Nutcracker sweet

A recent resurgence in temperate forest research has re-established the global significance of biomes such as boreal forest, temperate deciduous and temperate evergreen forest. This book is therefore timely in focusing on the interactions between evergreen conifers and the varied wildlife they support.

It has three main aims: to describe the fascinating natural history of stone pines and their associated animals; to provide information about the biology and ecology of bird-pine interactions, allowing the non-specialist to evaluate this symbiosis; and to draw attention to the threats that could all too easily disrupt this unique interdependent system. It achieves all these and is a compelling read.

It begins by drawing the reader into the scene, pointing out that there is furious activity going on even in the seemingly peaceful forest canopy and sketching out the major players in the relationship - the whitebark pine and Clark's Nutcracker. Ronald Lanner calls attention to the prevalence of pines in the northern hemisphere and it is pleasing that although many books written by US biologists focus exclusively on North America this does not: throughout comparative examples are used from Europe, Asia and the Pacific rim.

The first five chapters afford the reader the essential tools with which to understand and interpret the complex interactions described later on. There is a punchy discussion of the classification of pines, which alludes to the debate between taxonomic "clumpers" and "splitters" and places in context the group of pines on which the book concentrates. We also learn about stone-pine cones and seeds, how they differ from those of other pines and how they are ideally structured to attract birds.

The description of the activities of various pine-seed feeding birds culminates with what Lanner describes as the "best equipped of all corvids that feed on conifer seeds, Clark's Nutcracker". The degree of dependence between the symbionts is critically evaluated and there is a cogent discussion of the specialised mechanisms that nutcrackers require to bury and retrieve cached pine seeds. The complexity of the forest ecosystem becomes apparent as other significant organisms are introduced, including the chipmunk, the red squirrel and the grizzly bear.

Lanner tackles the issue of co-evolution between the birds and the pines, exploring the evidence for selection pressures that each could have placed on the other.

The book concludes with a warning that stone-pine populations are under threat from global climate change, insect attack and the impact of introduced diseases. The disappearance of this keystone mutualist would clearly spell trouble for the many organisms that depend on it, and in particular for Clark's Nutcracker.

Overall, Lanner paints an eloquent picture of a complex, interdependent system, bringing the forest habitat alive in a book that cannot fail to enthuse a new generation of biologists. I will certainly recommend this book to undergraduates, to colleagues and to all those who mistakenly think that conifer forests are dark, sterile environments.

Claire M. P. Ozanne is senior lecturer in life sciences, Roehampton Institute, London (University of Surrey).