Weed Ecology in Natural and Agricultural Systems Weed Ecology in Natural and Agricultural Systems Barbara D. Booth Department of Plant Agriculture University of Guelph Canada Stephen D. Murphy Department of Environment and Resource Studies University of Waterloo Canada and Clarence J. Swanton Department of Plant Agriculture University of Guelph Canada CABI Publishing CABI Publishing is a division of CAB International CABI Publishing CABI Publishing CAB International 44 Brattle Street Wallingford 4th Floor Oxon OX10 8DE Cambridge, MA 02138 UK USA Tel: +44 (0)1491 832111 Tel: +1 617 395 4056 Fax: +44 (0)1491 833508 Fax: +1 617 354 6875 E-mail: [email protected] E-mail: [email protected] Web site: www.cabi-publishing.org ©CAB International 2003. All rights reserved. No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording or otherwise, without the prior permission of the copyright owners. A catalogue record for this book is available from the British Library, London, UK. Library of Congress Cataloging-in-Publication Data Booth, Barbara D. Weed ecology in natural and agricultural systems/Barbara D. Booth, Stephen D. Murphy, and Clarence J. Swanton. p. cm. Includes bibliographical references (p. ). ISBN 0-85199-528-4 (alk. paper) 1. Weeds—Ecology. 2. Weeds. I. Murphy, Stephen D. II. Swanton, Clarence J. III. Title. SB611.B59 2003 632’.5—dc21 2002010884 ISBN 0 85199 528 4 Typeset by Wyvern 21 Ltd, Bristol Printed and bound in the UK by Biddles Ltd, Guildford and King’s Lynn Contents Preface vii 1. Ecology of Weeds 1 Part I. Population Ecology 15 2. Describing the Distribution and Abundance of Populations 17 3. The Structure and Dynamics of Populations 29 4. Sexual Reproduction 49 5. Asexual Reproduction 63 6. From Seed to Seedling 81 7. Growing Up, Getting Old and Dying 101 Part II. Interactions Between Populations 117 8. Interactions Between Populations I: Competition and Allelopathy 119 9. Interactions Between Populations II: Herbivory, Parasitism and Mutualisms 139 10. Studying Populations and Their Interactions 155 Part III. Community Ecology 179 11. Basic Community Concepts and Diversity 181 12. Community Dynamics: Succession and Assembly 207 13. Plant Invasions 235 14. Studying Community Structure and Dynamics 255 Part IV. Conclusions 275 15. The Importance of Weed Ecology to Management 277 Part V. Appendix 285 Glossary 287 Subject Index 293 Species Index 299 v Preface Our goal in writing this book was to describe addressed, as an overview of what is to why weeds occur where they do. We have come, and to assist the reader when review- made no attempt to discuss their manage- ing the material. At the end of each chapter ment and control: there are excellent texts there is a list of questions, the first of which available for that. Rather, we think that stu- refers to a weed of your (the student’s) dents should understand how and why choice. It can be a common widespread weeds fit into their environment. This text weed, or it may be a local problem. You will presents ecological principles as they relate be asked to summarize information that is to weeds. Ecology is central to our under- known about your weed in relation to the standing of how and why weeds invade and material discussed in each chapter. There yet there are few books that make this con- may be a lot or very little information avail- nection. That is the niche we hope to fill. able to you. The idea behind this is to apply We make no excuses for using the word the ecological principles you learn in the ‘weed’, and, since humans decide what chapter to a weed of interest, and to give you species are considered to be a weed, we practice in researching a topic. Our hope is make no attempt at a detailed definition. We that by the end of the book, you will have could really have used the word ‘plant’ created a ‘case history’ of your chosen weed. throughout the text. We have tried to present For the instructor, we designed this a broad array of weed examples, and have book so that the material could be covered in therefore selected weed examples from dif- a single-term course by covering approxi- ferent types of systems – agricultural, man- mately one ‘content chapter’ per week. aged (e.g. forestry) and natural systems – and Chapters 1 and 15 are a brief introduction from around the world. and conclusion. Two chapters (10 and 14) The book was designed as a teaching discuss how ecology ‘is done’, i.e. method- text for a middle year undergraduate course. ology, experimental design and basic calcu- No ecological background is assumed, lations. These can be used as you see fit. We although some basic biology is required. We have tried to keep the writing precise and have tried to write it and arrange the materi- concise and to include only pertinent infor- al so that it is presented in a clear concise mation. If we have done our job well, stu- manner. At the beginning of each chapter, dents should be able to read and understand we have listed concepts that will be all of the information. vii viii Preface We have used common names through- Lonsbary read sections or chapters. Of out the text with Latin names given the first course we accept the responsibility for any time the species is mentioned in each chap- errors that occur. We also thank the authors ter. We did this because common names are and publishers who allowed us to use their easier to remember when first learning about illustrations and Tim Hardwick of CAB a species. A species list of common and International who kept us on in spite of Latin names is provided at the end of the many missed deadlines. book. Finally, we thank our spouses, David We thank many people who assisted in Beattie, Tara Murphy and Josee Lapierre, the writing and production of this book. who probably heard more about ‘the book’ David Clements and Jason Cathcart provided than they wanted, but kept smiling and nod- detailed comments on many versions of the ding their heads anyway. We dedicate this text. Cheryl Corbett, Sara Mohr and Sheryl book to them. 1 Ecology of Weeds Concepts • The terms ‘weed’, ‘invader’, ‘colonist’, ‘exotic’, ‘non-native’ and others are often used in overlapping and conflicting manners. • Weeds are classified based on their impact on human activities. Therefore, the effect of a weed is difficult to quantify because it depends on our personal biases. • Definitions and classifications in ecology are often arbitrary and made for purely prac- tical reasons. They do not necessarily reflect any innate structure of nature. • Ecology can be studied at a variety of levels. In this book, we focus on population and community ecology. • Weed ecology provides a basic understanding of the distribution and abundance of weeds in natural and managed systems. In the long term, it may change our attitudes and perceptions towards weeds and alter the way we manage them. Introduction what we are about to say, and you may not be tested on it, but it will put what you are It may be tempting for you to start this book about to learn into context. with Chapter 2. After all, the real informa- There are a number of excellent weed tion doesn’t start until then, and exam ques- science (Radosevich et al., 1997; Zimdahl, tions rarely focus on what you learn in 1999a) and plant ecology (Crawley, 1997a; Chapter 1. However, Chapter 1 is important Barbour et al., 1999) texts. We have found, because it sets the tone for what is to follow. however, that very few texts are devoted A Shakespearean play or an opera always entirely to the basic ecology of weeds. A begins with a prologue. If you walk in after number of books are available on plant inva- the prologue has finished, you will certain- sions; however, they often: (i) assume an in- ly follow the plot and enjoy the play, but you depth understanding of ecological princi- might not understand the ‘why’ of the char- ples; (ii) focus heavily on the control and acters’ actions. Consider this chapter to be a management of invasive species; or (iii) pro- prologue. You may already know much of vide a detailed description of the biology of © 2003 CAB International. Weed Ecology in Natural and Agricultural Systems 1 (B.D. Booth, S.D. Murphy and C.J. Swanton) 2 Chapter 1 (a) Plants Animals Abiotic environment (b) Plants Animals cutting hunting trampling Abiotic pollution changing land use pollution environment changing water level changing air and water quality changing land use patterns (c) Crop Weed Animals tillage herbicides tillage Abiotic pesticides environment tillage herbicides pesticides Fig. 1.1. Schematic diagram of three community types: (a) natural community with no human disturbance, (b) natural community with human disturbance and (c) agricultural system. Ecology of Weeds 3 individual weedy species without providing construction, tillage) (Fig. 1.1). The human a broad background. Our goal is to provide activities that influence natural or managed you with a link between the fields of weed systems are ultimately biological in nature. science, plant invasions and ecology. This In the three main sections of this chap- book will give you a basic ecological under- ter we introduce you to weeds, to ecology standing of how plants invade natural, dis- and finally to weed ecology. In Part I, we turbed and agricultural ecosystems. present the muddled vocabulary used to This book was not designed to replace a describe, define and characterize weeds.