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      • HARVEST
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      Evaluating threats and management practices for the conservation of hairy prairie-clover (Dalea villosa Nutt. (Spreng) var. villosa), a rare plant species in Saskatchewan

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      CATELLIER-THESIS.pdf (4.917Mb)
      Date
      2013-03-14
      Author
      Catellier, Christiane
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      Hairy prairie-clover (Dalea villosa Nutt. (Spreng) var. villosa), a rare plant species, grows in the Canadian Prairies. Populations of Dalea in Canada are threatened by the loss of sand dune habitat because of changes in land use and altered ecological processes such as grazing and fire. Local populations of Dalea are further threatened by one or more specific threats, including herbivory from native and domestic ungulates and invasion of habitats by exotic plants. The overall objective of this thesis was to gain more knowledge about Dalea and to determine the impact of threats and management practices to the Saskatchewan populations and their habitats. Observational studies were conducted at each of two sites in Saskatchewan supporting Dalea. First, at the Dundurn Sandhills site, structural equation modeling was used to examine landscape, ecological, and management factors associated with high rates of herbivory on Dalea and with reductions in the long-term survival and productivity of Dalea. The conditions which deer (Odocoileus hemionus and Odocoileus virginianus) or cattle (Bos taurus) were responsible for the most intense rates of herbivory to Dalea plants and patches were determined. Generally, deer appeared responsible for the most herbivory, whereas cattle grazing on Dalea increased with stocking densities. At the same time, new hypotheses about ecological processes affecting Dalea productivity in the Dundurn Sandhills were explored. In particular, it appeared that deer may be responding to cattle grazing in Dalea habitat by avoiding those areas, and that mid-season germination and recruitment of many Dalea plants may occur following precipitation events. Second, at the Mortlach site, the costs and benefits of using grazing management to control leafy spurge (Euphorbia esula L. var. esula) were assessed, especially in consideration of the potential negative effects of intense herbivory on Dalea productivity. Aspects of the grazing regime including stocking density and the livestock species influenced herbivory on Dalea and its reproductive output, but there were no apparent links between the abundance of leafy spurge abundance and the reproductive output of Dalea. The findings of these two studies are relevant for the conservation and management of Dalea in Saskatchewan.
      Degree
      Master of Science (M.Sc.)
      Department
      Plant Sciences
      Program
      Plant Science
      Supervisor
      Lamb, Eric
      Committee
      Henderson, Darcy; Romo, Jim; Coulman, Bruce
      Copyright Date
      December 2012
      URI
      http://hdl.handle.net/10388/ETD-2012-12-810
      Subject
      Dalea villosa
      hairy prairie-clover
      SEM
      herbivory
      grazing
      leafy spurge
      Euphorbia esula
      multi-model inference
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