J. Cracraft & F.T. Grifo (eds) (1999) The Living Planet in Crisis: Biodiversity Science and Policy. Pp. xxiv + 311. Columbia University Press, New York. ISBN 0-231-10865-6. Price £19.95 (paperback).

This collection of papers, as its subtitle implies, contains scientific reports on the current state of biodiversity and its rates of loss, as well as accounts concerning the implications of these losses for our species, and the policies needed for the reduction of extinction rates. The debate about how many species there are on earth is taken up by Nigel Stork, who argues that the currently proposed figure of about 13 million species could easily be doubled or halved depending on the accuracy of estimates of tropical diversity. Biodiversity in freshwaters, the recent (past 500 years) history of mammalian extinction, current global patterns of extinction and the economic and social consequences of such patterns, are all analysed in this collection of essays.

B.R. Allanson & D. Baird (eds) (1999) Estuaries of South Africa. Pp. + 340. Cambridge University Press, Cambridge, UK. ISBN 0-521-58410-8. Price £85 (hardback).

The very extensive literature that has been published and the intensive work that has been conducted on South African estuarine ecology have been brought together here in a single edited volume. Introductory chapters concern the geomorphology, sedimentology, hydrodynamics and chemistry of the estuaries, followed by an account of their primary production. This production section is divided into two, dealing first with microalgae, then with macrophytes, including both macroalgae and salt marsh vegetation. Nitrate eutrophication is a problem in the South African estuaries, with Eichornia crassipes becoming important in the regions with lower salinity. Mangroves are found in regions where the mean air temperature does not fall below 19 °C and they are given a chapter of their own. Zooplankton, invertebrates, fish and birds, each occupy separate chapters and the book closes with overviews of the estuarine ecosystem and its interaction with humans, both by exploitation and by conservation management. A well edited, information packed book.

A. Moen (1999) National Atlas of Norway: Vegetation. Pp. 200. Norwegian Mapping Authority, Hønefoss. ISBN 82-7945-000-9. Price £40 (hardback).

Norway, despite being a relatively small country, spans three major biomes, from deciduous oak forest in the south, through boreal coniferous forest to the open birch tundra of the far north. This splendidly produced atlas begins with topography, climate and soils, followed by an illustrated account of Norway's vegetation history and biogeography, with examples of various plant distribution patterns and biogeographical affinities. The vegetation types of Norway are outlined very briefly and their distributions in relation to the climate zones are described. The northward drift of warm waters in the North Atlantic allows Norway to claim the most northerly localities of boreonemoral plant species in the world. West-east sections of Norway reveal strong changes in vegetation as the oceanic influence is lost and the high interior is reached. Human impact is not neglected in the book, and the cultural landscape receives a section of its own. It is excellently produced and rich in data, but its complex structure means that this atlas is not always as accessible as one might wish.

M.G. Barbour & D.W. Billings (2000) North American Terrestrial Vegetation. 2nd edn. Pp. xi + 708. Cambridge University Press, Cambridge, UK. ISBN 0-521-55027-0. Price £80 (hardback). ISBN 0-521-55986-3. Price £29.95 (paperback).

The first edition of this book (1988) has become the standard account of North America's vegetation, and the second edition has expanded its coverage and revised and updated much information. Particularly welcome are new chapters on wetlands, both freshwater and saline. It is particularly useful to have concise, comparative accounts of North America's northern peatlands, the prairie potholes, Everglades, and the extensive range of marshes. The saline wetland chapter includes both salt marsh and mangrove and is structured in such a way that the two can easily be compared in terms of community structure, succession, zonation, regeneration and response to disturbance. The geographical coverage of the new edition has also been considerably extended. The temperate regions of Mexico and the tropical forests of Central America are now included, as are the islands of the Caribbean and the Hawaiian Island chain. This new edition of a much respected book is a vital addition to the libraries of all who are interested in the vegetation of the New World; it is sad that Dwight Billings did not survive to see its completion.

P. Thomas (2000) Trees: Their Natural History. Pp. ix + 286. Cambridge University Press, Cambridge, UK. ISBN 0-521-45351-8. Price £42.50 (hardback). ISBN 0-521-45963-X. Price £15.95 (paperback).

So varied in taxonomy, architecture and ecology, trees may seem an odd focus for a textbook, but the topic is here demonstrated to be ideal for introducing many of the basic botanical and ecological questions that rise in thoughtful students' minds. Why do leaves come in different shapes and sizes? Why be compound rather than simple? What are the advantages and disadvantages of being evergreen? How high can you grow? How far do roots spread? Why do some trees mast periodically? Why are trees different shapes? How do trees defend themselves? It is refreshing to find a book that asks, and tries to answer, many of the questions that make botany such an exciting subject, and yet avoids the jargon, so dear to botanists, that serves so often to obfuscate. The text is highly readable, even addictive, and there is the added bonus of well chosen reading lists that lead into the primary literature. This is an ideal book for stimulating thought among those commencing botanical studies.