White, Hadiya , Bell, Timothy .
Factors affecting survivorship and survival time of transplants and their natural descendents of the federally threatened Pitcher’s thistle (Cirsium pitcheri).
Pitcher’s thistle (Cirsium pitcheri) is an endemic species of the great lakes region that colonizes shores, fore dunes and recent blowouts. A monocarpic perennial, it was once a component of the Illinois dune community until extirpation in the early 1900s. In 1991, this federally threatened species was reintroduced at Illinois Beach State Park in an effort to establish sustainable populations within its former habitat. Establishment of viable populations is inhibited by the necessity of large seedling cohorts and the short life span of Cirsium pitcheri. We used logistic regression and survival analysis to reexamine long term demographic data from the C. pitcheri reintroduction to determine what factors affected survivorship and survival time of transplants and their natural descendents. Survivorship and survival time significantly increased with transplant size. A significant decrease in survival and survival time occurred for individuals growing in the interdune versus the dune. There was no significant difference in transplant survival between habitats that differ in disturbance but transplants in the more disturbed habitat exhibited a significantly shorter lifespan. The significant difference in survivorship between transplants and natural recruits disappeared when start year size was added as an independent variable, indicating that size may account for the differences in survivorship between transplants and natural recruits. Factors affecting survivorship and survival time varied from year to year and appeared to be related to drought severity. Understanding the factors that affect transplant survivorship and survival time will improve the success of future reintroductions.
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1 - Governors State University, Department of Biology, 1 University Parkway, University Park, Illinois, 60466, USA
2 - Chicago State University, Biological Sciences, 9501 South King Drive, Chicago, Illinois, 60628, USA
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM