Urbanization is an increasing trend in modern human societies. As a consequence of increasing settlements natural habitats for many plants and animals are lost. However, even within cities we still find new habitats for many species including flowerbeds, lawns, single trees and flat roofs and even more nature-like habitats such as forest fragments. These habitats differ from those in rural areas. They often harbour a different species composition. Species in urban habitats experience altered environmental conditions, frequent disturbance by human activity, and a changed community missing some of their natural enemies and competitors but also including alien species introduced by humans. Such changed conditions may not only affect the abundance but also the behaviour of native species and their interactions. In this project we study the biodiversity of urban and suburban habitats. A special focus is on the plant and arthropod diversity of forest remnants and related ecosystem functions.