ECOLOGY OF HALOPHYTES edited by ROBERT J. REIMOLD University of Georgia Marine Institute Sapelo Island, Georgia WILLIAM H. QUEEN Chesapeake Research Consortium University of Maryland College Park, Maryland ACADEMIC PRESS, INC. New York and London 1974 A Subsidiary of Hareour't Brace Jovanouich, Publishers COPYRIGHT © 1974, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED. NO PART OF THIS PUBLICATION MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS, ELECTRONIC OR MECHANICAL, INCLUDING PHOTOCOPY, RECORDING, OR ANY INFORMATION STORAGE AND RETRIEVAL SYSTEM, WITHOUT PERMISSION IN WRITING FROM THE PUBLISHER. ACADEMIC PRESS, INC. Ill Fifth Avenue, New York, New York 10003 United Kingdom Edition published by ACADEMIC PRESS, INC. (LONDON) LTD. 24/28 Oval Road, London NW1 Library of Congress Cataloging in Publication Data Main entry under title: Ecology of halophytes. 1. Halophytes. I. Reimold, Robert J., ed. II. Queen, William, ed. QK922.E24 581.5'265 72-88347 ISBN 0-12-586450-7 PRINTED IN THE UNITED STATES OF AMERICA CONTRIBUTORS Anderson, Charles Ε., Department of Botany, North Carolina State University, Raleigh, North Carolina 27607 Barbour, Michael G., Botany Department, University of California, Davis, California 95616 Caldwell, Marty η Μ., Department of Range Sciences, Utah State University, Logan, Utah 84321 Chapman, V. J., Department of Botany, Auckland University, Auckland, New Zealand Cotnoir, Leo J., Plant Science Department, College of Agriculture Science, University of Delaware, Newark, Delaware 19711 Daiber, Franklin C, College of Marine Studies and Department of Biological Sciences, University of Delaware, Newark, Delaware 19711 Davis, Donald E., Department of Botany and Microbiology, Auburn University Agricultural Experiment Station, Auburn, Alabama 36830 Duncan, Wilbur H., Department of Botany, University of Georgia, Athens, Georgia 30602 Edwards, Andrew C, Department of Botany and Microbiology, Auburn University Agricultural Experiment Station, Auburn, Alabama 36830 Gallagher, John L., The University of Georgia Marine Institute, Sapelo Island, Georgia 31327 Godfrey, Melinda M., Department of Botany/U.S. National Park Service, University of Massachusetts, Amherst, Massachusetts 01002 Godfrey, Paul J., Department of Botany/U.S. National Park Service, University of Massachusetts, Amherst, Massachusetts 01002 Kraeuter, John N., The University of Georgia Marine Institute, Sapelo Island, Georgia 31327 ix CONTRIBUTORS Macdonald, Keith Β., Department of Geological Sciences, University of California, Santa Barbara, Santa Barbara, California 93106 May, Mallory S., Ill, Biology Department, Brunswick Junior College, Brunswick, Georgia 31520 McMillan, Calvin, The Department of Botany and the Plant Ecology Research Laboratory, The University of Texas at Austin, Austin, Texas 78712 Mudie, Peta J., Foundation for Ocean Research, Scripps Institute of Oceano­ graphy, La Jolla, California 92037 Odum, Eugene P., Institute of Ecology, The University of Georgia, Athens, Georgia 30602 Queen, William H., Chesapeake Research Consortium, University of Maryland, College Park, Maryland 20742 Reimold, Robert J., The University of Georgia Marine Institute, Sapelo Island, Georgia 31327 Seneca, Ernest, D., Departments of Botany and Soil Science, North Carolina State University, Raleigh, North Carolina 27607 Shanholtzer, G. Frederick, The University of Georgia Marine Insitute, Sapelo Island, Georgia 31327 Teal, John M., Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543 Ungar, Irwin Α., Department of Botany, Ohio University, Athens, Ohio, 45701 Valiela, Ivan, Boston University Marine Program, Marine Biological Laboratory, Woods Hole, Massachusetts 02543 Walsh, Gerald E. Environmental Protection Agency, Gulf Breeze Laboratory, Sabine Island, Gulf Breeze, Florida 32561 Wolf, Paul L., Tyrone Biological Laboratory, Lebanon Valley College, Annville, Pennsylvania 17003 χ PREFACE This publication arose as a result of a symposium on the ecology of halo­ phytes sponsored by the Physiological Ecology section of the Ecological Society of America and held as a portion of the American Institute of Biological Sciences meetings, August 1972. The interest generated in preparing and presenting this symposium all pointed to the need for a review volume on the salt marsh ecosystem, the saline soil ecosystem, and what was known about these systems. The diversity of interests of the contributors demonstrates the comprehensive nature of the Ecology of Halophytes. The Ecology of Halophytes considers the fundamentals of distribution, anatomy, and physiology of halophytes. It also provides an overview of the role of the halophyte in ecosystems in various parts of the world. A section on habitat associations of halophytes considers the relation of the plants to other fauna and flora in natural systems. A final section deals with recent applied research related to halophytes and quantification of the impact of man on the ecology of halophytes. It is hoped that this publication will be of use for various disciplines working in saline wetlands ecosystems. It is intended to serve land use planners, federal and state natural resources and transportation interests, and real estate developers in providing a comprehensive summary of the "state of the art" in understanding halophytic ecosystems. With a better fundamental knowledge of the system, the above mentioned professionals should be better able to plan activities and uses compatible with the natural halophytic ecosystem and hope­ fully avoid some of the past errors man has made. We acknowledge the assistance of Charles R. Malone, program chairman for the Ecological Society of America, and F. John Vernberg, chairman of the Physiological Ecology Section of ESA, for arranging the symposium. Thanks also go to Winona B. Vernberg, Lee N. Miller, and James G. Gosselink for their assistance as symposium session chairman. We extend our sincere appreciation to the many scientists who have served as editorial reviewers for each chapter. In particular we recognize the valuable assistance of Rick A. Linthurst for his dedicated efforts of manuscript, proof and camera ready copy production. The untiring motivation from our families is also acknowledged. Robert J. Reimold William H. Queen xi FOREWORD Salt marshes are many things to many men. To those who live on the east coast they are the one remaining accessible bit of undisturbed wilderness. Unfortunately as unoccupied space they offer great opportunity to those who would destroy them by development. On the other hand, being the favored habitat of water fowl, substantial areas of marshland are being set aside as wild­ life reservations which require understanding of their ecology for their mainte­ nance. To the scientist salt marshes provide for study an ecological system with well-defined boundary conditions within which physical and biological factors interact. The physical environment is hostile to most of the organisms of the land, of the fresh water wetlands, and of the open sea. The result is a biota limited to the relatively few species of plants and animals adapted to periodic inundation and to life in waters of varied salinity. The salt marshes have been formed in sheltered places by waterborne sediments collected by those halophytes which can populate the intertidal zone. Of these Spartina alterniflora is the principal species throughout its range because it can survive longer periods of submergence than others and hence occupy the foreshore at lower tide levels. The marshes, as we know them today, have devel­ oped during a period of rising sea level. The peats formed each year have buried and often left undisturbed those formed in earlier years. A record is preserved in the depths of the peat deposits from which the history of the marsh may be reconstructed and which provides a chronology of the recent rise in sea level. Also preserved are artifacts which give evidence of man's occupation of marsh­ land areas and of his culture during earlier times. The interaction of tidal flow, the resulting sedimentation and erosion, and the physiology of the halophytes has produced a unique land form for the atten­ tion of the geomorphologist. The creeks which drain the marshes have an hydrol­ ogy which differs in important respects from terrestrial streams. The soil of the marshlands is distinctive in its saline character, its prevalent saturation with water, its high organic content, and its proverty in oxygen. In the study of salt marshes, the botanists have done a more thorough job than others. In the present volume they have continued to lead the way by the investigation of the halophytes and their ecology. The collection of papers pre- xiii FOREWORD sented should be useful to those with diverse interests as an account of what is being done currently toward understanding the ecology of the marshes. Alfred C. Redfield Woods Hole, Massachusetts xiv SALT MARSHES AND SALT DESERTS OF THE WORLD V. J. Chapman Department of Botany Auckland University Auckland, New Zealand Introduction In this contribution I do not intend to say anything about the physiology and morphology of salt marsh plants, nor anything about salt marsh soils and animals because these topics are covered in other articles in this volume. Since many of you are familiar with my book on salt marshes and salt deserts of the world, I will consider intensively only those areas in which additional information has come to hand since the book was written. In the past there has been considerable debate over what are halophytes. Generally, species capable of tolerating 0.5% or more NaCl are regarded as halophytes. Some evidence has been published in the past to indicate that some species, are obligate halophytes and reach their optimum growth at moderate to high salinities. Barbour (1970) has discussed this aspect in some detail and concluded that very few species are restricted above 0.5% NaCl. One characteristic of salt marshes and salt deserts is provided by the fact that only a relatively small number of plant species are capable of tolerating the degrees of salinity that occur. As a result, there are broad geographical areas in which there is a substantial uniformity in the vegetation. In some cases, subdivision can be based on temperatures or upon soil type. With this as background it seems to me that the major groups of maritime salt marshes and salt deserts (Fig. 1) are as follows: Maritime Marshes Arctic Group The Arctic Group is represented by the salt marshes of the Canadian and American Arctic, Greenland, Iceland, northernmost Scandinavia, and arctic Russia. The environment is extreme, especially in winter, and the marshes appear to be somewhat fragmentary as a result. Succession is very simple. The vegetation is dominated by the grass Puccinellia phryganodes, though species of Carex, especially C. subspathacea and C. maritima, play an important part at higher levels. Northern European Group This group includes marshes from the Iberian Peninsula northward around the English Channel, North Sea Coasts, and the Baltic Sea, as well as those on 3 s p m a w s e v o gr n a m d n a k) c a bl d oli s ( s ert s e d alt s s, e h s ar m alt- s of n o uti b stri did} 1. d he Fig.Worl(latc ECOLOGY OF HALOPHYTES the Atlantic coasts of Eire and Great Britain. Whilst there is a fundamental similarity in physiognomy and floristic composition, nevertheless, different communities can be recognized in specific areas. These sub-areas are related either to soil differences or, in the case of the Baltic, to salinity differences. Throughout the region there is a dominance of annual Salicornia species, Puccinellia maritima, Juncus gerardi, and the general salt marsh community. The North European Group can be divided into the following five subgroups: Scandinavian Subgroup — Scandinavian marshes are characterized by a high proportion of sand in the soil and have developed on a rising coastline where newly exposed shore sand can be blown inland. They are found in Scandinavia, Schleswig-Holstein, the west coast of Britain from the Severn to Northern Scotland, on the east coast of Eire, and from Kincardine to Inverness on the east coast of Scotland. These marshes are dominated by grasses, especially Puccinellia maritima, Festuca rubra, and Agrostis stolonifera, and for this reason are grazed by domestic animals. Grazing probably results in the elimination, or control, of dicotylodonous herbs such as Aster, Limonium, Triglochin, etc. Since the publication of Salt Marshes and Salt Deserts of the World a number of contributions have been made to the literature of the Scandinavian Subgroup. Foremost among these have been the papers by Dalby (1970), South Wales marshes; Gillner (1960), Swedish marshes; Gimingham (1964), East Scottish marshes; Packham and Liddle (1970), West Wales marshes; Round (1960), Dee marshes; and Taylor and Burrows (1968), Dee marshes. North Sea Subgroup — North Sea marshes have much more clay and silt in the soil and there tends to be a wider range of communities. Grasses are not so dominant and the general salt marsh community plays a greater role in the successions. These marshes are generally associated with a subsiding coastline, but their character is currently changing through the introduction or natural spread of Spartina townsendii or S. anglica. North Sea marshes are represented by the marshes of eastern England, southeast Scotland, northern Germany, and the low countries. Recent significant publications on the marshes of the North Sea Subgroup have been those by Köster (1961) and Beeftink (1965,1966). Baltic Subgroup — The Baltic Subgroup differs from the Scandinavian and North Sea Subgroups by the presence of some species, e.g. Carex paleacea, Juncus bufonius, and Desmoschoenus bottnica, that occupy dominant places in the succession. The brackish nature of the Baltic also permits Scirpus to be the primary colonist. English Channel Subgroup — Marshes in this subgroup were probably comparable with the North Sea Subgroup, but since the appearance of Spartina townsendii and S. anglica towards the end of the last century and their subsequent spread, these marshes physiognomically now look more like those of the U.S.A. In Poole Harbour, the origianl home of S. townsendii, aerial photography has been employed to see whether there have been any recent changes in the vegetation (Ran well et al. 1964, Bird and Ran well! 5