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dc.contributor.authorBeier, Colin Mitchellen_US
dc.date.accessioned2014-03-14T20:41:26Z
dc.date.available2014-03-14T20:41:26Z
dc.date.issued2002-07-01en_US
dc.identifier.otheretd-07142002-181320en_US
dc.identifier.urihttp://hdl.handle.net/10919/34000
dc.description.abstractSuppression of canopy tree recruitment beneath rapidly spreading thickets of Rhododendron maximum L. (Ericaceae) in southern Appalachian forests is an issue of major concern because of the potential impacts on forest productivity, hydrology and wildlife habitat. Many studies have investigated the causes of seedling inhibition beneath dense shrub understories, but few have uncovered specific mechanisms leading to seedling decline. In this study, I have examined the influence of the evergreen understory (R. maximum and Kalmia latifolia L.) on tree recruitment processes at multiple stages - seed rain, seed bank, and post-establishment seedling growth and survivorship. Effects of dense shrub cover on seed rain and seed bank density and composition were examined using a paired treatment design in which samples were collected beneath shrub-influenced and open understories. A second experiment investigated the influence of R. maximum and K. latifolia density on the growth and survivorship of Quercus seedlings, resource availability, and the rates / causes of seedling damage. I found that neither seed rain, nor seed bank density or species richness was inhibited by the presence of R. maximum or K. latifolia. Forest seed banks were dominated by sweet birch (Betula lenta L.), and were compositionally disparate from the overstory. Analysis of resource competition between shrubs and seedlings indicated that seedling performance and survivorship was a negative function of R. maximum density. Open-canopy light availability, nitrogen content in the organic horizon (litter and humus), and soil nutrient availability were potential resource-related mechanisms. Further, I found that the rates of insect herbivory on Quercus seedlings were positively correlated with R. maximum density. Kalmia latifolia had little influence on resource availability, seedling performance or herbivory rates, and does not appear to have a suppressive effect on tree seedlings. Overall, this research indicates that resource competition is the primary mechanism by which seedling suppression occurs beneath R. maximum, and that increased herbivory on seedlings may be an additional mechanism that demands further study.en_US
dc.publisherVirginia Techen_US
dc.relation.haspart03_thesisbody.PDFen_US
dc.relation.haspart01_title_page.PDFen_US
dc.relation.haspart02_front_material.PDFen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectresource competitionen_US
dc.subjectherbivoryen_US
dc.subjectRhododendron maximumen_US
dc.subjecttree recruitmenten_US
dc.titleThe Influence of Dense Understory Shrubs on the Ecology of Canopy Tree Recruitment in Southern Appalachian Forestsen_US
dc.typeThesisen_US
dc.contributor.departmentBiologyen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineBiologyen_US
dc.contributor.committeechairNilsen, Erik T.en_US
dc.contributor.committeememberJones, Robert H.en_US
dc.contributor.committeememberSeiler, John R.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-07142002-181320/en_US
dc.date.sdate2002-07-14en_US
dc.date.rdate2003-07-23
dc.date.adate2002-07-23en_US


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