precipitation effects on soil carbon cycling in the sonoran desert

PRECIPITATION EFFECTS ON SOIL CARBON CYCLING IN THE SONORAN DESERT by Jessica Marie Cable ___________ A Dissertation Submitted to the Faculty of the DEPARTMENT OF ECOLOGY AND EVOLUTIONARY BIOLOGY In Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2006 UMI Number: 3208062 3208062 2006 UMI Microform Copyright All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, MI 48106-1346 by ProQuest Information and Learning Company. 2 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Dissertation Committee, we certify that we have read the dissertation prepared by Jessica Marie Cable entitled “Precipitation Effects on Soil Carbon Cycling in the Sonoran Desert” and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy. _______________________________________________________________________ Date: 4-7-2006 Travis E. Huxman _______________________________________________________________________ Date: 4-7-2006 Brian J. Enquist _______________________________________________________________________ Date: 4-7-2006 Robert Robichaux _______________________________________________________________________ Date: 4-7-2006 Alfredo Huete _______________________________________________________________________ Date: 4-7-2006 Russell L. Scott Final approval and acceptance of this dissertation is contingent upon the candidate’s submission of the final copies of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. ________________________________________________ Date: 4-7-2006_____ Dissertation Director: Travis E. Huxman 3 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 University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgement of source is made. Requests for permission for extended quotation from or reproductions of this manuscript in whole or in part may be granted by the copyright holder. Signed: Jessica M. Cable 4 ACKNOWLEDGEMENTS I am grateful to the following people that supported my research and professional development: my husband, Bill Cable; my parents, Jane Young and Dr. David T. Young; my faithful hound, Pete; members of my dissertation committee, collaborators, and peers; Dr. Kiona Ogle, Dr. David Williams, Dr. David Tissue, Dr. Scott Saleska, Joost Van Heran, Enrico Yepez-Gonzalez, and Dr. Keirith Snyder. The following organizations and institutions provided material and financial support during my doctoral research: The Institute for the Study of Planet Earth; The University of Arizona Department of Ecology and Evolutionary Biology; the United States Department of Agriculture – Agricultural Research Center; SAHRA (Sustainability of semi-Arid Hydrology and Riparian Areas); NCEAS - PrecipNet (National Center for Ecological Analysis and Synthesis); CATTS, NSF GK-12 science outreach fellowship; BASIN (Biosphere-Atmosphere Stable Isotope Network); International Arid Lands Consortium; and NSF Division of Environmental Biology. 5 DEDICATION I am grateful to my husband Bill, who through late nights, warm meals, and unmatched technical expertise, has supported and encouraged me. I could not have done this without you, and I would split this PhD with you if it were permitted. 6 TABLE OF CONTENTS LIST OF FIGURES……………………………………………………………………….9 LIST OF TABLES……………………………………………………………………….11 ABSTRACT…………………………………………………………………………… 12 INTRODUCTION……………………………………………………………………….14 PRESENT STUDY………………………………………………………………………21 REFERENCES………………………………………………………………………… 33 APPENDIX A: PRECIPITATION PULSE SIZE EFFECTS ON SONORAN DESERT SOIL MICROBIAL CRUSTS………………………………………………………… 43 Abstract……………………………………………………………………………… 44 Introduction……………………………………………………………………………45 Materials and methods ……………………………………………………………… 48 Results…………………………………………………………………………………57 Discussion…………………………………………………………………………… 59 Acknowledgements……………………………………………………………………63 References…………………………………………………… …………………… .64 Figure legends…………………………………………………………………………71 Figures……………………………………………………………………………… 73 APPENDIX B: SOIL RESPIRATION RESPONSE TO PRECIPITATION: THE EFFECTS OF GRASS AND SOIL SURFACE ON SOIL MOISTURE……………… 78 Abstract……………………………………………………………………………… 79 7 TABLE OF CONTENTS - continued Introduction……………………………………………………………………… ….80 Methods……………………………………………………………………………… 84 Results…………………………………………………………………………… ….88 Discussion…………………………………………………………………………… 93 Acknowledgements…………………………………………………………… ……102 Literature cited……………………………………………………………………….103 Tables……………………………………………………………………………… 114 Figure legends……………………………………………………………………… 116 Figures…………………………………………………………………………… …119 APPENDIX C: EFFECTS OF PRECIPITATION PULSE SEQUENCING ON PLANT AND SOIL RESPONSE TO PRECIPITATION PULSE SIZE IN THE SONORAN DESERT……………………………………………………………………………… 125 Abstract………………………………………………………………………….… 126 Introduction………………………………………………………………………… 127 Methods………………………………………………………………………… … 130 Results……………………………………………………………………….……….133 Discussion………………………………………………………………… ……… 137 Acknowledgements………………………………………………………………… 143 Literature cited……………………………………………………………………….144 Figure legends……………………………………………………………………… 153 Figures…………………………………………………………………… …………156 8 TABLE OF CONTENTS - continued APPENDIX D: PRECIPITATION EFFECTS ON SOIL RESPIRATOIN IN SEMI-ARID ECOSYSTEMS: THE ROLE OF WOODY PLANT ENCROACHMENT………………………………………………………………… 164 Abstract………………………………………………………………………………165 Introduction……………………………………………………………………….….166 Methods………………………………………………………………………………169 Results…………………………………………………….………………………….172 Discussion……………………………………………………………… ………… 175 Acknowledgements…………………………………………………… ……………179 Literature cited……………………………………………………………………….180 Tables…………………………………………………………………………… …188 Figure legends……………………………………………………………………… 189 Figures……………………………………………………………………………….191 APPENDIX E: PERMISSION FROM JOURNAL… ……………………………… 195 Journal cover page……… ………………………………………………………….197 9 LIST OF FIGURES APPENDIX A: PRECIPITATION PULSE SIZE EFFECTS ON SONORAN DESERT SOIL MICROBIAL CRUSTS FIGURE 1, Crust CO 2 flux response to water application……………………………73 FIGURE 2, Keeling plot intercepts for different watering treatments…….……… 74 FIGURE 3, Carbon pool isotope values………………………………………………75 FIGURE 4, Percent carbon contributed to CO 2 flux from crust and soil…………… 76 FIGURE 5, Precipitation size distribution across 3 deserts………………………… 77 APPENDIX B: SOIL RESPIRATION RESPONSE TO PRECIPITATION: THE EFFECTS OF GRASS AND SOIL SURFACE ON SOIL MOISTURE FIGURE 1, Effects of a large pulse after prolonged drought on respiration, soil moisture, and soil temperature……………………………………………………119 FIGURE 2, Effects of pulse size and initial soil moisture on respiration, soil temperature, soil moisture, and soil temperature and moisture effects on respiration…………………………………………………………………………120 FIGURE 3, Effects of pulse history and a large pulse after prolonged drought on respiration, soil moisture, and soil temperature………………………………… 121 FIGURE 4, Effects of pulse size, initial soil moisture, and pulse history on respiration, soil temperature, soil moisture, and soil temperature and moisture effects on respiration…………………………………………………………………………122 FIGURE 5, Relationship between initial respiration rate and respiration responsiveness to rainfall………………………………………………………………………….123 [...]... changes in precipitation for arid and semiarid regions EFFECTS OF PRECIPITATION PULSE SEQUENCING ON PLANT AND SOIL CO2 RESPONSE TO PULSE SIZE IN THE SONORAN DESERT (The methods, results, and conclusions of this study are presented in the paper appended to this dissertation in Appendix C The following is a summary of the most important findings in this document This paper is in preparation for submission... changes in activity How soil activity is driven by changes in water content associated with individual pulses is poorly understood The effects of precipitation on soil processes likely depend on ecosystem structure, which influences the soil environment The goal of this dissertation was to determine how soil carbon cycling responds to precipitation in the context of ecosystem structure (plant composition,... dissertation The following is a description and summary of the most important findings in these documents PRECIPITATION PULSE SIZE EFFECTS ON SONORAN DESERT SOIL MICROBIAL CRUSTS (This work has been published: Cable JM and Huxman TE (2004) Precipitation pulse size effects on Sonoran Desert soil microbial crusts Oecologia 141(2): 317-324; and has been included in this dissertation in Appendix A with kind... functional type was size dependent with differences occurring only with large shrubs This work suggests that large scale simulations of soil carbon cycling in deserts should carefully consider wet-dry transitions in the context of plant functional type and initial soil condition in order to predict the responses to global change 14 INTRODUCTION Water limited regions and precipitation patterns Rising... contents during this period cause soil to rapidly dry between storms, resulting in elevated soil moisture only in the immediate days following a rain event, limiting the access of organisms to resources that may be available in the soil or maintaining them in periods of dormancy (Noy-Meir 1973, Weltzin et al 2003, Huxman et al 2004b) Pulses of precipitation vary in magnitude and timing, altering the. .. ecosystems, the size of the rainfall events appear to be important in determining which components are active and to what degree Soil respiration, that is respiration from soil microbes, roots, and crusts if present, represents one of the largest components of the local carbon cycle contributing to the global carbon budget (Rustad et al 2000) Soil moisture is a controller of soil respiration so a change in. .. TABLES APPENDIX C: EFFECTS OF PRECIPITATION PULSE SEQUENCING ON PLANT AND SOIL RESPONSE TO PRECIPITATION PULSE SIZE IN THE SONORAN DESERT TABLE 1, Statistical analyses of Experiments in June 2002 and 2003…………… 114 TABLE 2, Statistical analyses of Experiments in August 2002 and 2003…… … 115 APPENDIX B: SOIL RESPIRATION RESPONSE TO PRECIPITATION: THE EFFECTS OF GRASS AND SOIL SURFACE ON SOIL MOISTURE TABLE... contribution of different ecosystem components to ecosystem carbon cycling is pulse size dependent due to the different locations of these components into the soil profile The majority of rainfall events in the Sonoran, Chihuahuan, and Mojave Deserts are small pulse events ( . Marie Cable entitled Precipitation Effects on Soil Carbon Cycling in the Sonoran Desert and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor. decomposition, nitrogen mineralization / immobilization and soil carbon cycling. These effects on ecosystem processes occur in addition to the direct effects plants have on ecosystem processes by their. transitions in the context of plant functional type and initial soil condition in order to predict the responses to global change. 14 INTRODUCTION Water limited regions and precipitation