The Environmental Monitoring and Assessment Program was created by EPA to develop the capability for tracking the changing conditions of our natural resources and to give environmental policy the advantages ofa sound scientific understanding of trends. Former EPA Administrators recognized early that contemporary monitoring programs could not even quantify simple unknowns like the number of lakes suffering from acid rain, let along determine if national control policies were benefiting these lakes. Today, adding to acidification impacts are truly complex problems such as determining the effects of climate change, of increases in ultraviolet light, toxic chemicals, eutrophication and critical habitat loss. Also today, the Government Performance and Results Act seeks to have agencies develop performance standards based on results rather than simply on levels of programmatic activities. The charge to EMAP of ecosystems is, therefore, the same today as it was a with respect to measuring the condition decade ago. We welcome the increasing urgency for sound scientific monitoring methods and data by efforts to protect and improve the environment. Systematic nationwide monitoring of natural resources is more than anyone program can accomplish, however. In an era of declining budgets, it is crucial that monitoring programs at all levels of government coordinate and share environmental data. EMAP resources are dwarfed by the more than $500 million spent on federal monitoring activities each year.

The monitoring of point sources by the Environmental Protection Agency (EPA), the states, and the tribes has documented and helped reduce the levels of chemical stressors affecting our ecosystems. With the controls on point sources reducing chemical contamination, new environmental challenges associated with nonpoint sources have emerged. To adequately deal with these new problems, EPA's Office of Research and Development recognized the need to develop an overall under standing of the condition of our ecological resources, the trends in their condition, and the stressors affecting these systems on a broad scale. Toward this end, the En vironmental Monitoring and Assessment Program (EMAP) was established by EPA and has been strategically developing the scientific tools and techniques to monitor and assess the status and trends of aquatic ecosystems. EMAP scientists have developed new indicators and probability-based de signs to fill data gaps in the development of regional-scale assessments of our aquatic resources, as required in the Clean Water Act. We have a scientifically de fensible approach that allows: 100 percent coverage of the aquatic resources within broad geographic areas and the formulation of reference 'conditions for es tablishing the health of these resources. The use of these indicators and designs were successfully demonstrated in the landscapes, streams, and estuaries of the mid-Atlantic states as part of the Mid-Atlantic Integrated Assessment (MAlA).

Different monitoring initiatives have been undertaken in Canada and the United States since the 1980s at national and regional scales. In the United States, starting in 1990, partners from federal and state agencies established the Forest Health Monitoring (FHM) program with the goal of monitoring and evaluating the status, conditions, and trends in indicators of forest health. The FHM program has evolved into a system where FHM plots are integrated with the national Forest Inventory and Analysis program. In Canada, early attempts can be traced back to the 1980s with the Acid Rain Early Warning System. After its ending, Canadian forest monitoring was mostly carried out within the redesigned National Forest Inventory, Ecological Monitoring and Assessment Network, and regional initiatives. One of them, implemented in the Athabasca Oil Sands Region of Alberta since 1997, is presented here.

Often a commitment to large ecosystem initiatives is linked both conceptually and legally with requirements for ecological monitoring as a means of evaluating the effectiveness of management actions. Programs to determine ecosystem status and trends can contribute significantly to the resolution of difficult and contentious management questions, and can playa key role both in sharpening the focus of research questions and in developing adaptive approaches to resource management. Monitoring Ecosystems brings together leading scientists and researchers to offer a groundbreaking synthesis of lessons learned about ecological monitoring in major ecoregional initiatives around the United States. Contributors-Donald L. DeAngelis, Lance H. Gunderson, Barry R. Noon, John C. Ogden, Craig J. Palmer, Keith M. Reynolds, Paul L. Ringold, John R. Sauer, Lawrence E. Stevens, and many others-present insights and experiences gained from their work in designing, developing, and implementing comprehensive ecosystem monitoring programs in the Pacific Northwest, the lower Colorado River Basin, and the Florida Everglades. The book: outlines the conceptual and scientific underpinnings for regional-scale ecosystem monitoring, examines the role and importance of data management, modeling, and integrative analyses, considers techniques for and experience with monitoring habitats, populations, and communities Chapters by the editors synthesize and expand on points made throughout the volume and present recommendations for establishing frameworks for monitoring across scales, from local to international. Monitoring Ecosystems presents a critical examination of the lessons learned from direct experience along with generalized conclusions that canbe applied to monitoring programs in the United States and around the world. It is a vital contribution to science-based monitoring efforts thatwill allow those responsible for developing and implementing ecoregional initiatives to make use of knowledge gained in previous efforts, enabling them to focus their energies on system-specific questions and problems.