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dc.contributor.advisorChairperson, Graduate Committee: Jean Dixonen
dc.contributor.authorQuinn, Colin Aidanen
dc.coverage.spatialBitterroot Range (Idaho and Mont.)en
dc.date.accessioned2018-12-05T19:24:29Z
dc.date.available2018-12-05T19:24:29Z
dc.date.issued2018en
dc.identifier.urihttps://scholarworks.montana.edu/xmlui/handle/1/14614
dc.description.abstractMountain hillslopes are dynamic settings with discontinuous soils affected by a suite of variables including climate, lithology, hydrology, and vegetation. Our study seeks to understand how forest cover influences soil and rock distribution at decadal to century timescales. We focus on a series of post-glacial hillslopes in Lost Horse Creek of the Bitterroot Mountains, Montana. In this system, avalanche paths maintain parallel, topographically similar swaths of forested and non-forested slopes with uniform aspect, lithology, and climate. We combine field observations, fallout radionuclide analysis (210 Pbex & 137 Cs), and remote sensing data to understand both landscape- and fine-scale patterns in soil and rock distribution. Local soil and rock measurements indicate more extensive soil cover (forest = 94.4 + or = 2.6%; non-forest = 88.3 + or = 1.9%) and thicker soils (6cm greater median) in the forested system. We compare landcover-classified rock to topographic metrics from LiDAR data and find a doubling of rock cover (from 40% to 80%) as hillslope angles transition across slopes of ~24-42 ?. Topographic roughness, calculated as the standard deviation of slope, is predictive of only ~60% of total landscape rock cover, but can identify large boulders and coarse-scale outcrops with higher accuracy (79%). These calibrated remote sensing metrics indicate higher rock cover in non-forested regions (34%, compared to 20% in forested areas), though with high uncertainty. Additionally, we measure fallout-radionuclide inventories in soils to explore variations in decadal transport processes and soil residence times. We find distinct 210 Pb and 137 Cs behaviors in forested and non-forested systems, controlled both by unique partitioning of each nuclide within organic and mineral soil horizons, but also due to depth-driven differences in their physical mobility. Average 210 Pb ex inventories in non-forested soils are 33% lower, and half as variable as soils in the forested region (10.45 + or = 0.97 and 15.49 + or = 1.91 kBq/m 2 respectively), while 137 Cs inventories are indistinguishable (4.04 + or = 0.34 and 3.73 + or = 0.42 kBq/m 2). Together, our spatial, field, and isotope analyses suggest forested systems have greater soil storage and longer residence times than non-forested soils, mediated by differences in surface erosion processes within a larger fire disturbance landscape.en
dc.language.isoenen
dc.publisherMontana State University - Bozeman, College of Letters & Scienceen
dc.subject.lcshSlopes (Soil mechanics).en
dc.subject.lcshTrees.en
dc.subject.lcshErosion.en
dc.subject.lcshIsotopes.en
dc.subject.lcshSoils.en
dc.subject.lcshOptical radar.en
dc.subject.lcshRemote sensing.en
dc.titleSoil storage on steep forested and non-forested mountain hillslopes in the Bitterroot Mountains, Montanaen
dc.typeThesisen
dc.rights.holderCopyright 2018 by Colin Aidan Quinnen
thesis.degree.committeemembersMembers, Graduate Committee: Jean Dixon (chairperson); David McWethy; Stephanie A. Ewing.en
thesis.degree.departmentEarth Sciences.en
thesis.degree.genreThesisen
thesis.degree.nameMSen
thesis.format.extentfirstpage1en
thesis.format.extentlastpage74en
mus.data.thumbpage12en


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