Influence of biomimicry structures on ecosystem function in a Rocky Mountain incised stream

Abstract

Rising levels of stream degradation have motivated a boom in restoration projects across the globe. However, postrestoration monitoring is still frequently lacking and does not always incorporate biotic responses to changes in the physical template. Beaver mimicry structures (BMSs) are becoming a popular tool to restore degraded streams throughout the American West, but relatively little is known about how these installations influence both biotic and abiotic factors, with consequences for ecosystem functioning. We monitored basal resources, organic and inorganic material standing stocks, and macroinvertebrate density, biomass, and production to quantify functional responses to BMS installation. We compared conditions at BMS sites to naturally occurring beaver dam and reference riffle sites in a low-gradient stream in southwest Montana. Thermal ranges were contracted, and daily maximum temperatures were higher, in the BMS treatment compared to the reference riffle treatment. Fine sediment standing stock and basal resources were similar in Beaver and BMS treatments, and both treatments were higher than reference riffles. All treatments differed in macroinvertebrate density, which was highest in the Beaver treatment, followed by Mimic and then Reference treatment. Biomass and secondary production were

Influence of beaver mimicry restoration on habitat availability for fishes, including Arctic grayling (Thymallus arcticus)

“…Beaver dams and beaver mimicry structures likely influence other taxa besides fish and could promote changes to food web dynamics and ecosystem processes. Previous research suggests that beaver activity increases invertebrate diversity and secondary production and can change community structure (Hood & Larson, 2014; Law et al., 2016; Reinert et al., 2022). Beaver ponds can increase habitat for amphibians but may require current occupation by beavers to achieve these documented positive effects (Dalbeck et al., 2014; Zero & Murphy, 2016).…”

“…The immediate habitat around BMS may be more relevant to less mobile species such as invertebrates and periphyton because they cannot as easily or quickly move to avoid undesirable locations. Future work might consider the number, spacing and type of structure to determine how BMS will alter lower trophic levels (Munir & Westbrook, 2021) and ultimately influence food availability for fish (Reinert et al., 2022).…”