Ecological Integrity
ECOLOGICAL INTEGRITY
Ecological or biological integrity originated as an ethical concept in the wake of Aldo Leopold (1949) and has been present in the law, both domestic and international, and part of public policy since its appearance in the 1972 U.S. Clean Water Act (CWA). Ecological integrity has also filtered into the language of a great number of mission and vision statements internationally, as well as being clearly present in the Great Lakes Water Quality Agreement between the United States and Canada, which was ratified in 1988.
The generic concept of integrity connotes a valuable whole, the state of being whole or undiminished, unimpaired, or in perfect condition. Integrity in common usage is thus an umbrella concept that encompasses a variety of other notions. Although integrity may be developed in other contexts, wild nature provides paradigmatic examples for applied reflection and research.
Because of the extent of human exploitation of the planet, examples are most often found in those places that, until recently, have been least hospitable to dense human occupancy and industrial development, such as deserts, the high Arctic, high-altitude mountain ranges, the ocean depths, and the less accessible reaches of forests. Wild nature is also found in locations such as national parks that have been deemed worthy of official protection.
Among the most important aspects of integrity are the autopoietic (self-creative) capacities of life to organize, regenerate, reproduce, sustain, adapt, develop, and evolve over time at a specific location. Thus integrity defines the evolutionary and biogeographical processes of a system as well as its parts or elements at a specific location (Angermeier and Karr 1994). Another aspect, discussed by James Karr in relation to water and Reed Noss (1992) regarding terrestrial systems, is the question of what spatial requirements are needed to maintain native ecosystems. Climatic conditions and other biophysical phenomena constitute further systems of interacting and interdependent components that can be analyzed as an open hierarchy of systems. Every organism comprises a system of organic subsystems and interacts with other organisms and abiotic elements to constitute larger ecological systems of progressively wider scope up to the biosphere.
Ecological Integrity and Science
Finally ecological integrity is both "valued and valuable as it bridges the concerns of science and public policy" (Westra et al. 2000, pp. 20–22). For example, in response to the deteriorating condition of our fresh-waters, the CWA has its objective: "to restore and maintain the chemical, physical, and biological integrity of the Nation's waters" (sec. 101[a]). Against this backdrop, Karr developed the multimetric Index of Biological Integrity (IBI) to give empirical meaning to the goal of the CWA (Karr and Chu 1999). Karr defines ecological integrity as "the sum of physical, chemical, and biological integrity." Biological integrity, in turn, is "the capacity to support and maintain a balanced, integrated, adaptive biological system having full range of elements (genes, species, and assemblages) and processes (mutation, demography, biotic interactions, nutrient and energy dynamics, and metapopulation processes) expected in the natural habitat of a region" (Karr and Chu 1999, pp. 40–41). Scientists can measure the extent to which a biota deviates from integrity by employing an IBI that is calibrated from a baseline condition found "at site with a biota that is the product of evolutionary and biogeographic processes in the relative absence of the effects of modern human activity" (Karr 1996, p. 97)—in other words, wild nature. Degradation or loss of integrity is thus any human-induced positive or negative divergence from this baseline for a variety of biological attributes (Westra et al. 2000). Noss's Wildlands Project, which aims to reconnect the wild in North America, from Mexico to Alaska (Noss 1992, Noss and Cooperrider 1994) utilizes the ecosystem approach to argue the importance of conserving areas of integrity.
But the most salient aspect of ecosystem processes (including all their components) is their life-sustaining function, not only within wild nature or the corridor surrounding wild areas although these are the main concerns of conservation biologists. The significance of life-sustaining functions is that ultimately they support life everywhere. Gretchen Daily (1997), for instance, specifies in some detail the functions provided by nature's services, and her work is crucial in the effort to connect respect for natural systems integrity and human rights.
Arguments against the value of ecological integrity for public policy have identified the concept as stipulative rather than fully scientific (Shrader-Frechette 1995). In a similar vein even the concept of ecology as such has been criticized as not robust enough to guide public policy (Shrader-Frechette and McCoy 1993). But ecological integrity is already a part of public policy, thus requiring consideration of its meaning and the role its inclusion should play in policy, rather than arguing for its rejection. Further to maintain that "we need a middle path—dictated in part by human not merely biocentric theory" (Shrader-Frechette 1995, p. 141) ignores how humans do not exist apart from other organisms: Biocentrism is life-oriented, and this principle is increasingly accepted not only by science, but in the law.
The routine use of Karr's IBI to reach general conclusions illustrates the ethical effectiveness of the scientific concept of ecological integrity in public policy. The law analyzes a crime or victim under a particular set of circumstances. But public policy must abstract from specifics. Disintegrity (or lack of integrity) and environmental crime (Birnie and Boyle 2002) are global in scope and need international fora and broad concepts to ensure that they will be proscribed and possibly eliminated.
In addition, there is mounting evidence to connect disintegrity or biotic impoverishment (Karr 1993) in all its forms, from pollutions, climate change, toxic wastes, and encroachment into the wild (Westra 2000) to human morbidity, mortality, and abnormal functioning. International law has enacted a number of instruments to protect human rights (Fidler 2001) and the World Health Organization (WHO) invited the Global Ecological Integrity Project (1992–1999) to consult with it. This collaboration eventually produced a document titled "Ecological Integrity and Sustainable Development: Cornerstones of Public Health" (1999) (Soskolne and Bertollini).
The Ethics of Integrity
Because of this global connection between health and integrity, and the right to life and to living (Cançado Trindade 1992), a true understanding of ecological integrity reconnects human life with the wild, and the rights of the latter with those of the former. The ethics of integrity primarily involves respect for ecological rights (Taylor 1998) without limiting these to the human rights that are the primary focus of the law. The main point of an ethic of integrity is that it is a new ethic (Karr 1993), one founded on recent science demonstrating the interdependence between humankind and its habitats. Environmental ethicists may prefer to focus on one or the other aspect of this interconnected whole—biocentrism or anthropocentrism. While biocentrists accept the presence of humankind as such within the rest of nature, anthropocentrists attempt to separate the two, in direct conflict with ecological science.
If, as argued, human health and function are both directly and indirectly affected by disintegrity (Soskolne and Bertollini Internet article), then no theory can properly separate one from the other. The strength of the proverbial canary-in-the-mine example is based on the fact that the demise of the canary anticipates that of the miner. Hence it is necessary to accept a general imperative of respect for ecological integrity. Onora O'Neill makes this point well:
The injustice of destroying natural and man-made environments can also be thought of in two ways. In the first place, their destruction is unjust because it is a further way by which others can be injured: systematic or gratuitous destruction of the means of life creates vulnerabilities, which facilitate direct injuries to individuals. … Secondly, the principle of destroying natural and man-made environments, in the sense of destroying their reproductive and regenerative powers, is not universalizable. (O'Neill 1996, p. 176)
In addition, the vulnerability that follows the destruction of integrity links this concept to environmental justice. The principle of integrity together with appropriate second order principles would ensure (a) the defense of the basic rights of humankind (Shue 1996) as well as (b) the support of environmental justice globally, because it would ensure the presence of the preconditions of agency and thus the ability of all humans to exercise their rights as agents (Gewirth 1982, Beyerveld and Brownsword 2001).
Ecological integrity is thus not an empty metaphor or a grand theory of little utility. It is a concept robust enough to support a solid ethical stance, one that reinstates humans in nature while respecting the latter, thus permitting clear answers in cases of conflicts between (present) economic human interests and (long-term) ecological concerns.
Ecological Integrity and the Law
It is reasonable to conceive of humanity as being morally responsible to protect the integrity of the whole ecosystem, and for that responsibility to be translated into such mechanisms as standard setting in a manner that is cognizant of ecological thresholds (Taylor 1998). Insofar as such responsibility is justified as a protection of human life and health, breaches of environmental regulations deserve not just economic penalties but criminal ones. Nevertheless there is a growing parallel movement to recognize the intrinsic value of both the components and the processes of natural systems, not only in philosophy (Westra 1998, Callicott 1987, Stone 1974, Leopold 1949), but also in the law (Brooks et al. 2002).
A number of international legal instruments also reflect the emerging global ecological concerns, and thus include language about respect for the intrinsic value of both natural entities and processes. This point is illustrated by a project involving the justices of the world's highest courts, which is funded by the United Nations Environment Programme (UNEP). The project's biocentric goal, as outlined by Judge Arthur Chaksalson of South Africa, is one of the most important results of the Johannesburg meeting (also known as "Rio+10"). The 2000 Draft International Covenant on Environment and Development incorporates the mandates of the Earth Charter, which was adopted by a United Nations Economic, Scientific, and Cultural Organization (UNESCO) resolution on October 16, 2003, in its language, and includes articles on ecological integrity and the intrinsic value of nature.
Although the positions advanced in these international initiatives are present in law, economic interests often obscure the opposition between the basic rights of persons and peoples and the property rights of legal entities and institutions. In the process courts tend to weigh these incommensurable values as though they were equal. But the right to life and the survival of peoples is not comparable to economic benefits or even the survival of corporate and industrial enterprises.
An additional connection arises from a consideration of ecological integrity a complex concept that, after several years of funded work, the Global Ecological Integrity Project eventually defined in 2000 (Westra et al. 2000). The protection of basic human rights through recognition of the need for ecological integrity, as Holmes Rolston (1993) acknowledges, is a step in the emerging awareness of humanity as an integral part of the biosphere (Westra 1998, Taylor 1998).
On the basis of the biocentric foundation for ecological integrity, it is necessary to move toward the twin goals of deterrence and restraint, as is done in the case of assaults, rapes, and other violent crimes. Laws that restrain unbridled property rights represent a first target; but efforts should not be limited to action within the realm of tort law. The reason is obvious: Economic harms are transferable, thus acceptable to the perpetrators of such harms, although the real harms produced are often incompensable. As Brooks and his colleagues indicate in reference to U.S. law, science is now available to support appeals to interdependence. "Not only has conservation biology as a discipline and biodiversity as a concept become an important part of national forest and endangered species management, but major court cases reviewing biodiversity determinations have been decided" (Brooks et al. 2002, p. 373). In addition, Earth System Science increasingly provides "multidisciplinary and interdisciplinary science framework for understanding global scale problems," including the relations and the functioning of "global systems that include the land, oceans and the atmosphere" (Brooks et al. 2002, p. 345). In essence, the ecosystem approach and systematic science of ecological integrity have contributed support to what Antonio A. Cançado Trindade terms "the globalization of human rights protection and of environmental protection" (Cançado Trindade 1992, p. 247).
As noted these ideals are contained in the language and the principles of the Earth Charter. The global reach of these ethics and charters, to be effective, must be supported by a supranational juridical entity such as the European Court of Human Rights. As the case for environmental or, better yet, ecological rights, becomes stronger and more accepted in the international law, the best solution as suggested by Patricia Birnie and Adam Boyle could be to empower the United Nations (UN). It might be desirable "to invest the UN Security Council, or some other UN organ with the power to act in the interests of 'ecological security,' taking universally binding decisions in the interests of all mankind and the environment (Birnie and Boyle 2002, p. 754). Empowering the United Nations in this way would foster support for programs based on the abundant evidence linking ecology and human rights and could become the basis for a new global environmental/human order (Westra 2004).
LAURA WESTRA
SEE ALSO Ecology;Research Integrity.
BIBLIOGRAPHY
Angermeier, Paul L., and James R. Karr. (1994). "Protecting Biotic Resources: Biological Integrity versus Biological Diversity as Policy Directives." BioScience 44(10): 690–697.
Beyleveld, Derek, and Roger Brownsword. (2001). Human Dignity in Bioethics and Biolaw. Oxford and New York: Oxford University Press.
Birnie, Patricia, W., and Adam E. Boyle. (2002). International Law and the Environment, 2nd edition. Oxford: Oxford University Press.
Brooks, Richard; Ross Jones; and Ross A. Virginia. (2002). Law and Ecology. Aldershot, Hants, UK: Ashgate Publishing.
Brunnée, Jutta. (1993). "The Responsibility of States for Environmental Harm in a Multinational Context—Problems and Trends." Les Cahiers de Droit 34: 827–845.
Brunnée, Jutta, and Stephen Toope. (1997). "Environmental Security and Freshwater Resources: Ecosystem Regime Building." American Journal of International Law 91: 26–59.
Cançado Trindade, Antonio A. (1992). "The Contribution of International Human Rights Law to Environmental Protection, with Special Reference to Global Environmental Change." In Environmental Change and International Law, ed. Edith Brown-Weiss. Tokyo: United Nations University Press.
Daily, Gretchen C., ed. (1997). Nature's Services: Societal Dependence on Natural Ecosystems. Washington, DC: Island Press.
Fidler, David, P. (2001). International Law and Public Health. Ardsley, NY: Transnational Publishers.
Gewirth, Alan. (1982). Human Rights Essays on Justification and Applications. Chicago: University of Chicago Press.
Hurrell, Andrew, and Benedict Kingsbury, eds. (1992). The International Politics of the Environment. New York: Oxford University Press.
Karr, James R. (1993). "Protecting Ecological Integrity: An Urgent Societal Goal." Yale Journal of International Law 18(1): 297–306.
Karr, James R. (1996). "Ecological Integrity and Ecological Health Are Not the Same." In Engineering Within Ecological Constraints, ed. Peter C. Schulze. Washington, DC: National Academy Press
Karr, James R. (2000). "Health, Integrity and Biological Assessment: The Importance of Whole Things." In Ecological Integrity: Integrating Environment, Conservation andHealth, ed. David Pimentel, Laura Westra, and Reed F. Noss. Washington, DC: Island Press.
Karr, James R. (2003). "Biological Integrity and Ecological Health." In Fundamentals of Ecotoxicology, 2nd edition, ed. Michael C. Newman and Michael A. Unger. Boca Raton, FL: CRC Press.
Karr, James, R., and Ellen W. Chu. (1999). Restoring Life in Running Waters. Washington, DC: Island Press.
Kiss, Alexandre Charles. (1992). "The Implications of Global Change for the International Legal System." In Environmental Change and International Law, ed. Edith Brown-Weiss. Tokyo: United Nations University Press.
Leopold, Aldo. (1949). A Sand County Almanac, and Sketches Here and There. New York: Oxford University Press.
Noss, Reed F. (1992). "The Wildlands Project: Land Conservation Strategy." Wild Earth, Special Issue: The Wildlife Project: 10–25.
Noss, Reed F., and Allen Y. Cooperrider. (1994). Saving Nature's Legacy: Protecting and Restoring Biodiversity. Washington, DC: Island Press.
O'Neill, Onora. (1996). Towards Justice and Virtue. Cambridge, MA: Cambridge University Press.
Pogge, Thomas. (2001). "Priority of Global Justice." In Global Justice, ed. Thomas Pogge. Oxford: Blackwell Publishers.
Rolston, Holmes, III. (1993). "Rights and Responsibilities on the Home Planet." Yale Journal of International Law 18(1): 251–275.
Shrader-Frechtte, Kristin. (1995). "Hard Ecology, Soft Ecology, and Ecosystem Integrity." In Perspectives on Ecological Integrity, ed. Laura Westra and John Lemons. Dordrecht, The Netherlands: Kluwer Academic Publishers.
Shrader-Frechette, Kristin, and Earl D. McCoy. (1993). Method in Ecology: Strategies for Conservation. New York: Cambridge University Press.
Shue, Henry. (1996). Basic Rights: Subsistence, Affluence and American Public Policy. Princeton, NJ: Princeton University Press.
Sterba, James. (1998). Justice Here and Now. Cambridge, MA: Cambridge University Press.
Stone, Christopher. (1974). Should Trees Have Standing?: Towards Legal Rights for Natural Objects. Los Altos, CA: W. Kaufmann.
Taylor, Prudence. (1998). "From Environmental to Ecological Human Rights: A New Dynamic in International Law?" Georgetown International Environmental Law Review 10: 309–397.
Westra, Laura. (1998). Living in Integrity Toward a Global Ethic to Restore a Fragmental Earth. Lanham, MD: Rowman and Littlefield.
Westra, Laura. (2000). "Institutionalized Violence and Human Rights." In Ecological Integrity: Integrating Environment, Conservation and Health, ed. David Pimentel, Laura Westra, and Reed F. Noss. Washington, DC: Island Press.
Westra, Laura. (2004). Ecoviolence and the Law (Supranational, Normative Foundations of Ecocrime). Ardsley, NY: Transnational Publishers, Inc.
Westra, Laura; Peter Miller; James R. Karr, et al. (2000). "Ecological Integrity and the Aims of the Global Ecological Integrity Project." In Ecological Integrity: Integrating Environment, Conservation and Health, ed. David Pimentel, Laura Westra, and Reed F. Noss. Washington, DC: Island Press.
INTERNET RESOURCE
Soskolne, Colin, and Roberto Bertollini. "Global Ecological Integrity and 'Sustainable Development': Cornerstones of Public Health." World Health Organization, Regional Office for Europe. Available from http://www.euro.who.int/document/gch/ecorep5.pdf.
Ecological Integrity
Ecological Integrity
Environmental stress is a challenge to ecological integrity
Components of ecological integrity
Indicators of ecological integrity
Ecological integrity is a relatively new concept that is being actively discussed by ecologists. However, a consensus has not yet emerged as to its definition. Clearly, human activities result in many environmental changes that enhance some species, ecosystems, and ecological processes, while at the same time causing important damage to others. The challenge for the concept of ecological integrity is to provide a means of distinguishing between responses that represent improvements in the quality of ecosystems, and those that are degradations.
The notion of ecological integrity is analogous to that of health. A healthy individual is relatively vigorous in his or her physical and mental capacities, and is uninfluenced by disease. Health is indicated by diagnostic symptoms that are bounded by ranges considered to be normal, and by attributes that are regarded as desirable. Unhealthy conditions are indicated by the opposite, and may require treatment to prevent further deterioration. However, the metaphor of human and ecosystem health is imperfect in some important respects, and has been criticized by ecologists. This is mostly because health refers to individual organisms, while ecological contexts are much more complex, involving many individuals of numerous species, and both living and nonliving attributes of ecosystems.
Environmental stress is a challenge to ecological integrity
Environmental stress refers to physical, chemical, and biological constraints on the productivity of species and the development of ecosystems. When they increase or decrease in intensity, stressors elicit ecological responses. Stressors can be natural environmental factors, or they can be associated with the activities of humans. Some environmental stressors are relatively local in their influence, while others are regional or global in scope. Stressors are challenges to ecological integrity.
Species and ecosystems have some capacity to tolerate changes in the intensity of environmental stressors, an attribute known as resistance. However, there are limits to resistance, which represent thresholds of tolerance. When these thresholds are exceeded, substantial ecological changes occur in response to further increases in the intensity of environmental stress.
Environmental stressors can be categorized as follows:
Physical stress
Physical stress refers to brief but intense events of kinetic energy. Because of its acute episodic nature, this is a type of disturbance. Examples include volcanic eruptions, windstorms, and explosions.
Wildfire
Wildfire is another disturbance, during which much of the biomass of an ecosystem combusts, and the dominant species may be killed.
Pollution
Pollution occurs when chemicals occur in concentrations large enough to affect organisms, and thereby cause ecological change. Toxic pollution can be caused by gases such as sulfur dioxide and ozone, elements such as mercury and arsenic, and pesticides. Nutrients such as phosphate and nitrate can distort ecological processes such as productivity, causing a type of pollution known as eutrophication.
Thermal stress
Thermal stress occurs when releases of heat cause ecological responses, as occurs near natural, hot water vents in the ocean, or with industrial discharges of heated water.
Radiation stress
Radiation stress is associated with excessive loads of ionizing energy. This can be important on mountaintops, where there are intense exposures to ultraviolet radiation, and in places where there are uncontrolled exposures to radioactive waste.
Climatic stress
Climatic stress is caused by excessive or insufficient regimes of temperature, moisture, solar radiation, or combinations of these. Tundra and deserts are climatically stressed ecosystems, while tropical rainforest occurs in places where climate is relatively benign.
Biological stress
Biological stress is associated with the complex interactions that occur among organisms of the same or different species. Biological stress can result from competition, herbivory, predation, parasitism, and disease. The harvesting and management of species and ecosystems by humans is a type of biological stress.
Large changes in the intensity of environmental stress result in various types of ecological responses. For example, when an ecosystem is disrupted by an intense disturbance, there may be substantial mortality of its species and other damage, followed by recovery through succession. In contrast, a longer-term intensification of environmental stress, possibly associated with chronic pollution or climate change, causes more permanent ecological adjustments to occur. Relatively vulnerable species are reduced in abundance or eliminated from sites that are stressed over the longer term, and their modified niches are assumed by organisms that are more tolerant. Other common responses include a simplification of species richness, and decreased rates of productivity, decomposition, and nutrient cycling. These changes represent an ecological conversion, or a longer-term change in the character of the ecosystem.
Components of ecological integrity
Many studies have been made of the ecological responses to disturbance and to longer-term changes in the intensity of environmental stress. These studies have examined stressors associated with, for example, pollution, the harvesting of species from ecosystems, and the conversion of natural ecosystems into managed agroecosystems. The commonly observed patterns of change in these sorts of stressed ecosystems are considered to represent some of the key elements of ecological integrity. Such observations can be used to develop indicators of ecological integrity, which are useful in determining whether this condition is improving or being degraded over time. It has been suggested that greater ecological integrity is displayed by systems with the following characteristics:
Resiliency and resistance
Ecosystems with greater ecological integrity are, in a relative sense, more resilient and resistant to changes in the intensity of environmental stress. In the ecological context, resistance refers to the capacity of organisms, populations, and communities to tolerate increases in stress without exhibiting significant responses. Resistance is manifest in thresholds of tolerance. Resilience refers to the ability to recover from disturbance.
Biodiversity
In its simplest interpretation, biodiversity refers to the number of species in some ecological community or designated area, such as a park or a country. However, biodiversity is better defined as the total richness of biological variation, including genetic variation within populations and species, the numbers of species in communities, and the patterns and dynamics of these over large areas.
Complexity of structure and function
The structural and functional complexity of ecosystems is limited by natural environmental stresses associated with climate, soil, chemistry, and other factors, and by stressors associated with human activities. As the overall intensity of stress increases or decreases, structural and functional complexity responds accordingly. Under any particular environmental regime, older ecosystems will generally be more complex than younger ecosystems.
Presence of large species
The largest, naturally occurring species in any ecosystem generally appropriate relatively large amounts of resources, occupy a great deal of space, and require large areas to sustain their populations. In addition, large species are usually long-lived, and therefore integrate the effects of stressors over an extended time. Consequently, ecosystems that are subject to an intense regime of environmental stress cannot support relatively large species. In contrast, mature ecosystems of relatively benign environments are dominated by large, long-lived species.
Presence of higher-order predators
Because top predators are dependent on a broad base of ecological productivity, they can only be sustained by relatively extensive and/or productive ecosystems.
Controlled nutrient cycling
Recently disturbed ecosystems temporarily lose some of their capability to exert biological control over nutrient cycling, and they often export large quantities of nutrients dissolved or suspended in stream water. Systems that do not “leak” their nutrient capital in this way are considered to have greater ecological integrity.
Efficient energy use and transfer
Large increases in environmental stress commonly result in community respiration exceeding productivity, so that the standing crop of biomass decreases. Ecosystems that do not degrade their capital of bio-mass are considered to have greater integrity than those in which biomass is decreasing over time.
Ability to maintain natural ecological values
Ecosystems that can naturally maintain their species, communities, and other important characteristics, without interventions by humans through management, have greater ecological integrity. For example, if a rare species of animal can only be sustained through intensive management of its habitat by humans, or by management of its demographics, possibly by a captive breeding and release program, then its populations and ecosystem are lacking in ecological integrity.
Components of a “natural” community
Ecosystems that are dominated by nonnative introduced species are considered to have less ecological integrity than those composed of native species.
The last two indicators involve judgments about “naturalness” and the role of humans in ecosystems, which are philosophically controversial topics. However, most ecologists consider that self-organizing unmanaged ecosystems have greater ecological integrity than those that are strongly influenced by human activities. Examples of the latter include agroecosystems, forestry plantations, and urban and suburban ecosystems. None of these systems can maintain themselves in the absence of large inputs of energy, nutrients, and physical management by humans.
Indicators of ecological integrity
Indicators of ecological integrity vary widely in their scale, complexity, and intent. For example, certain metabolic indicators can suggest the responses by individual organisms and populations to toxic stress, as is the case of assays of detoxifying enzyme systems
KEY TERMS
Stress— Environmental constraints that cause ecological disruptions (disturbances) or that limit the potential productivity of species or the development of ecosystems. Environmental stress is a challenge to ecological integrity.
that respond to exposure to persistent chlorinated hydrocarbons, such as DDT and PCBs. Indicators related to populations of endangered species are relevant to the viability of those species, as well as the integrity of their natural communities. There are also indicators relevant to processes occurring at the level of landscape. There are even global indicators relevant to climate change, such as depletion of stratospheric ozone and deforestation.
Sometimes, relatively simple indicators can be used to integrate the ecological integrity of a large and complex ecosystem. In the western United States, for instance, the viability of populations of spotted owls(Strix occidentalis) is considered to be an indicator of the integrity of the types of old-growth forest in which this endangered bird breeds. If plans to harvest and manage those forests are judged to pose a threat to the viability of a population of spotted owls or the species, this would indicate a significant challenge to the integrity of the entire old-growth forest ecosystem.
Ecologists are also developing holistic indicators of ecological integrity. These are designed as composites of various indicators, analogous to certain economic indices such as the Dow-Jones Index of the stock market, the Consumer Price Index, and gross domestic product indices of economies. Composite economic indicators like these are relatively simple to design because all of the input data are measured in a common way, for example, in dollars. However, in ecology there is no common currency among the various indicators of ecological integrity, and it is therefore difficult to develop composite indicators that people will agree upon.
In spite of the difficulties, ecologists are making progress in their development of indicators of ecological integrity. This is an important activity, because people and their larger society need objective information about changes in the integrity of species and ecosystems so that actions can be taken to prevent unacceptable degradations. It is being increasingly recognized that human economies can only be sustained over the longer term by ecosystems with integrity. These must be capable of supplying continuous flows of renewable resources, such as trees, fish, agricultural products, and clean air and water. There are also important concerns about the intrinsic value of native species and their natural ecosystems, all of which must be sustained along with humans. A truly sustainable economy can only be based on ecosystems with integrity.
See also Indicator species; Stress, ecological.
Resources
BOOKS
Babaev, Agadzhan, and Agajan G. Babaev, eds. Desert Problems and Desertification in Central Asia: The Researches of the Desert Institute. Berlin: Springer Verlag, 1999.
Freedman, B. Environmental Ecology. 2nd ed. San Diego: Academic Press, 1995.
Hamblin, W.K., and Christiansen, E.H. Earth’s Dynamic Systems. 9th ed. Upper Saddle River: Prentice Hall, 2001.
Woodley, S., J. Kay, and G. Francis, eds. Ecological Integrity and the Management of Ecosystems. Boca Raton, FL: St. Lucie Press, 1993.
PERIODICALS
Caballero A., and M.A. Toro. “Interrelations Between Effective Population Size and Other Pedigree Tools for the Management of Conserved Populations.” Genet Res 75, no. 3 (June 2000): 331-343.
Karr, J. “Defining and Assessing Ecological Integrity: Beyond Water Quality.” Environmental Toxicology and Chemistry 12 (1993): 1521-1531.
OTHER
Parks Canada. “What Is Ecological Integrity?” <http://www.pc.gc.ca/progs/np-pn/eco_integ/index_E.asp> (accessed November 16, 2006).
U.S. Environmental Protection Agency. “Bioindicators for Assessing Ecological Integrity of Prairie Wetlands” <http://www.epa.gov/owow/wetlands/wqual/ppaindex.html> (accessed November 21, 2006).
Bill Freedman
Ecological Integrity
Ecological integrity
Ecological integrity is a relatively new concept that is being actively discussed by ecologists. However, a consensus has not yet emerged as to the definition of ecological integrity. Clearly, human activities result in many environmental changes that enhance some species , ecosystems, and ecological processes, while at the same time causing important damage to others. The challenge for the concept of ecological integrity is to provide a means of distinguishing between responses that represent improvements in the quality of ecosystems, and those that are degradations.
The notion of ecological integrity is analogous to that of health. A healthy individual is relatively vigorous in his or her physical and mental capacities, and is uninfluenced by disease . Health is indicated by diagnostic symptoms that are bounded by ranges considered to be normal, and by attributes that are regarded as desirable. Unhealthy conditions are indicated by the opposite, and may require treatment to prevent further deterioration. However, the metaphor of human and ecosystem health is imperfect in some important respects, and has been criticized by ecologists. This is mostly because health refers to individual organisms, while ecological contexts are much more complex, involving many individuals of numerous species, and both living and nonliving attributes of ecosystems.
Environmental stress is a challenge to ecological integrity
Environmental stress refers to physical, chemical, and biological constraints on the productivity of species and the development of ecosystems. When they increase or decrease in intensity, stressors elicit ecological responses. Stressors can be natural environmental factors, or they can be associated with the activities of humans. Some environmental stressors are relatively local in their influence, while others are regional or global in scope. Stressors are challenges to ecological integrity.
Species and ecosystems have some capacity to tolerate changes in the intensity of environmental stressors, an attribute known as resistance. However, there are limits to resistance, which represent thresholds of tolerance. When these thresholds are exceeded, substantial ecological changes occur in response to further increases in the intensity of environmental stress.
Environmental stressors can be categorized as follows:
Physical stress
Physical stress refers to brief but intense events of kinetic energy . Because of its acute, episodic nature, this is a type of disturbance. Examples include volcanic eruptions, windstorms, and explosions.
Wildfire
Wildfire is another disturbance, during which much of the biomass of an ecosystem combusts, and the dominant species may be killed.
Pollution
Pollution occurs when chemicals occur in concentrations large enough to affect organisms, and thereby cause ecological change to occur. Toxic pollution can be caused by gases such as sulfur dioxide and ozone , elements such as mercury and arsenic, and pesticides . Nutrients such as phosphate and nitrate can distort ecological processes such as productivity, causing a type of pollution known as eutrophication .
Thermal stress
Thermal stress occurs when releases of heat cause ecological responses, as occurs near natural, hot water vents in the ocean , or with industrial discharges of heated water.
Radiation stress
Radiation stress is associated with excessive loads of ionizing energy. This can be important on mountain-tops, where there are intense exposures to ultraviolet radiation, and in places where there are uncontrolled exposures to radioactive waste .
Climatic stress
Climatic stress is caused by excessive or insufficient regimes of temperature , moisture, solar radiation, or combinations of these. Tundra and deserts are climatically stressed ecosystems, while tropical rainforest occurs in places where climate is relatively benign.
Biological stress
Biological stress is associated with the complex interactions that occur among organisms of the same or different species. Biological stress can result from competition , herbivory, predation, parasitism, and disease. The harvesting and management of species and ecosystems by humans is a type of biological stress.
Large changes in the intensity of environmental stress result in various types of ecological responses. For example, when an ecosystem is disrupted by an intense disturbance, there may be substantial mortality of its species and other damage, followed by recovery through succession . In contrast, a longer-term intensification of environmental stress, possibly associated with chronic pollution or climate change, causes more permanent ecological adjustments to occur. Relatively vulnerable species are reduced in abundance or eliminated from sites that are stressed over the longer term, and their modified niches are assumed by organisms that are more tolerant. Other common responses include a simplification of species richness, and decreased rates of productivity, decomposition , and nutrient cycling. These changes represent an ecological conversion, or a longer-term change in the character of the ecosystem.
Components of ecological integrity
Many studies have been made of the ecological responses to disturbance and to longer-term changes in the intensity of environmental stress. These studies have examined stressors associated with, for example, pollution, the harvesting of species from ecosystems, and the conversion of natural ecosystems into managed agroecosystems. The commonly observed patterns of change in these sorts of stressed ecosystems are considered to represent some of the key elements of ecological integrity. Such observations can be used to develop indicators of ecological integrity, which are useful in determining whether this condition is improving or being degraded over time. It has been suggested that greater ecological integrity is displayed by systems with the following characteristics:
Resiliency and resistance
Ecosystems with greater ecological integrity are, in a relative sense, more resilient and resistant to changes in the intensity of environmental stress. In the ecological context, resistance refers to the capacity of organisms, populations, and communities to tolerate increases in stress without exhibiting significant responses. Resistance is manifest in thresholds of tolerance. Resilience refers to the ability to recover from disturbance.
Biodiversity
In its simplest interpretation, biodiversity refers to the number of species occurring in some ecological community or in a designated area, such as a park or a country. However, biodiversity is better defined as the total richness of biological variation, including genetic variation within populations and species, the numbers of species in communities, and the patterns and dynamics of these over large areas.
Complexity of structure and function
The structural and functional complexity of ecosystems is limited by natural environmental stresses associated with climate, soil , chemistry , and other factors, and by stressors associated with human activities. As the overall intensity of stress increases or decreases, structural and functional complexity responds accordingly. Under any particular environmental regime, older ecosystems will generally be more complex than younger ecosystems.
Presence of large species
The largest, naturally occurring species in any ecosystem generally appropriate relatively large amounts of resources, occupy a great deal of space , and require large areas to sustain their populations. In addition, large species are usually long-lived, and therefore integrate the effects of stressors over an extended time. Consequently, ecosystems that are subject to an intense regime of environmental stress cannot support relatively large species. In contrast, mature ecosystems of relatively benign environments are dominated by large, long-lived species.
Presence of higher-order predators
Because top predators are dependent on a broad base of ecological productivity , they can only be sustained by relatively extensive and/or productive ecosystems.
Controlled nutrient cycling
Recently disturbed ecosystems temporarily lose some of their capability to exert biological control over nutrient cycling, and they often export large quantities of nutrients dissolved or suspended in streamwater. Systems that are not "leaky" of their nutrient capital in this way are considered to have greater ecological integrity.
Efficient energy use and transfer
Large increases in environmental stress commonly result in community respiration exceeding productivity, so that the standing crop of biomass decreases. Ecosystems that are not degrading in their capital of biomass are considered to have greater integrity than those in which biomass is decreasing over time.
Ability to maintain natural ecological values
Ecosystems that can naturally maintain their species, communities, and other important characteristics, without interventions by humans through management, have greater ecological integrity. For example, if a rare species of animal can only be sustained through intensive management of its habitat by humans, or by management of its demographics, possibly by a captive-breeding and release program, then its populations and ecosystem are lacking in ecological integrity.
Components of a "natural" community
Ecosystems that are dominated by non-native, introduced species are considered to have less ecological integrity than those composed of native species.
The last two indicators involve judgements about "naturalness" and the role of humans in ecosystems, which are philosophically controversial topics. However, most ecologists would consider that self-organizing, unmanaged ecosystems have greater ecological integrity than those that are strongly influenced by human activities. Examples of the latter include agroecosystems, forestry plantations, and urban and suburban ecosystems. None of these systems can maintain themselves in the absence of large inputs of energy, nutrients, and physical management by humans.
Indicators of ecological integrity
Indicators of ecological integrity vary widely in their scale, complexity, and intent. For example, certain metabolic indicators can suggest the responses by individual organisms and populations to toxic stress, as is the case of assays of detoxifying enzyme systems that respond to exposure to persistent chlorinated hydrocarbons , such as DDT and PCBs. Indicators related to populations of endangered species are relevant to the viability of those species, as well as the integrity of their natural communities. There are also indicators relevant to processes occurring at the level of landscape. There are even global indicators, for example, relevant to climate change, depletion of stratospheric ozone, and deforestation .
Sometimes, relatively simple indicators can be used to integrate the ecological integrity of a large and complex ecosystem. In the western United States, for instance, the viability of populations of spotted owls (Strix occidentalis) is considered to be an indicator of the integrity of the types of old-growth forest in which this endangered bird breeds. If plans to harvest and manage those forests are judged to pose a threat to the viability of a population of spotted owls or the species, this would indicate a significant challenge to the integrity of the entire old-growth forest ecosystem.
Ecologists are also beginning to develop holistic indicators of ecological integrity. These are designed as composites of various indicators, analogous to certain economic indices such as the Dow-Jones Index of the stock market, the Consumer Price Index, and gross domestic product indices of economies. Composite economic indicators like these are relatively simple to design because all of the input data are measured in a common way, for example, in dollars. However, in ecology there is no common currency among the various indicators of ecological integrity, and it is therefore difficult to develop composite indicators that people will agree upon.
In spite of the difficulties, ecologists are making progress in their development of indicators of ecological integrity. This is an important activity for ecologists, because people and their larger society need objective information about changes in the integrity of species and ecosystems so that actions can be taken to prevent unacceptable degradations. It is being increasingly recognized that human economies can only be sustained over the longer term by ecosystems with integrity. These must be capable of supplying continuous flows of renewable resources, such as trees, fish , agricultural products, and clean air and water. There are also important concerns about the intrinsic value of native species and their natural ecosystems, all of which must be sustained along with humans. A truly sustainable economy can only be based on ecosystems with integrity.
See also Indicator species; Stress, ecological.
Resources
books
Babaev, Agadzhan, and Agajan G. Babaev, eds. Desert Problems and Desertification in Central Asia: The Researches of the Desert Institute. Berlin: Springer Verlag, 1999.
Freedman, B. Environmental Ecology. 2nd ed. San Diego: Academic Press, 1995.
Hamblin, W. K., and E.H. Christiansen. Earth's Dynamic Systems. 9th ed. Upper Saddle River: Prentice Hall, 2001.
Woodley, S., J. Kay, and G. Francis, eds. Ecological Integrity and the Management of Ecosystems. Boca Raton, FL: St. Lucie Press, 1993.
periodicals
Caballero, A., and M. A. Toro. "Interrelations Between Effective Population Size and Other Pedigree Tools for the Management of Conserved Populations." Genetical Research 75, no. 3 (June 2000): 331-43.
Karr, J. "Defining and Assessing Ecological Integrity: Beyond Water Quality." Environmental Toxicology and Chemistry 12 (1993): 1521-1531.
Bill Freedman
KEY TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .- Stress
—Environmental constraints that cause ecological disruptions (that is, disturbance) or that limit the potential productivity of species or the development of ecosystems. Environmental stress is a challenge to ecological integrity.
Ecological Integrity
Ecological integrity
Ecological (or biological) integrity is a measure of how intact or complete an ecosystem is. Ecological integrity is a relatively new and somewhat controversial notion, however, which means that it cannot be defined exactly. Human activities cause many changes in environmental conditions, and these can benefit some species , communities, and ecological processes, while causing damages to others at the same time. The notion of ecological integrity is used to distinguish between ecological responses that represent improvements, and those that are degradations.
Challenges to ecological integrity
Ecological integrity is affected by changes in the intensity of environmental stressors. Environmental stressors can be defined as physical, chemical, and biological constraints on the productivity of species and the processes of ecosystem development. Many environmental stressors are associated with the activities of humans, but some are also natural factors. Environmental stressors can exert their influence on a local scale, or they may be regional or even global in their effects. Stressors represent environmental challenges to ecological integrity.
Environmental stressors are extremely complex, but they can be categorized in the following ways:
(1) Physical stressors are associated with brief but intense exposures to kinetic energy. Because of its acute, episodic nature, this represents a type of disturbance. Examples include volcanic eruptions, windstorms, and explosions; (2) Wildfire is another kind of disturbance, characterized by the combustion of much of the biomass of an ecosystem, and often the deaths of the dominant plants; (3) Pollution occurs when chemicals are present in concentrations high enough to affect organisms and thereby cause ecological changes. Toxic pollution may be caused by such gases as sulfur dioxide and ozone , metals such as mercury and lead , and pesticides. Nutrients such as phosphate and nitrate can affect ecological processes such as productivity, resulting in a type of pollution known as eutrophication; (4) Thermal stress occurs when releases of heat to the environment cause ecological changes, as occurs near natural hot-water vents in the ocean, or where there are industrial discharges of warmed water; (5) Radiation stress is associated with excessive exposures to ionizing energy. This is an important stressor on mountaintops because of intense exposures to ultraviolet radiation , and in places where there are uncontrolled exposures to radioactive wastes; (6) Climatic stressors are associated with excessive or insufficient regimes of temperature, moisture, solar radiation, and combinations of these. Tundra and deserts are climatically stressed ecosystems, while tropical rain forests occur in places where the climatic regime is relatively benign; (7) Biological stressors are associated with the complex interactions that occur among organisms of the same or different species. Biological stresses result from competition , herbivory, predation, parasitism, and disease. The harvesting and management of species and ecosystems by humans can be viewed as a type of biological stress.
All species and ecosystems have a limited capability for tolerating changes in the intensity of environmental stressors. Ecologists refer to this attribute as resistance . When the limits of tolerance to environmental stress are exceeded, however, substantial ecological changes are caused.
Large changes in the intensity of environmental stress result in various kinds of ecological responses. For example, when an ecosystem is disrupted by an intense disturbance, there will be substantial mortality of some species and other damages. This is followed by recovery of the ecosystem through the process of succession . In contrast, a longer-term intensification of environmental stress, possibly caused by chronic pollution or climate change, will result in longer lasting ecological adjustments. Relatively vulnerable species become reduced in abundance or are eliminated from sites that are stressed over the longer term, and their modified niches will be assumed by more tolerant species. Other common responses of an intensification of environmental stress include a simplification of species richness, and decreased rates of productivity, decomposition , and nutrient cycling. These changes represent a longer-term change in the character of the ecosystem.
Components of ecological integrity
Many studies have been made of the ecological responses to both disturbance and to longer-term changes in the intensity of environmental stressors. Such studies have, for instance, examined the ecological effects of air or water pollution , of the harvesting of species or ecosystems, and the conversion of natural ecosystems into managed agroecosystems. The commonly observed patterns of change in stressed ecosystems have been used to develop indicators of ecological integrity, which are useful in determining whether this condition is improving or being degraded over time. It has been suggested that greater ecological integrity is displayed by systems that, in a relative sense: (1) are resilient and resistant to changes in the intensity of environmental stress. Ecological resistance refers to the capacity of organisms, populations, or communities to tolerate increases in stress without exhibiting significant responses. Once thresholds of tolerance are exceeded, ecological changes occur rapidly. Resilience refers to the ability to recover from disturbance; (2) are biodiverse. Biodiversity is defined as the total richness of biological variation, including genetic variation within populations and species, the numbers of species in communities, and the patterns and dynamics of these over large areas; (3) are complex in structure and function. The complexity of the structural and functional attributes of ecosystems is limited by natural environmental stresses associated with climate, soil , chemistry, and other factors, and also by stressors associated with human activities. As the overall intensity of stress increases or decreases, structural and functional complexity responds accordingly. Under any particular environmental regime, older ecosystems will generally be more complex than younger ecosystems; (4) have large species present. The largest species in any ecosystem appropriate relatively large amounts of resources, occupy a great deal of space, and require large areas to sustain their populations. In addition, large species tend to be long-lived, and consequently they integrate the effects of stressors over an extended time. As a result, ecosystems that are affected by intense environmental stressors can only support a few or no large species. In contrast, mature ecosystems occurring in a relatively benign environmental regime are dominated by large, long-lived species; (5) have higher-order predators present. Top predators are sustained by a broad base of ecological productivity , and consequently they can only occur in relatively extensive and/or productive ecosystems; (6) have controlled nutrient cycling. Ecosystems that have recently been disturbed lose some of their biological capability for controlling the cycling of nutrients, and they may lose large amounts of nutrients dissolved or suspended in stream water. Systems that are not "leaky" of their nutrient capital are considered to have greater ecological integrity; (7) are efficient in energy use and transfer. Large increases in environmental stress commonly result in community-level respiration exceeding productivity, resulting in a decrease in the standing crop of biomass in the system. Ecosystems that are not losing their capital of biomass are considered to have greater integrity than those in which biomass is decreasing over time; (8) have an intrinsic capability for maintaining natural ecological values. Ecosystems that can naturally maintain their species, communities, and other important characteristics, without being managed by humans, have greater ecological integrity. If, for example, a population of a rare species can only be maintained by management of its habitat by humans, or by a program of captive-breeding and release, then its population, and the ecosystem of which it is a component, are lacking in ecological integrity; (9) are components of a "natural" community. Ecosystems that are dominated by non-native, introduced species are considered to have less ecological integrity than ecosystems composed of indigenous species.
Indicators (8) and (9) are related to "naturalness" and the roles of humans in ecosystems, both of which are philosophically controversial topics. However, most ecologists would consider that self-organizing, unmanaged ecosystems composed of native species have greater ecological integrity than those that are strongly influenced by humans. Examples of strongly human-dominated systems include agroecosystems, forestry plantations, and urban and suburban areas. None of these ecosystems can maintain their character in the absence of management by humans, including large inputs of energy and nutrients.
Indicators of ecological integrity
Indicators of ecological integrity vary greatly in their intent and complexity. For instance, certain metabolic indicators have been used to monitor the responses by individuals and populations to toxic stressors, as when bioassays are made of enzyme systems that respond vigorously to exposures to dichlorodiphenyl-trichloroethane (DDT), pentachlorophenols (PCBs), and other chlorinated hydrocarbons . Other simple indicators include the populations of endangered species ; these are relevant to the viability of those species as well as the integrity of the ecosystem of which they are a component. There are also indicators of ecological integrity at the level of landscape, and even global indicators relevant to climate change, depletion of stratospheric ozone, and deforestation .
Relatively simple indicators can sometimes be used to monitor the ecological integrity of extensive and complex ecosystems. For example, the viability of populations of spotted owls (Strix occidentalis )is considered to be an indicator of the integrity of the old-growth forests in which this endangered species breeds in the western United States. These forests are commercially valuable, and if plans to harvest and manage them are judged to threaten the viability of a population of spotted owls, this would represent an important challenge to the integrity of the old-growth forest ecosystem.
Ecologists are also beginning to develop composite indicators of ecological integrity. These are designed as summations of various indicators, and are analogous to such economic indices such as the Dow-Jones Index of stock markets, the Consumer Price Index, and the gross domestic product of an entire economy. Composite economic indicators of this sort are relatively simple to design, because all of the input data are measured in a common way (for example, in dollars). In ecology , however, there is no common currency among the many indicators of ecological integrity. Consequently it is difficult to develop composite indicators that ecologists will agree upon.
Still, some research groups have developed composite indicators of ecological integrity that have been used successfully in a number of places and environmental contexts. For instance, the ecologist James Karr and his co-workers have developed composite indicators of the ecological integrity of aquatic ecosystems, which are being used in modified form in many places in North America.
In spite of all of the difficulties, ecologists are making substantial progress in the development of indicators of ecological integrity. This is an important activity, because our society needs objective information about complex changes that are occurring in environmental quality, including degradations of indigenous species and ecosystems. Without such information, actions may not be taken to prevent or repair unacceptable damages that may be occurring.
Increasingly, it is being recognized that human economies can only be sustained over the longer term by ecosystems with integrity. Ecosystems with integrity are capable of supplying continuous flows of such renewable resources as timber, fish, agricultural products, and clean air and water. Ecosystems with integrity are also needed to sustain populations of native species and their natural ecosystems, which must be sustained even while humans are exploiting the resources of the biosphere .
[Bill Freedman Ph.D. ]
RESOURCES
BOOKS
Freedman, B. Environmental Ecology, 2nd ed. San Diego: Academic Press, 1995.
Woodley, S., J. Kay, and G. Francis, eds. Ecological Integrity and the Management of Ecosystems. Boca Raton, FL: St. Lucie Press, 1993.
PERIODICALS
Karr, J. "Defining and assessing ecological integrity: Beyond water quality." Environmental Toxicology and Chemistry 12 (1993): 1521-1531.