Ecological communities are experiencing unprecedented change as a result of anthropogenic pressures such as climate change, land use change and invasive species. Impacts of these pressures are well documented at a global scale by an accelerating global extinction rate, but at the local scale species diversity tells a different story. Recent syntheses of local trends in biodiversity over time have found no net change in local species diversity despite ongoing turnover and evidence of significant shifts in community composition underlying consistent species richness. While communities are clearly changing, our most common species-based approaches do not fully capture the nature of that change.
Functional diversity offers a potentially powerful alternative for detecting and describing community change by providing a mechanistic link between the organisms in a system and the processes they perform. By describing the functional trait space rather than species, functional diversity metrics capture the disproportionate impact of losses or gains of functionally unique species. Functional diversity metrics are therefore particularly well-suited for assessing the implications of community shifts in the full range of species change scenarios.
Despite its promise, broad-scale assessments of temporal change in functional diversity have been severely limited by availability of functional trait data and the computational tools to assess them. Here, we perform the first multi-taxa, multi-system assessment of functional diversity change through time. Along with assessments of functional shifts relative to species change, we discuss the tools underpinning the significant synthesis dimension of this study.
