Knight, Tiffany , Vitt, Pati , Kendall, Bruce .
Control of invasive shrubs and herbivores required to conserve an endangered annual plant, Tomanthera auriculata (Scrophulariaceae), in prairie fragments near Chicago, Illinois, USA.
INVASIVE species are the second most important cause of endangerment of rare plants in the US. In the Midwestern US, prairies were formerly maintained as grasslands through fire and large grazers. Present prairie remnants are heavily invaded by woody shrubs (many exotic) and browsed by overabundant mammalian herbivores. We collected demographic data on Tomanthera auriculata, an herbaceous annual with a short lived (∼ 3 year) seedbank, for four years from five sites near Chicago, Illinois, USA. These sites, which are all managed differently, vary in their frequency of brush removal and in their intensity of deer browse. We found that, in a year following brush removal, the mean size of Tomanthera plants and the mean per-capita fruit production increased by 65%. Individuals that were browsed by deer had about 1/3 the fruit production of unbrowsed plants, regardless of size. Across four of the sites, all of the inter-annual and among-site variation in demography could be explained by the presence/absence of brush removal and the intensity of deer browse. By constructing a demographic model that includes the seed bank dynamics, we show that, while brush control and deer control would each improve the status of the Tomanthera population, at most sites both types of invasive species need to be controlled to ensure that the population growth rate (λ) is greater than one.
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1 - Washington University in St. Louis, Department of Biology, One Brookings Dr. Box 1229, McDonnell 407, St. Louis, Missouri, 63130, USA
2 - Institute for Plant Conservation, Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, Illinois, 60022, USA
3 - Donald Bren School of Environmental Science and Management, Bren Hall 4514, University of California, Santa Barbara, California, 93106-5131, USA
rare plant conservation
Presentation Type: Poster:Posters for Topics
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM