Collaborative Research: Harnessing beaver-based restoration to conserve freshwater biodiversity across environmental gradients

About This Grant

Streams and associated riparian areas supply water for a multitude of downstream uses, reduce wildfire risk, and provide habitat for many species. Streams are increasingly threatened by drought, flood, and changing patterns of land and water use. Accordingly, billions of dollars have been spent to restore these ecosystems so that they can continue to provide vital services for people and support valuable fish and wildlife resources. Stream restoration increasingly focuses on beavers, which were once common throughout North America but were harvested nearly to extinction in the 18th and 19th centuries. Beaver-based restoration, which includes reintroducing beaver to historically occupied habitat and building structures that mimic beaver dams, has the potential for far-reaching beneficial impacts on stream and riparian ecosystems. However, it is not clear how these benefits vary across different environments and with different restoration practices. This proposal will provide critical data on how beaver-based restoration improves stream and riparian health. Such information is critical for promoting responsible use of restoration funding and effective stewardship of natural resources in a changing environment. This proposal will investigate the effects of beaver-based restoration on stream and riparian habitats and associated fish and wildlife species across divergent precipitation regimes using a large-scale, five-year field experiment and a complementary set of artificial stream experiments. Specifically, investigators will evaluate: 1) the effects of beaver reintroduction and the construction of beaver dam analogs on fish, amphibians, birds, bats, and mammals in wet vs. dry climates, 2) the specific mechanisms underlying the effects of beaver-based restoration on key habitat features under different streamflow conditions, and 3) the efficacy of different beaver-based restoration practices for achieving specific habitat and biodiversity outcomes. The field experiment will feature four types of sites: 1) beaver reintroduction (the translocation of beavers into currently unoccupied sites), 2) beaver-mimicry (the construction of beaver dam analogs), 3) unrestored controls, and 4) beaver-occupied reference sites. These site types will be replicated on the wet west side and the drier east side of the Cascades Range in the Pacific Northwest. The artificial stream experiments will provide detailed mechanistic insight into how different types of beaver-related structures, and different spatial layouts of such structures, influence stream and riparian habitat variables under varying streamflow conditions. This project is jointly funded by the Divisions of Environmental Biology and Integrative Organismal Systems through the Partnership to Advance Conservation Science and Practice Program. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.