STRUCTURE AND FUNCTION OF A CHIHUAHUAN DESERT ECOSYSTEM LONG-TERM ECOLOGICAL RESEARCH NETWORK SERIES LTER Publications Committee Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie Edited by Alan K. Knapp, John M. Briggs, David C. Hartnett, and Scott L. Collins Standard Soil Methods for Long-Term Ecological Research Edited by G. Philip Robertson, David C. Coleman, Caroline S. Bledsoe, and Phillip Sollins Structure and Function of an Alpine Ecosystem: Niwot Ridge, Colorado Edited by William D. Bowman and Timothy R. Seastedt Climate Variability and Ecosystem Response at Long-Term Ecological Sites Edited by David Greenland, Douglas G. Goodin, and Raymond C. Smith Biodiversity in Drylands: Toward a Unified Framework Edited by Moshe Shachak, James R. Gosz, Steward T.A. Pickett, and Avi Perevolotsky Long-Term Dynamics of Lakes in the Landscape: Long-Term Ecological Research on North Temperate Lakes Edited by John J. Magnuson, Timothy K. Kratz, and Barbara J. Benson Alaska’s Changing Boreal Forest Edited by F. Stuart Chapin III, Mark W. Oswood, Keith Van Cleve, Leslie A. Viereck and David L. Verbyla Structure and Function of a Chihuahuan Desert Ecosystem: The Jornada Basin Long-Term Ecological Research Site Edited by Kris M. Havstad, Laura F. Huenneke, and William H. Schlesinger STRUCTURE AND FUNCTION OF A CHIHUAHUAN DESERT ECOSYSTEM: THE JORNADA BASIN LONG-TERM ECOLOGICAL RESEARCH SITE Edited by Kris M. Havstad Laura F. Huenneke William H. Schlesinger 1 2006 1 Oxford University Press, Inc., publishes works that further Oxford University’s objective of excellence in research, scholarship, and education. Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi New Delhi Shanghai Taipei Toronto With offices in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore South Korea Switzerland Thailand Turkey Ukraine Vietnam Copyright ᭧ 2006 by Oxford University Press, Inc. Published by Oxford University Press, Inc. 198 Madison Avenue, New York, New York 10016 www.oup.com Oxford is a registered trademark of Oxford University Press 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, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Oxford University Press. Library of Congress Cataloging-in-Publication Data Structure and function of a Chihuahuan Desert ecosystem: the Jornada Basin long-term ecological research site / edited by Kris M. Havstad, Laura F. Huenneke, William H. Schlesinger. p. cm. Includes bibliographical references and index. ISBN-13 978-0-19-511776-9 ISBN 0-19-511776-X 1. Desert ecology—Chihuahuan Desert. 2. Jornada Experimental Range. I. Havstad, Kris M. II. Huenneke, L. F. III. Schlesinger, William H. QH107.S77 2006 557.54'0972'16—dc22 2005020889 987654321 Printed in the United States of America on acid-free paper We dedicate this volume to the hundreds of students and staff since 1912 who have worked so diligently and professionally in pursuit of science in and about this desert environment. Their efforts were and are the foundation of this synthesis and any clarity of thinking that results from reading the enclosed chapters. This page intentionally left blank Preface The Jornada Basin in southern New Mexico is truly a long-term research site, and this history is reflected in the databases described in many of the chapters in this book. Research in this basin formally began in 1912 with the creation by Presidential Order within the U.S. Department of Agriculture of the 77,000-ha Jornada Range Reserve. Just months after New Mexico was granted statehood, these lands were withdrawn from the public domain due to the efforts of Elmer Otis Wooton, a professor at the New Mexico College of Agriculture and Me- chanical Arts, and Charles T. Turney, a prominent rancher and farmer in the Las Cruces area. Wooton’s published assessments of rangeland conditions throughout the Southwest at the turn of the twentieth century painted a bleak picture of resource deterioration due to a combination of drought and mismanagement. As a consequence of this assessment, he proposed creation of the Jornada Range Reserve (later named the Jornada Experimental Range) to determine proper man- agement practices through research, then demonstrate those practices to stock producers in the region. By 1915, under the direction of scientists with the U.S. Forest Service, long-term research objectives were established and implemented with C. T. Turney as the cooperating rancher who stocked the reserve. Early publications, primarily USDA bulletins or journal articles in Ecology and the Botanical Gazette, appeared in print beginning in 1917. Researchers such as C. L. Forsling, J. T. Jardine, R. S. Campbell, and R. H. Canfield authored many of these early works, which are both classics in rangeland management and part of the foundation of our LTER studies decades later. The creation in 1927 of the Chi- huahuan Desert Rangeland Research Center (CDRRC; initially known as the Col- lege Ranch) under the jurisdiction of New Mexico State University on 24,000 ha vii viii Preface adjacent to the Jornada Range established the 101,000-ha area for long-term re- search in the basin that operates today. The research during the early twentieth century had numerous themes. Much of the emphasis was on management related to agricultural production. Many of the principles that have been developed about livestock grazing management and rangeland improvement practices in the Southwestern United States and for arid lands in general can be traced to studies in the Jornada Basin. Yet during these earlier decades there were also classic papers published on vegetation dynamics, resource redistribution, and small-mammal ecology. Over 40 years ago the first interdisciplinary studies were initiated; these studies served as a forerunner for the collaborative studies of the International Biological Programme (IBP) of the 1970s. They also prompted the involvement of USDA scientists with the Agri- cultural Research Service which assumed control of the Jornada Experimental Range in 1954. Intensive studies of grassland and shrubland sites within the Jor- nada Basin formed important elements in the comparative IBP investigations of ecosystem productivity and processes. Those IBP projects set the stage for the next phase of the research program. The establishment of a National Science Foundation Long-Term Ecological Re- search (LTER) site in the Jornada Basin of south-central New Mexico in 1981, as part of the original cohort of LTER sites, followed this long record of scientific in- vestigation of ecosystem processes and management. The LTER program catalyzed and coalesced efforts of scientists across a multitude of disciplines and affiliations, and facilitated the understanding of Chihuahuan desert ecosystems synthesized in this volume. Much of that research effort, evident in the chapters of this book, has been creating an abiotic-based understanding of this ecosystem given the over- whelming importance of these bottom-up processes in the Jornada Basin. That un- derstanding has now matured into a more complex set of studies on biotic and abi- otic interactions across multiple spatial and temporal scales. The chapters of this book reflect this long history of research, report on many of the key intensive stud- ies that have characterized this program for decades, but also include the more in- tegrative, across-scale investigations that have developed in recent years. The vision for our research program in the twenty-first century is easily de- scribed—innovative, carefully executed, and insightful research relevant to the public in the problems being addressed, effective in providing solutions to those problems, collaborative across disciplines, global in its application to arid lands, and ethical in its conduct and its explanation. Although socioeconomic studies have not been the explicit focus of our programs, increasingly we see our studies expanding to include comparisons of human impact in the cross-border region of the United States and Mexico. Within this region, it is increasingly important that we develop the knowledge and technologies for mitigating the impacts to desert environments and for improving environmental conditions for the increasing hu- man population that lives here. An understanding of basic processes of desert ecosystems must form the basis of management and remediation techniques. Pre- dicting how arid land ecosystems here and elsewhere around the globe will re- spond to human impacts, and ameliorating these impacts are critical goals for our future research. Preface ix Our progress is built on the efforts of numerous scientists, students, technical staff, and collaborators that have been involved over the past 100 years. Several deserve mention and our thanks because of their length of service working in this desert and the importance of their contributions to our understanding of this sys- tem today. Robert Gibbens, Fred Ares, Carlton Herbel, Rex Pieper, Reldon Beck, Gary Donart, Gary Cunningham, John Ludwig, John Tromble, and Walt Whitford are a few of these names. We are fortunate that some of these people are still working with us in retirement today and have made significant contributions to this synthesis. The cover photograph presents several important elements of this desert en- vironment intended