Allen Press x DTPro Book Reviews Ecology, 78(1), 1997, pp. 323±324 q 1997 by the Ecological Society of America TROPICAL DRY FORESTS The global perspective is provided by Gentry. On the basis Bullock, Stephen H., Harold A. Mooney, and Ernesto Medina. of 28 sample plots established throughout the world, Gentry 1995. Seasonally dry tropical forests. Cambridge University Press, New York. xvii 1 450 p. ISBN: 0-521-43514-5. concluded that although dry forests are less diverse than wet forests, diversity in dry forests, beyond a certain threshold of precipitation, does not increase with an increase in annual Tropical dry forest, characterized by Dan Janzen as the rainfall. Gentry also noted that although tropical dry forests ``most endangered tropical ecosystem,'' once covered vast share many genera and families with wet forests, species over- tracts of the earth, but now occupies only a very small fraction lap is minimal. Furthermore, various dry forests differ in their of its original area. The species richness of dry forests is not species composition as well as in levels of endemism. He as high as that of humid forests, but these forests are an also pointed out that centers of endemism are not equatorial important reservoir of biodiversity, and a signi®cant source but near the tropics. Thus, efforts to conserve dry forests of goods and services to human societies. The relatively sim- cannot be restricted to a single geographical region. ple structure of dry forests makes them more suitable to un- A number of chapters cover ecosystem processes such as ravel ecological patterns and processes than their wet coun- primary production (MartõÂnez-YrõÂzar, nutrient cycling (Jar- terparts, and indeed, some of the most signi®cant insights amillo and Sanford), nitrogen trace gas emissions (Matson into ecosystem structure and function in the tropics have had and Vitousek), soils (Cuevas) and drought responses (Hol- their basis in research conducted in dry rather than in wet brook, Whitbeck, and Mooney). Some of the common themes forests. However, despite the biological importance of these include comparisons with wet forests, responses to the pro- forests, their intense and prolonged use by humans, and their nounced dry season, and a general lack of information about rapidly diminishing size, not a single book exclusively de- basic processes. However, the authors and editors do not take voted to the ecology of the dry forests has been available advantage of the opportunity to address a common set of until the publication of this volume. This book, edited by conceptual issues concerning ecosystem processes. Stephen Bullock, Harold Mooney, and Ernesto Medina, rep- Species interactions is the topic of two chapters: plant re- resents the output of a symposium held at the EstacioÂn de production (Bullock) and plant-herbivore interactions (Dirzo BiologõÂa Chamela, Jalisco, MeÂxico. The date of the sympo- and Dominguez). Bullock's masterful review of various as- sium is not speci®ed, but most papers seem to be current, as pects of reproduction, including phenology, pollination, seed indicated by their list of references. dispersal, and mating patterns brings together a wealth of The papers can be grouped into four broad categories. The information. This is by far the most comprehensive chapter ®rst category includes reviews with emphasis on the structure in the book, with the longest list of citations. The chapter on and general features of dry forests in different parts of the plant-herbivore interactions is a useful documentation of world; the other categories are ecosystem processes, includ- community and population level patterns and the conse- ing species interactions, conversion, and ethnobotany. Most quences of herbivory. papers deal with Central American forests, acknowledged by Animal diversity is the subject of only one chapter on ver- the editors as the focal region of the book. However, there tebrates by Ceballos; the editors comment on a lack of in- are some chapters from Asia and Africa. Moreover, references formation on invertebrates. to work in all tropical regions of the world are scattered Maass explores the causes and consequences of conversion throughout most chapters. of tropical dry forests into other types of land uses and, like Perspective on the structure and composition of dry forests others, pleads for more research on sustainable land use in are provided for Central America and the Caribbean (Murphy areas occupied by tropical dry forests. Much of the tropical and Lugo), Brazilian caatinga (Sampaio), Africa (Menaut, dry forest has been converted to pasture and agriculture. Thus, Lepage and Abbadie) and Thailand (Rundel and Boonpra- unless the economic consequences of conversion on other gob). Diversity of life forms is a separate topic in the chapter land uses, particularly agriculture, are fully explored, pleas by Medina. These chapters highlight several features: tropical for sustainable land use are not likely to receive much atten- dry forests are less diverse than wet forests; total biomass of tion. trees and net annual primary productivity are also lower, but In the ®nal chapter, Bye brie¯y comments on the economic the diversity of plant life forms is greater; and the human uses of plants in tropical dry forests of Mexico. He lists a impact is intense. number of plant species that are harvested and provides eco- Complementing these studies of contemporary forests, logical and economic data for these taxa. Tropical dry forests Graham and Dilcher describe changes in the composition of have been extensively used by humans for millennia and offer the plant communities in the Americas based on the fossil a rich source of material for ecological and economic anal- pollen record. Dry forest elements ®rst appear in Mid to Late yses. However, Bye, like several others in the volume, misses Eocene, increase in diversity through Mid Tertiary, and can the opportunity to address central questions about how the be recognized as a part of a distinct community in the Mio- extent of use might be linked to the enhancement of rural cene/Pliocene. incomes and conservation. 323 Tuesday Sep 15 05:11 PM ecol 78 205 Mp 324 Allen Press x DTPro File # 10tx 324 BOOK REVIEWS Ecology, Vol. 78, No. 1 Overall, this volume brings together, for the ®rst time, con- much we are likely to miss his contributions to tropical ecol- siderable information about structure, function, and human ogy. Gentry inspired and challenged his colleagues to look use of tropical dry forests. Thus the book should be of im- for patterns and to seek explanations for these patterns. This mense value to ecologists throughout the world. Its value volume keeps alive Gentry's spirit and provides a glimpse of could have been enhanced if the editors had taken a little the challenges and opportunities that dry tropical forests offer more time to provide a conceptual framework for various to ecologists and conservation biologists. topics and to pose questions for future work. The introductory KAMAL BAWA comments by the editors are very insightful, and readers could University of Massachusetts, Boston have bene®tted from more detailed commentaries. Department of Biology The book is dedicated to Alwyn Gentry, whose paper in 100 Morrissey Blvd. the volume demonstrates how insightful he was, and how Boston, Massachusetts 02125 Ecology, 78(1), 1997, pp. 324±326 q 1997 by the Ecological Society of America ENSURING ECOLOGICAL DIVERSITY ernment offers the appropriate skill and framework to ensure Snape, William J., III (ed.). 1996. Biodiversity and the law. and protect biological diversity throughout the future. Island Press; Washington, D.C. xxvii 1 259 p. $49.00 (cloth), ISBN: 1-55963-394-8 (acid-free paper); $25.00 (paper), In the book's Foreword, Oliver Houck calls the concept of ISBN: 1-55963-395-6 (acid-free paper). ``biological diversity'' the new organizing principle for life on earth. While the concept deserves close scrutiny as an organizing precept, Houck sees three problems preventing As noted conservationist Aldo Leopold concluded in A biodiversity from becoming the key framework: ®rst, the lack Sand County almanac, the ®rst rule of intelligent tinkering is of precision on what constitutes biological diversity; second, to save every cog and wheel. The current legal and political the lack of public awareness on what diversity actually is, approach for managing biological diversity, however, violates and, third, the lack of mechanisms for incorporating the idea that rule. Today, virtually every element of the natural en- into human institutions so that, over time, life on earth re- vironment is being lost: species decline, communities decline, mains biologically diverse. The problem with biodiversity as habitats dwindle, and ecosystems disappear. The current a legal and social concept, Houck concludes, is that in a world framework for assuring a biological future, in short, does not rife with streetshootings, grinding inequality and ethnic wars work, and the prospects of life without diversity should trou- of extermination, it is hard to get worked up over ``ecosys- ble even the most positive idealists. As anyone beyond the tems.'' third grade knows, a world without diversity is a world with- Following Houck's wise take on the current situation, the out life. book's ®rst of four parts reviews the scienti®c and policy Snape makes sense of these dif®cult issues with a collection foundations of biodiversity and the law. Here, Molly Beattie, of ®rst-rate articles and essays on biological diversity law Director of the U.S. Fish and Wildlife Service, reviews the and policy. Snape's effort, a result of a Defenders of Wildlife U.S. government's view of biodiversity and ecosystem man- conference held in March 1994, is not a typical legal treatise agement, but provides no persuasive evidence that the gov- with nth-order footnotes and elegant, but impractical legal ernment's acts will make any progress toward these goals.