53 research outputs found

    The Relationship Between Measures of Annual Livestock Disturbance in Western Riparian Areas and Stream Conditions Important to Trout, Salmon, and Char

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    Managing livestock disturbance in riparian zones in a manner that provides economic returns to ranchers while protecting streams is an important aspect of rangeland management on public lands in the western United States. Attempts to balance economic and ecologic outcomes have been made more difficult due to the presence of several salmonid species that are protected under the Endangered Species Act. One approach to proper management of livestock use near streams has been to define the allowable limits of disturbance using 2 metrics, streambank alteration and stubble height. We evaluated 153 stream reaches within the Interior Columbia Basin to determine if these 2 surrogates of livestock disturbance measured after the vegetative growing season were associated with stream conditions important to salmonids evaluated the following summer. We found that each stream habitat attribute that was evaluated (width-to-depth ratio, streambank angle, percent undercut banks, streambank stability, residual pool depth, percent pools, percent pool-tail fine sediments \u3c2 mm, and wood frequency) trended toward lower-quality salmonid habitat as streambank alteration increased or as stubble height decreased. While the strength of these associations were variable, the slopes of the relationships suggest that managing the amount of streambank alteration or stubble height could influence stream conditions within the Interior Columbia Basin. Because improved stream conditions for salmonids corresponded to decreased livestock disturbance, the amount of disturbance allowed in a stream reach will need to reflect management expectations and the environmental setting within the allotment. As a starting point, we suggest the continued application of existing livestock disturbance standards in stream reaches with good habitat conditions, and the specification of more conservative disturbance standards in stream reaches that have degraded habitat conditions

    Beaver Dam Influences on Streamflow Hydraulic Properties and Thermal Regimes

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    Beaver dams alter channel hydraulics which in turn change the geomorphic templates of streams. Variability in geomorphic units, the building blocks of stream systems, and water temperature, critical to stream ecological function, define habitat heterogeneity and availability. While prior research has shown the impact of beaver dams on stream hydraulics, geomorphic template, or temperature, the connections or feedbacks between these habitat measures are not well understood. This has left questions regarding relationships between temperature variability at different spatial scales to hydraulic properties such as flow depth and velocity that are dependent on the geomorphology. We combine detailed predicted hydraulic properties, field-based maps with an additional classification scheme of geomorphic units, and detailed water temperature observations throughout a study reach to demonstrate the relationship between these factors at different spatial scales (reach, beaver dam complexes, and geomorphic units). Over a three-week, low flow period we found temperature to vary 2 °C between the upstream and downstream extents of the reach with a net warming of 1 °C during the day and a net cooling of 0.5 °C at night. At the beaver dam complex scale, net warming of 1.15 °C occurred during the day with variable cooling at night. Regardless of limited temperature changes at these larger scales, the temperature variability within a beaver dam complex reached up to 10.5 °C due to the diversity of geomorphic units. At the geomorphic unit scale, the highly altered flow velocity and depth distributions within primary geomorphic units provide an explanation of the temperature variability within the dam complex and insight regarding increases in habitat heterogeneity

    Evaluating Watershed Condition: Bottom Up Vs. Top Down Approaches?

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    Habitat degradation has been identified as one of the major factors affecting the declines of fishes in the Columbia River Basin. The condition of physical habitat and the biotic integrity of stream systems are often directly correlated with substantial alterations to key landscape attributes. As such, numerous approaches to measure watershed condition have been developed. Here, we compare two separate measures of watershed condition: 1) a GIS-based measure of condition, i.e., top down; and 2) a ground based assessment of condition, i.e., bottom up), using field data collected across 1200 sites in the Interior Columbia River Basin under the PIBO Effectiveness Monitoring Project. With our GIS approach, we integrate land management and natural disturbance from watershed upstream of sample reaches into an overall watershed condition score. With our bottom-up approach, we integrate stream temperature data, indices of macroinvertebrate health, and an index of physical habitat condition from reach-level field data into an overall condition score. Our results indicate significant differences in assessments of condition across the two methods, as the GIS approach ranked considerably more watersheds with management activities into a low condition category than found in the bottom-up approach. Conversely, the GIS approach also categorized most watersheds with no or minimal management activities, i.e., reference, as low risk, while the field-based, bottom up approach illustrated a wide range of condition of reference sites due to natural disturbances. Our results suggest GIS-based approaches tended to quantify the ‘risk’ rather than condition within watersheds. The bottom-up approach tended to quantify actual conditions within streams, without consideration of potential risks associated with land management activities. Here, we advocate the most beneficial approach that would be some combination of the two to help guide and prioritize restoration activities to enhance habitat conditions and minimize risk of catastrophic disturbances

    Quantifying Temporal Variability in Stream Habitat Data: Implications for Restoration and Monitoring

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    Quantifying natural and anthropogenic-induced levels of temporal variability is essential for robust trend analyses and for evaluating the effectiveness of restoration activities or changed management actions. Here, we used data collected as part of the Pacfish/Infish Biological Effectiveness Monitoring Project to evaluate the extent of temporal variability in instream habitat collected at the reach scale. We integrated habitat data collected yearly (2001-2009) at 50 sites experiencing a range of management activities into our analyses to better understand the consistency of temporal variability in watersheds with inherently different landscape characteristics and disturbance regimes. We initially decomposed variance estimates to remove site-to-site variability, sampling error, and year effects and use the remaining variance as a measure of site-specific temporal variability. We then relate this temporal variability to landscape, management, and climate attributes at multiple scales to better understand which characteristics result in more or less variability in habitat attributes at specific sites. Our results suggest temporal variability differs significantly across individual sites and attributes within sites, indicating our ability to detect significant changes as a result of management changes and/or restoration efforts are context dependent. The spatial scale of landscape attributes, e.g., stream buffer vs. catchment, related to temporal variability also varied across individual attributes. Our efforts highlight the importance of considering site specific measures of temporal variability as they relate to specific restoration and management goals

    Estimating Increased Transient Water Storage With Increases in Beaver Dam Activity

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    Dam building by beaver (Castor spp.) slows water movement through montane valleys, increasing transient water storage and the diversity of residence times. In some cases, water storage created by beaver dam construction is correlated to changes in streamflow magnitude and timing. However, the total amount of additional surface and groundwater storage that beaver dams may create (and, thus, their maximum potential impact on streamflow) has not been contextualized in the water balance of larger river basins. We estimate the potential transient water storage increases that could be created at 5, 25, 50, and 100% of maximum modeled beaver dam capacity in the Bear River basin, USA, by adapting the height above nearest drainage (HAND) algorithm to spatially estimate surface water storage. Surface water storage estimates were combined with the MODFLOW groundwater model to estimate potential increases in groundwater storage throughout the basin. We tested four scenarios to estimate potential transient water storage increases resulting from the construction of 1179 to 34,897 beaver dams, and estimated surface water storage to range from 57.5 to 72.8 m3 per dam and groundwater storage to range from 182.2 to 313.3 m3 per dam. Overall, we estimate that beaver dam construction could increase transient water storage by up to 10.38 million m3 in the Bear River basin. We further contextualize beaver dam-related water storage increases with streamflow, reservoir, and snowpack volumes

    Multi-scale environmental filters and niche partitioning govern the distributions of riparian vegetation guilds

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    Across landscapes, riparian plant communities assemble under varying levels of disturbance, environmental stress, and resource availability, leading to the development of distinct riparian life-history guilds over evolutionary timescales. Identifying the environmental filters that exert selective pressures on specific riparian vegetation guilds is a critical step in setting baseline expectations for how riparian vegetation may respond to environmental conditions anticipated under future global change scenarios. In this study, we ask: (1) What riparian plant guilds exist across the interior Columbia and upper Missouri River basins? (2) What environmental filters shape riparian guild distributions? (3) How does resource partitioning among guilds influence guild distributions and co-occurrence? Woody species composition was measured at 703 stream reaches and each species\u27 morphological and functional attributes were extracted from a database in four categories: (1) life form, (2) persistence and growth, (3) reproduction, and (4) resource use. We clustered species into guilds by morphological characteristics and attributes related to environmental tolerances, modeling these guilds\u27 distributions as a function of environmental filters-regional climate, watershed hydrogeomorphic characteristics, and stream channel form- and guild coexistence. We identified five guilds: (1) a tall, deeply rooted, long-lived, evergreen tree guild, (2) a xeric, disturbance tolerant shrub guild, (3) a hydrophytic, thicket-forming shrub guild, (4) a low-statured, shadetolerant, understory shrub guild, and (5) a flood tolerant, mesoriparian shrub guild. Guilds were most strongly discriminated by species\u27 rooting depth, canopy height and potential to resprout and grow following biomass-removing disturbance (e.g., flooding, fire). Hydro-climatic variables, including precipitation, watershed area, water table depth, and channel form attributes reflective of hydrologic regime, were predictors of guilds whose life history strategies had affinity or aversion to flooding, drought, and fluvial disturbance. Biotic interactions excluded guilds with divergent life history strategies and/or allowed for the co-occurrence of guilds that partition resources differently in the same environment. We conclude that the riparian guild framework provides insight into how disturbance and bioclimatic gradients shape riparian functional plant diversity across heterogeneous landscapes. Multiple environmental filters should be considered when the riparian response guild framework is to be used as a decisionsupport tool framework across large spatial extents. Copyright: © 2015 Hough-Snee et al

    Country Concepts and the Rational Actor Trap: Limitations to Strategic Management of International NGOs

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    Growing criticism of inefficient development aid demanded new planning instruments of donors, including international NGOs (INGOs). A reorientation from isolated project-planning towards holistic country concepts and the increasing rationality of a result-orientated planning process were seen as answer. However, whether these country concepts - newly introduced by major INGOs too - have increased the efficiency of development cooperation is open to question. Firstly, there have been counteracting external factors, like the globalization of the aid business, that demanded structural changes in the composition of INGO portfolios towards growing short-term humanitarian aid; this was hardly compatible with the requirements of medium-term country planning. Secondly, the underlying vision of rationality as a remedy for the major ills of development aid was in itself a fallacy. A major change in the methodology of planning, closely connected with a shift of emphasis in the approach to development cooperation, away from project planning and service delivery, towards supporting the socio-cultural and political environment of the recipient communities, demands a reorientation of aid management: The most urgent change needed is by donors, away from the blinkers of result-orientated planning towards participative organizational cultures of learning.Des critiques croissantes de l'aide au développement inefficace exigent de nouveaux instruments de planification des bailleurs de fonds, y compris les ONG internationales (ONGI). Une réorientation de la planification des projets isolés vers des concepts holistiques de la planification de l’aide par pays ainsi que la rationalité croissante d'un processus de planification orientée vers les résultats ont été considérés comme réponse. Toutefois, si ces concepts de pays - nouvellement introduites par les grandes OING eux aussi - ont augmenté l'efficacité de la coopération au développement est ouvert à la question. Tout d'abord, il y a eu l’impact des facteurs externes, comme la mondialisation de l'entreprise de l'aide, qui a exigé des changements structurels dans la composition des portefeuilles des OING vers la croissance de l'aide humanitaire à court terme. Cela était difficilement compatible avec les exigences de l'aménagement du territoire à moyen terme. Deuxièmement, la vision sous-jacente de la rationalité accrue de la planification, concentré sur les resultats, comme un remède pour les grands maux de l'aide au développement était en soi une erreur. Un changement majeur dans la méthodologie de la planification, étroitement liée à un changement d'orientation dans l'approche de la coopération au développement, qui n’est pas concentrer sur planification du projet et la prestation de services, mais qui soutienne l'environnement socio-culturel et politique des communautés bénéficiaires, exige une réorientation de la gestion de l’aide: Le changement le plus urgent est un changement par les donateurs eux-mêmes, qui devrait implanter des cultures de collaboration étroit avec les partenaires et la population locale

    Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

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    Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo
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