Presentation Type
Oral Presentation
Category
STEM (science, technology, engineering, mathematics)
Abstract/Artist Statement
Starting in the 17th century, beavers were nearly eradicated from their historic range. Though today their populations are improving, the lack of beaver dams in aquatic systems has left a lasting impact on the environment. As a result, managers of freshwater systems have turned to beaver dam analogs (BDAs) as one technique for stream restoration. BDAs are human constructed structures designed to mimic natural beaver dams and their geomorphic, hydrologic, and ecological effects. Though BDAs have proven to be a useful restoration technique, there has been little research on how they influence macroinvertebrate communities, which serve as a vital food source for fish and to adjacent riparian insectivores such as spiders and birds. My research aims to understand how BDAs influence macroinvertebrate and riparian insectivore communities in three intermountain headwater streams in western Montana by comparing unrestored reference stream segments to BDA-treated segments consisting of complexes of 7-14 BDAs. To understand the ecosystem-level effects of BDAs at these sites, I have collected macroinvertebrates from within the streams (benthic samples), macroinvertebrates leaving the streams (emergence traps) and those falling into the streams (pan traps) along with variables that describe the physical environment. I also conducted spider and bird surveys to assess how BDA influence riparian insectivores which rely on emerging insects for food. I will use these samples to quantify community metrics and compare BDA-treated segments to reference segments using non-metric multidimensional scaling and generalized linear mixed-effects models. Using these methods, BDA-treated segments are shown to have more tolerant taxa usually found in pools compared to reference segments. My research will help scientists and managers understand the impacts of BDAs on linked stream-riparian communities so best practices can be followed as they are considered for stream restoration throughout the western landscape.
Mentor Name
Benjamin Colman
Personal Statement
When walking onto a landscape enriched with beaver dams, one notices the complexity and vibrancy they offer to aquatic and riparian ecosystems. Valley bottoms laced with meandering streams and cool pools create a sanctuary for trout, Wilson’s Warblers, and the occasional black bear. Large emergences of gnats and mayflies from the pooled water feed this myriad of diversity, linking the aquatic system to the nearby riparian forest. Headwater streams like this and their adjacent riparian corridors are some of the most important and fragile ecosystems we have in the western US. Their proximity to riparian ecosystems allows for an intimate relationship between aquatic and terrestrial communities creating high biodiversity, supplying downstream rivers with carbon and nutrients, and determining downstream conditions. Insects are a key part of the importance of headwater streams because they are a vital food source for many aquatic and riparian insectivores, and they break down leaves from the riparian ecosystem which flow downstream as nutrients. Unfortunately, headwater streams are threatened due to the loss of beaver dams on the landscape and the geomorphic, hydrologic, and ecological effects the dams provide. BDAs are one way to restore headwaters, but little is known about how they affect vital insect communities and the roles they play in linked aquatic-terrestrial ecosystems. My research aims to understand how insects, and the communities they are linked to, are affected by BDAs in the Lolo and Blackfoot drainages of western Montana by comparing both aquatic and terrestrial insects and riparian insectivores such as birds and spiders in unrestored upstream segments to downstream BDA-treated segments. With BDAs becoming common in much of the west, research at the ecosystem level is necessary to fully understand if implementing BDAs is a successful technique to restore and protect our valuable headwater systems.
Beaver Dam Analogs Change Macroinvertebrate Communities in Headwater Streams, Western Montana
UC 327
Starting in the 17th century, beavers were nearly eradicated from their historic range. Though today their populations are improving, the lack of beaver dams in aquatic systems has left a lasting impact on the environment. As a result, managers of freshwater systems have turned to beaver dam analogs (BDAs) as one technique for stream restoration. BDAs are human constructed structures designed to mimic natural beaver dams and their geomorphic, hydrologic, and ecological effects. Though BDAs have proven to be a useful restoration technique, there has been little research on how they influence macroinvertebrate communities, which serve as a vital food source for fish and to adjacent riparian insectivores such as spiders and birds. My research aims to understand how BDAs influence macroinvertebrate and riparian insectivore communities in three intermountain headwater streams in western Montana by comparing unrestored reference stream segments to BDA-treated segments consisting of complexes of 7-14 BDAs. To understand the ecosystem-level effects of BDAs at these sites, I have collected macroinvertebrates from within the streams (benthic samples), macroinvertebrates leaving the streams (emergence traps) and those falling into the streams (pan traps) along with variables that describe the physical environment. I also conducted spider and bird surveys to assess how BDA influence riparian insectivores which rely on emerging insects for food. I will use these samples to quantify community metrics and compare BDA-treated segments to reference segments using non-metric multidimensional scaling and generalized linear mixed-effects models. Using these methods, BDA-treated segments are shown to have more tolerant taxa usually found in pools compared to reference segments. My research will help scientists and managers understand the impacts of BDAs on linked stream-riparian communities so best practices can be followed as they are considered for stream restoration throughout the western landscape.