What is urban ecology? What do we know about nature in the city and how can cities be ecologically structured? What roles do climate, water balance, and soil play in urban areas? Which plants and animals have adapted particularly well to city life? How do urban residents intentionally or unintentionally intervene in natural interactions? What significance does urban planning have, and what challenges of global change must cities increasingly address? These and other fundamental questions of the urban human-environment system are explained in detail and clearly by the author. Key statements in the margin summarize the most important content and findings concisely, while numerous illustrations and tables clarify the issues and facilitate understanding. A reference system with an extensive bibliography and index allows for further exploration.