Conservation of Oenothera wolfii (Onagraceae) : \ud introducing a threatened plant into two protected locations in Oregon

Graduation date: 2007The showy biennial to short-lived perennial Oenothera wolfii (Munz) Raven, Dietrich & Stubbe (Wolf’s evening primrose) occurs in only a small number of isolated populations on the southern Oregon and northern California coast. This rare species is currently listed as Threatened in Oregon, and is considered a Species of Concern by the U.S. Fish and Wildlife Service. Its status results from having a limited geographical and ecological range while facing several threats, including habitat loss and hybridization with an escaped garden cultivar, O. glazioviana. In order to promote the conservation of O. wolfii and assess the feasibility of introducing new populations within the historic range of this species, plants were cultivated in the greenhouse and transplanted to two experimental field sites on the southern Oregon coast. In the course of this study, seed germination, cultivation and transplanting protocols, as well as site selection criteria, were developed or refined. Additionally, the survival and reproductive success of transplanted rosettes of various sizes were evaluated and transplant success in weeded versus unweeded plots was compared. While rosette size did not affect transplant survival, larger transplants were more likely to reproduce in the first year after transplanting and to have larger numbers of flowering stalks, flowers and seeds than smaller transplants. Transplants were more reproductively successful in plots from which ground cover was removed at the time of transplanting. Overall, transplants were more successful at the southernmost site, which was located on the bluff immediately above the ocean beach on relatively stable substrate, as opposed to the northern site, which was located approximately one kilometer inland on open, moving sand dunes. Based on initial results, the introduction and establishment of new populations of O. wolfii appears to be possible. The knowledge regarding the successful cultivation and transplantation of this species reported in this thesis will be useful for future introduction projects