Soil degradation is clearly one of the most pressing problems facing man kind. A continuation of soil degradation will eventually lead to a loss in crop productivity even though fertilizers and other inputs often result in increased yields in the short term. Soil degradation also leads to environ mental pollution. A decrease in soil quality invariably leads to a decrease in water quality, and often in air quality. While there is a clear consensus that soil degradation is a major problem, the literature on this subject leaves numerous baffling questions. If statis tics on land degradation are correct, there is a definite cause for concern, and present a mammoth challenge for agricultural scientists. There are those that say the scientific community has over dramatized this issue, and created a credibility problem. Consequently; Volume 11 of Advances in Soil Science was organized by Dr. Rattan Lal who is recognized as a lead ing authority on the subject. The objective of Volume 11 was to assess the types and processes of soil degradation and establish some of the major cause-effect relationships. Volume II documented the seriousness of soil degradation in many parts of the world. Therefore, it seemed immediately important to devote a volume to the principles and technologies for restor ing degraded soils to a productive status. While the land resources are limited, world population is rapidly increasing, particularly in developing countries. Dr."

This book had its genesIs In the frustrations of the editors in locating authoritative, up-to-date material for an interdisciplinary graduate course in mammary gland biology, lactation, and breast-feeding. As we turned to the original literature several reasons for the dearth of usable material became clear: (1) In the areas of mammary gland biology and physiology, particularly as they relate to the human, reviews simply have not kept up with current research, which has in the last two decades provided tremendous insight into the mechanisms of milk secretion and its control. (2) The lack of interest in human milk as infant food inhibited researchers until very recently from investigating human lactation. (3) Much of the relevant clinical information remains anecdotal with little scientific basis. In this book we have tried to present the fundamentals of mammary gland physiology at the organismic and cellular levels in a form readily understood by physicians, scientists, and other professionals. This basic information is accompanied by authoritative reviews of the nutritional and immunological properties of human milk and by clinically relevant chapters designed to help health care professionals deal with the medical problems of the breast-feeding mother and her infant. We have strived in these chapters for up-to-date, authoritative, but readable accounts. In so far as possible we have avoided areas where much of our understanding rests on speculation. In the clinical domain this was not always possible because of a lack of solid, scientific information about breast-feeding.

These Proceedings evolved from the OECD Co-operative Research Programme workshop on "Potential ecological impact of transgenic plants expressing viral sequencies," held at the Agricultural Biotechnology Center in Godollo, Hungary on 24-26 April 1997. The OECD Co-operative Research Programme At the Directorate for Agrieulture of the Organisation for Economie Co-operation and Development (OECD) a co-operative research programme for "Biological Resource Management" has existed since 1990. It foeuses on work in four specific topie areas, one of whieh is "Ecology and utilisation of new organisms" (Theme 3). The activities promoted by this programme are post-doctoral fellowships (announced annually), and the organisation of expert workshops (1-2 workshops per Theme per year). The 26 OECD member countries participating in this programme are: Australia, Austria, Belgium, Canada, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, ltaly, Korea, Japan, the NetherIands, New Zealand, Norway, Poland, Portugal, Spain, Sweden, SwitzerIand, Turkey, the UK, and the USA."

We have the pleasure to present to you the proceedings of the XIVth congress of the "Association pour l'Etude Taxonomique de la Flore d'Afrique Tropicale" (AETFAT). The XIVth AETFAT congress was held from 22 to 27 August 1994, at the Wageningen International Conference Centre in Wageningen, The Netherlands. The congress was attended by 215 participants, 104 of which came from 28 African countries. During the congress 46 papers and more than 100 posters were presented, the texts of most of which are presented in these Proceedings. The expenses of the congress were covered by grants from the Wageningen Agri- cultural University, the Royal Netherlands Academy of Sciences, and others; see page XVI for a complete list. Funds for the participation of 55 members from Africa came from a number of sponsors, in particular from the Directorate General for International Cooperation, the Technical Centre for Agricultural and Rural Co-operation, the Tropenbos Foundation, and Shell Nederland. We express our sincerest thanks to all contributors. The convenors who organized the symposia, and edited the papers afterwards, are gratefully acknowledged. The editors also acknowledge the valuable help of J.J. Bos and A.J.M. Leeuwenberg, both with preparations in the Organizing Committee, as well as with ftnal editing. The printing was undertaken by Kluwer Academic Publish- ers, in collaboration with A.C. Plaizier.

''A wealth of information...these two volumes will be immensely valuable to anyone having to deal with this difficult group of compounds.'' ---Biochemical Systematics and Ecology, from a review of Saponins Used in Traditional and Modern Medicine and Saponins Used in Food and Agriculture ''A valuable contribution to the literature.'' ---The Quarterly Review of Biology, December 1997

In recent years many of the conventional methods of insect control by broad spectrum synthetic chemicals have come under scrutiny because of their unde sirable effects on human health and the environment. In addition, some classes of pesticide chemistry, which generated resistance problems and severely affected the environment, are no longer used. It is against this background that the authors of this book present up-to-date findings-relating to biochemical sites that can serve as targets for developing insecticides with selective prop erties, and as the basis for the elucidation of resistance mechanisms and countermeasures. The book consists of eight chapters relating to biochemical targets for insec ticide action and seven chapters relating to biochemical modes of resistance and countermeasures. The authors of the chapters are world leaders in pesti cide chemistry, biochemical modes of action and mechanisms of resistance. Biochemical sites such as chitin formation, juvenile hormone and ecdysone receptors, acetylcholine and GABA receptors, ion channels, and neuropeptides are potential targets for insecticide action. The progress made in recent years in molecular biology (presented in depth in this volume) has led to the iden tification of genes that confer mechanisms of resistance, such as increased detoxification, decreased penetration and insensitive target sites. A combina tion of factors can lead to potentiation of the resistance level. Classifications of these mechanisms are termed gene amplification, changes in structural genes, and modification of gene expression.

Over the last decade there has been tremendous progress in the genetic transformation of plants, which has now become an established tool for the insertion of specific genes. Work has been conducted on more than 200 plant species of trees, cereals, legumes and oilseed crops, fruits and vegetables, medicinal, aromatic and ornamental plants. Transgenic plants have been field-tested in a number of countries, and some release_d to the farmers, and patented. Taking the above-mentioned points into consideration, it appeared nec- essary to review the literature and state of the art on genetic transformation of plants. Thus 120 chapters contributed by experts from 30 countries (USA, Russia, Canada, France, Germany, England, The Netherlands, Belgium, Switzerland, Italy, Spain, Bulgaria, Yugoslavia, Denmark, Poland, Finland, Aus- tralia, New Zealand, South Africa, China, Japan, Korea, Singapore, Indonesia, India, Israel, Mexico, Cuba, etc. ) are compiled in a series composed of the fol- lowing five books: 1. Transgenic Trees comprises 22 chapters on forest, fruit, and ornamental species such as Allocasuarina verticillata, Casuarina glauca, Cerasus vul- garis, Citrus spp. , Coffea species, Diospyros kaki, Eucalyptus spp. , Fagara zanthoxyloides, Larix spp. , Lawsonia inermis, Malus x domestica, Picea mariana, Pinus palustris, Pinus radiata, Poncirus trifoliata, Populus spp. , Prunus species Rhododendron, Solanum mauritianum, Robinia pseudoa- cacia, Taxus spp. , and Verticordia grandis. 2.

In the early 1980s, forest decline became a matter of public and scientific concern when forest stands with Norway spruce (Picea abies [L. ] Karst. ) showed evident damage on a large geographical scale throughout Europe. The causes of the observed symptoms could not be elucidated on the basis of the state of knowledge at that time. Therefore, several research projects were launched both in Germany and in some other countries in order to identify the relevant pathogenic factors. In 1985, the Federal Ministry for Research and Technology decided to include the site "Postturm", forest district Farchau/Ratzeburg, in the spon sorship of the research on forest decline as a site typical for lowlands and a sphere of anthropogenic urban influence. The investigation area is situated about 40 krn east-northeast of the city of Hamburg. Since spruce trees in particular showed severe decline, emphasis was laid on this species. The programme started in 1986 and extended to 1992, with some activities con tinuing beyond this time. Working groups from 13 institutions took part in the overall project.

First attempts to isolate plant genes were for those genes that are abun dantly expressed in a particular plant organ at a specific stage of devel opment. However, many important gene products are produced in a very minute quantity and in specialized cell types. Such genes can now be isolated using a variety of approaches, some of which are described in this volume. The rapid progress during the last decade in regeneration of a number of crop plants and the availability of molecular tools to introduce foreign genes in plants is allowing the engineering of specific traits of agri cultural importance. These genes must, however, be regulated in a spatial and temporal manner in order to have desired effects on plant devel opment and productivity. The habitat of plants necessitate adaptive responses with respect to the environmental changes. Starting from germination of the seed, the plant begins to sense environmental cues such as moisture, light, temperature and the presence of pathogens, and begins to respond to them. Little is known about various signal transduction pathways that lead to biochemical and morphogenetic responses, in particular, transition from vegetative to reproductive phase. With the availability of tools to generate specific mutations via transposon tagging, identification and isolation of genes affecting these processes may be facilitated. Transfer of these genes into heterologous environments will allow understanding of the complex processes that control plant development."

Volume 10 of Advances in Disease Vector Research consists of seven chapters on vectors that affect human or animal health and six chapters on plant pathogens and their vectors. In Chapter 1, Yasuo Chinzei and DeMar Taylor discuss hormonal regulation of vitellogenesis in ticks. Many blood sucking insects and ticks transmit pathogens by engorgement, which induces vitellogenesis and oviposition in adult animals. To investigate the pathogen transmission mechanism in vector animals, information on the host physiological and endocrinological conditions after engorgement is useful and important because pathogen development or proliferation occurs in the vector hosts at the same time as the host reproduction. Chinzei and Taylor have shown that in ticks, juvenile hormone (JH) is not involved in the endocrinological processes inducing vitellogenin biosynthesis. Synganglion (tick brain) factor(s) (vitellogenesis inducing factor, VIF) is more important to initiate vitellogenesis after engorgement, and ecdysteroids are also related to induction of vitellogenin synthesis. In their chapter, based mainly on their own experimental data, the authors discuss the characterization of main yolk protein, vitellogenin (Vg) , biosynthesis and processing in the fat body, and hormonal regulation of Vg synthesis in tick systems, including ixodid and argasid ticks.

Ecological Land Classification (ELC) refers to the description of land resources at a range of spatial resolutions (i.e. global to local) and for a range of purposes or values. The emerging science of ELC is in fact a very carefully integrated blend of vegetation and earth sciences, climatology, cartography and ecology with a range of new technologies and methodologies including computer-based geographic information systems, remote sensing and simulation modelling. This publication defines the current state-of-the-art' of ELC. It provides particular insight into the role of ELC in current and future forest resource planning and management, and emphasizes its application and usefulness at various spatial scales, for a variety of geographic locations, and under a range of management scenarios/constraints. The book is an invaluable and substantial reference source about the current trends in ELC and will be of particular value to ecologists, foresters, geographers, resource managers, wildlife biologists, GIS and remote sensing specialists, educators and students.

Recently, there has been tremendous progress in the genetic transformation of agricultural crops, and plants resistant to insects, herbicides, and diseases have been produced, field tested and patented. "Transgenic Crops I" compiles this information on cereals, grasses, legumes, and oilseed crops. It is divided into two sections: I. Cereals and Grasses: wheat, rice, maize, barley, sorghum, pearl millet, triticale, "Agrostis" spp., "Cenchrus" "ciliaris," "Dactylis glomerata," "Festuca" "arundinacea," "Lolium" spp., and sugarcane. II. Legumes and Oilseed Crops: "Arachis hypogaea," "Brassica juncea," "Brassica" " napus," " Cicer arietinum," " Glycine" "max," " Gossypium" "hirsutum," " Helianthus annuus," "Lens culinaris," "Linum usitatissimum," "Sinapis alba," "Trifolium," and "Vicia" "narbonensis."
This book is of special interest to advanced students, teachers, and research workers in the field of plant breeding, genetics, molecular biology, plant tissue culture, and plant biotechnology in general.

The chapters in this book represent detailed versions of papers presented at the Symposium on Viral Genes and Plant Pathogenesis held at Lexington, Kentucky on October 16 and 17, 1989. In selecting topics and authors, we attempted to have represented a spectrum of systems which are at the forefront of research on plant virus genes and gene products, particularly as they relate to plant disease. The book also contains pertinent discussion of the papers presented at the symposium, as well as summaries, observations and projections of future research directions prepared by the session chairmen. We wish to express our appreciation to Dr. D. L. Davis, of the RI. Reynolds Tobacco Company for suggesting the organization of the Symposium and the publication of the proceedings, and to the R 1. Reynolds Tobacco Company for the financial support which made the symposium possible. We also wish to thank those of our colleagues in the Department of Plant Pathology, University of Kentucky, who very ably and in many ways contributed to the organization and conduct of the conference. Thomas P. Pirone lohnG. Shaw v Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi INDUCTION OF HOST GENES BY THE HYPERSENSITIVE RESPONSE OF TOBACCO TO VIRUS INFECTION J. F. Bol, C. M. A. van Rossum, Bl. C. Cornelissen and H. J. M. Linthorst . . . . . . . . . . . . . . . . . l COAT PROTEIN MEDIATED RESISTANCE IN TRANSGENIC PLANTS Roger N. Beachy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 STRUCTURE AND FUNCTIONS OF TOBACCO MOSAIC VIRUS RNA Yoshimi Okada, Tetsuo Meshi, and Yuichiro Watanabe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Heliothis ("Bull worm") species are one of the major pests of field crops worldwide, including sorghum, tomatoes, lettuce, and cotton. Pest problems have intensified over the years as the total area given to agricultural host plants has increased. This comprehensive text, written by experienced researchers, assembles biological and ecological research techniques and approaches to Heliothis management: from the fundamental question of defining genetic species to collecting, rearing, and sampling techniques for the construction of life tables; the measurement of predator impact and physiological development; the detection and measurement of behavior, migration, and diapause; population genetics and resistance. Approaches to modelling population dynamics are also explored. This book is intended for beginning research students as well as experienced workers. It will be a valuable reference for entomologists, population ecologists, and agronomists concerned with crop protection.

Soil is formed from the physical and chemical weathering of rocks-processes described historically becau'se they involve eons of time-by glaciation and by wind and water transport of soil materials, which are later deposited in deltas and loessial planes. Soil undergoes further transformations over time and provides a habitat for biological life and a base for the development of civilizations. Soil is dynamic-always changing as a result of the forces of nature and particularly by the influences of man. Soil has been studied as long as history has been documented. Numerous references to soil are found in historical writings such as Aristotle (384-322 Be), Theophrastus (372-286 Be), Cato the E1der (234-149 Be), and Varro (116-27 Be). Some of the earliest historical references have to do with the erosional forces of wind and water. The study of soils today has taken on increased importance because a rapidly expanding population is placing demands never before experienced on the soil. This has led to an increase in land degradation. Land degradation is one of the most severe problems facing mankind. Volume 11 of Advances in Soil Science was devoted entirely to this critical area of soil science. This series, Advances in Soil Science, was established to provide a forum for leading scientists to analyze and summarize the available scientific information on a subject, assessing its importance and identifying additional research needs.

This book is an outcome of a research project on "Sustainable Forestry and the Environment in Developing Countries". The project has been run by Metsantutki muslaitos METLA -the Finnish Forest Research Institute since 1987 and will be completed this year. A major output by this project has so far been a report in three volumes on "Deforestation or development in the Third World?" The purpose of our multidisciplinary research project is to generate new knowl edge about the causes of deforestation, its scenarios and consequences. More knowledge is needed for more effective, efficient and equitable public policy, both at the national and intemationallevels in supporting sustainable forestry in develop ing countries. Our project has specifically focused on 90 tropical countries as one group and on three subgroups by continents, as well as the three case study countries, the Philippines, Ethiopia and Chile. The University of Joensuu has been our active partner in the Philippine study. We have complemented the three cases by the analyzes of Brazil and Indonesia, the two largest tropical forest-owning countries. Some other interesting country studies were annexed to complement our book both by geography and expertise. The United Nations University, World Institute for Development Economics Research, UNUIWIDER in Helsinki Finland has also been partly engaged. Most of the results from its project on "The Forest in the South and North in Context of Global Warming" will, however, be published later in a separate book.

Soil is formed from the physical and chemical weathering of rocks-processes described historically because they involve eons of time-by glaciation, and by wind and water transport of soil materials, later deposited in deltas and loessial planes. Soil undergoes further transformations over time and provides a habitat for biological life and a base for the development of civilizations. Soil is dynamic - always changing as a result of the forces of nature and particularly by the influences of man. Soils have been studied as long as history has been documented. W. H. Gardner told of writings on clay tablets, dating about 1700 Be, in his review, "Early Soil Physics into the Mid-20th Century;' published in Volume 4 of this series. Those writings gave specific instructions on cultivating the soil and seeding crops. Numerous references to soil are found in historical writings, such as Aristotle (384-322 Be), Theophrastus (372-286 Be), Cato the Elder (234-149 Be), and Varro (116-27 Be). Some of the earliest historical refer ences to soil 3000 or more years ago have to do with erosional forces of wind and water. The study of soils today has taken on increased importance because a rapidly expanding population is placing demands on soil that has never before been experienced. Soil scientists have professionally divided themselves into separate disciplines-physics, chemistry, microbiology, mineralogy, genesis, and the like. Studies range from very basic to very applied, and to literally every corner of the earth, and ofthe moon as well."

The Conference on Tropical Rainforest Research: Current Issues was organised by the University of Brunei Darussalam and The Royal Geographical Society, London, and held in Bandar Seri Begawan, Brunei Darussalam, over 8 days in April 1993. Over 160 participants from 22 countries attended the Conference, which was opened on the 9th April by the Brunei Darussalam Minister for Home Affairs, Yang Berhormat Pehin Orang Kaya Laila Setia Bakti Diraja Dato Laila Utama Haji Awang Isa bin Datu Perdana Menteri Dato Laila Utama Haji Awang Ibrahim. The conference was initially intended to provide a forum to present the results of the expedition into the lowland mixed dipterocarp forest of the Temburong District of Brunei Darussalam, which had been jointly organised by the University of Brunei Darussalam and The Royal Geographical Society, London. The 15-month expedition, lasting from January 1991 to March 1992, was based at the then newly-completed Kuala Belalong Field Studies Centre, a research and education facility set up by the University with funds provided by the Brunei Government and Brunei-Shell Petroleum Sdn Bhd. The expedition, with over 70 scientists taking part, received financial support from a wide range of sponsors and Corporate Patrons, including Royal Brunei Airlines, the Baring Foundation, Daiwa-Dicam, Greencard Trust, the Hongkong Bank, Morgan Grenfell and Nomura-Nimco. The conference itself was supported by donations from Brunei-Shell Sdn Bhd, Royal Brunei Airlines and Standard Chartered Bank.

The study of soils has taken on increased importance because a rapidly expanding population is placing demands on the soil never before experi enced. This has led to an increase in land degradation. Land degradation is one of the most severe problems facing mankind. Volume 11 of Advances in Soil Science was devoted entirely to this critical area of soil science. The editors of that volume, R. Lal and B.A. Stewart, defined soil degradation as the decline in soil quality caused by its misuse by humans. They further stated that soil degradation is a major concern for at least two reasons. First, it undermines the productive capacity of an ecosystem. Second, it affects global climate through alterations in water and energy balances and disruptions in cycles of carbon, nitrogen, sulfur, and other elements. Through its impact on agricultural productivity and environment, soil deg radation leads to political and social instability, enhanced rate of deforesta tion, intensive use of marginal and fragile lands, accelerated runoff and soil erosion, pollution of natural waters, and emission of greenhouse gases into the atmosphere. In fact, soil degradation affects the very fabric of mankind."

On the understanding that few people ever read the preface to any book and also on the understanding that even those few people who do read the preface realize that virtually nothing of any substance is ever said, I shall write at such length as will be proportional to my expected readership. The meetings of the International Society on Oxygen Transport to Tissue provide a forum for discussion amongst scientists who, although being from very diverse and specialized backgrounds, have tissue oxygenation as a unifying theme of interest. The wide variety of research material presented in this volume and the multiplicity of the experimental techniques described, should serve as an adequate gauge to the range of expertise and knowledge of the society's members. Such diversity should also stress the importance of the need for multidisciplinary approaches to complex biological problems. In attempting a fundamental characterization of a biological process such as tissue oxygenation, the application of very many separate research skills are necessary, such as mathematics, engi neering, biophysics, biochemistry, physiology, histology and clini cal medicine. The success of the ISOTT has - and we hope - will con tinue to be causing a combination of individuals to direct their specialized knowledge to the many facets of a single proces- tissue oxygenation."

In the past 10 years, there has been a resurgence in interest in soil management and conservation of the soil resource. With the knowledge we have accumulated in the past 100 years, there is the possibility of developing new and innovative ways of effectively managing the soil. The emphasis on sustainable agriculture requires that we understand how to utilize the soil as a viable living resource. To meet the world demand for food within the next 50 years requires a healthy and strong soil resource which can sustain production. With the dedication of the National Soil Tilth Laboratory in 1989, it was decided that one contribution the laboratory could make to agri cultural science would be to foster an exchange of information on soil management. The focus of that interchange centers on long-term soil management. If we are to fulfill the goals of sustainable agriculture, environmental quality, and feeding the world, there will have to be an increased understanding of how to effectively manage the soil. Long-term soil management requires integrated and interdisciplinary research to bring all of the information together in terms which would be applicable to all soils. To accomplish this goal a workshop is held each year, with the exchange of information focusing on a single topic within the framework of developing effective strategies for long-term soil management. With the forum to focus on an individual theme each year, the theme for the initial workshop was "Limitations to Plant Root Growth."

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. I 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. This series, Advances in Soil Science.

Providing a link between theoretical and applied aspects of plant nutrition and agriculture, this book introduces new concepts in plant nutrition. It shows how these can be applied in order to assess the nitrogen status in crops and to improve nitrogen nutrition through optimized N fertilization management. In this way economic benefits can be obtained, while at the same time preventing detrimental effects on the environment. The main agricultural crops - grasses, wheat, barley, Durum wheat, maize, sorghum, grain legumes and potatoes - are covered. The book will be an invaluable source for agronomists.

A knowledge of forest site and forest productivity variables is fundamental to sound forest practice everywhere. The ability to identify sites and site problems correctly and manipulate productivity variables for maintenance or improvement of productivity is the basis of modern forest management. Although the basic facts regarding forest site and productivity apply throughout the world, the application of information and the response to manipulation vary greatly and depend on local forest conditions. The September 1981 World Congress of the International Union of Forest Research Organizations (IUFRO) in Kyoto, Japan was the occasion for the special meeting on Forest Site and Productivity sponsored by the IUFRO Site Group Sl.02. This meeting brought together forest site and productivity researchers from across the world to review current thought and the state of site research. Information not ordinarily available in one place was presented at this meeting. As organizer of the session, I decided to attempt to publish the papers in one volume. Arrangements were made with a publisher, Martinus Nijhoff, and also with the authors. The process of publication has taken longer than desirable, but the volume does appear at an opportune time coincident with the 1986 IUFRO World Congress in Yugoslavia. Material contained in this publication will set the stage for Site Group discussions at the 1986 meeting. This volume assembles the thought of forest research workers from many different countries and therefore many different kinds of forests.

"Reviews of Environmental Contamination and " "Toxicology"contains timely review articles concerned with all aspects of chemical contaminants (including pesticides) in the total environment, including toxicological considerations and consequences. It attempts to provide concise, critical reviews of advances, philosophy, and significant areas of accomplished or needed endeavor in the total field of residues of these and other foreign chemicals in any segment of the environment, as well as toxicological implications.