Maintaining Biodiversity in Forest Ecosystems


  • Richard Ferris

M.L. Hunter Jr. (1999)

Pp. xiv + 698. Cambridge University Press.

?27·95 (paperback), ISBN 0-521-63768-6;

?65·00 (hardback), ISBN 0-521-63104-1.

Foresters are facing multiple challenges to the way they practice their art. This book should be part of their library, drawing together a wide range of expertise into one accessible volume. The concentration upon forests managed for timber production is a particular strength, as this helps to provide a balanced view of the problems and solutions, recognizing the important role that managed forests can have in conserving biodiversity.

The key to success is the recognition that management should be at two scales: a macro approach, managing forest landscapes; and a micro approach, managing forest stands. These are addressed in two major sections of the book, preceded by an outline of biodiversity and ecological forestry – what it is and why it is important – and followed by a useful section on synthesis and implementation. Hunter does not see biodiversity as an option, but rather as a central element in this new forestry. The emphasis is upon understanding and maintaining the integrity of natural patterns and processes, working in harmony with them even when it is financially difficult or inconvenient to do so. In order to achieve this, it is argued that recognized silvicultural systems have been too restrictive, and that foresters should not be concerned with pigeon-holing a particular practice. This outlook is both refreshing and liberating, and the book succeeds in formulating a working hypothesis for maintaining biodiversity without being overly prescriptive.

At the macro scale, the importance of species composition, forest mosaics and the factors which shape them, the role of edges, and the process of fragmentation are all examined. Maintenance of species mixtures in patterns which more closely reflect unmanaged ecosystems has long been proposed, the great challenge being to determine the appropriate composition of stands in the landscape. It is acknowledged that to achieve this requires large areas where natural disturbances can occur with sufficient intensity, frequency and extent; few such areas remain on this planet! Furthermore, the inadequacy of equilibrium models to explain vegetation change has demanded that tools be developed to assign probabilities to successional pathways, allowing modelling to be used to project potential outcomes of different management options. The review of abiotic factors influencing disturbance patterns highlights the true extent of landscape patchiness, with important implications for biodiversity conservation strategies. The value and characteristics of forest edges are emphasized, and it is clear that they cannot be regarded as static measures of forest communities, having considerable impact upon exchanges of energy, nutrients and organisms. Fragmentation is examined, with emphasis placed upon the organism-centred view, rather than what we perceive; and a series of pertinent challenges for managers is set out. Special attention is given to riparian forests and forested wetlands, both disproportionate contributors to biodiversity in some regions.

The management of forest stands covers the now familiar issues of dying and dead wood, outlining the importance of the resource but also providing practical advice on how to set targets, estimate availability and recruitment, and manage this to meet the needs of wildlife. The particular relationship between vertical structure and biodiversity receives deserved attention. There then follow a series of reviews on the impact of plantation forestry on biodiversity, special species, and genetic diversity. Although forestry is encouraged to take an increasingly holistic approach, species-orientated management is still a necessity for a number of reasons. The two approaches are seen as complementary, focusing efforts at multiple scales, a recurring theme of the book. While single-species management often has a high profile, genetic diversity ‘rarely makes headline news’. A number of approaches to the conservation of forest gene pools, and proposals for integration of genetic management with other conservation efforts, are outlined.

The synthesis of information in this book calls for the restoration of natural processes and species, while allowing for a flow of forest products. At the same time, networks of forest reserves are advocated, recognizing their particular importance in forests managed for timber, but acknowledging that they are insufficient alone for effective conservation. Aspects of reserve design, implementation and management are examined. Forest organization, management and policy are considered, using a systems approach at a hierarchy of levels. Finally, the economic and social perspectives are examined, highlighting the difficulties in establishing non-market amenity values of forest reserves and the monetary benefits of biodiversity. The need to build a consensus view is central to the success of forest management planning, and this would seem to be the underlying purpose of this book – to present a balanced argument for managed forests, where timber production and maintenance of biodiversity can be achieved through a series of pragmatic decisions.

Although it has a predominantly North American slant, the extensive literature upon which the book draws and the general principles covered make it an invaluable text for students and forestry professionals alike. This book will take its place alongside Perry (1994), Peterken (1996), Kohm & Franklin (1997), not to mention the earlier book by Malcolm Hunter (1990), as a useful addition to this subject. It is lively and challenging, full of ideas that set one thinking about preconceptions of forestry, advancing our thinking about ecosystem management, and opening up a number of exciting future scenarios.