Outline Studies in Ecology – serie

Vegetation dynamics is an important subject. A knowledge and under­ standing of it is central to the science of vegetation management-in grassland, range and nature reserve management, and in aspects of wildlife management, forestry and agricultural crop production. It is also a large and diffuse subject. In a small book such as this I had to be highly selective, and could not do equal justice to all aspects. I have had therefore to condense many examples, and more regrettably, many arguments. While I have tried to present a broad selection of topics and examples, the content inevitably reflects my own special interests and experience. The study of vegetation and its dynamics does not lend itselfto neat and tidy divisions, and the way of allotting material into different chapters here is arbitrary. I have used Chapter I to introduce a number of ideas, beginning with the nature of vegetation in space, then passing to an introduction to the nature of changes in vegetation with time, in particular those generally known as successions. The book also contains a number of asides to the text's central arguments; I hope the reader finds these interesting rather than disconcerting.

The islands of the Pacific and East Indies made an enormous and fateful impact on the minds of Charles Darwin and Alfred Wallace, the fathers of modem evolutionary theory. Since then island floras and faunas have continued to playa central role in the development of evolutionary, and more recently ecological thought. For much ofthis century island ecology was a descriptive science and a wealth of information has been amassed on patterns of species distributions, on the composition of island floras and faunas, on the classification of islands into types such as oceanic and continental, on the taxonomic description of insular species and sub-species and on the adaptations, often bizarre, of island creatures. However, biologists are not satisfied for long with the mere collection of data and the description of patterns, but seek unifying theories. Island ecology was transformed into a predictive science by the publication, in 1967, of MacArthur and Wilson's Theory of Island Biogeography. This, perhaps the most influential book written on island ecology, has been the stimulus for a generation of theoretical ecologists and gifted field workers. The books listed below in the bibliography will indicate to the reader the vast scope of island ecology and the changes in approach that have taken place over the years.

This text on animal pollution dynamics should be of interest to those studying ecology, population dynamics and pest control.

In this small book I have tried to confine myself to the absolute necessities in a field which requires a knowledge of both biology and physics. It is meant as a primer for biological undergraduates. I hope it will lead some of them to further, more advanced, study. It has not been easy to present the subject in so few pages, and I am aware of many omissions. I hope readers will agree that it is best to concentrate on a small number of topics, which together constitute an essay on plant-atmosphere relationships. Advanced students will be able to take the subject further if they look up some of the references. Text books that I particularly recommend are those by Monteith [38] and Campbell [lOO]. If the reader intends to carry out research investigations he should also consult Fritschen and Lloyd [105] for an introduction to instrumentation in environmental biophysics.

This book attempts to summarize what we know about inseet-plant relationships without beeoming too involved with untestable hypo- theses. It is not intended to be eomprehensive and we have deliberately excluded diseussion of aquatie organisms and fungi. Our definition of inseet herbivores is intentionally broad. It includes all inseets whieh feed on plants, although we have emphasized those whieh feed primarily on the photosynthetie tissues. Some referenee is made to seed predation but pollination eeology is excluded. We thank Ors P.H. Smith and M. Luxton for their helpful eommenb on the manuseript but we accept full responsibility for any mistakes whieh may remain. Finally, we thank the various publishers and a uthor~ who gave us permission to use copyright material. 7 I Introduction The net primary produetion of the 300000 speeies of vaseular plant whieh inhabit the dry land surfaee of the earth has been estimated at 9 about 115 x 10 t per annum. This represents a massive resouree potentially available for exploitation by the herbivorous inseets, which themselves probably number in exeess of 500000 species.