be monitored more intensively. The preservation of these forests and the fungal habitats within them is not just about preserving the fungi. The influence of the fungi on the trees helps to protect and promote forest functions such as timber production, or improve protection against natural hazards.^[2] The fungi that are currently associated with the slow growth of trees could become important in the future, because they break down nitrogen in its organic form and then absorb it. ^[3] Because there is far more organic nitrogen in forest soils, they can still supply "their" trees with sufficient nitrogen, even if inorganic nitrogen becomes scarce because of the expected increase in photosynthesis in future. ^[4] That is at least what greenhouse experiments suggest: in experiments using the CO2 concentrations expected by the year 2100, those fungal species that best exploit organic nitrogen are those that best promote the growth of young tree seedlings. ^[2]

1. ↑ ^{a b} Mark A. Anthony, Thomas W. Crowther, Sietse van der Linde, Laura M. Suz, Martin I. Bidartondo, Filipa Cox, ... Colin Averill: Forest tree growth is linked to mycorrhizal fungal composition and function across Europe. In: ISME Journal. Band 16, 2017, S. 1327–1336, doi:10.1038/s41396-021-01159-7 (englisch). 
2. ↑ ^{a b c} Mark A. Anthony, Marco Ferretti, Beat Frey, Arthur Gessler, Marcus Schaub: How different fungal communities influence tree growth. In: waldwissen.net. 25. Juli 2022, abgerufen am 19. Juli 2023. 
3. ↑ Odair Alberton, Thomas W. Kuyper, Antonie Gorissen: Competition for nitrogen between Pinus sylvestris and ectomycorrhizal fungi generates potential for negative feedback under elevated CO₂. In: Plant Soil. Band 296, 2007, S. 159–172, doi:10.1007/s11104-007-9306-5 (englisch). 
4. ↑ César Terrer, Sara Vicca, Benjamin D. Stocker, Bruce A. Hungate, Richard P. Phillips, Peter B. Reich, Adrien C. Finzi, I. Colin Prentice: Ecosystem responses to elevated CO₂ governed by plant–soil interactions and the cost of nitrogen acquisition. In: New Phytologist. Band 217, 2017, S. 507–522, doi:10.1111/nph.14872 (englisch).