Stephen Farber
Graduate School of Public and International Affairs
University of Pittsburgh
Pittsburgh, PA 15101

Dennis Bradley
USDA Forest Service
North Central Forest Experiment Station
1992 Folwell Ave
St. Paul, MN 55108

In this paper, we outline how the emerging interdisciplinary perspective of Ecological Economics can be of use in providing conceptual and concrete approaches to identifying, understanding, and maintaining those features of ecosystem and human economic interactions that are necessary to achieve sustainable futures for economic and natural systems.


Ecological economics is a policy-oriented perspective that addresses the interdependence and coevolution between human economies and their natural ecosystems. Interest in this area has been prompted by concerns for the adverse impacts of human economic growth processes on natural systems. Ecological economics is positive, in its development of understanding of the physical, biological and social structural and functional relations between economies and natural ecosystems. Ecological economics is also normative in addressing appropriate roles of human economies within natural ecosystems. The guiding norm is the somewhat operationally vague notion of jointly sustainable human and natural ecosystems. Finally, ecological economics is prescriptive, in proposing institutions and behaviors compatible with sustainability norms. Its position as a discipline is on the boundary of economic and natural systems, focussing on impacts of each system on the other.


Ecological economics recognizes that humans and their economies are parts of larger natural ecosystems and coevolve with those natural systems. There is a material and energy basis for the relations between human economies and their ecosystems, defining not only economic, but social, structures and processes. Economies possess general ecosystem properties, such as dynamism, evolution, integrity, stability and resilience. Economies are inextricably embedded in larger natural ecosystems, and exchange flows of materials and energy with natural systems.

What makes humans and their economies unique as a sub-ecosystem is their ability, through willful effort, ignorance and human designed tools, to dramatically restructure and reform processes in ecosystems of which they are a part; and to such a magnitude that human welfare can be diminished or enhanced by those original actions. There are many factual examples (World Commission on Environment and Development, 1987; Goudie, 1994). Some types of economic activities, and the welfare that originates from them, would not be sustainable if they substantially adversely impact natural systems.

The willful effort to extract useful things from natural systems is motivated by the satisfaction of basic biological needs and the seemingly limitless search for pleasure through consumption of goods and through social associations. The magnitude of potential impact on their own welfare through effects on natural systems requires that human decisions be guided by some notion of the value of their actions and the value of their impacts on ecosystems, either in terms of benefits of use or costs of abuse. Some concept of value is required for rational activities of human economies within their natural systems (Page, 1992).

Both the structures and processes of natural systems have identifiable instrumental value to the human economy. These narrow use values my be reflected by the summation of individual values, to the extent they are private. However, natural systems also have aesthetic, moral and cultural values (Sagoff, 1988). These values are more intrinsic and unmeasurable using traditional human preferences. They may not be reflected in the simple summation across social members of individual values, since they are social and not wholly private.

Valuation is made more complicated by the fact that our natural environment is highly likely to shape values through establishing social and economic relations, aesthetic standards and culture. If so, our decisions now about the natural environment will shape future value systems, making values endogenous and, therefore, a poor guide to behavior. A way out of this dilemma is to make valuations of natural systems based on "What we would like to see society become," rather than to ask what current valuations are (Page, 1992). The value of natural systems is then based on their ability to assist us in becoming what we wish to be. The management dilemma is to organize a method for establishing what society wishes to see itself become, then assist in attaining that wish through knowledge of economic and ecological systems, and then to prescribe methods of attainment.

Unless there is evidence to the contrary, an initial working presumption about human society is that any society would like to see the welfare of its members exceed some minimal level, and would like to provide the opportunities to meet the aspirations for a better life (World Commission on Environment and Development, 1987). Such a society would seek to have welfare sustainable above minimum levels and to have a sustainable development toward welfare enhancements, where the latter is interpreted more broadly than growth in material things and includes educational attainment, health, and increases in basic freedoms (Pearce, et al., 1990).


Tools, insatiable wants and the potential danger of ignorance place humans in a unique position of being able to alter their ecosystems in ways that jeopardize their own social and economic structures and processes. While any species could exceed its own natural ecosystem's carrying capacity or diminish that capacity to the point of self-extinction, only the human species has both the will and capacity to jeopardize itself, as well as the will and capacity to avoid it.

Furthermore, our understanding of ecosystems is primitive. We know that structures change through normal succession and evolution, that processes are altered as the structures through which they occur change, that processes have various temporal and spatial scales, and that catastrophic changes can occur without much evident alteration of structures and processes. However, beyond this abstract knowledge and except for a finite number of circumstances, we know too little about ecosystems to be confident that we can predict the full range of impacts of human economies on ecosystems.

Finally, moral systems in human society may be incompatible with what a society would like to see itself become; e.g., individualism and instrumental valuation may be inconsistent with sustainable welfare norms. Social morality is embodied in an entire set of institutions, social relations and views of natural systems.

The ecological economics problem is to address the potential willful capacity of humans to alter their own relatively unknown environment to such an extent that they can adversely impact their own current or future welfare. This means monitoring for instances where this is a serious problem and informing through meaningful communication. It also means making suggestions for altering human behaviors or moral systems that appear incompatible with the sustainability of economic and natural systems, or that are incompatible with what society wishes to become.


The ecological economics problem, outlined above, is addressed through five tasks:

1. Modelling and Science--Understand the interdependence between economic and natural systems, particularly between the structures, processes, and fluxes of material and energy upon which each system depends. This includes understanding the tolerances of ecosystems to human induced changes as well as the tolerances of economies to ecosystem changes.

2. Conditions for Sustainability--Establish conditions on human economies that would allow for the sustainability and growth of human welfare, conditioned upon the sustainability of the economy's supporting ecosystem.

3. Indicators and Signals--Establish indicators reflecting the current status of economies and ecosystems relative to the norm of sustainability, and include measures of ecosystem and economic health. Also, establish signals reflecting potential impacts of human activity on welfare insofar as those impacts result from alterations in ecosystem structures and processes.

4. Instruments, Laws and Institutions--Develop necessary regulatory instruments, laws and associated institutions that assist human economies in attaining sustainable welfare development goals.

5. Moral Systems--Examine the implications of various moral systems for the sustainability of human welfare, and place in bold relief those instances where there are apparent incompatibilities between moral systems and sustainability norms.


In order to understand the management implication of the ecological economics framework, it would be useful to contrast it to a characterization of the current management paradigm. The two paradigms differ primarily on the primacy given to human economies versus natural ecosystems. The Prevailing Management Paradigm focusses on how humans can manage ecosystems for instrumental purposes of optimizing human economic wealth. This wealth is typically measured in the value of utility enhancing things and actions, frequently measured by "willingness to pay" or "willingness to accept" monetary compensation for gains or losses, and by summing across independent individuals. Preferences are typically taken as given and immutable, and the manipulation of natural systems for human benefit addresses those preferences. This management paradigm approaches uncertainty about natural systems by either denying or opting in favor of human economies. If not denying the uncertainty, the optimistic argument is given that natural processes are either reversible with enough time and engineering skill, or economic systems can find human-made replacements for lost ecosystem materials and services. The prevailing issue for this paradigm is "How can we use the ecosystem to more effectively enhance human wealth and welfare?"

An alternative to this paradigm is suggested if we weight more highly the belief that ecosystems are critical to social survival, our ignorance about how ecosystems work, our uncertainty about the full potential value of natural ecosystems to the economy, and our ignorance about preferences of future generations. Ecological economics, using what we may term an Ecological Economic Stewardship Paradigm, would ask the following management questions:

1. What does society wish to become?

2. What is the requisite health of an ecosystem relative to that social objective?

3. What set of human economic artifacts, structures and processes is feasible within that requisite healthy ecosystem?

4. How can we use the adaptability and behaviors of human economies to assure they meet their own welfare needs as well as the needs for preservation of a healthy ecosystem?

This perspective first requires a social dialogue to establish what society would like itself to become. This is primary to development of ecosystem health concepts since it establishes the basic value system from which ecosystem and economic health are measured. In the presence of ignorance about ecosystems, the presumption is made that human systems are adaptable to the constraint of a healthy ecosystem and, possibly, more adaptable than the natural system itself, the latter being more slowly evolutionary and potentially susceptible to catastrophes in response to apparently minor changes. Adaptable and flexible human economic systems are seen as the key to successful long term management of ecosystems. The management focus is shifted from ecosystem manipulation under the prevailing paradigm to exploitation of the adaptability of human economies.

Under the ecological economics Stewardship Paradigm, the primary issue is preserving basic properties of natural systems. Once these are established, the management problem is to develop a compatible adaptation strategy for the human economy to the constraints set by the goal of preservation of natural ecosystem health. Health is defined implicitly by what society would like to see itself and the world around it become. Preserving particular ecosystem forms would not be as important as preserving ecosystem structures and functions, such as nutrient and hydrologic cycles, and preserving the resilience of the ecosystem to dramatic external changes; and allowing ecosystems to evolve rather than face catastrophic change. Long run sustainability of the human economy is viewed within a larger context of sustaining the health and integrity of the natural ecosystem within which humans are embedded. Adaptation requires defining alternative courses of human action and increasing flexibility and resiliency of human economies. Optimal human adaptation and flexibility under the constraints of a long term, healthy, resilient natural ecosystem are the operative concepts in this paradigm.


The ecological economics Stewardship paradigm requires knowledge of how ecosystems and economies work, and how they interact at various spatial and temporal scales. This would be required under any responsible management framework.

First, the ecological economics Stewardship framework requires knowledge of both how natural ecosystems respond to economic activity, as well as how economic activity responds to ecosystem changes. A seemingly useful analytical construct at this boundary is a full ecological-economic, input-output matrix. Flows of material, energy, nutrients, etc. between the economic and ecological systems would be quantified and impacts of one system on the other could be established. Such a model has been well-developed for the economy alone, and ecologists have established energy flow models for ecosystems. However, little progress has been made in coupling these two separate models in any meaningful practical way (Isard, 1972; Daly, 1968; Cumberland, 1987; Costanza and Hannon, 1989). A potentially useful coupling is currently being undertaken at the University of Maryland (Costanza, Bockstael, et al.). An ecosystem model of the Patuxent, Maryland watershed has been developed, where flows of nutrients and energy flow between spatial cells. Economic land uses are predicted, with the ecosystem configuration being an input to that prediction. Land use then feeds back to the ecosystem through runoffs based on land use. The system is dynamic and can be used in a practical way to predict land use and ecosystem configuration.

The appropriate "Scale" and "Mix" of the human economic activity relative to the natural ecosystem are critical issues at the ecological-economic interface (Daly, 1992). The carrying capacity of an ecosystem has been proposed to address appropriate scale, and has been mechanistically applied in some circumstances (Ehrlich, 1994; Hardin, 1991). A single number, for example the number of humans, is meaningless since human innovation and biological evolution may interact to moderate potentially adverse welfare effects of natural systems changes. Also, a level of human welfare must be specified to make the concept operational. A general index of the physical intensity of the human economy relative to the natural system would be useful, such as Vitousek, et al.'s (1986) estimation that humans appropriate forty percent of the net terrestrial primary production of the biosphere, is striking although we do not know what level of appropriation places the health of the natural system at risk. Recent attention has moved toward the notion that an appropriate scale of economic activities would preserve the resilience of the life-support systems on which they depend (Arrow, et al., 1995). Resilience is the ability of the ecosystem to take shocks without making catastrophic changes in structure or processes. In this perspective, indicators of loss of resilience would be used to measure whether the scale or mix of economic activities is "too large."

A more micro issue at the economy-ecosystem interface is the production relation between natural systems and human or human-made capital. First, in a pure production framework, natural systems can be viewed as natural capital (Jansson, et al., 1994; Bradley and Xu, 1994), which is combined with economic and social capital to generate welfare. Considerable social policy energy has been expended in arguing that enhancements in natural capital reduce the need for human or human-made capital. Instances in which natural systems and human-based capital are complementary are most certainly cases where sustainability of the natural system is valuable, if not critical, to human economies in the most instrumental sense. For example, fishing boats have no value absent fishing stock. On the margin, a larger fish stock increases the productivity of human and human-made capital. On the margin, labor is more productive the cleaner the air and water. These relations are the bases for the proposition that jobs and the quality of ecosystems are positively linked (Templet and Farber, 1994). Explorations of these relations between natural systems and human economic productivities are undertaken by a wide range of disciplines.

Second, indicators of sustainable economic health are critical under Ecological Economics Stewardship. Sustaining a flow of income (welfare) requires the maintenance of the source of income, which is wealth (capital). Using the analogy of natural capital, measures of sustainable economic health require the subtraction from traditional economic income an amount necessary to replace any net degradations in the quality of natural capital. The presumption is that these degradations are reversible through investments from the economic sector to the natural sector. Practical examples include full welfare indicators (Daly and Cobb, 1989), and integrated adjustments of National Economic Accounts, or Sector Accounts (agriculture, forestry, fishery, etc), for natural ecosystem degradation (Van Dieren, 1995; Repetto, et al., 1989). The integrated accounts approach seeks to measure sustainable economic welfare by subtracting the loss in potential productivity of ecosystem degradation, or the cost of ecosystem remediation, from positive values of the economy's production of useful goods and services. Valuation of that natural capital loss is made from a purely anthropogenic, current or discounted future generations perspective. The full welfare indicators go further in proposing to measure a more general concept of welfare than that represented by economic consumption opportunities, including such factors as income inequities and crime rates. Non-integrated accounts include, side by side, both traditional economic accounts and some physical indicators of natural system conditions (Bradley and Xu, 1994).

Third, some concept of value must be established since human decisions are going to be based on values gained versus values lost. Valuation could be narrowly based on individual preferences, or more broadly on social preferences. Basic physical and biological needs would have infinite value on an individual basis, but may have only finite values on a social basis. Beyond basic physical and biological needs of human economies, preferences can be viewed as molded by a complex of social, genetic and natural forces. Ecological economics suggests that preferences are mutable and adaptable. Requisite adaptations for sustainability of natural systems, and how these preferences can be reshaped are suggested research issues necessary for managing sustainable economic and natural systems. Furthermore, aggregations of individual values may be less important in valuing ecosystems than the value that society as a whole places on them. Social valuation may be weighted more highly than individual valuations. Studies of the divergence between the aggregate of independent, individual valuations and joint, socially-based valuations, where these individuals set a consensual value in some social decision setting, are necessary before valuing large ecosystems.

Valuations of ecosystem services have typically been from the perspective of current generations and propose that value is represented by the willingness to pay for these services. Extensive valuation methods have been developed by environmental economists (Freeman, 1993) and have been applied to large ecosystems (Farber, 1996). However, these valuation procedures may not be appropriate to valuing such services in a sustainability context. In a sustainability context, ecosystem structure and functions would be evaluated on the basis of the extent to which they contribute to the goal of economic and ecosystem health and sustainability, rather than on the basis of their immediate contribution to current economic welfare.

Valuation of ecosystems based on individual preferences can be useful where spatial scales are narrow and temporal scales are short. However, the dramatic and potentially most serious ecosystem issues, such as global warming, are huge spatial and temporal scale problems. Preference-based valuations appear shallow in this context. For example, an appropriate question would be the willingness of future generations to pay current generations to avoid passing a legacy of a severely degraded ecosystem. Future generations' preferences are simply unknown, albeit possibly formable by current generations, through education and cultural legacies, and adaptable to future circumstances. The current generation's most empathetic valuation would consist of asking "How maximally sorry could the future be if we altered their inherited ecosystem by action X?" Then, "What would the valuation of that sorrow be?" Neither of these questions is answerable. This conundrum may suggest the expedient policy of simply attempting to pass to the future an ecosystem that has the ecological properties of integrity and resilience.

Preference based valuations are further complicated by the time-dependence of benefits from ecosystems. Traditional discounting is preference based. One justification is based on extrapolating the presumption that a unit of something is worth more to an individual today than years from now to the presumption that this would also be true if it were different individuals at different points in time. To avoid this individualistic presumption, economists have suggested using rates of social time preference, which reflect how much an existing society would discount the same society's benefits in the future. The problem with even this social concept is that it places the members of the present society in a position of dictating the legacy to be passed to the future, with the weighting of future generations' welfare less than the current generations'. Arguments are made that discounting is appropriate because investments will be made in the present that will provide a legacy of increased productive capacity to the future, or that the future will be more well-off than the present. Neither of these may be the case; and if economic decisions result in irreversible destruction of ecosystem capital, they will likely not be the case.

A discounting procedure consistent with sustainability goals could be as follows. In making decisions over the management of ecosystems, those changes that would enhance or degrade the human life support capacity of the ecosystem, in the sense of providing for basic physical and biological needs would not be discounted at all; i.e., have a zero discount rate. Those ecosystem changes that impacted welfare above the threshold basic needs level would be discounted, but at the social rate of discount (Mikesell, 1977).

A proposed, purely ecological valuation designed to avoid preferences altogether would value ecosystem structures and processes solely by their capacity to transform energy or matter; hence an "energy-based" valuation (Costanza, 1980; Costanza, et al., 1989). This valuation is extreme in placing a zero weight on human preferences, and may be too sterile to be attractive for ecosystem management, although it is consistent with measuring ecosystem value relative to the goal of preserving ecosystem processes.

as exceeding these points may irreversibly create a catastrophic change in ecosystem form.

Fourth, the Ecological Economics Stewardship focus requires understanding of human economic adaptability. This includes adaptability of preferences to new circumstances, noted above. In addition, this requires knowledge of trade-offs that the human economy has available to meet human needs and wants. Knowledge about preference formation, and the speed and costs of adjustment to changes in markets for economic goods and services are important to understand how the economy can adapt to changes in ecosystem structure and processes.

Fifth, Ecological Economics Stewardship requires the use of property rights systems, laws, and institutions that are incentive compatible with sustainability norms. All economically driven incentive systems that have adverse consequences for ecosystem health (Farber, 1991), and existing institutional impediments to economic adaptability, such as farm subsidy programs and land tenure systems, have to be illuminated to portray their full ecological-economic impact. We are developing increasing knowledge about these perverse incentive systems and institutional barriers to sustaining ecosystem health.


We can distinguish between risk and uncertainty. Classic risk presumes that we know some probability distribution associated with events and states of the world. The concepts of expected value or most likely states are definable. Classic uncertainty presumes there is no a prior knowledge of probabilities. As noted above, the prevailing management paradigm approaches uncertainty about natural systems by either denying or opting in favor of human economies. If not denying the uncertainty, the optimistic argument is given that natural processes are either reversible with enough time and engineering skill, or economic systems can find human-made replacements for lost ecosystem materials and services. Under Ecological Economics Stewardship, there is a presumed higher cost associated with being wrong about reversibility, remediation, and mitigation of degradations in natural system health. A precautionary (Perrings, 1991) or minimum regrets approach to decisions that may adversely impact natural system would opt in favor of ecosystem health protection. The cost of this decision rule may not be so high, particularly if basic human needs are not at stake, since human preferences and economic structures are adaptable.