Dr. Rebecca Brown
Climate change and fire suppression have altered historic fire regimes creating conditions for larger, high severity fires. Intense burns denude vegetation, alter hydrology, and cause channel incision, impairing riparian function. Burn severity varies based on topography and increases with distance from water sources like lakes, streams, and wetlands. Beaver introduction is a passive technique to restore incised and degraded streams using their unique abilities to build dams, store water and create wetland environments. The objective of this study was to assess whether beaver impoundments increase landscape resistance to wildfire by increasing riparian soil and vegetation moisture levels. We hypothesize that riparian areas impounded by beaver will have increased soil and fuel moisture throughout the fire season compared to riparian zones without beaver. To assess potential ignition and fire behavior, we collected soil and fuel moisture samples throughout the fire season, above, within and below 10 beaver impounded streams and 10 non-impounded reference reaches within the Methow Watershed, WA, USA. Soil moisture differences among transects and beaver/non-impounded sites were compared using a repeated measures analysis. We found beaver impounded sites had higher average soil and dead fuel moisture than non-impounded sites. Unexpectedly, beaver dam presence was not associated with increased live fuel moisture content. These results suggest that beaver impounded riparia may have a higher capacity to withstand low to moderate burn events compared to non-impounded riparian zones. Beaver restoration could provide land managers with a low-cost method to increase riparian burn resistance on a watershed scale.
Weirich, Joseph and Brown, Rebecca PhD., "Beaver Moderated Fire Resistance in the North Cascades, WA, USA" (2020). 2020 Symposium Posters. 65.