Re-centering relations: The trouble with quick fix approaches to beaver-based restoration (original) (raw)
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Saving the Dammed: Why We Need Beaver-Modified Ecosystems. By Ellen E. Wohl
Mountain Research and Development, 2020
Saving the Dammed is Ellen Wohl’s homage to beavers, describing their unique engineering prowess, the wider environmental impacts they exert, and why we should care. Throughout the book, Wohl binds a lifetime of professional riverine experience, observations of her local beaver population, gray literature, and primary literature to convey the benefits of beavers and convince the reader why we need more beaver-modified ecosystems. At first glance, the book title is a strong statement (and having a pun as a title will likely split the opinion of readers; personally, I think the title is fantastic)—though it suggests that humans have a role in saving beavers, which is ironic given our previous role of hunting them to the edge of extinction. Beavers (Castor fiber and Castor canadensis) were once widespread in their native range across Europe and North America, respectively, but their numbers were severely reduced because of hunting and habitat loss. Recently, populations have been reint...
Survey of Beaver-related Restoration Practices in Rangeland Streams of the Western USA
Environmental Management, 2017
Poor condition of many streams and concerns about future droughts in the arid and semi-arid western USA have motivated novel restoration strategies aimed at accelerating recovery and increasing water resources. Translocation of beavers into formerly occupied habitats, restoration activities encouraging beaver recolonization, and instream structures mimicking the effects of beaver dams are restoration alternatives that have recently gained popularity because of their potential socioeconomic and ecological benefits. However, beaver dams and dam-like structures also harbor a history of social conflict. Hence, we identified a need to assess the use of beaver-related restoration projects in western rangelands to increase awareness and accountability, and identify gaps in scientific knowledge. We inventoried 97 projects implemented by 32 organizations, most in the last 10 years. We found that beaver-related stream restoration projects undertaken mostly involved the relocation of nuisance beavers. The most common goal was to store water, either with beaver dams or artificial structures. Beavers were often moved without regard to genetics, disease, or potential conflicts with nearby landowners. Few projects included postimplementation monitoring or planned for longer term issues, such as what happens when beavers abandon a site or when beaver dams or structures breach. Human dimensions were rarely considered and water rights and other issues were mostly unresolved or addressed through ad-hoc agreements. We conclude that the practice and implementation of beaver-related restoration has outpaced research on its efficacy and best practices. Further scientific research is necessary, especially research that informs the establishment of clear guidelines for best practices.
The Return of Beavers to Southern Piedmont Streams: Stream Restoration or Disruption?
2003
The return of beaver to streams in Guilford County, North Carolina has encountered widely different responses in rural and urban landscape contexts. We found that beaver were viewed as positive agents of stream restoration in a project intended to rank potential riparian conservation easements in rural Guilford County. The response to beaver in two urban neighborhoods was to demand their eradication as a public nuisance. A primary goal of stream restoration in environmental planning is the recreation of natural conditions in streams altered by human action. Successful implementation of that goal will require clear definitions of what constitutes natural form and function, and human accommodations to the changes reintroduced species may bring to local environments.
2019
Across the western United States, researchers are increasingly working with beaver (Castor canadensis) for process-based stream and watershed restoration. One recently-developed geographic information system-based tool, the Beaver Restoration Assessment Tool (BRAT), analyzes opportunities for beaverassisted restoration (BAR) at a landscape-scale. However, this tool benefits significantly from human dimensions-inclusive, basin-centralized beaver knowledge for proper interpretation. Unfortunately, this information is scattered or absent in most semi-arid and arid southern California basins. This study thus sought to gather and produce this information through an explorative, benefits-maximizing approach to landscape-scale BAR opportunities assessment in one of these basins, the Salinas River. 49.2 km of beaver dam field surveys, an emailed survey and interviews completed by 39 riparian organizations and residents, and a BRAT model run produced: an ANOVA-driven statistical determinatio...
Alteration of North American Streams by Beaver
BioScience, 1988
B eaver (Castor canadensis) provide a striking example of how animals influence ecosystem structure and dynamics in a hierarchical fashion. Initially beaver modify stream morphology and hydrology by cutting wood and building dams. These activities retain sediment and organic matter in the channel, create and maintain wetlands, modify nutrient cycling and decomposition dynamics, modify the structure and dynamics of the riparian zone, influence the character of water and materials transported downstream, and ultimately influence plant and animal community composition and diversity (Naiman and Melillo 1984, Naiman et al. 1986). In addition to their importance at the ecosystem level, these effects have a significant impact on the landscape and must be interpreted over broad spatial and temporal scales as beaver population dynamics shift in response to disturbance, food supply, disease, and predation. Although once more prevalent than they are today, beaver-induced alterations to drainage networks are not localized or unusual. Where beaver remain largely free of management or trapping, their activities may influ
Beaver: Nature's ecosystem engineers
WIREs Water, 2020
Beavers have the ability to modify ecosystems profoundly to meet their ecological needs, with significant associated hydrological, geomorphological, ecological, and societal impacts. To bring together understanding of the role that beavers may play in the management of water resources, freshwater, and terrestrial ecosystems, this article reviews the state‐of‐the‐art scientific understanding of the beaver as the quintessential ecosystem engineer. This review has a European focus but examines key research considering both Castor fiber—the Eurasian beaver and Castor canadensis—its North American counterpart. In recent decades species reintroductions across Europe, concurrent with natural expansion of refugia populations has led to the return of C. fiber to much of its European range with recent reviews estimating that the C. fiber population in Europe numbers over 1.5 million individuals. As such, there is an increasing need for understanding of the impacts of beaver in intensively pop...
BioScience, 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.
Using ecosystem engineers as tools in habitat restoration and rewilding: beaver and wetlands
Potential for habitat restoration is increasingly used as an argument for reintroducing ecosystem engineers. Beaver have well known effects on hydromorphology through dam construction, but their scope to restore wetland biodiversity in areas degraded by agriculture is largely inferred. Our study presents the first formal monitoring of a planned beaver-assisted restoration, focussing on changes in vegetation over 12 years within an agriculturally-degraded fen following beaver release, based on repeated sampling of fixed plots. Effects are compared to ungrazed exclosures which allowed the wider influence of waterlogging to be separated from disturbance through tree felling and herbivory. After 12 years of beaver presence mean plant species richness had increased on average by 46% per plot, whilst the cumulative number of species recorded increased on average by 148%. Heterogeneity, measured by dissimilarity of plot composition, increased on average by 71%. Plants associated with high moisture and light conditions increased significantly in coverage, whereas species indicative of high nitrogen decreased. Areas exposed to both grazing and waterlogging generally showed the most pronounced change in composition, with effects of grazing seemingly additive, but secondary, to those of waterlogging. Our study illustrates that a well-known ecosystem engineer, the beaver, can with time transform agricultural land into a comparatively species-rich and heterogeneous wetland environment, thus meeting common restoration objectives. This offers a passive but innovative solution to the problems of wetland habitat loss that complements the value of beavers for water or sediment storage and flow attenuation. The role of larger herbivores has been significantly overlooked in our understanding of freshwater ecosystem function; the use of such species may yet emerge as the missing ingredient in successful restoration.
Beavers and biodiversity: the ethics of ecological restoration
This paper is about the value conflicts that lie behind ecological restoration initiatives. We focus on a case of beaver reintroduction in southern Scandinavia. We ask: what assumptions 5 about the value of nature and biodiversity underpin nature restoration, and in particular species restoration? Beavers have been reintroduced not only to ensure their long-term survival as a species, but as agents that foster biodiversity and promote variation in the natural environment. In the paper, we show that appeals to biodiversity are made by both advocates and opponents of species restoration, but with very different results. We suggest that this is 10 because two quite different conceptions of biodiversity are at stake. On one conception, biodiversity is constituted by certain "end-states". On the other, it is defined by a certain kind of "historical" process.