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AN ANALYSIS OF A SONORAN DESERT SPECIES DIVERSITY GRADIENT Item Type text; Dissertation-Reproduction (electronic) Authors Yensen, Arthur Eric, 1944- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 24/09/2021 16:14:26 Link to Item http://hdl.handle.net/10150/288134 INFORMATION TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. 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It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete. 4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced. 5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received. Xerox University Microfilms 300 North Zeeb Road Ann Arbor, Michigan 48106 I I 74-4184 YENSEN, Arthur Eric, 1944- AN ANALYSIS OF A SONORAN DESERT SPECIES DIVERSITY GRADIENT. The University of Arizona, Ph.D., 1973 Biology University Microfilms, A XEROXCompany , Ann Arbor, Michigan THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED. AN ANALYSIS OF A SONORAN DESERT SPECIES DIVERSITY GRADIENT by Arthur Eric Yensen A Dissertation Submitted to the Faculty of the DEPARTMENT OF BIOLOGICAL SCIENCES In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY WITH A MAJOR IN ZOOLOGY In the Graduate College THE UNIVERSITY OF ARIZONA 19 7 3 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE I hereby recommend that this dissertation prepared under my direction by Arthur Erio Yenaen entitled AN ANALYSIS OF A SONORAN DESERT SPECIES DIVERSITY GRADIENT be accepted as fulfilling the dissertation requirement of the degree of DOCTOR OF PHILOSOPHY lu • CLl.I% 'ait I (97 5 Dissertation Director Date After inspection of the final copy of the dissertation, the following members of the Final Examination Committee concur in its approval and recommend its acceptance: ^,tf 73 ~X CXjo. I If ?i> ^ J Q-U.rj I'f 7-? , C? t 1 % JCo~V\ C-AsSl v uXJL<-^ Qo y-, 7, V / /) 7 3 This approval and acceptance is contingent on the candidate's adequate performance and defense of this dissertation at the final oral examination. The inclusion of this sheet bound into the library copy of the dissertation is evidence of satisfactory performance at the final examination. STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the Uni­ versity Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allow­ able without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manu­ script in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED; ACKNOWLEDGMENTS This study was facilitated by help from several sources which I am happy to acknowledge here. I wish to thank the National Park Service for granting permission to set up a study site (site 4) inside the boundary of Saguaro National Monument. I also wish to thank Dr. E. L. Cockrura for the extended loan of the mammal traps, Mr. R. R. Snelling of the Los Angeles County .Museum for checking my ant identifications, and my brother, N. P. Yensen, for assisting in the field with some of the foliage height diversity measurements. Drs. S. M. Russell, H. R. Pulliam, C. H. Lowe, D. A. Thomson, C. T. Mason, and R. W. Hoshaw read and offered constructive criticism of this manuscript. I have especially appreciated their advice and encourage­ ment during the course of this study. I have profited from valuable discussion of species diversity with Dr. Pulliam and Dr. J. R. Hastings. My wife, Dana, assisted with various portions of the field work and offered excellent suggestions for improving the manuscript. iii TABLE OF CONTENTS Page LIST OF TABLES vi LIST OF ILLUSTRATIONS vii ABSTRACT ix INTRODUCTION 1 The Measurement of Diversity 2 Explanations of Diversity 21 THE STUDY AREA 27 The Tucson Mountains 27 The Study Sites 30 METHODS 33 THE DIVERSITY PATTERNS 40 DISCUSSION 69 SUMMARY AND CONCLUSIONS 80 APPENDIX Is FORMULAE OF SPECIES DIVERSITY INDICES AS USED BY THE ORIGINAL AUTHORS, SHOWING MODIFICATIONS MADE IN THIS PAPER IN THE INTEREST OF CONSISTENT USE OF SYMBOLS 83 APPENDIX II: RESULTS OF BIRD CENSUSES AT THE FIVE STUDY SITES BY MONTHS 86 APPENDIX III; RESULTS OF RODENT TRAPPING 95 APPENDIX IV; RESULTS OF LIZARD CENSUSES EXPRESSED AS INDIVIDUALS PER HECTARE 97 APPENDIX V: NUMBER OF ANT COLONIES (1.6 HA. TRANSECT) AT EACH SITE 98 iv V TABLE OF CONTENTS (Continued) Page APPENDIX VI; FOLIAGE ARTHROPOD SAMPLING RESULTS, SEPTEMBER 1972, BASED ON 1000 SWEEPS AT EACH SITE 100 APPENDIX VII: PERENNIAL PLANTS: NUMBER OF INDIVIDUALS FOUND ON TEN 0.1 HECTARE QUADRATS Ill APPENDIX VIII: LIFE FORMS OF PERENNIAL PLANT SPECIES USED IN CALCULATING PCD VALUES 113 APPENDIX IX: NUMBERS OF ANNUALS FROM 50 ONE- METER SQUARE QUADRATS AT EACH SITE 115 LITERATURE CITED 117 LIST OF TABLES Table Page 1. Effect of the evenness component on the value of the diversity index 13 2. Effect of the richness component on the value of the index 16 3. Effect of increasing numbers of individuals (N) and species (S) on the value of the index 17 4. Location of study sites 31 5. Number of individuals (number of pairs x 2) of breeding birds at the five study sites on the Tucson Mountains bajada, spring and summer, 1972 41 6. Seasonal changes in bird species diversity (H') values at the five study sites 47 7. Diversity values (H') of the major com­ munity components studied at the five study sites 50 8. Perennial plants: canopy cover as a percentage of one kilometer of line intercept at each site 57 9. Spring and summer annual plant numbers, species, and bioroass per 50 one-meter square quadrats at each site 60 10. Foliage height diversity (Hl) using various permutations of layers 62 11. Physiognomic cover diversity (PCD) values obtained using four and ten categories of growth forms and species cover diversity (SCD) values 62 vi LIST OF ILLUSTRATIONS Figure Page 1. Examples of species-area curves 5 2. Example of a species abundance curve 7 3. Comparison of H' and Dg 20 4. Map of study site 32 5. Vertebrate populations 43 6. Number of species at each site 44 7. Species diversity (H1) of breeding birds, rodents, ants, and foliage arthropods .... 45 8. Species diversity (H") of lizards, perennial plants, spring annuals, and summer annual plants .... 46 9. Seasonal variation in bird species diversity (H1) at the five study sites during 1972 48 10. Relationship between rodent and lizard diversity patterns and bur-sage CFranseria deltoidea) density 52 11. Arthropod populations 53 12. Plant populations 55 13. Perennial plant coverage 56 14. Regression of bird species diversity (BSD) on physiognomic cover diversity (PCD-four categories) 64 15. Regression of bird species diversity (BSD) on physiognomic cover diversity lPCD-10 categories) 65 vii viii LIST OF ILLUSTRATIONS (Continued) Figure Page 16. Regression of bird species diversity (BSD) on plant species cover diversity CSCD) 66 17. Regression of bird species richness on number of plant species 67 18. Regression of bird species diversity (H') on number of plant species 68 ABSTRACT Ten species diversity indices were discussed and compared using hypothetical and actual species abundance distributions. Only two indices, H' and D , consistently b increased with increases in richness and evenness. Since H' has been widely used, it was adopted in order to facili­ tate comparisons to other studies. H1 values for birds, rodents, lizards, ants, foliage arthropods, perennial plants, spring annual plants, and summer annual plants were determined at five study sites on a complex environmental gradient in the Tucson Mountains, Arizona.

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