Earth is a dynamic planet. As we come to appreciate its history and the long-term trends that have shaped the present, we realize that continuous change characterizes the planet, from the movement of continents to changes in the chemical composition of the atmosphere. Perhaps nowhere is change more obvious that on the planet's surface, where human land use shapes landscapes, alters ecosystems, and influences the diversity of life they support. Yet an appreciation of changing land cover and land use poses a host of questions that are difficult to answer: What types of changes are occurring now, and how fast are they occurring? How do these changes compare with those in the past, and what does it all mean for future environmental quality and the habitability of the planet?

This web site addresses some of these questions for several regions of North America. More importantly, it strives to convey the importance of a historical context for understanding ongoing changes in land cover and land use. Each section has been written by researchers for the non-specialist and reviewed independently by peer scientists. The contributors hope that the long-term perspective presented here will provide a context for assessing environmental conditions, interpreting current trends, and making more informed policy and management decisions for the future.