The Great Plains is a large and very important grassland ecosystem covering roughly one-fourth of the United States. Human activity has had an impact on this environment for thousands of years, especially since the 1800s, when hunters killed off almost all of the enormous herds of American bison that once roamed the area. Readers will learn how agricultural practices, global warming, hunting, and urban development have changed the area. They'll also learn about conservation efforts to both restore the Great Plains and prevent further damage. Informative fact boxes, sidebars, and full-color photographs provide extra in-depth information on the changing environment of the Great Plains.