Why biodiversity-rich ecosystems perform better

Zooming in on the causes of complementarity in grasslands

Report by Katie Barry, postdoctoral researcher at iDiv and the UL and first author of a new paper in Trends in Ecology and EvolutionLeipzig. “How” biodiversity enhances ecosystem functioning may be just as important as “that” biodiversity enhances ecosystem functioning. Our new review in Trends in Ecology and Evolution highlights how focusing on the consequence of enhanced ecosystem functioning in more diverse ecosystems has caused scientists to overlook the “how” of biodiversity ecosystem functioning relationships. This review also emphasises that understanding how relationships between biodiversity and ecosystem functioning arise changes the implications of biodiversity loss in more diverse systems. Understanding how biodiversity loss will affect ecosystem functioning is one of the major goals of biodiversity-ecosystem functioning experiments. Yet, biodiversity-ecosystem functioning research often focuses on the abstract idea of “complementarity” where species “fit together like puzzle pieces” to enhance ecosystem functioning. Complementarity is used so frequently in this context that it is often conflated with the consequence of better performance in mixture. This false association forces biodiversity-ecosystem functioning research to focus on the consequence of better performance and neglect what causes better performance. In our review, we focus on three potential causes of complementarity that may enhance ecosystem functioning in more biodiverse systems: resource partitioning, abiotic facilitation, and biotic feedbacks. We found that there is evidence that plants partition resources, facilitate each other through changes to abiotic conditions, and are subject to positive and negative biotic feedbacks. However, there is very little evidence directly tying these different causes to enhanced ecosystem functioning in more diverse plant mixtures. Further, we argue that understanding how these different causes may drive enhanced ecosystem functioning is important. This is because they have different ecological consequences when species are lost, vary across ecological contexts, and may combine with each other. Finally, we predict that – when causes combine – biodiversity may be even more important for supporting ecosystem functioning. 
Kathryn E. Barry

Original paper:

(iDiv scientists in bold) Barry, K.E., Mommer, L., van Ruijven, J., Wirth, C., Wright, A.J., Bai, Y., Connolly, J., De Deyn, G.B., de Kroon, H., Isbell, F., Milcu, A., Roscher, C., Scherer-Lorenzen, M., Schmid, B., & Weigelt, A. (2018). The future of complementarity: Disentangling causes from consequences. Trends in Ecology and Evolution. https://doi.org/10.1016/j.tree.2018.10.013

Contact:

Dr Kathryn E. Barry
Flexpool postdoc
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
Community Assembly and the Functioning of Ecosystems
Systematic Botany and Functional Biodiversity
Leipzig University
Mail: kathryn.barry@idiv.de

Further Information:

The Jena Experiment:
http://www.the-jena-experiment.de/