UNC ecologists find floodplains particularly vulnerable to invasion by exotic pla...( One might think that because they are i...)

One might think that because they are irregularly drowned and flushed with water, floodplains -- despite their fertility -- would contain fewer plant species than more protected upland areas. A new University of North Carolina at Chapel Hill study shows, however, that that's not so.

By scouring North Carolina's southern Appalachian forests and examining the plants and conditions found there, UNC researchers have discovered that species diversity is significantly greater for both native and exotic plants in floodplains than in the higher areas. One reason appears to be that floodwater washes away significant numbers of plants and thereby creates opportunities for newcomers. Another is that water and gravity combine to transport seeds from upstream sources and deposit them on floodplains.

Of particular concern is the observation that such floodplains, which scientists call riparian areas, contain up to 40 times more exotic species than comparable habitats on adjacent uplands. Such information is important, the researchers say, because it offers insight into how invasive plant species from other continents interact with native plants and ultimately replace them.

A report on the findings appears in the current issue of Ecology, a top scientific journal. Authors are Dr. Rebecca L. Brown, a former UNC graduate student and now a postdoctoral fellow at the Patrick Center for Environmental Research at the Academy of Natural Sciences in Philadelphia, and Dr. Robert K. Peet, professor of biology at UNC.

"Exotic species invasion is one of the major ecological problems of our time because they change habitats and could potentially cause many native species to go extinct," Brown said. "A leading theory in ecology has been that in areas with a high species diversity there should be less invasion by exotic species, but we found that's often not true."

In the study, which she conducted for her doctorate under Peet's supervision, the two exa
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Contact: David Wiliamson
919-962-8596
University of North Carolina at Chapel Hill
11-Feb-2003

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