Denoth, Madlen Myers, Judith H. 2006-11-23 The rare endemic plant <i>Sidalcea hendersonii</i> (Henderson’s checker-mallow) occurs in tidal marshes of the Pacific Northwest and may be threatened by <i>Lythrum salicaria</i> (purple loosestrife), a European invader plant. We compared the abundances of <i>Lythrum</i> and <i>Sidalcea</i> in a wetland in British Columbia (Canada) in 1999 to those measured in 1979 to track changes in both species. Although the frequency of <i>Sidalcea</i> decreased by more than 50%, and that of <i>Lythrum</i> increased by almost 20%, there was no significant relationship between the changes of the two species. We assessed the potential effects of competition by <i>Lythrum</i> on <i>Sidalcea</i> in field and patio experiments. In the field, we measured the response of <i>Sidalcea</i> to the removal of <i>Lythrum</i> over a two-year period and compared this to the response of <i>Sidalcea</i> to the removal of native species and in unmanipulated control plots. Removal of <i>Lythrum</i> significantly improved the vegetative performance of <i>Sidalcea</i> compared to the removal of randomly selected native plants and the control treatment in the first year. In the second year, the performance of <i>Sidealcea</i> did not differ significantly with treatment. Removals did not influence the reproductive performance of <i>Sidalcea</i> in either year. A one-year additive experiment, carried out in pots, compared the competitive effect of <i>Lythrum</i> on <i>Sidalcea</i> with that of two native species. <i>Lythrum</i>’s impact on <i>Sidalcea</i> was not consistently stronger than that of the native species. Collectively, these results do not indicate a strong impact of <i>Lythrum</i> on the reproduction or abundance of <i>Sidalcea</i>. application/pdf https://folia.unifr.ch/global/documents/300548 https://folia.unifr.ch/documents/300548/files/11258_2006_Article_9232.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1007/s11258-006-9232-2 info:eu-repo/semantics/openAccess License undefined Plant Ecology. - 2007, vol. 191, no. 2, p. 153-161 invasive plant purple loosestrife removal experiment Sidalcea hendersonii tidal wetland info:eu-repo/classification/udc/57 Competition between Lythrum salicaria and a rare species : combining evidence from experiments and long-term monitoring http://purl.org/coar/resource_type/c_6501