Plant Ecology pptx

Ernst-Detlef Schulze · Erwin Beck · Klaus Mçller-Hohenstein Plant Ecology Ernst-Detlef Schulze · Erwin Beck · Klaus Mçller-Hohenstein Plant Ecology With 506 Figures, most of them in colour, and 101 Tables 12 Original title: Ernst-Detlef Schulze/Erwin Beck/Klaus Mçller-Hohenstein, Pflanzenækologie Copyright ° 2002 Spektrum Akademischer Verlag GmbH, Heidelberg ISBN 3-540-20833-X Springer-Verlag Berlin Heidelberg New York Library of Congress Control Number: 2004107209 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the German Copyright Law. Springer is a part of Springer Science+Business Media springeronline.com ° Springer Berlin ´ Heidelberg 2005 Printed in Germany The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Editor: Dr. Dieter Czeschlik, Heidelberg Desk editor: Dr. Andrea Schlitzberger, Heidelberg Production: Karl-Heinz Winter, Heidelberg Cover design: design & production GmbH, Heidelberg, Germany Cover illustration: Claus Diercks, Willy Giltmann, Hamburg, Germany Typsetting: K &V Fotosatz GmbH, Beerfelden 31/3150 543210±Printedonacid-free paper Professor Dr. Ernst-Detlef Schulze Max-Planck-Institute for Biogeochemistry P.O. Box 100164 07701 Jena Germany Professor Dr. Erwin Beck Department of Plant Physiology University of Bayreuth 95440 Bayreuth Germany Professor Dr. Klaus Mçller-Hohenstein Department of Biogeography University of Bayreuth 95440 Bayreuth Germany Translated by: Gudrun Lawlor, FIL Dr. Kirsten Lawlor Dr. David Lawlor 9 Burywick Harpenden Hertfordshire AL5 2AQ UK Content: This textbook starts at the level of the cell and molecular aspects of plant responses to the environment, which is never stress free. Building on this molecular ecophysiology, the organisation and regulation of metabolism of whole plants will be described from an autecolo- gical perspective. In the following parts, this book deals with the interactions with other or- ganisms at the level of the ecosystem. Finally, geographical and long-term conditions for the expansion and dynamics of plant populations and species on earth are discussed. The book closes with the element cycles on earth and thus stresses the influence of man on original, so- called natural ecosystems. As the book covers several different concep- tual levels, many aspects and facts will be illu- minated from very different viewpoints: the cell, the plant, the ecosystem, the zones of distribu- tion and earth as a whole. Thus, the authors have tried to fully consider the enormous width and complexity of plant ecology. The reader: The textbook is aimed at advanced students and their teachers. Knowledge in var- ious disciplines of natural sciences is expected, from molecular biology to the earth sciences. The authors have tried to recommend textbooks and articles from the relevant literature in each chapter. This ªfurther readingº is intended to deepen the relevant knowledge and to help de- velop an understanding in relation to neighbour- ing fields. Additionally, basic knowledge is revis- ited in concise box-type texts. Conceptual knowledge is abstracted and strengthened in ex- tensive summaries at the end of each section. Thanks: Writing this textbook has been a plea- sure, but has also cost the authors much of the one commodity which they lack most: time. A great deal of what could and should have been done was left by the wayside. We therefore ask all those whom we did not give enough of our time to make allowances, in particular our as- sociates and last, but not least, our families. Without the support and help of many collea- gues, friends and coworkers, it would not have been possible to finish this book in time so that it does not contain chapters which are outdated before publication. Particular thanks are given to Mrs Barbara Lçhker, without whose thorough editorial work this book probably would have never been completed. For the critical reading of individual chapters, for advice and pointers to the literature, the authors would like to thank many colleagues, in particular: A. Arneth (Jena), K. Beierkuhnlein (Bayreuth), C.M. P. Blum (Ut- recht), H. Bohnert (Urbana), U. Deil (Freiburg), W.H. O. Ernst (Amsterdam), S. Fettig (Bayreuth), E. Gloor (Jena), G. Guggenberger (Halle), F. Haakh (Stuttgart), U. Heber (Wçrzburg), H. W. Heldt (Gættingen), J. Kaplan (Jena), O. Kolle (Jena), U. Kçper (Bayreuth), O. L. Lange (Wçrzburg), W. Larcher (Innsbruck), C. Neûhæfer and G. Or- lich (Bayreuth), C. Ploetz (Wuppertal), M. Popp (Vienna), R. Voeseneck (Utrecht), R. Scheibe (Osnabrçck), W. Schulze (Tçbingen), E. Steudle (Bayreuth), C. Wirth (Jena) and W. Zech and P. Ziegler (Bayreuth). Special thanks are also extended to Springer- Verlag for having translated the original German book published by Spektrum Akademischer Ver- lag. Both publishers obliged most of the requests by the authors in a constructive manner and re- spected the individuality of the authors, even though they had to consider the homogeneity of the final product. The authors hope for a good reception of Plant Ecology by interested readers and welcome constructive criticism in the knowledge that the writing of a textbook about plant ecology in its entirety is an almost insurmountable task. E Detlef Schulze, Erwin Beck and Klaus Mçller-Hohenstein Bayreuth and Jena, October 2004 Preface Introduction 1 Chapter 1 Stress Physiology 5 1.1 Environment as Stress Factor: Stress Physiology of Plants 7 1.1.1 Abiotic and Biotic Environments CauseStress 7 1.1.2 Specific and Unspecific Reactions toStress 9 1.1.3 Stress Concepts 11 1.1.4 Perception of Stress and Creation ofSignals 13 1.1.5 How to Measure Stress on Plants? . . 16 1.1.6 Production of Stress-Tolerant Plants by Genetic Engineering? 16 1.1.7 Gene Silencing 19 1.2 Light 23 1.2.1 Visible Light 24 1.2.2 UV Radiation 37 1.3 Temperature 45 1.3.1 Temperature Ranges and Tempera- tures Limiting Life 45 1.3.2 Temperature-Dependent Biochemical Processes, Q 10 and Activation Energy 48 1.3.3 Temperature and Stability/Function of Biomembranes 49 1.3.4 Heat (Hyperthermy) 50 1.3.5 Cold 61 1.3.6 Frost 72 1.3.7 Concluding Comments 94 1.4 Oxygen Deficiency (Anaerobiosis and Hypoxia) 99 1.4.1 Energy Metabolism of Plants Lacking Oxygen 101 1.4.2 Anatomical-Morphological Changes DuringHypoxia 105 1.4.3 Post-anoxic Stress 114 1.5 Water Deficiency (Drought) . . 117 1.5.1 Water Balance of Drought-Stressed Cells 119 1.5.2 Cellular Reactions to Drought Stress 123 1.5.3 CAM (Crassulacean Acid Metabolism) . . . 135 1.5.4 Anatomical-Morphological Adapta- tiontoDrought 140 1.6 Salt Stress (Osmotic Stress) . . 145 1.6.1 Physiological Effects of Salt Stress (NaCl) 146 1.6.2 Adaptive Responses of Plant Cells toSaltStress 149 1.6.3 Avoidance of Salt Stress 171 1.7 Heavy Metals 175 1.7.1 Availability of Heavy Metals 176 1.7.2 Heavy Metal Deficiency ± Example Iron 176 1.7.3 Stress by Heavy Metal Ion Toxicity . 182 1.7.4 Reaction of Plants to Excess Supply of Heavy Metals 184 1.7.5 Heavy Metal Resistance (Tolerance) 191 1.7.6 Heavy Metal Extraction and Soil Decontamination by Plants (Phytomining, Phytoremediation) . . 191 1.8 Aluminium 195 1.8.1 Forms of Aluminium Available to Plants 196 1.8.2 Aluminium Toxicity 196 1.8.3 Al 3+ Resistance 200 1.8.4 Al 3+ Tolerance 203 1.9 Xenobiotica 207 1.9.1 Herbicides 210 1.9.2 Gaseous Air Pollutants 215 Contents 1.10 Biotic Stress: Herbivory, Infection, Allelopathy 235 1.10.1 Signal Chain in Wounding 235 1.10.2 Pathogen Attack and Defence 246 1.10.3 Allelopathy 250 Chapter 2 Autecology: Whole Plant Ecology . . 253 2.1 Thermal Balance of Plants . . 255 2.1.1 The Atmosphere as Habitat 257 2.1.2 Climate of Air Near the Ground . . . 263 2.1.3 Energy Balance of Leaves 269 2.1.4 Adaptation to Temperature Extremes 270 2.2 Water Relations of Plants 277 2.2.1 Water as an Environmental Factor . 277 2.2.2 Water Transport in the Plant 283 2.2.3 Regulation of Stomata 296 2.2.4 Transpiration of Leaves and Canopies 303 2.3 Nutrient Relations of Plants . 313 2.3.1 Availability of Soil Nutrients and Ion Uptake 313 2.3.2 Nitrogen Nutrition 324 2.3.3 Sulfur Nutrition 335 2.3.4 Phosphate Nutrition 337 2.3.5 Nutrition with Alkaline Cations . . . 338 2.4 Carbon Balance 347 2.4.1 Net Photosynthesis: Physiological and Physical Basis . . 347 2.4.2 Specific Leaf Area, Nitrogen Content and Photosynthetic Capacity 357 2.4.3 Response of Photosynthesis to Environmental Factors 361 2.4.4 Growth and Storage 373 2.4.5 C and N Balance in Different Types of Plants 379 Chapter 3 Ecology of Ecosystems 397 3.1 The Ecosystem Concept 399 3.1.1 What is an Ecosystem? 400 3.1.2 Boundaries of Ecosystems 400 3.1.3 Compartmentalisation 401 3.1.4 System Characteristics 401 3.2 Processes in Stands and Ecosystems 403 3.2.1 Self-Thinning 403 3.2.2 Reversible and Irreversible Site Changes Related to Resource Exploitation 406 3.2.3 Complexity and Non-linear Behaviour 409 3.2.4 Number of Species and Habitat Partitioning 411 3.2.5 Disturbances 417 3.3 The Biogeochemical Cycles . . 425 3.3.1 Water Turnover 426 3.3.2 Carbon Turnover 427 3.3.3 Nitrogen Cycle 438 3.3.4 Cation Turnover 444 3.4 Biodiversity and Ecosystem Processes 449 3.5 Case Studies at the Scale of Ecosystems 455 3.5.1 Soil Acidification and Forest Damage 456 3.5.2 Effect of Deciduous and Coniferous Forests on Processes in Ecosystems 460 3.5.3 Plants of Limestone and Siliceous Rocks 462 Chapter 4 Syndynamics, Synchorology, Synecology 465 4.1 Historic-Genetic Development of Phytocenoses and Their Dynamics 467 4.1.1 History of Vegetation to the End oftheTertiary 469 4.1.2 Change of Climate and Vegetation in the Pleistocene 472 4.1.3 Late and Postglacial Climate and Vegetation History 475 4.1.4 Changes in Vegetation Because of Human Influence 479 4.1.5 Basis of General Vegetation Dynamics 507 4.1.6 Stability of Plant Communities 534 VIII Contents 4.2 Synchorology: Basis of Spatial Distribution of Plants 541 4.2.1 Distribution of Plants 542 4.2.2 Basis of Spatial Distribution (Phytogeography) 548 4.2.3 Relationship Between Area and Species 555 4.2.4 Biodiversity 562 4.3 Interactions Between Vegeta- tion and Abiotic and Biotic Environments ± Synecology . . 579 4.3.1 Influences of Vegetation on the Site 580 4.3.2 Interactions Between Plants and Animals 585 4.3.3 Interactions Between Plants 602 Chapter 5 Global Aspects of Plant Ecology 623 5.1 Global Change and Global Institutions 625 5.2 Global Material Cycles 633 5.2.1 Water Cycle 633 5.2.2 Carbon Cycle 635 5.2.3 Nitrogen Cycle 636 5.2.4 Sulfur Cycle 638 5.3 Human Influence on Carbon Balance and Significance for Global Climate 641 5.4 Significance of Changes in Land Use for Carbon Cycles . . 649 5.4.1 Land Use and CO 2 Emissions 649 5.4.2 The Kyoto Protocol: Attempts To Manage the Global Carbon Cycle . . 651 5.4.3 Importance of Climate Change forEurope 659 5.5 Influence of Human Activities on Biodiversity 663 5.5.1 Decrease in Biodiversity 663 5.6 Socio-economic Interactions . 669 5.6.1 Syndromes 670 5.6.2 Evaluation of Risks to Biodiversity inEcosystems 673 Subject Index 679 a Contents IX The term ªecologyº was defined by Ernst Haeckel in 1906 in his book, Principles of Gener- al Morphology of Organisms, as follows: ªEcol- ogy is the science of relations of the organism to the surrounding environment which includes, in its broadest sense, all `conditions for exis- tence'. These conditions may be organic or inor- ganic; both are of the greatest importance for the form of organisms, because they force the organism to adapt.º Haeckel included in the science of ecology the areas physiology, morphology and chorology (the science of the distribution of organisms) to understand the ªconditions for existenceº and ªadaptationº. In this book, we try to comply with Haeckel's understanding of plant ecology and to include the breadth of ecology as it was demanded by Haeckel. Adaptation to the envi- ronment starts at the molecular and cellular lev- el where environmental conditions are detected and the responses to changes in the environment are accomplished. Starting from these physiolog- ical mechanisms, the morphological characteris- tics of organisms/plants become important at the level of the whole plant. Cellular metabolic reactions and structural (morphological and an- atomical) organisation are the biological ªtoolsº with which organisms make use of certain envi- ronmental conditions, avoid them or ªadaptº to them. The combination of physiological and morphological ªadaptationº is particularly im- portant for plants, as they are fixed in their hab- itat and the conditions for life are determined by the variety and numbers of the organisms of the ecosystem and not by the individual plant alone. These environmental conditions and the interaction of a plant with the environment de- termine ªfitnessº, i.e. the possibility for growth and reproduction in a spatial and temporal di- mension, thus resulting in an association with Haeckel's ªchorologyº. Haeckel's understanding of ecology was broader than our present botani- cal usage. The present book views ecology in as broad a context as Haeckel did, ranging from molecular stress physiology via ecology of whole organisms and the ecosystem to the temporal and spatial differentiation of vegetation. Figure 1 shows the relations between (cellu- lar) stress or ecophysiology, whole plant phys- iology and synecology (i.e. the ecology of vege- tation cover) and ecosystem science where other organisms, not only plants, are increasingly con- sidered. The interrelations between stress phy- siology, whole plant physiology and synecology are very close and obvious. In contrast, the path from stress physiology to ecosystems runs via whole plant ecology and synecology because morphology, i.e. the structure of plants, and the responses of populations are not primarily meta- bolic. Applied ecology includes all disciplines related to human activities. These include not only agriculture and forestry, but also global change. Agriculture and forestry contain also physiological aspects of high-yielding and pest- free varieties of crops and the biological interac- tions between crop plants and other organisms, Introduction Ecology Stress physiology Whole plant ecology Synecology Ecology of ecosystems Applied ecology, global change n Fig. 1. Areas of ecology and their position within bot- any, ecosystem studies and in applied ecology e.g. for pollination. Research on global change also includes the assessment of possible manage- ment systems for earth with respect to their ef- fects on climate and maintaining biodiversity. Research on global change leads to model pre- dictions on future effects of human activities. In this book, an attempt is made, for the first time, to bring together and clearly organise the large subdisciplines of plant ecology. We start from the molecular stress and ecophysiology of plants in the broadest analysis yet attempted. Chapter 1 lays down the molecular basis for ecological ªadaptationsº to all essential environ- mental factors. This ranges from climatic factors via salt stress in the soil to environmental pollu- tants. The stress theory considers the basic pos- sibilities of stress responses resulting from strains and leading to resistance; finally, these provide the basis for understanding adaptive ra- diation of genotypes, and the processes leading to the evolution of new species. Plants not only react to stress in the sense of a response, the so- called feed-back reponse. There are also pre- paratory adaptations to changing environmental conditions, the so-called feed-forward reactions, setting off before an organism is stressed (e.g. pre-winter frost hardening). In both cases, signal chains are activated, leading to changes in the physiological/cell biological performance of plants, enabling them to continue to exist under new conditions. The response to one stress fac- tor often protects the organism also from dam- age by other stresses (ªcross-protectionº). This results in responses to a variety of stresses re- sulting from a changing environment where not one single factor (e.g. heat or drought), but mul- tiple stress types are acting in combination. The basic principles of avoidance (as a sort of feed- forward response) and tolerance (as a sort of feed-back response) to stress are not only re- stricted to the level of ecophysiology, but occur also in responses of whole plants, in the distribu- tion of species and plant communities, particular- ly at extreme sites. At the level of the organism, we consider the plant as a whole and the relations between its organs from the root to the leaf, flower and seed. At the level of whole plant ecology new, not (primary) metabolic characteristics are added: although these are genetically deter- mined, they may be modified within limits. These include plant structures including size and the life cycle (phenology, life span, strate- gies for reproduction and distribution). Because of these strategies, certain species are able to avoid extreme conditions and use or change their habitat. Annual plants form the largest proportion of plant species in dry areas. How- ever, their active life is limited to favourable conditions after rain, even if this only occurs sporadically, perhaps only every few years or even decades. In contrast, perennial species have mechanisms that regulate the water relations and enable survival in unfavourable climatic periods. These include, for example, special leaf and root anatomy that allows the species to sur- vive with intact shoot systems or to change their site conditions. Hydraulic lift, for example, en- ables roots to transport water from deep soil layers to the upper horizons and thus moisten the upper soil layers. In temperate climates, the accumulation of carbon in the soil changes site fertility. The scope for ªadaptationsº by whole plants is very broad, as are the responses of cells to stress. They range from leaf structure and leaf movement, via the formation of variably di- mensioned vessels in the stem, to differentiation of the roots. In Chapter 2, the use of resources by whole plants is discussed. This includes the plant±water relations, the heat and nutrient bal- ances and the carbon relations. Cellular metabolism and structural character- istics are not only the basis for the spatial and temporal patterns of plant species, dealt within synecology (Chap. 4), but also the basis for ele- ment cycles in ecosystems, which are charac- terised by the diversity of species and forms of or- ganisation. These include indirect interactions be- tween individual plants and other plant species. Here applies the wisdom that: ªEven the most pious cannot live in peace if it does not please the nasty neighbourª. Competition exists in the effective use of resources on limited space. If the resources become scarce, ªefficiencyº means a better use of limiting resources at the cost of the neighbour. This, of course, does not always imply saving resources or using them most eco- nomically. Indeed, it may be more useful to use more resources than required, if this brings ad- vantages in competition with the neighbours. Growth also plays an important role in ecosys- tems, and the ªecological equilibriumº of an eco- system probably does not exist in ªnatureº as it is. Metabolic cycles in ecosystems are not as closed as previously assumed. This means that the actual status as it may be observed as a mo- mentary picture of a system is in the long term very dynamic. Not all processes of a system move 2 Introduction linearly in one direction. There are strengthening and weakening processes with a consequential complex, non-linear temporal behaviour. The sci- entific basis of ecosystems is, for the first time, presented in Chapter 3 of this volume. General conclusions are drawn about how individual or- ganisms interact within the diversity of vegeta- tion. This leads to the question about the degree to which vegetation is more than the sum of its in- dividual plants. Many characteristics of vegetation result from material fluxes which dictate the per- formance of individual plants. For example, the ªaero-dynamic roughnessº of the surface of vege- tation determines coupling to the meteorological conditions in the atmosphere and thus deter- mines the survival of plant individuals or a spe- cies in the vegetation. It is only by large numbers of individuals of the same species which, through distribution of seeds or other ways of propaga- tion, determine the habitat in relation to a dy- namic diversity of other species. Synecology is the next higher level of plant ecology, extending to populations based on the strategies of propagation and distribution. Syn- ecology does not consider the fate of a single in- dividual, but the dynamic spatial and temporal behaviour of populations, including population growth, homoeostasis and decline. Only in ex- ceptional cases does a single species form a veg- etation. Generally, natural vegetation includes a diversity of species which make complementary use of the available resources. In synecology, the broad spectrum of responses at the cellular and whole plant level is replaced by the enormous diversity of species (350,000 species of vascular plants) which determine in different proportions the composition of the vegetation cover of the earth. In Chapter 4, the historical and spatial di- mensions of species distributions and their bio- logical interactions are discussed. Combining the ecology of ecosystems with the field of synecology enables us to understand also the distribution of species. Both the poten- tial and actual areas ( Fig. 2) are determined by several parameters. For example, considering only the carbon balances, a plant species could grow on a much larger area than the region in which it actually reproduces. However, even this region is limited by different types of competi- tion with other species, so that the area even- tually occupied is even further restricted. Agri- cultural crop plants (maize, beans, wheat, potato, soya and many others) are an interesting exam- ple of evolution in a geographically limited area (the so-called genetic centres of origin), but these species are now distributed worldwide after do- mestication and management by humans. The science of geobotany relates to global as- pects in plant ecology, which are included in the term global change, where the direct and indi- rect influences of man through land use, changes in land use and the subsequent changes a Introduction 3 n Fig. 2. Distribution of a species depends on different environmental factors. The actual distribution area is significantly smaller than the potential areas of distribution which are reached without competition at the extreme limits of flowering or at the boundaries of a positive material balance. In the example shown, temperature is the dominant factor, but this may differ in other cases. According to the species, the limits of distribution change dry wet cold warm shade sunny acid alkaline Without competition Flowering and fruiting possible Limits of a positive carbon balance Temporal and geographical range with competition [...]... development of molecular plant ecophysiology Based on these considerations, the book deals with the main areas of plant ecology in the following chapters: · · · · · Stress physiology Whole plant physiology Ecology of ecosystems Synecology Global aspects of plant ecology Chapter Stress Physiology 1 The cold tropics: The author of this chapter has been working for more than 20 years on plant stress in high... thylakoid membrane proteins in green plants Biochim Biophys Acta (Bioenergetics) in press · Huner NPA, Úquist G, Sarhan F (1998) Energy balance and acclimation to light and cold Trends Plant Sci 3:224±230 · Long SR, Humphries S (1994) Photoinhibition of photosynthesis in nature Annu Rev Plant Physiol Plant Mol Biol 45:633±662 · Lçttge U (1997) Physiological ecology of tropical plants Springer, Berlin Heidelberg... silent genes: transgene silencing, gene regulation and pathogen control Trends Plant Sci 4:340±347 · Meyer P, Saedler H (1996) Homology-dependent gene silencing in plants Annu Rev Plant Physiol Plant Mol Biol 47:23±48 In several cases, the transferred genes were not expressed, although the transformation of the receiver plant had been successful This failure occurred frequently when the genes were... the mechanisms of gene silencing References Bender J (2004) DNA methylation and epigenetics Annu Rev Plant Biol 55:41±68 Finnegan EJ, Genger RK, Peacock WJ, Dennis ES (1998) DNA-methylation in plants Annu Rev Plant Physiol Plant Mol Biol 49:223±248 Fitter AH, Hay RKM (1987) Environmental physiology of plants Academic Press, London, p 8 Hansen J, Beck E (2002) Kålte und Pflanze: Updating classical views... Larcher W (ed) (2003) Physiological plant ecology, 4th edn (chapter: Plants under stress) Springer, Berlin Heidelberg New York, pp 345±450 · Robertson D (2004) VIGS vectors for gene silencing: many targets, many tools Annu Rev Plant Biol 55:495±519 · Stokes T (2003) DNA-RNA-protein gang together in silence Trends Plant Sci 8:53±55 · Taiz L, Zeiger E (eds) (2002) Plant physiology, 3rd edn (chapter: Stress... treated plants 25 20 15 10 NaCl 5 Control 0 0 1 2 3 4 5 Duration of salt treatment (days) B - 2 -1 0 1 2 3 4 5 Duration of salt treatment (days) n Fig 1.1.4 Frost hardening through salt treatment Cuttings of potato plants (Solanum commersonii Dun Pl 458317) were grown in Murashige-Skoog medium to which NaCl was added (100 mM final concentration) A Frost hardiness of plants and B ABA content of plants... 1.1.6 Production of Stress-Tolerant Plants by Genetic Engineering? Recommended Literature · Holmberg N, Bçlow L (1998) Improving stress tolerance in plants by gene transfer Trends Plant Sci 3:61±66 · Pilon-Smits EAH, Ebskamp MJM, Paul MJ, Jeuken MJW, Weisbeek PJ, Smeekens SCM (1995) Improved performance of transgenic fructan-accumulating tobacco under drought stress Plant Physiol 107:125±130 · Tarczynski... protect the embryo from drying out during seed maturation Currently, not all crop plants are useful targets for stable genetic transformation This ap- a 17 Production of Stress-Tolerant Plants by Genetic Engineering? Box 1.1.1 Quantification of damage to plant tissues 1 Counting necrotic areas after stress application Plant tissue, for example, pieces of a leaf, are exposed to a defined stress and then... the morning of a day during the rainy season (in July) at about 4700 m on Mt Kenya, shows that man and plants can suffer from cold, even right on the equator Several species of flowering plants can grow even at this altitude in moist sites 1.1 Environment as Stress Factor: Stress Physiology of Plants Plants are bound to places They, therefore, have to be considerably more adaptable to stressful environments... drives plant stress genes? Trends Plant Sci 8:99±102 · Bohnert HJ, Nelson DL, Jensen RG (1995) Adaptations to environmental stress Plant Cell 7:1099±1111 · Couzin J (2002) Breakthrough of the year Small RNAs make big splash Science 298: 2296±2297 · http://www.ambion.com/hottopics/rnai RNA interference · http://www.nature.com/nature/fow/ 000316.html RNA interference · Larcher W (ed) (2003) Physiological plant . between crop plants and other organisms, Introduction Ecology Stress physiology Whole plant ecology Synecology Ecology of ecosystems Applied ecology, global change n Fig. 1. Areas of ecology and. phy- siology, whole plant physiology and synecology are very close and obvious. In contrast, the path from stress physiology to ecosystems runs via whole plant ecology and synecology because morphology,. Synecology . . 579 4.3.1 Influences of Vegetation on the Site 580 4.3.2 Interactions Between Plants and Animals 585 4.3.3 Interactions Between Plants 602 Chapter 5 Global Aspects of Plant Ecology