Much light on a tropical topic

The humid tropics contain much of the total biological diversity both in terms of species numbers and variety of different vegetation types and habitats. They are, therefore, a vast topic to cover in under 400 pages, especially since this text covers both the biological and physical aspects of the environment. This serious well-researched text will be of great value to students of the tropical environment.

It adopts a geographer's approach to the subject and is therefore most informative to a biologist such as myself. There are chapters on atmosphere, climate, soils, landscape, the hydrosphere as well as on vegetation. Each is extremely well researched, drawing on a large range of scientific references. Examples of the different topics are drawn from around the tropics rather than from a single continent. This holistic perspective comes as a welcome change. Understanding of world atmosphere and climate and its effect upon vegetation is essential in understanding the effects of climate change. The interdependence of the physical, biological and human environment is brought together well here.

The penultimate chapter deals with the environmental resources and hazards of the humid tropics. The resource section is very much about the mineral deposits rather than the biological resources. The hazards section describes such physical events as storms, floods, earthquakes, landslides and volcanic eruptions all of which tend to be more dramatic in tropical areas.

The chapter ends with a discussion of the effects of both human and natural disturbance on soil and vegetation. This includes an excellent analysis of the effects of shifting cultivation on soils and vegetation. I am glad to find that this section addresses the change in soil fauna. One of the greatest problems with tropical agriculture is that decomposer organisms which maintain soil fertility and earthworms which improve soil structure are usually neglected.

The final chapter addresses the environmental issues facing the humid tropics and focuses on deforestation and climate change. The authors take a very balanced approach and while they demonstrate the seriousness and extensiveness of tropical deforestation they present a rational scientific approach as an argument for tropical forest conservation.

Since tropical forests are so much part of the global climate system they must be conserved for their environmental function and not just because of their biodiversity. Locally deforestation has severe hydrological effects such as flooding; globally deforestation of the tropics can change climate.

The comparison made between the deforestation in Sierra Leone , Amazonian Brazil and Borneo and the Malay Peninsula shows the reasons, many of them political, for past and present deforestation. Arguments for conservation include a section on the importance of plant resources both as a source of genetic diversity and of useful products for further commercial development. The final section is a most reasonable discussion of the effects of global warming, an occurence which the authors accept as real.

The value of this book is that it treats and compares an extremely wide range of topics. Because of the extensive bibliography the specialist or the person looking for details on any one topic is unlikely to be frustrated. A list of further reading is provided for each chapter and is a good introduction to the up-to-date scientific literature about the humid tropics. This text is likely to be widely used by students of many different disciplines.

Sir Ghillean Prance is director, Royal Botanic Gardens, Kew.