Plants, fungi, and viruses were among the first biological objects studied with an electron microscope. One of the two first instruments built by Siemens was used by Helmut Ruska, a brother of Ernst Ruska, the pioneer in constructing electron microscopes. H. Ruska published numerous papers on different biological objects in 1939. In one of these, the pictures by G. A. Kausche, E. Pfankuch, and H. Ruska of tobacco mosaic virus opened a new age in microscopy. The main problem was then as it still is today, to obtain an appropriate preparation of the specimen for observation in the electron microscope. Beam damage and specimen thickness were the first obstacles to be met. L. Marton in Brussels not only built his own instrument, but also made considerable progress in specimen preparation by introducing the impregnation of samples with heavy metals to obtain useful contrast. His pictures of the bird nest orchid root impregnated with osmium were revolutionary when published in 1934. It is not the place here to recall the different techniques which were developed in the subsequent years to attain the modern knowledge on the fine structure of plant cells and of different plant pathogens. The tremendous progress obtained with tobacco mosaic virus is reflected in the chapter by M. Wurtz on the fine structure of viruses in this Volume. New cytochemical and immunological techniques considerably surpass the morphological information obtained from the pathogens, especially at the host-parasite interface.

Der vorliegende 6. Band konnte die Oberschrift "Pflanzenschutzforschung auf neuen Wegen" tragen. Trotz der verbreiteten, meist aufmangelndem Informations- stand beruhenden Voreingenommenheit gegen den chemischen Pflanzenschutz, nimmt dessen Bedeutung sHindig zu. Das beruht auf der Notwendigkeit einer sicheren und rationellen landwirtschaftlichen Produktionssteigerung, die durch das rapide Wachstum der WeItbevolkerung erzwungen wird. Zwar ist die land- wirtschaftliche Produktivitat auch in einigen Entwicklungslandern wahrend der letzten 15 Jahre merklich gestiegen, sie haIt aber vielfach mit der Vermehrung der Bevolkerung nicht Schritt. Der Pflanzenschutz ist nicht einseitig auf bestimmte Methoden festgelegt, sondern bedient sich unvoreingenommen aller wirtschaftlich und okologisch vertretbaren Wege und Verfahren. Hierbei wird auch die Forschung nach neuen Wirkstoffen und chemischen Verfahren auf sehr breiter Grundlage weiterbetrieben, wenn auch unter merklicher Steigerung der Forschungskosten. Jeder neue Wirk- stoff muB einen Fortschritt gegeniiber einem eingefUhrten Handelsprodukt dar- stellen. Wichtige Kriterien sind hierbei neben der Wirksamkeit die Umwelt- vertraglichkeit, unter anderem giinstigere toxikologische Eigenschaften, Sicher- heit in der Anwendung und Wirtschaftlichkeit. Wie schon in Band 3 (Beitrag Haug) dargestelIt, sind gerade auch diejenigen Kosten fUr Forschung und Ent- wick lung, die der langfristigen Unbedenklichkeit und Sicherheit der Produkte dienen, iiberproportional gestiegen.

The public's attitude toward air pollution in the United States evolved substantially during the 1960s. One of the results of the nation's emerging environmental ethic was the creation of the U. S. Environmental Protection Agency (EPA) in December of 1970. Prior to this time, research was focused on the impacts of air pollution on human health and welfare and was largely conducted by several federal research agencies, which included the Department of Health, Education, and Welfare; the National Oceanic and Atmospheric Administration; and the U. S. Department of Agricul ture. After the creation of the EPA, much of this work was consolidated in one regulatory agency, which resulted in periodic evaluations of the various effects of atmospheric pollution on human health, materials, agriculture, and forest ecosystems. At the same time that environmental interest was growing in the United States, concern increased in the European scientific community and public over the ecological impacts of acidic deposition. As the magnitude of the damage to European lakes and streams and the widespread decline in Norway spruce and silver fir was reported, concern that similar problems were occurring in the United States increased substantially. This concern was heightened by press reports of high elevation spruce-fir forest declines in the Adirondack and Appalachian Mountains and the decline and death of sugar maples in the northeastern United States and Canada.

This is a stimulating tale of the interplay of observation, experimentation, working hypotheses, tentative conclusions, niggling and weightier doubts and great aspirations, on the part of some score of students, on varied ecological and other aspects of the regime and role of fire in relevant biomes and ecosystem- mainly in South Africa - and on other pertinent features of fire ecology. The impressive contents is a tribute to conveners and authors alike. One can expect a profound range and depth ofinvestigation and interpretation, a closeknit fabric of knowledge, delicately interwoven with wisdom, an exposition and quintessence of information. Admipable is the collective vision responsible for selecting appropriate topics: the wide sweeps of the brush picturing the nature of the biomes; ably describing the fire regimes - whether in grassland, savanna, fynbos or forest; skillfully defining the effects of such regimes - according to ecosystem - upon aerial and edaphic factors of the habitat, upon constituent biota, individually, specifically and as a biotic community; elucidating the basic implications in the structure and dynamics of the plant aspect of that community ... and unravelling to some degree the tangled knot of the conservation and dissipation of moisture and nutrients. Moreover, gratitude is owed for efforts exerted to understand the interplay of fire and faunal behaviour and dynamics as well as composition, together with the principle of adaptive responses of organisms of diverse kinds.

The importance of irrigation in the world's agriculture is rapidly increasing. Although it is practised on a large scale mainly in arid and semi-arid zones, supplementary irrigation is becoming popular in semi-humid regions as well. The record of irrigation speaks for itself in terms of increased crop production. However, the question remains as to how permanent the achievement may be. Judging from history, it seems that irrigation eventually failed in many regions because the knowledge and technology available to society at the time were incapable of coping with the problems created. Undoubtedly soil salinity is the most prevalent and widespread problem limiting crop productivity in irrigated agriculture. It has, therefore, attracted the attention of the scientific community since the advent of modern agronomic research. Through the past six to seven decades a considerable body of information has been accumulated, which has promoted the understanding of the principles involved and helped to develop the technology for coping with the problems. Our present knowledge, if judiciously applied, is adequate for coping with many of the salinity problems resulting from mismanagement of irrigation and drainage. But for this knowledge to be used, it has to be generally known and understood and be re-examined from time to time.

Metal Speciation in the Environment is a multidiscipliary treatment of the occurrence, mobility and detection of metal compounds within different environments as well as their interaction with life. Special emphasis is given to the complexation of metals, to the state of the art of trace analytical methodology available for metal speciation (including atomic absorption spectrometry, plasma emission and mass spectrometry, neutron activation analysis, electrochemical methods, chemical sen- soring, a.o.), and environmental chemistry of elements such as the actinides and heavy metals (e.g. chromium, arsenic, tin, and copper).

The information presented in this book is the result of combined research efforts of scientists at the University of Alaska, Fairbanks, the Institute of Northern Forestry, USDA Forest Service, and the Systems Ecology Research Group, San Diego State University. The objective of the volume is to present a synthetic overview of structure and function of taiga forest ecosystems in interior Alaska. The data base for this work has appeared in earlier published articles including the special issue of the Canadian Journal of Forest Research Volume 13:5 (1983). Stimulus for this book was a conference held in Fairbanks from June 10-14, 1983. The papers presented at the conference were fore runners of the chapters in this book. We invited 19 scientists from North America and England to critique our research and synthesis efforts. Six of these people were asked to write introductory chapters for each section of the book. Formal presentation sessions, combined with field trips to research sites, introduced the invitees to the primary and secondary successional ecosystems with which we were dealing. A major wildfire, only 24 km from the University campus, was contained the week prior to the conference and one field trip provided graphic evidence of fire impact in subarctic forests. The conference conveners regretted that it was not possible to host a similar meeting during synthesis efforts in mid-January."

The Advanced Series in Agricultural Sciences is designed to ftll a long-felt need for advanced educational and technological books in the agricultural sciences. These texts, intended primarily for students of agriculture, should also provide up-to-date technical background reading for the many agricultural workers in extension services, educational systems, or international bodies. The editors of Advanced Series in Agricultural Sciences will select key subjects relating to the agricultural environment, agricultural physics and chemistry, soil science, plant sciences, animal sciences, food technology, and agricultural engineering for a critical and synthetic appraisal. An initial theoretical presentation will be used by authors of individual volumes in the series to develop a technical approach-including examples and practical solutions- to each subject. In addressing the advanced undergraduate and early graduate student of agriculture, selected authors will present the latest information, leavened with the lessons learned from their own experience, on precise and well-defined topics. Such books that widen the horizons of the student of agriculture can serve, too, as useful reference sources for the young specialist in the early years of his career. Many specialists who are involved in teaching agricultural science are isolated from universities and research institutions. This series will bring them up-to-date scientific information, thus keeping them in touch with progress. The basic objective of Advanced Series in Agricultural Sciences is to effect a structural integration of the theoretic and technical approaches to agriculture.

This is the second of the set of three volumes in the Encyclopedia of Plant Physiology, New Series, that will cover the area of the hormonal regulation of plant growth and development. The overall plan for the set assumes that this area of plant physiology is sufficiently mature for a review of current knowl edge to be organized in terms of unifying principles and processes. Reviews in the past have generally treated each class of hormone individually, but this set of volumes is subdivided according to the properties common to all classes. Such an organization permits the examination of the hypothesis that differing classes of hormones, acting according to common principles, are determinants of processes and phases in plant development. Also in keeping with this theme, a plant hormone is defined as a compound with the properties held in common by the native members of the recognized classes of hormone. Current knowledge of the hormonal regulation of plant development is grouped so that the three volumes consider advancing levels of organizational complexity, viz: molecular and subcellular; cells, tissues, organs, and the plant as an organized whole; and the plant in relation to its environment."

The world needs for food and fiber continue to increase. Population growth in the developing countries peaked at 2. 4 percent a year in 1965, and has fallen to about 2. 1 percent. However, in many developing countries almost half the people are under 15 years of age, poised to enter their productive and reproductive years. The challenges to produce enough food for this growing population will remain great. Even more challenging is growing the food in the areas of greatest need. Presently the world has great surpluses of food and fiber in some areas while there are devastating deficiencies in other areas. Economic conditions and the lack of suitable infrastructure for distribution all too often limit the alleviation of hunger even when there are adequate supplies, sometimes even within the country itself. World hunger can only be solved in the long run by increasing crop production in the areas where the population is growing most rapidly. This will require increased efforts of both the developed and developing countries. Much of the technology that is so successful for crop production in the developed countries cannot be utilized directly in the developing countries. Many of the principles, however, can and must be adapted to the conditions, both physical and economic, of the developing countries.

Rhizobia are bacteria which inhabit the roots of plants in the pea family and "fix" atmospheric nitrogen for plant growth. They are thus of enormous economic importance internationally and the subject of intense research interest. Handbook for Rhizobia is a monumental book of practical methods for working with these bacteria and their plant hosts. Topics include the general microbiological properties of rhizobia and their identification, their potential as symbionts, methods for inoculating rhizobia onto plants, and molecular genetics methods for Rhizobium in the laboratory. The book will be invaluable to Rhizobium scientists, soil microbiologists, field and laboratory researchers at agricultural research centers, agronomists, and crop scientists.

In Recognition of the Forgotten Generation D. L. MULCAHyl Pollen was long believed to serve primarily a single function, that of delivering male gametes to the egge A secondary and generally overlooked value of pollen is that it serves to block the transmission of many defective alleles and gene combinations into the next generation. This latter function comes about simply because pollen tubes carrying defective haploid genotypes frequently fail to complete growth through the entire length of the style. However, the beneficial consequences of this pollen selection are diluted by the fact that the same deleterious genotypes are often transmitted through the egg at strictly mendelian frequencies (Khush, 1973). Gene expression in the pollen might thus at least appear to be a phenomenon of trivial consequence. Indeed, Heslop-Harrison (1979) rightly termed the gametophytic portion of the angiosperm life cycle, the "forgotten generation." This neglect, however, came about despite subtle but constant indications that pollen is the site of intense gene activity and selection. For example, Mok and Peloquin (1975) demonstrated that relatively heterozygous diploid pollen shows heterotic characteristics whereas relatively homozygous diploid pOllen does not. This was proof positive that genes are expressed (that is, transcribed and translated) in the pollen. 1 Department of Botany, University of Massachusetts Amherst, MA 01003, USA viii However, the implications for pollen biology of even this recent and well known study were not widely recognized.

Chemistry of Plant Protection continues the handbook "Chemie der Pflanzenschutz- und Schadlingsbekampfungsmittel", edited by R. Wegler. Volumes 4 and 5 of the series provide the first complete and in depth overview of synthetic pyrethroid insecticides . Volume 5 presents a detailed survey of the numerous synthetic methods (270 reaction schemes) and of stereochemical aspects of trade products, and a compilation of almost every patent on pyrethroids (2700 references evaluated).

Second in the series, High-Tech and Micropropagation, this work covers the micropropagation of trees and fruit-bearing plants, such as poplar, birches, larch, American sweetgum, black locust, "Sorbus," sandalwood, "Quercus," cedar, Persian walnut, date palm, cocoa, "Citrus," olive, apple, pear, peach, plum, cherry, papaya, pineapple, kiwi, Japanese persimmon, grapevine, strawberry, and raspberry. The importance and distribution of conventional propagation and in vitro studies on individual species are discussed. In particular detail, the transfer of in vitro plants to the greenhouse or the field, and the prospects of commercial exploitation are examined. The book will be of use to advanced students, research workers and teachers in horticulture, forestry and plant biotechnology in general, and also to individuals interested in industrial micropropagation.

No matter what forests are used for, forest managers have to deal with interactions between individual trees and between trees and other forest organisms. To understand these interactions, long-term monitoring of spontaneous forest development is necessary. A complete monitoring system has been developed including a computer package for analysis of long-term observation of forest dynamics. The system's name, "SILVI-STAR," is an acronym of SILVIgenesis and Single-tree Three-dimensional Architecture. A method of nested plot data collection on forest architecture and plant species composition has been developed out for monitoring purposes.

Since the late 1960s the Indonesian state of East Kalimantan has witnessed a marked increase in the impact of human activities chiefly commercial logging and agricultural exploitation. Located on the island of Borneo, East Kalimantan also was subjected to prolonged droughts and extensive wildfires in 1982-83 and 1997-98 that were linked to the El Nino-Southern Oscillation (ENSO) phenomenon. The changes in the rainforest ecosystem in East Kalimantan during this 15-year cycle of severe ENSO events are the subject of this book. With an eye toward development of rehabilitation techniques for sustainable forest management, the authors examine possible interactive effects of drought, fire, and human impacts on the flora and fauna of the area.

Comprising about one hundred plates this atlas documents and describes the processes concerning the sexual reproduction in higher plants. It is dividedinto three parts: - Anther Development - Pistil Development - Progamic Phase and Fertilization. The scanning, transmission electron and light micrographs are all of immaculate quality and - for the viewer's orientation - almost each plate is complemented by a scheme showing a larger area of the plant indicating the site of the section. Together with instructive texts, the often striking images provide a valuable introduction into plant reproductive cell structures for researchers and advanced students of genetics, plantbreeding and cell biology.

As a result of the green revolution, the use of yield-increasing inputs such as fer tilizer and pesticides became a matter of course in irrigated rice farming in Southeast Asia. Pesticides were applied liberally, both as a guarantee against crop failure and as a means of fully utilizing the existing yield potential of the crops. However, since outbreaks of pests, such as the brown planthopper (BPH) or the tungro virus, continued to occur despite the application of chemicals, a change of approach began to take place. It is now being realized more and more in Southeast Asia that crop protection problems cannot be resolved solely by the application of chemicals. In the past several years, increasing efforts have there fore been made to introduce, as a first step, supervised crop protection, leading gradually to integrated pest management (Kranz, 1982). Although the crop protection problems naturally differ in the different devel oping countries in Southeast Asia, the economic situation prevailing in these countries can nevertheless be regarded as an important common determinant: pesticide imports use up scarce foreign currency and thus compete with other imports essential to development. For the individual rice farmer, the problem is basically the same: his cash funds are limited and he must carefully weigh whether to use them for purchas ing pesticides, fertilizer or certified seed. In view of this constraint, it is becom ing necessary to abandon the purely prophylactic, routine calendar spraying and instead, employ critically timed and need-based pesticide applications."

This book has a similar subject content to the author's previous Flow in Wood but with substantial updating due to the abundance of research in the wood science field since 1971. Several different concepts have been introduced, particularly in regard to wood-moisture relation ships. The role of water potential in the equilibria between wood and its humid and moist environments is considered. Two theories are introduced to explain the nonisothermal transport of bound water in the steady and unsteady states. As in the former text, the wood-. structure relationship is emphasized . . The author is especially grateful to Dr. C. Skaar for his careful and critical review of much of the manuscript and for the productive dis cussions of many of the concepts. Dr. T. E. Timell, the series editor, rendered major assistance in the preparation of Chap. 2 and in his editing of the manuscript. The author wishes to thank Dr. W. A. Cote, Mr. A. C. Day, and Mr. J. J. McKeon for providing electron micro graphs, Mr. G. A. Snyder for his photography of much of the art work, Dr. C. H. de Zeeuw for his advice in the field of wood anatomy, and Ms. Mary M. Siau for her careful rendition of the art work. Apprecia tion is extended to Miss Judy A. Barton and Mrs. Stephanie V. Micale for their work in typing and checking the manuscript. Mr. J. A."

This book is directed at foresters who work, or have an interest, in the developing world, and at development analysts and theorists who are concerned with the forestry sector. Most readers will be aware that in recent years, some fundamental changes in thinking about the development process in very poor countries have occurred. At one level, the underdevelopment problem has been explained as a lack of absorptive capacity, or implementation ability in very poor countries. However, it now seems that these are only symptoms of a more profound ailment in the whole economic structural and philosophical approach to development. The idea that poor countries could transform their economies through an accelerated process of industrialisation has proved largely incorrect, or at least highly premature. Within the rural sector, emphasis on productivity and aggregate income growth have been shown to have had little effect or, worse still, negative effects, on the burgeoning group of poor and landless rural dwellers.

Succession-nothing in plant, community, or ecosystem ecology has been so elaborated by terminology, so much reviewed, and yet so much the center of controversy. In a general sense, every ecologist uses the concept in teaching and research, but no two ecologists seem to have a unified concept of the details of succession. The word was used by Thoreau to describe, from a naturalist's point of view, the general changes observed during the transition of an old field to a forest. As data accumulated, a lengthy taxonomy of succession developed around early twentieth century ecologists such as Cooper, Clements, and Gleason. Now, nearer the end of the century, and after much discussion concerning the nature of vegetation communities, where do ecologists stand with respect to knowledge of ecological succession? The intent of this book is not to rehash classic philosophies of succession that have emerged through the past several decades of study, but to provide a forum for ecologists to present their current research and present-day interpretation of data. To this end, we brought together a group of scientists currently studying terrestrial plant succession, who represent research experience in a broad spectrum of different ecosystem types. The results of that meeting led to this book, which presents to the reader a unique summary of contemporary research on forest succession.

This book brings together research into the process of stream acidification and its impact on Welsh surface waters, carried out over the past decade or so. It is perhaps surprising that not until the 1980's was clear evidence of stream acidification assembled. In Wales, concerns over pollution had focused water quality sampling principally on the areas of traditional heavy industry and large urban popula tions served by inadequate sewerage systems and sewage disposal arrange ments. Mistakenly, it had been assumed that, with its prevailing westerly winds, Wales would receive precipitation substantially unpolluted by the industrial and urban emissions from Britain and mainland Europe. Assurance of the high quality of Welsh upland streams, the traditional nursery ground of salmonids, was eroded particularly by studies in the vicinity of Llyn Brianne reservoir in the catchment of the River Tywi of Central Wales. These demonstrated a clear correspondence between the biological quality and fisheries of streams in the catchment and aspects of stream chemistry, par ticularly pH, aluminium and calcium on the one hand, and catchment land use on the other. It is salutary to record that the first signals were of an inexplicable failure of the runs of migratory salmonids into the upper catchment, occupied by the Llyn Brianne reservoir and its influent streams, and the failure to restore the fishery by re-stocking with eggs and fry. Only then did the significance of the recent decline in some other upland lake and reservoir fisheries in Wales become apparent.

It is enough to work on the assumption that all of the details matter in the end, in some unknown but vital way. Edward O. Wilson, Biophilia Advances in knowledge of northern ecology have been so rapid that to undertake a synthesis of all the literature now available would be a major enterprise, perhaps even a life's work, and so it must be considered permissible to fill in a few gaps, follow one's own inclinations, leaving comprehensive syntheses to those willing to undertake them. This is the rubric under which I have written, reporting some of the more interesting data I and others have obtained over the years, often diverging into discussions of plants, soils, climate, and faunal relationships which have perhaps not previously been dealt with extensively, or at least in quite the same way. This is purely intentional, since I find it difficult to summon up the needed enthusiasm, at this late hour, to write on topics which unfortunately for me have little attraction. I have thus written for the pleasure derived from depicting, perhaps at times as something of an impressionist, a fascinating biotic region, a captivating land, a collection of interesting ecological problems, environmental relationships to be discerned in part, perhaps understood to some small degree, perhaps one day to be modeled mathematically. As Leo Szilard once wrote: ': . . to be able to say even this much might be of some value" (Szilard, 1960).

Roger C. Dahlman Environmental Sciences Division U.S. Department of Energy Washington, D.C. The potential for humans to alter Earth's atmosphere has been recognized since the end of the 19th century when Arrhenius estimated that a doubling of atmospheric carbon dioxide could alter the atmospheric radiation balance and raise average global temperature. Today, atmospheric CO concentrations play an important part in the 2 climate-change debate. Sources and sinks of CO associated with land use can be 2 significant determinants of the rate and magnitude of atmospheric CO change. 2 Combustion of fossil fuels and the deforestation associated with land-use change both contribute CO to the atmosphere; in contrast, biological processes on land create 2 potential sinks for the excess CO . Thus, land-use change and associated biological 2 processes become important elements in assessments of future atmospheric CO 2 increase; land-cover properties also affect the Earth's albedo, which is a climate feedback.