Effects of salinity on seedling performance of a native Louisiana iris, Iris hexagona relative to an invasive Iris pseudacorus.
Wiens, Karen*,1, Mopper, Susan 1, 1 University of Louisiana, Lafayette, Lafayette, LA
ABSTRACT- The degree of competition between native and invasive species may shift as global warming alters environments in which their interactions occur. Such changes may impact the relative population size and distribution of native and invasive species. We tested interactions between Iris hexagona, native to coastal Louisiana marshes, and Iris pseudacorus, a species originating from Eurasia now considered invasive in 43 of the lower 48 states and in Canada. Both species reproduce sexually and clonally, and are glycophytic, with overlapping salinity tolerance. We found that under freshwater and increased salinity (3, 6, and 9 ppt) conditions, I. pseudacorus seeds germinated earlier and seedlings grew faster than I. hexagona, some becoming rhizomatous before the native iris germinated. Our results indicate that invasive I. pseudacorus may have an advantage over native I. hexagona in its ability to establish through sexual reproduction.
Key words: invasive species, competition, sexual reproduction
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