Jolls, Claudia L. , Marik, Julie , Bell, Timothy S. , Havens, Kayri , Fant, Jeremie , Vitt, Pati , McEachern, A. Kathryn , Pavlovic, Noel B. , Bowles, Marlin L. .
Persistence vs. extirpation of Cirsium pitcher, Pitcher's thistle, a rare sand dune endemic of the upper Great Lakes.
Cirsium pitcheri, Pitcher's thistle, is a threatened monocarp of dunes and shorelines of the Great Lakes. Since 2005, we have collaborated to bring together demographic data on more than 12,700 plants at 27 sites, spanning two years to more than two decades. Our goal is to better understand how factors contributing to local demography and genetic composition interact to influence persistence at the population- and regional-levels. Detailed demographic monitoring shows most natural populations are below replacement, including for 9 of the 11 years at one northern MI site (stochastic lambda 0.9101 + 0.0017). We used these long-term data to construct transition matrices and model population viability in the face of demographic stochasticity, inbreeding and catastrophes. The inclusion of inbreeding had the greatest effect on projected population size, not surprising given inbreeding reduces fecundity to ~25% of outcrossed plants. Our experimental and empirical work demonstrates that size, microsite (light, litter), water availability and invasive plants (e.g., baby's breath, Gypsophila paniculata) and insects (biocontrol weevil, Rhinocyllus conicus) can affect survival and fecundity. How these plant responses scale-up to population-level impacts, i.e., weather, drought and even climate change, is less clear. We decomposed elasticity matrices to evaluate plant growth, stasis (persistence) and fecundity on population growth. Cirsium pitcheri populations may be as sensitive to the success of vegetative individuals as to seedling recruitment. Still, the most effective management option for increasing population persistence and viability of Pitcher's thistle is enhanced seedling recruitment. Although populations at the southern end of the range have been extirpated and extant ones may be in decline, restorations appear highly successful in the short term. Given its dependence on long-term (historic Holocene events that formed the Great Lakes shorelines) as well as short-term dynamics of lake-level, Cirsium pitcheri may be a "flash-in-the-pan" Pleistocene relict bound for extinction in a major portion of its range, exacerbated by anthropogenic change.
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Cirsium pitcheri Restoration Project
1 - East Carolina University, Department Of Biology, Howell Science Complex Mail Stop 551, Greenville, NC, 27858-4353, USA
2 - Chicago State University, Department Of Biological Sciences, 9501 South King Drive, Chicago, IL, 60628-1598, USA
3 - Chicago Botanic Garden, CONS SCI DEPT, 1000 Lake Cook Road, Glencoe, IL, 60022, USA
4 - US Geological Survey, Western Ecological Research Center, Channell Islands Field Station, 1901 Spinnaker Dr., Venture, CA, 93001, USA
5 - US Geological Survey Great Lakes Science Center, Western Basin Ecosystems Branch, Public Lands Ecology Section, Lake Michigan Ecological Research Station, 1100 North Mineral Springs Road, Porter, IN, 46304, USA
6 - Morton Arboretum, Research Department, Rt. 53, Lisle, IL, 60532, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Forsyth Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 11:45 AM