Beavers as drivers of ecological dynamics

作为生态系统工程师，海狸通过将热带(移动的)水生系统改变为静止的(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，后者研究非线性生态系统动力学和与扰动相关的临界点。一旦海狸殖民了一个地区，重新殖民和遗弃事件的短暂流动就提供了独特的机会来测试一个系统何时是最多产、最多样化和最有弹性的。 该研究项目研究环境变量(例如土壤、植被、水文、气候)和海狸生态(例如种群动态、栖息地变化)之间的相互作用如何影响水坝的持久性以及水坝坍塌的临界点。理论表明，干扰的中间状态更有生产力，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，但大坝确实坍塌了，导致了灾难性的洪水。作为回应，我们需要量化成因地貌中的关键变量，以预测相关水系中大坝的持久性。此外，还将确定能够为海狸放生风险管理提供信息的空间和时间变量。此外，还将量化大坝主动维护、人口动态和相关环境变量对大坝持续生存概率的影响。 这项研究将在北部高原的骑丁山国家公园(RMNP)进行。实地观察和自然实验将测试殖民-废弃周期如何影响植被群落和大坝随着时间的推移相对于地貌条件的持久性。这些数据将有助于开发可能受到河狸大坝坍塌影响的邻近农田的洪水风险模型。最能预测殖民-放弃的因素将应用于也纳入纵向数据集的预测模型。 另一个重点是评估重新占用在占用持续时间中的作用，以及以前占用的栖息地如何产生影响重新占用和永久性的反馈循环。RMNP拥有小屋入住率的长期数据、广泛的航空摄影和遥感数据。这项研究将为影响河狸工程所导致的大坝和生态群落的持久性的变量以及洪水的潜在影响提供洞察。研究成果将帮助资源管理者平衡生物多样性和洪水风险。 我们的发现将为在加拿大和国际上重新引入海狸进行恢复提供参考，同时减少冲突。我们将提供新的见解、方法和模型来量化水文对生态相互作用的响应。这一研究计划建立在国际研究网络的基础上，培养从本科生到博士后研究员的高素质人才，并为他们成为管理者、研究者、领导者和创新者做准备。

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.