Thorough, detailed, and scientifically up-to-date, Prairies: A Natural History provides a comprehensive nontechnical guide to the biology and ecology of the prairies, or the Great Plains grasslands of North America, offering a view of the past, a vision for the future, and a clear focus on the present. With a total area of more than 3.5 million square kilometers (500,000 in Canada and the remainder in the United States), the prairies occupy the heartland of the continent, a vast, windswept plain that flows from Alberta south to Texas and from the Rockies east to the Mississippi River. This is big sky country-the largest ecosystem in North America and, until recently, one of the richest and most magnificent natural grasslands in the world. Today, however, the North American prairies are among the most altered environments on Earth.