Biodiversity and Ecosystem Multifunctionality: Lesson from drylands

Functional traits are often invoked to explain species coexistence and ecosystem functioning. However, the hypothesis that trait differences determine the ability of ecosystems to maintain multiple functions simultaneously (multifunctionality) remains largely untested at a global scale. In a survey of 124 dryland plant communities, we found a unique scaling relationship between trait diversity of specific leaf area and maximum plant height and multifunctionality (productivity and surrogates of carbon, nitrogen and phosphorus cycling). Across a variety of species pools and environmental conditions, trait diversity within communities was strikingly high and maximized multifunctionality. Trait diversity had a much stronger impact on multifunctionality than other multifunctionality drivers (e.g. species richness, aridity). We uncovered a general scaling relationship that quantifies how much plant diversity is required to maximize multifunctionality in global drylands.