• The geology of three extrusive bodies in central Alaska Range

      Albanese, Mary; Turner, Don; Swanson, Samuel; Gilbert, Wyatt; Kienle, Juergen; Stone, David (1980-05)
      The Buzzard Creek basalt, Jumbo Dome, and Sugar Loaf Mountain occur in the Central Alaska Range. The purpose of this study is to determine the age, nature, geothermal potential, and possible genetic relationships between these igneous bodies. The areas were investigated by mapping, radiometric dating, and petrologic studies. The Buzzard Creek basalt appears to have formed by a maar eruption about 3,000 years ago. Seismic evidence suggests this basalt may be related to current subduction in the area. Jumbo Dome consists of calc-alkaline andesite and is probably Pleistocene in age. Sugar Loaf Mountain is composed of Mid-Tertiary rhyolite. Geochemistry suggests that the Sugar Loaf Mountain rhyolite and Jumbo Dome andesite may also be subduction-related. Differences in age and geochemistry indicate there is no genetic relationship between the rocks of the three areas. The ages, type of volcanic features', and snow melt patterns suggest that these three areas have low geothermal potential.
    • Suprathermal electron tails in a beam-plasma instability

      Hollerbach, Uwe; Swift, W.; Stenbaek-Nielsen, H. C.; Rees, M. H.; Kan, J. R. (1987-09)
      This study investigated the suprathermal electron tails produced in a beam-plasma instability, and their scaling with beam and background densities. A periodic one-dimensional electrostatic simulation was used to study the suprathermal tails. Electrons were treated as particles, and ions were treated as a fluid. The simulation showed that ion dynamics are required for the formation of the suprathermal tails, as expected from the theory of the oscillating two-stream instability. The energy of the suprathermal tails is directly proportional to the beam density, and does not depend strongly on the background density. There is a slight decrease in the energy of the suprathermal tails as the background density increases. A novel numerical effect was also found: a three-plasmon interaction caused by the modification of the Langmuir wave dispersion relation when high-order splines are used as particle shape factors.
    • An anomalous process of fast ionization of a barium shaped charge release

      Xin, Wei; Swift, D. W.; Smith, R. W.; Kan, J. R. (1987-12)
      Fast ionization in excess of the photo-ionization rate appears to only occur when the barium shaped charge release is along the magnetic field direction. This thesis investigates the hypothesis that rapid ionization is caused by electrons heated in an ion cyclotron wave excited by the field-aligned streaming of barium ions through the ambient ionospheric plasma. The seed population of barium ions is assumed to be due to photo-ionization. The number density of barium ions due to photo-ionization is calculated. The plasma dispersion relation is derived based on the assumption of collisionless plasma. The excitation of barium ion cyclotron waves due to the interpenetrating of barium ions through the ambient plasma is investigated. It is proposed that the electrons are heated by the Doppler shifted waves via Landau damping. The Doppler shift is caused by an ambipolar electric field generated by the finite divergence of the injected barium neutrals.
    • Characterization of muskox habitat in northeastern Alaska

      O'Brien, Constance Marsha (1988-12)
      In northeastern Alaska, muskoxen have been most often found in riparian habitats and proximate uplands. Vegetation was studied in nine adjacent river drainages; six of the drainages are regularly used by muskoxen. Twenty-two vegetation/land cover types were described using aerial photographs, point-intercept sampling, and ocular cover estimates. The proportion of each cover type was estimated for each drainage and compared among drainages by MANOVA. There was no significant difference among non-muskox drainages in the average proportion of cover types. A marginally significant difference was found among muskox drainages. There were no significant differences in the proportions of each vegetation type in non-muskox drainages versus muskox drainages. Five vegetation types associated with high forage quality and availability and low snow accumulation were often used by muskoxen. Four of these five vegetation types typically had <7% cover in the nine drainages and are critical habitat components in northeastern Alaska.
    • Cytogenetics and sex determination in collared lemmings

      Jarrell, Gordon Hamilton; Shields, Gerald F. (1989)
      Collared lemmings (Dicrostonyx groenlandicus rubricatus) from northeastern Alaska were found to have sex chromosomes that differ from those of their Siberian congeners, because of fusion to a particular pair of autosomes. But, as in Siberian lemmings, breeding experiments showed that sex determination involves an X-linked "male-repressor," which causes carriers to develop as fertile females, despite the presence of a Y chromosome. Genotypic frequencies in offspring are consistent with Mendelian expectations of such a system, hence natal sex ratios normally favor females. X-linkage of the male-repressor in Siberia and in Alaska indicates that the gene is probably located on the "original" arms of the X chromosome rather than on the fused autosomal arms, which differ on the two continents. One consequence of the autosomal fusion to the sex chromosomes is that deleterious recessive alleles on the autosome fused to the X chromosome are more resistant to selection than at truly autosomal loci. Another consequence is that, because males are heterozygous for loci fused to the sex chromosomes, they are more resistant to inbreeding depression than XX females. One inbred line produced a natal sex ratio of 67% males. The male-bias probably resulted from loss of the male-repressor and from a lethal carried on the formerly autosomal arm of the X chromosome. As inbreeding coefficients approached 0.3, the lethal would have been homozygous in half of the homogametic (female) zygotes. This phenomenon may explain the excess of males and XY females observed in earlier work. Also, if under the natural mating system, inbreeding depression limits fitness, then fusions of autosomal chromatin to the heterochromosomes could be an adaptation to reduce inbreeding depression in heterogametic individuals. Some other genetic features of collared lemmings do suggest endogamy. Female-biased sex ratios can evolve when mating occurs between neighboring individuals who are more related than if mating occurred randomly. Two proposed sources of such "viscous" gene flow in lemmings are cyclical changes in population density and mosaic habitat. Alternatively, could climate may favor winter aggregation and inhibit the dispersal of winter-born offspring, which would mature and mate with close relatives; dispersal and outbreeding would occur in summer. Thus, inbreeding would be seasonal rather than density-dependent and it is unnecessary to suppose discontinuous habitat.
    • Electrostatic ion cyclotron waves in barium injection experiments in space

      Kangas, Kim A.; Swift, D. W.; Stenbaek-Nielsen, H. C.; Kan, J. R. (1989-05)
      Electrostatic ion cyclotron waves are investigated in a charge-generated barium-shaped plasma directed parallel to the earth’s magnetic field. The barium plasma is generated as a result of a barium shape charge release in the upper F₂ region of the ionosphere undergoing photoionization, Using a differential velocity distribution given by Stenbaek-Nielsen et al., [1984], this situation has been modeled based on the condition of collisionless plasma. The instabilities were studied for cases with and without an ambient oxygen ion background. It was concluded that fast ionization in excess of photoionization due to the excitation of electrons by electrostatic ion cyclotron waves was not feasible for the ejection directed along the earth’s magnetic field nor would there be any contribution to Alfven’s critical velocity mechanism if the injection was directed perpendicular to the magnetic field.
    • A simulation study of magnetic reconnection processes at the dayside magnetopause

      Shi, Yong; Lee, L. C.; Akasofu, S-I.; Gatterdam, R.; Gosink, J.; Swift, D. W. (1989-12)
      In this thesis, the day side reconnection processes are studied by using computer simulations. First, the global magnetic reconnection patterns at the dayside magnetopause are studied based on a two-dimensional incompressible magnetohydrodynamic (MHD) code. It is found that multiple X line reconnection may prevail at the dayside magnetopause when the magnetic Reynolds number is large (> 200). The formation and subsequent poleward convection of magnetic islands are observed in the simulation. The Alfvén Mach number of the solar wind, MAsw , cam also change the reconnection patterns. For a large reconnection tends to occur at the higher latitude region. Secondly, the structure of the dayside reconnection layer is studied by a two-dimensional compressible MHD simulation. In a highly asymmetric configuration typical of the dayside magnetopause, the pair of slow shocks bounding the reconnection layer in Petschek’s symmetric model is found to be replaced by an intermediate shock on the magnetosheath side and a weak slow shock on the magnetospheric side. In addition, a mechanism for the enhancement of By, which is observed in the magnetopause current layer and magnetic flux tubes, is proposed.
    • Lichen Availability on the Range of an Expanding Caribou (Rangifer tarandus) Population in Alaska

      Fleischman, Steven J.; Klein, David R.; Thompson, Steven K.; Viereck, Leslie A.; White, Robert G.; Regelin, Wayne L. (1990-05)
      Terrestrial lichen abundance, lichen availability as affected by snow, and winter fecal composition were investigated for the Delta Caribou Herd (DCH), which recently quadrupled in size and expanded its early winter range. Mean lichen abundance was relatively low (10-85 g/m2). However, even on heavily-used range, caribou ate only 7% of lichen standing crop annually. Snow affected lichen availability only slightly on peripheral tundra ranges, since lichens predominated on xeric sites with little snow. On traditional ranges, lichens were shorter and rarely found in high-density patches; disproportionate grazing and trampling of exposed lichens had caused reduced lichen availability. This was reflected in lower fecal lichen for caribou on traditional ranges, however DCH population growth or seasonal movements probably were not substantially affected. A model of caribou cratering energetics indicated that loss of potential foraging time may influence energy balance more than does cratering energy expenditure.
    • Effects of milk intake, growth and suckling effieciency on suckling behavior of muskox (Ovibos moschatus) calves

      Tiplady, Barbara Ann (1990-12)
      General theory on parental provisioning predicts that mammalian offspring receiving more milk should show longer suckling bouts, greater total suckling time, longer intervals between bouts, and greater suckling success. For muskoxen I found that suckling bout duration and suckling success were positively correlated with milk intake during some but not all stages of lactation. Neither interval between suckling bouts, nor total suckling time, was correlated with milk intake. Growth of calves was positively related to milk intake, and among calves of the same age suckling efficiency (intake/min suckling) was highly related to body weight. Therefore, milk intake affects growth rate, which in turn affects suckling efficiency. The overriding influence of calf body size and suckling efficiency limits interpretation of differences in suckling behavior that can be attributed to milk intake by muskox calves and therefore to the provisioning strategy of the cow.
    • Spatial scales of muskox resource selection in late winter

      Wilson, Kenneth J. (1992-05)
      I examined resource selection by muskoxen in late winter on the coastal plain of the Arctic National Wildlife Refuge, Alaska, by comparing use and availability at regional, meso, local, and micro spatial scales. Use of vegetation types for feeding appears to be based on selection of areas of shallow soft snow with high cover of sedges, dead vegetation, and total vegetation, and on selection against areas of little vegetation cover or deep hardpacked snow. Muskoxen used moist sedge, tussock sedge, and Dryas terrace tundra in proportion to availability and avoided barren ground, partially vegetated, riparian shrub, and Dryas ridge tundra. Selection for areas of shallow snow occurred within vegetation types as well as between vegetation types. Occurrence of sedges and grasses in the diet was greater than availability. Feeding zones were primarily on windblown vegetated bluffs; these areas are distributed in narrow bands along creeks, rivers, and the coastline.
    • Comparative patterns of winter habitat use by muskoxen and caribou in northern Alaska

      Biddlecomb, Mark Edward (1992-09)
      Snow depth and hardness strongly influenced selection of feeding zones, (i.e., those areas used for foraging), in late winter by both muskoxen (Ovibos moschatus) and caribou (Rangifer tarandus grand) in northern Alaska. Snow in feeding zones was shallower and softer than in surrounding zones. Depth of feeding craters was less than the average snow depth in feeding zones. Moist sedge tundra types were used most often by muskoxen, and their diet, based on microhistological analysis of feces, was dominated by graminoids. Moist sedge and Dryas tundra types were most often used by caribou; lichens and evergreen shrubs were the major constituents of their diet. Despite selection of moist sedge tundra types by both muskoxen and caribou in late winter, dietary and spatial overlap was minimal.
    • Winter forage selection by barren-ground caribou: effects of fire and snow

      Saperstein, Lisa Beth (1993-05)
      Snow depth and hardness were the most influential factors in selection of feeding areas by caribou (Rangifer tarandus) in late winter in northwestern Alaska. Following a 1988 fire, plots were established in late March through April in burned and unbumed tussock tundra in 1990 and 1991. Snow in both burned and unbumed plots was shallower and softer at edges of caribou feeding craters than at adjacent undisturbed points in both years. There was little difference in snow depth or hardness between burned and unbumed plots, although caribou cratered in shallower snow in burned plots than in unbumed plots in 1990. Crater area was greater in unbumed plots in 1990, but there was no difference in crater area between burned and unbumed plots in 1991. Frequencies of particular plant taxa were only significant in determining selection of crater sites in unbumed plots in 1990, when caribou craters had higher relative frequencies of lichens and lower frequencies of bryophytes than unused areas. Fire reduced relative frequency and biomass of most plant taxa, with the exception of post-disturbance species, which occurred primarily in burned plots. Lichens were reduced in burned plots, and lichens composed 59-74% of the late-winter diet of caribou, as determined by microhistological analysis of fecal pellets. Biomass and relative frequency of Eriophorum vaginatum was greater in burned plots than in unbumed plots in 1991, and protein and in vitro digestibility levels were enhanced in samples of this species collected from burned plots in late winter.
    • Nesting ecology of ducks in interior Alaska

      Petrula, Michael J. (1994-09)
      This study represents one of the first intensive efforts to locate and monitor duck nests in interior Alaska. We located 263, 409 and 450 nests of 12 duck species on Minto Flats in 1989, 1990 and 1991,respectively. We conclude that habitat for breeding waterfowl cannot be considered stable in interior Alaska. Flooding reduced the availability of meadows which precluded ducks from nesting in high-water years despite their presence during the Breeding Pair Survey. Differences in the length of the breeding season and differential response to photoperiod between sub-Arctic and prairie nesting ducks suggest the potential for genetic differences between populations. Similar clutch sizes between high and mid-latitudes, however, suggest that ducks are able to compensate for the additional energetic costs associated with breeding at high latitudes. Flooding of meadow habitat and low nest success resulting from predation probably limit overall duck production on Minto Flats.
    • Black bear denning ecology and habitat selection in interior Alaska

      Smith, Martin E.; Follmann, Erich; Dean, Fred; Hechtel, John; Bowyer, Terry (1994-12)
      To identify conflicts between existing black bear (Ursus americanus) management and human activity on Tanana River Flats, Alaska, we monitored 27 radio-collared black bears from 1988-1991. We compared denning chronology, den characteristics, den-site selection, and habitat selection across sex, age, and female reproductive classes. Mean den entry was 1 October and emergence was 21 April, with females denned earlier and emerging later than males. Marshland and heath meadow habitats were avoided, and willow-alder was selected for den-sites. Eighty-three percent of dens were excavated, 100% contained nests, 18% were previously used, and 29% had flooded. Black bears selected black spruce-tamarack and birch-aspen significantly more, and marshland and heath meadow significantly less than available. Marshland and birch-aspen were used significantly more in spring than autumn. Marshland was used less than available by all bears in all seasons. Special habitat or den-site requirements are not critical for management of Tanana River Flats black bears.
    • Home range, habitat selection, and movements of lynx (Lynx canadensis) in eastern interior Alaska

      Perham, Craig J.; Follmann, Erich H.; Rextad, Eric A.; Cook, Joseph; Jenkins, K. (1995-12)
      Lynx home ranges, habitat selection, and daily track deposition rates were determined in interior Alaska. Male home ranges averaged 167 km2 in 1991-92 and 127 km2 in 1992-93, but varied (14-270 km2); females averaged 33 km2 in 1991-92 and 48 km2 in 1992-93. Nomadic lynx displayed erratic movements and large ranges, whereas others dispersed from the study area. Lynx with small home ranges may use snowshoe hare refugia whereas other lynx may range over expanded areas to acquire food. Lynx preferred broadleaf and mixed forests and avoided dwarf shrub/tundra. Lynx used a 1959 burn more than expected; more recent burns (<11 years) were used less than expected. Track deposition was significantly related to snowfall, temperature and barometric pressure change (P< 0.001), the overall model, however, explained only 16% of the variation in deposition (R2 = 0.162). Temperature was most related to track deposition; as temperature increased, track deposition became more variable.
    • The subglacial hydraulics of the surge-type Black Rapids Glacier, Alaska: a schematic model

      Cochran, Oakley D.; Harrison, William; Weeks, Wilford; Kane, Douglas; Echelmeyer, Keith; Benson, Carl (1995-12)
      The subglacial hydraulic system of the surge-type Black Rapids Glacier was studied in 1993 by comparing glacier velocity and seismicity with the stage, electrical conductivity, and turbidity of its proglacial streams. Brief events of increased velocity and seismicity occurred at the beginning and end of the measurement season. Five events coincided with drainages of supraglacial lakes and potholes. During events, water was stored englacially or subglacially and released subsequently, as indicated by a dye tracing experiment. Conductivity-stage-seismicity relationships suggest a model wherein daily storage and release of water depended on variations in subglacial pressure, which were reflected by daily variations in seismicity. Heavy precipitation and increases in stage preceded late-season pothole drainages. We hypothesize that precipitation triggered pothole drainages by enlarging drainage conduits, thus lowering subglacial pressure. Differences between the drainage systems in 1993 and 1986-89 may reflect mechanisms of surge evolution.
    • Survival and brood rearing ecology of emperor geese

      Schmutz, Joel A.; Sedinger, James; Rexstad, Eric; Ruess, Roger; Scwaegerle, Kent (2000-12)
      Emperor Geese (Chen canagica) breed on the Yukon-Kuskokwim Delta in an area inhabited by three other goose species. Whereas populations of other geese increased since the mid 1980s, Emperor Goose numbers remained low. Because survival and habitat selection by broods of Emeperor Geese had not been studied previously and numbers of predatory Glaucous Gulls (Larus hyperboreus) had recently increased, I studied brood rearing ecology of Emperor Geese during 1993-1996 to assess whether this seasonal period could be limiting population growth. Survival of goslings to 30 days varied among years from 0.32 to 0.70 and was primarily influenced by mortality during the first five days after hatch. Other goose species with similar rates of gosling survival are increasing rapidly. Survival of Emperor Goose goslings was lowest in 1994, when unusually heavy rainfall occurred during early brood rearing. Using a long-term data set from Izembek National Wildlife Refuge, sizes of families in fall (n=23 years) were related to rainfall during early brood rearing. Gosling survival was lower and gull disturbance of broods greater in 1993-1994 than in 1995-1996. Although goslings wer commonly consumed by Glaucous Gulls, gull diets during 1993 were similar to those observed in the 1970s. Across a broad scale, broods of Emperor Geese (n=56) strongly selected habitats dominated by Carex subspathaceae, Carex ramenskii, and unvegetated areas interspersed among these forage species, as determined from telemetry. These selected habitats comprised one-third of all available habitat. Habitat selection by the composite goose community (dominated by Cackling Canada Geese [Branta canadensis minima]) was assessed by feces collections and differed substantially from that of Emperor Geese. Broods of Emperor Geese spent more time feeding during 1993-1996 than during an earlier study in 1985-1986. During 1994-1996, feeding rates of gosling and adult females was related more to total goose density than to Emperor Goose density. Although Cackling Canada Geese exhibited strongest selection of other habitats, their greater overall abundance resulted in numerical equivalence to Emperor Geese in habitats preferred by Emperor Geese. Interspecific competition for food has impacted behavior in Emperor Geese, which may impact growth and survival of juvenile geese.
    • Effects of migratory geese on plant communities and nitrogen dynamics in an Alaskan salt marsh

      Zacheis, Amy Beach; Ruess, Roger; Hupp, Jerry; Schwaegerle, Kent; Sedinger, James (2000-12)
      Herbivory is an integral component of ecosystems that impacts plant communities and ecosystem processes, and affects forage availability and quality for the herbivore. I investigated the effects of lesser snow geese (Anser caerulescens caerulescens) and Canada geese (Branta canadensis) on two salt marsh communities, a sedge meadow and an herb meadow, in Cook Inlet, Alaska. Geese used the marshes during spring migration for a brief period, and foraging intensity was low compared to other goose-grazing systems. Seventy percent of the snow goose diet was on belowground plant tissues, whereas 92% of the Canada goose diet was on aboveground shoots. In the sedge meadow, where feeding was primarily on aboveground shoots, there was no effect of grazing on biomass of the dominant species Carex ramenskii and Triglochin maritimum, or on shoot nitrogen concentrations in these species (an index of forage quality). An experiment with captive geese found no effect of herbivory on biomass or nitrogen concentrations at foraging intensity ten times greater than that imposed by wild geese, indicating that this community is highly resilient to herbivory. In the herb meadow, where snow geese fed on belowground tissues, biomass of Plantago maritima and Potentilla egedii was lower, and biomass of Carex ramenskii higher, on grazed compared to ungrazed plots. Plant species' response to herbivory was determined by plant growth form, the type of herbivory (above- or belowground), and competitive interactions. Light herbivore pressure in this community altered the relative abundance of forage species for geese. In the sedge meadow community, geese increased nitrogen mineralization rates by trampling litter into wet soils. Litter incorporated into soils increased organic nitrogren pool size, decreased soil C:N ratios, and facilitated the growth of nitrogen-fixing cyanobacteria, all of which led to increased mineralization rates in grazed areas. Fecal nitrogren inputs were small and did not affect nitrogen availability. A captive goose experiment found that fecal additions ten-fold larger also had no effect on nitrogen availability. In the herb meadow, geese did not affect nitrogen mineralization because soils were dry with little standing water, so that incorporation of litter into soils through trampling was less important.
    • Phytochemistry and chemosystematics of Artemisia arctica in Alaska

      Riggins, Chance W.; Clausen, Thomas; Stoltzberg, Richard; Schwaegerle, Kent (2001-05)
      Artemisia L. (Asteraceae - Anthemideae) is a large and taxonomically complex genus occurring widely throughout the northern hemisphere. Chemical investigations in this genus have mainly been stimulated by the economic and/or medicinal importance of many of its members. This chemical knowledge has also provided useful criteria for resolving systematic uncertainties within the genus. Alaskan Artemisia species are little known chemically despite their historic and contemporary medicinal use. Therefore, an investigation of the chemistry of Alaskan Artemisia arctica was initiated with the dual purpose of searching for structurally novel and/or biologically active compounds and contributing additional criteria for systematic studies of this taxon. Collections of A. arctica from four different geographic locations in Alaska were analyzed for chemical characters and biological activity. The roots and leaves afforded one novel acetylenic isocoumarin, in addition to several known acetylenic and non-acetylenic compounds. The biological and systematic significance of these results are discussed.
    • Assessment of total mercury and methyl mercury in selected subsistence fish in Western Alaska

      Zhang, Xiaoming; Duffy, Lawrence K.; Kelly, John J.; Naidu, Satyanarayan (2001-08)
      Total Hg (THg) and methylmercury (MeHg) were examined in muscle and liver samples of salmon species (Chinook: Oncorhynchus tshawytscha; Chum: O. keta; Sockeye: O. nerka; Coho: O. kisutch) and freshwater fish species (Pike: Esox lucius; Grayling: Thymallus arcticus; Whitefish: Caregonus nelsoni) collected in 1999 and 2000 from the Western Alaska rivers (Yukon, Kuskokwim, Nushagak and Kvichak). The THg in salmon muscles has a mean value of 62 ng/g (ww). In Pike muscles, THg has a mean value of 879 ng/g. The mean concentrations of THg in Grayling and Whitefish muscle are 153 ng/g and 32 ng/g respectively. In salmon muscle and liver the MeHg levels constitute 77% and 62% of the THg levels, respectively. In Pike muscle the MeHg levels constitute 100% of the THg levels. A significant correlation between Hg levels and fish length was found. Calculated consumption limits indicate that children may consume 0.05-1.5 kg of fish per month, depending on the species consumed. The study suggests that, from 1979 to 1998, nearly 21 kg of MeHg was transported by Sockeye salmon to the Alaskan rivers of the Bering Sea east coast.