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

Authors: SEABLOOM, ERIC - University Of Minnesota; BORER, ELIZABETH - University Of Minnesota; BUCKLEY, YVONNE - University Of Queensland; CLELAND, W. - University Of California; DAVIES, KENDI - University Of Colorado; FIRN, JENNIFER - Queensland University Of Technology; HARPOLE, STANLEY - Iowa State University; HAUTIER, YANN - University Of Zurich; LIND, ERIC - University Of Minnesota; MACDOUGLALL, ANDREW - University Of Guelph; ORROCK, JOHN - University Of Wisconsin; PROBER, SUZANNE - Commonwealth Scientific And Industrial Research Organisation (CSIRO); ADLER, PETER - Utah State University; ANDERSON, T. - Wake Forest University; BAKKER, JONATHAN - University Of Washington; BIEDERMAN, LORI - Iowa State University; Blumenthal, Dana; BROWN, CYNTHIA - Colorado State University; BRUDVIG, LARS - Michigan State University; CHU, CHENGJIN - Lanzhou University; CRAWLEY, MICHAEL - Imperial College; DAMSCHEN, ELLEN - University Of Wisconsin; DANTONIO, CARLA - University Of California; DECRAPPEO, NICOLE - Us Geological Survey (USGS); DU, GUOZHEN - Lanzhou University; Fay, Philip; FRATER, PAUL - Iowa State University; GRUNER, DANIEL - University Of Maryland; HAGENAH, NICOLE - University Of Kwazulu-Natal; HECTOR, ANDY - University Of Zurich; HILLEBRAND, HELMUT - Carl von Ossietzky University Of Oldenburg; HOFMOCKEL, KIRSTEN - Iowa State University; HUMPHRIES, HOPE - University Of Colorado; Jin, Virginia; KAY, ADAM - St Thomas University; KIRKMAN, KEVIN - University Of Kwazulu-Natal; KLEIN, JULIA - Colorado State University; KNOPS, JOHANNES - University Of Nebraska; LA PIERRE, KIMBERLY - Yale University; LAMBRINOS, JOHN - Oregon State University; LEAKEY, ANDREW - University Of Illinois; LI, QI - Chinese Academy Of Sciences; LI, WEI - Yunnan University; MCCULLEY, REBECCA - University Of Kentucky; MELBOURNE, BRETT - University Of Colorado; MITCHELL, CHARLES - University Of North Carolina; MOORE, JOSLIN - University Of Melbourne; MORGAN, JOHN - La Trobe University; MORTENSEN, BRENT - Iowa State University; PYKE, DAVID - Us Geological Survey (USGS); RISCH, ANITA - Swiss Federal Institute; SCHUETZ, MARTIN - Swiss Federal Institute; SMITH, MELINDA - Yale University; STEVENS, CARLY - Lancaster University; SULLIVAN, LAUREN - Iowa State University; WOLKOVICH, ELIZABETH - University Of California; WRAGG, PETER - University Of Minnesota; WRIGHT, JUSTIN - Duke University; YANG, LOUIE - University Of California

Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2015
Publication Date: 7/15/2015
Publication URL: http://handle.nal.usda.gov/10113/5852147
Citation: Seabloom, E., Borer, E.T., Buckley, Y., Cleland, W.E., Davies, K., Firn, J., Harpole, S., Hautier, Y., Lind, E., MacDougall, A., Orrock, J.L., Prober, S.M., Adler, P., Anderson, T.M., Bakker, J.D., Biederman, L.A., Blumenthal, D.M., Brown, C.S., Brudvig, L.A., Cadotte, M., Chu, C., Cottingham, K.L., Crawley, M.J., Damschen, E.I., Dantonio, C.M., DeCrappeo, N.M., Du, G., Fay, P.A., Frater, P., Gruner, D.S., Hagenah, N., Hector, A., Hillebrand, H., Hofmockel, K.S., Humphries, H.C., Jin, V.L., Kay, A., Kirkman, K.P., Klein, J.A., Knops, J.M., La Pierre, K.J., Ladwig, L., Lambrinos, J.G., Li, Q., Li, W., Marushia, R.,McCulley, R., Melbourne, B., Mitchell, C.E., Moore, J.L., Morgan, J., Mortensen, B., O'Halloran, L.R., Pyke, D.A., Risch, A.C., Sankaran, M., Schuetz, M., Simonsen, A., Smith, M., Stevens, C., Sullivan, L., Wolkovich, E., Wragg, P.D., Wright, J., Yang, L. 2015. Plant species' origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands. Nature Communications. 6(7710):1-8. doi:10.1038/ncomms8710.

Interpretive Summary: Exotic plant species are those which have been transported by human action from their original native geographic range to locations where they are not members of the native plant community. Exotic species have expanded in their introduced range and crowded-out many native plant species. It remains unclear why exotic species out-compete native species. This paper provides a unique and important perspective on whether species origin (exotic vs. native) is relevant to predicting the success of exotic species, and in turn successfully limiting exotic species spread through effective management. We examined the abundance of native and exotic plant species at 56 grasslands in ten countries and experimentally tested how natives and exotics responded to nutrient availability and vertebrate herbivory, two major factors determining grassland plant success. The experiments showed that exotic species were six times more likely to dominate communities than were native species. Nutrient additions reduced the number of native species but left the number of exotic species unaffected, while increasing exotic species abundance (cover). Thus, nutrient availability is a key mechanism fostering the increasing in exotic plant species in grassland. Human activities that increase nutrient inputs are likely to increase the spread of exotic species, and management should seek ways to lessen this impact in order to stem the loss of native grassland plant species diversity.

Technical Abstract: Exotic species currently dominate many communities, but it is unclear if the significance of a species’ origin merely reflects our societal values or if exotic species function differently from the native, resident species. The difficulty in separating these perspectives derives from a lack of systematic assessments of whether species origin is relevant to predicting species responses or function, which in turn obscures management decisions. Here we examine patterns of abundance of native and exotic plant species at 56 grasslands in ten countries, and experimentally test the effects of two fundamental drivers of invasion – resources and vertebrate herbivory – on native and exotic species. We found that exotic species were six times more likely to dominate communities than were native species. In addition, native and exotic species responded differently to experimental nutrient additions. Addition of nitrogen, phosphorus, and other nutrients led to declines in native richness, while leaving exotic richness unaffected. In contrast, addition of nitrogen and phosphorus led to increases in exotic abundance, while native abundance was unaffected. The differential distribution of abundances and distinct response to nutrient additions between native and exotic species suggests that species origin has functional significance for grassland communities, and that ecosystem eutrophication will lead to increases in exotic dominance and a decline in native richness. The effect of nutrients on exotic invasion and domination is particularly problematic, as human endeavors have greatly increased nutrient loading to ecosystems worldwide.