Browsing by Author "Pastor, John"

Now showing 1 - 10 of 10
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    Airborne Imaging Scanner Survey of Northeastern Minnesota
    (University of Minnesota Duluth, 1990-04) Hauck, Steven A; Ager, Cathy; Pastor, John; Zanko, Lawrence M; Aaseng, N
    An airborne imaging scanner survey was flown over two areas in the Duluth Complex and one area along the Vermilion fault zone on September 12, 1988 to detect heavy metal induced stress in plants due to the presence of buried mineral deposits. The Duluth Complex flight lines covered copper-nickel and iron-titanium mineral deposits while the Vermilion fault flight line covered Archean gold mineralization sites. The 63 channel imaging scanner had a spatial resolution of about 9-10 meters and a flight path width of approximately 6.4-7.2 kilometers along three flight lines. Supervised, unsupervised, principal components and inverted principal components analysis and Chebyshev polynomial expansions were used on data collected over two test sites, i.e., the east end of the Archean flight line and the Dunka Pit area, to learn whether or not vegetative stress could be identified in areas with known metallic mineralization. Interpretation of the Dunka Pit test site was abandoned because: 1) the test site was too small; 2) much of the canopy was dead; and 3) the test site was overwhelmed by an adjacent, highly reflective mine dump. At the Archean site, ground spectroradiometer data was collected to assist with the interpretation of the imaging scanner data. The ground data indicated spectral shifts to both longer and shorter wavelengths in vegetation over mineralized compared with unmineralized sites. However, the imaging scanner data did not indicate any evidence of vegetative stress in mineralized areas. At this point, the imaging scanner survey data are useful mainly for discriminating different types of vegetation.
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    "The Biogeochemical Habitat of Wild Rice" (2014-09-16)
    (2014) Pastor, John; Johnson, Nathan; Craig, Timothy P
    “The Biogeochemical Habitat of Wild Rice” by John Pastor, Ph.D., Professor, UMD Biology and Nathan Johnson, Ph.D, UMD Civil Engineering
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    Factors Controlling the Recovery of Aquatic Systems from Disturbance
    (University of Minnesota Duluth, 1988-08) Niemi, Gerald J; Naiman, Robert J; Pastor, John
    The enclosed report represents a summary of a two year effort to develop an approach for assessing the recovery of aquatic systems from disturbance. The report is divided into three sections: ( 1) a general overview of the results of an extensive search of the scientific literature for case studies on recovery of aquatic systems, (2) an extensive compilation of the raw data for case studies in which some aspect of the recovery of an aquatic system has been documented, and (3) a list of references for each of the case studies on recovery. Hence, this report summarizes case studies of recovery and what will be the necessary steps to develop a comprehensive useable approach to predicting recovery rates of organisms within aquatic systems.
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    Iron Sulfide Formation on the Root Surfaces of Wild Rice
    (2017-08-16) LaFond-Hudson, Sophia; Johnson, Nathan; Pastor, John; Dewey, Brad; lafo0062@d.umn.edu; LaFond-Hudson, Sophia
    The data are from an experiment showing life-cycle induced iron sulfide formation on root surfaces of wild rice. Plants with and without added sulfate were harvested during the reproductive stage of the life cycle to quantify concentrations of iron and sulfide on root surfaces. Seed and plant N was measured to examine the effect of iron sulfide root plaques on seed production. On amended roots, iron transitioned from mostly Fe(III) to mostly Fe(II) as sulfide concentrations increased rapidly. Amended plants produced fewer, lighter seeds with less nitrogen.
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    MASTODONS (Mammut americanum) AND THE LATE-GLACIAL VEGETATION OF THE EASTERN USA
    (Geological Society of America, 2018-11) Drazan, Jacqueline L; Mooers, Howard D; Moen, Ron; Pastor, John; Larson, Phillip C; Swartz, Jennifer A; David, Mady K; Bopray, Croix K; Jaksa, Michael P; Messer, Blake S
    Numerous studies of tooth plaques and remains of gut contents of have confirmed that mastodon diet was composed of woody browse species, forbs, nuts, and fruits. However, fossil gut contents also suggest that mastodon diet included significant amounts of spruce, even though spruce is a low-quality, chemically-defended food. Most extant large mammals only browse on spruce when all other food sources are exhausted, and mastodon tusk growth increments indicate that mastodons were not food limited as they moved toward extinction (Fisher, 2009). Here we review the vegetation associated with mastodon habitat from the Great Lakes to the Gulf Coast, USA, over the period 18-10 ka cal BP using pollen assemblage data from 29 sites located near proboscidean fossil remains. Pollen data were acquired from the Neotoma Database and pollen abundance was converted into species biomass abundance using the Landscape Reconstruction Algorithm (LRA) of Sugita (2004a, 2004b). Although spruce was the dominant conifer throughout the Great Lakes Region until ca. 10 ka cal BP, deciduous species such as ash, oak, and elm comprised 50% or more of the vegetation assemblages even at the earliest and northernmost sites, and remained at similar levels until mastodon extinction. Many of these species have been found in mastodon gut contents. These vegetation assemblage reconstructions support the suggestion that mastodons were not food limited as they neared extinction. Moreover, these analyses of landscapes surrounding mastodon sites strongly suggest that the contemporaneous forest, composed of large amounts of spruce intermixed with ash, elm, and oak, was unlike the forests found in much of eastern North America today.
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    The North Woods: Past, Present, and Future (2016-04-01)
    (2016) Pastor, John; University of Minnesota Duluth. Department of Biology
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    Patch formation and maintenance in an old-growth hemlock-hardwood forest
    (1993) Frelich, Lee E.; Calcote, Randy R.; Davis, Margaret B.; Pastor, John
    Cause of patch formation was investigated on a 7.2 ha study area in Sylvania Wilderness Area, a primary forest remnant in Upper Michigan comprising a mosaic of hemlock, sugar maple, and mixed-forest patches. Spatial autocorrelation analysis of the stem map indicated that, although most species pairs have a neutral association between canopy trees and understory trees of other species, hemlock and sugar maple canopy trees both have strong positive self association and negative reciprocal association with each other. No species pairs have a positive reciprocal association on regeneration with each other. MOSAIC, a Markov simulation model in which transition probabilities depend on neighborhood species composition, shows that the negative reciprocal association between hemlock and sugar maple of the intensity observed in this study, could lead to spatial separation into monodominant patches over long time periods (3000 yr). The mixed-forest patches are along spatial continua of varying steepness between sugar maple and hemlock patches. Interactions sugar maple and hemlock overstory and understory trees, along with the pattern of invasion of hemlock, provide a reasonable explanation for the patch structure. Pedological, topographical, and disturbance history differences do not coincide with the location of patches within upland forests on the study area.
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    Supporting data for "Sulfur geochemistry impacts population oscillations of wild rice (Zizania palustris)"
    (2020-07-10) LaFond-Hudson, Sophia; Johnson, Nathan W; Pastor, John; Dewey, Brad; lafo0062@d.umn.edu; LaFond-Hudson, Sophia
    Wild rice populations decline with exposure to elevated sulfate due to production of sulfide in anoxic sediment. Using self-sustaining wild rice mesocosms, we collected data on the population response to sulfate, as well as iron and litter, which both may modify the production and availability of sulfide to plants. Wild rice also experiences natural population oscillations due to delays in release of nitrogen from decomposing litter. We use this data to investigate how sulfate-induced population declines interact with stable litter-driven population cycles. Population data was collected 2014-2019, and geochemical data (iron, sulfide, pH) was collected in 2019, after 5 years of of a factorial design treatment (sulfate, iron, litter).
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    Think Pieces on UMD's Liberal Education Program and the Value of the Liberal Arts
    (2019-12-04) Hylenski, Kristen; Brady, Jennifer; De Souza, Rebecca; Bauerkemper, Joseph; Gore, David Charles; Shanks, Samuel; Pastor, John; Caprioli, Mary; Pine, Adam; Minor, Elizabeth; Twu, Krista Sue-Lo; Lindaman, Dana; Beard, David; Syring, David; Maclin, Rich; Gran, Rik
    A collection of brief essays on the role of a liberal education and/or the Liberal Arts for undergraduate students penned by UMD faculty
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    Wild rice geochemistry and reproductive life stage data from experimental pots amended with sulfate, 2016
    (2019-10-24) LaFond-Hudson, Sophia L; Johnson, Nathan W; Pastor, John; Dewey, Brad; lafo0062@d.umn.edu; LaFond-Hudson, Sophia L
    Wild rice, an annual aquatic plant produces fewer, smaller seeds with less nitrogen when exposed to sulfide, but does not produce decreased vegetative biomass. We compared the timing and duration of reproductive life stages in sulfate-amended plants to unamended plants to see how sulfide affects reproductive phenology. We recorded the life stage of plants starting with initiation of reproduction until senescence and measured seed count, mass and nitrogen content. Additionally, we sampled the geochemistry of porewater, sediment, and root surfaces to understand how plant life stage may control sediment redox conditions relevant to sulfide.