442 research outputs found

    Plant Community Composition and Structure Monitoring for Agate Fossil Beds National Monument, 2013 Annual Report

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    Introduction During the last century, much of the prairie within the Northern Great Plains has been plowed for cropland, planted with non-natives to maximize livestock production, or otherwise developed, making it one of the most threatened ecosystems in the United States. Within Nebraska, greater than 77% of the area of native mixed-grass prairie has been lost since European settlement (Samson and Knopf 1994). The National Park Service (NPS) plays an important role in preserving and restoring some of the last pieces of intact prairies within its boundaries. The stewardship goal of the NPS is to “preserve ecological integrity and cultural and historical authenticity” (NPS 2012); however, resource managers struggle with the reality that there have been fundamental changes in the disturbance regimes, such as climate, fire, and large ungulate grazing, that have historically maintained prairies, and there is the continual pressure of exotic invasive species. Long-term monitoring in national parks is essential to sound management of prairie landscapes, because it can provide information on environmental quality and condition, benchmarks of ecological integrity, and early warning of declines in ecosystem health. Agate Fossil Beds National Monument (AGFO) was established in 1965 to protect and preserve a large concentration of ancient mammal fossils. The park contains 2, 270 acres of native mixed-grass prairie intersected by riparian vegetation along the Niobrara River. Vegetation monitoring began in AGFO in 1998 by the Heartland Inventory & Monitoring Program (James 2010) and the Northern Great Plains Fire Ecology Program (FireEP; Wienk et al. 2011). In 2010, AGFO was incorporated into the Northern Great Plains Inventory & Monitoring Network (NGPN). At this time, vegetation monitoring protocols and plot locations were shifted to better represent the entire park and to coordinate efforts with the FireEP (Symstad et al. 2012b), and sampling efforts began in 2011 (Ashton et al. 2011). The long-term objectives of the NGPN and FireEP plant community monitoring effort in AGFO are to: 1. Determine park-wide status and long-term trends in vegetation species composition (e.g. exotic vs. native) and structure (e.g. cover, height) of herbaceous and shrub species. 2. Improve our understanding of the effects of external drivers and management actions on plant community species composition and structure by correlating changes in vegetation composition and structure with changes in climate, landscape patterns, atmospheric chemical composition, fire, and invasive plant control. This report is intended to provide a timely release of basic data sets and data summaries from our sampling efforts at AGFO in 2013, our third year of sampling. We visited 6 plots, and it will take 2 more years to visit every plot in the park twice (Figure 1). In addition, we surveyed vegetation in 5 plots that were first installed in 1997 by the Heartland Inventory & Monitoring Network. These plots are concentrated in the southeast corner of the park to evaluate the effects of trail construction (Figure 1). We also sampled vegetation at 11 plots along the riparian corridor at AGFO for the second year in a pilot study to develop a long-term monitoring approach for this area. The riparian corridor is narrow and not adequately represented in our standard sampling, but is of great ecological and management importance to the park. We expect to produce reports with more in-depth data analysis and interpretation when we complete 5 years of sampling. In the interim, reports, spatial data, and data summaries can be provided for park management and interpretation upon request

    Plant Community Composition and Structure Monitoring for Agate Fossil Beds National Monument

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    Agate Fossil Beds National Monument (AGFO) plays a vital role in protecting and managing some of the last remnants of native mixed-grass prairie in the region. The Northern Great Plains Inventory & Monitoring Network (NGPN) and Fire Ecology Program (FireEP) surveyed 12 long-term monitoring plots in Agate Fossil Beds National Monument in 2012 as part of an effort to better understand the condition of plant communities in the park. We measured plant diversity and cover, looked for the presence of exotic species that may be newly invading the park, and evaluated the amount of human and natural disturbance at all plots. This effort was the second year in a multiple-year venture to document the current status and long-term trends in plant communities in AGFO. At the end of five years, there will be an in-depth report describing the status of the plant community. In addition to upland plant monitoring, we also sampled vegetation at 12 sites along the riparian corridor at AGFO as part of a pilot study to develop a long-term monitoring approach for this area. The riparian corridor is narrow and not adequately represented in our standard sampling, but is of great ecological and management importance to the park. In 2013, we will also revisit legacy plots that were established as part of the Prairie Cluster prototype monitoring. In this report, we provide a simple summary of our results from sampling in 2012

    Agate Fossil Beds National Monument Plant Community Composition and Structure Monitoring, 2011 Annual Report

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    Executive Summary The Northern Great Plains Inventory & Monitoring Network (NGPN) was established to develop and provide scientifically credible information on the current status and long-term trends of the composition, structure, and function of ecosystems in thirteen parks located in five northern Great Plains states. NGPN identified upland plant communities, exotic plant early detection, and riparian lowland communities as vital signs that can be used to better understand the condition of terrestrial park ecosystems (Gitzen et al. 2010). Upland and riparian ecosystems are important targets for vegetation monitoring because the status and trends in plant communities provide critical insights into the status and trends of other biotic components within those ecosystems. In 2011, NGPN began plant community monitoring in Agate Fossil Beds National Monument (AGFO). We visited six long-term monitoring plots from June 13-16th, 2011, and recorded a total of 109 vascular plant species. This effort was the first year in a multiple-year venture to understand the status of upland plant communities in AGFO. At the end of five years, there will be an in-depth report describing the status of the plant community. In 2013, we will also revisit legacy plots that were established as part of the Prairie Cluster prototype monitoring. In this report, we provide a simple summary of our results from sampling in 2011. We found the following: • There was considerable variation among plots, but on average bare soil was one-third of ground cover. The absolute vascular plant cover was high due to a wet spring and early summer. Grasses and sedges made up the bulk of vascular plant cover at all sites. • The sites at AGFO had a large diversity of vascular plants. Average native species richness in the 10 m2 plots was 15 ± 2.9 species. Forbs, or broad-leaved herbaceous plants, were more diverse than graminoids, despite making up less of the total cover. • Exotic species occurred in all six plots we visited; however, the relative cover of exotics species was less than 10% across the plots. • The most common disturbance in plots at AGFO was small mammal burrowing, which occurred at four of the six sites

    Agate Fossil Beds National Monument Plant Community Composition and Structure Monitoring

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    The Northern Great Plains Inventory & Monitoring Network (NGPN) was established to develop and provide scientifically credible information on the current status and long-term trends of the composition, structure, and function of ecosystems in thirteen parks located in five northern Great Plains states. NGPN identified upland plant communities, exotic plant early detection, and riparian lowland communities as vital signs that can be used to better understand the condition of terrestrial park ecosystems (Gitzen et al. 2010). Upland and riparian ecosystems are important targets for vegetation monitoring because the status and trends in plant communities provide critical insights into the status and trends of other biotic components within those ecosystems

    Complex coastlines responding to climate change: do shoreline shapes reflect present forcing or “remember” the distant past?

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    A range of planform morphologies emerge along sandy coastlines as a function of offshore wave climate. It has been implicitly assumed that the morphological response time is rapid compared to the timescales of wave climate change, meaning that coastal morphologies simply reflect the extant wave climate. This assumption has been explored by focussing on the response of two distinctive morphological coastlines – flying spits and cuspate capes – to changing wave climates, using a coastline evolution model. Results indicate that antecedent conditions are important in determining the evolution of morphologies, and that sandy coastlines can demonstrate hysteresis behaviour. In particular, antecedent morphology is particularly important in the evolution of flying spits, with characteristic timescales of morphological adjustment on the order of centuries for large spits. Characteristic timescales vary with the square of aspect ratios of capes and spits; for spits, these timescales are an order of magnitude longer than for capes (centuries vs. decades). When wave climates change more slowly than the relevant characteristic timescales, coastlines are able to adjust in a quasi-equilibrium manner. Our results have important implications for the management of sandy coastlines where decisions may be implicitly and incorrectly based on the assumption that present-day coastlines are in equilibrium with current conditions

    Intermetallic Cobalt Indium Nanoparticles as Oxygen Evolution Reaction Precatalyst: A Non-Leaching p-Block Element

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    Merely all transition-metal-based materials reconstruct into similar oxyhydroxides during the electrocatalytic oxygen evolution reaction (OER), severely limiting the options for a tailored OER catalyst design. In such reconstructions, initial constituent p-block elements take a sacrificial role and leach into the electrolyte as oxyanions, thereby losing the ability to tune the catalyst's properties systematically. From a thermodynamic point of view, indium is expected to behave differently and should remain in the solid phase under alkaline OER conditions. However, the structural behavior of transition metal indium phases during the OER remains unexplored. Herein, are synthesized intermetallic cobalt indium (CoIn3) nanoparticles and revealed by in situ X-ray absorption spectroscopy and scanning transmission microscopy that they undergo phase segregation to cobalt oxyhydroxide and indium hydroxide. The obtained cobalt oxyhydroxide outperforms a metallic-cobalt-derived one due to more accessible active sites. The observed phase segregation shows that indium behaves distinctively differently from most p-block elements and remains at the electrode surface, where it can form lasting interfaces with the active metal oxo phases

    Behavior of molecules and molecular ions near a field emitter

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    The cold emission of particles from surfaces under intense electric fields is a process which underpins a variety of applications including atom probe tomography (APT), an analytical microscopy technique with near-atomic spatial resolution. Increasingly relying on fast laser pulsing to trigger the emission, APT experiments often incorporate the detection of molecular ions emitted from the specimen, in particular from covalently or ionically bonded materials. Notably, it has been proposed that neutral molecules can also be emitted during this process. However, this remains a contentious issue. To investigate the validity of this hypothesis, a careful review of the literature is combined with the development of new methods to treat experimental APT data, the modeling of ion trajectories, and the application of density-functional theory simulations to derive molecular ion energetics. It is shown that the direct thermal emission of neutral molecules is extremely unlikely. However, neutrals can still be formed in the course of an APT experiment by dissociation of metastable molecular ions

    Multimessenger parameter inference of gravitational-wave and electromagnetic observations of white dwarf binaries

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    The upcoming Laser Interferometer Space Antenna (LISA) will detect a large gravitational-wave foreground of Galactic white dwarf binaries. These sources are exceptional for their probable detection at electromagnetic wavelengths, some long before LISA flies. Studies in both gravitational and electromagnetic waves will yield strong constraints on system parameters not achievable through measurements of one messenger alone. In this work, we present a Bayesian inference pipeline and simulation suite in which we study potential constraints on binaries in a variety of configurations. We show how using LISA detections and parameter estimation can significantly improve constraints on system parameters when used as a prior for the electromagnetic analyses. We also provide rules of thumb for how current measurements will benefit from LISA measurements in the future.Comment: 8 pages, 5 figures, accepted to MNRA
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