A Study of Beaver Pond Morphology and Site Characteristics After Disturbance in Eastern Glacier National Park, Montana
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Little research has been conducted on alterations or disturbances to beaver ponds, which is important to understanding beavers’ interactions with the environment. Three sites with beaver-pond sequences in Glacier National Park in northwest Montana were chosen for study, including sites near Saint Mary Lake, Lake Sherburne, and Lower Two Medicine Lake. The Saint Mary Lake site was subjected to an extensive forest fire in the watershed in 2006. The latter two sites are adjacent to human-constructed reservoirs. Aerial photos were used to create maps in a Geography Information System for all three site locations over a twenty year span from 1991-2011. Statistical analysis compared average pond areas of beaver-pond sequences between sites, as well as a comparison of average area of pond sequences between years and site locations. Analysis proved that the Lower Two Medicine is statistically different in average area of pond sequences when compared to the other sites, but no statistical difference in beaver-pond area existed between the Saint Mary and Lake Sherburne sites. There was also no statistical difference between area of ponds when compared to different years. Varying lake levels because of irrigation draw-down at Lake Sherburne and Lower Two Medicine created a dynamic base level, whereas the local base level for the Saint Mary ponds remains relatively constant year round. The fluctuating base levels of Lower Two Medicine and Lake Sherburne ensure dynamic environments for the creek systems, and the ponds along it. The Saint Mary Ponds appear to be undergoing rapid siltation following the 2006 forest fire within the drainage basin.