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Biology of Polar Bryophytes and Lichens (Studies in Polar Research) PDF

396 Pages·1988·22.33 MB·English
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The biology of polar bryophytes and lichens Studies in Polar Research This series of publications reflects the growth of research activity in and about the polar regions, and provides a means of synthesising the results. Coverage is international and interdisciplinary: the books are relatively short and fully illustrated. Most are surveys of the present state of knowledge in a given subject rather than research reports, conference proceedings or collected papers. The scope of the series is wide and includes studies in all the biological, physical and social sciences. Editorial Board A. Clarke, British Antarctic Survey, Cambridge D. J. Drewry, British Antarctic Survey, Cambridge S. W. Greene, Department of Botany, University of Reading P. Wadhams, Scott Polar Research Institute, Cambridge D. W. H. Walton (chairman), British Antarctic Survey, Cambridge P. J. Williams, Geotechnical Science Laboratory, Carleton University, Ottawa Other titles in the series G. Deacon, The Antarctic Circumpolar Ocean Y. I. Chernov, transl. D. Love, The Living Tundra* B. Stonehouse (ed.), Arctic Air Pollution G. Triggs (ed.), The Antarctic Treaty Regime Sir Anthony Parsons (ed.), Antarctica: The Next Decade Francisco Orrego Vicuna, Antarctic Mineral Exploitation: The Emerging Legal Framework C. Lamson and D. Vanderzwaag (eds.), Transit Management in the Northwest Passage Donat Pharand, Canada's Arctic Waters in International Law V. Aleksandrova, transl. D. Love, Vegetation of the Soviet Polar Deserts Nigel Leader-Williams, Reindeer on South Georgia: The Ecology of an Introduced Population * Also available in paperback. The biology of polar bryophytes and lichens R. E. LONGTON Department of Botany School of Plant Sciences, University of Reading PUBLISHED IN ASSOCIATION WITH THE BRITISH BRYOLOGICAL SOCIETY The right of the University of Cambridge to print and sell all manner of books was granted by Henry VIII in 1534. The University has printed and published continuously since 1584. CAMBRIDGE UNIVERSITY PRESS Cambridge New York New Rochelle Melbourne Sydney CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, Sao Paulo, Delhi Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org/9780521250153 © Cambridge University Press 1988 This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 1988 This digitally printed version 2008 A catalogue record for this publication is available from the British Library Library of Congress Cataloguing in Publication data Longton, R. E. The biology of polar bryophytes and lichens/R. E. Longton. p. cm. Bibliography. Includes index. ISBN 0-521-25015-3 1. Bryophytes - Polar regions. 2. Lichens - Polar regions. I. Title. QK533.84.P73L66 1988 588'.0998-dc 19 88-1095 ISBN 978-0-521-25015-3 hardback ISBN 978-0-521-09338-5 paperback Contents Preface page vii The polar regions 1 Topography and geological history 1 Climate 7 Soils 12 Vegetation types and zones 13 Polar bryophyte and lichen floras 23 The cryptogamic vegetation 32 Vegetation classification 32 Cryptogamic growth form types 34 Vegetation in the cold-Antarctic 37 Vegetation in the cold-Arctic 47 Vegetation in the frigid-Antarctic 49 Vegetation in mild and cool-polar regions 52 Benthic bryophytes 64 Pattern, process and environment 66 Environmental relationships of polar cryptogamic vegetation 66 Colonisation and succession 79 Pattern in polar vegetation 94 Radiation and microclimate 106 Solar radiation 106 Net radiation 116 Energy budgets 117 Annual temperature regimes 131 Physiological processes and response to stress 141 Environmental control of carbon dioxide exchange 141 Net assimilation rate under field conditions 185 Response to plastic stress 192 Adaptation and selection 203 Vegetative growth 211 Patterns of growth in relation to net assimilation and translocation 211 Vegetative phenology and annual growth increments 229 Environmental and inherent control of growth 246 vi Contents Cryptogams in polar ecosystems 253 Energy flow 253 Nutrient cycling 290 Other effects of bryophytes and lichens 298 Human influence on polar cryptogams 299 Reproductive biology and evolution 310 Reproductive processes and propagules 310 Reproduction in polar species 313 Reproductive phenology 316 Failure in sexual reproduction 319 Dispersal and establishment 323 Life history strategies 331 Origin and evolution of polar cryptogamic floras 335 Concluding remarks 341 References 343 Index of generic and specific names 383 Subject index 386 Preface This book is about bryophytes and lichens in the Arctic and Antarctic. It considers the evolution and adaptations of the polar floras, and the role of these plants in the vegetation and in the functioning of tundra ecosystems. The study of plant ecology in the polar regions has advanced dramatically in recent years as a result of work initiated in the Antarctic during the International Geophysical Year (1957-58), and in both Arctic and Antarctic as part of the International Biological Programme Tundra Biome investigations. Much attention has been focused on bryophytes and lichens because of their obvious abundance in local communities. The work has been broad in scope, ranging from phytogeography to physiological ecology, and from vegetation ecology to reproductive bio- logy. The results, as synthesised here, are of relevance far beyond the polar regions, because they make a substantial contribution towards a general understanding of the environmental relationships of bryophytes and lichens. It should be noted, however, that mosses are of considerably greater ecological significance in the tundra than liverworts; they have consequently received more emphasis in research and therefore in the present text. Authorities for most of the plant names cited in the text can be found in the following: mosses - D. M. Greene (1986), Steere (1978a); hepatics - Schuster (1966-80), Grolle (1972); lichens - Thomson (1984), Lindsay (1974); vascular plants - Greene & Walton (1975), Scoggan (1978-79). Where differences occur, the nomenclature used by the first-mentioned authority for each group has been followed. The present author's work in polar ecology has been supported finan- cially and/or logistically by the British Antarctic Survey, the United States Antarctic Research Program, the Royal Air Force Mountaineering Association, the National Science and Engineering Research Council of Canada, the Natural Environment Research Council (UK), and the viii Preface University of Manitoba Northern Studies Committee: it has been depen- dent on facilities generously provided in the Departments of Botany in the Universities of Birmingham, Manitoba and Reading. Grateful ack- nowledgement is made to these organisations, and to the many colleagues with whom stimulating and enjoyable discussion has helped to formulate my ideas on the topics considered here, including Drs L. C. Bliss, T. V. Callaghan, N. J. Collins, D. L. Hawksworth, D. C. Lindsay, G. A. Llano, D. M. Moore, W. O. Pruitt, R. I. Lewis Smith, J. M. Stewart, D. H. Vitt and D. W. H. Walton. I am particularly grateful to Dr S. W. Greene for advice and encouragement over many years, and to Dr D. H. Brown and Professor P. Kallio for reading a draft of the present manuscript; their comments and suggestions have materially improved the final product without being in any way responsible for whatever defi- ciencies remain. I also thank Dr R. I. Lewis Smith for supplying the photographs for Figs. 1.6, 2.1, 2.5, 3.3 and 6.12, J. D. Ives for Fig. 1.3, Dr F. J. A. Daniels for Fig. 2.10, and Mr S. Brooks and Mr D. J. Farmer for assistance in preparing the other illustrations. Finally, I thank my family who have cheerfully endured long periods when I have been out of communication, either working at some remote polar station or closeted in the study. They have never complained; well, hardly ever! R. E. Longton Reading, December 1986 1 The polar regions Topography and geological history This book considers the biology of bryophytes and lichens in polar tundra and adjacent, open woodland, their contribution to the vegetation, their role in polar ecosystems, and their adaptations to the rigours of life in regions generally regarded as among the least hospitable on earth. Tundra is used here in the broad sense of treeless regions beyond climatic timberlines. It occurs in the polar regions as defined in Figs. 1.1 and 1.2, and in some alpine and oceanic areas at lower latitudes. The polar regions are diverse in topography and climate. Arctic lands comprise substantial parts of the North American and Eurasian continents which, with Greenland and smaller islands, encircle a polar ocean (Fig. 1.1). The terrain ranges from extensive flat-bedded plains and plateaus to folded mountains, often high and imposing as in the Brooks Range, Alaska, where elevations reach over 2800 m (Figs. 1.3 and 1.4). Except in Greenland, contemporary glaciation is localised, and largely confined to Spitzbergen and other far-northern islands. In contrast, the Antarctic continent is centred over the pole and is surrounded by the vast expanse of the Southern Ocean, with a minimum width of over 850 km between the Antarctic Peninsula and Cape Horn (Fig. 1.2). The continent is fringed by coastal mountains, and rises to an inland ice-plateau at elevations of 1800 to 3800 m. Over 98% is currently buried beneath an ice sheet more than 4 km thick in places. Islands lying close by the mainland or widely scattered in the Southern Ocean thus provide the major terrestrial habitats in Antarctic regions, where vegetation is restricted to the almost universally rugged terrain of coastal regions, and to nunataks penetrating the inland ice sheet (Figs. 1.5 and 1.6). The highest, Mt Kirkpatrick, reaches an altitude of about 4500 m. Arctic lands were formerly part of Laurasia, and although their pos- itions have shifted as a result of continental drift, it is unlikely that the

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This book reviews the biology of bryophytes and lichens in the polar tundra, where these plants may form a dominant component of the vegetation. It considers adaptation to severe environments in terms of growth form, physiology and reproduction. The role of bryophytes and lichens is discussed in veg
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