UNLV Retrospective Theses & Dissertations 1-1-1995 A gradient analysis of Coleogyne communities in Southern Nevada Simon Adams Lei University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/rtds Repository Citation Lei, Simon Adams, "A gradient analysis of Coleogyne communities in Southern Nevada" (1995). UNLV Retrospective Theses & Dissertations. 464. http://dx.doi.org/10.25669/1anj-1473 This Thesis is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. 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Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. A Bell & Howell Information Company 300 North Zeeb Road. Ann Arbor. Ml 48106-1346 USA 313/761-4700 800/521-0600 A GRADIENT ANALYSIS OF COLEOGYNE COMMUNITIES IN SOUTHERN NEVADA by Simon A. Lei A thesis submitted in partial fulfillment of the requirements for the degree of Masters of Science in Biological Sciences Department of Biological Sciences University of Nevada, Las vegas May 1995 UMI Number: 1374893 OMI Microform 1374893 Copyright 1995, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 The thesis of Simon A. Lei for the degree of Masters of Science in Biological Sciences is approved. Chairperson, Lawrence R. Walker, Ph.D. Examining Committee Member, Wesley E. Niles, Ph.D. Examining Committee Member, Stanley D. Smith, Ph.D Graduate Faculty Representative, Rodney V. Metcalf, Ph.D. Interim Dean of Graduate College, Cheryl Bowles, Ed.D. University of Nevada, Las Vegas May 1995 ABSTRACT Species richness, density, and abundance in Coleoqvne ramosissima (blackbrush) shrublands were compared on 15 elevational transects in the Spring and Sheep Mountain Ranges adjacent to the Las Vegas Valley. Coleoqvne shrublands shared relatively broad upper and lower ecotones with Pinus-Juniperus and Larrea-Ambrosia vegetation, respectively. Lower Coleoqvne ecotones generally had the highest species richness, and Pinus-Juniperus woodlands had the lowest species richness. Detrended correspondence analysis (DECORANA) suggested that elevation and soil depth were significantly associated with the distribution of stand and species groups identified from two-way indicator species analysis (TWINSPAN) in the Spring and Sheep Mountians Ranges. Precipitation and soil moisture were positively correlated with elevation; air and soil temperatures were negatively correlated with elevation. Coleoqvne density was positively correlated with soil moisture, soil organic matter, Coleoqvne water potential, Coleoqvne leaf biomass, and Coleoqvne stem and leaf phosphorus. Soil moisture and soil organic matter appeared to influence the distribution of Coleoqvne at its lower elevational boundary in southern Nevada. iii TABLE OP CONTENTS ABSTRACT .............................................. iii LIST OF TABLES......................................... V LIST OF FIGURES....................................... vi ACKNOWLEDGEMENTS ..................................... viii INTRODUCTION ........................................... 1 CHAPTER 1 COMPOSITION AND DISTRIBUTION OF COLEOGYNE COMMUNITIES IN SOUTHERN NEVADA .................... 4 Abstract ..................................... 4 Introduction........ 5 Methods ...................................... 6 Results and Discussion ....................... 9 Conclusions .................................. 14 CHAPTER 2 CLASSIFICATION AND ORDINATION OF COLEOGYNE COMMUNITIES IN SOUTHERN NEVADA ..................... 15 Abstract ..................................... 15 Introduction ................................. 16 Methods ...................................... 19 Results ...................................... 22 Discussion ................................... 33 CHAPTER 3 BIOTIC AND ABIOTIC FACTORS INFLUENCING THE DISTRIBUTION OF COLEOGYNE COMMUNITIES IN SOUTHERN NEVADA ............................................. 42 Abstract ..................................... 42 Introduction ................................. 4 3 Methods ...................................... 47 Results ...................................... 49 Discussion ................................... 69 CONCLUSIONS ............................................ 78 APPENDIX 1 PERCENT COVER OF WOODY TAXA IN THE SPRING AND SHEEP MOUNTAIN RANGES ......................... 82 APPENDIX 2 PLOT NUMBERS AND RANGES OF PLOT ELEVATIONS IN THE SPRING AND SHEEP MOUNTAIN RANGES ........... 92 APPENDIX 3 NAMES AND ABBREVIATIONS OF WOODY TAXA IN SOUTHERN NEVADA .................................... 9 3 APPENDIX 4 PERCENT COVER OF WOODY TAXA IN LUCKY iv STRIKE CANYON 97 APPENDIX 5 NAMES AND ABBREVIATIONS OF WOODY TAXA IN LUCKY STRIKE CANYON ............................... 100 APPENDIX 6 SOIL MOISTURE AND SOIL ORGANIC MATTER AT DEPTHS OF 0-7 AND 7-15 CM IN LUCKY STRIKE CANYON ............................................ 102 APPENDIX 7 COLEOGYNE WATER POTENTIAL AND SOIL COMPACTION IN LUCKY STRIKE CANYON ................. 107 APPENDIX 8 SOIL TEMPERATURE AT THE SURFACE AND AT DEPTHS OF 5, 10, AND 15 CM IN OPEN SPACES AND UNDER SHRUB CANOPIES IN LUCKY STRIKE CANYON .............. 108 BIBLIOGRAPHY .......................................... 115 v LIST OF TABLES Table 1 Four major species groups identified by TWINSPAN in the Spring and Sheep Mountain Ranges .............. 23 Table 2 Four major species groups identified by TWINSPAN along the lower Coleogyne ecotone in Lucky Strike Canyon .............................................. 25 Table 3 Correlations of physical factors with the stand ordination scores of DECORANA from the Spring and Sheep Mountain Ranges ............................... 28 Table 4 Correlations of physical factors with the stand ordination scores of DECORANA from the lower Coleoqvne ecotone at Lucky Strike Canyon ............ 3 0 Table 5 Correlations of Coleoqvne density with various abiotic factors along the lower ecotone at Lucky Strike Canyon ....................................... 59 Table 6 Correlations of Coleoqvne density with various biotic factors along the lower ecotone at Lucky Strike Canyon ....................................... 66 vi LIST OF FIGURES FIGURE 1 Distribution of fifteen elevational transects among four geographical areas in southern Nevada ... 7 FIGURE 2 Species richness among 15 transects in five vegetation zones in the Spring and Sheep Mountain Ranges .............................................. 10 FIGURE 3 Density of dominant species in 15 transects within five vegetation zones ...................... 11 FIGURE 4 Rank-abundance curves of woody plants in five vegetation zones ................................... 13 FIGURE 5 Stand ordination scores generated by DECORANA from the Spring and Sheep Mountain Ranges ........ 26 FIGURE 6 Stand ordination of DECORANA from the lower Coleoqvne ecotone at Lucky Strike Canyon ......... 29 FIGURE 7 Species ordination scores generated by DECORANA from the Spring and Sheep Mountain Ranges ......... 31 FIGURE 8 Species ordination of DECORANA from the lower Coleoqvne ecotone at Lucky Strike Canyon ......... 32 FIGURE 9 Density of Coleoqvne along its lower ecotone in Lucky Strike Canyon .................... 51 FIGURE 10 Soil moisture percentages at depths of 0-7 cm across the lower ecotone ........................ 52 FIGURE 11 Predawn and midday water potentials of Coleoqvne throughout the lower ecotone ............. 53 FIGURE 12 Soil organic matter content at depths of 0-7 cm across the lower ecotone ........................ 54 FIGURE 13A Soil temperatures at the soil surface and at depths of 15 cm in open spaces along the lower