Book Reviews: Ecological

Feeding the Ten Billion; Plants and Population Growth Evans, L.T., 1998. ISBN 0-521-64685-5 (paper US$19.95) ISBN 0-521-64081-4 (cloth US$54.95) 247 pp. Cambridge University Press, 40 West 20th St., New York, NY 10011-4211 - Lloyd Evans is an outstanding Australian crop physiologist who is a 'despairing optimist' about the coming half century in which, if current trends hold, the world population will more than reach 10 billion people.

This book, however, is not so much a look to the future as an account of how we got to 6 billion humans in 1999. The first 5 chapters get us up to the first billion, about 1825, with a history of traditional agriculture in both hemispheres. Domestication, maintaining fertility, irrigation practice, all get notice. Then we have 5 chapters recounting the events leading to the 2nd billion (1925), 3rd billion (1960), 4th billion (1975), 5th billion (1986), and 6th billion (1999). Note the shortening of the doubling time! Important factors in feeding us in this period, are: increases in cultivated land, new varieties, and industrial inputs (fertilizer, irrigation, pesticides, internal combustion engines). Since 1960, increases in farm land have been negligible, and the greatly increased production (of cereals) has been due to greater yields per hectare.

This book is to be recommended principally for its wealth of information on world agricultural production. Although not all statements are referenced, there are 228 items cited, many to agency documents. Each chapter has an introduction, followed by discussion of the subjects in more detail.

A recurring theme is the question of what drives population growth and agricultural innovation. The Malthusian view is that better agriculture permits population growth; the view of Ester Boserup is that population growth drives agricultural development. Evans thinks both are partial truths. In fact, his book seems to be an attempt to justify to Boserup's view in the future. Yet it is hard to imagine population outrunning agriculture.

The future does look bleak. There is not much chance for significant increases in cultivated land (unless one includes sea-water irrigated halophytes, a subject not mentioned here). More fresh-water irrigated land does not seem likely, in view of competing demands on that water. Without such increases, the average cereal yield for the world as a whole would have to be about 5.0 tons per hectare, a value not yet reached (on the average) in either Europe or North America. Climate change (global warming) may intrude further difficulties. Evans suggests that one possible development would be a increase in the efficiency of Rubisco, the enzyme responsible for carbon dioxide fixation. Nearly four billion years of fierce competition have not eliminated the inefficiencies of that enzyme, however. The strategies land plants have had to resort to avoid or repair photorespiration testify to the difficulty of this problem.

Evans mentions, in passing, concerns about environmental degradation, reduction in biodiversity and other negatives, but does not devote much space to them. He spends more time on poverty, but has no particular solution to the problem of providing food to the very poor, except trickle-down development. One factor inhibiting increases in food for people is that the trend now is for more meat in the diet, meaning that more of the cereals will be used for animals in the future, not less. Evans also does not consider the social negatives of crowding. The history of nations and ethnic groups does not make me optimistic that civil conflict or outright war over territory will go away.

Finally, to bring the whole into perspective, he mentions projections of 'How many people can the earth support?' Of 64 such estimates, one fourth are less than the present population and another fourth are between 6 and 10 billion. That leaves another half, ranging upward to 1000 billion! As I used to tell my students, 'figures don't lie, but liars figure.'

What is the chance that we will not have to 'feed the ten billion'? There are places where the birth rate has fallen dramatically, Bangladesh for one. China has had a 1 child policy to try to bring their population to stability. Nevertheless, I have little hope that the demographic transition will occur tomorrow in Africa or India. So maybe it won't be ten billion, but only eight. It is still not a rosy future. —John H. McClendon, Professor of Biology emeritus, University of Nebraska; 105 Bush St., Ashland OR 97520.

Florida Wildflowers in Their Natural Communities Taylor, Walter Kingsley 1998. ISBN 0-8130-1616-9 (paper US$24.95) 370 pp University Press of Florida, 15 Northwest 15th Street, Gainesville, FL 32611-2079. - An important addition to a southeastern botanist's bookshelf is Walter Kingsley Taylor's new book, Florida Wildflowers in Their Natural Communities. This book provides a concise introduction to Florida and flower identification, and then a brief, readable description of Florida's major terrestrial communities. The major part of the book is made up of extensively illustrated sections on each of these major communities. Each section begins with some habitat pictures, prior to a cavalcade of beautiful close-up photos of individual species, for which Taylor is already well known (his previous book, Florida Wildflowers, has been extensively utilized and enjoyed by many). The photos are clear, beautiful, and extremely helpful in determining common plants with ease.

Taylor has included most of the common species of each habitat, as well as some of the unusual and interesting. It is not yet possible to find a completely useful flora of this state (Richard Wunderlin's (1998) Guide to the Vascular Plants of Florida is great for nomenclature, but has neither complete species descriptions nor illustrations), so supplemental books with pictures are extremely valuable. Because some species occur in a variety of habitats, and these species are often repeated in Taylor's new book, the total number of species included are fewer than his previous wildflower book. But, some may argue, they are more usefully arranged in this volume, though I always like to see pictures of species of which I am unsure.

There are a few errors in the text, such as: Hurricane Andrew in March 1994 (it was August 1992); a photo of Morinda royoc (Rubiaceae) being misidentified as Sideroxylon salicifolium (Sapotaceae); the distribution of a species reputedly 'S. Florida throughout, except Monroe. Found in the Keys.' (Monroe County IS the Keys!) And a common misconception promulgated: white stopper (Eugenia axillaris) smells much stronger/worse than Spanish stopper (E. foetida), contrary to what the names suggest! With a little more thought, the author could have included some useful characters for distinguishing among common congeners, such as Ficus citrifolia and Ficus aurea. But these shortcomings are minor, and I only felt I need to include them to show I really did read the book!

A botanical or natural history visitor to the state would do well to use this book as a guide to seeing examples of all these habitats. It will be a nice complement to the somewhat more scholarly Ecosystems of Florida for our course in Florida Plant Communities, and I know the students will appreciate its organization as we visit the different habitats on our field trips. —Suzanne Koptur, Florida International University, Miami

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