Urban Ecology: Patterns of Population Growth and Ecological Effects


Currently, over 50% of the world's population lives in urban areas. By 2050, this estimate is expected to be 70%. This urban growth, however, is not uniformly distributed around the world. The majority of it will occur in developing nations and create megacities whose populations exceed at least 10 million people. Not all urban areas, however, are growing. Some are actually losing populations because of changing economic conditions and population demographics. Whether a city is growing or losing population, governances face unique challenges with respect to infrastructural, water and transportation needs. To meet these challenges, agencies within city government are cooperating by pooling resources and removing conflicting policies, partnering with the private sector to offset costs of infrastructure, and taking new approaches to design infrastructure. By linking ecological theory with urban design, a more integrative approach to create liveable spaces, which are sustainable, can be achieved in rapidly expanding and shrinking urban areas.

Key Concepts:

  • Megacities and shrinking cities are our future. In the nineteenth and twentieth centuries, most of the world's population lived in rural areas. With economic shifts people moved into cities to find employment, better health services, and improved education opportunities.

  • Future cities represent major ecological, social and economic challenges and opportunities. Rapid urban growth creates economic incentives but can fragment, destroy or degrade existing natural ecosystems. Similarly, population losses create economic and ecological opportunities for expansion and growth.

  • Integrating ecological theory in urban design can create a framework for sustainable cities that are adaptive and resilient. Often, infrastructure is designed to meet engineering specifications but do not incorporate ecological functionality. By integrating ecological with the engineering, infrastructure can meet regulations at the same time enhancing the environment.

Keywords: urban; megacities; shrinking cities; ecological design; resilience

Figure 1.

Estimated global population for the world, urban and rural areas from 2000 to 2050. Adapted from UN ().

Figure 2.

Estimated percentage of global population living in urban areas for the world, developed and developing nations from 2000 to 2050. Adapted from UN ().

Figure 3.

Estimated percentage of population in urban areas by geographical regions for 2010, 2025 and 2050. Modified from UN ().

Figure 4.

A designed rain garden to serve as a bioretention facility as part of a watershed restoration project in Baltimore, Maryland. Photos by Ken W. Belt.



Beatley T (2000) Green Urbanism: Learning from European Cities. Washington, DC: Island Press.

Demographia. (2010) World Urban Areas: Populations and Projections. 6th edn. http://www.demographia.com/db‐worldua.pdf.

Dhakal S, Kaneko S and Imura H (2002) Sustainability of Asia's megacities. IHDP Newsletter 3/2002: 8–10.

Dietz ME and Clausen JC (2008) Stormwater runoff and export changes with development in a traditional and low impact subdivision. Journal of Environmental Management 87: 560–566.

Dirzo R and Raven PH (2003) Global state of biodiversity and loss. Annual Review of Ecology, Evolution, and Systematics 28: 137–167.

Doytsher Y, Kelly P, Khouri R et al. (2010) Rapid Urbanization and Mega Cities: The Need for Spatial Information Management. Research study by FIG Commission 3. FIG publication no. 48, 96pp. The International Federation of Surveyors (FIG), Copenhagen, Denmark.

Elmore AJ and Kaushal SS (2008) Disappearing headwaters: patterns of stream burial due to urbanization. Frontiers in Ecology and the Environment 6(6): 308–312 doi:10.1890/070101.

Franzke M (2007) Pixelation: Urban Redevelopment as a Continuing Process. Dessau: Bauhaus Dessau Foundation.

Glaeser E (2011) Triumph of the City: How our Greatest Invention makes us Richer, Smarter, Greener, Healthier, and Happier. New York: Penguin Press.

Grainger A (2008) Difficulties in tracking the long‐term global trend in tropical forest area. Proceedings of the National Academy of Sciences of the USA 105: 818–823.

Groffman PM, Law NL, Belt KT, Band LE and Fisher GT (2004) Nitrogen fluxes and retention in urban watershed ecosystems. Ecosystems 7(4): 393–403 doi:10.1007/s10021‐003‐0039‐x.

Johnson BR and Hill K (eds) (2001) Ecology and Design: Frameworks for learning. Washington, DC: Island Press.

Kötter T (2004) Risks and Opportunities of Urbanisation and Megacities. Proceedings of the FIG Working Week, Athens, Greece. http://www.fig.net/pub/athens/papers/ps02/ps02_2_kotter.pdf.

Masika R, de Haan A and Baden S (1997) Urbanization and Urban Poverty: A Gender Analysis. Stockholm: Swedish International Development Cooperation Agency.

Mavropoulos A (2010) Megacites Sustainable Development and Waste Management in the 21st Century. ISWA 2010 Conference, Hamburg.

Morichi S (2005) Long‐term strategy for transport system in Asian Megacities. Journal of the Eastern Society of Transportation Studies 6: 1–22.

Mulder A (2006) Shrinking Cities, Explaining Local Government Response. Paper presented at the 2006 ENHR Conference, Ljubljana, Slovenia.

Nelson AC (2004) Toward a New Metropolis: The Opportunity to Rebuild America. New York: Brookings Institution Metropolitan Policy Program, 44pp.

Nowak DJ, Wang Jun and Endreny Ted (2007) Environmental and economic benefits of preserving forests within urban areas: air and water quality. In: de Brun CTF (ed.) The Economic Benefits of Land Conservation, pp. 28–47. San Francisco, CA: The Trust for Public Land.

Pimm SL and Brooks TM (2000) The sixth extinction: how large, where and when? In: Raven PH and Williams T (eds) Nature and Human Society: The Quest of a Sustainable World, pp. 46–62. Washington DC: National Academy Press.

Pimm SL, Moulton MP and Justice LJ (1994) Bird extinctions in the central Pacific. Philosophical Transactions of the Royal Society of London Series B 344: 27–33.

Sohdi NS, Brook BW and Bradshaw CJA (2007) Tropical Conservation Biology. Oxford, UK: Blackwell Publishing.

Spirn AW (1984) The Granite Garden: Urban Nature and Human Design. New York: Basic Books.

United Nations. (2008) World Urbanization Projects: The 2007 Revision. Department of Economic and Social Affairs (DESA), Population Division‐Population Estimates and Projections. http://esa.un.org/unup/.

Varis O (2006) Megacities, development and water. Water Resources Development 22: 199–225.

Varis O, Biswas AK, Tortajada C and Lundquist J (2006) Megacities and water management. Water Resources Development 22: 377–394.

Walsh CJ, Roy AH, Feminella JW et al. (2005) The urban stream syndrome: current knowledge and the search for a cure. Journal of the North American Benthological Society 24(3): 706–723.

Further Reading

Bradshaw CJA, Sodhi NS and Brook BW (2009) Tropical turmoil: a biodiversity tragedy in progress. Frontiers in Ecology and Environment 7(2): 79–87.

Douglas I, Goode D, Houck MC and Wang R (2011) The Routledge Handbook of Urban Ecology. London, UK: Routledge.

Forman RTT (2008) Urban Regions: Ecology and Planning Beyond the City. New York: Cambridge University Press.

McDonnell MJ, Hahs AK and Breuste JH (2009) Ecology of Cities and Towns. Melbourne, Australia: Cambridge University Press.

Millennium Ecosystem Assessment. (2005) www.millenniumassessment.org

Naeem S, Bunker DE, Hector A, Loreau M and Perring C (eds) (2009) Biodiversity, Ecosystem Functioning, and Human Wellbeing. Oxford, UK: Oxford University Press.

Niemelä J (2011) Urban Ecology: Patterns, Processes, and Applications. Oxford, UK: Oxford University Press.

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite close
Zipperer, Wayne C, and Pickett, Steward TA(Jul 2012) Urban Ecology: Patterns of Population Growth and Ecological Effects. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0003246.pub2]