Beavers are a fascinating and charismatic creature of the Northwest, but did you know they also play an important role in shaping our streams and rivers? Although beaver populations have bounced back after many populations were wiped out by hunting and habitat conversion, the century-long absence of beavers on the landscape is thought to be one of many factors contributing to the widespread degradation of streams in the western US. As climate change exacerbates drought, which in turn places additional stress on streams, there has been increasing focus on beaver-related restoration as a climate adaptation strategy and approach for restoring degraded streams. A recent NW CASC study offers a framework for evaluating the efficacy of beaver-related restoration and similar efforts.
Nature restoring nature – beavers as an adaptation strategy
Beaver-related restoration (BRR) involves bringing beaver dams back to landscapes by transferring beavers to degraded streams, building artificial dams, and restoring vegetation along streams to provide dam-building material that attracts beavers.
BRR is a process-based restoration strategy, meaning that it aims to restore processes, like dams storing water and sediment, thought to be vital to sustaining freshwater ecosystems. The same thing that makes BRR exciting — the concept of restoring nature with nature — also makes it complex, since restoration outcomes depend on complicated processes and factors, like beaver ecology and adjacent land uses, over which humans have limited control. This complexity can make this type of restoration difficult to evaluate.
On the one hand, process-based restoration methods like BRR are often inexpensive and low-tech, holding potential to be more scalable than more expensive and technical restoration methods. On the other hand, very few BRR projects have been carefully monitored, making it hard to discern whether the outcomes could be replicated in other locations.
Responding to the lack of robust evaluation of BRR projects, a recent NW CASC study offers a new framework for evaluating beaver-related restoration and other process-based restoration strategies. This framework moves away from a success-failure paradigm towards a more adaptive evaluation approach that can help researchers set more realistic expectations for project outcomes. Instead of setting rigid goals at the beginning of a project and evaluating effectiveness at the end, this study details a framework that can be used to document what happens throughout a project, where outcomes diverge from initial expectations and whether the goals for the project shift. Using this framework to document restoration projects through collecting both qualitative and quantitative data can help inform actions during the project as well as identify patterns that can inform future research and restoration efforts.