Ecosystem accounting and the cost of biodiversity losses — the case of coastal Mediterranean wetlands


Courtesy of European Environment Agency (EEA)

Executive summary

The way people are thinking about biodiversity is changing. Until recently, arguments in support of the conservation of species and habitats were based primarily on issues such as their evolutionary uniqueness, rarity or threat of extinction. Today, these arguments also include how maintaining biodiversity directly benefits people by contributing to well-being or quality of life. This new angle means that questions about the costs of biodiversity loss to society have become paramount.

This report focuses on ways we can use land and ecosystem accounting techniques to describe and monitor the consequences of biodiversity loss in the coastal wetlands of the Mediterranean. These ecosystems are characterised by the close coupling of
economic, social and ecological processes, and any accounting system has to represent how these key elements are linked and change over time. This report discusses the importance of estimating the ecological and social costs of maintaining these systems, and the problems surrounding providing monetary estimates of the services associated with wetlands. It also shows
how individual wetland socio-ecological systems (SES) can be defined and mapped using the remotely sensed land cover information from Corine Land Cover.

Although socio-ecological systems have no crisp boundaries, and any mapping is an approximation even at the local scale, this study shows that consistent mapping of such units can be achieved by aggregating combinations of land cover types
that are considered typical of them. In this instance a set of core areas were identified using the wetland classes of the Corine classification, and these were expanded by enlarging the boundary of the SES using a 5 km buffer, to include associated cover types such as irrigated areas, dunes separating wetlands from the sea, and settlements surrounded by these elements. Using this procedure, 159 individual coastal wetland SES were mapped across the Mediterranean basin (1). Ecosystem accounts for these systems were then prepared at pan‑Mediterranean, regional and local scales.

This report also shows that land cover information can be used to build basic ecosystem accounts for stock and change across different scales, and that indicators of change in ecological condition can be built using the new sources of Earth observation data that are becoming available. New spatial modelling techniques have been used to assess the biodiversity characteristics and ecological potential of wetland sites and the pressures upon them. New indicators proposed include ecological potential. This describes the capacity of systems to sustain biodiversity and provide ecosystem services based on the measurement of the density of high biodiversity value cover types at different spatial scales, and the fragmentation of such areas by roads and other infrastructure. Pressures upon ecological systems have also been characterised by indicators based on measures of urban and agricultural 'temperatures'. These measures take into account internal pressures as well as those from the neighbourhood of the ecosystems.

Using these different types of measure, novel types of account have been created that show the spatial relationships between areas of high ecological potential and the pressures upon them, and how both appear to be changing over time. In the study, socio-ecological systems dominated by wetlands were identified in the Mediterranean for 31 administrative regions. Of the 15 for which complete data were available, 14 showed an increase in urban temperature between 1990 and 2000, and all showed a loss of ecological potential. The largest change was in Andalucía.

The work demonstrates that understanding the linkage between spatial scales is particularly important – because as the case of Mediterranean wetlands illustrates, ecosystems are spread across many jurisdictions, and the data collected locally may
vary in its content and quality. Thus it is often difficult to build up a consistent picture using locally derived  information sources. The results presented here show how broad-scale data can provide important contextual information for assessments at local scales. The report concludes with an analysis of four wetland case study areas: Doñana; Camargue, Amvrakikos and the Danube delta. Although the accounts developed reflect the particular issues and pressures that are found in these different areas, it is clear that a generic accounting methodology can help set the problems of individual sites in a broader context.

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