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41.
Abstract

Natural resource challenges often span administrative jurisdictions and include actors and processes operating at different spatial and political scales. We applied concepts of new environmental governance to analyze Oregon’s approach to greater sage-grouse conservation. Through one in-depth case study in Lake County, we traced features of new environmental governance (cross-scale interactions, decentralization, and capacities of actors) through different governance levels. Interviews and qualitative analysis revealed that decentralization of administrative functions facilitated cross-scale interactions and relied on intermediaries, gap-filling, and perceptions of legitimacy at lower levels. State and agency guidelines steered the effort and were accompanied by financial and technical resources from multiple arenas, which increased local capacity. This study adds to the understandings of environmental governance for implementing multi-actor, multi-level conservation arrangements in resource-dependent communities. Further exploration of connections between higher levels and local contexts will reveal important, new ways to link policies with on-the-ground outcomes.  相似文献   
42.
Elevated turbidity (Tn) and suspended sediment concentrations (SSC) during and following flood events can degrade water supply quality and aquatic ecosystem integrity. Streams draining glacially conditioned mountainous terrain, such as those in the Catskill Mountains of New York State, are particularly susceptible to high levels of Tn and SSC sourced from erosional contact with glacial-related sediment. This study forwards a novel approach to evaluate the effectiveness of stream restoration best management practices (BMPs) meant to reduce stream Tn and SSC, and demonstrates the approach within the Stony Clove sub-basin of the Catskills, a water supply source for New York City. The proposed approach is designed to isolate BMP effects from natural trends in Tn and SSC caused by trends in discharge and shifts in average Tn or SSC per unit discharge (Q) following large flood events. We develop Dynamic Linear Models (DLMs) to quantify how Tn-Q and SSC-Q relationships change over time at monitoring stations upstream and downstream of BMPs within the Stony Clove and in three other sub-basins without BMPs, providing observational evidence of BMP effectiveness. A process-based model, the River Erosion Model, is then developed to simulate natural, hydrology-driven SSC-Q dynamics in the Stony Clove sub-basin (absent of BMP effects). We use DLMs to compare the modelled and observed SSC-Q dynamics and isolate the influence of the BMPs. Results suggest that observed reductions in SSC and Tn in the Stony Clove sub-basin have been driven by a combination of declining streamflow and the installed BMPs, confirming the utility of the BMPs for the monitored hydrologic conditions.  相似文献   
43.
Current understanding of bedform dynamics is largely based on field and laboratory observations of bedforms in steady flow environments. There are relatively few investigations of bedforms in flows dominated by unsteadiness associated with rapidly changing flows or tides. As a consequence, the ability to predict bedform response to variable flow is rudimentary. Using high‐resolution multibeam bathymetric data, this study explores the dynamics of a dune field developed by tidally modulated, fluvially dominated flow in the Fraser River Estuary, British Columbia, Canada. The dunes were dominantly low lee angle features characteristic of large, deep river channels. Data were collected over a field ca 1·0 km long and 0·5 km wide through a complete diurnal tidal cycle during the rising limb of the hydrograph immediately prior to peak freshet, yielding the most comprehensive characterization of low‐angle dunes ever reported. The data show that bedform height and lee angle slope respond to variable flow by declining as the tide ebbs, then increasing as the tide rises and the flow velocities decrease. Bedform lengths do not appear to respond to the changes in velocity caused by the tides. Changes in the bedform height and lee angle have a counterclockwise hysteresis with mean flow velocity, indicating that changes in the bedform geometry lag changes in the flow. The data reveal that lee angle slope responds directly to suspended sediment concentration, supporting previous speculation that low‐angle dune morphology is maintained by erosion of the dune stoss and crest at high flow, and deposition of that material in the dune trough.  相似文献   
44.
The eastern oyster, Crassostrea virginica, is a prominent ecosystem engineer, whose reefs exhibit strikingly consistent morphologies at multiple spatial scales throughout its North American range. These distinct morphologies are thought to form by interactions of nascent reef structures with hydrodynamics. We carried out two field studies to determine if historical reef configurations applied in a restoration context would improve reef persistence and restoration outcomes. We collected seabed and water column observations across constructed reefs of three orientations representative of those found historically throughout the oyster’s range: parallel or perpendicular to tidal currents or circular. Areas adjacent to reefs were sites of fine sediment trapping, with lower flow velocities, evidence of particle settling, and more fine sediments on the seabed relative to off-reef reference sites. The water column above the reef crest exhibited higher acoustic backscatter, higher flow velocities, and larger particles in suspension, consistent with local erosion of flocculated fine sediment from the reef crest. Perpendicular reefs produced conditions that were more conducive to reef persistence and improved oyster performance, including high flow velocities and enhanced resuspension of sediments from the reef, compared to parallel or circular reefs. Particle trapping in areas between reefs has the potential to inhibit reef growth between existing reef structures, providing support for hypotheses of landscape-scale reef pattern formation. Oyster reef restoration efforts can benefit from this improved understanding of biophysical interactions arising from reef orientation that contribute to sediment dynamics on constructed oyster reefs.  相似文献   
45.
The paper investigates whether the methods chosen for representing uncertain geographic information aid or impair decision-making in the context of wildfire hazard. Through a series of three human subject experiments, utilizing 180 subjects and employing increasingly difficult tasks, this research evaluates the effect of five different visualizations and a text-based representation on decision-making under uncertainty. Our quantitative experiments focus specifically on the task of decision-making under uncertainty, rather than the task of reading levels of uncertainty from the map. To guard against the potential for generosity and risk seeking in decision-making under uncertainty, the experimental design uses performance-based incentives. The experiments showed that the choice of representation makes little difference to performance in cases where subjects are allowed the time and focus to consider their decisions. However, with the increasing difficulty of time pressure, subjects performed best using a spectral color hue-based representation, rather than more carefully designed cartographic representations. Text-based and simplified boundary encodings were among the worst performers. The results have implications for the performance of decision-making under uncertainty using static maps, especially in the stressful environments surrounding an emergency.  相似文献   
46.
47.
Brooke  Kaelan  Williams  Allison 《GeoJournal》2021,86(3):1275-1285

Therapeutic landscapes are reputed to have a lasting repute for realizing healing. Traditional therapeutic landscapes have recognized natural environments as often sought after places for well-being. Such places promote wellness via their close encounter with nature, facilitating relaxation and restoration, and enhancing a combination of physical, mental, and spiritual healing. The physical environment of Iceland is explored through a case study approach, primarily employing data from the field notebooks of post-secondary students travelling in Iceland, as well as the authors’ ethnographic field experience in Iceland. Iceland is examined using both a traditional understanding of therapeutic landscapes, as well as the contemporary understanding of the coloured landscape. In addition to the colour white, reflected in the glacial ice, moving water, and geo-thermal steams, black and various other colours in combination are discussed.

  相似文献   
48.
Moon snail predation on clams is a common model system of predator–prey interactions. In this system, the predator bores through the shell of its prey, leaving a distinct and identifiable hole. Some paleoecological and behavioral research on moon snails suggests a trend in predation preference directed toward clams with small shells. Rarely, however, have studies tested relative drilling frequencies across species and size ranges in natural assemblages of clam communities. We examined the clam community composition at two beaches in South Carolina, USA, and we then tested moon snail predator preferences for (a) clam prey species and (b) whether their selection is related to prey shell size. We collected a total of 1,879 clam shells, identified each shell to species and recorded their anteroposterior length. The species composition of clams differed significantly between the two beaches; Anadara ovalis was dominant at both sites, but three of ten total species were only collected at one beach. Folly Beach had nearly a 60% higher the overall drilling frequency (34.6%) versus Edisto Beach (21.8%), and this may be linked to the differences in clam community compositions at the sites. For A. ovalis and Mulinia lateralis, shells with larger lengths have lower probabilities of being bored by a moon snail. Anadara brasiliana, which generally is a thinner‐shelled clam species, had the highest total drilling frequency (77.2%), and Noetia ponderosa, a thicker‐shelled clam, had a considerably lower drilling frequency (12.0%). We conclude that both community level factors (species composition) and population characteristics (shell size distributions) may influence the local drilling frequency by moon snails.  相似文献   
49.
Lovina, classified as an ungrouped ataxite, is controversial and its identity as a meteorite has been questioned. In this work, we use Pb isotopes on targeted troilite nodules in Lovina as a test of its antiquity and provenance. Although precise ages cannot be obtained, LA‐ICP‐MS offers a rapid, straightforward procedure to establish the source of lead, whether ancient (meteoritic) or modern (terrestrial). For nine pristine, unweathered nodules in Lovina, we find a lead isotopic composition of: 206Pb/208Pb = 0.492 ± 0.003 (2σ, MSWD 0.79; 95%) and 207Pb/206Pb = 0.852 ± 0.003 (2σ, MSWD 1.09; 95%) with no detectable uranium. All lead compositions of the troilite fall in the range expected for modern environmental and mantle lead and are distinctly different from the primordial Canyon Diablo Troilite (CDT) composition of ancient meteoritic troilite. Although the origin of Lovina remains unknown, we conclude that lead in the Lovina troilite is unsupported by U decay and originated from a terrestrial source.  相似文献   
50.
NASA's Genesis mission revealed that the Sun is enriched in 16O compared to the Earth and Mars (the Sun's Δ17O, defined as δ17O–0.52×δ18O, is –28.4 ± 3.6‰; McKeegan et al. 2011). Materials as 16O‐rich as the Sun are extremely rare in the meteorite record. Here, we describe a Ca‐Al‐rich inclusion (CAI) from a CM chondrite that is as 16O‐enriched as the Sun (Δ17O = –29.1 ± 0.7‰). This CAI also has large nucleosynthetic anomalies in 48Ca and 50Ti (δ‐values are –8.1 ± 3.3 and –11.7 ± 2.4‰, respectively) and shows no clear evidence for incorporation of live 26Al; (26Al/27Al)0 = (0.03 ± 0.11) × 10–5. Due to their anomalous isotopic characteristics, the rare CAIs consistent with the Genesis value could be among the first materials that formed in the solar system. In contrast to the CAI studied here, the majority of CAIs formed in or interacted with a reservoir characterized by a Δ17O value near –23.5‰. Combined with 26Al‐26Mg systematics, the oxygen isotopic compositions of FUN (fractionation and unidentified nuclear effects), UN, and normal CAIs suggest that nebular conditions were favorable for solids to inherit this value for an extended period of time. Many later‐formed materials, such as chondrules, planetesimals, and terrestrial planets, formed in reservoirs with Δ17O near 0‰. The distribution could be easier to explain if the common CAI value of –23.5‰, which is consistent with the Genesis value within 3σ, represented the average composition of the protoplanetary disk.  相似文献   
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