Plant species' origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands.
Seabloom EW., Borer ET., Buckley YM., Cleland EE., Davies KF., Firn J., Harpole WS., Hautier Y., Lind EM., MacDougall AS., Orrock JL., Prober SM., Adler PB., Anderson TM., Bakker JD., Biederman LA., Blumenthal DM., Brown CS., Brudvig LA., Cadotte M., Chu C., Cottingham KL., Crawley MJ., Damschen EI., Dantonio CM., DeCrappeo NM., Du G., Fay PA., Frater P., Gruner DS., Hagenah N., Hector A., Hillebrand H., Hofmockel KS., Humphries HC., Jin VL., Kay A., Kirkman KP., Klein JA., Knops JM., La Pierre KJ., Ladwig L., Lambrinos JG., Li Q., Li W., Marushia R., McCulley RL., Melbourne BA., Mitchell CE., Moore JL., Morgan J., Mortensen B., O'Halloran LR., Pyke DA., Risch AC., Sankaran M., Schuetz M., Simonsen A., Smith MD., Stevens CJ., Sullivan L., Wolkovich E., Wragg PD., Wright J., Yang L.
Exotic species dominate many communities; however the functional significance of species' biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in 13 countries, and at a subset of the sites we experimentally tested native and exotic species responses to two fundamental drivers of invasion, mineral nutrient supplies and vertebrate herbivory. Exotic species are six times more likely to dominate communities than native species. Furthermore, while experimental nutrient addition increases the cover and richness of exotic species, nutrients decrease native diversity and cover. Native and exotic species also differ in their response to vertebrate consumer exclusion. These results suggest that species origin has functional significance, and that eutrophication will lead to increased exotic dominance in grasslands.