Ecology and tropical biology

Ecology and tropical biology

TREE vol. 1, no. 4, October 1986 used, to veriw, trace and define the active constituents and finally to work out whether the plant extracts or isola...

158KB Sizes 8 Downloads 423 Views

TREE vol. 1, no. 4, October 1986

used, to veriw, trace and define the active constituents and finally to work out whether the plant extracts or isolated compounds can safely be employed and if so how they are best presented to the user. Considerable efforts to develop such teams are being made in Nigeria, Kenya, Tanzania and some of the francophone states of West Africa, notably Cameroon. Here groups which encompass some, occasionally most, of the above disciplines are enthusiastic and dedicated but generally lack funds. Sadly for the chemists and pharmacologists, their

expensive Western educations have usually been far too specialised and have left them unprepared for the wide spectrum of non-sophisticated techniques that these studies require in the first instance. Recently I was involved in such a team in a specific search for antiimplantation drugs of plant origin. This collaboration led to the identification of a highly active compound, the maximum natural yield of which was 50 p.p.m. (it has since been synthesized). The plant involved is rather toxic due to the presence of other compounds at far

higher levels and was not identified by its traditional use but by very painstaking bioassay procedures. Thus whilst medicinal plants are an obvious place to start, it must never be forgotten that there are a far greater number of non-medicinal plants, not utilised for any one of a number of different reasons, which might also hold valuable natural products. Peter G. Waterman PhytochemistryResearchLaboratories,University of Strathclyde,GlasgowGl IXW, UK.

A TropicalText Ecologyand Tropical Biology by Ian Deshmukh, Blackwell, f16.95 pbk (xii + 387 pages) 0865423144

1986, ISBN

Ecology has strong tropical antecedents. The foundations of modern ecology were laid in the 19th century by the travelling natural historians, among them Humboldt, Darwin, Wallace and Bates, whose contributions to science derived mainly from their tropical experience. Throughout much of the 20th century, however, most ecological theory and practice has been due to north temperate experience, while tropical biology, with few exceptions, progressed quietly as an exercise in collection, classification and description. Well into the 1960s. the contents of the leading ecological journals were only occasionally punctuated by tropical contributions, and much of the genuinely valuable tropical work generated by ‘applied’ studies of forestry, agriculture and pest control remained the province of government and technical reports. In the last two decades, however, there has been a modest explosion (the qualification is necessary, since the percentage of tropical papers in the ecological literature is still in single figures) of interest in tropical ecology, assisted by the increased facility of travel and the growth of institutes of higher education and research in tropical countries. Much of the recent research has, directly or revolved indirectly, around the vexed question of the enormous diversity of tropical organisms. Explanations for high diversity abound, especially for tropical rain forests, though it is remarkable how often such explanations are advanced in the absence of any quantitative information. Behind much of this work

there has lurked the suspicion that the tropics, because they are so obviously different from temperate regions in their complement of taxa, might also be subject to a different set of ecological and evolutionary laws. Throughout his densely-packed and comprehensive new textbook, Ian Deshmukh keeps an eye on the possible differences. Are tropical populations and communities more stable than temperate ones? Are interspecific interactions more intense in the tropics? Does evolution in the tropics differ from evolution elsewhere? For the sceptic, Deshmukh’s answers are encouraging. His book shows that it is now possible to produce what should be the standard list of contents for a modern ecology text, relying almost wholly on tropical examples. In the first part of the book (on the ecology of natural systems) there are chapters on energy flow, nutrient cycling, population ecology, evolutionary ecology and community ecology: they show convincingly that the differences in detail are not generally accompanied by substantial differences in process. The 19th century naturalists would probably not have been surprised. At the level of general principles, there are hardly any major ecological or evolutionary phenomena restricted to the tropics (mutualism is a possible exception, but even this is arguably a matter of definition); the real difference lies in the wealth of biological material from which to extract and refine such principles. Deshmukh rightly points to those areas where data are lacking; in particular, there is still a comparative dearth of long-term studies of population and community dynamics, and the book should help to encourage more research of this kind.

It is in the second

part

of the book

(on human ecology) that the peculiar problems of the tropics become apparent. These three chapters, on agroecosystems, human populations and conservation, should also lay to rest any lingering notion that the study of ‘natural’, human-free ecosystems is somehow more respectable scientifically and rewarding than to attempt to come to grips with the appalling prognosis faced by much of the tropics and its peoples. Deshmukh goes to some lengths to explain, without resort to advocacy, the integral part of human societies in tropical ecosystems; indeed, one suspects that he might have preferred to write the book without the artificial division into a ‘natural’ and a ‘human’ section. Here he describes the traditional tropical subsistence systems, and the often damaging effects of the imposition of temperate ‘industrial’ agricultural systems on tropical lands, and underlines the need for careful integration of traditional and modern systems, based on sound ecological and cultural considerations. Many tropical countries face the twin problems of population growth and disease, in sharp contrast to almost all temperate regions. Deshmukh’s treatment of both problems, the latter especially, is an instructive model for future ecological texts. Deshmukh wrote his book with the aim of providing a thoroughly up to date and comprehensive introduction to tropical ecology for undergraduates (one must hope for translations, at least into Spanish, French and Portuguese, if the book is to reach its intended wide audience of students in tropical countries). The 500+ references are overwhelmingly recent, a welcome testimony to the amount the last

of research conducted decade. Furthermore,

over there

111

TREE vol. 1, no. 4, October 1986

is little geographical bias; Deshmukh chooses his examples from all parts of the tropics. One would have liked, nevertheless, to see some more detail about methodology, experimental design and the practical difficulties involved in tropical fieldwork. In the case of the measurement of species diver-

112

sity, for instance, Deshmukh dwells on models and theoretical approaches without mentioning the taxonomic and logistic problems of counting and identifying all the speties in, say, half a hectare of rain forest, let alone assessing their relative abundance. The student could be forgiven, after reading this

account, for thinking that taxonomy is a thing of the past; in fact, it has as much to contribute to tropical ecology as it had when Humboldt set sail for the Americas in 1799.

Andrew Sugden Editor