30 research outputs found

    Updated glacial chronology of the South Fork Hoh River valley, Olympic Peninsula, Washington through detailed stratigraphy and OSL dating

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    Four glacial advances are preserved and exposed in the stratigraphy of the South Fork Hoh River valley. The oldest of these advances extended beyond the South Fork valley into the Hoh River valley. The three younger advances are preserved in the stratigraphy cut bank exposures in the valley and geomorphically by moraines and outwash plains. One of these advances represents a re-advance to the same terminal position of the previous advance and has not previously been recognized in this valley or other glaciated valleys in the western Olympic Mountains. This finding advocates for a detailed sedimentologic and stratigraphic approach to glacial deposits and questions whether a similar advance is seen in other glaciated valleys of the region. If so, this may reveal information regarding climate influences on glacial advance not previously considered for this specific time period

    Developmental Failure and Loss of Reproductive Capacity as a Factor in Extinction: A Nine-Year Study of Dedeckera Eurekensis (Polygonaceae)

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    Many long-lived perennial species exhibit lowered reproductive capacity. Early studies of reproductive success in Dedeckera eurekensis (Polygonaceae) demonstrated that the species exhibited extremely low reproductive success, low seed/ovule (S/O) ratios (i.e., the percentage of ovules that produce filled seeds; 2.5 %), low germinability of filled seeds (3.5%), low seedling survivorship (11 .1%), and lack of recruitment in natural populations. These results were attributed to genetic load, but this elicited controversy, prompting long-term studies of the relationship between the S/O ratio and environment. After nine years of monitoring, however, the S/O ratio had not changed significantly (2 .7%), and there was no significant correlation between precipitation and the S/O ratio. Controlled field experiments demonstrated that neither resource availability nor other ecological factors significantly influenced embryo abortion rates. Controlled self-pollinations (N = 115) matured only one questionably filled seed, whereas intrapopulation cross-pollinations (N = 192) produced significantly more seed (S/O = 12.0 %). Previous pollination studies demonstrated that the species has no primary pollinators and is only rarely visited by a few generalist insects. However, the flowers typically self-pollinate in 2—3 days following anthesis. Strong inference suggests that the loss of reproductive capacity in D. eurekensis may be the result of inbreeding depression due to the superimposition of self-pollination on a normally outcrossed species carrying a high genetic/segregational load

    Fire and Ice in Central Idaho: Modern and Holocene Fires, Debris Flows, and Climate in the Payette River Basin, and Quaternary and Glacial Geology in the Sawtooth Mountains

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    This 2-day trip will highlight recent fire and storm-related debris flows in the Payette River region, Holocene records of fires and fire-related sedimentation events preserved in alluvial fan stratigraphic sequences, and geomorphology and geology of alpine glaciations in the spectacular Sawtooth Mountains and Stanley Basin of central Idaho. Storm events and associated scour following recent fires in the South Fork Payette basin have exposed Holocene fire-related debris-flow deposits, flood sediments, and other alluvial fan-building deposits that yield insights into Holocene environmental change. Moraine characteristics and sediment cores from the southeastern Sawtooth Mountains and Stanley Basin provide evidence of late Pleistocene alpine glaciation. A combination of these glacial records with reconstructions of regional equilibrium line elevations produces late-glacial paleoclimatic inferences for the area. Day one of the trip will examine recent and Holocene fire-related deposits along the South Fork Payette River; day two will focus on alpine glaciation in the Sawtooth Mountains (fig. 1). A description of the scope, methods, results and interpretation of the South Fork Payette fire study is given below. Background information on late Pleistocene alpine glaciation in the eastern Sawtooth Mountains is presented with the material for day 2 of the trip. The road log for day 1 of the trip begins at Banks, Idaho, and ends in Stanley, Idaho. Stop locations are shown on figure 2. At Stop 1, we will provide an introduction to interpretation of alluvial fan stratigraphic sections, and discuss the Boise Ridge fault. At Stops 2–4 (Hopkins Creek, Deadwood River, and Jughead creek), we will examine recent debrisflow deposits and Holocene alluvial fan stratigraphic sections. At Stop 5 (Helende Campground), we will look at a series of well-preserved Holocene and Pleistocene terraces and at Stop 6 (Canyon Creek), we will briefly inspect fire-related deposits in higher-elevation alluvial fan stratigraphic sections. The road log for day 2 begins at Stanley, Idaho, and ends in Sun Valley, Idaho. Stop locations are shown on figure 2. Stop 1, at Redfish Lake, will focus on regional equilibrium line altitude reconstructions and on the general pattern of late Pleistocene glaciation on the eastern flank of the Sawtooth Mountains. Stop 2 will be at Pettit Lake, where we will examine the moraine sequence and discuss relative weathering criteria and moraine groupings. At Stop 3, near Alturas Lake, we will discuss lake sediment coring, moraine chronology, and implications for latest Pleistocene paleoclimatic inferences. Stop 4 will be a brief stop at Galena Summit for an overview of the Sawtooth Mountains and a discussion of ice accumulation patterns. The trip will end at a set of moraines in the Trail Creek valley, near Sun Valley, where we will examine moraine morphology and weathering rind data that constrain the moraine ages

    Crop Updates 2002 - Geraldton

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    This session covers twenty seven papers from different authors: 1. Taking the Why out of Wyalkatchem – the new widely adapted wheat variety, Steve Penny Jr, Department of Agriculture 2. Future wheat varieties, Robin Wilson, Iain Barclay,Robyn McLean, Robert Loughman, Jenny Garlinge, Bill Lambe, Neil Venn and Peter Clarke Department of Agriculture 3. Maximising wheat variety performance through agronomic management, Wal Anderson, Raffaele Del Cima, James Bee, Darshan Sharma, Sheena Lyon, Melaine Kupsch, Mohammad Amjad, Pam Burgess, Veronika Reck, Brenda Shackley, Ray Tugwell, Bindi Webb and Steve Penny Jr Department of Agriculture 4. Cereal rust update 2002 – a new stem rust on Camm wheat, Robert Loughman1and Robert Park2 1Department of Agriculture, 2University of Sydney 5. Influence of nutrition and environmental factors on seed vigour in wheat, Darshan Sharma, Wal Anderson and Daya Patabendige, Department of Agriculture 6. Cereal aphids and direct feeding damage to cereals, Phil Michael, Department of Agriculture 7. A decision support system for control of aphids and BYDV in cereal crops, Debbie Thackray, Jenny Hawkes and Roger Jones, Department of Agriculture and Centre for Legumes in Mediterranean Agriculture 8. Summary of 2001 weather and seasonal prospects for 2002, David Stephens, Department of Agriculture 9. Towards a management package for grain protein in lupins, Bob French, Senior Research Officer, Department of Agriculture 10. Lupin genotypes respond differently to potash, Bob French and Laurie Wahlsten, Senior Research Officer and Technical Officer, Department of Agriculture 11. Time of harvest for improved seed yield of pulses, G. Riethmuller and B. French, Department of Agriculture 12. Comparing the phosphorus requirement of field pea and wheat, M. Bolland and P. White, Department of Agriculture Western Australia 13. Field pea variety evaluation, T. Khan, Department of Agriculture Western Australia 14. Diamondback moth (DBM) in canola, Kevin Walden, Department of Agriculture 15. WA blackleg resistance ratings on canola varieties for 2002, Ravjit Khangura, Martin J. Barbetti and Graham Walton, Department of Agriculture 16. The effect of single or multiple spray treatments on the control of Diamondback moth (Plutella xylostella) and yield of canola at Wongan Hills, Françoise Berlandier, Paul Carmody and Christiaan Valentine, Department of Agriculture 17. Perennial pastures in annual cropping systems: Lucerne and beyond, Roy Latta and Keith Devenish, Department of Agriculture 18. Nutrition in 2002: Decisions to be made as a result of last season, Bill Bowden,Department of Agriculture 19. Profitability of deep banding lime, Michael O\u27Connell, Chris Gazey and David Gartner, Department of Agriculture 20. Economic comparisons of farming systems for the medium rainfall northern sandplain, Caroline Peek and David Rogers, Department of Agriculture 21. The use of Twist Fungus as a biosecurity measure against Annual Ryegrass Toxicity (ARGT), Greg Shea, GrainGuard Coordinator and George Yan, Biological and Resource Technology 22. Major outcomes from IWM demonstration sites, Alexandra Douglas, Department of Agriculture 23. Understanding the weed seed bank life of important agricultural weeds, Sally Peltzer and Paul Matson, Department of Agriculture 24. Seeding rate, row spacing and herbicides for weed control, David Minkey, Department of Agriculture 25. Improving weed control in grazed pastures using legumes with low palatability, Clinton Revell and Giles Glasson, Department of Agriculture, Dean Thomas, Faculty of Agriculture, University of Western Australia 26. Group F resistant wild radish: What’s new? Aik Cheam1, Siew Lee1and Mike Clarke2, 1Department of Agriculture WA, 2Aventis Crop Science 27. Knockdown herbicides do not reliably kill small grass weeds, Peter Newman and Glenn Adam, Department of Agricultur

    Response of Glacier to Climate Change in Grand Teton National Park, Wyoming

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    This study evaluates recent ice area changes of the small, remote glaciers in Grand Teton National Park, Wyoming. Findings for the Teton Glaciers include shrinking ice masses in or after warmer and drier years. This study uses map and photographic data analysis (remote sensing), field mapping, and analysis of meteorological data. Sources of remote sensing data include United States Geological Survey topographic maps, QuickBird imagery, and aerial photos. To calibrate remote sensing data, at least two representative glaciers were studied in the field. Field work recorded glacier geometry and added to the ground-based photo record. Meteorological data collected by nearby National Weather Service Cooperative Observer Program stations are used to compare ice area change to regional records of temperature and precipitation. Preliminary data indicate that the Schoolroom Glacier experienced a maximum of 23% increase in ice area between 1994 and 2001. The glacier then decreased by a maximum of 16% in area from 2001 to 2006. Imagery of all Teton Range glaciers in 2009 showed substantial cover of snow on ice, rendering ice margins difficult to determine during the late summer end of the ablation season. Climate records offer some insight to these ice area changes. Between 1994 and 2001, mean annual temperatures recorded in Moose, WY varied within 1°C while the annual sum of precipitation varied between 30 and 82 cm. During this time period, the ice area increased. Between 2001 and 2006, the mean annual temperature varied within 2°C and the annual sum of precipitation increased by 22 cm. During this time period, the area of ice margins decreased. The storage of water in glaciers at river headwaters affects regional river flows. In turn, the status of the Teton glaciers characterize the quality of hydrologic, ecologic, and aesthetic resources of the Park and surrounding region

    Glacial forest refugium in Howard Valley, South Island, New Zealand

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    Fossils of forest habitat beetles and leaves of Nothofagus menziesii provide evidence of a forest refugium at times between ca. 34 000 and ca. 18 500 cal. a BP at an upland site in Howard Valley, located adjacent to glaciated valleys in South Island, New Zealand. The stratigraphy of the glacial-aged terrace sequence of organic-rich silts and fluvial sand/gravels indicates that soil development occurred episodically for around 15 000 a. Fifty-four beetle taxa represent seven habitat types: forest, forest or scrub, riparian and aquatic, litter, grass/tussock, marshland and moss habitats. Leaf and beetle fossils indicate that forest dominated by N. menziesii persisted at the site for most of the time period represented, and tree line taxa such as Taenarthrus sp. 1 (Carabidae) and Podocarpus sp. (Podocarpaceae) indicate that the site may represent the upper tree limit for full-glacial time. The finding of forest at this elevated site adds to the growing fossil evidence for multiple forest refugia in New Zealand during the last glaciation and is consistent with the pollen records, which have consistently indicated the presence of forest species during the last glaciations

    Stephen C. Porter, 1934–2015

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    Multiple Glacial Advances in the Rangitata Valley, South Island, New Zealand, Imply Roles for Southern Hemisphere Westerlies and Summer Insolation in MIS 3 Glacial Advances

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    Stratigraphic evidence and extensive optically stimulated luminescence (OSL) geochronology from an 18-km-long reach of the middle Rangitata Valley, South Island, New Zealand, provide evidence for at least six distinct glacial advances during the last glacial cycle. These include four well-constrained Marine Oxygen Isotope Stage (MIS) 3 and 2 advances at ca. 38 ka, ca. 27 ka, ca. 21 ka and at 18 ka, as well as less well-constrained advances in MIS 4 and/or early MIS 3. Ice occupied a farther downvalley reach of the Rangitata from 38 ka to after 18 ka, indicating that near-full glacial conditions persisted for most of the last 20 ka of the last glaciation, though the glacier still fluctuated significantly, as reflected by the numerous distinguishable advances. Global or regional cooling alone cannot explain the persistence of near-maximum glacial conditions for this extended period, nor can it explain the occurrence of the largest advances ca. 32 ka. Instead, we invoke the northward expansion of the westerlies during MIS 3 as the cause for the early widespread glaciation, wherein enhanced westerly flow under moderate cooling maximised glacial extents. Local insolation favoured extended MIS 3 glaciation until ca. 32 ka. Increasing summer insolation gradually reduced glacial extents after ca. 28 ka
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