Beavers as drivers of ecological dynamics

作为生态系统工程师，海狸通过将动态（移动）的水生系统转变为静态（静止）的水生系统，影响环境中生物和非生物成分之间的界面。生态系统工程与弹性理论有联系，弹性理论解决了非线性生态系统动力学和相对于扰动的临界点。一旦海狸在一个地区定居，重新定居和放弃事件的时间变化就提供了一个独特的机会来测试一个系统何时是最具生产力、多样性和弹性的。该研究项目考察了环境变量（如土壤、植被、水文、气候）和海狸生态（如种群动态、栖息地改变）之间的相互作用如何影响水坝的持久性和水坝失败的临界点。理论表明，扰动的中间状态更有生产力，而更有生产力的系统更稳定。虽然海狸的活动增加了生物多样性和生产力，但大坝确实会失败，导致灾难性的洪水。作为回应，我们需要量化成因景观中的关键变量，以预测水坝在相关水生系统中的持久性。此外，空间和时间变量将被确定，可以为海狸释放的风险管理提供信息。此外，还将量化水坝的主动维护、种群动态和相关环境变量对水坝持续可能性的影响。这项研究将发生在北纬高原，在骑马山国家公园（RMNP）。实地观察和自然实验将测试相对于地貌条件，殖民-放弃循环如何影响植被群落和水坝的持久性。这些数据将有助于开发可能受海狸坝破坏影响的邻近农业用地的洪水风险模型。最能预测群落放弃的因素将被应用到包含纵向数据集的预测模型中。另一个重点是评估重新占领在占用时间中的作用，以及以前被占领的生境如何产生影响重新占领和持久性的反馈循环。RMNP有长期的住宿数据，广泛的航空摄影和遥感数据。这项研究将深入了解影响水坝和生态群落持久性的变量，这些变量是由海狸的工程造成的，以及洪水的潜在影响。研究成果将帮助资源管理者平衡生物多样性和洪水风险。我们的研究结果将为在加拿大和国际上重新引入海狸进行恢复提供信息，同时减少冲突。我们将提供新的见解，方法和模型来量化生态相互作用的水文反应。该研究项目建立在一个国际研究网络的基础上，培养从本科生到博士后的高素质人才，使他们成为管理者、研究人员、领导者和创新者。

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.