Assessment of Rangeland Drought Mitigation Improved by Castor canadensis Impounded Water

By Marla Striped Face-Collins, ESA-SEEDS Fellow and Dr. Carol Johnston, ESA-SEEDS Mentor

Present day climate change of the prairie has resulted to some degree from the unnatural removal or extinction of a keystone species, the beaver. This animal is instrumental in facilitating the infiltration of sparse rainfall into the soil through its dam building activities. Volume of water impounded by Castor canadensis (North American beaver) was measured at the study site and compared to the nearby control site where impoundment activity by beaver is non-existent. Seven stream transects and subsequent volumetric calculations indicate that significant amounts of water are being stored in beaver ponds. Grass clippings from a plot in the study area contained almost three times the total biomass as a comparable plot in the control area, suggesting that vegetation productivity is significantly higher due to more consistently available water.  Data collected in this study to date clearly demonstrate that, by creating impoundments, beaver maintain pools of surface water in streambeds that would otherwise dry up during periods of drought. Through the process of water impoundment, beaver mitigate drought by making water available for use by livestock and other fauna that inhabit the riparian zone. Future research in this study area will address measurement of the total water budget for Oak Creek to evaluate the positive impact of beaver impounded water on the riparian zone, soil moisture, and aquifer recharge.