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Abstract Detail


Ecological Section

Jolls, Claudia L. [1], Marik, Julie E. [1], Hamze, Samara I. [2], McEachern, Kathryn [3].

Population dynamics, invasives and possible impacts on a rare dune endemic of the Great Lakes, Pitcher’s thistle.

An understanding of plant population dynamics is needed for rare species management, in response to both natural and anthropogenic influences. We here summarize 8 yr of long-term study on a Great Lakes dune monocarpic endemic, Cirsium pitcheri, in northern Michigan, including changes in the demography of Pitcher’s thistle from the invasive baby’s breath, Gypsophila paniculata. The negative effects of this and other invasives may be due to light reduction and litter accumulation. We experimentally manipulated light and litter levels in a controlled environment to determine the effect on seedlings and ultimately, population performance. We germinated 5295 seeds and assigned them to one of six treatments, including full light or 30% reduction, with monocot or dicot litter applied to a depth of 0.5 cm, or no litter, 4 replicate pots each. We used these germination rates as the reproductive element of a size-base matrix to model population growth and viability. The absence of shading and litter increased seedling emergence from 8-26% to 42%. Population viability also increased in the absence of shade and litter; however, no simulated population lasted for more than 49 yr, indicating this population of C. pitcheri is non-viable, strictly speaking, even under ideal conditions. Cirsium pitcheri most likely persists on the landscape as metapopulations. The few large populations remaining on protected lands may act as source populations; their loss to exotics and increased habitat destruction and fragmentation could increase species extinction risk. Control of invasives and addition of greenhouse transplants to increase recruitment can help reverse population declines.


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1 - East Carolina University, Department of Biology, Howell Science Complex, Greenville, North Carolina, 27858-4353, USA
2 - University of Wisconsin-Oshkosh, Department of Biology & Microbiology, 800 Algoma Blvd., Oshkosh, WI, 54901-8640, USA
3 - USGS, Western Ecological Research Center, Channel Islands Field Station, 1901 Spinnaker Drive, Ventura, CA, 93001

Keywords:
rare plants
Invasive plants
demography
dunes
Germination
shade
litter
population viability analysis
Cirsium pitcheri
Gypsophila paniculata.

Presentation Type: Oral Paper:Papers for BSA Sections
Session: 5
Location: Wasatch B/Cliff Lodge - Level C
Date: Monday, July 27th, 2009
Time: 8:15 AM
Number: 5002
Abstract ID:230


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