Population ecology of Cirsium pitcheri on Lake Huron sand dunes I. Impact of white-tailed deer

Abstract

Cirsium pitcheri is a monocarpic perennial endemic to the shorelines of the Great Lakes, primarily Lakes Huron and Michigan. Its populations are being reduced by anthropogenic impact and deer grazing throughout much of its range. Several of its once abundant populations at some locations have been extirpated. The species is listed as threatened and endangered in Canada and the United States, respectively. Greenhouse studies were conducted to determine the effects of simulated herbivory by white-tailed deer on the survival, growth, and compensatory ability of plants. We found mat Cirsium pitcheri possessed good ability to compensate for tissue loss. However, simulated intensive browsing resulted in significant reductions in root dry weight. Since the flowering ability of monocarpic perennials such as Cirsium pitcheri is dictated by the amount of stored root reserves, such reductions in root biomass may delay the onset of flowering, reduce overwinter survival, and affect the future growth and survival of this threatened species. Keywords: white-tailed deer, browsing, defoliation, compensation, Cirsium pitcheri, Pitcher's thistle.

Climate Change Impacts on Seedling Establishment for a Threatened Endemic Thistle, Cirsium pitcheri

“…Proposed reasons for population decline include infestation by plume moth (Keddy and Keddy, 1984) and invasive weevils (Havens et al, 2012), browsing by white-tailed deer (Phillips and Maun, 1996;Rowland and Maun, 2001), shoreline development and use of sandy beaches for recreation (Keddy and Keddy, 1984), and fluctuation in lake level and chance events (Bowles et al, 1993). Sheboygan, Wisconsin, approximately midway up the western coast of Lake Michigan.…”

Effects of harvesting and deer browsing on attributes of understory plants in northern hardwood forests, Upper Michigan, USA

“…High deer densities over prolonged periods of time impact understory communities through differential browsing of plant species and by decreasing the frequency of sexual reproduction and fecundity of preferred forage species (Anderson, 1994;Balgooyan and Waller, 1995;Phillips and Maun, 1995). During winter, deer depend on woody browse, while in summer, they feed primarily on nutrient-rich herbaceous species and herbaceous portions of woody plants (Augustine and Jordan, 1998;Balgooyan and Waller, 1995;McCaffrey et al, 1974).…”

“…), especially when stems were protected from deer browsing (Anderson, 1994). Repeated removal of Trillium flowers, fruits, and leaves by deer resulted in decreased flowering and fruiting the following year, and gradual declines in size over progressive years due to reduced production, translocation, and storage of carbohydrate (Anderson, 1994;Phillips and Maun, 1995).…”

Restoration Ecology of an Endangered Plant Species: Establishment of New Populations of Cirsium pitcheri

“…1994; D'Ulisse & Maun 1996; Maun et al . 1996; Phillips & Maun 1996; Maun 1997) have studied critical factors affecting the populations of Cirsium pitcheri ([Torr. Ex.…”