Bob, Not much has been published that shows direct evidence of an invasive plant causing the extinction of a native plant. However, much has been implied. Here's a response that I got from Dr. Steve Weller (Univ. of Calif. Irvine):
"I would think about some of the dry forest species that have suffered from repeated fires due to invasive grasses- perhaps Hibiscadelphus hualalaiensis? Stenogyne kanehoana may have gone extinct because of competition from Lantana- assuming it is no longer around. The few plants I saw in 1987 were in a sea of Lantana." If you check out the CPC web page for Stenogyne kanehoana, you'll see this: "Threats: The only known plant does not set seed, and so is unable to naturally reproduce itself. This individual is also embedded in Lantana, an extremely invasive species on the islands of Hawaii. Because of this, the greatest threat to the survival of this species is the encroachment and competition from naturalized, exotic vegetation." http://www.centerforplantconservation.org/ASP/CPC_ViewProfile.asp?CPCNum=4108 The example that I used in my talk at the US Botanic Garden was about competition between Schiedea adamantis and Leucaena leucocephala (Poulin et al., 2005). The Schiedea species is not extinct, but it is getting pushed out by Leucaena. Poulin, J., A. K. Sakai, S. G. Weller, and W. L. Wagner. 2005. Invasive species. Pp. 176-184. In: Kress, W. J. and G. Krupnick (eds.). Plant Conservation: A Natural History Approach. University of Chicago Press, Chicago. The best examples come from the animal world. As Poulin et al write: "The predatory rosy wolf snail (Euglandina rosea) was introduced to the Hawaiian Islands as a biological control agent for the giant African snail (Achatina fulica), another invader. Without managing to control the giant African snail, the rosy wolf snail has caused the extinction of 30 native snail species (Civeyrel and Simberloff 1996)." Hope this helps. Best regards, Gary Gary Krupnick, Ph.D. Head of the Plant Conservation Unit Department of Botany Smithsonian Institution PO Box 37012 NMNH, MRC-166 Washington, DC 20013-7012 USA Tel: 202-633-0940 Fax: 202-786-2563 *** New E-Mail Address*** E-mail: [EMAIL PROTECTED]
