Thesis (M.S.)--Oregon State University, 2000. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (MS)--University of Montana, 2010. / Contents viewed on May 28, 2010. Title from author supplied metadata. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1985. / Typescript (photocopy). Includes bibliographical references (leaves 151-161). Also available on the World Wide Web.

Regeneration of forest stands is often complicated by the establishment and competition of brush on logged and burned-over areas. The encroachment of brush in the ponderosa pine type of Idaho, particularly Ceanothus velutinus, Dougl. presents a difficult problem to the forest manager. The brush competition severely reduces the growth rate of associated trees, thus extending the period necessary to grow a crop of trees. This situation may seriously limit the economic production of a wood crop of ponderosa pine. Any approach to the solution of brush problems should include a thorough understanding of brush ecology. Those phases of ecology dealing with reproduction and distribution of brush need special emphasis. It has been assumed that most of the brush on logged or burned-over areas originated from seed stored in the forest floor; yet little is known of the quantity or distribution of these seeds. This study was carried out to learn what kind, number and variability of seed is present in the forest floor, and to investigate the number of seed located in different forest conditions, aspects and soil layers. To achieve the above objectives, 48 square-foot, duff-soil samples were taken in the ponderosa pine type of the Boise Basin Experimental Forest in Idaho. Seeds were separated from the samples and major species identified, pretreated and germinated. Appropriate statistical techniques were employed to determine significant results among the different forest conditions, aspects and soil layers sampled.

An earlier publication presented evidence for enhancement of isocitrate lyase (threo-L_S isocitrate glyoxylate lyase, EC 4.1.3.1) activity by a factor that diffuses into the megagametopnyte from the embryo of stratified germinating Pinus ponderosa seeds. In contrast, the data reported here indicate the rate of increase in specific activity of embryoless seeds was greater during the first four days than in seeds with embryos left in situ. A similar pattern of activity was observed in seeds which retained their embryos for two days to allow germination to occur prior to excision, but the peak activity was slightly nigher. The highest enzyme activity was achieved in seeds which retained their embryos the longest. A model is included to resolve these apparently diverging effects of the embryo on isocitrate lyase activity. A diffusate prepared from two day germinated embryos had no significant influence on the enzyme activity of embryoless seeds. The phenomena reported here were not dependent on stratification. Imbibition was the only prerequisite for germination and develooment of enzyme activity to occur. / Master of Science

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Thesis (M.S.)--Oregon State University, 2003. / Typescript (photocopy). Includes bibliographical references (leaves 85-92). Also available online.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 93-100). Also available on the World Wide Web.