Book excerpt: Like ecology, environmental science is multi- and interdisciplinary. The three major subdisciplines of environmental science are : Population, Resources, Environment. Of the above three major subdisciplines with environmental science, this book is more concerned with the third - the ecological effects of stressors, with particular reference to those associated with the activities of humans. A chapter deals with the use and abuse of biological resources and the emerging field of ecological economics. Some sections deal with environmental impact assessment; ecological monitoring; and the responsibilities of ecologists in environmental issues, environmental education, and the design of sustainable economic systems.