ARS | Publication request: Abundance of introduced species at home predicts abundance away in herbaceous grasslands

Submitted to: Ecology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 2010
Publication Date: February 18, 2011
Citation: Firn, J., Moore, J.L., MacDougall, A.S., Borer, E.T., Seabloom, E.W., Hillerislambers, J., Harpole, W.S., Cleland, E.E., Brown, C.S., Knops, J.M., Prober, S.M., Pyke, D.A., Farrell, K.A., Bakker, J.D., O'Halloran, L.R., Adler, P.B., Collins, S.L., D'Antonio, C.M., Crawley, M.J., Wolkovich, E.M., La Pierre, K.J., Melbourne, B.A., Hautier, Y., Morgan, J.W., Leakey, A.D., Kay, A., McCulley, R., Davies, K., Stevens, C.J., Chu, C., Holl, K.D., Klein, J.A., Fay, P.A., Hagenah, N., Kirkman, K.P., Buckley, Y.M. 2011. Abundance of introduced species at home predicts abundance away in herbaceous grasslands. Ecology Letters. 14:274-281.

Interpretive Summary: This manuscript compares the abundance of invasive plant species in their native ranges versus in their introduced ranges. A widely held assumption is that invasive plant species are more abundant where they have invaded, compared to their abundance in their native ranges, because of several reasons including release from native natural enemies and competitive interactions with native community members. This assumption was tested using a unique world wide dataset on species composition in grassland, which included 39 temperate grasslands in eight countries whose plant communities were sampled using identical methods. The analysis did not support the common assumption. Invasive plant species abundance was generally similar in its native and introduced ranges, and in fact the two were correlated. This result increases our understanding of global change impacts on grasslands by suggesting that not all introduced species will expand to large areas in their introduced ranges. This fact will be important in designing improved biosecurity programs.

Technical Abstract: Many ecosystems worldwide are dominated by introduced plant species, leading to loss of biodiversity and ecosystem function. A common but rarely tested assumption is that these plants are more abundant in introduced versus native communities, because ecological or evolutionary based shifts in populations underlie invasion success. Here data for 26 herbaceous species in 39 temperate grasslands, within eight countries, revealed that species abundances were similar at native (home) and introduced (away) sites—grass species were generally abundant home and away, while forbs were low in abundance, but more abundant at home. Sites with six or more of these species had similar community abundance hierarchies, suggesting suites of introduced species are assembling similarly on different continents. Overall, we found substantial changes to populations are not necessarily a pre-condition for invasion success and that increases in species abundance are unusual. Instead, abundance at home predicts abundance away, a potentially useful measure for biosecurity programs.