• Feasibility Of Farm-To-School In Alaska: A State-Wide Investigation Of Perspectives From School Food Service Professionals

      Herron, Johanna Ruth; Bersamin, Andrea; Lopez, Ellen; Barry, Ronald; Henry, David (2013)
      Childhood obesity is a significant public health concern and schools are a key setting for prevention. The majority of U.S. children are enrolled in school where they consume a large portion of their daily energy. Farm-to-school programs are a promising strategy for preventing childhood obesity in school-aged children. The overall objective of this study was to conduct a baseline assessment of Alaska school food service professionals' perspectives of using local foods. Specific objectives were to: 1) Assess interest in utilizing local foods, 2) Identify perceived barriers to purchasing local foods, and 3) Determine resources needed to facilitate local food procurement. A survey was administered to all school food service professionals in Alaska (n = 74) who oversee the National School Lunch Program in their program site or district. The survey consisted of open and close-ended questions, comprising six domains: interest, perceived benefits, perceived usefulness, perceived barriers, and future needs. Descriptive statistics were performed on all variables. The majority (80-96%) of school food service professionals reported interest in utilizing local foods in the school meal programs. School food service professional's reported concern with finding a reliable supply (67%) and the cost (46%) of locally sourced foods. Nearly all (92%) school food service professional's agreed that information about what foods are available, where to purchase them, and USDA purchasing regulations would be useful. Farm-to-school strategies are attainable in Alaska. Interest is high, and perceived barriers and challenges are consistent with national findings. The most useful resources identified could be accommodated through increased communication and use of existing resources.
    • Feeding ecology of black oystercatcher (Haematopus bachmani) chicks

      Robinson, Brian H.; Powell, Abby; O'Brien, Diane; Konar, Brenda (2016-05)
      The Black Oystercatcher is an internationally recognized bird species of conservation concern and the focus of multiple monitoring programs due its small global population size, restricted range, vulnerability to human and natural threats in nearshore marine ecosystems, and the important role it plays as a top-level consumer in the intertidal food web. I studied a population of Black Oystercatchers in Kenai Fjords National Park, Alaska in 2013 and 2014, examining variation in chick diet, assessing methods used to monitor diet, and investigating the influence of provisioning on brood survival. To better understand the biases and limitations associated with the quantification of prey remains, I compared diet estimates from prey remains with two other methods: direct observation of adults feeding young, and diet reconstruction by stable isotope analysis. Estimates from collected prey remains over-represented the proportion of limpets in the diet, under-represented the proportion of mussels and barnacles, and failed to detect soft-bodied prey such as worms. I examined age- and habitat-specific variation in chick diet and found no relationship between diet and age of chicks; however, diet differed between gravel beach and rocky island nesting habitats. To determine the importance of diet on brood survival, I modeled daily survival rates of broods as a function of energy intake rate and other ecological factors and found that broods with higher intake rates had higher growth rates and daily survival rates. Given the consequences of reduced energy intake on survival, changes in the abundance and composition of intertidal macroinvertebrates as a result of climate change may have significant impacts on Black Oystercatcher populations. These findings highlight the importance of diet and provisioning to chicks and identify limitations of using prey remains to characterize Black Oystercatcher diet.
    • Feeding ecology of scaup ducklings across a heterogeneous boreal wetland landscape

      DuBour, Adam J.; Lindberg, Mark; Gurney, Kirsty; Hundertmark, Kris (2019-08)
      Understanding how patterns of food resources influence the behavior and fitness of free-living animals is critical in predicting how changes to such resources might influence populations. The boreal region of North America is relatively undeveloped and contains abundant freshwater lakes and wetlands. These largely pristine and stable habitats harbor high densities of aquatic invertebrates, which are a critical food source for the numerous waterbird species that breed in the boreal. Invertebrates are of particular importance for the optimal growth and survival of waterbird chicks. However, observations of long-term change to boreal aquatic habitats and their invertebrate populations associated with a warming climate has been implicated in the declines of some boreal breeding waterbirds, such as the lesser scaup (Aythya affinis). Lesser scaup are known to feed extensively on amphipods, a freshwater crustacean; however, ducklings have been shown to have a diverse diet. Our goal was to use the naturally occurring heterogeneity of aquatic invertebrates across boreal lakes within the Yukon Flats National Wildlife Refuge in interior Alaska to better understand how changes in invertebrate prey resources might affect diet selection and growth in lesser scaup ducklings. First, we used a stable isotope approach to quantify the variation in the trophic niche within our population of ducklings. We found that as a population, lesser scaup ducklings consume a variety of aquatic insects, crustaceans and mollusks, and that variation in the population diet is largely attributable to variation in diet between birds from different lakes with different invertebrate communities. Second, we used the same habitat heterogeneity to examine how gradients of invertebrate abundance relate to the growth of ducklings. We observed that lesser scaup ducklings experienced reduced growth rates in lakes that had little to no amphipods. Taken together, these results suggest that while lesser scaup ducklings are a flexible consumer that can adapt to changes in invertebrate populations, ducklings may face negative fitness repercussions when consuming prey other than amphipods.
    • Fire And Successional Trajectories In Boreal Forest: Implications For Response To A Changing Climate

      Johnstone, Jill Frances; F. Stuart Chapin, III (2003)
      Because of the key role played by fire in structuring boreal forest ecosystems, interactions between vegetation and fire regime may be an important and dynamic control of forest response to climate change. This research uses a series of field observations and experiments in boreal forests to examine the nature of several potential fire and vegetation interactions, and how such interactions may influence forest response to climate change. Long-term observations of post-fire succession provide information on the timing of tree establishment and the effects of early establishment on subsequent successional trajectories. The role of competitive interactions in driving patterns of early establishment was tested with experimental manipulations of aspen (Populus tremuloides) cover after fire. This research demonstrated that competition by aspen re-sprouts may reduce the success of conifer establishment and favor long-term dominance by deciduous trees. The effects of fire severity on successional trajectories were tested in a series of field experiments that contrasted patterns of seedling establishment across differences in depth of the post-fire organic layer. All species in the experiment responded negatively to decreased fire severity, but deciduous trees were more sensitive in their response than conifers. Thus, variations in burn severity are likely to mediate deciduous establishment in organic-rich stands. Observations of natural tree regeneration in stands that burned at different ages also indicate that a decrease in fire interval can influence the relative abundance of deciduous and coniferous species by reducing conifer establishment. Over longer time scales, changes in biota caused by species migration may influence fire and vegetation interactions. Observations of post-fire regeneration at the current distribution limits of lodgepole pine (Pinus contorta) indicate that continued range expansion of pine could initiate rapid shifts in dominance from spruce to pine within a single fire cycle. Together, these results provide insight into the dynamic feedbacks between fire and vegetation that can lead to high levels of system resilience, while also promoting rapid responses when threshold conditions are crossed. A more complete understanding of these interactions will improve our ability to manage and predict boreal ecosystem responses to a changing climate.
    • Fire severity effects on nutrient dynamics and microbial activities In a Siberian larch forest

      Ludwig, Sarah; Ruess, Roger; Kielland, Knut; Alexander, Heather (2016-08)
      High-latitude ecosystems store large amounts of carbon in soil organic matter and are among the most vulnerable to climate change. In particular, fire severity and frequency are increasing in boreal ecosystems, and these events are likely to have direct and indirect effects on climate feedbacks via increased emission of carbon (C) from soil and changes in vegetation composition, respectively. In this study we created experimental burns of three severities in the northeastern Siberian arctic, near Cherskiy, RU, and quantified dissolved C, nitrogen (N), and phosphorus (P), and microbial respiration and extracellular enzyme activities at 1-day, 8-days, and 1-year post-fire. Our objective was to determine how fire affects C, N, and P pools, soil microbial processes, and how these effects scale across severity and time since fire. We found labile C and nutrients increased immediately post-fire, but appeared similar to unburned controls within a week. Phosphorus alone remained elevated through 1-year post-fire. Leucine aminopeptidase activities initially increased with fire severity, but by 1-year, activities decreased with fire severity at a rate an order of magnitude faster. Fire severity suppressed phosphatase and β-glucosidase activities at all time points. Soil respiration was reduced by half in high severity plots 1-year post-fire, while net rates of N mineralization increased by an order of magnitude. We found that changes in soil C and nutrient pools, soil respiration, and net N mineralization rates responded in a threshold-fashion to fire severity, although P was uncoupled from C and N by changing at a distinct severity threshold. Extracellular enzyme activities and edaphic variables scaled linearly with fire severity. The interaction of threshold and linear response curves to fire severity may help explain the variability across studies in soil microbial community responses to fire. Microbial communities recovering from more severe fires have the possibility to decrease future ecosystem C losses through reduced respiration. The changing fire regime in permafrost ecosystems has the potential to alter soil microbial community dynamics, the retention of nutrients, and the stoichiometry of C, N, and P availability.
    • Fire-severity effects on plant-fungal interactions: implications for Alaskan treeline dynamics in a warming climate

      Hewitt, Rebecca E.; Hollingsworth, Teresa; Chapin, F. Stuart III; Rupp, T. Scott; Taylor, D. Lee (2014-08)
      Understanding the complex mechanisms controlling treeline advance or retreat in the Arctic and Subarctic has important implications for projecting ecosystem response to climate change. Changes in landcover due to a treeline biome shift could alter climate feedbacks and ecosystem services such as wildlife and berry habitat. Major sources of uncertainty in predicting treeline advance or retreat are the controls over seedling establishment at treeline and in tundra. One often-overlooked yet physiologically important factor to seedling establishment is the symbiosis with ectomycorrhizal fungi (EMF), the obligate mycobionts of all boreal tree species. EMF provide soil nutrients and water to seedlings and protect against pathogens, enhancing their growth and reducing drought stress. The availability of these critical mycobionts may be limited across the forest-tundra ecotone and by disturbance events such as wildfire. Wildfires are the primary large-scale disturbance in Alaskan boreal forests and are increasingly prevalent in tundra and at treeline. Fire is the major driver of boreal tree seedling recruitment; however, fire also alters the community structure and reduces biomass of EMF, especially after high-severity fires. To investigate the potentially critical role of EMF in seedling establishment at and beyond current treeline in Alaska, I conducted two observational studies and one experimental study that address how fire-severity influences EMF community structure and plant-fungal interactions. These studies indicated that shrubs that survived and resprouted after fires at treeline and in tundra were a source of resilience for EMF diversity and function. Shrubs maintained latesuccessional stage EMF taxa, and the EMF taxa associated with shrubs at treeline were compatible with tree seedlings that naturally established after fire. Many of the EMF taxa that were shared by seedlings and shrubs were present across the low Arctic, suggesting that EMF compatible with boreal tree species are not limited within the predicted geographic range of treeline expansion. Additionally, I found that seedling growth was correlated with post-fire fungal inoculum. Seedling growth was promoted by EMF inoculum provided by resprouting shrubs after fire. However, when fungal inoculum lacked EMF in post-fire tundra soils, seedling biomass was related to the negative effect of soil pathogens and the positive influence of dark septate endophytes. Together these results illustrate the important role of resprouting tundra shrubs as fungal nurse plants for establishment of boreal tree species at and potentially beyond current treeline, and that biotic factors such as EMF-tree interactions are important to seedling performance. My results suggest that the inclusion of biotic effects, like plant-fungal interactions, in simulation models of treeline dynamics will improve the accuracy of predictions of forestation and associated landscape flammability with future warming in Alaska.
    • Foliage and winter woody browse quality of an important Salix browse species: effects of presence of alder-derived nitrogen and winter browsing by Alaskan moose (Alces alces gigas)

      Burrows, Justin; Kielland, Knut; Wagner, Diane; Ruess, Roger (2019-12)
      In this study, I examined the relationship between soil nitrogen and winter browsing by moose on the physical and chemical characteristics of Salix alaxensis; specifically stem production, leaf nutritional quality, and stem nutritional quality of tissues produced the following growing season. I measured stem biomass production the 2013 growing season and offtake during the 2013-2014 winter browsing season at 16 sites on the Tanana River floodplain near Fairbanks, Alaska. I revisited the sites the following summer and autumn to assess regrowth and to collect soil, foliage, and stem samples. Browsing intensity and total soil nitrogen were similar in sites with and without alder, a nitrogen-fixing shrub. Soil nitrogen and browsing intensity were not consistently related to changes in stem or leaf quality, although there were significant relationships in some subsets. Soil nitrogen and browsing intensity also did not have consistent relationships with stem regrowth the following growing season. These results indicate that S. alaxensis growing in this system are able to recover from a naturally broad range of browsing utilization, including very high levels of offtake, and continue to produce nutritious leaves and stems.
    • Foods and foraging ecology of oldsquaws (Clangula hyemalis L.) on the arctic coastal plain of Alaska

      Taylor, Eric John (1986-09)
      The study was conducted from June to September during 1979 and 1980 in the the West Long Lake area of the National Petroleum Reserve-Alaska. Additional oldsquaws were collected in the inland wetlands near the northwest boundary of the reserve at Ice Cape. West Long Lake and the adjacent Goose Lake are located 15 miles south of the Beaufort Sea and immediately west of Teshekpuk Lake.
    • Foraging ecology and conservation biology of African elephants: Ecological and evolutionary perspectives on elephant-woody plant interactions in African landscapes

      Dudley, Joseph Paine; Bryant, John P. (1999)
      The available scientific evidence indicates that African forest elephants and bush elephants are ecologically and evolutionarily distinct taxa. The current practice of regarding these two taxa as ecotypes of a single species, Loxodonta africana (i.e., L. a. africana Blumenbach 1797, L. a. cyclotis Matschie 1900) appears unwarranted, and obscures issues of major significance to the conservation biology of African elephants. Under a proposed taxonomic revision, the African bush elephant retains the designation Loxodonta africana Blumenbach 1797 while the African forest elephant is recognized as Loxodonta cyclotis Noack 1906. The browsing of woody plants by African bush elephants is a major factor in the structural dynamics of semi-arid woodland and scrubland habitats in Hwange National Park (HNP) and the Sengwa Wildlife Research Area (SWRA), Zimbabwe. Drought, frost and fire also influence the structure and species composition of woody vegetation within HNP. Interactions among these three abiotic factors and elephant browsing may have significant impacts on the dynamics of semi-arid woodland and scrubland habitats of HNP. Mortality attributable to elephant damage was identified as a principal cause of death among large trees (>5.0 in height), and a relatively minor but not insignificant cause of death for shrubs and trees in the 1.0--5.0 in height class. The responses of Colophospermum mopane in SWRA to fertilization treatments corresponded to those predicted by the carbon/nutrient hypothesis of plant anti-herbivore defense. Comparisons of these results with those of previous studies suggest possible changes in the ecology and population biology of elephants in HNP during the past decade. Observed differences in the age-specific mortality of elephant in HNP during die-offs in 1993--1995 and 1980--1984 provide independent evidence of changes in the ecology of elephants in HNP during the period 1983--1993. The population of L. a. africana inhabiting the Matabeleland-Ngamiland-Okavango region of southern central Africa (which includes the HNP population), is the largest extant elephant population on Earth. The magnitude of this population (110,000--120,000), and the high proportion of its range currently under protection as wildlife reserves, indicate that this population may rank as the most viable and potentially sustainable elephant population on Earth.
    • Foraging Ecology And Sociality Of Muskoxen In Northwestern Alaska

      Ihl, Claudia; Ruess, Roger; Klein, David (2007)
      I investigated sociality and winter foraging ecology of muskoxen ( Ovibos moschatus) in Cape Krusenstern National Monument, northwestern Alaska. The nutritional value of moss (Hylocomium splendens, Tomenthypnum nitens) for muskoxen was evaluated by incubating moss in rumen-fistulated muskoxen and simulating post-ruminal digestion by incubation in acid-pepsin. Moss was indigestible in muskoxen and gained mass and nitrogen in the rumen. Consequently, high moss consumption during winter may result in net loss of nitrogen from a muskoxen's system. Local and regional differences in moss use by muskoxen and caribou or reindeer (Rangifer tarandus) were investigated in northwestern Alaska in relation to indicators of winter range quality. On muskox winter ranges, increases in fecal moss indicated decreased graminoid cover, harder snow, increased moss cover, and greater animal densities. Higher mobility of caribou than muskoxen during winter limits use of their feces to reflect local forage selection, but fecal moss may indicate caribou winter range quality on a larger, regional scale. Increasing proportions of moss in muskoxen feces may alert wildlife managers to shifts in forage availability due to changing snow conditions. Roles of male and female muskoxen in coordinating group movements were investigated during the snow-free season. Adult females led most activity initiations, foraging-bout movements, and spontaneous group movements. Rutting males actively manipulated female-led movements through herding and blocking. Leaders incurred no costs in terms of lost foraging time. Habitat use by muskoxen shifted from upland habitats in early summer towards lowland sedge meadows during rut. Muskox group sizes decreased from winter to summer to rut. Muskoxen foraging efficiency decreased with group size in spatially unlimited but not in spatially limited habitats. Adult males contributed least to group cohesion, and their presence may contribute to group fission during rut. A conceptual model is presented which discusses how habitat, foraging, social behavior, and predation threat contribute to group sizes, fission and fusion of muskox groups. Results from this study indicate that winter ranges used by muskoxen in Cape Krusenstern may be limiting, which suggests that numbers of muskoxen in this area will likely remain small. Therefore, hunting quotas should be low and limited to males only.
    • Foraging ecology of yellow-rumped warblers in an Alaskan boreal forest following a spruce beetle outbreak

      Bartecchi Rozell, Kristen (2004-12)
      I examined the foraging ecology of the Yellow-rumped Warbler (Dendroica coronata) several years after an outbreak of spruce beetles (Dendroctonus rufipennis) in the Copper River Basin, Alaska. With increased beetle-induced mortality of white spruce (Picea glauca), a preferred foraging substrate, we predicted warblers would respond through: (1) decreased overall use of white spruce, (2) increased selectivity of live white spruce that remained, and (3) reduced foraging efficiency, reflected by a greater proportion of time spent foraging and lower prey attack rates. We examined warbler foraging behavior and arthropod biomass on commonly used foraging substrates, and in stands with low-moderate (<40%) and heavy (>40%) spruce mortality. Live and dead white spruce, quaking aspen, and willow were the most commonly used foraging substrates, and selection of coniferous versus deciduous tree types varied by breeding stage. Yellow-rumped Warblers foraged extensively on dead spruce in stands with heavy spruce mortality, although they avoided it in stands with low-moderate spruce mortality. Dead spruce supported significantly lower arthropod biomass than any other tree type except black spruce, and warblers that foraged in dead spruce tended to have lower prey attack rates than when they foraged in live white spruce.
    • Forest Ecology And Distribution Of Bats In Alaska

      Parker, Doreen Ingrid; Cook, Joseph A.; Klein, David R.; Rexstad, Eric A. (1996)
      This thesis documents distribution of bat species in Alaska and effects of clearcutting on bat activity in temperate rainforests of southeastern Alaska. Occurrence of Myotis lucifugus, M. californicus, M. volans, M. keenii, and Lasionycteris noctivagans is confirmed in southeastern Alaska. I describe new specimens of M. keenii from southeastern Alaska, the first in over 100 years. Myotis lucifugus and Eptesicus fuscus are documented north of 64$\sp\circ$ N latitude. Environmental conditions and geography which influence distribution and latitudinal diversity gradients are discussed. Low bat activity in second-growth forests and clearcuts suggests that these areas provide little summer habitat. Higher activity levels in old-growth and riparian forests suggest these areas are important summer habitat. A change in activity between lactation and post-lactation periods is also noted. Unusual aspects of M. lucifugus ecology in southeastern Alaska are: consumption of spiders; presence of maternity colonies in a temperate rainforest; and intermittent use of hibernacula. <p>
    • Formation and optical properties of photochromic silver nanoparticles

      Lee, George Patrick (2005-05)
      Spherical silver nanoparticles may be produced by the reduction of Ag (aq) by borohydride in the presences of citrate. When (phenylphosphinidene) bis-(benzenesulfonic acid) is also present, and the reaction mixture is illuminated, nonspherical Ag nanoparticles are formed. We have discovered that the shape of some Ag nanoparticles can be repeatedly changed by subjecting them to numerous cycles of light and dark. To our knowledge, this has never been reported in the literature. These photo chromic Ag nanoparticles displayed at least two different particle shapes: prismatic and spherical. The difference in morphology could be determined by the color of the solution and by the electronic spectra. The prismatic Ag nanoparticles can be photochemically synthesized in 24hrs and then converted into a spherical form by placing them in the dark for 14hrs. This transformation is accompanied by a blue shift in the visible spectrum. The prismatic particles are reformed by placing them in the light for 4 hrs. This transformation has a red shift in the visible spectrum.
    • Formation of solar prominences and eruption of solar magnetic arcade systems

      Choe, Gwang-Son; Lee, Lou-Chuang; Akasofu, Syun-Ichi; Roederer, Juan G.; Swift, Daniel W.; Watkins, Brenton J. (1995)
      Formation and eruption of solar prominences, coronal mass ejections (CMEs) and solar flares are the most magnificent phenomena among solar activities. Observations show that there is an interrelationship among these events and that their manifestation is conditioned by certain common photospheric signatures. One of them is the increase in magnetic shear. In this thesis, the evolution of the solar atmosphere is studied by numerical simulations with photospheric motions as boundary conditions. Firstly, mechanisms of prominence formation are investigated. It is found that prominences can be formed by the development of a thermal instability (1) in a rapidly expanding magnetic arcade, (2) in a magnetic island created by magnetic reconnection or (3) in the current sheet between two bipolar arcades. Secondly, the quasi-static evolution of a magnetic arcade subject to footpoint shearing is studied under the ideal MHD condition. Three distinct evolutionary phases are found, in the last of which a current layer develops and grows indefinitely with the increasing shear. Force-free field solutions are also constructed and compared with dynamic solutions. Finally, resistive evolutions of magnetic arcades are investigated imposing resistivity on the pre-sheared magnetic fields. It is found that there is a critical amount of shear, over which magnetic reconnection can take place to create a magnetic island. The effects of different values and spatial patterns of resistivity are studied. With a localized resistivity, most of principal features in solar eruptive processes are reproduced. A comparative study is made between the numerical results and observations.
    • Foxes and food subsidies: anthropogenic food use by red and Arctic foxes, and effects on Arctic fox survival, on the Arctic Coastal Plain of Alaska

      Savory, Garrett; O'Brien, Diane; Hunter, Christine; Hueffer, Karsten; Person, Brian (2013-12)
      Food subsidies have the potential to impact wildlife on the Arctic Coastal Plain of Alaska. Red foxes (Vulpes vulpes (L., 1758)) expanded their range into Arctic regions during the 20th century, and the availability of anthropogenic foods may have contributed to their success and persistence in the Arctic. Arctic foxes (Vulpes lagopus (L., 1758)) are also known to forage on anthropogenic foods in Prudhoe Bay and to forage on marine mammals on the sea ice, but it is unknown whether these strategies benefit survival of Arctic foxes. This thesis examined: 1) the importance of anthropogenic foods to the diets of red and Arctic foxes in Prudhoe Bay, and 2) the factors with the greatest effect on Arctic fox survival, including access to food subsidies in Prudhoe Bay and on the sea ice. For the first study, stable isotopes of red and Arctic fox tissues were used to infer late summer, late winter, and lifetime (for red fox only) diets. The contribution of anthropogenic foods to the diets of both species was low in late summer (~10%) but high in late winter (49%, 95% credible interval = 38-57%, of red fox diets and 37%, 95% credible interval = 29-44%, of Arctic fox diets). Estimates of lifetime diet in red foxes revealed high levels of anthropogenic food use, similar to the winter diet. To characterize the extent of competition for food resources, dietary niche overlap was examined between both species by comparing isotopic niche space. Both fox species had little isotopic niche overlap but may have greater overlap between their ecological dietary niches. Availability and consumption of anthropogenic foods by red foxes, particularly in winter, may partially explain their year-round presence in Prudhoe Bay. For the second study, nest survival models and satellite collar data were used to evaluate whether multiple factors affected survival of adult and juvenile foxes. Site and sea ice use had two times more support than the other factors. Three groups of foxes were identified based on capture location and sea ice use, which corresponded to different survival rates: Prudhoe Bay foxes, NPR-A foxes that used sea ice during more than eight 2-week periods during the winter (seven 2-week periods for juveniles), and NPR-A foxes that did not use sea ice. Both adult and juvenile foxes at Prudhoe Bay had modestly higher annual survival rates, 0.50 (90% CI 0.31-0.69) and 0.04 (90% CI 0.0-0.08) respectively, than foxes at NPR-A that did not use sea ice, 0.40 (90% CI 0.18-0.62) and 0.01 (90% CI 0.0-0.04) respectively. NPR-A foxes that used sea ice extensively had the highest survival rates. Food subsidies may have far-reaching effects on red and arctic foxes on the Arctic Coastal Plain of Alaska.
    • Fracture characteristics and distribution in exposed cretaceous rocks near the Umiat anticline, North Slope of Alaska

      Wentz, Raelene; Hanks, Catherine; McCarthy, Paul; Wallace, Wesley (2014-08)
      Umiat oil field in the southeast part of the National Petroleum Reserve-Alaska is a shallow, thrust-related anticline in the northern foothills of the Brooks Range and was one of the earliest discovered oil fields on the North Slope of Alaska. Despite significant reserves of light oil, Umiat has remained undeveloped because the reservoirs are located at shallow depths within the permafrost. Recent development of horizontal drilling techniques could provide access to this shallow reservoir with a minimal surface footprint, and has caused industry to take a second look at Umiat. Fracture networks are valuable in petroleum systems because they can enhance both porosity and permeability in a reservoir and they act as migration pathways from source rocks to reservoir. At Umiat, natural fractures, if open, could enhance reservoir permeability or, if filled with cement or ice, could impede fluid flow. In order to determine the potential of fractures at Umiat, I examined core from older Umiat wells and surveyed fractures at four exposed anticlines similar to Umiat anticline. Three fracture sets were observed in the surface anticlines: an early north-south set of calcite-filled regional extension fractures that predate folding and are interpreted as due to elevated pore pressures during burial and under north-south compression; east-west oriented, unfilled hinge-parallel extension fractures that formed during folding due to outer arc tangential longitudinal strain in fold hinges; and a set of unfilled, vertical conjugate shear fractures oriented perpendicular to fold hinges that is interpreted as having developed on the fold limbs. Several natural fractures were identified in unoriented core from Umiat wells. These natural fractures dip steeply with respect to bedding and are calcite cemented and/or open. Lack of orientation data precludes assigning these fractures directly to a fracture set observed in surface exposures, but the presence of, calcite cement suggest that these fractures belong to the early, north-south oriented calcite-filled fracture set seen in nearby surface exposures. These observations suggest that production in horizontal legs could vary depending on the azimuth of the borehole. North-south, calcite-filled fractures could serve as permeability baffles and reduce flow in north-south oriented legs. Alternatively, horizontal legs that encounter the open hinge-parallel fractures or hinge perpendicular conjugate set could experience early water breakthrough or loss of circulation.
    • Fractured reservoir potential and tectonic development of the Iniskin -- Tuxedni region, Lower Cook Inlet, Alaska

      Rosenthal, Jacob L.; Nadin, Elisabeth; Prakash, Anupma; Betka, Paul; Gillis, Robert (2016-12)
      Fracture patterns can provide insight into the strain history and stress evolution of deformed strata. In southern Alaska's Cook Inlet forearc basin, hydrocarbon traps are typically fault-cored anticlines, where fractures likely aid in the migration of hydrocarbons from lower Jurassic marine strata into Cenozoic non-marine deposits. Consequently, understanding the distribution and orientation of fracture sets with respect to these structures is necessary to improving the understanding of one of Alaska's largest petroleum provinces. Furthermore, recent refinements in understanding southern Alaska's Dynamic Cenozoic tectonic evolution allow us to interpret fractures in a regional tectonic context. Despite the important role fractures likely play in the Cook Inlet petroleum system, limited work exists linking fractures to regional tectonic events and structures. The objective of chapter one is to characterize from field and remote sensing observations the orientations, distributions, and relative ages of several regionally prominent fracture sets. Field observations focus on the area of the western Cook Inlet near Augustine Volcano, north to Tuxedni Bay. Remote sensing observations expand the study area from the Alaska Peninsula in the south to Mount Spurr in the north. I identified four fracture sets—with common orientations, opening modes, and relative ages—within the sedimentary sequence that spans early Jurassic to Miocene time in the Cook Inlet forearc basin. Within the field area, these sets fall into two structural domains: 1) the Iniskin Peninsula, site of an anticline--syncline pair and reverse slip on the SW-striking Bruin Bay fault; and 2) north of Chinitna Bay, where the Bruin Bay fault strikes ~N--S and preserves primarily sinistral displacement. Chapter two is aimed at quantifying the fracture intensity of the four regional fracture sets defined in Chapter 1, which are pervasive in deformed forearc basin strata of Jurassic age in the Iniskin--Tuxedni region of the lower Cook Inlet, Alaska. I document how fracture intensity changes between the four regionally identified fracture sets of chapter one. Analysis of fracture intensity indicates that changes in fracture intensity are guided by the opening of other fractures and grain size. I also measured fractures at the thin-section scale, via back-scattered electron microscopy, to test the feasibility of using micro fracture analysis to estimate macro fracture abundance. I conclude by discussing how natural fractures could enhance sub-surface permeability for the lower Cook Inlet hydrocarbon province; and serve as migration pathways in the lower and upper Cook Inlet petroleum systems.
    • Freshwater Fish Biogeography In The Bering Glacier Region, Alaska

      Weigner, Heidi L.; Hippel, Frank von; Hundertmark, Kris; Lopez, Andres; Pfeiffer, David (2012)
      Bering Glacier, Alaska, is Earth's largest surging glacier, with surges occurring approximately every 20-30 years since 1900. Surges and subsequent retreats lead to a dynamic environment for aquatic communities, as glacial ice over-rides landscapes and new habitats form during glacial retreat. Lands around Bering Glacier are administered by the State of Alaska and the U.S. Bureau of Land Management (BLM). Purposes of this study are to characterize fish communities and provide information relevant to their management for BLM. Given Bering Glacier's remoteness, little information exists regarding its fish communities. Fish were collected over five summer field seasons (2002-2006), with 10 fish species collected in 80 lakes and streams. Results indicate that Dolly Varden (Salvelinus malma), threespine stickleback ( Gasterosteus aculeatus), prickly sculpin (Coitus asper), and coho salmon (Oncorhynchus kisutch) are first to colonize new habitat after glacial retreat. Ten locations with sympatric populations of anadromous and resident freshwater threespine stickleback were found. Geometric morphometrics and genetic analyses were conducted on these species pairs to test hypotheses regarding their formation. Possible origins include sympatric speciation, double invasion of anadromous fish, and independent colonization by resident freshwater fish from pre-existing lakes and streams along with anadromous fish. Body shape analyses of anadromous vs. resident freshwater stickleback supported the independent colonization hypothesis, because of a lack of body shape co-variation between groups, a lack of correlation of geometric morphometric variables with site age, and few fish with intermediate body shape at each site. Origin hypotheses were tested by use of the frequency of the Euro-North American Clade (ENAC) vs. the Trans North Pacific Clade (TNPC) in the mtDNA as well as sequence divergence of a portion of the mtDNA gene NADH2. A greater proportion of TNPC fish exist in resident freshwater populations at all sites, supporting the independent colonization hypothesis. The NADH2 sequence data did not help to clarify the origins. Future research at Bering Glacier should examine broader scale sequence divergence in genomes of stickleback and other colonizing fishes to advance the understanding of contemporary evolution and management implications in this newly formed aquatic landscape.
    • From a snowflake to the snow cover: processes that shape polar and taiga snowpacks

      Filhol, Simon; Sturm, Matthew; Truffer, Martin; Larsen, Christopher F.; Eicken, Hajo (2016-08)
      Snowpacks found in boreal and polar regions are the most widespread types of snow in the world, covering up to 14% of the globe. In both regions, snow accumulates over a long period (6-7 months), transforming the landscape by the presence of a thin snowpack (≤70 cm), affecting the local climate, ecology, and hydrology. In the case of polar snow, wind plays a crucial role in redistributing snow, and shaping the snow surface. But in the case of the taiga snow found in the forests of the boreal regions, micro-topography and vegetation are stronger drivers of snow distribution than wind. In this dissertation, I explore the mechanisms responsible for shaping the snow surfaces in windy and in calm conditions. Collecting data at the plot scale with a terrestrial lidar, I sought explanations of the features geometry visible on the snow surfaces in grain scale physical processes. Because snow is close to its fusion temperature in this environment, its behavior at the grain scale can greatly influence its bulk properties. So finding linkages between processes occurring at the grain scale and the observable features at the plot scale may be key to furthering our understanding of snow distribution. In the first study, I found that the morphology and the occurrence of the seven known types of snow bedforms are dependent on the ability for wind to erode the surface. Erodibility is directly linked to the sintering of wind-slab grains. For this reason, every snow dune eventually turns into sastrugi. In the second study, I studied the effects of underlying topography on the accumulation of snow in calm conditions. I found that processes such as bouncing, cohesion or interlocking of snowflakes can either enhance or inhibit the smoothing of initial bumps. In the third study, I found that plant canopies affect the deposition of snow in the boreal forest. I could differentiate up to five types of canopies for their effects on snow accumulation. Despite the complexity of the canopy structures we observed, over three years, similar accumulation patterns and reactions of canopies to snow loading were seen. I was surprised to find the presence of subnivean cavities associated to plants with a size equivalent to the average snow depth.
    • From Forest To Tundra: Historical Biogeography, Floristic Diversity And Nucleotide Variation In Balsam Poplar

      Breen, Amy L.; Olson, Matthew; Murray, David F.; Taylor, D. Lee; Walker, Donald A.; Wolf, Diana E. (2010)
      The North America boreal forest extends across more than 10� of latitude from central Labrador to interior Alaska. Periods of major climate fluctuations, including glacial and interglacial cycles, drove major migrations in the Quaternary history of the boreal forest. Beringia, the unglaciated region between the Lena and Mackenzie rivers, is recognized as an important refugium for arctic plants during the last ice age, but its role for boreal trees remains controversial. The paleobotanical record indicates Populus balsamifera (balsam poplar) survived within Beringia during the last glacial. My research employed an interdisciplinary approach, combining techniques in the fields of ecology, evolution and population genetics, to reconstruct the late Quaternary migration history of balsam poplar and to describe and classify balsam poplar plant communities in the Alaskan Arctic. Chapter 1 describes the motivation for the research. Chapter 2 addresses whether a demographically-detectable population of balsam poplar was present within Beringia during the most recent ice age. I found that patterns of variation in chloroplast DNA are most consistent with the presence of a single population of balsam poplar south of the continental ice sheets through the Late Quaternary. Chapter 3 is an analysis of floristic diversity in balsam poplar communities across the Arctic Slope, Interior Alaska and the Yukon Territory and asks whether one balsam poplar-associated plant community spans the arctic and boreal regions, or if these communities differ. I found that arctic communities are dominated by arctic-alpine taxa, whereas boreal communities are dominated by boreal taxa. A strong linkage between climate and the occurrence of balsam poplar also was observed on the Arctic Slope. Chapter 4 is a study of nucleotide diversity in three nuclear loci across the range of balsam poplar. This was the first study to document geographic structure in genetic variation within the species. It also showed that diversity in three North American poplars (P. balsamifera, P. deltoides and P. trichocarpa) was substantially less than that of three Eurasian poplars (P. alba, P. nigra and P. tremula). Chapter 5 summarizes the research and points toward future research directions.