Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2012 Soil moisture dynamics in agriculturally-dominated landscapes after the introduction of native prairie vegetation Jose Antonio Gutierrez Lopez Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Plant Sciences Commons, and the Soil Science Commons Recommended Citation Gutierrez Lopez, Jose Antonio, "Soil moisture dynamics in agriculturally-dominated landscapes after the introduction of native prairie vegetation" (2012). Graduate Theses and Dissertations. 12337. https://lib.dr.iastate.edu/etd/12337 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Soil moisture dynamics in agriculturally-dominated landscapes after the 1 introduction of native prairie vegetation 2 3 By: 4 José Antonio Gutiérrez López 5 6 A thesis submitted to the graduate faculty 7 In partial fulfillment of the requirements for the degree of: 8 9 MASTER OF SCIENCE 10 11 Major: Sustainable Agriculture 12 13 Program of Study Committee: 14 15 Thomas Isenhart 16 Matthew Helmers 17 Heidi Asbjornsen 18 Alan D. Wanamaker 19 20 Iowa State University 21 Ames, Iowa 22 2012 23 24 Copyright © José Antonio Gutiérrez López, 2012. All rights reserved. 25 ii 26 27 28 29 30 Dedication 31 32 33 34 35 A ti, Agustina 36 A mis padres 37 Gloria y René 38 A mis hermanos 39 Patricia y René 40 A todos mis amigos 41 42 43 44 45 46 47 48 iii Table of contents 49 List of Figures .......................................................................................................................... viii! 50 List of Tables................................................................................................................................x! 51 CHAPTER I....................................................................................................................1! 52 GENERAL INTRODUCTION....................................................................................................1! 53 1.1 Contributions of this thesis to the overall mission of the Neal Smith National Wildlife 54 Refuge ..........................................................................................................................................1! 55 1.2 Introduction ............................................................................................................................2! 56 1.3 Thesis organization ................................................................................................................5! 57 1.4 Literature review ....................................................................................................................5! 58 1.4.1 History of native ecosystems in the Midwest .................................................................5! 59 1.4.2 Soil moisture and its role in the ecosystem.....................................................................6! 60 1.4.3 Factors influencing soil moisture....................................................................................8! 61 1.4.3.1 Effects of land cover on soil moisture dynamics.........................................................8! 62 1.4.3.2 Effects of topographic position....................................................................................9! 63 1.4.3.3 Effects of precipitation...............................................................................................10! 64 1.4.3.4 Water uptake by plants...............................................................................................10! 65 1.4.4 Study of plant water uptake using stable isotopes ........................................................11! 66 1.4.5 Importance of the study of soil moisture dynamics......................................................13! 67 1.5 Objectives.............................................................................................................................14! 68 1.6 Hypotheses ...........................................................................................................................15! 69 1.7 Study site and description of the experimental setup...........................................................18! 70 1.7.1 Study Site......................................................................................................................18! 71 1.7.2 Experimental design......................................................................................................19! 72 iv 1.8 Description of the overall methodology...............................................................................21! 73 1.9 References ............................................................................................................................24! 74 CHAPTER II................................................................................................................30! 75 ANALYSIS OF SOIL MOISTURE DYNAMICS UNDER MIXED ANNUAL-PERENNIAL 76 ECOSYSTEMS..........................................................................................................................30! 77 1 Introduction .............................................................................................................................30! 78 2 Materials and Methods............................................................................................................33! 79 2.1 Study area.........................................................................................................................33! 80 2.2 Experimental design.........................................................................................................34! 81 2.3 Data collection and processing ........................................................................................35! 82 2.3.1 Conversion of dielectric constant to volumetric water content ....................................35! 83 2.3.2 Soil bulk density ...........................................................................................................36! 84 2.3.3 Calibration of soil moisture readings............................................................................37! 85 2.4 Statistical analysis............................................................................................................38! 86 3 Results.....................................................................................................................................39! 87 3.1 Precipitation .....................................................................................................................39! 88 3.2 Soil bulk density ..............................................................................................................39! 89 3.3 Volumetric water content by depth..................................................................................40! 90 3.4 Average soil water storage in the upper 60 cm................................................................40! 91 3.4.1 Soil water storage by depth increments ........................................................................41! 92 3.5 Effects of land cover on soil water storage......................................................................42! 93 3.6 Effects of topographic position on soil water storage......................................................44! 94 3.7 Other factors influencing soil moisture............................................................................45! 95 4 Discussion ...............................................................................................................................47! 96 v 4.1 Variations under land cover.............................................................................................47! 97 4.2 Variations under topographic position.............................................................................52! 98 4.3 Limitations to this study...................................................................................................55! 99 5 Conclusions.............................................................................................................................56! 100 6 References ...............................................................................................................................59! 101 7 Figures.....................................................................................................................................66! 102 8 Tables ......................................................................................................................................76! 103 CHAPTER III ..............................................................................................................87! 104 ASSESSING WATERFLOW AND UPTAKE DEPTH PATTERNS UNDER MIXED 105 ANNUAL-PERENNIAL ECOSYSTEMS USING STABLE OXYGEN (18O) AND 106 HYDROGEN (2H) ISOTOPES..................................................................................................87! 107 1 Introduction .............................................................................................................................87! 108 2 Study design and methods.......................................................................................................93!