A global dataset of key traits for plant belowground functioning.

Belowground functional diversity is relevant to numerous ecosystem functions and to ecosystem resilience under global change, yet quantitative information on belowground plant traits is disparate and poorly integrated across fields of research. So far, belowground plant traits have been studied in three disparate research domains: (i) fine root traits in the context of belowground resource economics and symbioses; (ii) maximum rooting depth and lateral extent of the root system in the context of overall plant allometry and resource uptake; (iii) clonal organs and bud banks with a focus on plant and community resilience. However, there remains a major disconnection among these three fields of research. A prerequisite for linking them together is the creation of a comprehensive, curated, open-access dataset available for comprehensive analyses. Here, we compiled and harmonised such a trait dataset for 10,453 vascular plant species and 19 belowground plant traits, which we named UNDERPLOT. Based on these data, we defined two integrative indices, a Belowground Persistence Type (BPT) and a Clonal Spread Index (CSI), which are suitable trait-based indicators for predicting resistance and resilience of communities to disturbance. Further applications will increase our knowledge of the dimensionality of the belowground trait space, adding new insights into trait-environment relationships, vegetation responses to climate change and disturbance, as well as a deeper understanding of evolutionary first principles.