A. Definition

Urban ecosystems apply the ecosystem approach to urban areas. Urban ecosystems are dynamic ecosystems that have similar interactions and behaviours as natural ecosystems. Unlike natural ecosystems however, urban ecosystems are a hybrid of natural and man-made elements whose interactions are affected not only by the natural environment, but also culture, personal behaviour, politics, economics and social organisation.

B. Main Features

Urban areas act as population centres providing goods and services not only for its population, but also for populations worldwide. Urban ecosystems can no longer be considered as a separate entity to the environment as they have direct and indirect impacts on the immediate and wider environments. Many of the environmental problems faced today (eg global warming, water and air pollution and inadequate access to safe drinking water) can be traced back to cities and lifestyle choices. With urban population levels expected to reach 60% in the next 30 years and the majority of urbanisation to occur in developing countries, urban environmental management is being increasingly important.

Urban areas can not exist in isolation. They require inputs from, and waste assimilation functions of, other ecosystems. Ecological footprint analysis has shown that many cities require a productive land and sea area several times the city's size in order to support the population.

The urban ecosystem contains both individual and layered (nested) systems from three spheres: (a) the natural environment, (b) the built environment and (c) the socio-economic environment. In order to develop policies and programs that advance sustainable development and the equitable allocation of resources, each system within the urban ecosystem needs to be recognised as a living entity that constantly changes. This differs from the typical segregated and static management approach. Each system requires dynamic balancing and integration. In addition, the interdependencies and interactions between each system and between the urban ecosystem as a whole and other ecosystems need to be understood. Unhealthy urban ecosystems can lead to local and wider environmental degradation, social problems, economic decline, human health problems and further disconnection from nature.

Multidisciplinary in nature, urban ecosystem management requires a composite of social, environmental, economic and decision making tools and institutions that are flexible and can adapt quickly to changes in one or more systems.

The urban ecosystem approach encourages the alignment of cities to that of natural ecosystems where resources, process and products are used more effectively, creating less waste, requiring less input and viewing by-products as resources.

C. Case Studies and Examples

1. UNEP-IETC - The Ecosystems Approach to Urban Environmental Management
[See link below] 2. United Nations University - Urban Ecosystem Management
[See link below]

D. Target Sectors / Stakeholders

Governments, non-government organisations, research institutions, businesses, experts, decision makers, industry organisations and the community are primary stakeholders in the Urban Ecosystem concept.

E. Scale of Operation

Urban ecosystems cover an urban area.

F. Links

• Huron University Collage - Ecosystem Health
• US EPA - Mid-Atlantic Integrated Assessment
• In Context - Urban Ecosystems
• United Nations University - Urban Ecosystem Management
• UNESCO - Urban Ecosystem Workshop Executive Summary
• UNEP-IETC - The Ecosystems Approach to Urban Environmental Management