The Princeton Guide to Ecology

The quantity of each individual service that a particular ecosystem delivers varies over time and place, to some degree independently of other services. It is therefore essential to specify the period and the included area when quantifying or valuing a service. It is important to match, as far as possible, the time and space scales at which the ecosystem and its services are assessed and managed to the scales at which the underlying ecological processes that deliver the services operate. It follows that ecosystem service assessments must also pay thoughtful attention to the period that the assessment covers and the location of the boundaries of the assessed area. Because each service differs somewhat in the time and space distribution of its important ecological and social processes, some compromises are necessary in practice. Very frequently the factors that control ecosystem services (the drivers) operate at scales that may only partially overlap those at which the service is used. It is also commonly found that the governance systems that determine who may use what services and in what amount operate at one or more political or economic scales, often disconnected from either the scales of the ecosystem process or management activities. These cross-scale interactions have the consequence that there is seldom a single, perfect scale for studying or managing ecosystem services: multiscale assessments and management institutions are needed. Use of one ecosystem service typically has consequences for the quantity of other services that can be used. This is known as a trade-off or, if the interaction leads to a net increase in one or more services, a synergy. Determining the appropriate mix of services to be used from a given ecosystem is a complex process for which there is no simple or perfect solution; furthermore, the appropriate mix and accompanying solutions themselves change over time. Reaching an equitable and sustainable set of trade-offs is especially difficult if the people who benefit from the services are different from the people on whose actions the continued supply of the service depends. This situation commonly arises as a result of spatial separation (e.g., between highland farmers and lowland water users), temporal separation (use of a service now versus leaving it for later generations), or differences in the jurisdiction or power of various social groups or institutions.

domain. The range of characteristic scales in time and space at which a particular process (such as the delivery of an ecosystem service) operates

resolution. The spatial or temporal interval between observations

scale. The physical dimensions, in either time or space, of a phenomenon or observation

synergy. A special case of trade-off (also known as a “positive trade-off”) where the use of one service enhances the production of another

trade-off. The relationship between the quantity of one ecosystem service that is used and the quantity of one or more other ecosystem services that can be used

Some ecosystem services are available only in a particular area or at a particular time. An example is the fruit of a wild tree species—it has a season and location of availability. Other services are effectively delivered all over the world, continuously. An example is the

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