Bridging the fields of ecosystem science and landscape ecology, this book integrates Dr. Carol Johnston's research on beaver ecosystem alteration at Voyageurs National Park. The findings about the vegetation, soils, and chemistry of beaver impoundments synthesized in the text provide a cohesive reference useful to wetland scientists, ecosystems and landscape ecologysts, wildlife managers, and students. The beaver, Castor canadensis, is an ecosystem engineer unequaled in its capacity to alter landscapes through browsing and dam building, whose population recovery has re-established environmental conditions that probably existed for millenia prior to its near extirpation by trapping in the 1800s and 1900s. Beavers continue to regain much of their natural range throughout North America, changing stream and forest ecosystems in ways that may be lauded or vilified. Interest in beavers by ecologists remains keen as new evidence emerges about the ecological, hydrological, and biogeochemical effects of beaver browsing and construction. There is a critical need for ecologists and land managers to understand the potential magnitude, persistence, and ecosystem services of beaver landscape transformation. The 88-year record of beaver landscape occupation and alteration documented by Dr. Carol Johnston and colleagues from aerial photography and field work provides a unique resource toward understanding the ecosystem effects and sustainability of beaver activity.