One important pending question in ecology pertains to the understanding of how biodiversity and its various dimensions relate to the environment in different biogeographical contexts. Yet, our knowledge to answer this question remains fragmentary and inconsistent, seriously impeding our capacity to predict how ecological systems respond to changes, be they natural or human-induced, local or global. The overall objective of FUNBIOME is to fill this knowledge gap using a functional approach to plant diversity in the specific case of the response of plants to drought and temperature, two major components of ongoing climatic changes affecting ecosystems. FUNBIOME will combine existing botanical and trait data along environmental gradients in different biogeographical settings across the Mediterranean region, which is both one of the world’s most important extratropical reservoir of plant diversity, and one of the most vulnerable areas of the planet to climate change. By searching for generalizable trait-environment relationships, FUNBIOME will strengthen what is considered as one of the loose foundation stones of trait-based ecology.