The ecosystem services are defined as "direct and indirect contribution made by ecosystems to human welfare" (TEEB, 2015).
Many studies (e.g., TEEB, 2015; MEA, 2005; Costanza et al., 1997) have been conducted to provide information on these services,
and to investigate how they connect ecosystems with society and the well-being of human populations (Haines-Young and Potschin, 2013).
Historically ES have been divided in four groups: provisioning, regulating, cultural and supporting services (MEA, 2005).
However, with this early definition of ES confusion may arise about the distinction of ecological processes and services that generate a benefit
for humans (Haines-Young and Potschin, 2010).
The cascade model defined in Haines-Young and Potschin (2010) helps to clarify the concept (see Fig. 1).
This model path flows from landscape structure or processes to function or capacities to services and finally to benefits.
Thus, an ecosystem yields the potential to deliver a service, which is in turn defined only if it contributes to human well-being.
In a management perspective, the services provided should be evaluated, but also the processes and functions which yield that service
should be understood and considered in management practice.
The ecosystem services concept enables to assess and predict the effects of policies and related management practices on resources
provided by ecosystems, to quantify trade-offs among several services used by humans, and may be very suitable in communication
processes and stakeholder analysis (Diehl et al., 2015).
Recently, the concept has been increasingly included in the impact assessment of development plans and policies (Geneletti, 2013),
thus requiring the development of quantitative predictive tools to assess ecosystem services,
especially for the management of water resources (Grizzetti et al., 2016).