B.J. Dittbrenner, University of Washington/Beavers Northwest
This project was a continuation of a 2015 CREOi award investigating the impacts of reintroduced beavers on ecosystem resilience. Beavers are both ecosystem engineers and keystone species. As ecosystem engineers, they modify their environment through dam building to create wetland systems that reduce their predation risk and increase growth of preferred food types. Their role as keystone species results from their ability to transform a stretch of single-thread stream into a large and wide wetland complex, with numerous pools of varying depths and temperature profiles, multiple braided channels at different heights, and piles of large woody debris. The rich complexity of these systems provide habitat for an amazing abundance and number of plant, insect, fish, amphibian, mammal, and bird species. Most beavers in the US were extirpated through over-trapping by the turn of the 20th century. Only recently have we begun to see a resurgence of beaver populations and the ecological benefits they provide.
Supporting and encouraging this resurgence may become even more critical in the face of hydrologic shifts as a result of climate change. Local climate models predict that the Pacific Northwest will experience considerable hydrologic alterations over the next century. Summer precipitation and stream flow will likely decrease, as will snowpack; snow melt is projected to come earlier in the year, and winter precipitation, storm intensity, and stream temperatures will likely increase. These changes would threaten sensitive habitats and species. Both hydrologic stability and ecosystem resilience will be substantially reduced by these changes.
As ecosystem engineers, beavers have the unique capacity to not only protect existing ecological function, but also buffer against future changes and habitat destruction. Can the return of beavers into these stream systems stabilize hydrology, retain water in streams during summer months, and increase ecosystem resilience?
In 2016, CREO funds supported a full time field assistant, and the project also hosted an undergraduate student who evaluated the effectiveness of forward-looking infrared imagery (FLIR) as a tool to monitor how beavers cool stream water below dams. The project reached a milestone of 100 beavers relocated, and the final field season was completed. Final data analysis and publication are in progress, but a screening tool has already been developed to identify habitat suitable for beaver relocation as part of riparian restoration efforts.
Overall, the benefits of CREO support included significantly enhanced data-collection capabilities for the research project, continued mentoring experience for the PI, and valuable experience for the interns. Aside from the academic and applied conservation contributions of the science, CREO helped to support 12 undergraduates and recent graduates, many of whom are on a career path in ecology and conservation. Countless volunteers also gained field experience, and partnerships with landowners saved over 100 beavers through relocation instead of lethal measures. ($20,000)