Dr. Carol Johnston, formerly at the Natural Resources Research Institute in Duluth but now at South Dakota State University, recently published a book titled "Beavers: Boreal Ecosystem Engineers" summarizing the research she and her colleagues did at Voyageurs National Park on the effects of beavers on ecosystems from the 1980s to present. "This 88-year record of beaver landscape occupation and alteration documented by Johnston and colleagues from aerial photography and field work provides a unique resource toward understanding the ecosystem effects and sustainability of beaver activity."