On the economy of plant form and function

Size: px

Start display at page:

Download "On the economy of plant form and function"

Katherine Norman
5 years ago
Views:

1 On the economy of plant form and function M Proceedings of the Sixth Maria Moors Cabot Symposium, "Evolutionary Constraints on Primary Productivity: Adaptive Patterns of Energy Capture in Plants," Harvard Forest, August 1983 Edited by Thomas J. Givnish Department of Botany, University of Wisconsin The right of the University of Cambridge to print and sell all manner of books was granted by Henry VIII in The University has printed and published continuously since IS84. CAMBRIDGE UNIVERSITY PRESS Cambridge New York Port Chester Melbourne Sydney

2 Contents Acknowledgments List of contributors page xv xvi Introduction 1 On the use of optimality arguments 3 Part I Economics of gas exchange 11 Photosynthetic adaptations 17 Water and nutrient acquisition 20 Water transport and maintenance of turgor 21 1 The photosynthesis - nitrogen relationship in wild plants 25 Christopher Field and Harold A. Mooney A survey: the photosynthesis-nitrogen relationship in natural vegetation 28 Nitrogen-use efficiency 34 Correlation or cause 39 Deciding among the three hypotheses 41 Nitrogen-based limits to A nax 42 Limitations by physical factors 45 Integration and conclusions 49 2 Modifications of solar-radiation absorption patterns and implications for carbon gain at the leaf level 57 fames R. Ehleringer and Kenneth S. Werk Introduction 57 What are the observed patterns in the field? 60 Community-level patterns of leaf absorptance and leaf angle 60 Intrageneric patterns 62 Seasonal trends in leaf absorptance 62 Variation in leaf angle and azimuth 64

3 vi CONTENTS Nonrandom leaf azimuths Leaf solar tracking Costs and benefits of morphological changes for photosynthesis and transpiration Leaf absorptance Leaf solar tracking Paraheliotropic leaf movements Steep fixed leaf angles Steep leaf angles and nonrandom azimuths Conclusions 3 Form and orientation in relation to PAR interception by cacti and agaves Park S. Nobel Introduction Materials and methods Plant material Photosynthetically active radiation Cladode orientation Tissue acidity: C0 2 exchange Results and discussion Expected PAR levels: latitudinal effects PAR influences on C0 2 uptake and acidity changes Orientation ofcladodes on platyopuntias Other correlations between cactus morphology and PAR PAR distribution in agave canopies Summary and conclusions 4 Unusual strategies of light absorption in rain-forest herbs David W. Lee Introduction Plant adaptations and understory light climates Red undersurfaces Epidermal lenses Blue iridescence Developmental control Summary 5 Economics of carbon fixation in higher plants Ian R. Cowan Introduction Use of nitrogen Investment in two chloroplast enzymes Functions of the two enzymes

4 Contents Optimal partition of nitrogen 137 Extension to other enzymes: interaction with water use 139 Balance of carbon fixation and water loss 144 A paradigm of stomatalfunction 144 Examples of optimal stomatal control / 146 Some constraints on control 150 Avoidance of drought 152 Relation between carbon fixation and likelihood of desiccation 152 Optimal responses ofstomata to variations in soil water content 155 Optimal allocation of carbon between root and shoot 159 Conclusions 161 Appendix I: Carbon dioxide fixation with facilitated transfer 162 Appendix II: Rate of assimilation as a function of Nj and N c 164 Appendix III: Variation of and A with leaf conductance 165 Appendix IV: Probability distribution of soil water deficit 166 Appendix V: Maximization of probable average rate of assimilation, A Optimal stomatal conductance, allocation of energy between leaves and roots, and the marginal cost of transpiration 171 Thomas f. Givnish Qualitative effects of stomatal resistance and leaf allocation 173 Quantitative model for optimal stomatal resistance and fractional leaf allocation 175 Optimality conditions 177 Quantitative prediction ofr % and f in Phaseolus vulgaris 179 Predicted relationships between A and g 192 Marginal cost of transpiration V 195 Calculated value 195 Equivalence with b and da/de 196 Observed versus expected values of da/de 199 Extension to time-varying environments 201 Extension to other traits affecting gas exchange 203, Summary Internal leaf structure: a three-dimensional perspective 215 David F. Parkhurst Introduction 215 Palisade and spongy mesophyll 216 A general mathematical model for CO 2 diffusion inside leaves 218 An earlier model 218 vii

5 viii CONTENTS Generalized model Example application Purposes of the model Solution by the finite-element method CO 2 concentration profiles inside leaves: a threedimensional phenomenon Calculated photosynthesis rates Experiments on the model A 2 4 -factorial sensitivity test Varying the size of the substomatal chamber Optimal mesophyll structure, or variations on a theme by nature Other questions about internal structure Leaf thickness Stomatal spacing and epidermal thickness Light Other factors Conclusions Summary Competing root systems: morphology and models of absorption 251 Martyn M. Caldwell and fames H. Richards Introduction: the costs of competition 251 Perspective on root competition: contribution of models 253 Cylindrical-flow models and parameter sensitivity 25 Competition between roots: considerations in two dimensions 2 Three dimensions and other complications 261 Conclusions from uptake models for competition between roots 2 Root density and morphometrics > 264 Density and location of roots: an example of two bunchgrasses 26 Morphometrics of root systems Belowground costs: hydraulic conductance 275 Edwin L. Fiscus Benefits 275 Theory of hydraulic conductance 275 Functional interpretation of parameters 277 Combined volume and solute flux 279 Differential resistance 281 Costs 283 Growth model 284 Cost of conductance 291 Final comments 293

6 Contents 10 Economy of symbiotic nitrogen fixation 299 John S. Pate Introduction 299 Theoretical costs of the nitrogenase:hydrogenase functions of N 2 -fixing organisms 300 Measurement of energy costs of symbiotic N 2 fixation: case study of the legume nodule 303 Cost of symbiotic N 2 fixation versus other forms of assimilation or acquisition of N Cost-benefit analysis of symbiotic N 2 fixation under ecological conditions 315 Conclusions and summary Ecological patterns of xylem anatomy 327 Pieter Baas Introduction 327 Methodology 328 The evolutionary basis 329 Survey of ecological trends 332 Vessel elements 332 Fibers 336 Axial parenchyma 339 Rays 339 Functional significance of the ecological trends 340 Vessels: safety and efficiency in the ascent of sap 340 Concepts of vulnerability and mesomorphy 344 Fibers and parenchyma: mechanical strength and carbohydrate metabolism 346 Growth rate, ecological trends, and wood structure 347 Wood structure and primary productivity 348 Conclusions \ Turgor maintenance in Hawaiian Dubautia species: the role of variation in tissue osmotic and elastic properties 353 RobertH. Robichaux, KentE. Holsinger, and Suzanne R. Morse Introduction 353 Relationship to diurnal turgor maintenance 354 Phenotypic variation within one species 358 Variation among two species and their hybrid 360 Variation among six additional species 363 Mechanistic basis of the variation in tissue elastic properties 367 Influence of cell size 367 Influence of cell-wall composition 369 Influence ofapoplasmic water loss 369 Conclusion 374 ix

7 x CONTENTS Appendix I: An expression for the bulk tissue elastic modulus when water is lost from the apoplasm 374 Appendix II: Estimating the necessary loss of apoplasmic water to make two sets of observations equivalent Adaptations for water and thermal balance in Andean giant rosette plants 381 Frederick Meinzer and Guillermo Goldstein Stem pith Hydraulic connections and relative capacitance Available water Relative capacitance and water relations in the field Intraspecific relationships Marcesent leaves Possible costs Marcesent leaves and survival Leaf pubescence Characteristics Coupling of leaf temperature to environmental variables Leaf pubescence and stomatal behavior Morphological adaptation and constraints on functioning and behavior Stem pith and marcesent leaves Leaf pubescence Conclusions Part II Economics of support Evolution of plant life forms John A. Raven Introduction Classification of life forms Photon flux density requirements for photolithotrophs of various life forms Plant construction types Planktophytes Benthic algae Terrestrial vascular plants Evolution of life forms: the fossil record Conclusions Appendix I: The quantum requirement of net CO 2 fixation

8 contents 15 Branching patterns and angles in trees Jack B. Fisher Introduction Structural basis Primary orientation Primary pattern Branch dimorphism Later changes Tree architecture Relationship between axis position and leaf surface Factors determining leaf position Effects of branching on leaf surface Problems of plasticity Simulations of tree branching Adaptive significance Optimization studies Ecological correlations Conclusions XI Biomechanical constraints on crown geometry in forest herbs 525 Thomas J. Givnish Adaptive significance of leaf height in forest herbs 526 Tests of the model 528 Functional relation of leaf height to herbaceous cover 528 Quantitative agreement with theory 529 Effects of leaf phenology 531 Economy of branching in Podophyllum 533 Methods. 535 Biomechanical principles i 536 Description of sexual and asexual shoots 540 Economy of branching versus not branching 541 Optimal branching angle 551 Optimal branching height 554 Competitive advantage of the arching growth form on slopes 557 Methods 560 Results 561 Leaf shape in violets 565 General principles regarding cordate leaf bases 568 The case of Viola 571 Discussion 573 Summary 575

9 xii CONTENTS Appendix I: Vein cost of one versus two leaves in Podophyllum 578 Appendix II: Vein cost of leaf inequality in Podophyllum 579 Appendix III: Vein cost of leaf assymetry in Podophyllum The roles of carbon balance and branching pattern in the growth of woody species 585 E.-Detlef Schulze, Manfred Kuppers, and Rainer Matyssek Introduction 585 Results and discussion 587 Relationships between C0 2 assimilation and primary production in deciduous Fagus sylvatica and evergreen Picea abies 587 Growth and competition as related to plant architecture 589 Growth as related to plant water relations 596 Growth as related to water and nutrient relations 598 Conclusions Seaweeds in moving water: form and mechanical function 603 Mimi A. R. Koehl Water flow encountered by benthic algae 603 Flow habitats 603 Flow microhabitats 604 Hydrodynamic forces on algae 606 Drag on algae in water currents 606 Forces on algae in waves 609 Deflection and breakage 611 Stress in an algal thallus 612 Deformation of an alga in moving water 616 Breakage of an alga in moving water \ 619 Tradeoffs ' 622 Tradeoff between drag reducation and photosynthesis 622 Tradeoff between unbreakability and photosynthesis 625 Conclusions 626 Appendix I: Notation Functional geometry of seaweeds: ecological consequences of thallus layering and shape in contrasting light environments 635 Mark E. Hay Introduction 635 Morphological patterns of terrestrial vegetation 639 Functional morphology of seaweeds 642

10 Contents Thallus arrangement, shape, and transparency 642 Field tests of the hypotheses 647 Study site and organisms 647 Growth rate and seasonality 650 Physiology 653 Colonization 655 Competitive ability 659 Summary 661 Part HI Economics of biotic interactions Costs of defense and their effects on plant productivity 681 Sherry L. Gulmon and Harold A. Mooney Introduction 681 Direct costs of defense 681 Indirect costs of defense 684 Effects of varying carbon acquisition and allocation 690 Nitrogen and defense costs 693 Storage and defense costs 695 Summary 695 xiii Index 699

1 Soil Factors Affecting Nutrient Bioavailability... 1 N.B. Comerford

Contents 1 Soil Factors Affecting Nutrient Bioavailability........ 1 N.B. Comerford 1.1 Introduction........................... 1 1.2 Release of Nutrients from the Soil Solid Phase........ 2 1.3 Nutrient