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If we are to be stewards of the ecological systems that make up our biosphere, then we must have some state, in which we wish these systems to be. The term 'integrity' has become the name we use for this state. Environmental managers finds themselves mandated by various policy statements and legislation (the Great Lakes Water Quality Agreement, 1978, the Canada Park Service Act, 1988, the draft Montana Environmental Protection Act, 1992, Environment Canada's mission statement, 1992) to preserve/maintain/promote/protect/restore ecological integrity. The challenge now is to define 'integrity'.

Regier, in his chapter, explores the notion of integrity. For some, at first glance, his exploration will seem too abstract and imprecise to be helpful in the 'real world'. In essence, he says that a system has ecological integrity when it is perceived to be a whole that is in a state of 'well being'. He explores what this means for different groups of people, in different situations, with different perspectives. This definition is as specific as a general definition of ecological integrity can be. Our sense of what constitutes ecological integrity is very much dependant on our perspective of what constitutes a whole ecological system. When we are dealing with ecological systems, we are dealing with complex systems, systems which require complex descriptions that are case specific. Simple answers, definitions and hypotheses (like species diversity leads to ecological stability) are never adequate for discussing complex systems and, by implication, ecological integrity.

This is not to say that there are no generic statements to be made. King, in his chapter, acquaints us with many of the lessons to be learned from complex systems theory with regard to the issues that must always be of concern, in any inquiry into ecological integrity. If ecological integrity refers to our sense of the wholeness and well being of an ecological system then our assessment of integrity should begin with an analysis of the system we are examining.

Systems analysis always begins by considering spatial and temporal scale and hierarchy. Are we concerned with the integrity of a landscape, a forest, a particular species or all of these? Over what time scale and what spatial extent? What are the important processes which make up the system? To answer these questions, as King discusses, is to define the perspective we are taking on, to separate the things which we deem important from those we think unimportant.

One of the lessons of systems theory is that there is no preferred observer. Thus we must be careful to explicitly specify the system, (i.e. identify scale, hierarchy, boundaries, system environment, etc.) because part of this process is the identification of the issues of importance, that is the contextual perspective for the integrity evaluation. Neglecting this step will implicitly impose a perspective, including a set of values, on the integrity evaluation. A consequence of this is that the contextual issues will not be thought through, and will be implicitly assumed. The issues of importance and relevance will not be explicitly identified and the experience of systems theory tells us that they will likely be neglected.

Furthermore, specifying the system means identifying not only the physical and biological issues that scientists feel are important- and given the state of the science of ecology, there is much debate about these (Kay, 1991b)- but also identifying the important socio-economic, political and policy issues. Several authors in this volume (Regier, King, Steedman and Haider, Munn, and Marshall et al.) have noted that it is crucial to explicitly include societal issues and values in any evaluation of ecological integrity. Otherwise the evaluation will only reflect the values and concerns of the evaluator, and as such is likely to have little meaning, or be of little use, to policy and decision makers (who must represent a broad group of stakeholders).

Many environmental managers are reluctant to include societal issues and values in an evaluation of ecological integrity. As Steedman and Haider point out, their training is usually in the physical and biological sciences, a training which instills a reluctance to sully any analysis with fuzzy, subjective, qualitative issues, as this would only serve to dilute the 'objectivity' of science with the subjectivity of values. However, reality is that when one specifies systems, one is not dealing with objective science, but with perspectives, with ways of looking at the world, and these always reflect a value system. We must acknowledge this reality and make it front and center in our evaluations of integrity. This theme echoes throughout this book-- that a discussion of ecological integrity without a discussion of the social, economic, political and policy concerns is not a meaningful discussion.

So where does this leave us? It is not surprising, in light of this discussion, that attempts to develop general criteria for evaluating, and thereby defining, ecological integrity have not been successful. Clearly, integrity is context specific, the context being the physical, biological, social and cultural features of the specific geographic area in question. Furthermore, an evaluation of integrity must look at issues from different hierarchical and scale perspectives. Thus, integrity can only be defined clearly (in terms of evaluative criteria) for specific ecosystems, in the context of the humans which are an integral part of the ecosystem. In no way does this detract from the concept of integrity. This is just the reality of dealing with complex systems.

Furthermore, evaluating and defining ecological integrity can never be seen as purely an exercise in the physical and biological sciences. Ecological integrity is about our sense of the wholeness and well being of ecological systems and in this must reflect our sense of what we value in them.

So what is the role of the physical and biological sciences in discussing ecological integrity? Serafin and Steedman in their working group report (for this workshop) address this:

"Meaningful discussion of ecological integrity must be tempered by the realization that the concept does not exist outside of human value judgements, unlike notions such as gravity or general relativity. Measurements of integrity by scientific means are therefore limited to criteria which are subjectively selected, even though those criteria are frequently paraded as objective and value-free. Can the methods of measuring integrity be scientific even though the underlying premise is not? The nature of the dilemma is glaring if we consider a question like: Did the Mount St. Helens or the Krakatoa events cause an impairment of ecological integrity? If we say no, implying that nature can do no wrong, we have made a definite value judgement. Conversely, arguing that the biotic aspect of the ecosystem was degraded invites a rebuttal built around forest fires, floods, or other dramatic stochastic events. And again we have made a value judgement. Therefore, it seems apparent that we can measure and analyze CHANGES in an ecosystem, but we can only make JUDGEMENTS about the integrity of that system."

Complex systems have multiple steady states. Thus in a specific geographical location there is the potential for a number of different ecosystems, communities and species to exist, in addition to the ones currently present. It is possible that such systems may only be dynamically stable, that is a stable equilibrium point does not exist for the system. Holling (1986, 1992) gives a number of examples of this and suggests that the notion of a steady state is really an illusion. Ecosystems are continually undergoing a birth-growth-maturity death process which he refers to as an exploitation, conservation, release, reorganization cycle. Interrupting this cycle, through for example forest fire suppression, not only interferes with the normal cycle of life but also magnifies the magnitude of changes when they are eventually triggered.

Movement through the cyclic process, described by Holling, is not continuous. There are temporary stationary states. The process is often characterized by bifurcations and flips, that is, catastrophic behaviour. Furthermore, elements of the process can be chaotic, that is inherently unpredictable. I have explored the implications of these behaviours for ecosystem integrity elsewhere (Kay 1991a). The main point of this work is that the normal behaviour of ecological systems is quite complex and the simple notion of succession to a stable climax community is not sufficient. Nor is the notion that loss of ecological integrity corresponds to disturbance of the ecosystem away from a climax. Life is not about maintaining stable equilibrium states. It is dynamic and ever-changing.

The challenge facing us is to discover what rules, if any, govern the overall direction of ecosystem development and ecosystem reorganization induced by environmental change. Ecosystems exhibit chaotic and catastrophic behaviour and this, combined with the inherent variability in their organizational processes, means that we will always have uncertainty about their dynamic behaviour. Ecological systems belong to a class of systems Weinberg refers to as middle number systems. The main issue is to discover what constraints, if any, there are on the behaviour of these systems. Is there an overall direction to development and reorganization in response to environmental change? How can development be characterized? Can we decrease our uncertainty about developmental and reorganization processes and by how much?

Currently there are a number of investigators working on these issues. (See Gunther and Folke, 1992 for a review.) We (Schneider and Kay, 1993) have proposed a non-equilibrium thermodynamic basis for understanding, as self-organizing phenomena, ecosystem development and response to environmental change. The development of self-organizing systems is characterized by periods of rapid organization followed by an interval during which the system maintains itself in a steady state. Organization of the system is not a smooth process but rather proceeds in spurts. Each spurt results in the system moving further from equilibrium, dissipating more energy, and becoming more organized. Ecosystem succession is an example of this kind of process. Each of the seral stages corresponds to one steady-state plateau. The displacement of a previous seral stage by the next is an example of a spurt, the re-organization of the system to a new level of structure which dissipates more energy.

As ecosystems develop they become more organized and effective at dissipating solar energy (Kay, 1984). But these self-organizing tendencies are limited by external environmental fluctuations that tend to disorganize ecosystems. The point in state space where the disorganizing forces of external environmental change and the organizing thermodynamic forces are balanced is referred to as the 'optimum operating point'. The climax community in ecological succession would be an example of an ecosystem's optimum operating point. The climax community represents a temporary balance between the organizing and the disorganizing forces in ecosystems.

Our sense of the system as a whole, that is its integrity, has to do with its ability to maintain its organization and to continue its process of self-organization. If a system is unable to maintain its organization, in the face of changing environmental conditions, then it has lost its integrity. In essence integrity has to do with the ability of the system to attain and maintain its optimum operating point.

Integrity, that is our sense of an ecosystem as a whole, encompasses three major ecosystem organizational facets. Ecosystem health, the ability to maintain an optimum operating point under normal environmental conditions, is the first requisite for ecosystem integrity. But it alone is not sufficient. An ecosystem must also be able to cope with changes in environmental conditions, that is stress. Thus in order to have integrity, an ecosystem must be able to attain and maintain an optimum operating point when stressed. (This optimum operating point may be different from the unstressed optimum operating point). Finally, an ecosystem which has integrity, must be able to continue evolving and developing, that is continue the process of self-organization on an ongoing basis. It is these latter two facets of ecosystem integrity that differentiate it from the notion of ecosystem health.

TABLE 1: The possible responses of an ecosystem to environmental change.(after Table 1, Kay, 1991a)

a) The ecosystem does not move from its original optimum operating point.

b) The ecosystem moves from its original optimum operating point but returns to it.

Issues concerning integrity to be considered for this case:

• How far is the system moved from its optimum operating point before returning?
• How long will it take to return to its optimum operating point?
• What is the stability of the system upon its return?

• Case 0: The ecosystem collapses.
• Case 1: The ecosystem remains on the original developmental pathway.
• Case 2: The ecosystem bifurcates from the original developmental pathway to a new one.
• Case 3: The ecosystem moves catastrophically to a different developmental pathway.

  Issues concerning integrity to be considered for each of these four cases:

1. How far is the new optimum operating point from the old?
2. How long does it take to reach the new optimum operating point?
3. What is the stability of the system about the new optimum operating point?
4. If the environmental conditions return to their original state, will the system return to the original optimum operating point?

Our understanding of the behaviour of complex self-organizing systems provides a framework for the investigation of environmentally induced changes in ecosystem organization and integrity. (Kay, 1991a) Table 1 summarizes the potential changes that can occur in an ecosystem's organization, if environmental conditions change. (The environmental change may be short term with the environment returning to its previous condition, or the change may persist.) This analysis establishes that ecosystems can respond to changes in the environment in qualitatively different ways. One response is for the system to continue to operate as before, even though its operations may be initially and temporarily unsettled. A second response is for the system to operate at a different level using the same structures it originally had (for example, a reduction or increase in species numbers). A third response is for some new structures to emerge in the system that replace or augment existing structures (for example, new species or paths in the food web). A fourth response is for a new ecosystem, made up of quite different structures, to emerge. This enumeration, of possible ecosystem responses to environmental change, is far richer than the simple classical notion that stress temporarily displaces an ecosystem from its climax, to which it hopefully returns. It also points out that an ecosystem has no single preferred state for which it should be managed.

This discussion identifies ways in which an ecosystem might re-organize in the face of environmental change, but not which re-organization constitutes a loss of integrity. It could be argued (and often is) that any environmental change, which permanently changes the optimum operating point, affects the integrity of the ecosystem. If this is correct, then an ecosystem would have integrity only if it has the ability to absorb environmental change without any permanent ecosystem change. Thus the other four distinct ecosystem responses to environmental change (Cases 0 through 3 in Table 1.) would constitute a loss of integrity, even though the latter three are responses in which the ecosystem reorganizes itself to mitigate the environmental change. This is not reasonable since the reorganized ecosystem is usually just as healthy as the original, even though it may be different. There is no prima facie scientific reason that an existing ecosystem should be considered to be the only one to have integrity in a situation, just because of its primacy.

It could also be argued that any system, that can maintain itself at any optimum operating point, has integrity. In this case, loss of integrity would occur only if the system is unable to maintain itself at an optimum operating point. (Case 0 in Table 1) Fortunately this is rarely the case, desertification being one of the few examples.

Neither of these definitions of integrity is operationally useful. The former definition is too restrictive in most situations, and reflects a desire to preserve the world exactly as it is. This denies the fundamental dynamic nature of ecosystems. It leads to disastrous mismanagement, e.g. the complete suppression of forest fires which eventually results in catastrophic conflagrations. (Of course one may wish to preserve an ecosystem as an example or specimen of a specific type.) The latter definition does not help managers as it restricts loss of integrity to a situation which rarely occurs and which is clearly undesirable. Hence this definition would be trivial.

A definition, that is between these two extreme, is to specify that some changes in optimum operating points are undesirable, and therefore represent a loss of integrity. But this would require a value judgement about which changes are desirable and which are undesirable. The science of ecology can, in principle, inform us about the kind of ecosystem response or reorganization to expect in a given situation. But it does not provide us with a scientific basis for deciding that one change is better than another, except possibly in the two extreme cases just discussed. So again the insight into ecological integrity, gained from complex systems theory, is that the physical and biological sciences can describe, and even predict, changes in the biosphere, but they alone cannot determine which is better. Ultimately an evaluation of the ecological acceptability of a human activity will depend on a value judgement about whether the resulting changes in the effected ecosystem are acceptable to the human participants.

In the final analysis, to define ecological integrity is to define a set of ecological characteristics to be monitored for change beyond specific values. To operationalize the notion of integrity requires the development of a monitoring framework and its associated measures and indicators. Much of this book is devoted to this question and only some of the highlights will be repeated here.

There are three distinct issues to be dealt with in developing a monitoring scheme for ecological integrity. First the changes in organization, to be associated with changes in ecological integrity, must be identified. This issue is naturally raised as part of the system's specification exercise discussed earlier. Then comes the scientific and technical problem of how to quantify these changes. What needs to be measured and how is it best done? These are scientific and technical issues we are all struggling with. Once measurements have been decided upon, the issue of evaluation becomes paramount. For what values of the measures will integrity be deemed to have been lost? Who will make this decision and who will act on it? The first and the last of these three issues require the understanding of physical and biological scientists to be combined with the concerns of society as voiced by elected officials, policy makers, public interest groups, and others. Only when this combination occurs, will it be reasonable to expect ecological integrity to result from our stewardship of the biosphere.

The process of developing a monitoring framework must start by identifying the users of the information gained from the monitoring. What information do they need, and in what form must it be presented to be usable? With this established, a system identification exercise is conducted so as to resolve such issues as what hierarchical levels will be focused on, what temporal and spatial scales will be covered, and what processes need to be monitored.

Measures for several different hierarchical levels and scales will be needed (Shackell & Freedman, King). The measures will be rooted in the bioregion and social issues in question (Keddy et al). Also, measures drawn from a number of different theoretical perspectives (e.g. landscape ecology, self-organization theory, population biology, etc.) will be required for a complete picture (Karr). Some measures will monitor the general condition of the ecosystem and its environment. Others will focus on specific known threats and the system's response to these threats. (Marshall et al, Woodley). Some will assess damage while others will serve as early warning alarms.

Clearly a variety of measures are necessary to adequately monitor ecological integrity. King points out that measures must not be over-integrated as this will result in the loss of valuable information. Steedman and Haider, and Keddy et al suggest methods for developing monitoring schemes and indicators. Woodley, Shackell and Freedman, Marshall et al., and Munn all discuss criteria for monitoring programs and indicators of ecological integrity. The work of Scheifer et al (1988) and Harris et al (1987) also provide guidelines for selecting measures. Recently the IJC has published a framework for developing indicators of ecosystem health for the Great Lakes Region (International Joint Commission, 1991).

Having completed the process of identifying the changes to be monitored and the measure thereof, we still face formidable technical and scientific problems. Ecology is still a young science and many methodological issues remain to be resolved. Karr points out, for example, that there is a tendency to take averages as the signal and variability in what is measured as noise. Both he and Woodley point out that the variability is often, in fact, the signal. But how to measure this?

The next step is development of evaluation criteria. Steedman and Haider propose a process for developing criteria in general, while other authors examine this issue in more specific contexts. A main problem in this respect is the lack of baseline data for comparison purposes. In this regard, Rubec and Marshall, in their summary of one discussion session, identify three priorities for Canada:

1. A first order of business must be integrating and synthesizing human activity and ecoregional information across Canada.
2. Development of national measures of ecosystem health and integrity will also require the creation of a national network of stable, secured and intercomparable benchmark reference sites with at least one such site in all ecoregions.
3. We must ensure that existing interdisciplinary monitoring sites and networks are maintained (such as the Experimental Lakes Area, and the Dorset, Turkey Lakes, Lac Laflamme and Kejimkujik Watersheds developed in the national acid rain program) to provide the long-term perspective essential to monitoring and uniquely available through these areas.

Complex systems theory and traditional science can help us describe and understand changes in ecological systems. Systems theory can help us focus on issues of importance, vis a vis integrity. However they alone cannot determine which ecological changes constitute a loss of integrity. When we define ecological integrity we are undertaking to integrate everything we know about an ecological system and where we want it to be. This integration, to be complete, must include the sum total of human preferences and concerns about the system. We must find paths for ecosystem development which assure our species survival both in the short and long term. Such paths will balance the needs of other species with our own, so as to maintain a biosphere in which humans have a sustainable niche.

Acknowledgements: Prof. Henry Regier and Prof. George Francis have discussed these ideas at length with me and included me in a number of workshops and meetings which they have held on the topic. Dr. Raf Serafin provided us with a written commentary on the workshop and discussions which I have drawn upon herein. Discussions with Prof. L. Westra helped focused my thinking on the non-scientific issues surrounding ecological integrity.

References:

Allen, T. F. H.; Hoekstra, T.W. "Toward a Unified Ecology",. New York: Columbia University Press; 1992.

Allen, T. F. H.; Starr, T. B. "Hierarchy: Perspectives for Ecological Complexity", University of Chicago Press; 1982.

Günther, F.; Folke, C. "Nested Living Systems". Stockholm: Royal Swedish Academy of Science; 1992. 22 pages. (Beijer Discussion Paper Series #5).

Harris, H. J. [and others]. "Coupling Ecosystem Science with Management: A Great Lakes Perspective from Green Bay", Lake Michigan, USA. Env. Mgmt.; 1987; 11(5): 619-625.

Holling, C.S., "The Resilience of Terrestrial Ecosystems: Local Surprise and Global Change. Clark, W.M."; Munn, R.E., Eds. Sustainable Development in the Biosphere: Oxford University; 1986: 292-320.

Holling, C.S., 1992, "Cross-scale Morphology, Geometry, and Dynamics of Ecosystems"; Ecological Monographs, in press

International Joint Commission, 1991, "A Proposed Framework for Developing Indicators of Ecosystem Health for the Great Lakes Region", 47 pages.

Kay, James. Self-Organization in Living Systems. Ph.D. thesis, Systems Design Engineering, University of Waterloo; Waterloo, Ontario, Canada, 1984.

Kay, J.J., 1991a. "A Non-equilibrium Thermodynamic Framework for Discussing Ecosystem Integrity", Environmental Management, Vol 15, No.4, pp.483-495.

Kay, J.J., 1991b. "The Concept of "Ecological Integrity", Alternative Theories of Ecology, and Implications for Decision-Support Indicators". in: Canadian Environmental Advisory Council Economic, Ecological, and Decision Theories: Indicators of Ecologically Sustainable Development. pp. 22-58 Commissioned background paper prepared for Canadian Environmental Advisory Council workshop on Indicators for Ecologically Sustainable Development, 25-26 July 1990, Ottawa, Canada.

Kay, J.J., Schneider, E.D., 1993. "Thermodynamics and Measures of Ecosystem Integrity" in Proceedings of the International Symposium on Ecological Indicators, Fort Lauderdale, Florida, Elsevier.(in press) 13 pages.

Schaeffer, David, J.; Herricks, E.; Kerster, H. "Ecosystem Health: I. Measuring Ecosystem Health", Env. Mgmt; 1988; 12(4): 445-455.

Schneider, E.D, Kay, J.J., 1993, "Life as a Manifestation of the Second Law of Thermodynamics" (in press), Advances in Mathematics and Computers in Medicine, 30 pages.

Serafin, R., Steedman, R., "Working Group Report: Measuring Integrity at the Municipal Level", from a workshop on Ecological Integrity and the Management of Ecosystems, Heritage Resource Center, University of Waterloo; Waterloo, Ontario, Canada 1991

Weinberg, Gerald M. "An Introduction to General Systems Thinking", John Wiley and Sons, 1975.

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