Ecosystem Accounting for the Cost of Biodiversity Losses: Framework and Case Study for Coastal Mediterranean Wetlands Abstract – 31 March 2008
Ecosystem accounts are used to describe the way ecological systems change over time in terms of their structure and capacity to provide benefits to people. The methods used in this study have been developed by the European Environment Agency and its partners, both as an operational tool and as part of the work being led by the UN to revise approaches to integrated economic and environmental accounting. This study takes the approach further, however. Using the coastal wetlands of the Mediterranean as a test case, it shows for the first time how we can use remotely sensed data from GlobCover define and map socio-ecological systems. It also shows how we can integrate satellite and field data to build up a set of accounts for them to track how they have changed between 1975, 1990 and 2000. A range of biophysical measures are used for the accounts that allow the impacts of change on biodiversity and ecosystem services. These accounts now provide a framework in which the value of these ecosystems and the services associated with them can be assessed, and the costs of biodiversity loss examined.
Coastal wetlands are a particularly interesting ecosystem in which to test the use of accounting methods for calculating the costs of biodiversity loss to Society, because they are particularly sensitive to human impact. At global scales wetlands are amongst the most threatened ecosystems as a result of drainage, land reclamation, land conversion, pollution, and overexploitation, and those found in the Mediterranean are no exception. It has been estimated that more than half of all Mediterranean wetlands have been lost. Salt marshes, for example, have been progressively ‘reclaimed’ and converted to arable or industrial land. Nevertheless, many important areas remain, and in some areas people’s livelihoods are closely linked to the health and integrity of coastal wetland systems, particularly in southern Mediterranean countries.
The benefits that people gain from wetlands include the production of food, freshwater and building materials, but services such as the protection from flooding and coastal erosion, carbon storage and sequestration, and opportunities for tourism. Many wetland areas have enormous cultural significance for people. Although is hard to quantify it has recently been suggested that a ‘conservative’ estimate of the global value of the services associated with wetlands generally is around $3.4 billion per year. The problem with such estimates, however, is that many of the services are outside conventional markets, and so their real value is difficult to capture. This study shows, however, how the new tools being developed for valuing biodiversity and the services it supports can be used within an accounting framework to track how marginal values change over time or what the costs of maintaining the integrity of these systems are relative to the benefits they provide. Ultimately such measures will be able to give us new insights into how we can modify our more traditional measures of wealth, such as GDP, to take better account of environmental externalities.
The costs of biodiversity loss are felt at a range of scales, from the local through to the global. This study shows how accounting methods can be used at a number of different geographic levels. Good information is available for the whole European Mediterranean area in the form of CORINE land cover for 1990 and 2000. For the costal areas these data have been extended back to 1975, so that change over a much longer period can be assessed. These data show patterns of land conversion that impact on the integrity and health of wetlands in the area. In Spain, for example, wetland areas have been lost through urban sprawl. In parts of Spain, Greece and northern Italy, there has also been the extension of irrigated agriculture into wetland areas.
An important feature of the accounts presented here, however, are the new spatial modelling techniques for mapping both biodiversity potential and the pressures upon it. Ecological potential, which describes the capacity of systems to sustain biodiversity and provide ecosystem services, has been captured using methods that identify 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 has been characterised through measures of urban and agricultural ‘temperatures’, which takes into account internal pressures as well as those of 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 for Andalucía.
Although it is important to track global and regional patterns of change, it is important to remember that many decisions that impact on biodiversity and ecosystem services are often made locally. Thus we also need tools to help land managers and planners to look at issues relating to biodiversity at much finer spatial scales. This study shows how accounting methods can be applied at both the ‘macro’ and ‘micro’ scales. As part of this study, detailed, local accounts have been developed for four important wetland areas in the Mediterranean Basin: Doñana in south west Spain, the Camargue in southern France, the Danube Delta in Romania, and Amvrakikos in Greece. To a large extent the changes in these areas mirrored those seen in the regional analysis. All showed evidence of increasing urban and agricultural pressure. A decline in ecological potential was observed in Camargue and even more in Doñana, the only two test case areas for which complete data were available. This decline is small but concerns areas which are under international conservation schemes.
For those interested in calculating the costs of biodiversity loss, the challenge is now to convert the biophysical changes we find in these regional and local ecosystem accounts into monetary values. A start has been made in this study in that researchers are assembling the values of ecosystem services associated with each area. In the future, however, it is likely that a much broader and integrated understanding of the calculation of costs will be needed as we learn more about these systems. For example, it has recently been shown that the loss of wetland has considerable implications for the patterns of migratory birds. As wetland habitats are lost due to agricultural expansion and urban sprawl fewer staging areas are available, and wild birds become more concentrated on the remaining wet areas where they increasingly come into contact with the poultry kept for domestic food production, so increasing the risks of transmission of bird flu. Thus the ‘insurance value’ that more extensive natural wetlands provide need to be better understood.
The calculation of the value of biodiversity and the costs that result from its loss is a formidable problem. We need both robust data and tools to help people use these estimates in their decision making. This study shows how ecosystem accounting provides such a foundation. Although we have only considered wetlands, these tools are applicable to all type of ecosystem and can be used to promote a more holistic or Ecosystem Approach to policy and management.
Conclusions related to ecosystem and ecosystem services accounting:
- Ecosystem accounts are an open framework in which can co-operate the different approaches (schools) of ecosystem assessment (physical, monetary, multi-criteria) and valuation (services value and value of maintenance costs) into a common project.
- Being part of the UN SEEA backed upon the UN System of National Accounts (SNA) gives ecosystem accounts an additional chance of reaching key policy makers.
- Accounts needs to be implemented at different scales. Macro-ecological accounts – connected to local accounts – can be developed with the support of Earth observation programmes (GEO, GMES), and statistical networks (Eurostat, UNCEEA, UNSD...). Micro scale accounts can be established on purpose by a range of public actors and by companies for calculating complete ecosystem costs and benefits. The implementation can start now.
- Multi-functionality of ecosystems is a major issue for assessments. In many cases, ecosystem degradation results from the preference given to one or a very limited number of services: particular food, fiber or energy crops in agriculture, timber in forestry, fish in fishery and fish farming, navigation in estuaries or deltas... It leads to ignore other services such as ancillary products, recreational services or regulating services (soil or fish stocks regeneration, pest regulation or water regulation, carbon storage and sequestration).
- Ecosystem services can be measured and valued one by one, according to uses and users. Generally, significant results are obtained when focusing on important services. This accounting is important as shown in several applications such as in the Green Accounts for Indian Sates (GAISP), the Catskill catchment water supply service or recent work on the insurance value of mangroves. Significant numbers have been found in the Mediterranean wetlands case studies as well. Focusing on broad services with a well identified use, these accounts bring efficient numbers into economic calculation and policy debate.
- A holistic approach of ecosystem services, present and future, can be carried out on the basis of the maintenance of the ecosystems which deliver them. The value obtained is not that of the ecosystem services but instead, that of a minimum reinvestment in nature needed to guarantee sustainable ecosystem services delivery. This approach reflects ecosystem multi-functional potential whoever the beneficiaries of the services in present or future times (it is not sure that the services preferred today will be the same to-morrow) as well as risks linked to resilience of the ecosystems under users’ pressure (one of them being biodiversity loss). Additional maintenance costs of ecosystem potentials can be computed in reference to stated official targets.