Text by: Carlos Carmona and Riin Tamme
A study about how fine root traits fit in plant form and function led by EcolChange members is published in this week’s issue of Nature magazine. The study is also featured on the cover page (illustration by Luís Gustavo Barretto Rodrigues).
Functional traits provide information about how plants will respond to changes in environmental conditions, such as global warming, and how they affect the functioning of ecosystems. However, plants have many different traits (e.g., height, seed size, leaf nutrient contents or root diameter), and understanding which ones are coordinated and which ones provide additional information is complicated. So far, research has mainly focused on aboveground plant organs and traits, while the characteristics of roots have not been properly considered.
Together with researchers from Argentina and Canada we took on the challenge to compile data on aboveground organs and fine roots. We explored global relationships between the aboveground functional traits of 39 260 plant species and fine-root traits of 2050 species. We found that the aboveground and fine-root traits of species are fundamentally decoupled so that the aboveground functional strategy of a plant does not reveal much about its fine-root strategy, and vice versa. We also compared the aboveground and fine-root traits of different groups (e.g. herbaceous or woody plants, different families) and found that they mostly differentiate in their aboveground traits, but they tend to be much more similar in terms of their fine roots. Understanding the covariation of aboveground and belowground traits will help to explain how evolution has shaped whole plant strategies to cope with biotic and abiotic environments.
Citation: Carmona, C.P., Bueno, C.G., Toussaint, A., Träger, S., Díaz, S., Moora, M., Munson, A.D., Pärtel, M., Zobel, M., & Tamme, R. 2021. Fine-root traits in the global spectrum of plant form and function. Nature 597: 683–687. (link to paper, free to read)
Plant traits determine how individual plants cope with heterogeneous environments. Despite large variability in individual traits, trait coordination and trade-offs result in some trait combinations being much more widespread than others, as revealed in the global spectrum of plant form and function (GSPFF) and the root economics space (RES) for aboveground and fine-root traits, respectively. Here we combine the traits that define both functional spaces. Our analysis confirms the major trends of the GSPFF and shows that the RES captures additional information. The four dimensions needed to explain the non-redundant information in the dataset can be summarized in an aboveground and a fine-root plane, corresponding to the GSPFF and the RES, respectively. Both planes display high levels of species aggregation, but the differentiation among growth forms, families and biomes is lower on the fine-root plane, which does not include any size-related trait, than on the aboveground plane. As a result, many species with similar fine-root syndromes display contrasting aboveground traits. This highlights the importance of including belowground organs to the GSPFF when exploring the interplay between different natural selection pressures and whole-plant trait integration.