Local loss and spatial homogenization of plant diversity reduce ecosystem multifunctionality

Abstract

Biodiversity is declining in many local communities while also becoming increasingly homogenized across space. Experimentsshow that local plant species loss reduces ecosystem functioning and services, but the role of spatial homogenization of communitycomposition and the potential interaction between diversity at different scales in maintaining ecosystem functioningremains unclear, especially when many functions are considered (ecosystem multifunctionality). We present an analysis ofeight ecosystem functions measured in 65 grasslands worldwide. We find that more diverse grasslands?those with both species-rich local communities (α-diversity) and large compositional differences among localities (β-diversity)?had higher levelsof multifunctionality. Moreover, α- and β-diversity synergistically affected multifunctionality, with higher levels of diversity at one scale amplifying the contribution to ecological functions at the other scale. The identity of species influencing ecosystem functioning differed among functions and across local communities, explaining why more diverse grasslands maintained greater functionality when more functions and localities were considered. These results were robust to variation in environmental drivers. Our findings reveal that plant diversity, at both local and landscape scales, contributes to the maintenance of multiple ecosystem services provided by grasslands. Preserving ecosystem functioning therefore requires conservation of biodiversity both within and among ecological communities.