ECOLOGY AND BIOGEOGRAPHY IN SRI LANKA MONOGRAPHIAE BIOLOGICAE VOLUME 57 Series Editor H.J. Dumont 1984 DR W. JUNK PUBLISHERS a member of the KLUWER ACADEMIC PUBLISHERS GROUP THE HAGUE / BOSTON / LANCASTER ECOLOGY AND BIOGEOGRAPHY IN SRI LANKA Edited by C. H. FERNANDO 1984 DR W. JUNK PUBLISHERS a member of the KLUWER ACADEMIC PUBLISHERS GROUP THE HAGUE / BOSTON / LANCASTER Distributors for the United States and Canada: Kluwer Academic Publishers, 190 Old Derby Street, Hingham, MA 02043, USA for the UK and Ireland: Kluwer Academic Publishers, MTP Press Limited, Falcon House, Queen Square, Lancaster LA1 1RN, England for all other countries: Kluwer Academic Publishers Group, Distribution Center, P.O. Box 322, 3300 AH Dordrecht, The Netherlands Library of Congress Cataloging in Publication Data Main entry under title: Ecology and biogeography of Sri Lanka. (Monographie biologicae ; v. 57) Includes bibliographies. 1. Ecology--Sri Lanka. 2. Biogeography--Sri Lanka. I. Fernando, C. H. II. Series. OPl.P37 vol. 57 [r:H183.5J 5748 [574.5 ',,9549',1 8,-?6784 ISBN -13: 978-94-009-6547-8 e-ISBN -13: 978-94-009-6545-4 DOl: 10.1007/978-94-009-6545-4 ISBN-13:978-94-009-6547-8 Copyright © 1984 by Martinus Nijhoff Publishers, The Hague. Softcover reprint of the hardcover 1st edition 1984 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publishers, Martinus Nijhoff Publishers, P.O. Box 566, 2501 eN The Hague, The Netherlands. Preface When the late Professor Joachim Illies suggested in 1980 that I edit a volume of the Monographiae Biologicae on Sri Lanka, I was glad to accept the challenge. Although I had spent only six years of my research and teaching career in Sri Lanka, I had made personal contact or corresponded with many scientists who had worked in, still work in, or who have studied material from Sri Lanka. The present domicile of the authors of the chapters in this volume shows the wide geographic spread of interest in Sri Lanka, and indicates also the dispersion of Sri Lankan scientists like myself. Sri Lanka has had a relatively long history of indigenous scientific research in the natural sciences. From the early work of Kelaart (1852, Prodromous Fauna Zeylanicae, Ceylon Govt. Press, 250 pp.) to the present time, there has been a more or less sustained research effort in the natural sciences. The Colombo Museum, which celebrated its centenary only a few years ago, and the world famous Peradeniya Botanical Gardens, served as repositories and bases for continued research on the fauna and flora. There are a number of land marks in these studies. Linnaeus' (1747) Flora Zeylanica, which was based on the collection of a German Physician and Botanist, Paul Hermann, was the first notable contribution. The monumental work of Trimen (1839-1900, A Handbook to the Flora of Ceylon, Vol. 1-5) has not yet been fully superseded. Tennant (1891) gave a fairly detailed account of many animals, and lists of fishes and insects. The vertebrates have received detailed attention from researchers working mainly in the Colombo Museum. There are reliable and up to date monographs on the fishes by I.S.R. Munro (1955), amphibians by P. Kirtisinghe (1957), birds by G. M. Henry (1955) and mammals by W.W.A. Philips (1935). P.E.P. Deraniyagala, in his long career at the Colombo Museum, made many contributions to the systematics of fishes and reptiles, and palaeontological studies on mammals. P.H.D.H. de Silva, who succeeded Deraniyagala, carried on this work, and recently published a monograph on the snakes. The publication of' A guide to the freshwater fauna of Ceylon' by Mendis & Fernando (1962) was the first for any tropical country encompassing the whole spectrum of freshwater fauna with a listing of species. This work has been updated with four supplements. VI Commercial interests have contributed to the study of the living organisms from a relatively early date. Herdman (1903, Report to the Government by Ceylon on the Pearl Oyster fishery offthe gulf of Manaar. Roy. Soc. Lond. 1: 1-146) was one of the earliest such contributors. The work of the Tea, Rubber and Coconut Research Institutes, the Agricultural and Medical Research Institutes and the Department of Fisheries contributed much to the study of living organisms of economic importance which could be exploited or were pests of economically important plants and animals. Sri Lanka, called Serendib, Taprobane and later Ceylon, has from very early times attracted the attention of many travellers, among them naturalists and scientists. Because of its small size, explorers have not been involved in 'discover ing' the country, which was settled fairly densely around 600 B.c. Sri Lanka has a land area of only 65,000 km2• It's latitudinal position(6-100N) is clearly in the equatorial zone, but the climate in the mountains (to 2,300 m) is almost 'temperate'. The dry and wet zones mark the major climate division but within these zones are many gradations. Although geologically not very varied, soils, altitude and rainfall have combined to give Sri Lanka a wide variety of topography and vegetation. The range of climates in Sri Lanka is unrivalled for a country of its size. A major feature of the natural landscape is the abundance of rivers and streams. Human enterprise has added another feature which is equally striking, namely the man-made lakes, of which there are >10,000. These reservoirs comprised a sophis ticated irrigation system for rice cultivation in ancient times. It is mainly restricted to the dry zone. This irrigation system supported a resilient civilization (600 B.C.-1200 A.D.) and a peak popUlation of about 6 million, a very high carrying capacity for that time. Since then Sri Lanka has undergone profound environmen tal changes due to dense human settlement; first in the foothills, followed by plantation agriculture in the highlands, urbanization ofthe lowlands and a revitali zation of the agriculture of the dry zone. The impact of high human densities on grasslands, forests, water resources and the flora and fauna in general has been very pervasive. This volume refers to some of the effects of these high human densities. In preparing this volume I have endeavoured to cover as wide a range of subjects as possible. It was also my intention to invite both senior and junior scientists to contribute. I was sorry that some potential contributors who had done extensive work in Sri Lanka, notably Professors D. Mueller-Dombois, Honolulu; Per Brinck, Lund; B.A. Abeywickrema, Colombo and Drs. R. Fosberg and K.V. Krombein, Washington, were already heavily committed to other work. However, the contributors I have been able to assemble come from a wide spectrum of disciplines and backgrounds. This volume consists of 22 chapters. The three chapters dealing with geology, land forms and geochemistry set the stage for later chapters which include vegeta tion, aquatic fauna, terrestrial fauna and human impact. Besides the systematics VII and ecology of a wide range of faunal groups, certain specific environments have been dealt with in detail, e.g. grasslands and ricefields, both heavily influenced by human settlements, and rocky shores and lagoons. A recurring theme is the high endemicity in some groups of organisms. Only one chapter, however, deals with this subject specifically. Sri Lanka also is a well researched area for the role of ecological factors on parasitic diseases. A chapter is devoted to this subject. Another theme in several chapters is the effect of high human densities; the final chapter, on settlements, is devoted to this subject. The emphasis on freshwater may be a reflection of my own speciality. However, this biotope has received a relatively high level of scientific attention in recent years because of the perceived danger of irreversible pollution and the prospects of harvesting fish from inland waters. I received much help and co-operation from the authors. Mrs Dawn Sephton assisted me in editing, as did Dr Russell Shiel, who also put the chapters into final form on a word processor. This volume should interest a very wide audience, both professional and non professional. There is a great deal of information and syntheses useful to biologists, agricultural scientists, environmental biologists and medical scientists. There is a substantial body of information on the flora and fauna, on the ecology of a wide range of habitats, and on the impact of humans on the environment. VIII To A. C. J. Weerekoon, a bold and innovative biologist and a courageous person IX Addresses of Authors K.D. Arudpragasam, Department of Zoology, University of Colombo, P.O. Box 1490, Colombo 3, Sri Lanka. P.G. Cooray, Institute of Applied Geology, King Abdulaziz University, P.O. Box 1744, leddah, Saudi Arabia. H.H. Costa, Department of Zoology, University of Kelaniya, Kelaniya, Sri Lanka. H. Crusz, Department of Zoology, University of Peradeniya, Peradeniya, Sri Lanka. D.M. Davies, Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada, L8S 4KI. C.D. de Silva, Department of Zoology, Ruhuna University College, Medawatte, Matara, Sri Lanka. S.S. de Silva, Department of Zoology, Ruhuna University College, Medawatte, Matara, Sri Lanka. A.S. Dissanaike, Parasitic Diseases Programme, World Health Organization, 121 I Geneva 27, Switzerland. C. B. Dissanayake, Department of Geology, University of Peradeniya, Peradeniya, Sri Lanka. O.K. Erb, Department of Geography, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G I. T.L. Erwin, Curator, Coleoptera, National Museum of Natural History, Smith sonian Institute, Washington, D.C. 20560, U.S.A. C. H. Fernando, Department of Biology, University of Waterloo, Waterloo, Onta rio, Canada, N2L 3G I. A.V. Gussev, Zoological Institute, Academy of Sciences, Leningrad, B-I64, U.S.S.R. M. D. Hubbard, Department of Entomology, Florida A & M University, College of Science and Technology, Tallahassee, Florida 32307, U.S.A. G.M. McKay, School of Biological Sciences, Macquarie University, North Ryde, New South Wales, 2113, Australia. l.W. Neale, Department of Geology, University of Hull, Hull, HU6 7R, England M.A. Pemadasa, Department of Botany, Ruhuna University College, Medawatte, Matara, Sri Lanka. x N.P. Perera, FAO Land Use Planning Unit, UNDP, P.O. Box 301, Maseru, Lesotho. W.L. Peters, Department of Entomology, Florida A & M University, College of Science and Technology, Tallahassee, Florida 32307, U.S.A. R. Rajapaksa, Department of Biology, University of Waterloo, Waterloo, Onta rio, Canada, N2L 3G I. R. Ratnapala, Anti-Malaria Campaign, Colombo 5, Sri Lanka. F. Starmtihlner, 11 Zoologisches Institut der UniversiUit Wien, A-101O Karl Lueger Ring 1, Vienna, Austria. S. Weeraratna, Department of Agronomy, Faculty of Agriculture, Ruhuna Uni versity College, Mapalana, Matara, Sri Lanka.