<I>Equisetum Giganteum</I>
Total Page:16
File Type:pdf, Size:1020Kb
Florida International University FIU Digital Commons FIU Electronic Theses and Dissertations University Graduate School 3-24-2009 Ecophysiology and Biomechanics of Equisetum Giganteum in South America Chad Eric Husby Florida International University, [email protected] DOI: 10.25148/etd.FI10022522 Follow this and additional works at: https://digitalcommons.fiu.edu/etd Recommended Citation Husby, Chad Eric, "Ecophysiology and Biomechanics of Equisetum Giganteum in South America" (2009). FIU Electronic Theses and Dissertations. 200. https://digitalcommons.fiu.edu/etd/200 This work is brought to you for free and open access by the University Graduate School at FIU Digital Commons. It has been accepted for inclusion in FIU Electronic Theses and Dissertations by an authorized administrator of FIU Digital Commons. For more information, please contact [email protected]. FLORIDA INTERNATIONAL UNIVERSITY Miami, Florida ECOPHYSIOLOGY AND BIOMECHANICS OF EQUISETUM GIGANTEUM IN SOUTH AMERICA A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in BIOLOGY by Chad Eric Husby 2009 To: Dean Kenneth Furton choose the name of dean of your college/school College of Arts and Sciences choose the name of your college/school This dissertation, written by Chad Eric Husby, and entitled Ecophysiology and Biomechanics of Equisetum Giganteum in South America, having been approved in respect to style and intellectual content, is referred to you for judgment. We have read this dissertation and recommend that it be approved. _______________________________________ Bradley C. Bennett _______________________________________ Jack B. Fisher _______________________________________ David W. Lee _______________________________________ Leonel Da Silveira Lobo O'Reilly Sternberg _______________________________________ Steven F. Oberbauer, Major Professor Date of Defense: March 24, 2009 The dissertation of Chad Eric Husby is approved. _______________________________________ choose the name of dean of your college/school Dean Kenneth Furton choose the name of your college/school College of Arts and Sciences _______________________________________ Dean George Walker University Graduate School Florida International University, 2009 ii © Copyright 2009 by Chad Eric Husby All rights reserved. iii ABSTRACT OF THE DISSERTATION ECOPHYSIOLOGY AND BIOMECHANICS OF EQUISETUM GIGANTEUM IN SOUTH AMERICA by Chad Eric Husby Florida International University, 2009 Miami, Florida Professor Steven F. Oberbauer, Major Professor Equisetum giganteum L., a giant horsetail, is one of the largest living members of an ancient group of non-flowering plants with a history extending back 377 million years. Its hollow upright stems grow to over 5 m in height. Equisetum giganteum occupies a wide range of habitats in southern South America. Colonies of this horsetail occupy large areas of the Atacama river valleys, including those with sufficiently high groundwater salinity to significantly reduce floristic diversity. The purpose of this research was to study the ecophysiological and biomechanical properties that allow E. giganteum to successfully colonize a range of habitats, varying in salinity and exposure. Stem ecophysiological behavior was measured via steady state porometry (stomatal conductance), thermocouple psychrometry (water potential), chlorophyll fluorescence, and ion specific electrodes (xylem fluid solutes). Stem biomechanical properties were measured via a 3-point bending apparatus and cross sectional imaging. Equisetum giganteum stems exhibit mechanical characteristics of semi-self-supporting plants, requiring mutual support or support of other vegetation when they grow tall. The mean elastic moduli (4.3 Chile, 4.0 Argentina) of E. giganteum in South America is by far the iv largest measured in any living horsetail. Stomatal behavior of E. giganteum is consistent with that of typical C3 vascular plants, although absolute values of maximum late morning stomatal conductance are very low in comparison to typical plants from mesic habitats. The internode stomata exhibit strong light response. However, the environmental sensitivity of stomatal conductance appeared less in young developing stems, possibly due to higher cuticular conductance. Exclusion of sodium (Na) and preferential accumulation of potassium (K) at the root level appears to be the key mechanism of salinity tolerance in E. giganteum. Overall stomatal conductance and chlorophyll fluorescence were little affected by salinity, ranging from very low levels up to half strength seawater. This suggests a high degree of salinity stress tolerance. The capacity of E. giganteum to adapt to a wide variety of environments in southern South America has allowed it to thrive despite tremendous environmental changes during their long tenure on Earth. v TABLE OF CONTENTS CHAPTER PAGE 1. INTRODUCTION: SIGNIFICANCE OF EQUISETUM GIGANTEUM ECOPHYSIOLOGY AND BIOMECHANICS.................................................................. 1 Key questions addressed in this research ........................................................................ 3 1. What biomechanical adaptations allow E. giganteum to thrive and grow tall in environments as harsh and exposed as the Atacama Desert?....................................... 3 2. How do giant horsetail stomata behave under field conditions?............................. 3 3. How does Equisetum giganteum cope with high groundwater salinity stress in the valleys of the Atacama Desert?.......................................................................... 4 LITERATURE CITED.................................................................................................... 6 2. LITERATURE REVIEW: BIOLOGY OF EQUISETUM AND THE GIANT HORSETAILS .................................................................................................................... 8 The genus Equisetum....................................................................................................... 8 Morphology of Equisetum............................................................................................... 9 Unique characteristics of the genus Equisetum among vascular plants ........................ 11 Lateral branch origin .................................................................................................. 11 Stomatal structure....................................................................................................... 11 Elaters on spores......................................................................................................... 12 Silicon a required nutrient.......................................................................................... 12 Rhizome architecture.................................................................................................. 12 Fossil history of the Sphenopsids .................................................................................. 12 Distribution and taxonomy of Equisetum...................................................................... 17 Ecology, physiology and reproductive biology of Equisetum ...................................... 20 Sexual reproduction.................................................................................................... 20 Vegetative reproduction ............................................................................................. 22 Adventitious rooting as an adaptation to disturbance ................................................ 24 Adaptations to waterlogged soil and anaerobic conditions........................................ 25 Soil preferences and nutrient cycling......................................................................... 27 Silicon requirement .................................................................................................... 29 Mycorrhizae and root hairs ........................................................................................ 30 Nitrogen fixation ........................................................................................................ 31 Allelopathy................................................................................................................. 31 Hydathodes and guttation........................................................................................... 32 The giant horsetails........................................................................................................ 32 Taxonomy of the giant horsetails............................................................................... 34 Misidentification of herbarium specimens and living plants ..................................... 36 Ecology of the giant horsetails................................................................................... 37 LITERATURE CITED.................................................................................................. 45 3. BIOMECHANICS OF EQUISETUM GIGANTEUM L. STEMS FROM CONTRASTING ENVIRONMENTS IN SOUTH AMERICA....................................... 55 vi Abstract.......................................................................................................................... 55 Introduction ................................................................................................................... 56 Objectives of this study.............................................................................................. 59 Objective 1...........................................................................................................