{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/34301"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/34301","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Environmental Influences on Gas Exchange in Fertilized and Non-Fertilized Stands of Loblolly Pine","abstract":"Spatial 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.","abstract_html":"Spatial 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.","abstract_has_math":false,"creators":["Gough, Christopher Michael"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Forestry","degree_department":"Forestry","school":null,"contributors":[],"advisors":[],"committee_chairs":["Seiler, John R."],"committee_members":["Chevone, Boris I.","Mou, Paul P."],"year":2000,"date_issued":"2000-07-27","date_published":"2000-07-27","updated_at":"2026-07-22T22:18:49Z","subjects":["seasonal and diurnal variation","Loblolly Pine","environment","crown position","fertilization","gas exchange"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-08022000-11480057"],"render_values":[{"text":"etd-08022000-11480057","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/34301","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Seiler, John R."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Chevone, Boris I.","Mou, Paul P."]},{"key":"dc:contributor.department","label":"Department","values":["Forestry"]},{"key":"dc:creator","label":"Author","values":["Gough, Christopher Michael"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:42:29Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:42:29Z","2001-08-14"]},{"key":"dc:date.issued","label":"Date","values":["2000-07-27"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Forestry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["seasonal and diurnal variation","Loblolly Pine","environment","crown position","fertilization","gas exchange"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-08022000-11480057"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/34301"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Spatial 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."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:title","label":"Title","values":["Environmental Influences on Gas Exchange in Fertilized and Non-Fertilized Stands of Loblolly Pine"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Seiler, John R."],"dc:contributor.committeemember":["Chevone, Boris I.","Mou, Paul P."],"dc:contributor.department":["Forestry"],"dc:creator":["Gough, Christopher Michael"],"dc:date.accessioned":["2014-03-14T20:42:29Z"],"dc:date.available":["2014-03-14T20:42:29Z","2001-08-14"],"dc:date.issued":["2000-07-27"],"dc:description.abstract":["Spatial 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."],"dc:description.degree":["Master of Science"],"dc:identifier.other":["etd-08022000-11480057"],"dc:identifier.uri":["http://hdl.handle.net/10919/34301"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["seasonal and diurnal variation","Loblolly Pine","environment","crown position","fertilization","gas exchange"],"dc:title":["Environmental Influences on Gas Exchange in Fertilized and Non-Fertilized Stands of Loblolly Pine"],"dc:type":["Thesis"],"thesis:degree_discipline":["Forestry"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:18:49Z"}