Beavers as drivers of ecological dynamics

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As ecosystem engineers, beavers influence the interface between biotic and abiotic components of the environment, by changing lotic (moving) aquatic systems into lentic (still) ones. Ecosystem engineering has linkages to resilience theory, which addresses nonlinear ecosystem dynamics and tipping points relative to perturbations. Once beavers colonize an area, a temporal flux of recolonization and abandonment events presents unique opportunities to test when a system is most productive, diverse and resilient. This research program examines how the interplay between environmental variables (e.g. soils, vegetation, hydrology, climate) and beaver ecology (e.g. population dynamics, habitat alterations) affects persistence of dams and tipping points where dams fail. Theory suggests that intermediate states of disturbance are more productive, and more productive systems are more stable. While beaver activities increase biodiversity and productivity, dams do fail, leading to catastrophic flooding. In response, we need to quantify key variables in castrogenic landscapes to predict persistence of dams in associated aquatic systems. In addition, spatial and temporal variables will be identified that can inform risk management for beaver release. Moreover, the influence of active maintenance of dams, population dynamics, and related environmental variables on the probability of dam persistence will be quantified. This research will occur in a boreal highland plateau, at Riding Mountain National Park (RMNP). Field observations and natural experiments will test how colonization-abandonment cycles impact vegetation communities and persistence of dams over time relative to geomorphologic conditions. These data will aid development of flood-risk models for adjacent agricultural lands potentially affected by failure of beaver dams. Factors that best predict colonization-abandonment will be applied to predictive models that also incorporate longitudinal data sets. Another focus is the assessment of the role of reoccupation in occupancy duration and how previously occupied habitats create feedback loops affecting reoccupation and permanence. RMNP has long-term data for lodge occupancy, extensive aerial photography and remote sensing data. This research will provide insights into variables that influence persistence of dams and ecological communities resulting from engineering by beavers, and potential impacts of floods. Research outputs will aid resource managers in balancing biodiversity and flood risk. Our findings will inform reintroductions of beavers for restoration in Canada and internationally while reducing conflicts. We will provide new insights, methods and models to quantify hydrological responses to ecological interactions.This research program builds on an international research network to train highly-qualified personnel from undergraduate students to postdoctoral fellows, and prepare them to become managers, researchers, leaders and innovators.