Mapping ecosystem service supply, demand and budgets

Abstract

Among the main effects of human activities on the environment are land use and resulting land cover changes. Such changes impact the capacity of ecosystems to provide goods and services to the human society. This supply of multiple goods and services by nature should match the demands of the society, if self-sustaining human–environmental systems and a sustainable utilization of natural capital are to be achieved. To describe respective states and dynamics, appropriate indicators and data for their quantification, including quantitative and qualitative assessments, are needed. By linking land cover information from, e.g. remote sensing, land survey and GIS with data from monitoring, statistics, modeling or interviews, ecosystem service supply and demand can be assessed and transferred to different spatial and temporal scales. The results reveal patterns of human activities over time and space as well as the capacities of different ecosystems to provide ecosystem services under changing land use. Also the locations of respective demands for these services can be determined. As maps are powerful tools, they hold high potentials for visualization of complex phenomena. We present an easy-to-apply concept based on a matrix linking spatially explicit biophysical landscape units to ecological integrity, ecosystem service supply and demand. An exemplary application for energy supply and demand in a central German case study region and respective maps for the years 1990 and 2007 are presented. Based on these data, the concept for an appropriate quantification and related spatial visualization of ecosystem service supply and demand is elaborated and discussed.

Introduction

There is no doubt about the increasing popularity of the ecosystem service concept in contemporary science (Seppelt et al., 2011, Fisher et al., 2009). The longer the conceptual orientation phase of the ecosystem service approach has been lasting, the more obvious become the needs for practical applications of the concept (Daily et al., 2009, Burkhard et al., 2010). These applications are necessary in order to improve the concept and make it an acknowledged tool for natural resource management (Kienast et al., 2009). The quantification and implementation of ecosystem goods and services have been among the biggest challenges of current ecosystem science (Wallace, 2007). Monetary approaches like cost-benefit analyses, contingent valuations or willingness-to-pay assessments are useful attempts (Farber et al., 2002) but their outcomes are often disappointing due to the economic focus and the lack of appropriate pricing methods, e.g. for non-marketed goods and services (Ludwig, 2000, Spangenberg and Settele, 2010).

The provision of ecosystem services depends on biophysical conditions and changes over space and time due to human induced land cover, land use and climatic changes. Spatial patterns of land cover and land cover change can be linked to large regions and provide direct measures of human activity (Riitters et al., 2000). Because of the spatial peculiarity of ecosystem services, mapping their distributions and changes over time has the potential to aggregate complex information. This visualization of ecosystem services can be used by decision makers, e.g. land managers, as a powerful tool for the support of landscape sustainability assessments (Swetnam et al., 2010). Unfortunately, there is a clear lack of information relevant to local scale decision making (Turner and Daily, 2008). Therefore, the explicit quantification and mapping of ecosystem services are considered as one of the main requirements for the implementation of the ecosystem services concept into environmental institutions and decision making (Daily and Matson, 2008).

In recent years, many new ecosystem service mapping approaches have been developed and applied at different spatial scales by several authors. For a more detailed review of recent approaches to ecosystem service mapping at different spatial scales we refer to Burkhard et al. (2009). Novel studies and approaches on ecosystem service mapping are presented in this special issue (e.g. Schneiders et al., 2012, Koschke et al., 2012, Haines-Young et al., 2012, Nedkov and Burkhard, 2012, Scolozzi et al., 2012).

However, the direct comparison of ecosystem service supply and demand in spatially explicit maps is rather rare in spite of the wide agreement about the importance of including the demand side into ecosystem service assessments (van Jaarsveld et al., 2005, McDonald, 2009). Paetzold et al. (2010) note that the status of an ecosystem service is influenced not only by its provision, but also by human needs and the desired level of provision for this service by the society, which connects supply and demand of ecosystem services inseparably (Syrbe and Walz, 2012). Paetzold et al. (2010) developed a framework for the assessment of ecological quality which considers the supply as well as the demand of ecosystem services. van Jaarsveld et al. (2005) present a practical application of ecosystem supply and demand mapping at the subcontinental scale for Africa, whereas (Kroll et al., 2012) provide a method for the quantification and mapping of ecosystem services at the regional scale for a rural-urban region in eastern Germany. These maps can be used by decision makers for the identification of supply–demand mismatches across landscapes and their changes over time (Paetzold et al., 2010). However, caution and patience are still needed as the expectations from practitioners are already very high, but most of the maps might still need further refinement with more detailed spatial data and better socio-economic information (Kienast et al., 2009).

When assessing and mapping ecosystem service supply and demand, the problem of a clear distinction between ecosystem functions, services and benefits is of high relevance (de Groot et al., 2010, Haines-Young and Potschin, 2010, Burkhard et al., 2010). For several practical reasons, the commonly used definition from the Millennium Ecosystem Assessment “ecosystem services are the benefits humans obtain from nature” (MA, 2005) and the related four categories of supporting, provisioning, regulating and cultural services are not always appropriate (Seppelt et al., 2011, Seppelt et al., 2012, Wallace, 2007). As Fisher and Turner (2008) point out, we have to delineate between ends and means if we want to operationalize ecosystem services. Therefore, Boyd and Banzhaf (2007) introduced the term final ecosystem services which are components of nature directly enjoyed, consumed or used to yield human well-being. Most of the other components and functions of an ecosystem would then be intermediate products respectively intermediate services. This goes along with Fisher and Turner (2008) who propose that ecosystem services’ benefits must have a direct relation to human well-being. For example, nutrient cycling is an ecological function, not an ecosystem service (Boyd and Banzhaf, 2007). However, the distinction between intermediate and final services is often observer-based and depending on rather subjective decisions.

Therefore, we follow a framework which integrates the concept of ecological integrity as the base for the supply of regulating, provisioning and cultural ecosystem services (Müller and Burkhard, 2007). Ecological integrity means the preservation against non-specific ecological risks that are general disturbances of the self-organizing capacity of ecological systems. This self-organizing capacity is based on structures and processes in ecosystems, and appropriate indicators for their description have been defined and applied in several case studies (Müller, 2005, Burkhard and Müller, 2008). Land use and related land cover modifications have a strong impact on ecological integrity. Alterations of ecological integrity lead to increasing or decreasing supplies of selected or bundles of ecosystem services, on which human societies depend.

If the supply of ecosystem services is changed, human societies’ demands for ecosystem services might not be fulfilled anymore. However, it is difficult in today's complex and globalized world to follow the tracks and define the origin of goods and services consumed by people in a certain region. Many goods and services are imported from more or less remote places. In this way, the environmental impacts of ecosystem service generation are exported and leave a biodiversity and ecosystem service footprint elsewhere (Burkhard and Kroll, 2010). Finding an acceptable and equitable level of ecosystem service footprints and an appropriate balance of local ecosystem service supply and demand are important steps toward sustainability. So far, few approaches exist which deal with the relations between local demands and ecosystem service provision elsewhere (Seppelt et al., 2011).

The following definitions are the conceptual background of our approach:

• Supply of ecosystem services refers to the capacity of a particular area to provide a specific bundle of ecosystem goods and services within a given time period. Here, capacity refers to the generation of the actually used set of natural resources and services. Thus, it is not similar to the potential supply of ecosystem services in a certain ecosystem, which would be the hypothetical maximum yield of selected optimized services.

• Demand for ecosystem services is the sum of all ecosystem goods and services currently consumed or used in a particular area over a given time period. Up to now, demands are assessed not considering where ecosystem services actually are provided. These detailed provision patterns are part of the:

• Ecosystem service footprint which (closely related to the ecological footprint's concept; Rees, 1992) calculates the area needed to generate particular ecosystem goods and services demanded by humans in a certain area in a certain time. Different aspects of ecosystem service generation are considered (production capacities, waste absorption, etc.).

According to our definitions, the regional supply of ecosystem goods and services is directly determined by the regional ecological integrity which is influenced by human actions and decisions such as land cover change, land use and technical progress. Human well-being (economic, social and personal well-being) is based on benefits derived from the people's actual use of ecosystem goods and services. This actual use of ecosystem goods and services is the demand side of this supply and demand chain (EEA, 2010). The impacts on the demand side are manifold and can include policies, population dynamics, economic factors, marketing, trends, advertising, cultural norms and governance (Curran and de Sherbinin, 2004). Fig. 1 illustrates the conceptual framework which the ecosystem service supply–demand assessments and mapping have been developed upon.

In this context, the following aims were defined for this paper:

• to present a clear and easy-to-apply concept to map ecosystem service supply and demand as well as supply and demand budgets, to derive a concept that is applicable at different scales for various case study regions and that allows for comparison of different ecosystem services, and

• to support the development of simple tools for landscape managers to support sustainability assessments.