Ecosystem integrity

Sakson Soisontes and Mitra Ebrahimi
sakson.soisontes@gmail.com and mitra_ebrahimi@yahoo.com  

Abstract

Ecosystem integrity is a measure of the soundness, health and wholeness of an ecosystem. In nearly every part of the world, alarming numbers of ecosystems are under stress due to a variety of human impacts. The ecosystem integrity concept is an important response to the need to reduce human impacts on stressed ecosystems. It is a useful tool in environmental policy to help biodiversity maintenance, sustainability and resilience of ecosystems in a healthy natural balance, while at the same time allowing them to continue producing services that humanity depends on for survival.

1. Introduction

Ecosystem integrity is a concept that integrates the scientific study of ecosystems with the notions of integrity and environmental ethics. Because the concept of integrity involves human value judgments, defining ecosystem integrity is a challenge due to an apparent lack of scientific precision and the fact that integrity means different things to different people. Moreover, it is a complex, multi-faceted concept that is still evolving. The current rush to resolve challenges presented by various human impacts on ecosystems has caused many to take “easy-to-understand” views of the topic. Such an approach, however, tends toward oversimplification and distortion which can eventually lead to results that are far more harmful than helpful, both for the environment and for humanity. The concept of ecosystem integrity is vital to the preservation and restoration of ecosystems. Human beings depend on products and services produced by ecosystems, e.g. forestry products, seafood and soil for agriculture. Human life requires oxygen produced by plants and green algae in ecosystems. As a result of human exploitation, numerous ecosystems have been greatly altered, causing alarm about their future state. Therefore, governments and conservation groups have called for extensive management of ecosystems to preserve their existence for future generations. Ecosystem integrity has become one of the most essential tools for environmental system managers. Because of the pressing need to evaluate the integrity of ecosystems, governments have mandated the inclusion of ecosystem integrity into government land management policy and law which form the basis for managing public lands and a guide to the management of private ecosystems. Government agencies also need to establish clear goals and objectives for land management; ecosystem integrity is a vital supporting element in this effort. “The need for definitive guidelines and criteria is urgent” (Woodley, Kay and Francis 1993). Where ecosystems have been badly degraded through human intervention, the concept of ecosystem integrity provides a basis for assessing the needs and proposals required for ecological restoration (Bartson 1997).

2. Definitions

The concept of ecosystem integrity was first described in 1949 by Aldo Leopold, an American environmentalist, ecologist and forester. He wrote: "...a thing is right when it tends to preserve integrity, stability and beauty of the biotic community. It is wrong when it tends otherwise" (Leopold 1949). But Leopold only developed an ethical basis for integrity. He did not identify quantitative measures (Kay 2001). Following Leopold’s description, many attempts have been made to define ecosystem integrity but most have fallen short, often due to oversimplified views of the extremely complex nature of ecosystems. Several definitions, for instance, assume ecosystems become static in a simplistic idealized state of perfect balance and would continue in that state forever if left untouched by the effects of human existence. Ecosystems, however, are not static and defy simplified snapshot views that would disguise their dynamism and complexity over scales of time and space. Another common assumption is the notion that only human influence can downgrade ecosystems and cause loss of integrity. Ecosystems, however, can also undergo natural catastrophic interventions, such as floods, wildfires or earthquakes. Forest ecosystems, for example, are subject to many biotic and abiotic stresses, such as native insects and diseases, droughts and windstorms that can impact either whole forests or only specific species. Yet, ecosystems develop resiliency over time and do not necessarily become extinct, but change to meet natural conditions (Schlarbaum et al 1997). Finally, some descriptions of ecosystem integrity include a species-centered context. Focusing primarily on specific species, however, tends toward a narrow, fragmented view of ecosystems, which always include innumerable interrelated elements and functions both within themselves and with other ecosystems. For example, attempts to control the population of one species could lead to changes in other interrelated species, creating a structural imbalance within the system. Furthermore, “the resilience of the system to change is embedded in its heterogeneity and dynamic properties...” (De Leo and Levin 1997). Misguided efforts to improve an ecosystem can become detrimental, even reducing its diversity and resilience. Defining ecosystem integrity is a widely recognized challenge, as noted by Ulanowicz (2000): “The notion of ecosystem integrity has repeatedly appeared in the legislation of Canada and the United States in the absence of serious consideration as to exactly what the term means.” The Global Integrity Project identifies the concept of ecosystem integrity incorporating four attributes: “(1) system ‘health’, that is, continued successful functioning of the community; (2) capacity to withstand stress; (3) undiminished ‘optimum capacity’ for the greatest possible ongoing developmental options; and (4) continued ability for ongoing change and development, unconstrained by human interruptions.” The first attribute implies the system’s ability to sustain its function and structure. “The function, or vigor, of a system relates to its overall level of activity in processing material and energy. Its structure, or organization, refers to how effectively its various processes are linked to each other. Together vigor [function] and organization [structure] specify the system level of performance…”, that is, its integrity (Ulanowicz 2000). Barkmann et al (2001) discuss ecological integrity with the concepts of sustainable development, ecological services and self-organizing capacity of ecosystems. Sustainable development is an important concept in environmental management, which can be described as keeping available ecosystem services on a long term and broad scale. According to them, as all ecosystem services are dependent on regulating functions of ecosystems and their self-organizing capacities, the ability of ecosystems to preserve their self-organizing processes is a basic concept in sustainable development. Therefore, Barkmann et al. (2001) have defined ecological integrity as a “political target for the preservation against non-specific ecological risks that are general disturbances of the self-regulating capacity of ecological systems”; and supporting the processes which are essential for the ability of ecosystems for self-organization (Müller 2005). Another concrete definition includes three essential elements of ecosystems—renewable services, sustainability and resiliency—and their measurement. “Ecosystem integrity is a measure of the capacity of ecosystems to renew themselves and continually supply resources and essential services. Ecosystem integrity is the degree to which all ecosystem elements—species, habitats and natural processes—are intact and functioning in ways that ensure sustainability and long-term adaptation to changing environmental conditions and human uses” (Great Lakes Commission 2003).

3. Assessment of ecosystem integrity

Following are five commonly recognized criteria for assessing ecosystem integrity (Woodley, Kay and Francis 1993):

1. Is the ecosystem sustainable? Is it capable of renewing and perpetuating itself?
2. Is the ecosystem resilient? Does it resist invasion by foreign species from outside itself?
3. Does the ecosystem freely produce resources and services? Is its productivity unimpaired?
4. Does the ecosystem retain nutrients unimpaired?
5. Is the biota, plus all its interactions both within and outside itself, unimpaired?

Based on these five criteria, James Kay (2001) established six fundamental elements that should be incorporated in any assessment of ecosystem integrity:

1. Ecosystems are naturally dynamic in both time and space. Their boundaries are not fixed entities; nutrients, species and flows of energy are far more important than precise boundaries.
2. Processes within ecological systems operate on a wide variety of levels. Descriptions of ecological integrity must evaluate ecosystems to a broad enough extent to capture entire processes, as well as on a wide variety of scales in time and space, both large and small.
3. Assessments of ecological integrity must constantly recognize that ecosystems are extremely complex systems. They do not exhibit mere single points of stable equilibrium, but rather have multitudes of steady states across time and space. As ecosystems develop, for example, they become more efficient in dissipating solar energy, while, conversely, environmental fluctuations tend to disorganize the system’s dissipating capacity. Too little or too much of any of these opposing forces creates imbalance, upsetting system efficiency and effectiveness. When disorganizing forces of the environment balance against organizing forces of the ecosystem, optimum operation is established. So, our concept of integrity must recognize the ability of ecosystems to reach and maintain their optimum operation.
4. Ecosystems exhibiting symptoms of stress have their integrity threatened. Symptoms of stress, e.g. increased respiration and decreased productivity, might indicate the system is retreating from its optimum operating point. The system’s ability to respond to the stress and move back toward its optimum operation is essential in any discussion of stress and loss of integrity. So, the concept of resilience is critical in defining and assessing ecosystem integrity.
5. Human interrelationships with ecosystems are often viewed as separate from the natural elements of ecosystems, but humans are inextricably tied to and dependent on ecosystems for survival. The activities of humans continually produce stresses on ecosystems, and these stresses must be monitored and quantified.
6. The concept of ecosystem integrity is based on human values and therefore will be viewed differently by different individuals. So, a definition of integrity must specifically identify the human value judgments that influence its particular perspective.

These points are summed up in axioms of ecosystem health (Costanza et al 1993), which Müller (2004) uses to identify the basic fundamentals of ecosystem integrity (Table 1).

Table 1. Axioms of ecosystem health and integrity (Müller 2004)

Dynamism	Nature is a set of processes, more than a composition of structures
Relatedness	Nature is a network of interactions
Hierarchy	Nature is built up by complex hierarchies of spatio-temporal scales
Creativity	Nature consists of self-organizing systems
Different fragilities	Nature includes various sets of different resiliencies

 
4. Indicators of ecosystem integrity

According to Munn (1993), two types of ecological indicators needing constant monitoring and quantifying are Threat Indicators and Reduced Threat Indicators, which can be used to alert the scientific community, governmental, political and conservation groups, and the general public to potential reductions or improvements in ecosystem integrity. Some fundamental global indicators of “threats” to integrity are:

1. Increasing population, particularly as urbanization
2. Increasing energy consumption, both in terms of per capita and total amounts, e.g. the amount of energy consumed to produce one unit of manufactured goods
3. Increasing water consumption, both per capita and total amounts
4. Increasing depletion of both renewable and nonrenewable resources, e.g. forests, high-grade agricultural land and mineral reserves (including petroleum)
5. Increasing volumes of waste materials
6. Transportation indicators, such as increasing numbers of automobiles and trucks, increasing kilometers of roads built, and increasing numbers of airline passengers

Some global indicators of “reduced threats” to ecosystem integrity, or improved system health, are:

1. Increasing production output for every unit of natural resources consumed, including both renewable and nonrenewable resources
2. Increasing efforts to recycle items that otherwise would have been waste material
3. Increasing conservation of scarce or highly valued resources, e.g. endangered species, wilderness areas and natural monuments
4. Declining sales and usage of both pesticides and herbicides
5. Increasing citizen involvement in actions that benefit the environment

The last indicator is essential. The more that all parties linked to an ecosystem can partner together in joint efforts to maintain or improve ecosystem integrity and management, the greater the level of achievement. Without broad-based cooperation of all parties, including government, conservationists, local communities and ecology managers, conservation efforts are hampered. Based on the orientor principle, Müller (2005) has proposed a set of indicators for ecological integrity (Table 2). Throughout undisturbed development of ecosystems certain characteristics of ecosystems increase steadily and develop toward a certain attractor state. These characteristics (orientors) are used as indicators of naturalness of an ecosystem. Based on the criteria and requirements of ecological indicators, a small set of important orientors is selected as indicators. This small set of indicators represents a holistic, interdisciplinary approach of quantifying the complexity of ecosystem organization to determine ecosystem integrity. The indicator set is used to represent the state of a terrestrial ecosystem’s organization and consists of the most important variables in an ecosystem that can be measured in numerous local instances. Müller includes within ecosystem organization the general subsystems of ecosystem structures and ecosystem functions. Ecosystem structures to be quantified include both biotic and abiotic features. As an ecosystem evolves, the biotic structures, or quantities of integrated species, steadily increase and create greater biodiversity. Simultaneously, the abiotic features become increasingly complex and heterogeneous. As the number of structural elements increases, ecosystem functions become more complex. Ecosystem functions to be quantified include energy balance (indicated by increased exergy capture, or uptake of usable energy, and entropy production); water balance (indicated by increased uptake of water, particularly of plants, which is regulated by the degree of plant transpiration); and matter balance (indicated by increased nutrient storages and reduced loss of nutrients).

Table 2. Indicator set to represent the organizational state of ecosystems (Müller 2005)

Orientor group	Indicator	Potential key variable(s)
Biotic structure	Biodiversity	Number of species
Abiotic structures	Biotope heterogeneity	Index of heterogeneity
Energy balance	Exergy capture entropy production entropy production after Svirezhev and Steinborn output by evapotranspiration and respiration Metabolic efficiency	Gross or net primary production entropy production after Aoki.   Respiration per biomass
Water balance	Biotic water flows	Transpiration per evapotranspiration
Matter balance	Nutrient loss storage capacity	Nitrate leaching intrabiotic nitrogen soil organic carbon

It should be mentioned that the indicator set in Table 2 is not a complete one to indicate sustainability, as it does not include economic and social aspects. In summary, indicators and monitoring are important tools for measuring ecosystem integrity as a means of quantifying specific ecosystem elements of integrity that otherwise would exist only in theory.

 
5. Methods for quantifying and monitoring ecosystem integrity

To assess the integrity of an ecological system, some fundamental elements must be monitored and quantified at specific ecosystem sites. “The purpose of monitoring is to detect changes in ecological integrity, using appropriate indicators. The consequences of monitored changes are evaluated on the basis of a cumulative knowledge of ecological principles gained from research. For example, changes in the rate at which natural forest is being clearcut and converted to silvicultural plantations can be monitored. The consequences, for ecological integrity, are evaluated using an understanding, however incomplete, of effects on biomass, productivity, soil and streamwater chemistry, watershed hydrology, biodiversity and global change” (Shackell, Freedman and Staicer 1993). Even though these effects may not be completely understood, since so much remains to be learned through research about how ecosystems actually work, at least enough is currently understood to make some viable choices in ecosystem management. Shackell, Freedman and Staicer (1993) have proposed two types of monitoring sites for assessing ecological integrity: intensive and extensive monitoring sites: Intensive monitoring: At a few selected intensive monitoring sites in each ecozone, intensive multidisciplinary studies can be conducted, which are designed to perform four functions:

1. “Detect changes in sites relatively undisturbed by humans, for use as a baseline reference
2. “Refine currently used indicators, and develop new or better indicators
3. “Detect changes in structural and/or functional attributes of monitored ecosystems
4. “Develop predictive models of ecosystem dynamics, that would allow distinguishing between natural and anthropogenic causes of change”

Extensive monitoring: Extensive monitoring sites are designed to perform basically two functions:

1. “Monitor the effects of extensive human activities, e.g. agriculture, forestry, mining, as compared to a reference (intensive) site or to a known historical condition”
2. Monitor changes in the region’s ecological character due to changes in land use patterns

In another approach, Ulanowicz (2000) discusses that an ecosystem’s level of performance determines the ecosystem’s integrity—its strength of function, organization and resilience. He mentions that specific levels of ecosystem performance can be measured by quantifying networks of trophic exchanges of material or energy that take place within a system. Measuring these exchanges gives the performance level, or integrity, of a system. Four types of exchanges, or energy flows, can be found occurring within an ecosystem: (1) the rate at which a taxon contributes as prey to a predator’s sustenance which follows certain pathways depending on organism morphologies and behaviors (an intrasystem exchange, which make up the large majority of transfers in ecosystems), (2) external inputs to the system, e.g. solar radiation (an exogenous exchange), (3) exports of medium useful to other systems, e.g. oxygen (exogenous exchange), and (4) exports of medium unusable by other systems, e.g. waste products (exogenous exchange). Sets of measurements of these four flows of all the important taxa in an ecosystem allow degrees of function, organization and resilience occurring in the system to be quantified. Function, or vigor, for instance, can be quantified as the sum of all the energy exchanges in the system (Ulanowicz 2000). “If one has access to sufficient data to assemble a network of trophic interactions, one is equipped to assess the ecosystem integrity in a quantitative way” (Ulanowicz 2000). Thus, ecosystem integrity, sometimes viewed by skeptics as a vague human-value variable impossible to measure with any precision, can in fact be specifically measured and quantified using scientific methods.

6. Case study

Here a study on assessing ecosystem integrity is discussed from the research project “Bornhoeved Lakes”. A 100-year-old beach forest and neighboring arable land were investigated between 1988 and 2001 in the research area of Altekoppel in northern Germany. Using Müller’s set of indicators for assessing ecosystem integrity; these two areas were compared for their ability and capacity for self-organization. The complete description of methodologies for obtaining the indicators is published in Schimming and von Stamm (1993), and measurements are described in Hörmann et al. (1992). As shown in Figure 1, the values for the forest are higher for all the indicators of self-organization except for exergy capture. High exergy capture in arable land means the farmer has achieved an optimal production in this area. Overall, the self-organization and corresponding ecological integrity were much higher for the forest than for the arable land.

Figure 1. Comparing the ecological integrity for forest and arable land ecosystems, after Müller (2005)

7. References

1. Barkmann, J., Baumann, R., Meyer, U., Müller, F., and Windhorst, W. (2001) Ökologische Integrität: Risikovorsorge im Nachhaltigen Landschaftsmanagement. Gaia 10, 97–108.
2. Bartson, A. P. (1997). What Is Ecosystem Integrity? In Smith River Fisheries and Ecosystem Report. Retrieved 23 April 2009, from http://www.geocities.com/RainForest/3771/102what.html  
3. Costanza, R. (1993). Towards an operational definition of ecosystem health, in Costanza, R., Norton, B.G., and Haskell, B.D., Ecosystem Health, (pp. 239–256), Eds. Washington. Online google books.
4. De Leo, G. A. and Levin, S. (1997). The Multifaceted Aspects of Ecosystem Integrity. Ecology and Society: A Journal of Integrative Science for Resilience and Sustainability, 1(1). Retrieved 20 April 2009 from http://www.ecologyandsociety.org/vol1/iss1/art3/
5. Great Lakes Commission. 29 Apr. 2003. Glossary of Technical Terms That Appear in the LaMPs. Human Health and the Great Lakes. Retrieved 20 April 2009, from http://www.great-lakes.net/humanhealth/about/words_e.html  
6. Hörmann, G., Irmler, U., Müller, F., Piotrowski, J., Pöpperl, R., Reiche, E.W., Schernewski, G., Schimming, C.G., Schrautzer, J., and Windhorst, W. (1992) Ökosystemforschung im Bereich der Bornhöveder Seenkette. Arbeitsbericht 1988–1991. Ecosystem I, pp. 1-338.
7. Kay, J. (2001). The Ecosystem Approach to Monitoring Integrity. Retrieved 25 April 2009, from http://www.nesh.ca/jameskay/www.fes.uwaterloo.ca/u/jjkay/HNA/g_Integrity.html  
8. Leopold, A. (1949). A Sand County Almanac. New York: Oxford University Press. Müller, F. (2004). Ecosystem Indicators for the Integrated Management of Landscape Health and Integrity. In S. E. Joergensen, R. Costanza and X. Fu-Liu (Eds), Ecological Indicators for Assessment of Ecosystem Health (pp. 277-303). Boca Raton: Taylor and Francis.
9. Müller, F. (2005). Indicating Ecosystem and Landscape Organization. Ecological Indicators, 5, 280-294.
10. Munn, R. E. (1993). Monitoring for Ecosystem Integrity. In S. Woodley, J. Kay, & G. Francis (Eds.), Ecological Integrity and the Management of Ecosystems (pp. 105-115). Ottawa: Heritage Resources Centre, University of Waterloo, and Canadian Parks Service.
11. Schimming, C.G. and von Stamm, S., (1993). Arbeitsbericht des Projektzentrums Ökosystemforschung, Anhang I: Untersuchungsmethoden. Interne Mitteilungen aus dem FE-Vorhaben Ökosystemforschung im Bereich der Bornhöveder Seenkette.
12. Schlarbaum, S. E., Hebard, F., Spaine, P. C. and Kamalay, J. C. (1997). Three American Tragedies: Chestnut Blight, Butternut Canker, and Dutch Elm Disease. In Britton, K.O., 1997, Proceedings, Exotic Pests of Eastern Forests (pp. 45-54). Nashville, TN. Tennessee Exotic Pest Plant Council, Retrieved 21 April 2009, from http://www.srs.fs.usda.gov/pubs/ja/ja_schlarbaum002.htm  
13. Shackell, N. L., Freedman, B. and Staicer, C. (1993). National Environmental Monitoring: A Case Study of the Atlantic Maritime Region. In S. Woodley, J. Kay and G. Francis (Eds.), Ecological Integrity and the Management of Ecosystems (pp. 131-153). Ottawa: Heritage Resources Centre, University of Waterloo, and Canadian Parks Service.
14. Ulanowicz, R. E. (2000). Toward the Measurement of Ecological Integrity. In D. Pimentel, L. Westra, & R. F. Noss (Eds.), Ecological Integrity: Integrating Environment, Conservation, and Health (pp. 99-113). Washington, DC: Island Press.
15. Woodley, S., Kay, J. J. and Francis, G. (Eds.). (1993). Ecological Integrity and the Management of Ecosystems. Ottawa: Heritage Resources Centre, University of Waterloo, and Canadian Parks Service.

8. Helpful Links

• Global Ecological Integrity Group http://www.globalecointegrity.net/  
• James J. Kay, 1954-2004 http://www.nesh.ca/jameskay/www.jameskay.ca/
• Parks Canada http://www.pc.gc.ca/  
• U.S. Environmental Protection Agency, National Center for Environmental Economics http://yosemite.epa.gov/ee/epa/eed.nsf/webpages/homepage  
• U.S. Environmental Protection Agency, National Center for Environmental Research http://epa.gov/ncer/