The question "Why are there so many species?" has puzzled ecologist for a long time. Initially, an academic question, it has gained practical interest by the recent awareness of global biodiversity loss. Species diversity in local ecosystems has always been discussed in relation to the problem of competi tive exclusion and the apparent contradiction between the competitive exclu sion principle and the overwhelming richness of species found in nature. Competition as a mechanism structuring ecological communities has never been uncontroversial. Not only its importance but even its existence have been debated. On the one extreme, some ecologists have taken competi tion for granted and have used it as an explanation by default if the distribu tion of a species was more restricted than could be explained by physiology and dispersal history. For decades, competition has been a core mechanism behind popular concepts like ecological niche, succession, limiting similarity, and character displacement, among others. For some, competition has almost become synonymous with the Darwinian "struggle for existence", although simple plausibility should tell us that organisms have to struggle against much more than competitors, e.g. predators, parasites, pathogens, and envi ronmental harshness.

This work is the first monograph devoted solely to "Bombax ceiba," popularly known as the Red Silk Cotton Tree. Consisting of seven chapters, it covers all relevant aspects of this plant, from its historical and spiritual importance, to its botanical characterization, pharmacognostical details and ethnobiological uses, to its scientific validation in various animal and human studies. Each part of the tree is of medicinal value and possesses many novel chemical constituents such as shamimicin, bombasin, bombamalone, bombamaloside etc. along with other bioactive secondary metabolites. The book presents the chemical structures of the most important constituents and highlights various pharmacological activities, predominantly antioxidant, anti-inflammatory, anti-mutagenic, hypoglycemic, hypotensive, hepatoprotective and fibrinolytic, which may prove to be a source for the development of a novel phyto-pharmaceutical agent to treat diabetes, heart disease and cancer. In addition, separate chapters deal with the commercial and ecological significance of "B. ceiba," as well as a case study on its conservation. Numerous color illustrations are included to identify the plant and to justify its nickname, the Little Bird s Cafeteria . "

I have spent less time in the arid zone in the last few years than I did during the 1960's, 1970's and early 1980's. This results from a progression through age and a career structure which gradually shifted the emphasis of my work from being essentially field-oriented to essentially office-hound. When, therefore, I was asked by John Cloudsley-Thompson to undertake the writing of this hook I hesitated for two reasons. One reason was that, although I now had access to good library facilities and kept up with the literature on the arid zones and their fauna, I was not sure that a sedentary and pleasant life in a temperate highland island in tropieal Africa would provide a mental attitude suitable to writing a hook which related to areas where life is usually nomadie and often extremely disagreeable. The other reason was that I was uncertain whether I could devote the time necessary to researehing and writing the hook on top of my professional (which now specifical ly excluded research in the arid zones and on camels) and social (new-found and time-consuming) commitments. In the event I accepted and the fates were kind to me. By some peculiar combination of circumstances I was given the opportunity to spend a considerable part of the first half of 1988 in some of the driest areas of the globe. I had already visited all of the locations used for the construction of Fig. 2."

Potato is the fourth major staple food in the world and is still rapidly gaining importance, especially in the tropics. In May, 1994 the second international potato modelling conference was held in Wageningen, the Netherlands, as a summerschool of the C. T. de Wit Graduate School. The conference was sponsored by DLO, SCRI, SSCR, W AU and the LEB-Fund. Over 80 scientists participated, coming from 16 countries. Of each crop physiological and modelling subject, a leading scientist was requested to write a review of the most recent developments in his or her field. The reviews, with highlights from the authors' own work, are such that the physiological work described is of interest to the modeller and the modelling work to the crop physiologist. Applications of the quantitative approach are also reviewed in the concluding chapters that deal with decision support systems, breeding and agro-ecological zoning. An outstanding point of this book is that both the crop ecology and the modelling of a broad range of biotic and abiotic factors are treated by scientists representing groups which are specialized in the subject. The two related disciplines met during the conference and thus wrote the chapters with each other's interest in mind. The book highlights the limitations for potato growth and development from the viewpoints of both the crop physiologist and the crop-systems analyst.

Large-scale experimentation allows scientists to test the specific responses of ecosystems to changing environmental conditions. Researchers at Oak Ridge National Laboratory together with other Federal and University scientists conducted a large-scale climatic change experiment at the Walker Branch Watershed in Tennessee, a model upland hardwood forest in North America. This volume synthesizes mechanisms of forest ecosystem response to changing hydrologic budgets associated with climatic change drivers. The authors explain the implications of changes at both the plant and stand levels, and they extrapolate the data to ecosystem-level responses, such as changes in nutrient cycling, biodiversity and carbon sequestration. In analyzing data, they also discuss similarities and differences with other temperate deciduous forests. Source data for the experiment has been archived by the authors in the U.S. Department of Energy's Carbon Dioxide Information and Analysis Center (CDIAC) for future analysis and modeling by independent investigators.

Latest figures suggest that approximately 20% of the world's population of six billion is malnourished because of food shortages and inadequate distrib ution systems. To make matters worse, it is estimated that some 75 billion metric tons of soil are removed annually from the land by wind and soil ero sion, much of it from agricultural land, which is thereby rendered unsuitable for agricultural purposes. Moreover, out of a total land area under cultivation 9 6 of approximately 1. 5 x 10 ha, some 12 x 10 ha of arable land are destroyed and abandoned worldwide each year because of unsustainable agricultural practices. Add to this the fact that the world population is increasing at the rate of a quarter of a million per day, and the enormity of the task ahead becomes apparent. To quote the eminent wheat breeder E. R. Sears, It seems clear that plant geneticists can look forward to an expanded role in the 21st century, particularly in relation to plant improvement. The suc cess of these efforts may go a long way towards determining whether the world's increasing billions of humans will be adequately fed. Food for an ever-increasing population will have to be produced not only from an ever-diminishing, but from what will become an ever-deteriorating land resource unless justifiable environmental concerns are taken into account.

In view of the massive change in the area of distribution of many world biota across classical biogeographical realms, and of the drastic restructuring of the biotic components of numerous ecosystems, the Scientific Committee on Problems of the Environment (SCOPE) decided at its general Assembly in Ottawa, Canada, in 1982 to launch a project on the 'Ecology of Biological Invasions'. Several regional meetings were subsequently organized within the framework of SCOPE, in order to single out the peculiarities of the invasions that took place in each region, the behaviour of their invasive species and the invasibility of their ecosystems. Most noteworthy among such workshops were one in Australia in August 1984, one concerning North America and Hawaii in October 1984, and one dealing with southern Africa in November 1985. A leitmotiv of these workshops was that most of the invasive species to those regions were emanating from Europe and the Mediterranean Basin, inadvertently or intentionally introduced by man. It was therefore considered as a timely endeavour to organize the next regional meeting in relation to this region. The workshop on 'Biological Invasions in Europe and the Mediterranean Basin' was held in Montpellier, France, 21 to 23 May 1986, thanks to the financial support of SCOPE and of the A.W. Mellon Foundation, and the logistic facilities of the Centre National de la Recherche Scientifique (C.N .R.S.).

This volume contains most of the contributions presented at the Symposium on Vegetation dynamics in grasslands, heathlands, and mediterranean ligneous formations, which took place at the Centre d'Etudes Phytosociologiques et Ecologiques 'Louis Emberger' (locally organized by the Department of General Ecology and the Directory Staff of this institute) at Montpellier. It was organized by the Working Group for Succession research on permanent plots, and the Working Group for Data-processing in phytosociology, both of the International Society for Vegetation Science. The editors of this volume represent both working groups and the organizing institute. They acknowledge the considerable material assistance provided by the Centre National de la Recherche Scientifique, Direction des relations exterieures de l'information, and Programme lnterdisciplinaire de Recherche sur I'Environnement (PIREN); the Conseil general de I'Herault; and the Ministere de I'Environnement et du Cadre de Vie. The Symposium was opened by Prof. M. Godron. The many lectures and poster contributions were organized around five themes. A complete list is added to this volume (Appendix). Abstracts of these contributions were sent in prior to the Symposium and collected by the CEPE in a volume 'Actes du Symposium sur Dynamique de la Vegetation dans les formations herbacees, les landes et les formations mediterraneennes ligneuses'. The 27 ela borated papers accepted for this volume are presented in roughly the same sequence.

This volume is the result of a Symposium, held in October, 1985, to celebrate the Silver Jubilee of the De partment of Plant Ecology of the University of Groningen. The Department of Plant Ecology was founded by Professor Dingeman Bakker and has, since its incep tion, been involved with studies of grasslands, and especially with the effects of human interference on grassland communities. It has been especially involved in an almost unique enterprise to convert areas of grassland from intensive agricultural production to nature reserves. With over-production of most food commodities in the EEC, and increasing interest in various types of 'set aside' schemes, this initiative now seems to be remarkably prescient. The Netherlands have a long history of human manipulation of the environment. Indeed, the Dutch en vironment is probably more man-made than that of any other country. In view of this, and the Laborato ry's interest in managed grasslands, it is not surprising that 'Disturbance in Grasslands' was selected as the topic for the Laboratory's Jubilee Symposium. Although both the Symposium and the resulting vo lume, have a strong Dutch component, the organisers invited a number of contributors from Europe and elsewhere to provide key chapters. The result is a volume which covers many aspects of disturbance in a variety of grasslands. Disturbance is considered at both the community and the population level, and the principles and processes underlying those responses are explored."

This volume is a result of the summary and synthesis of data collected in the Grassland Biome Program, which is part of the American contribution to the International Biological Program (IBP). The purpose of this volume is to present a summary of quantitative ecological investigations of North American grass lands and to present a set of broad comparisons of their characteristics and functions as well as the results of some models and experiments that lead to practical considerations of the management of grasslands. Synthesis is a continuing activity in science. Early in the Grassland Biome Program there was a synthesis of literature data on grasslands, edited by R. L. Dix and R. G. Beidleman (1969). Results of the first year of field data collection under this program were synthesized in a volume edited by N. R. French (1971). Development of the large-scale model constructed to depict the processes and the dynamics of state variables in grassland ecosystems was presented by Innis (1978). Soon to appear will be two volumes integrating studies of American grasslands with IBP studies in other grasslands of the world (Coupland, in press) and the application of systems analysis to understanding grassland function and utilization (Breymeyer and Van Dyne, in press). The present volume presents current results and comparisons of field investigations and experimental studies that were conducted under this program."

This book contains papers on the topics of brought together wetland SCientists from all wetland ecology and management, most of continents and provided an opportunity to exchange valuable information on a variety of which were presented at the 2nd International Wetlands Conference in Trebon, Czechoslovakia aspects on the ecology and management of wetlands. (13-22 June 1984). The conference, hosted by the Hydrobotany Department of the Institute of Botany, was organized by the Czechoslovak This volume contains papers that represent aspects of wetland management. Like most Academy of Sciences and the International ecological topics, the papers clearly Wetlands Working Group of the International Association of Ecology (INTECOL) with demonstrate that the science of wetland management is not evenly developed around the cooperation from the SCOPE (SCientific Committee on Problems of the Environment) world. In some areas, wetlands have not even Working Group on Ecosystem Dynamics in been adequately described and there is little Freshwater Wetlands and Shallow Water Bodies, information about the impacts that man is UNESCO Man and the Biosphere (MAB) having on them. In other areas, information on Program, International Society for Ecological wetland ecology and management has developed Modelling, and the International Society for to the point where regulations and laws provide Limnology (SIL). Partial sponsorship for the some protection against development. It is our conference and these proceedings was provided hope this collection of papers will demonstrate by UNESCO (Contract SCjRPj204. 079.

The urgent need for a sustainable environment has resulted in the increased recognition of the field of landscape ecology amongst policy makers working in the area of nature conservation, restoration and territorial planning. Nonetheless, the question of what is precisely meant by the term landscape ecology'is still unresolved. No doubt, a proper foundation of the discipline must first be cemented. This book develops such a foundation. In doing so it provides all the diverse applications of the discipline with a solid framework and proposes an effective diagnostic methodology to investigate the ecological state and the pathologies of the landscape.

This book is the result of a symposium dedicated to the 25th anniversary of the Delta Institute for Hydrobiological Research in Yerseke, the Netherlands. The primary idea did not come from one of the scientists working in this Institute, but from the second editor. Long before the Institute celebrated itsjubilee on 20-23 October 1982, he expressed his feelings to the other editors, that the time had come for a second European symposium on the ecology of coastal vegetation. The first symposium on this theme was held in Norwich, 12-16 September 1977, being the first meeting of the European Ecological Symposium. He only So the working group Salt waited for a suitable opportunity. Well, the 25th anniversary was a good one. Marsh Ecosystems of the Delta Institute, in close collaboration with him, adopted Dr. Rozema's initiative and set about realizing his idea. An organising committee composed of the editors of this volume, planned the scope of the meeting.

Many aspects of phytogeography have gained loped numerical techniques which allow the com greatly from the recent development of analytical bination of quantitative floristic and vegetational and numerical methods. The new methods have analyses with mapping and causal or evolu opened up new avenues of research, leading to a tionary deductions. The papers selected for the better understanding of the distribution and book show approaches for higher and lower plant evolutionary patterns of species and communities. forms. Several papers dealing with relevant in During the 1987 Botanical Congress in Berlin, formation on vegetation for the respective areas Drs Nimis and Haeupler organized a symposium appear for the first time. The combination of in which examples of present-day phytogeogra new approaches successfully applied to new phic work were discussed. After the symposium problems should be very stimulating to young it was agreed that a proceedings volume should scientists as many papers demonstrate how to be edited by Drs Nimis and Crovello. From the make efficient use of the new developments in lectures presented, those dealing primarily with information science for species-oriented phyto numerical methods were selected for the book. geography. This is the second volume of the T: VS series that While the book does not intend to serve as a deals with new aspects and methods of phyto textbook, it can be viewed as a guide to the geography."

Life originated and evolved in water. Later the The tropical countries where the need to under plants moved out of water, conquered the land and stand the natural ecosystems is far greater because became dominant over it. The evolution through they are under intensive pressure from develop the millennia resulted in enormous complexity of ment from a rapidly growing human population, form, tissue organisation, reproductive mechan have generally devoted much less attention to the isms and specialisation of taxa in different niches. studies of aquatic ecosystems. The Indian subconti At some stage during evolution, some plants devel nent is a well-recognised biogeographic region with oped appropriate morphological and physiological a distinct geological history, climate, soils and adaptations and reverted back to the aquatic and/ biota. It is also distinct in the history of human civilisation and cultures which have a profound bear or semi-aquatic habitat. These plants, perhaps with the exception of a few ing on the natural ecosystems. This book is in with beautiful flowers, have attracted little atten tended to provide the state of our knowledge of the tion from mankind. The fact that humans evolved aquatic and semi-aquatic vegetation in the inland in a tropical forest or savanna environment appears freshwaters of the subcontinent. The book covers responsible for a permanent bias in human atti only the herbaceous vegetation, since there is al tudes towards land and its biota."

Outside Russia very little is known about the terrestrial ecology, vegetation, biogeographical patterns, and biodiversity of the enormously extensive ecosystems of Yakutia, Siberia. These systems are very special in that they function on top of huge layers of permafrost and are exposed to very severe and extreme weather conditions, the range between winter and summer temperatures being more than 100 degrees C. The soils are generally poor, and human use of the vegetation is usually extensive. Main vegetation zones are taiga and tundra, but Yakutia also supports a special land and vegetation form, caused by permafrost, the alas: more or less extensive grasslands around roundish lakes in taiga. All these vegetation types will be described and their ecology and ecophysiological characteristics will be dealt with. Because of the size of Yakutia, covering several climatic zones, and its extreme position on ecological gradients, Yakutia contains very interesting biogeographical patterns, which also will be described. Our analyses are drawn from many years of research in Yakutia and from a vast body of ecological and other literature in Russian publications and in unpublished local reports. The anthropogenic influence on the ecosystems will be dealt with. This includes the main activities of human interference with nature: forestry, extensive reindeer herding, cattle and horse grazing, etc. Also fire and other prominent ecological factors are dealt with. A very important point is also the very high degree of naturalness that is still extant in Yakutia's main vegetation zones.

This book addresses the responses of plants to salinity. Although salinity is a common environmental factor for marine organisms, for the majority of land plants high soil salinity is an environmental constraint that limits growth, productivity, and normal plant functions. Salinity is particularly widespread in arid/semiarid climates where crop production depends on irrigation.

A comprehensive approach is taken in this book. After discussing salinity as an environmental soil factor and its global impact on ecosystems, plant responses are covered from the whole-plant level through metabolic changes to the underlying molecular and genetic mechanisms. In contrast to other books in this subject area, which focus on certain aspects of plant responses to salinity or are conference proceedings, this is the only comprehensive new book on this subject, written by experts in the field. The intended level of readership is graduate students and advanced researchers interested in environmental biology and specifically in the area of mechanisms of environment-plant interactions.

Invasion of non-native plant species, which has a significant impact on the earth's ecosystems, has greatly increased in recent years due to expanding trade and transport among different countries. Understanding the ecological principles underlying the invasive process as well as the characteristics of the invasive plants is crucial for making good management decisions to address this problem. Invasive Plant Ecology includes chapters derived from presentations at conferences such as the World Congress of the International Union of Forestry Research Organizations (IUFRO), as well as contributions from invited renowned authors. The chapters include both original research and syntheses of current knowledge on specific topics. Actions essential for coordinated approaches to curtail plant invasion include increasing awareness of the ecological impacts of alien plants and employing novel control strategies. This book provides a foundation in invasion ecology by examining ecological theories and case studies that explain plant invasions, their impacts, management strategies, and the ecological economics. The chapters describe ecological characteristics, mutualistic associations, microbial communities, and disturbance regimes that affect the spread of invasive plants. The book also covers spatial analysis and predictive modeling of invasive plants. The final chapters offer guidelines for ecological management and restoration of invaded areas and describe the economics of the invasive plant issue. This collection contains case studies from around the world, giving readers a real view of the extent of the invasive species issue along with real-world strategies. With its focus on the ecological aspects of plant invasion, this book provides an important reference for students, scientists, professionals, and policy makers who are involved in the study and management of alien invasive plants and ecosystems.

Ecology is the science of the relationships between living organisms and their envi ronment . . It is concerned with the web of interactions involved in the circulation of matter and the flow of energy that makes possible life on earth, and with the adapta tions of organisms to the conditions under which they survive. Given the multitude of diverse organisms, the plant ecologist focuses upon the plants, investigating the influence of environmental factors on the character of the vegetation and the be havior of the individual plant species. Plant ecophysiology, a discipline within plant ecology, is concerned fundamentally with the physiology of plants as it is modified by fluctuating external influences. The aim of this book is to convey the conceptual framework upon which this discipline is based, to offer insights into the basic mechanisms and interactions within the system "plant and environment," and to present examples of current problems in this rap idly developing area. Among the topics discussed are the vital processes of plants, their metabolism and energy transformations as they are affected by environmental factors, and the ability of these organisms to adapt to such factors. It is assumed that the reader has a background in the fundamentals of plant physiology; the physiological bases of the phenomena of interest will be mentioned only to the extent necessary for an understanding of the ecological relationships."

Deserts are unique ecosystems with their own biotic and abiotic components, and are often rich in renewable natural resources, the appropriate management of which can contribute significantly to the sustainable management of desert regions for the welfare of the people. Yet while there are many books on the flora of the countries fringing the important desert countries of the Mediterranean and Red Seas, there or few books reporting on their ecophysiology and vegetation ecology. This book presents the vegetation types of the African and Asian countries of the Mediterranean and Red Sea coastal regions, and discusses the ecological threats and economic applications of these critical resources. In particular, it examines the relationships between climate and vegetation, and discusses these within the context of desertification, agro-industrial applications, ecotourism and sustainable development. The book will provide a valuable reference for researchers and graduate students involved in plant ecology, biogeography, economic botany and environmental management in the Afro-Asian Mediterranean and Red Sea coastal regions, as well as other desert regions around the world.

Drawing from a decade-long collaboration between Japan and Russia, this important volume presents the first major synthesis of current knowledge on the ecophysiology of the coniferous forests growing on permafrost at high latitudes. It presents ecological data for a region long inaccessible to most scientists, and raises important questions about the global carbon balance as these systems are affected by the changing climate.

Making up around 20% of the entire boreal forests of the northern hemisphere, these permafrost forest ecosystems are subject to particular constraints in terms of temperature, nutrient availability, and root space, creating exceptional ecosystem characteristics not known elsewhere. This authoritative text explores their diversity, structure, dynamics and physiology. It provides a comparison of these forests in relation to boreal forests elsewhere, and concludes with an assessment of the potential responses of this unique biome to climate change.

The book will be invaluable to advanced students and researchers interested in boreal vegetation, forest ecology, silviculture and forest soils, as well as to researchers into climate change and the global carbon balance. "

Note Not long after publication of Orchid Biology, Reviews and Perspectives (OB) volume VII, my co-editor, Dr. Alec M. Pridgeon informed me that the pressure of other duties, especially the editing of Genera Orchidacearum (GO) will make it impossible for him to continue as co-editor and eventually editor ofthe series. Alec is an excellent orchid scientist and editor. I was sorry to that he had to leave OB, but glad that GO will be in his able hands. The first volume of GO attests to his considerable abilities and I wish him much success in the future. Editors of orchid publications are not the most common of species (to use a botanical analogy) and finding a replacement for Alec was not easy. However I was fortunate that Dr. Tiiu Kull agreed to become my co-editor and eventually take over the series. As is obvious from the Contributors section Dr. Kull has extensive experience as both writer and editor. My interactions with her while editing this volume have convinced me she is an excellent choice. Scientifically she brings to OB an appreciation and understanding of northern terrestrial orchids, a group, which has not received as much attention as it deserves. Another addition to OB is Dr. Tim Wing Yam who agreed to become an associate editor. Tim, who holds a position at the Singapore Botanic Gardens, will provide expertise on seed germination, hybridization, tissue culture, species and conservation.

With one volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences. The present volume includes reviews on genetics, cell biology, physiology, comparative morphology, systematics, ecology, and vegetation science.

Eddy VAN DER MAAREL All in all 16 contributions could be collected. The This volume is the second of two volumes covering the symposium 'Advances in vegetation science', which was arrangerr. ent is as follows: held at Nijmegen, The Netherlands, from 15-19 May The contribution by Sjors may serve as a general intro- duction to the types of changes and their names. The 1979. This symposium was organized on behalf of the added paper by Noble and Slatyer provides appropriate Working Group for Data-Processing of the International Society for Vegetation Science. After this group held its facts and views on the mechanisms of vegetation dynamics. final meeting two years earlier it decided to continue its Then a group of contributions follows in which data on species behaviour, plant demography and diversity during activities, but in a wider scope. Most members of the succession are discussed. This includes Faliriski's study on Group felt that the original aim, i. e. the introduction of data-processing and multivariate methods for use in the sex structure and dynamics of pioneer woody species, a systematic description of plant communities, was more or fynbos diversity study by Campbell & van der Meulen and less fulfilled. The book Data-Processing in Phytosociology, studies on Mediterranean shrubs and trees in post-fire and postcultural developments by Trabaud and Lepart, Hous- largely based on papers in Vegetatio, edited by E. van der Maarel, L. Orl6ci & S. Pignatti, and to be published by sard, Escarre and Romane, and Debussche and Romane.

Mongolia is an expansive land-locked country, tilted by tectonic forces to the North, that experiences extremes of continental climate. Moisture-carrying wind currents are scarce so that the land has extended highs and lows in its environment. Culturally the people are mostly nomadic, having been sustained for centuries by an economy based on domestic livestock grazing. There is a saying that, As the noses go, so goes Mongolia', referring to the domesticated grazing noses of sheep, goats, camels, yaks or horses, and wild ungulates such as gazelles. The vast fenceless steppes of Mongolia furnish the vegetation for grazing. With such extremes in climate it is clear that the vegetation must be resilient and dynamic to cope with the dictates of its extremely harsh environments. Pollen profiles from lakes, plant macrofossils and other data over the last 15,000 years show the dynamic nature of Mongolian vegetation. Currently Mongolian society is experiencing much human-driven economic development which increases pressure on its vegetation. The Great Khural Laws of 1995 forcefully addressed such environmental concerns with the expanded establishment of National Reserves and Parks. But continued effort and vigilance must be expended to insure that Mongolian society will continue to be sustained by its vegetation. This book highlights work such as conserving and restoring plant diversity in various ecosystems and makes recommendations for sustaining the vegetation basis of the nomadic Mongolian society.