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Environmental Influences on Gas Exchange in Fertilized and Non-Fertilized Stands of Loblolly Pine

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dc.contributor.authorGough, Christopher Michaelen
dc.contributor.committeechairSeiler, John R.en
dc.contributor.committeememberChevone, Boris I.en
dc.contributor.committeememberMou, Paul P.en
dc.contributor.departmentForestryen
dc.date.accessioned2014-03-14T20:42:29Zen
dc.date.adate2000-08-14en
dc.date.available2014-03-14T20:42:29Zen
dc.date.issued2000-07-27en
dc.date.rdate2001-08-14en
dc.date.sdate2000-08-02en
dc.description.abstractSpatial and temporal variation in foliar gas exchange on both a diurnal and seasonal scale was examined in 15-year-old fertilized and non-fertilized loblolly pine in the upper and lower thirds of crowns in stands located in the North Carolina sandhills. Photosynthesis rates between control and fertilized stands for both seasonal and diurnal measurement periods were different during only three months. Photosynthesis rates were consistently greater in the upper third of the crown compared to the lower third. Seasonal trends in both conductance and transpiration closely resembled trends found in seasonal photosynthesis. Foliar nitrogen concentrations were greater in fertilized stands for all months sampled. However, nitrogen content generally did not correlate with photosynthesis rates. Mean monthly water use efficiencies were significantly higher in fertilized stands during two months and were usually greater in upper crown foliage. Common empirical gas exchange models reveal that light and vapor pressure deficit (VPD) explain a majority of the variation observed in photosynthesis and transpiration, respectively. Conductance was not modeled since environmental variation did not adequately explain conductance patterns. Predicted light response curves reveal that upper crown foliage has higher maximum photosynthesis rates, respiration rates, light compensation points, and lower initial quantum yield compared to lower crown foliage. Models predict that foliage from fertilized stands is more sensitive to VPD and light during the growing season. Transpiration models predict highly variable responses to VPD depending on the treatment combination and season. Model R-square and predicted gas exchange values suggest that seasonal acclimation occurred.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-08022000-11480057en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08022000-11480057/en
dc.identifier.urihttp://hdl.handle.net/10919/34301en
dc.publisherVirginia Techen
dc.relation.haspartGoughthesis.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectseasonal and diurnal variationen
dc.subjectLoblolly Pineen
dc.subjectenvironmenten
dc.subjectcrown positionen
dc.subjectfertilizationen
dc.subjectgas exchangeen
dc.titleEnvironmental Influences on Gas Exchange in Fertilized and Non-Fertilized Stands of Loblolly Pineen
dc.typeThesisen
thesis.degree.disciplineForestryen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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