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Biol Invasions (2012) 14:26172624 DOI 10.1007/s10530-012-0257-2
ORIGINAL PAPER
Do priority effects benet invasive plants more than native plants? An experiment with six grassland species
Timothy L. Dickson Jennifer L. Hopwood
Brian J. Wilsey
Received: 7 August 2011 / Accepted: 28 May 2012 / Published online: 13 June 2012 Springer Science+Business Media B.V. 2012
Abstract Invasive, non-native plant species often outcompete native species and reduce biodiversity. Invasive plants frequently begin growth before native plants, yet few studies have examined whether invasives win in competition partly by colonizing disturbed sites more quickly or by beginning growth earlier in the season than native plants (i.e. due to priority effects). We hypothesized that invasive plant species would benet more from priority effects than would comparable native species and that earlier growth of invasive
species would decrease plant biodiversity. To test this hypothesis, we grew three pairs of invasive and native plant species from three different functional groups/ plant families (C3 grasses/Poaceae, non-leguminous forbs/Asteraceae, and legumes/Fabaceae). We seeded each of the species 3 weeks before seeding the other ve species into large pots in a greenhouse. Consistent with our hypothesis, we found much stronger priority effects with invasive than native species. Each invasive species formed a near-monocultures when seeded rst(97.5 % of total biomass, on average) whereas native species did not similarly dominate (29.8 % of total biomass, on average). Similarly, Simpsons species diversity was 81 % higher when the initially sown species was native rather than invasive. The literature suggests that invasive species in the eld often begin growth earlier in the spring than native species and that climate change may increasingly allow invasives to begin growth before native species, indicating invasive priority effects may become increasingly common.
Keywords Dominance Earlier growth
Exotic species Non-native species
Plant invasion Priority effect
Introduction
Faster growth, greater fecundity, and other mechanisms are proposed to explain the superior competitive ability of invasive plant species (Pyek and
Electronic supplementary material The online version of this article (doi:http://dx.doi.org/10.1007/s10530-012-0257-2
Web End =10.1007/s10530-012-0257-2 ) contains supplementary material, which is available to authorized users.
T. L. Dickson J. L. Hopwood B. J. Wilsey
Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA e-mail: [email protected]
J. L. Hopwoode-mail: [email protected]
B. J. Wilseye-mail: [email protected]
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