Their report, in the December issue of Ecology Letters, suggests it's what's in European soils -- or more specifically, what isn't in them -- that makes it possible for the American black cherry tree to have invaded the continent.

"We're seeing a definite positive effect of European soil on black cherry's growth," said IU biologist Kurt Reinhart, who led the study. "Back in its native range, however, there appears to be something in the soil that prevents the tree from growing easily."

Reinhart's study suggests that in Europe, the invasion of black cherry (Prunus serotina) may actually be helped along by local soil microbes. The study corroborates earlier research showing that American soil microbes inhibit the trees' growth. Pythium, a fungus that causes "damping-off disease" in young trees, is one known genus of black cherry pathogens in the American Midwest.

Black cherry trees, which produce a fruit more often consumed by birds and other wildlife than by humans, have proliferated to such an extent overseas that some concerned Europeans are taking matters into their own hands.

"In parts of Europe, like the Netherlands, Belgium and Germany, the tree is considered quite a pest," said IU biologist Keith Clay, a coauthor of the report. "We are told some Dutch school children are going out on field trips into the woods to pull the tree seedlings and saplings out."

The research team examined the distribution of black cherry trees in four locations -- the Indiana University Research and Teaching Preserve and Griffy Lake Nature Preserve in Bloomington, Ind., and De Ossenbos and De Leeren Doedel in The Netherlands. The scientists also conducted experiments in American and Dutch greenhous
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Contact: David Bricker
brickerd@indiana.edu
812-856-9035
Indiana University
9-Dec-2003