Article

Modeling the capacity of riverscapes to support beaver dams

December 2015
Geomorphology 277(1–3):-

DOI:10.1016/j.geomorph.2015.11.019

Authors:

William Wallace Macfarlane

Utah State University

Joseph M. Wheaton

Utah State University

Nick Bouwes

Anabranch Solutions

Martha Jensen

Utah State University

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Abstract The construction of beaver dams facilitates a suite of hydrologic, hydraulic, geomorphic, and ecological feedbacks that increase stream complexity and channel–floodplain connectivity that benefit aquatic and terrestrial biota. Depending on where beaver build dams within a drainage network, they impact lateral and longitudinal connectivity by introducing roughness elements that fundamentally change the timing, delivery, and storage of water, sediment, nutrients, and organic matter. While the local effects of beaver dams on streams are well understood, broader coverage network models that predict where beaver dams can be built and highlight their impacts on connectivity across diverse drainage networks are lacking. Here we present a capacity model to assess the limits of riverscapes to support dam-building activities by beaver across physiographically diverse landscapes. We estimated dam capacity with freely and nationally-available inputs to evaluate seven lines of evidence: (1) reliable water source, (2) riparian vegetation conducive to foraging and dam building, (3) vegetation within 100 m of edge of stream to support expansion of dam complexes and maintain large colonies, (4) likelihood that channel-spanning dams could be built during low flows, (5) the likelihood that a beaver dam is likely to withstand typical floods, (6) a suitable stream gradient that is neither too low to limit dam density nor too high to preclude the building or persistence of dams, and (7) a suitable river that is not too large to restrict dam building or persistence. Fuzzy inference systems were used to combine these controlling factors in a framework that explicitly also accounts for model uncertainty. The model was run for 40,561 km of streams in Utah, USA, and portions of surrounding states, predicting an overall network capacity of 356,294 dams at an average capacity of 8.8 dams/km. We validated model performance using 2852 observed dams across 1947 km of streams. The model showed excellent agreement with observed dam densities where beaver dams were present. Model performance was spatially coherent and logical, with electivity indices that effectively segregated capacity categories. That is, beaver dams were not found where the model predicted no dams could be supported, beaver avoided segments that were predicted to support rare or occasional densities, and beaver preferentially occupied and built dams in areas predicted to have pervasive dam densities. The resulting spatially explicit reach-scale (250 m long reaches) data identifies where dam-building activity is sustainable, and at what densities dams can occur across a landscape. As such, model outputs can be used to determine where channel–floodplain and wetland connectivity are likely to persist or expand by promoting increases in beaver dam densities.

The Beaver Restoration Assessment Tool Utah Wide

Data

December 2015

William Wallace Macfarlane · Joseph M. Wheaton · Nick Bouwes · Martha Jensen · John A Shivik

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The Use of Low-Tech Process-Based Stream Habitat Restoration

Technical Report

Full-text available

Dec 2024

Summary: This Fish Bulletin discusses low-tech process-based restoration of riverscapes and draws extensively from the work of Wheaton et al. (2019) to describe low-cost restoration techniques that can improve riparian, floodplain, and instream habitat in many California streams.

Analyse critique et réflexion quant à l'application et l'adaptation des modèles du Riverscapes Consortium sur le territoire et le contexte français : l'exemple du bassin versant de la Drôme

Thesis

Full-text available

Sep 2024

Clément George

Le Riverscapes Consortium est une collaboration internationale de chercheurs et de praticiens engagés dans la préservation du bon état de fonctionnement des corridors fluviaux. Pour ce faire, elle développe notamment, à l'Université d'Etat de l'Utah, des modèles dits de grade "production" à destination des gestionnaires. Ces modèles ont pour but de permettre la caractérisation des corridors fluviaux, ainsi que la priorisation des actions de restauration et de conservation. Ils utilisent pour ce faire des données géospatiales publiques, gratuites, et disponibles à l'échelle nationale. Cependant, ces modèles ne sont pour l'heure quasiment qu'exclusivement appliqués sur le territoire étasunien. Ils sont automatisés dans le cloud pour les bassins versants américains et leurs résultats sont disponibles sur une plateforme dédiée, le "Data exchange". La faisabilité de l'application de ces modèles sur un contexte radicalement différent du contexte étasunien, tel que le contexte français, n'était pas connue avant le début de ce stage. C'est dans ce contexte que s'inscrit le stage ayant donné naissance au présent document. L'objectif a donc été de tester la faisabilité d'une telle adaptation, via la création d'une base de données regroupant l'ensemble des couches de données géospatiales françaises utilisées et utilisables par les modèles, puis la modification de leurs scripts Python pour permettre leur fonctionnement avec les données françaises, la modification de certaines logiques des modèles, et la création de nouvelles symbologies et « Business Logics » (fichiers XML permettant l'affichage standardisé des résultats) françaises. Au total, quatre des huit modèles de grade "production" ont été appliqués et modifiés pour fonctionner avec les données françaises, à savoir un modèle de contextualisation des couches utilisées (Riverscapes Context), un modèle estimant la largeur à plein bord du réseau hydrographique (Channel Area Tool), un modèle d'analyses topographiques (TauDEM), et un modèle permettant la caractérisation des unités géomorphologiques des corridors fluviaux et notamment du fond de vallée (VBET). Ce projet appelle à être poursuivi. Des réflexions restent à mener sur la manière de adapter et d'appliquer les modèles suivants, et sur la pertinence même de l'application de certains d'entre eux (RCAT). A l'avenir, une calibration devra également être réalisée via télédétection et études de terrain, afin de permettre aux modèles de fournir des résultats exploitables sur le contexte français.

Critical analysis and reflection on the application and adaptation of the models of the Riverscapes Consortium to the French territory and context: the example of the Drôme watershed

Thesis

Full-text available

Sep 2024

Clément George

The Riverscapes Consortium is an international collaboration of researchers and practitioners dedicated to preserving the healthy functioning of riverscapes. To this end, it is developing "production" grade models for river managers, at Utah State University. The goal of these models is to characterize riverscapes and prioritize restoration and conservation efforts. To do this, they use free, public geospatial data available at a national scale. However, these models are currently applied almost exclusively in the USA. They are automated in the cloud for American watersheds, and their results are available on a dedicated platform, the " Data Exchange ". The feasibility of applying these models to a context radically different from that of the USA, such as France, was not known before the start of this internship. This was the context of the internship that produced the present document. The aim was, therefore, to test the feasibility of such an adaptation by creating a database containing all the French geodata layers used and usable by the models, then modifying their Python scripts to allow them to work with French data, modifying some of the models' logic, and creating new French symbologies and "business logics" (XML files allowing standardized presentation of results). A total of four of the eight "production" grade models were applied and modified to work with French data, namely a model for contextualizing the layers used (Riverscapes Context), a model for estimating the full bankfull width of the riverscape network (Channel Area Tool), a model for topographic analysis (TauDEM), and a model for characterizing the geomorphological units of riverscapes and particularly valley bottoms (VBET). This project needs to be continued. Further reflection is needed on how to adapt and apply the following models and on the relevance of applying some of them (RCAT). In the future, it will also be necessary to calibrate the models by means of remote sensing and field studies in order to obtain usable results in the French context.

Estimating Increased Transient Water Storage with Increases in Beaver Dam Activity

Article

Full-text available

May 2024

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.

Impacts of beaver dams on riverscape burn severity during megafires in the Rocky Mountain region, western United States

Chapter

Feb 2024

Megafires, defined as fires with burn areas greater than 100,000 acres (404.7 km 2), result partly from increasingly short wet seasons coupled with consistently hotter, drier summers, and partly from past forest management decisions. Historically rare, megafires have become increasingly common in recent years. In this study, we examined the impact of megafires on riverscapes with beaver dams to explore the resilience of these habitats. We investigated whether beaver-modified riverscapes are more resistant to the impacts of megafires than geomorphically similar riverscapes lacking beaver dams. Our analysis utilized remotely sensed and field-collected data from three Rocky Mountain region megafires that burned in 2020. Our results showed that riparian areas with beaver dams (1537 beaver dams, which occurred in 658 out of

Channel Gradient as a Factor in the Distribution of Beaver Dams and Ponds on Small Rivers: A Case Study in the Northern Extremity of the Volga Upland, the East European Plain

Article

Full-text available

Jul 2023

A very noticeable increase in the beaver population (mainly the Eurasian beaver (Castor fiber L.)) in the East European Plain since the end of the 20th century through reintroduction contributed to the emergence of a large number of beaver dams and ponds, which resulted in the transformation of the channels and the hydrological regime of small rivers. In this paper, for the first time in the Middle Volga region, regularities in the distribution of beaver dams and ponds on small rivers were revealed based on a topographic survey of the river channel, regulated by beaver activity in recent decades. The materials of the paper were obtained during field (geodetic) work in August and September of 2022 in the valleys of two small rivers typical for the north of the Volga Upland, Morkváshinka River (16.6 km) and Morkváshka River (7.8 km), with subsequent statistical processing. According to the results obtained, all the dams we encountered were located in the sections of their channels with relatively small (up to 1%) and medium (1–3%) average gradients. In the upper reaches of the rivers, the expansion of beaver activity is limited to the large gradients of their channels. Along the entire length, there is an alternation of sectors with a “natural” (not regulated by beavers) channel and a cascade of beaver ponds. Drained (at the time of the survey) sectors without dams, as well as those with preserved and destroyed dams, were also identified on the Morkváshinka River. On the whole, 26–48% of the length of the studied rivers has been transformed by beaver activity. The average number of dams per kilometer of the watercourse is 3.7–5.1. The most favorable channel gradients for beaver activity are 3.6–16.6 m/km, or 0.36–1.66%. The average gradient of the channel, above which no beaver dams and related ponds were found in these rivers, is 30 m/km, or 3%. An increase in the channel gradient upstream of the rivers is reflected in the size of beaver dams and ponds. The beaver dams and ponds are slightly larger in the sections of the rivers with a relatively small average gradient than in the sections with a medium average gradient of the channel.

EEAGER: A Neural Network Model for Finding Beaver Complexes in Satellite and Aerial Imagery

Article

Full-text available

May 2023

Beavers are ecosystem engineers that create and maintain riparian wetland ecosystems in a variety of ecologic, climatic, and physical settings. Despite the large‐scale implications of ongoing beaver conservation and range expansion, relatively few landscape‐scale studies have been conducted, due in part to the significant time required to manually locate beaver dams at scale. To address this need, we developed EEAGER—an image recognition machine learning model that detects beaver complexes in aerial and satellite imagery. We developed the model in the western United States using 13,344 known beaver dam locations and 56,728 nearby locations without beaver dams. Performance assessment was performed in twelve held out evaluation polygons of known beaver occupancy but previously unmapped dam locations. These polygons represented regions similar to the training data as well as more novel landscape settings. Our model performed well overall (accuracy = 98.5%, recall = 63.03%, precision = 25.83%) in these areas, with stronger performance in regions similar to where the model had been trained. We favored recall over precision, which results in a more complete catalog of beaver dams found but also a higher incidence of false positives to be manually removed during quality control. These results have far‐reaching implications for monitoring of beaver‐based river restoration, as well as potential applications detecting other complex landforms.

Effects of Beaver Dams on Stream and Riparian Conditions on Public Lands in the United States' Inland Northwest

Article

Full-text available

Dec 2022

Brett Roper

A before-after control-impact (BACI) design was used to simultaneously evaluate how stream habitat, macroinvertebrate communities, stream temperatures, and riparian conditions responded to beavers building damswithin a stream reach. Summarized conditions describing beaver-dammed and undammed stream reaches suggested that 13 of the 18 evaluated metrics differed. After accounting for beavers’ selection of lower-gradient stream reaches with less forested cover, the number of stream and riparian metrics that differed significantly dropped to 5. Beaver dams increased pool area and depth, despite failing to increase the frequency of wood >10 cm in diameter. This suggests that beavers build dams utilizing pieces of wood smaller than most monitoring programs count. Changes in stream and riparian conditions due to beavers were insufficient to alter macroinvertebrate metrics commonly used to assess water quality. The presence of beaver dams in a reach was associated with less vegetative and woody cover along the stream’s edge. The reduction of shrub cover and the presence of upstream beaver dams likely played a role in the small increases observed in water temperatures. The fact that beavers tended to build dams in reaches with elevated water tables may have minimized water temperature increases. Based on the beaver occupancy rate found in this study, changes in stream and riparian conditions due to new beaver dams should be expected in 5% to 15% of the stream reaches similar to those in this study over the next 2 decades. An increasing number of beavers occupying stream reaches represents animportant passive restoration approach that will improve the quality of aquatic systems on public lands.

Exploring the dynamics of flow attenuation at a beaver dam sequence

Article

Full-text available

Oct 2022

Beavers influence hydrology by constructing woody dams. Using a Before After Control Impact experimental design, we quantified the effects of a beaver dam sequence on the flow regime of a stream in SW England and consider the mechanisms that underpin flow attenuation in beaver wetlands. Rainfall‐driven hydrological events were extracted between 2009 and 2020, for the impacted (n=612) and control (n=634) catchments, capturing events seven years before and three years after beaver occupancy, at the impacted site. General additive models were used to describe average hydrograph geometry across all events. After beaver occupancy, Lag times increased by 55.9% in the impacted site and declined by 17.5% in the control catchment. Flow duration curve analysis showed a larger reduction in frequency of high flows, following beaver dam construction, with declines of Q5 exceedance levels of 33% for the impacted catchment and 15% for the control catchment. Using event total rainfall to predict peak flow, five generalised linear models were fitted to test the hypothesis that beaver dams attenuate flow, to a greater degree, with larger storm magnitude. The best performing model showed, with high confidence, that beaver dams attenuated peak flows, with increasing magnitude, up to between 0.5‐2.5 m3 s‐1 for the 94th percentile of event total rainfall; but attenuation beyond the 97th percentile cannot be confidently detected. Increasing flow attenuation, with event magnitude, is attributed to transient floodplain storage in low gradient/profile floodplain valleys that results from an increase in active area of the floodplain. These findings support the assertion that beaver dams attenuate flows. However, with long‐term datasets of extreme hydrological events lacking, it is challenging to predict the effect of beaver dams during extreme events with high precision. Beaver dams will have spatially variable impacts on hydrological processes, requiring further investigation to quantify responses to dams across differing landscapes and scales. This article is protected by copyright. All rights reserved.

Where the Wild Beavers Are: Climate and Landscape Controls on Beaver Pond Area in Snow‐Dominated Rangeland Headwaters

Article

Mar 2022

Beavers are of increasing interest as a mechanism for ecosystem restoration. However, the physical watershed characteristics that allow for successful beaver re‐establishment are not consistent across habitat suitability models. We delineated the extent of beaver impounded surface water in the Pole Mountain Area (PMA) of Southeastern Wyoming with six National Agricultural Imagery Program acquisitions over an 18‐year time period via a random forest classification algorithm. We computed beaver pond area for first and second‐order watersheds within the PMA and related the impounded pond area to climatic metrics such as maximum annual snow water equivalent and snow melt and rain input into the ground. There was no apparent relationship between annual climate metrics and beaver pond area. Further, we developed a random forest regression model to correlate beaver pond area with topographically derived watershed characteristics (e.g., hillslope size, riparian area size) to explore physical controls on impounded area at the watershed scale. Controls differed for first and second‐order watersheds, with pond area in smaller watersheds largely being controlled by lateral water contributions from the hillslopes, and in the larger watersheds by water from upstream and available space in the riparian areas. Interestingly, vegetation height did not emerge as an important predictor for pond area, likely because of generally good availability of forage material in all watersheds. This study improves our understanding of watershed characteristics that contribute to beaver habitat suitability and can be used to guide beaver re‐introduction efforts through analysis targeted at identifying watersheds most appropriate to beaver pond construction.

Estimating widespread beaver dam loss: Habitat decline and surface storage loss at a regional scale

Article

Full-text available

Mar 2022

The loss of beaver populations has commonly been accompanied by the failure of beaver dams, leading to stream incision, water table lowering, and the eventual transition from a beaver meadow to a drier riparian corridor. Widespread decline in North American beaver populations (Castor canadensis) has been documented from pre‐European settlement to the current day, representing an estimated 80% to 98% loss of historical populations. While individual case studies have investigated the ecosystem impacts of local beaver population loss, few studies have quantified large‐scale changes associated with widespread population decline. Here, we use the Beaver Restoration Assessment Tool to model landscape‐scale habitat suitability and beaver dam capacity in Colorado, USA, in order to determine whether a widespread loss in beaver population corresponds to a similar scale decline in the capacity to sustain beaver on the landscape and declines in physical benefits associated with beaver, such as surface water and sediment storage. Currently, the statewide stream network (298,119 stream kilometers) can support approximately 1.36 million beaver dams, compared with 2.39 million dams historically. All regions of Colorado have seen a decline in beaver dam capacity from historical conditions, likely due to agriculture, urbanization, and loss of vegetation necessary to beaver. Beaver dam capacity loss is accompanied by an approximate 40% decline in beaver‐mediated surface water and sediment storage potential across the state. Regions with high percent loss in storage potentials also had a high percentage of drainage network that had experienced beaver dam capacity losses of 15 or more dams per kilometer, which highlights the disproportionate impacts of losing high dam density reaches (i.e., beaver meadows). Extreme dam density declines were rare, and instead, most reaches have undergone a shift from high to moderate capacity. Statewide shifts in beaver dam capacity highlight the opportunity for using beaver‐related restoration in Colorado and across the American West.

When beavers get burned, do fish get fried? The role of beavers to mediate wildfire effects on Arctic Grayling in Boreal Alaska.

Thesis

Full-text available

Dec 2023

Will Samuel

Wildfire is a dominant natural disturbance process throughout boreal North America and fires are increasing in size, frequency, and severity. However, little is known about how wildfire affects boreal fish populations and aquatic habitat despite the substantial impacts of fire on ecosystem processes, and even less is known about how fire effects are mediated by species interactions. For example, North American Beavers (Castor canadensis) are affected by and can influence wildfire dynamics, and their engineering has complex effects on aquatic habitats. North American Beavers therefore have the potential to mediate wildfire effects on aquatic ecosystems and fish populations. Here I investigated relationships between wildfire and the distribution of beavers and a common fish species across a fire-dominated riverscape in Interior Alaska. First, I used satellite imagery to locate and enumerate beaver ponds throughout five large watersheds (total area: 20,711 km2) and modeled the relationship of beaver pond density (ponds per km2) as a function of wildfire history, stream geomorphology, hydrology, and vegetation composition. I then used a simulation to conceptualize the impacts of wildfire and beaver dams on Arctic Grayling (Thymallus arcticus) habitat availability under variable hydrologic conditions. Next, I sampled 62 streams for Arctic Grayling environmental DNA (eDNA) and sampled 10 of those streams for Arctic Grayling abundance. I used a generalized linear model (GLM) and N-mixture model to understand the relationship between eDNA concentration and Arctic Grayling abundance and distribution throughout the study area. I found that wildfire metrics explained most variation in beaver pond density (pseudo R2 = 0.75) across the landscape and were positively associated with beaver pond density, although geomorphological and hydrological parameters were also important. My simulations indicated that beaver dams can create substantial barriers to fish dispersal during low water conditions (up to 20% reduced habitat availability in some river basins) and can severely reduce (up to 65%) habitat availability in some tributary streams. I found that eDNA concentration was moderately correlated with Arctic Grayling abundance (GLM: pseudo R2 = 0.45) and unexplained variation was likely due to the spatial mismatch between fish sampling and scale of eDNA representation. However, I estimated eDNA residence time of about 6.7 hours in one stream, and eDNA appeared to accumulate longitudinally throughout the tributary, indicating that an eDNA sample near the downstream end was likely a good relative representation of Arctic Grayling abundance in a tributary. Results from the N-mixture model indicated that stream geomorphology and hydrology were the most important predictors for Arctic Grayling abundance (eDNA concentration), wildfires had a negative effect, and beaver dam density had a mixed effect on Arctic Grayling abundance. Overall, this study illustrated that beaver densities can increase after wildfires in Interior Alaska stream networks, which could result in negative impacts on Arctic Grayling habitat availability if beavers impair fish passage; however, these effects are dependent on the environmental context and suggest beaver-fish interactions may be best managed on a case-by-case basis.

Beaver dam analogs did not improve beaver translocation outcomes in a desert river

Article

Feb 2024

Stream restoration programs employ beaver‐related restoration techniques, including beaver translocations and installation of beaver dam analogs (BDA), to create complex in‐stream habitat. We investigated whether BDA installations improved the probability of translocated beavers surviving and colonizing a section of a degraded desert river. We translocated beavers fitted with tracking devices to the Price River, Utah, United States, for 2 years before and after BDAs were installed. We monitored survival and site fidelity of beavers to estimate apparent survival ( φ ), using model selection to evaluate models with BDA, flow, and other factors hypothesized to relate to apparent survival. We found similar apparent survival 8 weeks post‐release of pre‐BDA ( φ = 0.50 ± 0.08 SE) and post‐BDA beavers ( φ = 0.41 ± 0.06 SE). There were 15 predator‐caused mortalities and 39 beavers emigrated out of the study site. Top models indicated apparent survival was negatively related to mean flow. Of the 70 BDAs constructed, beaver activity was detected on only two structures and the number of intact natural dams decreased due to monsoon floods. Our results suggest BDAs may not improve survival and site fidelity of translocated beavers in desert river systems. Instead, the dynamic flow of desert rivers and negative relationship between flow and apparent survival suggest the timing of release may be an important consideration for successful beaver translocation. Additional research is needed to understand how habitat, food availability, individual behavior, and resident conspecifics influence beaver translocation success.

When beavers get burned, do fish get fried? The role of beavers in mediating wildfire effects on freshwater fish habitat in boreal Alaska

Presentation

Aug 2023

Youtube Link: https://youtu.be/-xJtwNYtgpk Wildfire is a dominant natural disturbance process throughout boreal North America and fires are increasing in size, frequency, and severity. However, little is known about how wildfire affects boreal fish habitat and populations despite the substantial impacts of fire on ecosystem processes, and even less is known about how fire effects may be mediated by species interactions. For example, North American beavers (Castor canadensis) are affected by and can influence wildfire dynamics, and they have complex effects on aquatic habitats. Therefore, beavers have the potential to mediate wildfire effects on aquatic systems and subsequently, fish populations. We used satellite imagery to locate and enumerate beaver ponds in five large watersheds (20,711 km2) in Interior Alaska, and modeled relationships among beaver pond density, wildfire history, and other relevant landscape-level characteristics including stream geomorphology, watershed topology, hydrology, and vegetation. We found on average 6.4 ponds per 100 km2 and a mean pond area of 2,312 m2 per 100 km2; ponds were patchily distributed throughout the study area and highly variable in size. A variety of predictors influenced beaver pond density, and wildfire parameters were important in multiple models. Our next steps are to use a theoretical approach to estimate the potential distribution of Arctic Grayling (Thymallus arcticus) with respect to beaver dams under high and low stream flows in contrast to fish distribution in streams without beavers. Overall, our work highlights the significant effects of wildfire on fish and wildlife distributions in the boreal biome and begins to disentangle the complex and interactive effects of wildfire and beavers on fish.

Avian Monitoring at Daly Creek, Eagle Creek, and Sturgill Creek HMAs, 2012- 2018

Technical Report

Aug 2018

Anthonie M. A. Holthuijzen

Starting in 2007, riparian woody vegetation along the main Daly Creek drainage continues to recover after restriction of livestock grazing and aided by rapidly expanding beaver activity. At the Eagle Creek MU, an improved and upgraded irrigation water distribution system has resulted in wet meadow complexes and expanding native herbaceous plant populations. Increasing complexity in the vertical structure of vegetation along the Daly Creek drainage and an expanding, connected riparian corridor is expected to positively influence the abundance and diversity of avian communities. Improved wetland conditions at the Eagle Creek MU are hypothesized to lead to more diverse plant communities and associated avian community. The general objective of this study is to document changes in avian abundance and composition at the Daly Creek drainage and Eagle Creek MU during 2012-2018. Specific objectives are to determine: 1) the abundance, diversity and composition of avian communities during the nesting season (middle of June through the middle of July) and 2) changes in avian community composition and abundance in relation to shifting riparian habitat conditions. Daly Creek drainage are referred to as “Daly Creek” and the Eagle Creek MU as “Eagle Creek”. Annually, up to 20 sites were surveyed at Daly Creek and 11 sites at Eagle Creek. Fixed, permanent circular point counts were used that were monitored for 8-min each during each survey. Monitoring started in spring 2012 and 2013 at Daly- and Eagle Creek, respectively and continued annually through 2017. Surveys were conducted in spring and summer, except in 2015 when sites were only monitored in summer. I monitored Forested Wetland, Scrub-Shrub Wetland cover types at Daly Creek and Grassland (wet meadows) and Scrub-Shrub Wetland and Forested Wetland at Eagle Creek. Bird abundances and composition along Daly Creek showed limited change over time. No differences were found between summer and spring bird abundances for Forested Wetland and Scrub-Shrub Wetland vegetation cover types. At Eagle Creek, Scrub-Shrub Wetland and Forested Wetland showed the highest bird densities compared to Grassland. Summer bird densities in Forested Wetland were significantly higher in 2015 than in other years, but not for spring surveys. Species diversity was higher for Scrub-Shrub Wetland compared to Forested Wetland at Daly Creek, but no differences were found between summer and spring for each of the vegetation cover types over the monitoring period. At Eagle Creek, summer bird diversity was highest in 2015 compared to other years. No other differences were found among cover types, among years for each cover type, or seasons. Shannon diversity indices were remarkably similar between the 2 vegetation cover types for each of the areas monitored, paralleled by evenness, without a clear temporal trend. Generally, community analyses did not show strong unidirectional trends of avian communities for the vegetation cover types monitored. Avian communities for vegetation cover types at both Daly Creek and Eagle Creek became more similar during 2012 through 2018, but showed a modest difference between monitoring sites at Daly Creek and Eagle Creek. In conclusion, changes to the avian abundance and diversity at Daly Creek and Eagle Creek were at most weak and changes in avian community composition modest. At Daly Creek the riparian (woody) vegetation is narrow, fragmented, and lacks large, mature trees that provide spatial and structural habitat diversity to multiple avian guilds. This may provide an explanation for similar avian abundances and diversity over the monitoring period. Changes in management at Eagle Creek have been recent (2014 and 2015) and have only modestly influenced avian abundance and diversity

A comparison of methods for estimating juvenile salmon habitat capacity to assist with restoration planning and evaluation

Article

Full-text available

Jan 2023

Objective A variety of analytical approaches have been developed in recent years to estimate salmon Oncorhynchus spp. freshwater habitat capacity to assist with planning and evaluating habitat restoration. We compared and contrasted seven different methods for estimating juvenile Chinook Salmon O. tshawytscha habitat rearing capacity (total number of fish that a given area of habitat can support), abundance, and habitat suitability in a 3.2‐km reach of the Grande Ronde River, Oregon. Methods This included approaches that used statistical methodologies applied to existing empirical data sets, including quantile random forests (QRFs) and spatial stream networks (i.e., Fish Data Analysis Tool [FDAT]), and deterministic models that included the habitat suitability index, the unit characteristic method (UCM), and three habitat expansion methods. Result We hypothesized that the methods would provide comparable estimates. However, the approaches provided very divergent estimates for the same stream reach, ranging from 1048 to 24,530 juvenile Chinook Salmon. The simple habitat expansion methods appeared to be the most similar to the actual parr (juvenile) abundance obtained from recent snorkel surveys (4179 juveniles). The fish density data (fish/m ² ) and habitat data used in the models were likely the main drivers of the differences between the UCM and habitat expansion methods. Conclusion The habitat expansion approaches, which are based on detailed habitat surveys, appear to be particularly suitable for estimating capacity within a reach; thus, they may be suitable for evaluating changes due to habitat restoration. The model‐based approaches (QRF and FDAT) appear to yield coarser estimates, in part because they use various inputs at the reach and landscape scales. As such, they are more useful for relative comparisons among reaches in watersheds to assist with watershed‐scale restoration planning and prioritization. Because all of the methods rely on fish density in different types of habitats, regional or local data on fish densities would improve their accuracy.

Monitoring, modelling and managing beaver ( Castor fiber ) populations in the River Otter catchment, Great Britain

Article

Full-text available

Aug 2022

Eurasian beaver (Castor fiber) were nearly hunted to extinction but have recovered to occupy much of their former range. Beaver were extirpated from Great Britain c. 400 years ago but have recently been reintroduced. The River Otter catchment, Devon was the site of the first licensed wild release of beavers in England. With further releases being considered, there is a need to better understand population dynamics of this native, keystone species to inform conservation and management. Field signs were surveyed from 2015 to 2021. A semi‐automated territory detection method was adopted to estimate territory counts. A spatially explicit model was developed to estimate the ecological territory capacity of the catchment. Future territory expansion was modelled using logistic growth curves; initial growth rate was estimated from observed territory counts and the estimated territory capacity range was used to define the limiting value of the growth curve. Beaver territory removal was simulated, across a range of management intensities and start times, to determine potential impacts of translocation or lethal control upon population dynamics. Territory numbers increased from four to 18, inclusive of four additionally released individuals, during study period. In the absence of population management, the territory capacity of the catchment was estimated to range between 120 and 183; this may be reached between 2028 and 2057. Simulated territory removal, where territories were removed at a fixed rate from the sum of the estimated total population and the population increase for that year, demonstrated large uncertainties in predicted population responses. Simulations with territory removals >3/year all predicted potential population collapse. This finding emphasizes the need for caution when considering population management strategies; translocation of animals out of the catchment or culling should be considered only when populations are established and all alternatives have been considered. These results provide critical information for the expected rate and magnitude of beaver population change in the River Otter catchment. The methods provide a reproducible and generalizable approach for understanding beaver population change, which can inform policy on the reintroduction of beavers and the potential timing and intensity of future beaver population management.

Natural infrastructure in dryland streams (NIDS) can establish regenerative wetland sinks that reverse desertification and strengthen climate resilience

Article

Full-text available

Aug 2022
SCI TOTAL ENVIRON

In this article we describe the natural hydrogeomorphological and biogeochemical cycles of dryland fluvial ecosystems that make them unique, yet vulnerable to land use activities and climate change. We introduce Natural Infrastructure in Dryland Streams (NIDS), which are structures naturally or anthropogenically created from earth, wood, debris, or rock that can restore implicit function of these systems. This manuscript further discusses the capability of and functional similarities between beaver dams and anthropogenic NIDS, documented by decades of scientific study. In addition, we present the novel, evidence-based finding that NIDS can create wetlands in water-scarce riparian zones, with soil organic carbon stock as much as 200 to 1400 Mg C/ha in the top meter of soil. We identify the key restorative action of NIDS, which is to slow the drainage of water from the landscape such that more of it can infiltrate and be used to facilitate natural physical, chemical, and biological processes in fluvial environments. Specifically, we assert that the rapid drainage of water from such environments can be reversed through the restoration of natural infrastructure that once existed. We then explore how NIDS can be used to restore the natural biogeochemical feedback loops in these systems. We provide examples of how NIDS have been used to restore such feedback loops, the lessons learned from installation of NIDS in the dryland streams of the southwestern United States, how such efforts might be scaled up, and what the implications are for mitigating climate change effects. Our synthesis portrays how restoration using NIDS can support adaptation to and protection from climate-related disturbances and stressors such as drought, water shortages, flooding, heatwaves, dust storms, wildfire, biodiversity losses, and food insecurity.

Park County Beaver Restoration Assessment

Technical Report

Full-text available

Feb 2022

This study outlines a pragmatic professional-judgment assessment of the potential for using low-tech process-based restoration (LTPBR) approaches for restoring riverscapes with beavers in Park County, Colorado. The method allows professionals to apply knowledge and data from many sources in the evaluation of current beaver activity, capacity, limiting factors, and restoration potential to prioritize opportunities.

MONTANA BEAVER DAM CENSUS & BEAVER RESTORATION ASSESSMENT TOOL (BRAT) VERIFICATION

Technical Report

Full-text available

Sep 2024

The Ecology and Evolution of Beavers: Ecosystem Engineers That Ameliorate Climate Change

Article

Aug 2024

Beavers, Castor canadensis in North America and Castor fiber in Eurasia, are widely referred to as nature's engineers due to their ability to rapidly transform diverse landscapes into dynamic wetland ecosystems. Few other organisms exhibit the same level of control over local geomorphic, hydrologic, and ecological conditions. Though freshwater ecosystems are particularly vulnerable to changing climate, beavers and their wetland homes have persisted throughout the Northern Hemisphere during numerous prior periods of climatic change. Some research suggests that the need to create stable, climate-buffered habitats at high latitudes during the Miocene directly led to the evolution of dam construction. As we follow an unprecedented trajectory of anthropogenic warming, we have the unique opportunity to describe how beaver ecosystem engineering ameliorates climate change today. Here, we review how beavers create and maintain local hydroclimatic stability and influence larger-scale biophysical ecosystem processes in the context of past, present, and future climate change.

Features of the Distribution of Beaver Dams and Ponds along Small Rivers: The Volga-Kama Region, European Russia

Article

Full-text available

Apr 2024

In this paper, by using GNSS technologies, some features of the distribution and some morphometric parameters of dams and ponds created by the Eurasian beaver (Castor fiber L.) along ten rivers of the Volga-Kama region of European Russia were identified. Detected features depend on the geomorphological, lithological, and landscape features of these rivers and their basins. The significant role of river slopes, as well as landscape zoning, in the distribution of beaver dams and ponds along small rivers in the study region is shown. In the rivers under study, almost all beaver constructions are located on riverbed slopes of less than 3% (most often, less than 2%). In the south of the forest zone (the southern taiga of the Vyatka River basin), the majority of dams and ponds (about 90%) are located on slopes of less than 1%, while, within the uplands of the forest-steppe zone, this location varies depending on the length of the rivers. In general, the greater the average slope of the river (the greater the average elevation of the river basin), the lower, other things being equal, the degree of beaver transformation of such rivers. This feature is better expressed in the rivers of the forest landscape zone and less expressed in the rivers flowing in the forest-steppe zone. Analysis of the morphometric parameters of beaver dams shows statistically significant trends towards an increase in their average height, as the channel slopes increase. Statistically significant trends were also identified towards a decrease in the length of dams and the length of associated ponds, with an increase in channel slopes. It is noteworthy that the critical values of the slope for a statistically significant and relatively sharp change in these parameters are 1.45%, 1.07 (or 0.54)%, and 0.65 (or 0.47)%, respectively. The greatest average heights of beaver dams are confined to those rivers where their basins are composed of loamy rocks/soils (especially those that are poorly plowed), compared with "sandy" river basins. This may be due to the peculiarities of the ratio of surface and underground water runoff in these basins and, as a consequence, different intensities of snowmelt-and rainfall-induced flood flow. We assume that the above-mentioned features reflect the early stages of beaver expansion (population growth) in the studied rivers.

Biogeomorphic processes, spatial heterogeneity, and river corridor resilience to stand-killing wildfire

Chapter

Full-text available

Feb 2024

Wildfire biogeomorphology is an integrative science fundamental in understanding the dynamic processes of adjustment that occur after wildfires. This volume draws together interdisciplinary studies that highlight key insights important to support heterogeneity, biodiversity, and resilience in fluvial ecosystems. Post-wildfire sediment pulses that change the physical elements of fluvial habitat may be transitory or long-lasting, for example, depending on variations in post-wildfire climate conditions. How biological processes and feedback alter post-wildfire geomorphic responses is also important to enhance ecosystem resilience. The syntheses point to greater emphasis on integrated approaches to advance strategies for ecosystem management toward conservation, restoration, and sustainable practices, in particular, to accommodate multiple possible postfire disturbance and recovery trajectories.

Geomorphic context in process‐based river restoration

Article

Full-text available

Jan 2024

Process‐based river restoration seeks to restore processes such as channel‐floodplain connectivity that create and maintain river corridor functions. Process‐based restoration can fail to produce the desired results if geomorphic context is not effectively incorporated into restoration design. Geomorphic context of a river reach refers to the controls on contemporary river form and process. Controls at the catchment‐ to reach‐scale include geologic history, biophysical characteristics, legacies of past human alterations, position within the river network, river corridor geometry, base level stability, disturbance regime, and contemporary human alterations of the river corridor. We conceptualize a river corridor as reflecting the interactions among fluxes of material and the geomorphic context. We discuss how an understanding of geomorphic context can be used to select a restoration approach and provide examples of how restoration can fail to achieve desired outcomes when geomorphic context is not considered. Within the toolbox of methods used to implement process‐based restoration, we differentiate the alteration of inputs to the river corridor and fluxes of material through the corridor from alteration of form and/or connectivity within the river corridor. Historical, biotic, geologic/geomorphic, and reference sites can be used to inform process‐based restoration targets. Restoration is strongly influenced by human perceptions of what is appropriate and achievable at a site and diverse communities influencing restoration at a site may differ in their perceptions. Geomorphically based conceptual guidelines, such as the River Styles Framework, provide an effective platform for incorporating an understanding of geomorphic context into process‐based river restoration.

Climate Change-Driven Cumulative Mountain Pine Beetle-Caused Whitebark Pine Mortality in the Greater Yellowstone Ecosystem

Article

Full-text available

Nov 2023

An aerial survey method called the Landscape Assessment System (LAS) was used to assess mountain pine beetle (Dendroctonus ponderosae)-caused mortality of whitebark pine (Pinus albicaulis) across the Greater Yellowstone Ecosystem (59,000 km2; GYE). This consisted of 11,942 km of flightlines, along which 4434 geo-tagged, oblique aerial photos were captured and processed. A mortality rating of none to severe (0–4.0 recent attack or 5.0–5.4 old attack) was assigned to each photo based on the amount of red (recent attack) and gray (old attack) trees visible. The method produced a photo inventory of 74 percent of the GYE whitebark pine distribution. For the remaining 26 percent of the distribution, mortality levels were estimated based on an interpolated mortality surface. Catchment-level results combining the photo-inventoried and interpolated mortality indicated that 44 percent of the GYE whitebark pine distribution showed severe old attack mortality (5.3–5.4 rating), 37 percent showed moderate old attack mortality (5.2–5.29 rating), 19 percent showed low old attack mortality (5.1–5.19 rating) and less than 1 percent showed trace levels of old attack mortality (5.0–5.09). No catchments were classified as recent attacks indicating that the outbreak of the early 2000’s has ended. However, mortality continues to occur as chronic sub-outbreak-level mortality. Ground verification using field plots indicates that higher LAS mortality values are moderately correlated with a higher percentage of mortality on the ground.

Using a digital elevation model to place overland flow fields and uncleaned ditch sections for water protection in peatland forest management

Article

Full-text available

Mar 2023
ECOL ENG

Peatland forest management is an important source of human-induced additional nitrogen, phosphorus, and organic carbon loads to surface waters in Finland. Ditch network maintenance (DNM) is typically used to ensure sufficient soil drainage for profitable timber production on peatland sites, but nutrient mobilization, particularly of phosphorus, and suspended sediment loads from ditches can cause harmful ecological effects on the quality of water courses. Various water protection structures have been developed to capture the loads released after treatments and to decrease the management impacts in forestry. Overland flow fields are efficient mechanisms for water purification, but they are rarely used in practice due to difficulties in finding suitable locations. In addition, leaving breaks between cleaned ditch sections is recommended wherever possible, as uncleaned sections decrease flow velocity and enhance sediment deposition from runoff water. To plan the most adequate protection methods in DNM, new GIS-based tools are needed to propose e.g. appropriate locations for water protection structures. We developed a spatial analysis to suggest locations for overland flow fields and uncleaned ditch sections within the catchment of lake Kovesjärvi (Parkano, Western Finland). Airborne lidar data consisting of 5 pulses m−2 enabled detailed terrain analysis and finding strictly specified terrain properties that satisfied the conditions of the water protection structures. Half of the field-reviewed overland flow fields were evaluated as good suggestions by forest management professionals and researchers. The model for uncleaned ditch sections worked well on the relatively flat study area, as 77% of the field-reviewed suggestions were rated good by expert opinions. Overall, the approach was evaluated to be useful in peatland forest management. Model parameters can be modified for various topographies, but more studies are needed prior to wider use of the model.

Technical Status Evaluation of River Training Works Based on the Improved DS Evidence Theory

Chapter

Full-text available

Feb 2023

A large number of river training works have been built in the inland waterway regulation projects to improve ship navigation conditions. However, water damages to river training works happen frequently in practice. Technical status evaluation of river training works is regarded as a fundamental content of inland waterway maintenance. Due to the various influencing factors and complex mechanisms, the content involved in the standard files is recognized as qualitative and no quantitative evaluation method is recommended so far. The technical status of river training works is currently evaluated through on-site investigation which is time-consuming and individual-dependent. By means of multi-source sensors, massive status data of river training works could be obtained instantaneously. Study on the technical evaluation model based on the multi-source information fusion theory attracts more attention in recent years. The classical DS evidence theory could fail as evidence conflict occurs. Thus, the Pearson’s correlation coefficient is calculated and utilized to update the probability distribution in the present study. A novel technical status evaluation model based on the improved DS evidence theory is established. The model is further verified through three case studies of traditional river training works (spur dike and flexible mattress belt) in the Yangtze River, China. The model outputs are consistent with the technical survey reports as well as the published research article. Quantitative and accurate evaluation of river training works could be accomplished by applying the proposed evaluation model. Moreover, the model could be embedded in the Inland Electronic Chart Display and Information System. The present study would provide theoretical basis for inland waterway maintenance and infrastructure monitoring in the future.

The Relationship between Disturbance Events and Substantial Changes in Stream Conditions on Public Lands in the Inland Pacific Northwest

Article

Full-text available

Nov 2022

Hydrologic, terrestrial and biologic disturbances are factors influencing stream channel conditions important to the persistence of aquatic biota. Past studies of how disturbance events alter streams have focused on fires, floods, and debris torrents as the magnitude of these events make them easy to detect. This approach has led to a bias in understanding which disturbances are likely to affect stream conditions. To address this concern, we used stream habitat data to identify where a substantial change in stream conditions had occurred and then used photographs of the evaluated reach to determine the disturbance that potentially caused those changes. We evaluated conditions in over 2000 stream reaches and found nearly a quarter of them had seen a substantial change in at least one of the five stream channel characteristics ‐ bankfull width, wood frequency, median particle size, pool depth, and bank stability – in the two decades these streams were monitored. Although many stream reaches were affected by charismatic disturbance events such as fires, floods, and mass wasting, the majority of the substantial changes we observed in channel conditions were related to small scale disturbances. Mechanisms such as beavers, tree fall, vegetative growth, grazing, and active restoration all played an important role in bringing about large changes in stream channel conditions. While the majority of the disturbances were natural, some channel changes remain tied to anthropogenic activities. Our results suggest no single sampling approach can be used to evaluate how stream conditions respond to all disturbances as they vary in intensity, over space and time, and which stream attribute is measured. By better understanding the full range of possible disturbances, managers should be better able to use such events to improve outcomes for streams and aquatic biota.

Groundwater‐Mediated Influences of Beaver‐Mimicry Stream Restoration: A Modeling Analysis

Article

Full-text available

Jul 2022

Beaver‐mimicry stream restoration (BMR) involves the alteration of a stream channel to approximate the effects of beaver activity. Project objectives often include increasing groundwater storage and dry‐season streamflow, but limited data are available to understand the nature of its effects on groundwater dynamics. We developed generic groundwater models of mountain headwater streams to investigate the effects of installing a single beaver‐mimicry structure (BMS) using different restoration designs in varied hydrogeologic settings. The magnitude of changes in dry‐season net stream gains from a single BMS was always a minor component of the channel water balance, and would be too small to measure in the field; however, the modeled patterns of change caused by a single BMS help to understand the underlying mechanisms. All tested scenarios caused increases in groundwater recharge from the stream, which resulted in increased groundwater levels, and groundwater outflow from the model domain. For scenarios that did not include evapotranspiration, most treatments in gaining and losing settings caused slight increases in dry‐season net stream gains, but in strongly losing settings net stream gains were reduced. The addition of simulated evapotranspiration often resulted in decreased dry‐season net stream gains, since evapotranspiration increased with groundwater elevations. BMR design and siting influence the types of hydrologic effects that should be anticipated.

Physical and Biological Characterization of the Yampa River Basin Via Remote Assessment Data Synthesis Report

Technical Report

Full-text available

Jul 2021

In order to characterize physical and biological conditions across the four planning segments of the Yampa Basin that comprise the geographical extent of the Yampa IWMP, a set of hydrogeomorphic and ecological indicators and associated metrics was developed. Each indicator described in this report was assessed based on remotely measurable metrics that together provide a holistic understanding of river health and its degree of functionality. To the extent supported by available data, we have assessed indicators that are either currently used in the Yampa Basin or are otherwise relevant to assessing the hydrogeomorphic and ecological conditions within the basin. The selected indicators account for TSC priorities, project objectives, data availability, riverscape principles, and ability of remote sensing methods to accurately characterizing trends in river health. For each indicator, we include the metrics that support examination of that indicator and assess the quantity and quality of available data to evaluate those variables.

Beaver: The North American freshwater climate action plan

Article

Full-text available

Apr 2022

Rivers and streams, when fully connected to their floodplains, are naturally resilient systems that are increasingly part of the conversation on nature‐based climate solutions. Reconnecting waterways to their floodplains improves water quality and quantity, supports biodiversity and sensitive species conservation, increases flood, drought and fire resiliency, and bolsters carbon sequestration. But, while the importance of river restoration is clear, beaver‐based restoration—for example, strategic coexistence, relocation, and mimicry—remains an underutilized strategy despite ample data demonstrating its efficacy. Climate‐driven disturbances are actively pushing streams into increasingly degraded states, and the window of opportunity for restoration will not stay open forever. Therefore, now is the perfect time to apply the science of beaver‐based low‐tech process‐based stream restoration to support building climate resilience across the landscape. Not every stream will be a good candidate for beaver‐based restoration, but we have the tools to know which ones are. Let us use them. This article is categorized under: Science of Water > Hydrological Processes Water and Life > Nature of Freshwater Ecosystems Water and Life > Conservation, Management, and Awareness

Riverscape Conservation, Restoration and Monitoring Plan: Dugout Ranch, Utah

Technical Report

Full-text available

Dec 2021

In this report we present a conservation, restoration and monitoring plan for the streams and riparian areas of Dugout Ranch, Utah, owned and operated by The Nature Conservancy (TNC). The plan is intended to help guide conservation, restoration and management of the Dugout Ranch’s riverscapes (streams and riparian areas) over the next several decades and is also developed as an adaptive management plan to facilitate learning. The recommended conservation and restoration actions are intended to maintain and enhance native riparian vegetation and instream biota. Many terrestrial animals that use the riparian zone or migrate through the riverscape are also anticipated to benefit from the plan. The recommended conservation and restoration actions are based on the best available information regarding the current ecological and geomorphic conditions and restoration recovery potential as well as ranch management objectives. We prioritized reaches for conservation and restoration actions using condition assessment models, expert opinion and field observations. We recommend an experimental design for implementation of conservation and restoration actions. Combined with monitoring, the experimental design is aimed at identifying the most successful conservation and restoration actions for maintaining complex instream habitat and a healthy native riparian community.

Do metapopulations and management matter for relict headwater bull trout populations in a warming climate?

Article

Full-text available

Apr 2022
ECOL APPL

Mountain headwater streams have emerged as important climate refuges for native cold‐water species due to their slow climate velocities and extreme physical conditions that inhibit non‐native invasions. Species persisting in refuges often do so as fragmented, relict populations from broader historical distributions that are subject to ongoing habitat reductions and increasing isolation as climate change progresses. Key for conservation planning is determining where remaining populations will persist and how habitat restoration strategies can improve biological resilience to enhance the long‐term prospects for species of concern. Studying bull trout, a headwater species in the northwestern USA, we developed habitat occupancy models using a data set of population occurrence in 991 natal habitat patches with a suite of novel geospatial covariates derived from high‐resolution hydroclimatic scenarios and other sources representing watershed and instream habitat conditions, patch geometry, disturbance, and biological interactions. The best model correctly predicted bull trout occupancy status in 82.6% of the patches and included effects for: patch size estimated as habitat volume, extent of within‐patch reaches <9°C mean August temperature, distance to nearest occupied patch, road density, invasive brook trout prevalence, patch slope, and frequency of high winter flows. The model was used to assess 16 scenarios of bull trout occurrence within the study streams that represented a range of restoration strategies under three climatic conditions (baseline, moderate change, and extreme change). Results suggested that regional improvements in bull trout status were difficult to achieve in realistic restoration strategies due to the pervasive nature of climate change and the limited extent of restoration actions given their high costs. However, occurrence probabilities in a subset of patches were highly responsive to restoration actions, suggesting that targeted investments to improve the resilience of some populations may be contextually beneficial. A possible strategy, therefore, is focusing effort on responsive populations near more robust population strongholds, thereby contributing to local enclaves where dispersal among populations further enhances resilience. Equally important, strongholds constituted a small numerical percentage of patches (5%–21%), yet encompassed the large majority of occupied habitat by volume (72%–89%) and their protection could have significant conservation benefits for bull trout.

Relating Social and Ecological Resilience: Dutch Citizen’s Initiatives for Biodiversity

Article

Full-text available

Mar 2022

Social resilience and ecological resilience are related and distinguished, and the potential of social resilience to enhance resilience of encompassing social-ecological systems is discussed. The value of resilience thinking is recognized, yet social resilience needs to be better understood in its distinctive qualities, while resisting identification of social resilience with one particular form of governance or organization. Emerging self-organizing citizen’s initiatives in the Netherlands, initiatives involving re-relating to nature in the living environment, are analyzed, using a systems theoretical framework which resists reduction of nature to culture or vice versa. It is argued that space for self-organization needs to be cultivated, that local self-organization and mobilization around themes of nature in daily life and space have the potential to re-link social and ecological systems in a more resilient manner, yet that maintaining the diversity of forms of knowing and organizing in the overall governance system is essential to the maintenance of social resilience and of diverse capacities to know human-environment relations and to reorganize them in an adaptive manner. Conclusions are drawn in the light of the new Biodiversity Strategy.

Movement Patterns of Resident and Translocated Beavers at Multiple Spatiotemporal Scales in Desert Rivers

Article

Full-text available

Mar 2022

Wildlife translocations alter animal movement behavior, so identifying common movement patterns post-translocation will help set expectations about animal behavior in subsequent efforts. American and Eurasian beavers (Castor canadensis; Castor fiber) are frequently translocated for reintroductions, to mitigate human-wildlife conflict, and as an ecosystem restoration tool. However, little is known about movement behavior of translocated beavers post-release, especially in desert rivers with patchy and dynamic resources. We identified space-use patterns of beaver movement behavior after translocation. We translocated and monitored nuisance American beavers in desert river restoration sites on the Price and San Rafael Rivers, Utah, USA, and compared their space use to resident beavers after tracking both across 2 years. Resident adult (RA) beavers were detected at a mean maximum distance of 0.86 ± 0.21 river kilometers (km; ±1 SE), while resident subadult (RS) (11.00 ± 4.24 km), translocated adult (TA) (19.69 ± 3.76 km), and translocated subadult (TS) (21.09 ± 5.54 km) beavers were detected at substantially greater maximum distances. Based on coarse-scale movement models, translocated and RS beavers moved substantially farther from release sites and faster than RA beavers up to 6 months post-release. In contrast, fine-scale movement models using 5-min location intervals showed similar median distance traveled between RA and translocated beavers. Our findings suggest day-to-day activities, such as foraging and resting, were largely unaltered by translocation, but translocated beavers exhibited coarse-scale movement behavior most similar to dispersal by RSs. Coarse-scale movement rates decreased with time since release, suggesting that translocated beavers adjusted to the novel environment over time and eventually settled into a home range similar to RA beavers. Understanding translocated beaver movement behavior in response to a novel desert system can help future beaver-assisted restoration efforts to identify appropriate release sites and strategies.

Beaver: North American Freshwater Climate Action Plan

Preprint

Full-text available

Mar 2022

Rivers and streams, when fully connected to their floodplains, are naturally resilient systems that are increasingly part of the conversation on nature-based climate solutions. Reconnecting waterways to their floodplains improves water quality and quantity, supports biodiversity and sensitive species conservation, increases flood, drought and fire resiliency, and bolsters carbon sequestration. But, while the importance of river restoration is clear, beaver-based restoration - e.g., strategic coexistence, relocation, and mimicry - remains an underutilized strategy despite ample data demonstrating its efficacy.

Beavers and flood alleviation: Human perspectives from downstream communities

Article

Full-text available

Feb 2022

Natural flood management (NFM) methods work with natural processes to reduce flood risk, while often providing additional benefits such as water quality improvement or habitat provision. Increasingly, the activity of an animal—beavers—is recognised to potentially provide flow attenuation, along with multiple benefits for the environment and society, but there can also be associated challenges. We use Q‐Methodology to elicit and understand human perspectives of beavers and their potential role in flood management among communities living downstream of beavers at three sites in England (Cornwall, Yorkshire and the Forest of Dean). This is the first time a study has focused on downstream communities as the primary stakeholders. We identify diverse perspectives that exhibit a range of value judgements. We suggest a catchment‐based approach to beaver management and public engagement may facilitate deeper recognition of contextual perspectives in decision‐making and enable knowledge dissemination with communities. Further, we examine the relationship between beavers and other NFM methods through these perspectives. In doing so we identify features that relate to the unique element of relying on the natural behaviour of beavers for flood management, rather than human flood managers being the primary decision‐makers.

Biogeomorphic influences on river corridor resilience to wildfire disturbances in a mountain stream of the Southern Rockies, USA

Article

Jan 2022
SCI TOTAL ENVIRON

We examine a 9.4-km-long portion of a montane river corridor in the Southern Rockies, the upper 8 km of which burned in 2020. We focus on sediment storage in logjam backwaters and how spatial heterogeneity in the river corridor attenuates downstream fluxes of material following the wildfire. Wider portions of river corridor exhibit greater spatial heterogeneity, as reflected in multithread channel planform and more closely spaced abandoned beaver dams and channel-spanning logjams. Logjams in multithread reaches have greater volumes of backwater storage and store finer sediment than logjams in single-thread reaches. Despite substantial turnover of sediment in backwater storage during the first runoff season after the wildfire, the cumulative volume of sediment stored at 11 monitored logjams following the 2021 runoff season was 71% of the cumulative sediment volume at the logjams immediately after the fire. Floodplain vegetation regrowth was also faster and more complete at multithread reaches. Vegetation recovery contributed to overbank deposition in these reaches, in contrast to the bank erosion observed in single-thread reaches. More spatially heterogeneous portions of the river corridor appear to be disproportionately important in attenuating enhanced inputs of sediment following wildfire, and the cumulative effect of this attenuation across a river network likely enhances watershed-scale resilience to wildfire disturbance.

A national scale floodplain model revealing channel gradient as a key determinant of beaver dam occurrence and inundation potential can anticipate land-use based opportunities and conflicts for river restoration

Article

Full-text available

Nov 2024

The Eurasian beaver (Castor fiber) has expanded its range considerably due to reintroduction and conservation efforts and the species is now found in more than 30 countries across Europe. This expansion brings with it opportunities for nature restoration, the provision of river ecosystem services and the return of naturally functioning floodplains. It also has the potential for conflict with existing human land-use through dam induced floodplain inundation and wetland development. To maximise restoration benefits and minimise conflict, modelling approaches are needed that can predict the likelihood of dam building and include scenarios for subsequent floodplain inundation. This study describes the first national-scale comprehensive study on the drivers of beaver dam occurrence and beaver floodplain inundation potential. This revealed that channel gradient was the overriding driver of both dam occurrence and potential land-use impact. Although widely considered to be a key constraint, channel width exhibited considerably lower explanatory power. The delineation of areas reflecting overall opportunities and conflict reveals that the reintroduction of Castor fiber into Switzerland implies a net benefit from a landscape restoration perspective, though outcomes scaled closely with catchment position. Given the rapidly expanding population range and popularity of continuing beaver reintroductions, this approach could help maximise landscape restoration goals whilst minimising undesirable land-use conflicts that may harm conservation efforts.

Ten steps towards integrated decision making for ecological restoration in cities: Rewilding the European beaver (Castor fiber) in Berlin, Germany

Article

Full-text available

Jun 2024

Ensuring a livable city for all within the more-than-human discourse, restoration of urban ecosystems requires careful consideration of both human and non-human needs. However, traditional assessments and therefore most management plans usually fail to include the latter as a core planning requirement. This article presents and explains a 10-step method which simultaneously and actively considers both to identify potential restoration areas within urban ecosystems. To do so, a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis for the multispecies needs identification is combined with a Multicriteria Spatial Decision Support System (MCSDSS) for the spatial assessment. To validate this method, a case study of Berlin, Germany, an explicitly urban case, is presented. The aim of the study was to evaluate the ecosystem restoration (rewilding) potential of the city's riparian and riverine ecosystems through the enhancement of Eurasian beaver habitats.•Method combining SWOT analysis with MCSDSS for an integrated spatial assessment •Well-suited for multispecies (human and non-human) perspective on urban nature restoration

Ten Steps Towards Integrated Decision Making for Ecological Restoration in Cities: Rewilding the European Beaver (Castor Fiber) in Berlin, Germany

Preprint

Full-text available

Jan 2024

The host-specific parasitic beaver beetle Platypsyllus castoris. p94 IN: Brazier, R.E., Elliott, M., Andison, E., Auster, R.E., Bridgewater, S., Burgess, P., Chant, J., Graham, H., Knott, E., Puttock, A.K., Sansum, P., Vowles, A., (2020) River Otter Beaver Trial: Science and Evidence Report. pp132. Devon Wildlife Trust. https://www.flipsnack.com/devonwildlifetrust/river-otter-beaver-trial-science-and-evidence-report.html

Article

Apr 2020

Clive Richard Turner

A bibliometric literature review in beaver management: when does the beaver become a resource?

Article

Dec 2023

Freshwater ecosystems are some of the most biodiverse habitats, but they are among the most endangered due to human activities. In this context, beavers represent a nature‐based solutions to preserve and repair freshwater ecosystem, given their important role as ecosystem engineers. However, in an environment modified by humans, beaver activities frequently create conflicts masking the positive effects of this rodent. Therefore, the management of beaver populations and human–beaver conflicts is needed. This article investigates the literature about beaver management through a bibliometric analysis to understand past, current, and future response. Moreover, it quantifies the number of studies that consider beavers as a resource, and it identifies the emerging themes in the field. The bibliometric analysis was performed considering a total of 415 documents with the software VOSviewer and the R web interface for bibliometrix Biblioshiny. The analysis presented here provides a complete view of past, present, and future management approaches and responses at the base of beaver management strategies. Three main results emerged. Firstly, a rising tendency in the number of publications about beavers that are directly linked to the populations development and spread has detected. Secondly, only 4.3% of scientific literature has referred to beaver‐related restoration. Thirdly, the ‘human perceptions’ has resulted in the emerging field investigated. Findings suggest that there is a lot of research interest about beaver management. The beaver is still poorly managed as a tool for freshwater ecosystem restoration. The management is shifting from studies focused more so on beaver ecology to others mainly focused on the beaver effects and the human dimension. This review provides a starting point for future research on beavers and suggests the development of socio‐ecological management models that consider benefits and impacts of beavers. This will help the decision‐making process of conservation and restoration initiatives.

Human-beaver cohabitation in the Early and Mid-Holocene of Northern Europe: Re-visiting Mesolithic material culture and ecology through a multispecies lens

Article

Full-text available

Oct 2023
HOLOCENE

The Eurasian beaver (Castor fiber) was an important member of Early and Mid-Holocene landscapes and animal communities in Northern Europe. Previous zooarchaeological research has established the alimentary roles of beavers for Mesolithic societies and their importance for fur procurement. In this paper, we develop an integrated biocultural approach to human-beaver interactions, examining the position of humans and beavers in Mesolithic and Early Neolithic multispecies systems. We contextualize beaver landscape agency in hydroactive environments with human behaviour, synthesizing currently available data on mammalian assemblages, ichtyofauna and beaver-related material culture across Northern Europe. This cross-cultural, diachronic analysis reveals previously overlooked facilitations of human behaviour by beaver practices and ecological legacies. We show that long-term trajectories of human-beaver cohabitation differed between northern European regions. While in Southern Scandinavia, human-beaver intersections witnessed major re-organizations during the Mid-Holocene, beavers retained a key role for human societies across Northeastern Europe throughout much of the Holocene and played an important part at the Mesolithic-Neolithic transition in the Dutch wetlands. Divergent pathways are also evidenced by Mesolithic beaver-related material culture, highlighting the cultural keystone status of Castor fiber in higher latitude European landscapes. We argue that this keystone status is grounded in the supply of human hunting, fishing, and gathering affordances by the animals, pointing to the generative commensality between Mesolithic foragers and their beaver neighbours. Taken together, our findings demonstrate the importance of the beaver in the making of Early and Mid-Holocene forager societies in Northern Europe and illustrate the fruitfulness of deploying an integrated multispecies approach.

Distribution of Willows Along Streambanks of Publicly Managed Streams in the Interior Pacific Northwest

Article

Full-text available

Sep 2023
RANGELAND ECOL MANAG

Willows are an important component of western riparian zones as their roots stabilize streambanks, their overstory mediates stream temperature, and aquatic biota use their stems and leaves as forage and build- ing material. We evaluated 1894 stream reaches in the Inland Pacific Northwest for the presence of wil- lows and detected one or more willow species at 1 247 (66%) of those reaches. Most stream reaches where willow was present had two or more willow species. We identified 23 unique species, of which 11 were found in 50 or more stream reaches. Across all sites, stream reaches with willow were more likely to be in the southern high-elevation portion of the study area. Distribution models constructed using random forests included a measure of spatial location (latitude, longitude, elevation) as one of the top predictors for 10 of the 11 common species. Only one species included a stream reach-scale attribute (bankfull stream width) as a top predictor, although two species had gradient or percent of the reach forested as a secondary predictor. While spatial location within the study area was a key factor in deter- mining species presence, differences among species resulted in willows being found across the range of landscape and stream reach conditions except where forest cover in the reach was high ( > 75%). Given that willows share characteristics such as rapid root growth, rhizomes, flexible stems, and vegetative re- production, in many situations different species may respond as functional equivalents when it comes to protecting streambanks, providing habitat for fish and wildlife, and promoting stream heterogeneity. Ongoing threats to willows near streams on public lands include grazing, water diversion, mining, and climate change. Each of these threats can be at least partially addressed by identifying stream reaches inhabited by willow and establishing reach-scale management objectives for this taxon.

Idaho's Floodplain Cottonwood Forests: Extent and Condition of Current and Future Habitat-Implications for Conservation and Restoration

Technical Report

Full-text available

Dec 2019

Idaho's large-river floodplain and riparian forests, especially those dominated by cottonwood (Populus spp.), are crucial ecosystems highly threatened by human land uses and hydrologic shifts resulting from climate change. Once widespread in river valleys of Idaho, the condition, function, and extent of cottonwood riparian and floodplain forests have been greatly diminished. However, prior to this project, no assessment of the conservation status of this ecosystem existed. Goals of this project were to: • describe the distribution and condition of floodplain cottonwood forests in Idaho • analyze potential climate change impacts on the long-term viability of this ecosystem • develop conservation and restoration strategies that incorporate climate change adaptation and resilience concepts We used Maxent to model the current and future extent and distribution of cottonwood habitat using species observations, climate variables, and abiotic predictors. Future habitat was predicted with Maxent by using climate variables modeled for mid-century RCP 4.5 and RCP 8.5 emissions scenarios. The condition of current and future suitable cottonwood habitat occurring in river and large stream valley bottoms was analyzed by applying an existing landscape integrity map. A watershed-scale Flow Modification Index, based on water and land use, was created to characterize the degree of departure from the natural hydrologic regime in each watershed. The flow modification index was applied to predicted current and future habitat to assess constraints on cottonwood sustainability. The potential effects of projected climate induced river flow changes on cottonwood reproduction were also explored. These analyses were then used to develop watershed and river reach-specific conservation and restoration strategies for floodplains predicted to have higher long-term viability for cottonwoods.

American Beaver (Castor canadensis) Dam-and Pond Surveys at Daly Creek Habitat Management Area, 2009-2018

Technical Report

Full-text available

Jan 2019

Anthonie M. A. Holthuijzen

Historically, beavers and beaver dams were an important component of dryland riparian systems in the western US and exerted an extraordinary influence on these systems. At the time of Euroamerican settlement of the Eagle Valley, beavers were present along main Daly Creek. Land management activities including diverting water for irrigation, channelizing, and removal of riparian vegetation for agricultural purposes and cattle grazing likely changed the historic multi-thread channel system at Daly Creek into a single-thread channel. Daly Creek was divided in 3 reaches based on past legacy of farming and grazing to evaluate system responses: 1) Lower Daly Creek (1.2 miles [1.9 km]), 2) Middle Daly Creek (5.9 miles [9.5 km]), and 3) Upper Daly Creek (2 miles [3.2 km]). Given the key role that beaver play in the recovery of Daly Creek, beaver dam and pond surveys started in 2009 when beaver activity was first noted as part of a larger study to assess (passive) riparian recovery. Specific objectives were to: 1) annually locate all beaver dams, 2) collect information on location, and physical characteristics of dams (i.e., dam height and length, crossing of stream or partial dam), and 3) survey and map beaver ponds on at least a 2-year interval. From 2009 through 2018, surveys were conducted annually, although no beaver activity was noted in 2010-2012. In 2009, 2013 and 2014 spring surveys were conducted. In 2014 and following years, fall surveys were conducted when beaver dam numbers peak during low base flows. Beaver ponds were surveyed in 2015 and 2018. Turn-over rates of dams was high, based on new dams constructed annually (𝑥̅=70.7±26.0(STD)%). Number of dams increased quadratically along the Middle Reach (pre-existing and new) from 8 in 2008 to 56 in 2018. Dam densities along the Middle Reach ranged from 0.5 to 5.2 dams/km. Overall, 63.5% of all beaver dams crossed the stream. Average length of a dam was 7.5±6.8(1 STD) m, ranging from 2.25 to 40.0 m and did not differ among reaches. Average height of a dam was 0.96±0.40(1 STD) m, ranging from 0.10 to 2.0 m and was similar among reaches. Ponds averaged 0.05±0.05(1 STD) acres and .13±0.19(1 STD) acres and in 2015 and 2018, respectively, with 9.3% overlap. Location of eaver dam complexes shifted over time. Beaver dams concentrated in the Lower Reach in 2009. The Middle Reach was consistently occupied from 2013 through 2018 and the lower part of the Upper reach in 2015, 2017, and 2018. Sections of the Middle Reach where beaver dams and ponds became established changed from single-thread stream (12% functional) to a sinuous streambed (45-67% functional) between 2007 and 2018. In 2018, there was limited in-channel features and vegetation recovery, and the channel likely reconnected to groundwater and hyporheic zones. Vegetation and floodplain- and hyporheic connectivity may afford moderate flood and drought resilience; furthermore, water clarity and stream temperature amelioration continued to improve. Absence of beavers in the Upper Reach and continued livestock grazing impaired streambed and woody riparian recovery, effectively stalling improvement of the Upper Reach, where the streambed remains a single-thread stream (12% functional). The Lower Reach remained in stasis (12% functional), as beavers did no successfully colonize this reach, because food remained limited for beavers, spring flows removed beaver dams, and beavers were likely highly susceptible to predation in this narrow, incised stream. In the absence of beaver dams and other structures, such as log jams, there is little opportunity for the retention of sediments, aggradation of the stream bed, and recovery from a single-thread to a multi-thread, or sinuous stream bed

Comparing translocated beavers used as passive restoration tools to resident beavers in degraded desert rivers

Article

Full-text available

Dec 2022
ANIM CONSERV

Wildlife translocation facilitates conservation efforts, including recovering imperiled species, reducing human–wildlife conflict, and restoring degraded ecosystems. Beaver (American, Castor canadensis; Eurasian, C. fiber) translocation may mitigate human–wildlife conflict and facilitate ecosystem restoration. However, few projects measure outcomes of translocations by monitoring beaver postrelease, and translocation to desert streams is relatively rare. We captured, tagged, and monitored 47 American beavers (hereafter, beavers) which we then translocated to two desert rivers in Utah, USA, to assist in passive river restoration. We compared translocated beaver site fidelity, survival, and dam‐building behavior to 24 resident beavers. We observed high apparent survival (i.e., survived and stayed in the study site) for eight weeks postrelease of resident adult beavers (0.88 ± 0.08; standard error) and lower but similar apparent survival rates between resident subadult (0.15 ± 0.15), translocated adult (0.26 ± 0.12), and translocated subadult beavers (0.09 ± 0.08). Neither the pre‐ nor the post‐translocation count of river reaches with beaver dams were predicted well by the Beaver Restoration Assessment Tool, which estimates maximum beaver dam capacity by river reach, suggesting beaver‐related restoration is not maximized in these rivers. Translocated beavers exhibited similar characteristics as resident subadult beavers during dispersal; they were more vulnerable to predation and many emigrated from the study sites. High mortality and low site fidelity should be anticipated when translocating beavers, but even so, translocation may have contributed to additional beaver dams in the restoration sites, which is the common goal of beaver‐assisted river restoration. Multiple releases at targeted restoration sites may eventually result in establishment and meet conservation objectives for desert rivers.

Conceptualising multispecies collaboration: Work, animal labour, and Nature‐based Solutions

Article

Dec 2022

E. A. Welden

Tracing the story of beaver restoration across California, this paper investigates the emerging discourse of ‘working with nature’ through the lens of animal work and labour, exploring possibilities for, and conceptualising, multispecies collaboration. At the intersection of animal geographies, environmental anthropology, and geographies of conservation, this paper finds three concurrent modes of working with beaver: beaver as labourer, beaver as coworker, and beaver as community. Beaver as labourer emerges as a mode where beavers go from material resource to low‐wage labourer, their liveliness predicated on their ability to be working for humans. Beaver as coworker transitions beavers from labourers to workers, respected for their skills as ecosystem engineers to be working with. Beaver as community emerged as a mode in which beavers and humans live with each other as kin, amidst wider multispecies assemblages. This mode sets the foundation to theorise the concept of multispecies collaboration, a term often used in the literature, but never defined. This paper explores the concept through theories of animal work and labour, challenging the premise of work altogether, while situating multispecies collaboration as an in‐between, a both/and space of working and living with ‘nature.’ This paper serves as an important reflection on the ways in which humans ‘work with nature,’ in a time where various nonhumans are being made to be ‘workers.’ It presents and analyses these relations, ruminates on implications for governance of these multispecies spaces, and develops the concept of multispecies collaboration as a critical consideration for Nature‐based Solutions.

North Fork Sprague River: Bailey Flat Riverscape Restoration

Technical Report

Full-text available

Dec 2021

Gus Wathen

As-built report for Phase 1 of the Bailey Flat Low-tech Process-based Riverscape Restoration.

2D Modeling and Ecohydraulic Analysis

Book

Full-text available

Jan 2011

Gregory Brian Pasternack

The River Discontinuum: Applying Beaver Modifications to Baseline Conditions for Restoration of Forested Headwaters

Article

Full-text available

Dec 2010

Billions of dollars are being spent in the United States to restore rivers to a desired, yet often unknown, reference condition. In lieu of a known reference, practitioners typically assume the paradigm of a connected watercourse. Geological and ecological processes, however, create patchy and discontinuous fluvial systems. One of these processes, dam building by North American beavers (Castor canadensis), generated discontinuities throughout precolonial river systems of northern North America. Under modern conditions, beaver dams create dynamic sequences of ponds and wet meadows among free-flowing segments. One beaver impoundment alone can exceed 1000 meters along the river, flood the valley laterally, and fundamentally alter biogeochemical cycles and ecological structures. In this article, we use hierarchical patch dynamics to investigate beaver-mediated discontinuity across spatial and temporal scales. We then use this conceptual model to generate testable hypotheses addressing channel geomorphology, natural flow regime, water quality, and biota, given the importance of these factors in river restoration.

Modeling the Capacity of Riverscapes to Support Dam-Building Beaver : Case Study - Escalante River Watershed

Technical Report

Full-text available

Jan 2013

Beaver (Castor canadensis) dam-building activities lead to a cascade of hydrologic, geomorphic and ecological effects that increase stream complexity, which benefits a wide-variety of aquatic and terrestrial species. Depending on biophysical and vegetation conditions present, beaver dam-building activities variously trap sediment; raise incised streambeds, often reconnecting them with their floodplains; subirrigate the valley downstream of a dam; create wetlands; slow runoff; mitigate impacts by floods; extend seasonal stream flow; increase stream complexity; extend riparian woody and other vegetation; and create or increase habitat for diverse and sometimes rare species, including amphibians, fish, small mammals, and birds. As a result, beaver are increasingly being used as a critical component of passive stream and riparian restoration strategies.

Impacts of beaver dams on hydrologic and temperature regimes in a mountain stream

Article

Full-text available

Aug 2015

Beaver dams affect hydrologic processes, channel complexity, and stream temperature in part by inundating riparian areas, influencing groundwater–surface water interactions, and changing fluvial processes within stream systems. We explored the impacts of beaver dams on hydrologic and temperature regimes at different spatial and temporal scales within a mountain stream in northern Utah over a 3-year period spanning pre- and post-beaver colonization. Using continuous stream discharge, stream temperature, synoptic tracer experiments, and groundwater elevation measurements, we documented pre-beaver conditions in the first year of the study. In the second year, we captured the initial effects of three beaver dams, while the third year included the effects of ten dams. After beaver colonization, reach-scale (~ 750 m in length) discharge observations showed a shift from slightly losing to gaining. However, at the smaller sub-reach scale (ranging from 56 to 185 m in length), the discharge gains and losses increased in variability due to more complex flow pathways with beaver dams forcing overland flow, increasing surface and subsurface storage, and increasing groundwater elevations. At the reach scale, temperatures were found to increase by 0.38 °C (3.8 %), which in part is explained by a 230 % increase in mean reach residence time. At the smallest, beaver dam scale (including upstream ponded area, beaver dam structure, and immediate downstream section), there were notable increases in the thermal heterogeneity where warmer and cooler niches were created. Through the quantification of hydrologic and thermal changes at different spatial and temporal scales, we document increased variability during post-beaver colonization and highlight the need to understand the impacts of beaver dams on stream ecosystems and their potential role in stream restoration.

Spring Creek Wetland Area Adaptive Beaver Management Plan

Technical Report

Full-text available

Jan 2015

Survival, fates, and success of transplanted Beavers, Castor canadensis, in Wyoming

Article

Full-text available

Jan 2002
Can Field Nat

Beaver (Castor canadensis) through their dam building activities, store water, trap sediment, subirrigate vegetation, and subsequently improve habitat for fish, wildlife, and livestock. Many landowners realize the benefits that Beaver can bring to a riparian area and are interested in using them to improve this habitat. From 1994 to 1999 we trapped and relocated 234 Beaver to 14 areas throughout Wyoming to improve riparian habitat and create natural wetlands. We attached radio transmitters to 114 Beaver and subsequently determined movements and mortality of released Beaver, and the overall success of our releases. Mortality and emigration (including transmitter failure) accounted for the loss of 30% and 51%, respectively, of telemetered Beaver within 6 months of release. Kaplan-Meier survival estimates were 0.49 (SE = 0.068) for 180 days and 0.433 (SE = 0.084) for 360 days, and did not differ significantly between age classes. On average, 17 Beaver were transplanted to each release site, and at 11 locations, in an attempt to augment single Beaver that had become established and increase transplant success, we transplanted Beaver in two or more years. Success of an individual Beaver's relocation was unrelated to any of the variables we tested, although 2-3.5 year-old Beaver had higher average success (measured in days of occupancy at the release site) than older animals. Animals < 2 years old had 100% mortality and emigration losses within 6 months of release. High predation and mortality rates of our released Beaver may be due to habitat (our streams were shallow with no ponds and provided little protection) and extensive predator communities. We established Beaver at 13/14 of our release sites and they eventually reproduced. Our results show that Beaver can be relocated successfully but losses from mortality and emigration need to be considered and planned for.

Impacts of beaver dams on hydrologic and temperature regimes in a mountain stream

Article

Full-text available

Jan 2015
HESSD

Beaver dams affect hydrologic processes, channel complexity, and stream temperature by increasing inundated areas and influencing groundwater-surface water interactions. We explored the impacts of beaver dams on hydrologic and temperature regimes at different spatial and temporal scales within a mountain stream in northern Utah over a three-year period spanning pre- and post-beaver colonization. Using continuous stream discharge, stream temperature, synoptic tracer experiments, and groundwater elevation measurements we documented pre-beaver conditions in the first year of the study. In the second year, we captured the initial effects of three beaver dams, while the third year included the effects of ten dams. After beaver colonization, reach scale discharge observations showed a shift from slightly losing to gaining. However, at the smaller sub-reach scale, the discharge gains and losses increased in variability due to more complex flow pathways with beaver dams forcing overland flow and increasing surface and subsurface storage. At the reach scale, temperatures were found to increase by 0.38 °C (3.8%), which in part is explained by a 230% increase in mean reach residence time. At the smallest, beaver dam scale, there were notable increases in the thermal heterogeneity where warmer and cooler niches were created. Through the quantification of hydrologic and thermal changes at different spatial and temporal scales, we document increased variability during post-beaver colonization and highlight the need to understand the impacts of beaver dams on stream ecosystems and their potential role in stream restoration.

Pine Creek Watershed Scoping Plan for Restoration: Using Beaver Dam Analogs and High-Density LWD to Initiate Process-Based Stream Recovery

Technical Report

Full-text available

Feb 2015

This report was contracted by the Confederated Tribes of Warm Springs to inventory the existing geomorphic conditions and recovery potential of the Pine Creek Watershed, and to lay out a strategic plan for restoration actions that will inform a later detailed design plan. The report presents the results of a hydrologic and geomorphic assessment undertaken using a simplified version of the River Styles framework (Brierley and Fryirs, 2005). This data informed the condition and recovery potential assessment presented herein. Additionally we present the results of a BRAT (beaver restoration assessment tool: http://brat.joewheaton.org) analysis which assessed existing and potential beaver dam building capacities in the Pine Creek Watershed. This information was synthesized into the strategic restoration plan, which is a simple and cost-effective treatment that seeks to partner with a small extant beaver population to restore geomorphic, hydrologic and ecological processes to improve habitat for aquatic and riparian biota within the incised portions of lower Pine Creek. Beaver Dam Analogues (BDAs) and High-Density Large Woody Debris (HDLWD) structures will be used to produce many of the same benefits as natural beaver dams and achieve additional restoration objectives (e.g., provide stable locations for beaver to establish persistent complexes, restore surface water connectivity, etc.). The strategic restoration plan is not a detailed design plan but provides recommendations for restoration objectives, priorities and reach types throughout the mainstem of Pine Creek. Finally, recommendations are provided on maintaining restoration structures and complexes within an adaptive management framework.

Landscape-scale carbon storage associated with beaver dams

Article

Full-text available

Jul 2013

Ellen Wohl

[1] Beaver meadows form when beaver dams promote prolonged overbank flooding and floodplain retention of sediment and organic matter. Extensive beaver meadows form in broad, low-gradient valley segments upstream from glacial terminal moraines. Surveyed sediment volume and total organic carbon content in beaver meadows on the eastern side of Rocky Mountain National Park are extrapolated to create a first-order approximation of landscape-scale carbon storage in these meadows relative to adjacent uplands. Differences in total organic carbon between abandoned and active beaver meadows suggest that valley-bottom carbon storage has declined substantially as beaver have disappeared and meadows have dried. Relict beaver meadows represent ~8% of total carbon storage within the landscape, but the value was closer to 23% when beaver actively maintained wet meadows. These changes reflect the general magnitude of cumulative effects in heterotrophic respiration and organic matter oxidation associated with historical declines in beaver populations across the continent.

A Stream Habitat Classification System for Beaver

Article

Full-text available

Jan 1985

Documentation over a 28-year period of beaver (Castor canadensis) habitat use permitted development and testing of two models to predict maximum density of active beaver colonies on streams. Principal components regression, a technique that reduced the confounding effects of closely correlated ecological variables found in earlier studies of this type, and discriminant analysis were used for model development. In mixed coniferous-deciduous forest habitat, the percentage of hardwood vegetation, watershed size, and stream width had significant positive effects on active colony density. Increasing stream gradient and progressively well-drained soils had negative effects. In field-tests, the models were 80% and 75% reliable in predicting active colony density.

Site-Occupancy Monitoring Of An Ecosystem Indicator: Linking Characteristics Of Riparian Vegetation To Beaver Occurrence

Article

Full-text available

Dec 2012

Establishment of sampling frameworks to monitor the occurrence of ecological indicators and to identify the covariates that influence occurrence is a high-priority need for natural resource restoration and management efforts. We utilized occupancy modeling to identify patterns of beaver occurrence and factors influencing these patterns (i.e., type and amount of vegetation cover) in the Grand Canyon of the Colorado River ecosystem. We used rafts and kayaks to access a stratified random sample of sites (i.e., 100-m-long sections of riverbank) and used repeated sampling procedures to sample for beaver sign (i.e., lodges, cuttings, tracks, and beaver sightings). We quantified the type and amount of vegetation cover at each sampled section by using a GIS database of remotely sensed information on the riparian vegetation in the Grand Canyon. We first modeled occurrence of beaver sign as a function of the total amount of vegetation cover (summed across classes) and then determined the relative importance score for each of the 7 vegetation classes. Detection probability (p) was 2 times higher when observers traveled in kayaks (0.61) than when they traveled in rafts (0.29). Occurrence of beaver sign (ψ) in sampled transects was widespread throughout the Grand Canyon (ψ = 0.74, SE = 0.06) and positively associated with total vegetation. The relative importance scores for Tamarix and Pluchea vegetation classes were 1.5–2.5 times larger than those for all other vegetation classes, indicating that occurrence of beaver sign was most strongly associated with the cover of these 2 vegetation classes. Our results imply that quantifying the amount of riparian vegetation in close proximity to a river helps determine the occurrence of an important ecological indicator in riparian systems. The results also demonstrate a useful and cost-effective method for monitoring riverine species' usage patterns by explicitly accounting for detectability.

The Utah Beaver Restoration Assessment Tool: A Decision Support & Planning Tool

Technical Report

Full-text available

Oct 2014

Problematizing Beaver Habitat Identification Models for Reintroduction Application in the Western United States

Article

Full-text available

Jan 2013
Yearbk Assoc Pac Coast Geogr

Jeff Baldwin

Due to the beaver’s former role as a ubiquitous keystone species, there are increasing efforts in the American West to assist beaver in recolonization. Many interested in reintroduction are using two methods to identify optimal habitat: habitat suitability indexes/models (HSI), and historic occupation. This study details some of the problems inherent in HSIs applied to beaver habitat. The paper then interrogates historical occupation as a relocation tool, and finds that while more logically consistent, this method of habitat identification is also problematic. Historic range does not integrate past or present causes of extirpation and absence. I argue that, specifically in the case of beaver relocation but potentially for other species as well, causes of mortality are as important as are environmental amenities in identifying appropriate habitat.

Ecology, management, and conservation implications of North American beaver (Castor canadensis) in dryland streams

Article

Full-text available

Jun 2014
AQUAT CONSERV

After near‐extirpation in the early 20th century, beaver populations are increasing throughout many parts of North America. Simultaneously, there is an emerging interest in employing beaver activity for stream restoration in arid and semi‐arid environments (collectively, ‘drylands’), where streams and adjacent riparian ecosystems are expected to face heightened challenges from climate change and human population growth. Despite growing interest in reintroduction programmes, surprisingly little is known about the ecology of beaver in dryland streams, and science to guide management decisions is often fragmented and incomplete. This paper reviews the literature addressing the ecological effects and management of beaver activity in drylands of North America, highlighting conservation implications, distinctions between temperate and dryland streams, and knowledge gaps. Well‐documented effects of beaver activity in drylands include changes to channel morphology and groundwater processes, creation of perennial wetland habitat, and substantial impacts to riparian vegetation. However, many hypothesized effects derived from temperate streams lack empirical evidence from dryland streams. Topics urgently in need of further study include the distribution and local density of beaver dams; consequences of beaver dams for hydrology and water budgets; and effects of beaver activity on the spread of aquatic and riparian non‐native species. In summary, this review suggests that beaver activity can create substantial benefits and costs for conservation. Where active beaver introductions or removals are proposed, managers and conservation organizations are urged to implement monitoring programmes and consider the full range of possible ecological effects and trade‐offs. Copyright © 2014 John Wiley & Sons, Ltd.

Effects of Flooding and Tamarisk Removal on Habitat for Sensitive Fish Species in the San Rafael River, Utah: Implications for Fish Habitat Enhancement and Future Restoration Efforts

Article

Full-text available

Jul 2014

Tamarisk removal is a widespread restoration practice on rivers in the southwestern USA, but impacts of removal on fish habitat have rarely been investigated. We examined whether tamarisk removal, in combination with a large spring flood, had the potential to improve fish habitat on the San Rafael River in southeastern Utah. We quantified habitat complexity and the distribution of wood accumulation in a tamarisk removal site (treated) and a non-removal site (untreated) in 2010, 1 year prior to a large magnitude and long-duration spring flood. We used aerial imagery to analyze river changes in the treated and untreated sites. Areas of channel movement were significantly larger in the treated site compared to the untreated site, primarily because of geomorphic characteristics of the channel, including higher sinuosity and the presence of an ephemeral tributary. However, results suggest that tamarisk removal on the outside of meander bends, where it grows directly on the channel margins, can promote increased channel movement. Prior to the flood, wood accumulations were concentrated in sections of channel where tamarisk had been removed. Pools, riffles, and backwaters occurred more frequently within 30 m upstream and downstream of wood accumulations compared to areas within 30 m of random points. Pools associated with wood accumulations were also significantly larger and deeper than those associated with random points. These results suggest that the combination of tamarisk removal and wood input can increase the potential for channel movement during spring floods thereby diversifying river habitat and improving conditions for native fish.

Direct and indirect drivers of instream wood in the interior Pacific Northwest, USA: Decoupling climate, vegetation, disturbance, and geomorphic setting

Article

Full-text available

Jun 2014

Instream wood is a driver of geomorphic change in low-order streams, frequently altering morphodynamic processes. Instream wood is a frequently measured component of streams, yet it is a complex metric, responding to ecological and geomorphic forcings at a variety of scales. Here we seek to disentangle the relative importance of physical and biological processes that drive wood growth and delivery to streams across broad spatial extents. In so doing, we ask two primary questions: (1) is riparian vegetation a composite variable that captures the indirect effects of climate and disturbance on instream wood dynamics? (2) What are the direct and indirect relationships between geomorphic setting, vegetation, climate, disturbance, and instream wood dynamics? We measured riparian vegetation composition and wood frequency and volume at 720 headwater reaches within the American interior Pacific Northwest. We used ordination to identify relationships between vegetation and environmental attributes, and subsequently built a structural equation model to identify how climate and disturbance directly affect vegetation composition and how vegetation and geomorphic setting directly affect instream wood volume and frequency. We found that large wood volume and frequency are directly driven by vegetation composition and positively correlated to wildfire, elevation, stream gradient, and channel bankfull width. Indicator species at reaches with high volumes of wood were generally long-lived, conifer trees that persist for extended durations once delivered to stream habitats. Wood dynamics were also indirectly mediated by factors that shape vegetation: wildfire, precipitation, elevation, and temperature. We conclude that wood volume and frequency are driven by multiple interrelated climatic, geomorphic, and ecological variables. Vegetation composition and geomorphic setting directly mediate indirect relationships between landscape environmental processes and instream large wood. Where climate or geomorphic setting preclude tree establishment, reaches may remain naturally depauperate of instream wood unless wood is transported from elsewhere in the stream network.

Do Beaver Dams Impede the Movement of Trout?

Article

Full-text available

Jul 2013

Dams created by North American beavers Castor canadensis (hereafter, “beavers”) have numerous effects on stream habitat use by trout. Many of these changes to the stream are seen as positive, and many stream restoration projects seek either to reintroduce beavers or to mimic the habitat that they create. The extent to which beaver dams act as movement barriers to salmonids and whether successful dam passage differs among species are topics of frequent speculation and warrant further research. We investigated beaver dam passage by three trout species in two northern Utah streams. We captured 1,375 trout above and below 21 beaver dams and fitted them with PIT tags to establish whether fish passed the dams and to identify downstream and upstream passage; 187 individual trout were observed to make 481 passes of the 21 beaver dams. Native Bonneville Cutthroat Trout Oncorhynchus clarkii utah passed dams more frequently than nonnative Brown Trout Salmo trutta and nonnative Brook Trout Salvelinus fontinalis. We determined that spawn timing affected seasonal changes in dam passage for each species. Physical characteristics of dams, such as height and upstream location, affected the passage of each species. Movement behaviors of each trout species were also evaluated to help explain the observed patterns of dam passage. Our results suggest that beaver dams are not acting as movement barriers for Bonneville Cutthroat Trout or Brook Trout but may be impeding the movements of invasive Brown Trout.Received November 26, 2012; accepted April 15, 2013

Dam-site selection by beavers in an eastern Oregon basin

Article

Full-text available

Jan 1990

We compared physical and vegetative habitat characteristics at 14 dam sites occupied by beaver (Castor canadensis) with those at 41 random unoccupied reaches to identiiy features important to dam-site selection in the Long Creek basin, Grant County, Oregon. Stream reaches with dams were shallower and had a lower gradient than unoccupied reaches. Beaver did not build dams at sites with a rock substrate. Bank slopes at occupied reaches were not as steep as those at unoccupied reaches; and occupied stream reaches had greater tree canopy cover, especially of thinleaf alder (Alnus tenuifolia), than did unused reaches. A discriminant model using transformations of bank slope, stream gradient, and hardwood cover classified all beaver dam sites correctly and 35 of 41 random sites as unoccupied sites. The 6 misclassified sites had rock substrates. We also tested four habitat suitability models for beaver in this basin. Three models produced significantly different (P < .05) scores between occupied and random unoccupied reaches, suggesting that they might have some utility for this region.

Habitat and Structural Factors Influencing Beaver Interference with Highway Culverts

Article

Full-text available

Jun 2001

The plugging of highway culverts by beavers (Castor canadensis) creates roadside impoundments that damage and sometimes flood the roadbed. Continually mitigating these problem sites requires considerable time, money, and resources from town, county, and state highway departments. We initiated this study to develop proactive and longterm approaches to deal with nuisance beavers along roadsides. Our specific objective was to compare culvert and habitat features at plugged and nonplugged culverts. From June to October 1997 and 1998, we sampled 216 roadside sites in New York state: 113 sites where beavers plugged the highway culvert and 103 sites where beavers did not plug the culvert but instead constructed an upstream or downstream dam. We used stepwise logistic regression (SLR) to identify key variables associated with plugged culverts. We evaluated classification rates of regression models with measures of sensitivity and specificity. For the combined data set, the logistic function retained culvert inlet opening area

({\rm m}^{2})

and stream gradient in the final model. Based on these 2 variables, the model correctly classified 79% of the sites. Our results indicated that installing oversized culverts would have the greatest influence on discouraging beaver plugging activity. Prorated over the service life of culverts, the installation of oversized culverts by highway departments may be more cost-effective than trapping, debris removal, or other short-term options to manage beaver damage to roads.

Using Beaver Dams to Restore Incised Stream Ecosystems

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Mar 2014
BIOSCIENCE

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.

Riparian vegetation communities change rapidly following passive restoration at a northern Utah stream

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Jul 2013
ECOL ENG

Riparian vegetation may recover quickly from disturbance when the disturbance vector is removed or reduced. Grazing is a disturbance that removes plant biomass through herbivory, while overgrazing is a more severe disturbance that can deplete plant propagule pools and inhibit plant community recovery. We tested the hypothesis that riparian vegetation communities can shift quickly from ruderal grasslands to hydrophytic shrubs and graminoids when grazing is largely eliminated from riparian areas. We used a before-after-control study design to collect vegetation community data at six restored reaches and two grazed control reaches prior to and immediately following the construction of a cattle exclosure. We identified trends in Carex and Salix species abundance and quantified shifts in riparian vegetation community composition across time at each reach using PERMANOVA, multi-level pattern analysis and non-metric multidimensional scaling. Vegetation composition changed rapidly in the four years following removal of grazing disturbance. Indicator species for all impact reaches shifted away from grazing tolerant graminoids and forbs, and toward hydrophytic graminoid and shrub species. Over the same timespan control reach indicator species remained grazing-tolerant graminoids and forbs. There was little change in Salix abundance over time at control or impact reaches but Carex abundance increased at restored reaches. We conclude that herbaceous plant communities may recover rapidly following the removal of grazing disturbance, but that woody species may lag in recovery without active vegetation manipulation. We postulate that low woody-species recruitment may affect the potential of the riparian zone to quickly shade stream channels and facilitate undercut bank formation, common riparian restoration objectives. To prevent halted riparian succession, designers should proactively identify potential limitations to woody vegetation colonization. We close discussing active approaches to overcome stalled riparian ecosystem development and suggest metrics for assessing woody species recovery. Includes supplemental file.

Working with Beaver to Restore Salmon Habitat in the Bridge Creek Intensively Monitored Watershed-Design Rationale and Hypotheses.

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Jan 2012

Natural and historical variability in fluvial processes, beaver activity, and climate in the Greater Yellowstone Ecosystem

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Jun 2013
EARTH SURF PROC LAND

Two centuries of human activities in the Greater Yellowstone Ecosystem (GYE) have strongly influenced beaver activity on small streams, raising questions about the suitability of the historical (Euro-American) period for establishing stream reference conditions. We used beaver-pond deposits as proxy records of beaver occupation to compare historical beaver activity to that throughout the Holocene. Forty-nine carbon-14 (14C) ages on beaver-pond deposits from Grand Teton National Park indicate that beaver activity was episodic, where multi-century periods lacking dated beaver-pond deposits have similar timing to those previously documented in Yellowstone National Park. These gaps in the sequence of dated deposits coincide with episodes of severe, prolonged drought, e.g. within the Medieval Climatic Anomaly 1000–600 cal yr bp, when small streams likely became ephemeral. In contrast, many beaver-pond deposits date to 500–100 cal yr bp, corresponding to the colder, effectively wetter Little Ice Age. Abundant historical beaver activity in the early 1900s is coincident with a climate cooler and wetter than present and more abundant willow and aspen, but also regulation of beaver trapping and the removal of wolves (the beaver's main predator), all favorable for expanded beaver populations. Reduced beaver populations after the 1920s, particularly in the northern Yellowstone winter range, are in part a response to elk overbrowsing of willow and aspen that later stemmed from wolf extirpation. Beaver populations on small streams were also impacted by low streamflows during severe droughts in the 1930s and late 1980s to present. Thus, both abundant beaver in the 1920s and reduced beaver activity at present reflect the combined influence of management practices and climate, and underscore the limitations of the early historical period for defining reference conditions. The Holocene record of beaver activity prior to Euro-American activities provides a better indication of the natural range of variability in beaver-influenced small stream systems of the GYE. Copyright © 2012 John Wiley & Sons, Ltd.

Fur, Fortune, and Empire: The Epic History of the Fur Trade in America

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