Data from: Plant functional diversity modulates global environmental change effects on grassland productivity

1. Although much research has explored changes in ecosystem functions
associated with global environmental changes, the mechanistic pathways
behind the observed changes remain poorly understood. 2. Using an 11-year
experiment that increased growing season precipitation and nitrogen
deposition in a temperate steppe, we explored the relative importance of
direct and indirect environmental change effects on plant primary
productivity. 3. We show that increases in water and nitrogen availability
influenced plant productivity via both direct and indirect pathways. While
both treatments stimulated plant productivity, changes in plant
productivity cannot be explained by observed changes in species or
phylogenetic diversity. Instead, the indirect effects of water and
nitrogen addition were through their positive effects on plant functional
diversity. Importantly, while the increase in one component of functional
diversity (community-level weighted mean of plant stature) resulted in
increased productivity, the increase in another component of functional
diversity (functional dispersion) resulted in decreased productivity. 4.
Synthesis. Our study provides the first evidence for the opposite effects
of community weighted means and functional dispersion of plant functional
traits on grassland productivity, and highlights the importance of both
traits of dominant species and trait distribution among species in
modulating the effects of global changes on ecosystem functions.