Unterirdische Pflanzenmerkmale und ihr Einfluss auf die Biodiversität und Ökosystemfunktionen
Zusammenfassung der Projektergebnisse
Many of the processes that determine the distributions of plant species and the functioning of ecosystems take place belowground. However, while many studies have focussed on aboveground functional traits of plants, belowground functional traits have been largely ignored. Therefore, we had proposed to assess root functional traits and fungal endophyte infection for the approximately 350 flowering plant species that occur in the 150 grassland experimental plots of the Biodiversity Exploratories. We managed to get seed material for 311 species, and although not all of them germinated, we managed to measure for most of them root-morphological traits, rooting depth, nitrogen-uptake, root anatomy and mycorrhization. These data, measured in four different experiments, were then combined with other data to address our main research questions. First, we tested how the different belowground traits relate to success of the species at different spatial scales, ranging from abundance in the grassland plots of the Biodiversity Exploratories to global naturalization success. Low root tissue density characterized common species at every scale, whereas other traits showed directional changes depending on the scale. We also found that many of the effects had significant non-linear effects, in most cases with the highest commonness-metric value at intermediate trait values. Most importantly, our study showed that within grasslands, belowground traits are at least as important as aboveground traits for species commonness. Second, we tested whether the two dimensions of the root economic space (i.e. the collaboration and conservation gradients), as recently established using species mean values by Bergmann et al. (2020), also applies at the level of communities. Using the belowground traits that we measured, we calculated for each of the 150 grassland sites community weighted means of each trait, and used PCA to assess whether the collaboration and conservation gradients correspond to the first two axes. We found that this was largely the case. Then we related those axes to land-use and other environmental variables. ‘Outsourcing’ communities were more likely to be deep-rooting, and associated with low moisture and sand content top soils, high pH, high C:N and low delta-N-15. ‘Slow’ communities had large bud-banks and were associated with low land-use intensity, high top soil pH, low nitrate and high ammonium. Our results suggest that multiple components of soil physico-chemical composition exert contrasting pressures on root trait values. Finally, we also used our data to test whether there is a trade-off between belowground absorptive surface maximization by roots and mycorrhizal partners. Indeed, we found a phylogenetically conserved trade-off between plant investment into root hairs and the mycorrhizal colonization rate. A similar trade-off between root hair incidence and mycorrhizal colonization also occurred within species. Overall, the results of our project show that belowground plant traits are related to the success of plants at different spatial scales, that belowground traits are associated with certain environmental variables, and might due to trade-offs constitute different belowground plant strategies.
Projektbezogene Publikationen (Auswahl)
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(2020). Global root traits (GRooT) database. Global Ecology and Biogeography
Guerrero-Ramirez, N. et al.
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(2020). The fungal collaboration gradient dominates the root economics space in plants. Science Advances, 6(27), 1–9
Bergmann, J., Weigelt, A., Van der Plas, F., Laughlin, D. C., Kuyper, T. W., Guerrero-Ramirez, N., Valverde-Barrantes, O. J., Bruelheide, H., Freschet, G. T., Iversen, C. M., Kattge, J., McCormack, M. L., Meier, I. C., Rillig, M. C., Roumet, C., Semchenko, M., Sweeney, C. J., Van Ruijven, J., York, L. M., & Mommer, L.
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(2021) Below- and aboveground traits explain local abundance, and regional, continental and global occurrence frequencies of grassland plants. Oikos 130:110-120
Lachaise T, Bergmann J, Rillig MC & van Kleunen M
