openLandscapes - Ecosystem Health

ECOSYSTEM HEALTH

University of Kiel, Ecology Centre, MSc Environmental Science, a seminar paper
Status: completed

Svetlana Khamnueva and Valentine Denis Pankaj
khamnueva@gmail.com and valentinepankaj@gmail.com

Abstract

An ecosystem is called healthy if it is stable and able to provide the goods and services, and at the same time if it is able to maintain its structure, function over time and under stress conditions. Over the past half century it has become apparent that many agricultural and industrial activities have cumulatively damaged ecosystems and landscapes, thus significantly compromised the health of ecosystems, upon which human beings are strongly dependent. The integrative concept and framework of ecosystem health provides an effective approach to manage our ecosystem and ourselves, in order to ensure a healthy and sustainable future.

Content

1. Introduction

Nowadays the mankind has become an inseparable component of the ecosystem Earth, whereas the activity of humans is influencing significantly the structure and function of this ecosystem. Unfortunately, the impacts of such activities on ecosystems are, as a rule, negative. These interferences lead to drastic changes in ecosystem state on different spatial and temporal scales. In order to understand and to be able to mitigate and avoid such unfavourable alterations in ecosystem condition, integration of the ecological and economical approaches took place. Therefore, the concept of Ecosystem Health has been formed. Aldo Leopold first formulated the basic ideas of the Ecosystem Health concept in 1914. As the concept includes ecological, economic and social aspects, there were and still are many uncertainties, especially comparing Ecosystem Health with the concept of Ecosystem Integrity. Therefore, at present it is very important to give a clear definition of Ecosystem Health, establish the methods of its assessment and ways of implementation of the results of Ecosystem Health Assessment in environmental management.

back

2. Defining the concept of ecosystem health

The need to define the concept of ecosystem health in practical terms arises because of the failure of current economic paradigms to protect the natural environment, which is, after all, the foundation for economic systems. The ecosystems health paradigm proposed in "Ecosystem Health: New Goals for Environmental Management" (1992) uses a broad medical model, even while recognizing that the parallel between medicine and environmental protection does not always hold (Norton et al. 1991). Therefore, most easily it can be defined as the absence of disease, but it does not reflect the main aim of introducing this concept and is the object of criticism by a number of scientists (Wayne G. Landis and John F. McLaughlin). The greatest criticism of the term is that it has very limited practical application to management. Because health is a metaphorical model, it cannot be measured directly (Rapport et al. 2002). Moreover, the concept of Ecosystem Health has been thought to be inappropriate for ecosystems as ecologists claimed that ecosystems were not organized as organisms. They were partly right; indeed, ecosystems are not organized in the same manner as organisms. Ecosystems are not superorganisms. Ecosystems do, however, have organization, structure, and function. They constitute another level above that of populations – but below that of landscapes and biomes – in the biological hierarchy from cells to the biosphere. Thus, ecologists were wrong to assume that, because ecosystems are not organized in the same manner as organisms, the concept of health had no application to this level (Rapport et al. 2002).

There are different purposes of defining Ecosystem Health and there are different approaches to this issue.

For instance, project officials see ecosystem health as a "condition where the parts and functions of an ecosystem are sustained over time and where the system’s capacity for self-repair is maintained, such that goals for uses, values, and services (Ecosystem Services) of the ecosystem are met" (Rapport et al. 2002).

J. D. Karr (1993) defines ecosystem health as "the condition in which a system realizes its inherent potential, maintains a stable condition, preserves its capacity for self-repair when perturbed, and needs minimal external support for management."

In general, it was concluded that ecosystem health is closely linked to the idea of sustainability and can be defined as "a concept that integrates environmental conditions with the impacts of anthropogenic activities in order to give information for a sustainable use and management of natural resources" (Burkhard et al. 2008).

R. Costanza in his work "Towards an operational definition of ecosystem health" (1992) tries to answer a crucial question in this respect: how can we create a practical definition of ecosystem health that is applicable with equal facility to complex systems at all scales? In order to answer this question he lays out the minimum characteristics of such definition. First, an adequate definition of ecosystem health should be a combined measure of system resilience (Ecosystem Resilience), balance, organization (diversity), and vigor (metabolism). Second, the definition should be a comprehensive description of the system. Looking at only one part of the system implicitly gives the remaining parts zero weight. Third, the definition will require the use of weighting factors to compare and aggregate different components in the system. And fourth, the definition should be hierarchical to account for the interdependence of various time and space scales. Thus, B. D. Haskell et al. (1992) offered the following working definition: "An ecological system is healthy and free from "distress syndrome" if it is stable and sustainable – that is, if it is active and maintains its organization and autonomy over time and is resilient to stress" (Rapport et al. 2002). Ecosystem health is thus closely linked to the idea of sustainability, which is seen to be comprehensive, multiscale, dynamic measure of system resilience, organization, and vigor. This definition is applicable to all complex systems from cells to ecosystems and economic systems (hence it is comprehensive and multiscale) and allows for the fact that systems may be growing and developing as a result of both natural and cultural influences. Distress syndrome refers to the irreversible processes of system breakdown leading to death (Rapport et al. 1981).

With reference to aquatic ecosystems, the ecosystem distress syndrome comprises the following symptoms: alteration in biotic community structure to favour smaller forms; reduced species diversity; increased dominance by ’r’ selected species; increased dominance by exotic species; shortened food-chain length; increased disease prevalence; and reduced population stability (Rapport 1991). While stressed ecosystems do not manifest all the above symptoms, in the vast majority of cases, most of these symptoms do appear (Rapport et al. 1985).

Therefore, R. Costanza (1992) summarizes the concept definition of ecosystem health as:

Homeostasis.
Absence of disease.
Diversity or complexity.
Stability or resilience.
Vigor or scope for growth.
Balance between system components.

He emphasizes that it is necessary to consider all or at least most of the elements simultaneously. Consequently, he proposes an overall system health index:

HI = V * O * R

Where HI is system health index, also a measure of sustainability; V is system vigor, a cardinal measure of system activity, metabolism, or primary productivity; O is the system organization index, a 0-1 index of the relative degree of system’s organization, including its diversity and connectivity; R is the system resilience index, a 0-1 index of the relative degree of the system’s resilience.

To make it clear, it should be mentioned that the concepts of Ecosystem Health and Integrity, although related, are fundamentally different. Karr and Chu (1999) defined ecosystem health as a preferred state of ecosystems modified by human activity (e.g., farm land, urban environments, airports, managed forests). In contrast, ecological integrity is defined as an unimpaired condition in which ecosystems show little or no influence from human actions. Ecosystems with a high degree of integrity are natural, pristine, and often labelled as the base line or benchmark condition.

Also, the specific features of ecosystems structure and function should always be taken into account. These important issues were organized by B. G. Norton (1991) into axioms of Ecosystem Health:

The axiom of dynamism: nature is a set of processes and more than a collection of objects.
The axiom of relatedness: all processes are related to other processes.
The axiom of hierarchy: processes are not related equally but are unfold in systems within the system. The respective processes differ in the temporal and spatial scales at which they are organized.
The axiom of creativity: the autonomous processes of nature are creative and represent the basis of all biologically based productivity.
The axiom of differential fragility: the ecological systems, which form the context of all human activities, vary in the extent to which they can absorb and equilibrate human caused disruptions in their autonomous process.

back

3. Indicating ecosystem health

Since the concept of ecosystem health emerged, environmental managers and ecologists have asked the question: How to check whether an ecosystem is healthy or unhealthy? Which ecological indicators should we apply? It is clear today that it is impossible to find one indicator or even few indicators that can be used generally. According to the definition of Burkhard et al. (2008), "ecosystem health is a concept that integrates environmental conditions with the impacts of anthropogenic activities in order to give information for a sustainable use and management of natural resources". Therefore, related indicators have to reflect these anthropogenic impacts to represent the complex cause and effect relations in human–environmental systems. For instance, in comparison to the assessment of human health, it is also difficult to assess health of a human, but it is possible to set up a range of parameters which are common for healthy people that allows identifying condition of humans. As a physician uses general indices as temperature, blood pressure to assess human health, such general attributes like land cover, species abundance, or water body conditions can be found in ecosystems also. However, while physicians focus on the health of a single patient, environmental managers have to concentrate on the multiple social, economic, and natural levels and scales of the ecosystem (Haskell et al. 1992).

However, there are some complications, which should be taken into consideration before derivation of the indicators. First, each ecosystem has its own set of indicators and endpoints; therefore each ecosystem must be assessed separately. Second, the process of succession presents a problem: if conditions change, a new ecosystem that is better adapted to the new conditions will replace the prior system. Consequently, the indicators and variables must be sufficiently dynamic to change accordingly. Third, each scientist evaluating the ecosystem will choose different variables depending on his or her specific interest and expertise (Costanza et al. 1992).

There are three basic principles (pillars) of indicator derivation (Joergensen et al. 2005). The first guideline which guarantees a high applicability and a general correctness, origins in fundamental ideas from ecosystem theory: ecosystems are comprehended as self-organizing entities, and the degree of self-organizing processes and their effects have been chosen as an aggregated measure to represent the systems’ actual states. The second pillar is built-up by the methodologies of ecosystem analysis: to depict ecological entities in a holistic manner, structure as well as function has to be taken into account, the latter representing the performance of the ecosystems. Finally, for utilization in environmental management, the basic approaches which emerge from these principles have to be reflected on a normative level. As the factual evaluation of the concrete indicator values is the societal (not an ecological) task, a useful indicator set has to be based on political concepts and targets. Indicators therefore, in accordance with F. Mueller et al. (2000), should comprise a high political relevance, they should be correct from an analytical point of view, they should do justice to statistical demands, such as quantifiability, reproducibility, validity, sensitivity, or transparency and they should have a high qualitative ecological foundation as well as a system-based, well-elaborated environmental consistency. Consequently, environmental indicators should not only be derived considering pragmatic arguments, but also referring to an optimal ecosystem theoretical background.

There are different concepts of indicator derivation, for example, in the Handbook of Ecological Indicators for Assessment of Ecosystem Health (2005) the following classification of ecosystem health indicators is suggested.

Level 1.	Presence or absence of specific species. Bellan’s Pollution Index. Pollution Index Based on Ampiphoids. AZTI Marine Biotic Index. Bentix. Macrofauna monitoring index. Benthic response index. Conservation Index.
Level 2.	Ecological strategies Index of r/K strategists. Nematodes/Copepodes Index. Polychaetas/Amphipods Index. Infaunal Index. Feldman index.
Level 3.	Ratio between classes of organisms. Nygard’s algal index. Diatoms/nondiatoms ratio.
Level 4.	Concentrations of chemical compounds (e.g. total phosphorus concentration).
Level 5.	Concentrations of entire trophic levels (e.g. concentration of phytoplankton as indicator for the eutrophication of lakes).
Level 6.	Process rates (primary production determinations as indicators for eutrophication; a high annual growth of trees in a forest as an indicator for a healthy forest ecosystem; high mortality in a population as an indicator of unhealthy environment).
Level 7.	Composite indicators (biomass, respiration/biomass, respiration/production, production/biomass, primary producers/consumers).
Level 8.	Holistic indicators. Vigor, organization, and resilience (V-O-R model). Buffer capacity. Diversity indexes (Shannon–Wiener index, Pielou Evenness Index, Margalef Index, Berger-Parker Index etc.). Size and connectivity of the ecological network. Turnover rate of carbon/nitrogen .
Level 9.	Thermodynamic variables (exergy, energy, exergy destruction, entropy production, power, mass and energy system retention time).

Not all of the listed indicators are to be used in every assessment of ecosystem health. One of the convenient and operational procedures of selection of the most significant and important indicators is application of DPSIR framework for indicator derivation (DPSIR approach). Another method widely used in such researches is the Orientor approach, where it is assumed that certain characteristics of an ecosystem are developing towards an attractor state which is restricted by the specific site conditions and the prevailing ecological functions (Joergensen and Mueller 2000, Orientor approach). The result of Ecosystem Health Assessment (EHA) is supposed to provide a basis (whether an ecosystem is healthy or unhealthy) for management decision. However, such outcomes are not always facilitating decision-making, but cause even more confusion. Quite often the results of EHA are presented in the form of obtained values of indicators, which have to be interpreted in terms of management actions. The name of this technique is Direct Measurement Method (DMM) and the procedures established for this method are as follows (Joergensen et al. 2005):

Identify the necessary indicators to be applied in the assessment process.
Measure directly or calculate indirectly the selected indicators.
Assess ecosystem health based on the resulting indicator values.

Management decisions can be facilitated by means of another tool - Ecosystem Health Index Method (EHIM), which allows quantitative assessment of the state of ecosystem health. EHI can be calculated by the equation (Joergensen et al. 2005):

Where EHI is a synthetic ecosystem health index, EHIi is the i ^th ecosystem health index for the i ^th indicator, ωi is the weighing factor for the i ^th indicator.

The procedure established for ecosystem health assessment using EHI method is shown in figure 1.

Figure 1. The procedure of EHI method for ecosystem health assessment (Source: Joergensen et al. 2005)

The process of EHA using EHI method consists of five steps (Joergensen et al. 2005):

Select basic and additional indicators.
Calculate sub-EHIs for all selected indicators.
Determine weighing factors for all selected indicators.
Calculate synthetic EHI using sub-EHIs and weighing factors for all selected indicators.
Assess ecosystem health based on synthetic EHI values: 0-20% worst; 20-40% bad; 40-60% middle; 60-80% good; 80-100% best.

However, one should be careful when using such method as, despite the use of weighing factors, taking such "average" has many drawbacks. The most significant disadvantage of the EHI method is loss of important information and specific data on different levels of ecosystem organization.

Also, it should be mentioned that the application of indicators on appropriate temporal and spatial scales can be restricted by limited data availability. For this reason, surrogates or suboptimal parameters have to be used quite often for the quantification of indicators.

back

4. Environmental management and ecosystem health

The idea to apply ecosystem health assessment (EHA) to environmental management has emerged in the late 1980s. Nowadays the basic goals of environmental management shifted from single-species management and protection of the environment from pollution to the ideas of sustainability, which are closely related to the Ecosystem Health concept. It has been realized that "monitoring for ecosystem health is far broader in scope than simply monitoring bio-physical attributes. A watchful eye is also required to identify the socioeconomic, cultural and human health manifestations of dysfunctional ecosystems" (Maffi 2001).

The idea behind the assessment of ecosystem health is that if we observe that an ecosystem is not healthy, we want to find out what is wrong. What caused this unhealthy condition? What can we do to bring the ecosystem back to normal? To answer these questions and come up with a cure, ecological indicators are applied (fig. 2). Further more appropriate assessments have to bridge between natural, social, economic, and health science to integrate human norms and values with the aim to support sustainable management of natural resources.

Figure 1. How ecological indicators are used for EHA and how to follow the effect of the environmental management plan (Source: Joergensen et al. 2005)

With regard to environmental management, decision makers’ actions are required if the ecosystem health indicators reach undesirable levels in order to restore preferred conditions and the functions of the respective ecosystem (Burkhard et al. 2008). Therefore, the results of Ecosystem Health Assessment have to become the first priority in decision making. This, unfortunately, still does not happen in most cases, even though these days many scientists, politicians, environmentalists, and others see ecosystem management as the path to a correct relationship between people and nature. They argue for the new paradigm of ecosystem management because, according to C. Reidel and J. Richardson (1995), "the old paradigms are no longer scientifically or politically valid". The traditional anthropocentric approach to natural resource policy that blends multiple use, conservation, preservation, and protection of human health leads to "collapse of life and living as we know it" and must be replaced by "ecocentrism… and ecosystem management" according to R. Nash (1994). In the new paradigm world of ecosystem management, protection of ecosystem health, integrity, and sustainability replaces concern for improvement in human well-being at the core of government environmental and natural resource policies. Therefore, ecosystem approach in the processes of ecosystem management, aimed to preserve or restore ecosystem health, has to be the major strategy for the integrated management of land, water and living resources that promotes conservation and sustainable use in equitable way.

back

5. Summary

Therefore, ecosystem health, while still debated in terms of its fundamental meanings, has entered the world of policy and practice (Lackey 2001). Surprisingly, the new concept first found support from the medical and public health fields rather than from ecology. This fact can be explained not only by use of medical terminology "health", but also by the gradual recognition of the role of healthy ecosystems in human health and well-being in general (mainly due to provision of goods and services). Moreover, since the Stockholm Conference on the Environment (1972) and the United Nations Conference on Environment and Development (Rio Declaration, 1992), it has also been realized that economic development is also dependent on maintaining healthy ecosystems. Even now, when the process of realizing and recognizing that healthy ecosystems perform services upon which humans and other biota are dependent, is at its initial stage the concept of ecosystem health is applied in practice. It helped to understand the problems, their reasons and restore the world’s most damaged environments (from Colorado River delta to Langat Basin of Malaysia). Thus, actions that threaten ecosystem health and threaten continued supply of ecosystem services are coming under more intense scrutiny. The public and decision makers are becoming aware that, unless the health of the world’s ecosystems is restored and maintained, socioeconomic aspirations will become increasingly compromised.

If ecosystem health is to be maintained – and restored where it has been lost – what is needed above all else is the recognition that the politics of the environment inevitably must change. Government must use regulations, permitting, planning, and other means to control land use on public and private lands to ensure that ecosystems remain healthy or restored to a state of health.

back

References

Burkhard B., Mueller F., and Lill A. 2008. Ecosystem Health Indicators. University of Kiel, Kiel Germany. Ref. Ecological Indicators. Vol. 2 of Encyclopedia of Ecology, 5 Vols. pp. (1132-1138).
Costanza R. 1992. Toward an operational definition of ecosystem health. Pages 239-256 in Costanza R., Norton B. G., and Haskell B. D., editors. Ecosystem health: new goals for environmental management. Island Press, Washington, D. C., USA.
Costanza R., Norton B.G., and Haskell B.D. 1992. Ecosystem Health: New. Goals for Environmental Management. Washington, D C: Island. Press. Retrieved from: http://books.google.co.uk/
Haskell B. D., Norton B. G., and Costanza R. 1992. Introduction: What is ecosystem health and why should we worry about it? In Costanza R., Norton B.G., and Haskell B.D. Ecosystem Health: New. Goals for Environmental Management. Washington, D C: Island. Press, 1992, pp. 3-20.
Joergensen S. E., Costanza R., and Fu-Liu-Xu. 2005, Handbook of Ecological Indicators for the Assessment of Ecosystem Health. Boca Raton, Florida (USA). CRC Press.
Joergensen S. E., Mueller F. 2000. Ecological orientors – a path to environmental applications of ecosystem theories. In: Handbook of Ecosystem Theories and Management, Joergensen S. E. and Mueller F., Eds. CRC Press, Boca Raton, 2000, pp. 561-576.
Karr J. D. 1993. Measuring biological integrity: lessons from streams, in Woodley S., Kay J., and Francis G., Eds., Ecological Integrity and the Management of Ecosystems, CRC Press, Boca Raton, FL, 1993, pp. 83-104.
Karr J. R. and Chu E. W. 1999. Restoring Life in Running Waters: Better Biological Monitoring: 1999, Island Press, Washington D.C. Retrieved from: www.springerlink.com
Lackey R. T. 2001. Values, policy, and ecosystem health, BioScience, 51: 437-444.
Maffi L. 2001. On Biocultural Diversity: Linking Language, Knowledge and the Environment, Smithsonian Institution Press, Washington, D.C.
Mueller F., Hoffmann-Kroll R., and Wiggering H. 2000. Indicating ecosystem integrity — theoretical concepts and environmental requirements. Ecological Modelling 130 (2000) pp. 13–23. Retrieved from: http://www.sciencedirect.com/
Nash R. 1994. Historical and Philosophical Considerations of Ecosystem Management. In: Ecosystem Management: Status and Potential, report of a workshop convened by the Congressional Research Service, March 24-25, Senate Committee on Environmental and Public Works, 103^rd Cong., 2^nd sess., December 1994, S. Prt. 103-98,3.
Norton B. G., Ulanowicz R. E., and Haskell B. D. 1991. Scale and Environmental Policy Goals. Report to the EPA, Office of Policy, Planning, and Evaluation. Washington: EPA.
Rapport D. J. 1991. Myths in the foundations of economics and ecology. Biol. J. Liimean Soc. 44: 185-202.
Rapport D. J., Regier H. A., and Hutchinson T. C. 1985. Ecosystem behaviour under stress. Amer. Natur. 125: 617-640.
Rapport D. J., Regier H. A., and Thorpe C. 1981. Diagnosis, Prognosis, and Treatment of Ecosystems under Stress. In G. W. Barret and R. Rosenberg, Stress Effects on Natural Ecosystems. New York: Wiley.
Rapport J.D, Rolston E.D, Qualset O.C, Damania B.A., and Lasley L.W. 2002. Managing for Healthy Ecosystems, CRC Press , Boca Raton, London New York Washington D.C.
Reidel C., Richardson J. 1995. Strategic Environmental Leadership in a Time of Change. Inaugural Donion Lecture. Syracuse: State University of New York, College of Environmental Science and Forestry.

back