ReviewClassification and valuation of soil ecosystem services
Introduction
Soil is one of the more species-rich habitats of terrestrial ecosystems and its functions include biomass production, maintaining nutrient balance, chemical recycling and water storage to name a few (Blum, 2005). Soil is a very slow forming resource, and similarly to other habitats and ecosystems, it is coming under increasing pressures due to anthropocentric activities. The near exclusion of the importance and value of ecosystems and resources, such as soils, in economic decision-making is exacerbating degradation pressures. In order to resolve this, the concepts of natural capital and ecosystem services (ES) have been widely adopted by academics, NGOs and governments and have been gaining in momentum and acceptance (despite disagreement and confusion of terminology — see Table 1 for our definitions of key terms) for the last two decades (Gomez-Baggethun et al., 2010).
Even though many studies (Kumar, 2010) have been conducted valuing ES, services derived from soils have been partially or entirely omitted (Dominati et al., 2010a). We aim to communicate the importance of soil ES by reviewing the existing literature to identify the various ES that soils provide, and proceed to analyses of how concepts related to soil ES and soil natural capital have developed and how services from soils can be economically evaluated. Relying on the widely-adopted Millennium Ecosystem Assessment (MA) framework for ES, we report on various economic valuation methods for soil ES and the value of soil ES in different types of land uses.
Section snippets
Ecosystem service classification schemes
The environment or natural capital can be considered a stock, which similar to man-made capital yields, through its multiple functions, a flow of goods and services into the future (Costanza et al., 1997). Collectively the various services from natural capital have been referred to as ‘ecosystem services’ and are defined as the benefits people obtain from the ecosphere and its ecosystems (MEA, 2005). When assessing the economic value of ES, the services provided by an ecosystem must be
Frameworks for soil ES
Soil ES are defined here as the benefits that people derive from soils (Dominati et al., 2010a). Despite that various frameworks for classifying ES have been put forward and the evident importance of soil health to human welfare, soil's ES are overlooked and to date there is no agreed upon framework for identifying, classifying or valuing them (Robinson and Lebron, 2010). There have been a few attempts to identify and classify soil ES (Table 2). The first study that we know of appeared in Daily
Value in economics
In this paper, examples of how soil ES can be classified and valued economically are highlighted with the purpose of integrating the economic value of soil ES into land-use decision-making processes. A Preferences-based approach to valuation is therefore opted for as opposed to Biophysical approach (for a detailed discussion on valuation of ES see chapter 5 of Kumar, 2010).
In Preferences-based approaches, which are common in economics, valuation is always based on anthropocentric values, i.e.
Concluding discussion
Provisioning of ES is necessary for maintaining economic systems, and is directly and indirectly linked to human well-being. As many ES, including soil ES, are largely non-market goods, they are excluded from formal economic decision-making and therefore undervalued and overexploited. In the case of soils and soil ES, this is revealed through significant threats to soil natural capital. It is clear that soil degradation is driven or exacerbated by human activities such as unsustainable
Acknowledgements
This work is supported by the European Commission 7th Framework Programme as a Large Integrating Project “Soil Transformations in European Catchments” (SoilTrEC, www.soiltrec.eu, Grant Agreement No. 244118). The authors would like to thank David Cook for his assistance with the manuscript and the two anonymous reviewers for their comments and guidance.
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