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Beavers are ecosystem engineers that can dramatically change the shape of the landscape and how water moves through it. They create and maintain wetland environments across North America and Eurasia in a wide variety of places, including mountains, deserts, coasts, forests, grasslands, shrublands, etc. Despite their large influence on the landscape, there are very few programs that monitor them at the landscape, regional, or continental scale. This is partially due to how much time it takes to find and identify beaver dams in satellite and aerial images. To make it easier for us to find and understand the influence of beavers at larger scales, we built a model that can automatically find beaver dams in satellite and aerial imagery. While our model is trained to find beaver dams, this type of model has promise for finding other landscape features too. The model isn’t perfect, but it is a strong starting point and will continue to improve as more people use it.
A current challenge in ecohydrology is the incorporation of beaver dams into hydrological models. Select works have attempted to solve this problem using routing approaches, Manning coefficient variations, pond dynamics, or fully-distributed hydraulic models; however, all these approaches assume that all beaver dams are homogeneous structures and react in the same way to rainfall events. Recent findings highlight the importance of including the functional heterogeneity of beaver dams, especially the water path past the dam (dam flow state). To overcome the challenge of accounting for different dam flow states interrupting downstream water transmission in different ways, we developed BEAVERPY, a flow state-based Python package that can be coupled with the platform Cold Regions Hydrological Model (CRHM) to represent both streamflow modulation by ponds and dams, while also simulating infiltration and evapotranspiration. We used the broad-crested weir equation for the overflow dams, the Darcy equation for the seep flow dams, and the v-notch weir equation for the gapflow dams, verifying each case with synthetic experiments. To calibrate and validate the model, we instrumented the ponds and streams in a peatland fen in the Canadian Rocky Mountains in Alberta with level sensors and ‘DamCams’ (trail cameras) to capture flow type. Then, we used LIDAR DEM data and high-resolution imagery to delineate the hydrological response units. Each pond is represented as an HRU, which can interact with soil and routing modules. Finally, we conducted a scenario-testing experiment to understand the sensitivity of different beaver dam flow states for several storms. The results indicate the importance of including flow state dynamics for the beaver dam representations, and highlight the importance of integrating animal-ecological aspects into the streamflow modelling. This research has implications for understanding the use of beaver as a nature-based solution for flood mitigation and river restoration.
Hydrologic extremes dominate chemical exports from riparian zones and dictate water quality in major river systems. Yet, changes in land use and ecosystem services alongside growing climate variability are altering hydrologic extremes and their coupled impacts on riverine water quality. In the western U.S., warming temperatures and intensified aridification are increasingly paired with the expanding range of the American beaver—and their dams, which transform hydrologic and biogeochemical cycles in riparian systems. Here, we show that beaver dams overshadow climatic hydrologic extremes in their effects on water residence time and oxygen and nitrogen fluxes in the riparian subsurface. In a mountainous watershed in Colorado, U.S.A., we find that the increase in riparian hydraulic gradients imposed by a beaver dam is 10.7–13.3 times greater than seasonal hydrologic extremes. The massive hydraulic gradient increases hyporheic nitrate removal by 44.2% relative to seasonal extremes alone. A drier, hotter climate in the western U.S. will further expand the range of beavers and magnify their impacts on watershed hydrology and biogeochemistry, illustrating that ecosystem feedbacks to climate change will alter water quality in river systems.
In general, rewilding aims to reestablish vital ecological processes that can involve removing troublesome nonnative species and restoring key native species. Our rewilding call is grounded in ecological science and is necessary regardless of changing political winds. Our objective is to follow up on President Biden’s vision to conserve, connect, and restore by identifying a large reserve network in the American West suitable for rewilding two keystone species, the gray wolf (Canis lupus) and the North American beaver (Castor canadensis).
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.
A Review of Two Novel Water-Tight Beaver Dam Analogs (WTBDA) to Restore Eroded Seasonal Creeks in Drain Tile Zones to Permanent Beaver Wetlands
Reducing nutrient runoff in streams is an important task to reduce algae blooms and associated environmental damage in large waterbodies. Beaver Dam Analogs (WTBDA) are an means to address this problem. These Water Tight Beaver Dam Analogs (WTBDA) present a novel approach to this technique that also aim to restore eroded seasonal creeks to perennial wetlands.
We studied the distribution of beaver-impacted mineral wetlands and peatlands in a 7,912 km2 area of the Canadian Rocky Mountains. Using aerial photography and an existing wetland database, we inventoried 529 wetlands at elevations of 1,215 to 2,194 m; peat soils were found at 69 % of the 81 field verified wetlands.
To determine whether reintroduced beavers, as an example of native herbivorous megafauna, can increase freshwater biodiversity at the landscape scale and to compare effects on two contrasting taxonomic groups.
The research gathered in this paper discusses the beaver’s effects on: wetland carbon cycling, riparian forest structure, and biodiversity. This thesis also covers the relationship between beaver populations and the existence of wetlands, particularly the way in which beavers are an essential part of wetland ecosystems.
Potential mitigation of and adaptation to climate-driven changes in California’s highlands through increased beaver populations
Evaluating the potential for beaver to adapt to and to mitigate anticipated changes in California’s higher elevation land- and waterscapes.
Habitat engineering by beaver benefits aquatic biodiversity and ecosystem processes in agricultural streams
Dam building by beaver in degraded environments can improve physical and biological diversity
when viewed at a scale encompassing both modified and unmodified habitats.
The goal of this study was to evaluate factors such as cattle grazing that may limit the occurrence of dam-building beavers in northern New Mexico.
Ecological engineering and aquatic connectivity: a new perspective from beaver-modified wetlands, 2014
This study demonstrated that beavers actively increase the volume-to-surface area ratio of wetlands by almost 50% and that their digging of foraging channels increases average wetland perimeters by over 575%. They concluded that exclusion or removal of beavers could limit ecosystem processes and resilience.
Beaver (Castor canadensis) mitigate the effects of climate on the area of open water in boreal wetlands in western Canada, 2008
This study examined how temperature, precipitation and beaver (Castor canadensis) activity influenced the area of open water in wetlands over a 54-year period in the mixed-wood boreal region of east-central Alberta, Canada.
The U.S. Dept. of the Interior, Bureau of Land Management blog reports that in arid, high country Oregon, a series of manmade beaver dams (Beaver Dam Analogs) have created a watery oasis.
Beavers Buffering Blazes: The Potential Role of Castor canadensis in Mitigating Wildfire Impacts on Stream Ecosystems
The potential role of beavers in mitigating wildfire impacts on stream ecosystems