BEAVER DAM CAPACITY IN THE CANADIAN BOREAL PLAINS ECOZONE: AN ANALYSIS OF RIDING MOUNTAIN NATIONAL PARK
Date
2020-01-16
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0003-4856-1619
Type
Thesis
Degree Level
Masters
Abstract
Beaver, and the dams they build, have a profound impact on aquatic ecosystem-forming processes in every landscape they occupy. Beaver dams increase surface water retention, sedimentation storage, enhance riparian plant composition and have been shown to attenuate floods and augment low flows. With expected warmer future climate in Canada’s boreal region along with increasing development, understanding and monitoring beaver dam building under environmental change is critical. The purpose of this research is thus to better understand the capacity of the boreal plains ecozone of Western Canada to support beaver dams. I studied beaver dam capacity in Riding Mountain National Park, Manitoba. The Beaver Restoration Assessment Tool (BRAT) is a recently developed beaver dam building capacity model, tested thus far only along riverscapes such as in Utah. I adapted BRAT for use in RMNP and modelled results indicate the maximum beaver dam density to be ~25,000 or 9 dams/km in 2016. Manual analysis of a subset of beaver ponds using aerial images was completed to determine water storage potential. The results indicate there is substantial water storage in beaver ponds within RMNP. Beaver pond storage for 120 km2 (4%) of the park is ~5.2 million m3 of water, which is comparable to that stored in some hydroelectric dam reservoirs in Manitoba. Post-hoc analysis on the distribution of beaver dams based on physiography type indicate that the maximum beaver dam capacity in the hummocky region within RMNP is higher than modelled predictions, owing to the presence of off-channel dams. Additionally, temporal changes in beaver dam density throughout RMNP were explored by modelling the beaver dam density for 1991, 2003 and 2016. Modelled capacity was ~29,000 in 1991, which subsequently decreased to ~25,000 dams in both 2003 and 2016. The results suggest that BRAT reasonably estimates beaver dam capacity in RMNP and should be useful in informing water management plans or policies. The study also demonstrates the value of the BRAT beyond use as a reintroduction tool - as a predictive tool to determine beaver dam density within the boreal forest and changing northern habitats.
Description
Keywords
Beaver, dams, water storage, Boreal plain, modelling, climate change
Citation
Degree
Master of Science (M.Sc.)
Department
Geography and Planning
Program
Geography