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

396 Pages·1988·22.33 MB·English

by  R. E. Longton

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
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© 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