Year of Award
2024
Document Type
Thesis
Degree Type
Master of Science (MS)
Degree Name
Systems Ecology
Department or School/College
Franke College of Forestry and Conservation
Committee Chair
Benjamin P. Colman
Committee Co-chair
Rachel L. Malison
Commitee Members
Lisa A. Eby, Diana L. Six
Keywords
Aquatic, macroinvertebrates, beaver dam analogs, restoration, foodwebs
Subject Categories
Terrestrial and Aquatic Ecology
Abstract
In response to stream degradation resulting from the near eradication of American Beavers (Castor canadensis), managers of freshwater systems have turned to using beaver dam analogs (BDAs) as one means of restoring waterways from stream and riparian degradation. Though BDAs have been shown to restore physical traits of riparian areas, their influence on macroinvertebrates and linked aquatic-terrestrial systems is not well understood. To examine how BDAs influence aquatic habitats, macroinvertebrate communities, and riparian insectivores, we compared unrestored reference stream segments to BDA-restored segments with 7-14 BDAs in three western Montana headwater streams. We collected physical stream measurements and quantitative samples of benthic macroinvertebrates using a Surber sampler, emerging adult insects using emergence traps, and macroinvertebrate infall using pan traps. We also conducted spider and bird surveys to assess if BDAs influence riparian insectivores. We found that overall, BDA-restored segments were 1.7-fold wider, 1.8-fold deeper, had 1/3rd smaller sediment sizes, and 1/6th less riffle habitat. At two sites, segments with BDA restoration supported an average of 2.6-fold higher benthic densities, comprised primarily of midges. At two reference segments, benthic densities had higher proportions of sensitive taxa (Ephemeroptera, Plecoptera, and Trichoptera). Emerging individual count flux was 5-fold higher in BDA-restored segments, primarily driven by high percentages of individuals from the midge-class. Insect infall was variable across space and time. Bird diversity and counts were not impacted by BDA-restoration while spider counts were 1.8-fold higher in BDA-restored segments. These results suggest that by modifying aquatic habitats, BDAs alter benthic community structure and therefore fluxes of food subsidies across the aquatic-terrestrial interface and can create a more robust ecosystem.
Recommended Citation
Fillion, Michelle Elyse; Colman, Benjamin P.; and Malison, Rachel L., "THE EFFECTS OF BEAVER DAM ANAOLGS ON LINKED AQUATIC-TERRESTRIAL COMMUNITIES IN WESTERN HEADWATER STREAMS" (2024). Graduate Student Theses, Dissertations, & Professional Papers. 12279.
https://scholarworks.umt.edu/etd/12279
© Copyright 2024 Michelle Elyse Fillion, Benjamin P. Colman, and Rachel L. Malison