Indicators of sustainable land use: concepts for the analysis of society-nature interrelations and implications for sustainable development

Proposes two concepts for the empirical analysis of society-nature interrelations: first, socio-economic metabolism ± the material and energy flows between societies and their natural environment and second, the colonization of nature ± the sum of deliberate interventions into natural systems aimed at their `̀ improvement'' with respect to socio-economic goals. Discusses empirical examples for sustainability indicators, focusing on landscape processes, and relates land use to the analysis of material and energy flows. This paper relies on research funded by the Austrian Federal Ministry for Research and Transport and the Austrian Federal Ministry for Economic Affairs within the research program `̀ Sustainable Development of Austrian Cultural Landscapes Kulturlandschaftsforschung)''. It has greatly profited from the work of the research team at the Dept of Social Ecology, including, besides the authors, W. Bittermann, K.H. Erb, M. FischerKowalski, W. HuÈ ttler, F. Krausmann, H. Payer, N. Schulz, H. Weisz and V. Winiwarter. Thanks to Antje Haussen Lewis for correcting the English. 2 quantification; and 3 communication. Indicators present information in quantitative form and allow the description of complex social, political, public or natural processes. Thus, they can be seen as an empirical model of reality (Bossel, 1996; Hammond et al., 1995). Indicators of sustainable development should describe progress towards sustainable development. Indicators of sustainable development thus ± implicitly or explicitly ± reflect some model of the interaction between societies and their natural environment. Appraising the performance of socio-economic systems by means of indicators such as GDP, unemployment rates, income distribution, etc., has a long tradition. Such properties are, however, only loosely linked to the ecological impact of socio-economic systems. It has therefore been proposed to extend the usual economic accounting framework in order to account for environmental aspects of the economic process. This has been attempted in two ways. The first approach involves expanding upon the System of National Accounts (SNA) by integrating ecological aspects into a corrected GNP value. In the course of this GNP correction, environmental damages, ecological impacts of the economy and losses of resource stocks are `̀ monetized''. The second approach involves the construction of so-called environmental satellite systems to the SNA ± that is, creating a close link between the SNA and a set of environmental indicators, which shows the overall environmental performance of the economy (United Nations, 1993; Uno and Bartelmus, 1998). While several unresolved fundamental questions hinder the generation of a unique combined ecological and economic accounting framework (Norgaard, 1989), in recent years there has been increased interest in the development of environmental indicators that can be used to construct `̀ environmental satellite'' accounts to the SNA (OECD, 1994; Munasinghe and Shearer, 1995; Bossel, 1996; Hammond et al., 1996). The Pressure-State-Response scheme A recent review by the German Scientific Council on the Environment (SRU, 1998) revealed that most approaches to environmental and sustainability indicators rely on the Pressure-State-Response (PSR) scheme put forward by the OECD (1994). The PSR scheme distinguishes three levels of analysis of environmental problems: 1 the pressures a society exerts on the environment (pressure indicators); 2 the state of the environment (state indicators); and 3 which measures a society undertakes to improve either the environment `̀ repair strategies'') or its own behavior towards the environment (response indicators). The PSR scheme implies a (cyclical) causeand-effect relationship (pressures generate changes in the state of the environment, which in turn lead to environmental policy responses) and is currently widely used by regional, national and international organizations (e.g. UNO, ECE, OECD, EU). The PSR scheme is employed in developing systems of environmental indicators, and it is useful for environmental information systems (e.g. OECD, 1994) as well as for environmental accounting (e.g. Uno and Bartelmus, 1998). However, the PSR scheme has shown itself to be insufficient for developing comprehensive systems of sustainability indicators. There are currently no successful examples of sustainability indicator systems based upon the PSR approach. All current approaches underrepresent the social and economic dimensions of sustainable development and are unable to relate these dimensions to the ecological dimension in a meaningful way. For most indicators, generally accepted sustainability criteria are lacking (SRU, 1998). Relating material flows to land use: footprints and the SPI The Ecological Footprint (EFP) and the Sustainable Process Index (SPI) are two closely related indicators relating industrial metabolism ± that is, socio-economic material and energy flows ± to land use (Wackernagel and Rees, 1995; Krotschek and Narodoslawsky, 1996). Both concepts are founded on the assumption that solar energy (more exactly: exergy) is the only sustainable basis of an economy. The conversion of solar energy to services requires area. Hence, area may be regarded as the main limiting factor for a sustainable economy. A population's material consumption (in the case of the EFP) or the materials and energy needed for an industrial process (SPI) may thus be converted into the area needed to maintain the related material and energy flows in a sustainable way. According to this approach, material and energy flows need area mainly for two functions: 1 for the extraction of resources; and 2 for the deposition of wastes and by-products. Additionally, the area used for the necessary infrastructure (transport, housing, etc.) is [ 178 ] Helmut Haberl and Heinz Schandl Indicators of sustainable land use: concepts for the analysis of society-nature interrelations and implications for sustainable development Environmental Management and Health 10/3 [1999] 177±190 taken into account. Fossil fuel use may be converted to area demand by means of several approaches. For example, one can compute the area needed to produce the equivalent amount of fuel on the basis of biomass in a sustainable way, or, one can calculate the area of new forest needed to sequester the amount of carbon dioxide emitted by the combustion of fossil fuels. If the methodology is applied to a nation, `̀ imported'' areas and domestically used areas may be distinguished. The EFP/SPI concept sums up two different types of land use: 1 direct use of land for production, infrastructure and deposition; and 2 `̀ hypothetical'' land use, based on the premise that CO2 enrichment in the atmosphere is not sustainable. The EFP allows a comparison on a per capita basis between the amount of productive area available and the amount of area needed to sustain current patterns of resource use. The EFP also allows the appraisal of two features of industrial metabolism: the first feature is that the use of fossil fuels and the mobilization of mineral resources reduces the area needed per unit of material throughput. The use of fossil fuels delinks energy use from the amount of actually available area (which is needed if a society relies more or less exclusively on biomass). The second feature is that modern transport technology and infrastructure have delinked land use from the location of resource consumption, thus allowing nations to consume more land than they actually have at their disposal. Metabolism, colonization and indicators Sustainability research aims to understand the interrelations between social and natural systems. However, traditions in the social and natural sciences which tend to neglect or even altogether deny such interrelations pose a hindrance to this approach. For example, most macrosociological theories envisage human societies as purely symbolic systems, as systems of communication (Luhmann, 1986) or cultural meanings, for example. Natural sciences, on the other hand, usually draw a sharp dividing line between their objects of study and the human agency. A conceptual model for society-nature interrelations From the premise that sustainability refers to society-nature interactions (and not to either natural or socio-economic systems in isolation), it follows that any study on sustainable development must find some way to deal with the fundamental gap between nature and society. Hence, it is necessary to develop conceptual models for society-nature interrelationships that are able to serve as a common interdisciplinary framework for both the social and the natural sciences. Building on the simple premise that socioeconomic and natural systems interact, we may conclude that there must be some touching sphere, or agent of interaction, between them (Boyden, 1992; Knoflacher, 1997; Sieferle, 1997a, b). We may look upon this as a part of nature in which most material and energetic processes are governed by societal regulation, or we might equally well regard it as a `̀ physical compartment of society'' (Fischer-Kowalski, 1997; 1998). This leads us to a model which is described in Figure 1. Our model discerns two autopoietic, selfregulated, interacting systems: society on the one hand, and nature on the other. We denote as `̀ culture'' the immaterial world of thoughts, beliefs, values, norms, communication, knowledge, etc. (Luhmann, 1984), and as `̀ nature'' the material world (Figure 1). We may then postulate an interface between society, thought of as comprising culture and the physical compartment of society (PCS), and nature. Nature comprises the PCS and a "natural environment'', the latter being that part of nature not included in the PCS. Any interaction between culture and nature needs some material agent, the most important of course being humans themselves, who may in this context be regarded as part of the PCS. The boundary definitions between the different compartments in Figure 1 are anything but trivial. The boundaries should be thought of not as topographical but as functional boundaries (Fischer-Kowalski et al., 1994; Fischer-Kowalski, 1997). Depending on one's point of view a different boundary becomes `̀ visible''. From the natural sciences' point of view it may be argued that, as humans are natural, all their artefacts are also natural, so the boundary between the PCS and the natural environment becomes arbitrary. However, this neglects that many `̀ natural'' entities, while being subject to the laws of nature, would never have come into existence or to function the way they do without human action and are largely governed by cultural achievements. On the other hand, it is also difficult to separate `̀ culture'' from physical communication and information storage processes; i.e. it is difficult to separate the immaterial from the material compartment of society. [ 179 ] Helmut Haberl and Heinz Schandl Indicators of sustainable land use: concepts for the analysis of society-nature interrelations and implications for sustainable development Environmental Management and Health 10/3 [1999] 177±190 Consequences for environmental indicators For sustainability research, the most important question regards which socio-economic and natural dynamics determine the path of environmental change. For environmental policy and for modeling the human dimension of Global Change, the focus will be on the human-induced part of the interaction. We may thus ask which socio-economic driving forces lead to pressures on the environment, which changes this will cause in natural systems and how these changes will, in turn, impact on society. This impact will, however, concern the `̀ physical compartment of society'' (PCS) and may, in a second step, lead to a perception of environmental change. Since it does not seem appropriate to try to get a hold on this by means of an an indicator approach, we arrive at the following structure for an adequate indicator system (see Figure 1): 1 Socio-economic driving forces: indicators for socio-economic dynamics that lead to pressures on the environment. 2 Pressures on the environment: indicators for interaction processes between the PCS and its natural environment that have potentially detrimental impacts on the environment. 3 Natural states: indicators for the state of the environment. As it is in many cases not possible to attach the label `̀ societal'' or `̀ natural'' to physical objects without referring to their function in a defined process, this category may include indicators for natural processes and status variables describing not only the natural environment, but also certain physical stocks of society. These indicators will focus on environmental changes caused by pressures. 4 Impacts of environmental change on society: environmental change, regardless of its cause (natural or anthropogenic) may impact on society and must, therefore, be taken into account for the construction of a sufficiently complex environmental indicator system. Environmental changes can result in changes in `̀ ecosystem service'' (Hammond et al., 1995). We believe that this classificatory scheme can resolve some of the discussed problems associated with the PSR scheme. Instead of trying to specify criteria for social and economic sustainability ± whereby it is all but possible to reach an ideological consensus (Enquete-Kommission, 1997) ± we propose to operationalize the social and economic aspects of sustainability by including socioeconomic driving forces and impacts of environmental change on society. The addition of `̀ driving forces'' to the OECD scheme reflects the necessity of investigating into the reasons why societies exert pressures on the environment (Hammond et al., 1995). Figure 1 A model for the interaction society ± with reference to environmental indicators [ 180 ] Helmut Haberl and Heinz Schandl Indicators of sustainable land use: concepts for the analysis of society-nature interrelations and implications for sustainable development Environmental Management and Health 10/3 [1999] 177±190 We do not include `̀ response'' indicators because we doubt that they are useful in the context of sustainable development. First, responses include indicators for processes which are fundamentally different from one another ± for example, measures to change driving forces or pressures and efforts to "repair" damaged ecosystems. Second, responses reflect an outdated paradigm of environmental policy, envisaging it as an additional policy field instead of as a fundamental principle requiring major changes in a variety of policy fields. As sustainable development is often seen as an integrative concept, aiming at an integration of environmental policy into social and economic policy, the category `̀ responses'' does not adequately reflect the related information needs. Basic modes of interaction: metabolism and colonization It is common nowadays to consider the relations between society and nature as a material and energetic input-output process in analogy to the biological metabolism of organisms. This physical exchange between societies and nature is widely called industrial, or more generally, socio-economic metabolism (Ayres and Simonis, 1994; FischerKowalski, 1997, 1998). Currently, the concept of metabolism is increasingly used to construct material and energy flow analyses (Adriaanse et al., 1997; Ayres and Kneese, 1969; Boulding, 1973; Bringezu et al., 1997; HuÈ ttler et al., 1997; Schandl, 1998) and is being established as a core paradigm in the fields of industrial ecology, ecological economics and sustainable development (Meyer and Turner, 1994, Erkmann, 1997). Industrial metabolism is an important concept of society-nature interrelations and may be related to many environmental problems such as resource scarcity, pollution, global warming, etc. Material and energy flows can be linked with socioeconomic activities in a quite straightforward way. For example, it is common practice in energy statistics to calculate the final energy consumption of economic sectors and to account for losses in energy conversion from primary energy to final energy. Material flow analyses are currently being improved with the aim of achieving a similarly detailed level of analysis. Any analysis of society-nature interrelationships will, however, be incomplete if it relies solely on socio-economic metabolism. Besides extracting resources and discharging pollutants, societies also intervene into natural systems in order to render them more useful for some socio-economic purpose. Agriculture, for example, influences the species composition and nutrient availability of a defined area of land in order to produce certain kinds of biomass. We call this type of society-nature interrelationship `̀ colonization of natural systems'' and define it as the sum of those social activities which deliberately change important parameters of natural systems and actively maintain them in a state different from the conditions that would prevail in the absence of human interventions. (Fischer-Kowalski and Haberl, 1993, 1997 Fischer-Kowalski et al., 1997). Colonization may affect all kinds of natural systems, from biotopes to organisms (e.g. plant breeding) or genomes (e.g. genetic engineering). It creates systems in which some parameters are still self-regulated while others are manipulated and regulated by society through the continous application of work in a broad sense (i.e. human labor, animal labor and work performed by machines). An important part of colonization takes the form of land use, an important socio-economic driving force for the evolution of land cover patterns (Meyer and Turner, 1994). Many human land use activities may be seen as colonization of the affected area's ecosystems. Colonization of ecosystems may affect a great variety of parameters, including nutrient cycles, species composition, soil conditions, hydrologic features and the energy flow, for example. Towards a common perspective on metabolism and land use The interrelations between land use and material and energy flows are neglected in most work on industrial ecology or socioeconomic metabolism. In its effort to establish material and energy flow accounts in close connection with economic statistics the spatial dimension ± the areas needed to extract the materials, process them within society and hand them over to nature again ± tended to be neglected. Land use research, on the other hand, focused on area needed and on the analysis of spatial patterns but did not establish an explicit link to material and energy flow analyses. We will try here to outline a common framework of analysis. Analysing industrial metabolism Current analyses of industrial material flows (e.g. Adriaanse et al., 1997; HuÈ ttler et al., 1997; Schandl, 1998) show that the material turnover of industrial societies consists of about 95 per cent water and air and of about 5 per cent all other materials (fossil fuels, biomass [ 181 ] Helmut Haberl and Heinz Schandl Indicators of sustainable land use: concepts for the analysis of society-nature interrelations and implications for sustainable development Environmental Management and Health 10/3 [1999] 177±190 and mineral materials). The water throughput is important with respect to many environmental problems. Air input is generally not seen as an important environmental problem, but the output of exhausts certainly is. The latter, however, may be traced by concentrating on the throughput of other materials; it is this throughput of other materials that we turn to in the next paragraphs. In recent years studies have revealed that it can be useful to employ the notion of a `̀ characteristic metabolic profile'' of industrial society. Table I reports empirical findings for five countries (Austria, Germany, Japan, The Netherlands, and the USA) for these `̀ other materials''. It shows that the per capita material turnover is quite similar for all five countries if common definitions and calculation procedures are applied and thus supports the notion of a characteristic metabolic profile of the industrial mode of production at the level of about 20 t.cap.yr. Mineral materials used mainly for construction, account for nearly one-half of the total throughput, most of them being added to the stock of buildings and to transport infrastructure. Energy-rich materials ± fossil fuels and biomass ± are the other important parts of the throughput. This material flow is fueled by an energy flow of about 200 to 300 GJ.cap.yr, relying above all on fossil fuels, biomass, hydropower and nuclear energy under modern industrial circumstances (Fischer-Kowalski and Haberl, 1997). Industrial metabolism is characterized by a high consumption level as compared to other modes of production (agriculture, hunting-and-gathering). The material throughput of contemporary industrial societies is about four to six times higher than that of agricultural societies and Third World countries. The consumption level is strongly connected with three socio-economic activities (Schandl, 1998). Construction accounted for more than 50 per cent of the total material throughput in Austria in the early 1990s, energy supply (fossil fuels) accounted for about 15 per cent and nutrition for humans and livestock accounted for approximately 20 per cent. Consumer goods play but a minor role; at least at the level of final consumption, but they might be quite material-intensive if one was to calculate all materials needed for their production in a `̀ life-cycle'' approach. Nevertheless, the overall dynamics of the material throughput of industrial societies is mainly related to the consumption of mineral resources like gravel, stone, fossil-energy carriers, feedstuffs for livestock, timber, cement and iron (Schandl, 1998). The materials flow approach leads to a variety of indicators on various temporal and spatial scales. For example: . Two approaches exist for describing the material throughput of the economy. The first approach focuses on the total material requirement, i.e. a broader concept of society's material input that also includes so-called `̀ ecological rucksacks''. These `̀ rucksacks'' consist of the foreign materials used to produce imported goods; they also consist of domestic materials such as translocation, overburden and erosion, none of which enters the economic cycle (Adriaanse et al., 1997). The second approach includes: first, the total material input ± i.e. the domestic extraction plus imports, measured as the weight crossing the border Ðand second, domestic consumption ± i.e. import plus domestic extraction minus exports. The first approach focuses on lowering the overall environmental burden of products (goods, services) (Schmidt-Bleek, 1993; Hinterberger et al., 1994); the second is preferable for linking economic policy and environmental concerns and increasing the ecological efficiency of a national economy. Both approaches may be used to calculate per Table I The characteristic metabolic profile of industrial societies: domestic use of materials (i.e. domestic extraction plus imports minus exports) in 1991. This table only includes used materials, excludes air and water and `̀ domestic hidden flows'' (overburden, erosion and excavation materials) and the `̀ ecological rucksacks of the imports'' Austria Japan W. Germany (1990) The Netherlands USA Unweighed arithmetic mean Biomass 5.6 1.4 3.3 10.2 3.1 4.7 Oil, coal, gas 3.0 3.3 4.9 6.4 7.7 5.1 Metals, minerals, others 11.2 11.7 10.5 6.4 8.9 9.7 Total domestic consumption 19.8 16.4 18.5 22.4 19.7 19.5 Population in millions 7.8 124.8 63.2 15.0 252.3 5 countries Source: Schandl (1998) [ 182 ] Helmut Haberl and Heinz Schandl Indicators of sustainable land use: concepts for the analysis of society-nature interrelations and implications for sustainable development Environmental Management and Health 10/3 [1999] 177±190 capita values, such as for international comparisons. . Material flow analyses may also be used below the national level. For example, they may be used to calculate the material input per service unit (MIPS), as proposed by Schmidt-Bleek (1993). They may also be used to compare sectors of the national economy and relate the material input of a sector to its contribution to GNP (Schandl and Zangerl-Weisz, 1997). As these examples show, material balances are useful in relating monetary economic processes, as measured with economic indicators, to the ecologically relevant properties of the economy (`̀ physical economy''). The investigation into the interrelation between the economy in monetary terms and the use of natural resources was discussed in the late 1960s by economists such as Daly (1968), Ayres and Kneese (1969) and Leontief (1970). These authors used physical input-output tables (PIOT) as a theoretical and empirical framework. The idea of PIOT has again entered the discussion in recent years (Katterl and Kratena, 1990; Fleissner et al.,1993; Schandl and Zangerl-Weisz, 1997). Stahmer et al. (1997) provided a physical I-O for the German economy, closely related to the monetary I-O but focusing on natural resources. Fischer-Kowalski et al. (1998) proposed a similar method called OMEN (Operating Matrix Economy Nature) in order to get consistent and internationally comparable material input-output balances from the incomplete, insufficient and diverse statistical data which are used for national material flow analyses. In Figure 2 we relate the material and energy flows in Austria to the national territory. Figure 2a shows that 73 per cent of the total material throughput of 205 million tons per year (Mt.yr; 1 Mt = 10 t) is gained by domestic extraction; only about one quarter is imported. About 106 Mt.yr is added to stock, mainly as built infrastructure (buildings, roads, etc.). Outputs to nature are dominated by emissions and wastes. Purposive disposal is mostly fertilizer. Figure 2b shows the total energy flow of Austria in 1991, including such usually neglected parts of the socio-economic energy flow as, for instance, the total amount of biomass used for nutrition and the wood used for so-called `̀ non-energy'' purposes (pulp and paper manufacture, furniture, construction, etc.). It reveals that domestic extraction is less important for energy than for materials, as the import of fossil fuels plays a major role for energy supply. However, biomass is more important than usually accounted for in energy statistics. Although the `̀ physical economy'' appears to be connected to the national territory more than the economy in monetary terms does, Figure 2 shows the extent to which modern means of transport have delinked the places where materials or energy are extracted, produced, consumed and where the off-products are discharged. Metabolism and area use: a framework of analysis Socio-economic metabolism and land use are closely linked processes. The material flows shown in Figure 2 need area mainly for two reasons. First, area is needed for the extraction of materials; agriculture and forestry produce the required biomass and mining provides the fossil fuels and mineral materials extracted in Austria. Area is also used for the deposition of off-products (e.g. the areas needed for waste disposal). Second, area is needed because materials processing takes place within the built infrastructure; primary materials are converted in industrial buildings from raw materials to products which are sold in commercial buildings and consumed in private buildings; the wastes are treated in industrial plants before they are handed back to nature in one way or another. From each of these places to the next, raw materials and products must be transported. If we look at the energetic side of industrial metabolism, we encounter a similar picture. Energy is either gathered as some energyrich material such as biomass or fossil fuels ± in this case the same logic applies ± or energy may be gathered in an immaterial form such as potential energy from rivers or as solar radiation or wind power. All these technologies use area, although in some cases there may be `̀ area recycling'' as in the case of solar collectors situated on the roof. The discharge of energy to the environment usually takes the form of low-temperature, dissipative heat losses and thus usually does not need additional area. However, in some cases, area is needed even for this purpose, examples being for the cooling towers of nuclear or conventional thermal power plants. One approach to connecting material flow analyses to land use is to calculate the area used for the steps of the socio-economic metabolism described above (i.e. the areas used for the extraction and discharge of materials), and the area needed to host the infrastructure. Table II gives a first overview of the area needed for the industrial metabolism in Austria. Table II shows that the amount of material harnessed per unit area is about 2-3 orders of magnitude greater in the case of mining [ 183 ] Helmut Haberl and Heinz Schandl Indicators of sustainable land use: concepts for the analysis of society-nature interrelations and implications for sustainable development Environmental Management and Health 10/3 [1999] 177±190 Figure 2 Socio-economic metabolism in Austria: material and energy flow in the Austrian economy with reference to the national territory [ 184 ] Helmut Haberl and Heinz Schandl Indicators of sustainable land use: concepts for the analysis of society-nature interrelations and implications for sustainable development Environmental Management and Health 10/3 [1999] 177±190