Restoration ecology in an urbanizing world

Abstract

As the world becomes more urbanized, the need for ecosystem services in our population centers has become a priority. The restoration of functioning habitats within cities is being successfully attempted throughout the world. Urban sites available for restoration ecology progress are usually small, surrounded by urban infrastructure, and isolated one from another. This fragmentation constrains the quality of natural communities that are pragmatic ecological targets. Defi ning restoration goals also must deal with urban abiotic stresses, including the heat island effect, disturbed soils, modifi ed local hydrology, and chemical pollutants in the air, water, and substrate. Existing biodiversity in cities also has atypical taxonomic structure, driven by the loss of many plant and animal species from the original site communities compounded by the addition of non-native plants and animals with high reproductive rates that invade the native remnants. These invasives can further reduce site biodiversity. Changing community structure includes an overabundance of herbivores such as deer in North America and introduced insects on all continents. Also, the availability of mutualist species needed for community persistence may be low. Progress in urban ecological restoration requires remedies to mediate the physical and biological changes. Political organization for restoration progress will require cooperation among levels of government and building of new teams of ecologists, engineers, and design professionals to manage restoration planning. However, progress on all continents show that urban ecological restoration has developed successful protocols and can contribute to our cities’ environmental and public health.