Why a second edition? And how different is it from the first? These are two obvious questions that a writer must address. Overall, this is a major revision in form, but built around the same principles. Some chapters, such as Flooding and Fertility, are revised with new figures. Other chapters, including Services and functions and Restoration, are entirely new.

Having had ten years to observe reactions to the first edition, I now have a better understanding of how ecologists in general, and American students in particular, think about wetlands. I have therefore re-balanced and reorganized the book to better reflect these realities. At the same time, I have stuck to the view that a small number of general principles are needed to unify wetland ecology, and that a small set of causal factors are present in all wetlands, albeit in differing relative importance.

Over the book as a whole, I have reorganized the flow of ideas to place causal factors nearer the beginning, and in order of relative importance. Students, then, can start immediately with effects of flooding in Chapter 2 and fertility in Chapter 3. The more conceptually difficult material (such as zonation, biodiversity, and valuation of ecological services) has been moved to later in the book.

Each chapter begins with a few basic principles up front and early, usually accompanied by a few clear examples to illustrate the principle. The more difficult concepts are introduced later in each chapter.