Plant species' origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands.

Eric W Seabloom,Brent Mortensen,Yvonne M Buckley,Guozhen Du,Helmut Hillebrand,David A Pyke,Kimberly J La Pierre,Hope C Humphries,Chengjin Chu,Peter D Wragg,Carly J Stevens,John L Orrock,Peter B Adler,Cynthia S Brown,W Stanley Harpole,Andrew S Macdougall,Joslin L Moore,Dana M Blumenthal,Melinda D Smith,Yann Hautier,Martin Schuetz,Lori A Biederman,Jonathan D Bakker,Nicole M Decrappeo,Virginia L Jin,Johannes M H Knops,Qi Li,Brett A Melbourne,Anita C Risch,Jennifer Firn,Wei Li,Kendi F Davies,Daniel S Gruner,Michael J Crawley,Elizabeth T Borer,Mahesh Sankaran,Suzanne M Prober,Ellen I Damschen,Philip A Fay,Eric M Lind,Kathryn L Cottingham,Rebecca L Mcculley,John G Lambrinos,Nicole Hagenah,Lars A Brudvig,Charles E Mitchell,Elsa E Cleland,John Morgan,Adam Kay,Julia A Klein,T Michael Anderson,Andy Héctor ,Marc W Cadotte ,Elizabeth M Wolkovich ,Laura M Ladwig ,Kevin Kirkman ,Kirsten Hofmockel ,Paul N Frater ,Lauren L Sullivan ,Justin P Wright ,Anna K Simonsen ,Carla M D’antonio ,Lydia R O’halloran ,Robin G Marushia ,Louie H Yang

doi:10.1038/ncomms8710

Abstract

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.

Highlights

Exotic species dominate many communities; the functional significance of species’ biogeographic origin remains highly contentious
If exotic species differ from native species in their response to anthropogenic change, species origin is clearly relevant for management
While we found that both exotic and native species can dominate a local ecosystem, exotic species were more likely to dominate grasslands globally compared with their native counterparts

Summary

Introduction

Exotic species dominate many communities; the functional significance of species’ biogeographic origin remains highly contentious. There have been no globally replicated studies that use consistent methods to measure native and exotic abundance in response to experimental perturbations, and, in spite of ongoing debate in the literature[8,9], we cannot currently resolve questions about the relevance of species origin. We address this knowledge gap by evaluating whether native and exotic species differ in their abundance distributions and responses to nutrients and grazing by conducting a standardized experiment within grassland ecosystems in 13 countries on four continents (Supplementary Fig. 1 and Supplementary Table 1). Grasslands are well suited for studying biological invasions, because many are highly invaded[21,24], and changes in human land use, altered nutrient supplies, and altered consumer pressure have been suggested as drivers of invasion in the world’s grasslands[21,25,30,31] and in ecosystems generally[22,32]

Methods

Results

Conclusion