A damming history: an analysis on the legacy effects of beaver dams on the composition and structure of a montane riparian ecosystem

Landscape heterogeneity is widely recognized for its positive influence on ecosystem diversity and stability. As an "ecosystem engineer," the American beaver (Castor canadensis) increases heterogeneity in riparian systems through dam-building activities, resulting in diverse wetland complexes. This study explored the impact that historic, off-channel beaver dams have on the structure and composition of the surrounding vegetative communities. Specifically, I explored how vegetative communities differed in areas of beaver occupancy history, land management impacts, and distance from the river. This study was conducted in the Kawuneeche Valley of Rocky Mountain National Park, Colorado. Field methods focused on vegetative surveys around historic, off-channel beaver dams, the Colorado River, and its major tributaries. Observed beaver sign was classified by age (historic, recent/current, absent), and statistical analysis assessed compositional differences among variables of interest. I found that historic beaver dams supported more wetland-adapted and less disturbance-tolerant plant communities. Notably, shrub cover at historic dams was similar to that of exclosed sites. In contrast, upland, disturbance-adapted species dominated areas of historic beaver activity where dams were not present. Impacts of historic agriculture are still present on the landscape, with higher intensity farming areas dominated by herbaceous species. Finally, the effects of river incision reduced shrub cover within the valley, restricting communities to the river corridor. This study demonstrated that off-channel, historic beaver ponds function as a refuge for wetland plant species in disturbed riparian systems. Incorporating these underutilized structures already present on the landscape could enhance restoration success by increasing heterogeneity and wetland health.

Name thesis:degree_name

Master of Science (M.S.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Forest and Rangeland Stewardship

Grantor dc:publisher

Colorado State University. Libraries

Year dc:date.issued

2025

Authors dc:creator

• Brunngraber, Kara, author
• Sueltenfuss, Jeremy, advisor
• Paschke, Mark, committee member
• Wohl, Ellen, committee member

• ecosystem engineer
• riparian ecosystems
• wetland restoration
• Kawuneeche Valley
• Castor canadensis
• Rocky Mountain National Park

Statement dc:rights

• Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.

Language dc:language.iso

eng, English

Identifier URI

https://doi.org/10.25675/3.02479

OAI identifier oai:identifier

oai:mountainscholar.org:10217/240925