The impact of invasive, introduced species on ecosystems is a critical area of research for ecology. Understanding the context-dependent responses of species and ecosystems to exotics is necessary to comprehend and predict current impacts and future alterations to vulnerable systems. The North American beaver introduction into southern Chile is a particularly compelling case because of the beaver's ability to engineer entire ecosystems. This introduction is having destructive impacts, causing dramatic changes in forests and streams. Stream food webs depend on forests for organic matter and shading. This study addresses the beaver's influences on stream invertebrate community structure, secondary production, trophic energy flow and food web dynamics in response to changes in streamside forest cover using novel techniques. It is expected that the beaver's cumulative impacts, shaping and structuring non-native communities and ecosystem function, may not be predictable based on North American studies, due to differences in vegetation and evolutionary history of beaver and forests in South America. The broader impacts of this dissertation will include cooperative research, education and conservation initiatives with local Chilean partners that will allow important parts of the research to be accomplished and also provide support and input to the local efforts.
