This collection of papers is concerned with the ecology and occupation of mountain areas. Focusing especially on ecological problems in these areas, its theme is an outgrowth of "Man and the Biosphere," a fledgling international program sponsored by UNESCO. The book is particularly concerned with section 6 of the UNESCO program, "Impact of Human Activities on Temperate and Tropical Mountain and Tundra Ecosystems." Each of the contributing authors is an internationally recognized authority, and each has provided a review of the state of knowledge and a discussion of special problems and areas for future research in his or her field of specialization.