Leaf-level coordination principles propagate to the ecosystem scale.

Optimality principles and patterns in trait coordination have been widely studied and confirmed at the leaf and plant scale. The question now is whether these coordination principles that apply to the leaf and plant scales can be used to approximate ecosystem-scale coordination among communities and ecosystems. Image: Pixabay/ FreePhotosART

Variation in plant traits arises from balancing the costs and benefits of resource-use strategies at the leaf level. The interplay between natural selection and environmental filtering leads to predictable patterns in traits that promote the efficiency of plant processes necessary for growth, survival, and reproduction.

In a recent publication in the journal Nature Communications, researchers explore whether trade-offs and optimality principles in leaf functional traits extend to the ecosystem level. By analyzing a comprehensive dataset from 98 global eddy covariance flux measurement sites and utilizing vegetation data collected in the field and from global plant trait databases, the authors investigate ecosystem-scale analogs to the relationships observed in functional traits.

The leaf economics spectrum, which represents consistent correlations among various leaf traits reflecting a range of plant strategies from conservative to acquisitive, is examined. Additionally, the study explores the global spectrum of plant form and function, which encompasses evolutionary strategies related to plant growth, survival, and reproduction. The researchers also investigate the least-cost hypothesis, which suggests that plants acclimate to minimize carbon costs associated with photosynthesis on a per-leaf-area basis.

The findings of this study indicate that coordination of functional properties is conserved at the ecosystem scale. However, it is important to note that additional processes occur at the ecosystem level compared to the leaf level, emphasizing the significance of scale-emergent properties in understanding and predicting ecosystem behavior. Ulisse Gomarasca from the Max Planck Institute for Biogeochemistry highlights the importance of evaluating ecosystem functional properties for the development of more realistic global dynamic vegetation models, which can reduce uncertainty in climate change projections.

The study provides strong evidence supporting the conservation of the leaf economics spectrum at the ecosystem level. Similarly, the global spectrum of plant form and function and the least-cost hypothesis are observed in whole ecosystems, despite involving secondary mechanisms at the ecosystem scale.

Prof. Josep Penuelas from CSIC-CREAF emphasizes the need for upscaling from leaf or plant to ecosystem-level processes in order to make more accurate predictions about ecosystem responses to global environmental changes. This involves considering whether the coordination observed at the leaf and plant levels is conserved at the ecosystem scale or whether scale-emergent behaviors occur and should be explicitly incorporated into models.

Publication: Gomarasca, U., Migliavacca, M., Kattge, J., Nelson., Niinemets, Ü., Wirth, C., Cescatti, A., Bahn., Nair, R., Acosta, A., Arain, A., Beloiu, M., Black, T., Bruun, H.H., Bucher, F., Buchmann, N., Carrara, A., Byun, C., Conte, A., da Silva, A., Duveiller, G., Fares, S., Ibrom, A., Knohl, A., Komac, B., Limousin, J-M., Lusk, C., Mahecha, M., Martini, D., Minden, V., Montagnani, L., Mori, A., Onoda, Y., Penuelas, J., Poschlod, P., Powell, T., Reich, P., Šigut, L., van Bodegom, P., Walther, S., Wohlfahrt, G., Wright, I., Reichstein, M. 2023. Leaf-level coordination principles propagate to the ecosystem scale. Nature Communications 14:3948. Doi: 10.1038/s41467-023-39572-5.