A Magic Web

  • Egbert Giles Leigh &
  • Christian Ziegler
Oxford University Press: 2003. 292 pp. $40
Forest food: a broad-billed motmot arrives home bearing an unfortunate beetle for its chicks' dinner. Credit: C. ZIEGLER/SMITHSONIAN TROPICAL RES. INST.

Tropical rainforests are the settings for innumerable interactions between millions of organisms, a centrepiece of evolution. A Magic Web showcases the complexity of these interactions, using the rainforest that has been studied more than any other in the world, that of Barro Colorado Island (BCI), a 15-km2 island in the Panama Canal.

Its author, Egbert Leigh, has worked on BCI since the 1960s, and is especially concerned about what creates and supports tropical diversity. Here he summarizes data collected by hundreds of investigators, and argues that the finely tuned web of interactions between organisms is an important basis for the species diversity and complexity of tropical rainforest. Leigh points to many differences among species that are driven by direct competition. He argues convincingly for an equal importance of interactions between animals and plants. Plants diversify in their ways of escaping herbivores and enticing animals to pollinate their flowers and disperse their seeds. Animals diversify in the way they subsist on plants and avoid being eaten by other animals. It is a dynamic web; changes in climate can alter plant processes, with knock-on effects on the food available to animals. Loss of species, often induced by humans, unravels the web.

Leigh's wide-ranging vision truly comes alive when it meshes with Christian Ziegler's striking images. Ziegler has a degree in tropical biology and spent 15 months on the island photographing for this book. His collection of the typical as well as exceptional sights of BCI reveals a great intimacy with the forest. Ziegler does not simply illustrate the science, but rather illuminates each topic discussed, leading to a strong sense of the interactions everywhere in the jungle. Highlights include the sections on forest light gaps and plant diversity, on ant colonies, and on animal mimicry and camouflage.

The book will appeal to a broad audience. As a coffee-table book, it is enjoyable for its photographs and captions alone. The main text provides a useful introduction to tropical rainforest, surveying a wide range of ecological concepts — although, of necessity, briefly and in simple terms. These concepts are grounded with entertaining metaphors from human society. There are numerous comparisons with other ecosystems, and 'back of envelope' calculations. Ultimately, the book will enrich any scientist's view of biology. The tropical biologist will crave returning to the field.

Of course, even such a detailed treatment can be only a rough sketch of the intricate network of tropical-rainforest life. Leigh jokes that humans are not distinguished for their omniscience, and Ziegler reminds us how elusive are the visions of nature that he depicts. To fathom the web in all its detail, we will need to step up collaborations between scientists with diverse expertise and approaches. BCI, with its terrific facilities, has helped to build many bridges. Leigh and Ziegler's colourful synthesis should inspire many more to the task.