Temporal stability of grassland metacommunities is regulated more by community functional traits than species diversity

Temporal stability in aboveground net primary productivity (ANPP) is influenced by several attributes of plant communities. Identifying the primary regulators of stability and their roles across spatial scales is of both practical and theoretical importance. We assessed effects of species diversity (local or alpha diversity and species dissimilarity between local communities) together with spatial differences in two community functional attributes (mean aboveground biomass and community leaf dry matter content, LDMC) on temporal stability in spring ANPP of restored grassland. Biomass, community LDMC, and species dissimilarity were derived from remote measurements of canopy reflectance of grassland on two soil types. Results demonstrated that productivity at the larger spatial scale of the metacommunity (communities connected by dispersal) was stabilized more by spatial differences in community functional traits than by diversity or community differences in diversity. Spatial differences in community biomass and LDMC stabilized metacommunity productivity by increasing differences in the productivity responses of spatially distinct communities to interannual variation in precipitation, but de-stabilized ANPP on one soil type by reducing the temporal stability of local communities. Our results demonstrate the utility of remote sensing for quantifying community attributes useful to assess or predict temporal stability of grassland ANPP. We conclude that temporal stability in productivity depended largely on community differences in functional attributes that couple plant growth to changes in resource availability.