Ecosystem Services

Definition:  Ecosystem services are the benefits that people derive from the structures and processes generated by ecological systems.  Ecosystem services are classified into four categories: 1) Supporting services that provide the ubiquitous capacities of ecosystems to function, and to provide other more immediately useful services.  Supporting services include evolution, soil formation, nutrient retention, formation of atmospheric oxygen, and biomass production.  2) Provisioning services are products obtained from ecosystems, such as fresh water, fiber, genetic resources, medicines, and protein.  3) Regulating services are those that moderate climate, natural disturbances, water flow, and some human diseases.  4) Cultural services are non-material benefits, such as aesthetic, social, and spiritual benefits.

Examples:  People receive an abundance of services from ecosystems.  Unfortunately, in the absence of economic valuation, many ecosystem services are unrecognized by society.  In urban systems, services are diverse.  Trees provide a cooler summer environment, reduce heat stress, and protect walkers from UV radiation.  Urban vegetation and streamside habitats can contribute to reduction in the height of urban flooding.  A diversity of wildlife may reduce the impact of the vectors of some human diseases, such as Lyme disease.  Urban soils can absorb pollutants, and trees can reduce violence, or promote healing.  

 

Figure 1.  Ecosystem services include the basic support for life on Earth, the provisions people require, regulation of environmental conditions and mitigation of hazards, and the availability of non-material experiences or values.  Adapted from the Millennium Ecosystem Assessment.

Why important: Ecosystem services are in some cases, irreplaceable.  For example the production of food is a strictly biological process.  This is a process that can become more available in cities, where many residents have poor access to fresh fruits and vegetables and rely on diets high in processed foods.  The reduction in domestic violence, crime, and sickness that are often associated with vegetation are important benefits that are hard to engineer.  The spiritual experience of a connection to the “other” provided by urban wildlife is a benefit that would otherwise only be obtainable by traveling to distant natural locations.  The benefit of reducing stormwater flow, with their normal loads of sediment and pollutants, to coastal waters or rivers that flow through cities is potentially a major contribution to water quality nationwide.  As a majority of citizens come to live in urban areas in both industrialized and developing countries, the improvement of ecosystem services in cities and suburbs is a major need.  It would be impossible in current financial and technological circumstances to replace the services provided by ecosystems with engineered or built solutions.

For more information:

• Millennium Ecosystem Assessment. 2003. Ecosystems and human well-being: a framework for assessment. Island Press, Washington DC.
• Kinzig, A., W.R. Burch, N.B. Grimm, P. Groffman, J.M. Grove, C.W. Martin, and R. Pouyat. 1999. Patch dynamics and ecosystem services: a cross-site comparison of Baltimore and Phoenix.
• Daily, G.C. 1997. Introduction: what are ecosystem services? Pages 1-10 in G.C. Daily, editor. Nature's services: societal dependence on natural ecosystems. Island Press, Washington DC.