The city is a rich habitat of great biodiversity. Many animal and plant species are now more common in the city than in rural areas. However, urban nature is fragile and planners and policymakers still consider the city to be the exclusive habitat of people. The authors of this book see as an integral part of the urban organism and as such as important to the quality of life. This publication addresses the theory of ecology and biodiversity, city-bound species, urban habitats, and the maintenance of urban nature.