Global change drivers such as anthropogenic nutrient inputs
simultaneously alter biodiversity, species composition, and ecosystem
functions such as above ground biomass. These changes are interconnected
by complex feedbacks among extinction, invasion, and shifting relative
abundance. Here, we use a novel temporal application of the Price
equation to separate species richness and biomass change through time
and quantify the functional contributions of species that are lost,
gained, and persist under ambient and experimental nutrient addition in
59 global grasslands. Under ambient conditions, compositional and
biomass turnover was high, but species losses (i.e., local extinctions)
were balanced by gains (i.e. colonization). Under fertilization, there
was biomass loss associated with species loss. Few species were gained
in fertilized conditions over time but those that were, and species that
persisted, contributed to net biomass gains, outweighing biomass loss.
These components of community change are associated with distinct
effects on measures of ecosystem functioning.