This revised and expanded third edition provides an introduction to the field of biogeography. It present broad-based study of the variations in the form and functioning of the biosphere at a regional and global scale. Emphasis is placed on plant biomass, the primary biological product which forms the vital food link between all organisms. The book is divided into three parts: the biosphere, ecosystems and biotic resources. Part 1. The Biosphere - presents in seven chapters, a systematic analysis of the temporal and spatial variations in the components and processes in the biosphere, dealing more fully with the biomass characteristics, primary biological productivity and biological cycling than in the previous editions. Part 2. Ecosystems in which seven chapters are devoted to a consideration of the origins, formal and functional characteristics of and human impacts on the major (forest, grassland, arid) and to distinctive island, mountain and aquatic ecosystems. Part 3. Biotic resources discusses in the final five chapters, the nature and impact of natural and human disturbance on the biosphere with respect to problems of ecosystem fragility and resilience; management and sustained yield; and the conservation of organic resources. The aim of this third edition is to produce a more systematic and structured textbook than previously which covers much the same field as before and, it is hoped, retains the original theme of the spatial variation in human - organic resource interactions. It is also hoped that it will provide under-graduate students of geography, environmental science and related disciplines with an overview of the wide ranging scope and the important inter and intra-disciplinary implications of biogeography, as well as a spring-board from which he/she may be stimulated to pursue particular aspects or problems in greater depth. As in previous editions, every effort has been made to summarize and explain those biological processes and concepts which are basic to an understanding of the complex inter-relationships within the biosphere in a way that will be palatable to and comprehensible to those readers with a limited or no formal training in the natural sciences.