4.2. The economics of ecosystem services
The concept of ecosystem services has received an increasing attention as a way of communicating about the societal dependence on ecological life support systems [6].A set of studies framed the beneficial use of ecosystems functions as services with the aim of increasing public awareness and policy makers interests in biodiversity conservation [4]. ‘‘Ecosystem services’’, first often examined in ad hoc lists, refer to a set of benefits that are now considered to fall into three distinct economic categories [80]: (i)‘‘goods’’ (products obtained from ecosystems for direct consumption or as inputs for industry, such as resource harvests, and genetic material); (ii) ‘‘services’’ (recreational and tourism benefits or certain ecological regulatory functions, such as water purification, climate or pollution regulation, erosion control); and (iii) cultural benefits (scientific knowledge, spiritual and religious feelings, heritage. . .). In a general framework proposed to evaluate the world’s ecosystems [7], estimates for 17 categories of services, covering all terrestrial and marine environments, were proposed. The value of coastal environments (including estuaries, coastal wetlands,plant communities and algae fields, coral reefs and continental shelves) represents 43% of the total, even though they only cover 6.3% of the surface of the globe.This weight seems to be related to the role that these
environments play in the regulation of nutrient cycles,both terrestrial andmarine, whose valuation inmonetary units seems however to be particularly tricky.The total value of services rendered annually was estimated between one and three times the value of the world gross product, for a large part to coastal and littoral ecosystems. Among the many critics this work received, one questioned the meaning of an asset monetary value higher than the global wealth, a result that assumed implicitly a conception of the wealth going far beyond monetary income.
Extending this framework [7] to 23 functions (regulation,habitat, goods and services, information) De Groot et al. [81] gives the value ranges for all the world ecosystems. Their figures range from a few dollars to often several thousand dollars per hectare and per year.
This degree of variation results not only from differences in the quality of ecosystems and intensity of their uses, but also in the evaluation method, as different techniques do
not capture the same attributes.The Millennium Ecosystem Assessment [1] established of
a consensual framework for documenting, analysing, and understanding social-ecological systems, which has had wide influence in the policy and scientific communities.
Twenty-two ecosystem services are organized in four major categories: provisioning services, regulating services,cultural services and so-called support services,namely interactions within and between ecosystems that do not directly contribute to human well-being but make the other services possible.Although it has become a reference, this classification remains a subject of discussion [23,82–84]. The main concerns are: the mixed public goods character (publicprivate);
the difficulties in understanding the spatial and temporal dynamics, the inability to separate some services produced simultaneously by a same ecosystem; the complexity of the interactions between structures, functions and services; the fact that the agents only identify as services those from which they benefit [82].More recently The Economics of Ecosystems and Biodiversity
(TEEB) [50] proposed a typology of 22 ecosystem services, defined as ‘‘the direct and indirect contributions of ecosystems to human well-being’’. Relatively to the MEA framework [1], it takes apart services and benefits in order to explicitly identify services providing multiple and
indirect benefits. It omits supporting services such as nutrient cycling and food chain dynamics, seen as ecological processes. A ‘‘habitat’’ service has been identified as a separate category to emphasise the importance of ecosystems in providing habitat for migratory species
(nursery service) and gene-pool (namely for commercial species).