This report is a comprehensive summary of the status and trends of our nation’s biological resources. The report describes the major processes and factors affecting biological resources, and it treats regional status and trends. Authors of the chapters and boxes in this two-volume report were drawn from federal and state agencies, universities, and private organizations, reflecting the U.S. Geological Survey’s national partnership approach to providing comprehensive, reliable information about our biological resources. Following scientific tradition, each chapter and box was peer-reviewed by anonymous scientific reviewers.