The finding is bad news for land managers seeking a way to control the introduced grass. Fire was thought to be one way to restore native grasses and prevent further spread of the non-native species.

Regardless of the time of year Lehmann lovegrass was burned, the grass grew back and, in some cases, increased in amount, report ecologists from the University of Arizona in Tucson.

"We had hoped to find that something would reduce the non-native species, or favor the native over it, which is not what we see," said Erika L. Geiger, a doctoral candidate in UA's School of Natural Resources.

Geiger will give her presentation, "Maintaining grasslands: the interaction of fire, climate, and non-native species," on Thursday, Aug. 5, at 1:30 p.m. in Room B110 of the Oregon Convention Center in Portland, Ore., at the annual meeting of the Ecological Society of America. Guy R. McPherson, a UA professor of natural resources, is a co-author on the presentation. The research was funded by the U.S. Department of Defense.

Natural resource managers have been looking for ways to manage the spread of Lehmann lovegrass, also known as Eragrostis lehmanniana. The exotic grass, introduced in the Southwest during the 1930s to control erosion and to feed livestock, has been slowly taking over native grasslands ever since.

Non-native species can alter ecosystems by supplanting native species. The consequences of having a non-native species present depend on its characteristics and the way it interacts with the ecological community it's invading.

"Success of biological invasions is species- and site-specific," McPherson said. Besides replacing the natives, introduced plants could permanently alter the characteristics of an ecosystem by affecting such processes as nutrient cycling and relationships between species.
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Contact: Mari N. Jensen, UA News Services
mnjensen@email.arizona.edu
520-626-9635
University of Arizona
1-Aug-2004