Advances in ECOLOGICAL RESEARCH VOLUME 25 This Page Intentionally Left Blank Advances in ECOLOGICAL RESEARCH Edited by M. BEGON Department of Environmental and Evolutionary Biology, University of Liverpool, UK A.H. FITTER Department of Biology, University of York, UK VOLUME 25 ACADEMIC PRESS Harcourt Brace & Company, Publishers London San Diego New York Boston Sydney Tokyo Toronto ACADEMIC PRESS LTD 24/28 Oval Road London NWI 7DX United States Edition published by ACADEMIC PRESS INC. San Diego, CA 92101 Copyright 0 1994 by ACADEMIC PRESS LIMITED AN Rights Reserved No part of this book may be reproduced in any form by photostat, microfilm, or any other means, without written permission from the publishers British Library Cataloguing in Publication Data Advances in ecological research. Vol. 25 1. Ecology I. Begon, Michael 514.5 ISBN 0-12-013925-1 This book is printed on acid-free paper Typeset by Fakenham Photosetting Ltd, Fakenham, Norfolk Printed in Great Britain by T. J. Press (Padstow) Ltd, Padstow, Cornwall Contributors to Volume 25 D. ATKINSON, Population Biology Research Group, Department of Environmental and Evolutionary Biology, University of Liverpool, P. 0. Box 147, Liverpool L69 3BX, UK. M.G.R. CANNELL, Institute of Terrestrial Ecology, Edinburgh Research Station, Bush Estate, Penicuik, Midlothian EH26 OQB, UK. R.C. DEWAR, Institute of Terrestrial Ecology, Edinburgh Research Station, Bush Estate, Penicuik, Midlothian EH26 OQB, UK. S.L. GUTSELL, Division of Ecology, Department of Biological Sciences and the Kananaskis Field Stations, University of Calgary, Calgary, Alberta, Canada 72” I N4. J.S. HANAN, Cooperative Research Centre for Tropical Pest Management, CSIRO Division of Entomology, PB No. 3, Indooroopilly, Q4068, Australia. M.J . HUTCHINGS, School of Biological Sciences, University of Sussex, Falmer, Brighton, Sussex BNl 9QG, UK. E.A . JOHNSON, Division of Ecology, Department of Biological Sciences and the Kananaskis Field Stations, University of Calgary, Calgary, Alberta, Canada T2N 1N4. H. de KROON, Department of Plant Ecology and Evolutionary Biology, University of Utrecht, P. 0. Box 800.84, 3508 TB Utrecht, The Netherlands. L. MAILLETTE, Department of Biological Sciences, University of Calgary, 2500 University Drive, Calgary, Alberta, Canada T2N 1N4. Present address: Dkpartement de Chimie-Biologie, Universite‘ du Qutbec a Trois-Rividres, CP 500, Trois-Rividres, Qutbec, Canada G9A 5H7. P.M. ROOM, Cooperative Research Centre for Tropical Pest Management, CSIRO Division of Entomology, PB No. 3, lndooroopilly, Q4068, A ustralia. This Page Intentionally Left Blank Preface It is to be hoped that the bad old days are far behind us when theoretical ecologists, or ecological modellers, field biologists and other empiricists were warring factions, with a relative few spanning the “cultural” divide. Every one of the contributions to this current volume draws on theoretical and empirical work in moving towards a new synthesis. In the first paper, Atkinson examines data