Physiological and morphological responses of pine and willow saplings to post-fire salvage logging

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dc.contributor.authorMillions, Elizabeth L.
dc.contributor.supervisorLetts, Matthew G.
dc.date.accessioned2015-05-11T22:29:27Z
dc.date.available2015-05-11T22:29:27Z
dc.date.issued2015
dc.degree.levelMastersen_US
dc.description.abstractWith global warming, forest fires may be increasing in frequency, and subsequently post-fire salvage logging may become more common. The ecophysiological impacts of this practice on tree saplings remain poorly understood. In this study, I examined the physiological and morphological impacts of increased light intensity, due to post-fire salvage logging, on the conifer Pinus contorta (pine) and deciduous broadleaf Salix lucida (willow) tree and shrub species in the Crowsnest Pass region of southern Alberta. Photosynthetic gas-exchange and plant morphological measurements were taken throughout the summer of 2013 on approximately ten year-old saplings of both species. Neither species exhibited photoinhibition, but different strategies were observed to acclimate to increased light availability. Willow saplings were able to slightly elevate their light-saturated rate of net photosynthesis (Amax) when exposed to higher photosynthetic photon flux density (PPFD), thus increasing their growth rate. Willow also exhibited increased leaf inclination angles and leaf mass per unit area (LMA), to decrease light interception in the salvage-logged plot. By contrast, pine, which exhibited lower Amax and transpiration (E), but higher water-use efficiency (WUE = Amax/E) than willow, increased the rate at which electrons were moved through and away from the photosynthetic apparatus in order to avoid photoinhibition. Acclimation indices were higher in willow saplings, consistent with the hypothesis that species with short-lived foliage exhibit greater acclimation. LMA was higher in pine saplings growing in the logged plot, but whole-plant and branch-level morphological acclimation was limited and more consistent with a response to decreased competition in the logged plot, which had much lower stand density.en_US
dc.description.sponsorshipNSERC Discovery Grant (Plant physiological response to environmental stress in semiarid ecosystems)en_US
dc.embargoNoen_US
dc.identifier.urihttps://hdl.handle.net/10133/3680
dc.language.isoen_CAen_US
dc.proquest.subject0478en_US
dc.proquest.subject0329en_US
dc.proquest.subject0768en_US
dc.proquestyesYesen_US
dc.publisherLethbridge, Alta. : University of Lethbridge, Dept. of Geographyen_US
dc.publisher.departmentDepartment of Geographyen_US
dc.publisher.facultyArts and Scienceen_US
dc.relation.ispartofseriesThesis (University of Lethbridge. Faculty of Arts and Science)en_US
dc.subjectplant physiologyen_US
dc.subjectplant stress ecologyen_US
dc.subjectphotosynthesisen_US
dc.subjectsalvage loggingen_US
dc.subjectstable isotope ecologyen_US
dc.subjectstress acclimationen_US
dc.subjectsubalpineen_US
dc.subjectRocky Mountainsen_US
dc.subjectAlbertaen_US
dc.subjectforestryen_US
dc.subjectecophysiologyen_US
dc.subjectpineen_US
dc.subjectwillowen_US
dc.titlePhysiological and morphological responses of pine and willow saplings to post-fire salvage loggingen_US
dc.typeThesisen_US
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