Résumé :
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The book is divided into four sections. The first section, composed of Chapters 2 and 3, deals with the raw material for the study of biological diversity. Chapter 2 discusses the variety of diversity patterns found in ecosystems around the world at spatial scales ranging from the entire globe to soil particles. Presented along with the somewhat confusing diversity of diversity patterns is the even more confusing diversity of environmental conditions that are correlated with them. Chapter 3 briefly addresses issues related to the measurement and quantification of biological diversity. The second section, Chapters 4 and 5, reviews the historical development of theories of species diversity, focusing on the impotance of equilibrium versus non-equilibrium processes in regulating species diversity. Again, the issue is not whether an equilibrium or a non-equilibrium viewpoint is correct, but which of many potential opposing processes are likely to be in equilibrium at a particular spatial and temporal scale. The third section, Chapters 6 through 10, addresses mechanisms of intra and inter-specific competition, particularly among plants, which are the dominant structural organisms in most terrestrial environments and in many aquatic and marine environments. Each chapter deals with the influence of interactions among individual organismes on diversity at a different organization of diversity within populations of single species, manifested primarily as variation in size. Chapter 7 extends the effect of interactions among individual organisms from the population to the community and ecosystem level. Chapters 8, 9 and 10 discuss the major spatial and temporal patterns of the distribution of organisms on landscapes, again in terms of the interactions between individual organisms. In aggregate, these chapters deal with the major components of biological diversity over the range of scales at which they are perceived by humans. The fourth section, Chapters 11 through 14, applies the concepts developed in Parts two and three to some of the major issues in biological diversity and some of the major ecosystems in which species diversity shows the most variability. Endemism and invasions, discussed in Chapter 11, are two of the most dramatic manifestions of variation in the equilibrium between speciation and extinction. Chapter 12 discusses marine systems, ranging from the intertidal to the mid-oceanic benthos, that span the range from low to high species diversity, and illustrate the influence of virtually all the factors that are known to influence species diversity. Chapter 13 deals with a range of terrestrial plant ecosystems in which diversity is regulated by a single type of major disturbance,fire. The diversity of fire-dominated ecosystems ranges from virtually monospecific stands to ecosystems with some of the highest plant diversity found on Earth. Finally, Chapter 14 deals with the sine qua non of biodiversity, tropical rain forests, and comes to what may be perceived by some to be the most counterintuitive conclusion in the entire book I conclude with a brief discussion of some of the economic and conservation implications of the counterintuitive regulation of global diversity gradients.
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