Cirsium pitcheri

Range-wide demographic analysis of Pitcher’s Thistle

Project timeline and status: 2018 - 2023, primary analysis in progress

  1. Cirsium pitcheri, a Federally Listed Threatened Plant

    Pitcher’s thistle (Cirsium pitcheri) is a federally threatened plant endemic to the shores and dunes of the Great Lakes. Cirsium pitcheri is an important floral resource for pollinators in the Great Lakes dune communities and is visited by more insects than any other species in the system. Populations of the plant have experienced long-term declines, likely exacerbated by disturbances from shoreline development and resulting habitat fragmentation.

  2. Quantifying Threats

    This project is determining the range-wide status of the federally listed threatened plant, Cirsium pitcheri, explicitly incorporating threat assessment. Specifically we are quantifying the threats posed by seed predation from biological control agents released to control exotic thistles (Rhinocyllus conicus, Larinus carlinae, and Cleonis pigra) as well as by climate change.  Climate change alters successional dynamics of the habitats, particularly at the southern edge of the species range, causes fluctuations in overall population size in response to lake level dynamics, and may cause the decline in pollination services rendered by native bees. The effects of each of these will be modeled across the life cycle of Cirsium pitcheri, using integral projection models (IPM) across populations that span its range.  We are synthesizing range-wide population monitoring data for Cirsium pitcheri, that has been collected over the last 35 years by a variety of researchers.

  3. Management Action

    Our results will identify management actions that are critical for species recovery and will provide data needed for the Species Status Assessment to be produced by the U.S. Fish and Wildlife Service.

Project Goals

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