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News Article | May 17, 2017
Site: www.eurekalert.org

Both natural and artificial beaver dams may alter stream temperatures which may benefit temperature-sensitive salmonid species, according to a study published May 10, 2017 in the open-access journal PLOS ONE by Nicholas Weber from Eco-Logical Research, Inc., USA, and colleagues. Beavers are ecosystem engineers, altering stream temperatures by building dams that increase surface water storage and connectivity with groundwater. Some studies suggest that the dams make water warmer and so are detrimental to salmonids, which are sensitive to temperature. Weber and colleagues tracked beaver dams and monitored water temperatures along 34 kilometers of the John Day River in Oregon over eight years. In addition, the team assessed the impact of artificial beaver dams on water temperature along four reaches of Bridge Creek. The researchers found that beaver dams may alter stream temperatures to the benefit of salmonids. Studies suggest that juvenile steelhead salmonids in Bridge Creek experience extreme stress at about 25°C, and the researchers found that maximum daily temperatures in much of the study stream exceed this temperature for much of the summer. However, temperatures rarely exceeded 25°C after the proliferation of beaver dams, likely because they help moderate temperatures both by increasing water storage and encouraging exchange between surface water and groundwater exchange. This fits with the fact that both beavers and salmonids were once more abundant and widely distributed in North America, and suggests that beaver dams could help mitigate the thermal degradation that can threaten sensitive species. Dr. Weber notes: "Beaver are often considered a keystone species, and their propensity to build dams plays an integral role in maintaining biodiversity and enhancing aquatic processes that benefit an array of aquatic and terrestrial organisms. Recognizing this, beaver relocation efforts and installation of structures designed to mimic the form and function of beaver dams are increasingly being used as effective and cost-efficient approaches for restoration of stream and riparian function. Despite this trend, the notion that beaver dams negatively impact stream habitat remains common, specifically the assumption that beaver dams increase summer stream temperatures to the detriment of cold-water species such as trout and salmon. However, by tracking beaver dam distributions and water temperatures throughout a high-desert, scientists have demonstrated that beaver dam can actually reduce high stream temperatures by increasing surface water storage and connectivity with cool groundwater. These results suggest that construction of artificial beaver dams and beaver relocation projects could be used to mitigate the impact of human induced thermal degradation that may threaten sensitive cold-water species." In your coverage please use this URL to provide access to the freely available article in PLOS ONE: http://journals. Citation: Weber N, Bouwes N, Pollock MM, Volk C, Wheaton JM, Wathen G, et al. (2017) Alteration of stream temperature by natural and artificial beaver dams. PLoS ONE 12(5): e0176313. https:/ Funding: Financial support for this project was provided by the Bonneville Power Administration (BPA Project Number: 2003-017) and the National Oceanic and Atmospheric Administration as part of the Integrated Status and Effectiveness Monitoring Program, and by the NOAA Western Regional Office. The funder provided support in the form of salaries for authors affiliated with Eco-Logical Research and South Fork Research but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the 'author contributions' section. Competing Interests: Nicholas Weber, Nicolaas Bouwes, Jacob Wirtz, and Gus Wathen are affiliated with Eco-Logical Research, and Carol Volk is affiliated with South Fork Research. There are no competing interests among Eco-Logical Research or South Fork Research that would alter the authors adherence to all the PLOS ONE policies on sharing data and materials.


Hall J.E.,National Oceanic and Atmospheric Administration | Pollock M.M.,National Oceanic and Atmospheric Administration | Hoh S.,John Day Fossil Beds National Monument | Volk C.,South Fork Research | And 2 more authors.
Ecosphere | Year: 2015

Degradation of dryland riparian ecosystems has been linked to the lowering of alluvial groundwater tables and reduced floodplain connectivity. Establishing riparian plants in dryland ecosystems with high water-stress and herbivore pressure presents major challenges for restoration practitioners. By planting at sufficient depths to reach lowered water tables, deep-planting provides direct access to water and encourages root development within hydrated soils. While deep-planting is a promising alternative to traditional supplemental irrigation in dryland areas affected by lowered water tables, few studies have evaluated deep-planting where planting depths must exceed one-meter to reach water tables and where herbivore protection is required. To evaluate deep-planting as an irrigation alternative where lowered water tables present a challenge to riparian restoration, we conducted experimental plantings along an incised stream within a semiarid watershed using deep-planting without supplemental irrigation in combination with several tree shelter designs. Our results indicate deep-planting cottonwood (Populus trichocarpa) and willow (Salix spp.) pole cuttings in augered holes that penetrated water tables up to 1.9 m below the surface significantly increased the probability of survival, with water table penetration significantly increasing the odds of survival by a factor of 7. Deep-planting with access to lowered water tables in combination with 0.9-m vented plastic tree shelters significantly increased the probability of survival, with over 50% higher survival after three years compared to unprotected and 1.-m circular fence caged plants that were also deepplanted with access to water. However, taller fence cages significantly reduced the probability of terminal bud loss from browsers with over 25% lower browse rates after three years. Therefore, we conducted additional experimental plantings to evaluate two taller plastic tree shelter designs to maximize survival while minimizing browsing. The results of our study indicate that deep-planting pole cuttings of cottonwood and willow with access to lowered water tables in combination with taller 1.8-m vented plastic tree shelters provided statistically similar survival as compared to the shorter 0.9-m vented plastic tree shelters after two years while significantly reducing browsing by approximately 75% two years after planting. © 2015 Hall et al.


Pollock M.M.,U.S. National Center for Atmospheric Research | Beechie T.J.,U.S. National Center for Atmospheric Research | Wheaton J.M.,Utah State University | Jordan C.E.,U.S. National Center for Atmospheric Research | And 3 more authors.
BioScience | Year: 2014

Biogenic features such as beaver dams, large wood, and live vegetation are essential to the maintenance of complex stream ecosystems, but these features are largely absent from models of how streams change over time. Many streams have incised because of changing climate or land-use practices. Because incised streams provide limited benefits to biota, they are a common focus of restoration efforts. Contemporary models of long-term change in streams are focused primarily on physical characteristics, and most restoration efforts are also focused on manipulating physical rather than ecological processes. We present an alternative view, that stream restoration is an ecosystem process, and suggest that the recovery of incised streams is largely dependent on the interaction of biogenic structures with physical fluvial processes. In particular, we propose that live vegetation and beaver dams or beaver dam analogues can substantially accelerate the recovery of incised streams and can help create and maintain complex fluvial ecosystems. © 2014 The Author(s).


Strand E.K.,University of Idaho | Bunting S.C.,University of Idaho | Starcevich L.A.,Western EcoSystems Technology Inc. | Nahorniak M.T.,South Fork Research | And 2 more authors.
Environmental Monitoring and Assessment | Year: 2015

Aspen woodland is an important ecosystem in the western United States. Aspen is currently declining in western mountains; stressors include conifer expansion due to fire suppression, drought, disease, heavy wildlife and livestock use, and human development. Forecasting of tree species distributions under future climate scenarios predicts severe losses of western aspen within the next 50 years. As a result, aspen has been selected as one of 14 vital signs for long-term monitoring by the National Park Service Upper Columbia Basin Network. This article describes the development of a monitoring protocol for aspen including inventory mapping, selection of sampling locations, statistical considerations, a method for accounting for spatial dependence, field sampling strategies, and data management. We emphasize the importance of collecting pilot data for use in statistical power analysis and semi-variogram analysis prior to protocol implementation. Given the spatial and temporal variability within aspen stem size classes, we recommend implementing permanent plots that are distributed spatially within and among stands. Because of our careful statistical design, we were able to detect change between sampling periods with desired confidence and power. Engaging a protocol development and implementation team with necessary and complementary knowledge and skills is critical for success. Besides the project leader, we engaged field sampling personnel, GIS specialists, statisticians, and a data management specialist. We underline the importance of frequent communication with park personnel and network coordinators. © 2015, Springer International Publishing Switzerland.

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