This book, a product of the fourth Cary Conference, amply demonstrates the achievement of a major goal of all Cary Conferences. That is, Cary Conferences were conceived to provide a forum for comprehensive discus­ sion of major ecological issues from more philosophical and comprehensive perspectives. The Institute of Ecosystem Studies is proud to make its staff and facilities available on a biennial basis for the purpose of initiating and fostering these important discussions. On the one hand, the influence of humans on ecosystems may be quite obvious, such as when a forest is cut. On the other, humans live within and among ecosystems, but ecologists largely have avoided making detailed and rigorous analyses of the more subtle effects that human activities generate. Indeed, most ecologists have sought out rather pristine or remote areas for study, rather than those which include humans. This book brings together a stimulating mix of disciplines to highlight and evaluate these problems, as well as the opportunities of including humans as integral components in studies of "natural- ecosystems. An exciting dialogue has ensued. Hopefully this book will convey some of the excitement and challenges that were generated at this Cary Conference.