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dc.contributor.advisorDeLuca, Thomas H
dc.contributor.authorPingree, Melissa Rose Ann
dc.date.accessioned2017-05-16T22:12:56Z
dc.date.available2017-05-16T22:12:56Z
dc.date.submitted2017-03
dc.identifier.otherPingree_washington_0250E_16830.pdf
dc.identifier.urihttp://hdl.handle.net/1773/38626
dc.descriptionThesis (Ph.D.)--University of Washington, 2017-03
dc.description.abstractThe rain shadow forests of the Olympic peninsula represent a unique, mixed-severity fire regime class in the midst of a highly productive landscape where spatial heterogeneity of fire severity may have significant implications for below and aboveground post-fire recovery. The purpose of this study was to quantify the impacts of wildfire on forest carbon (C) and nitrogen (N) pools and assess the influence of charcoal in a mixed-severity ecosystem on the Olympic Peninsula, Washington, USA. We established a fire chronosequence in forest stands ranging in time since fire (TSF) from 3 to 115 years prior to site establishment. At each site, we measured vegetation abundance, overstory composition, and attributes of surface mineral soil to a depth of 10 cm and forest floor organic matter that included pH, texture, bulk density, and C and N pools (dissolved organic C [DOC], phenol, ammonium, nitrate). Non-ionic resin lysimeters were buried at the interface of organic and mineral soil to measure the O-horizon leached DOC that would contact charcoal particles on the forest floor. Charcoal particles collected from the chronosequence sites were used in adsorption batch experimentation with phenol as a sorbate and measured an average 29.70 (± 6.23) μg phenol mg charcoal-1 adsorption capacity, which did not differ significantly between chronosequence sites. Wildfire-produced charcoal along the chronosequence showed high variability in adsorption capacity, which was partially explained by the thermogravimetric region of volatilized adsorbed compounds onto charcoal surfaces. The O-horizon leachate averaged 1.05 (SD ± 2.87) g DOC m-2 year-1 and increased significantly along the TSF gradient (Pearson’s r = 0.52; p < 0.0001). Multivariate, non-parametric analysis of soil and vegetation factors showed a significant relationship with the time since fire gradient between sites (p-value < 0.01) but not within sites. The TSF gradient was significantly correlated to charcoal mass in the O-horizon (r = -0.4), O-horizon C (r = 0.4), phenolic content in both O-horizon (r = 0.4) and mineral soils (r = 0.2), and potentially mineralizable N (r = 0.4). Recent sites contained higher mineral soil total N and inorganic available N, though not significantly correlated with the TSF gradient. Over time, soils appear to shift toward phenolic-rich organic and mineral soils, higher moss cover, and a higher potentially mineralizable nitrogen index. This study provides evidence of a multivariate, belowground soil response that is less sensitive to wildfire disturbances than the aboveground vegetation.
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.rightsnone
dc.subjectBlack Carbon
dc.subjectCharcoal
dc.subjectFire Ecology
dc.subjectForest Ecology
dc.subjectNitrogen Cycling
dc.subjectPryogenic Carbon
dc.subjectSoil sciences
dc.subjectBiogeochemistry
dc.subjectEnvironmental science
dc.subject.otherForestry
dc.titleFire, Charcoal, and the Biogeochemistry of Carbon and Nitrogen in Pacific Northwest Forest Soils
dc.typeThesis
dc.embargo.termsOpen Access


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