In the past years, much work has been carried out on either life-history evolu tion or structure and function of food webs. However, most studies dealt with only one of these areas and often touched upon the other only marginally. In this volume, we try to synthesize aspects of both disciplines and will concen trate on how the interactions between organisms depend on their life-history strategies. Since this is a very comprehensive topic, this volume will focus on vertical interactions to remain within a clearly arranged field. We present some scenaria based on life-history variation of resource and consumer, and show how particular patterns of life-history combinations will lead to particular patterns in trophic relationships. We want to deal with the selective forces underlying these patterns: the degree of specificity of the consumers deter mines the dependence on its resource, and its adaptation to the spatial and temporal availability of the resource. In this respect, the spatial structure of the resource and its "quality" may play an important role. The impact of natural enemies is another important selective force which may influence the evolu tion of interactions between species and the structure of communities. Here, the acquirement of an enemy-free space may provide selective adavantages. The importance of the impact of enemies is also expressed by the development of numerous and sometimes very subtle defense strategies. This will be dem onstrated especially for various aspects of chemical ecology.

This book presents new approaches to studying food webs, using practical and policy examples to demonstrate the theory behind ecosystem management decisions.

All those who think that bivalves are boring are in the best company. Karl von Frisch is reported to have turned the pages more quickly in texts where bivalves were treated because, according to him, they literally lack any behaviour. The fact that they can filtrate huge amounts of water, burrow into the sedi ment, actively swim, drill holes into rocks and boats or detect shadows with the aid of pretty blue eyes located on the rim of their mantle obviously left v. Frisch unimpressed. Why, then, a book on the large freshwater mussels (Naiads or Unionoida), which on first sight are much less spectacular than the marine ones? The main reason is that they are keepers of secrets which they reveal only on close and careful inspection. This is not only true for the pearls some species produce and which over centuries have contributed to the treasures of bishops and kings, but particularly for their ecology: their life cycles are linked with those of fishes, some can occur in incredible densities and some can live for more than 100 years. Thus, the presence or absence of naiads in a lake or stream has manifold implications.

This volume highlights recent advances that have contributed to our understanding of spatial patterns and scale issues in microbial ecology. The book brings together research conducted at a range of spatial scales (from μm to km) and in a variety of different types of environments. These topics are addressed in a quantitative manner, and a primer on statistical methods is included. In soil ecosystems, both bacteria and fungi are discussed.

In the course of evolution, a great variety of root systems have learned to overcome the many physical, biochemical and biological problems brought about by soil. This development has made them a fascinating object of scientific study. This volume gives an overview of how roots have adapted to the soil environment and which roles they play in the soil ecosystem. The text describes the form and function of roots, their temporal and spatial distribution, and their turnover rate in various ecosystems. Subsequently, a physiological background is provided for basic functions, such as carbon acquisition, water and solute movement, and for their responses to three major abiotic stresses, i.e. hard soil structure, drought and flooding. The volume concludes with the interactions of roots with other organisms of the complex soil ecosystem, including symbiosis, competition, and the function of roots as a food source.

At present, roughly half of the world's population lives in urban centers. There are now more than 20 cities with a population of over 10 million inhabitants, compared to less than 5 about 50 years ago. This tendency toward urbanization is expected to continue, particularly in the developing world. A consequence of this growing trend is that millions of people are being exposed to harmful levels of urban air pollutants caused mainly by emissions from motor vehicles and from industrial and domestic activities involving the combustion of fossil fuels. The driving force for the design and implementation of emission control strate gies aimed at improving air quality has been the protection of the health of the population in urban centers. There are, however, other consequences of the pres ence of air pollutants besides the direct effect on human health. Reduced visibil ity, damage to monuments and buildings, and many other such consequences indirectly affect our quality of life. Another set of consequences involves damage to ecological systems. In fact, the nature of "photochemical smog" was first uncovered in the 1950s in connection with observations of its harmful effects on crops and plants in the vicinity of Los Angeles.

This volume presents a body of research conducted over more than thirty years, including an intensive interdisciplinary five-year study begun in 1991. Chapters include studies of the relationships of biogeography and climate to the region's air pollution, the chemical and physiological mechanisms of ozone injury, as well as the impacts of nitrogen-containing pollutants and natural stresses on polluted forests.