openLandscapes - Ecosystem Theories

University of Kiel, Ecology Centre, Msc Environmental Science, a seminar paper
1st version completed 11/25/2009 by Forsythe Scott and Katharina Witte (forsythe_scott@hotmail.com and Incuba@web.de)
2nd version (adaptations, changes) 2010 by Dmitry Kasimov (dvkasimov@yandex.ru)
Status: completed

Ecosystem Theories: Orientor Theory

Abstract

The purpose of this paper is to clarify the interpretation of "orientor" concept and to point out the main values and fields that the orientor theory uses. In order to understand the context in which the orientor theory has been developed it is necessary to look at the sustainability approach and the other two theories that orientors are closely connected to - the theory of self-organization and the gradient theory.

Key words: orientor theory, ecosystem development, landscape ecology, ecosystem self-organization.

Content

1. Introduction

According to Müller F. and Fath B. (1998) the development of a system "seems to be oriented toward specific points or areas in the state space. The respective state variables which are used to elucidate these dynamics are termed orientors."

There are many interpretations and descriptions about what orientors are, but the one that appears to be most suitable is the following:

“Orientors are aspects, notions, properties or dimensions which can be used as criteria to describe and evaluate the system´s developmental stage “(Bossel H., 1992).

Looking at figure 1 below it becomes clear that the purpose of orientors is to guide an ecosystem to a certain state of attraction/ goal state or resulting state. They can also be looked at as state variables or a set of indicators that show how mature or well developed a system is over time or in a certain stage of development. As long as the orientor lies within a certain range of values, a development towards a specific goal, resulting state or attractor is ensured.

There are some basic theses (Müller F. et al., 1998), which characterize orientors:

Thesis A: During the development of ecosystems, important measurable properties are regulary optimized.

Thesis B: Ecological orientors can be used to distinguish system states and to characterize different systems.

Thesis C: One set of ecological orientors defines both, the structural and functional features of the investigated system. Thus, orientors can be used for a holistic ecosystems characterization.

Thesis D: Ecological orientors are based on thermodynamic principles. They indicate general properties of dissipative living systems. Therefore, they represent the potential for self-organization.

Thesis E: Ecological orientors indicate the degree of naturalness in ecosystems.

Thesis F: Ecological orientors are a good basis for finding usable indicators for ecosystem health, ecological integrity or sustainability.

Figure 1. Typical unit hierarchy structure (after T.L. Eichman 2007)

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2. The basic ecological orientors

There is a need for systems to react to the environmental properties of normal environmental state, scarce resources, variety, variability, change and other systems. Thus their structures and reaction mechanisms will be built up by some fundamental criteria or so called ‘basic orientors’.

The development of an ecosystem can be considred successful, if it is well adapted to its environment and its structure and functions reflect the particular features of the environment (Bossel H., 1998). But all the environments have some common properties, or basic orientors, which are identical for all complex adaptive systems. These properties order structure and functions of ecosystems and guide their behavior in the environment, providing a measure of ecosystem fitness and development in different environments.

According to Bossel H. (1998), the different basic ecological orientors are:

Existence: Attention to this orientor is necessary to insure the immediate survival and subsistence of the system in the normal environmental state.
Effectiveness: the system should on balance (over the long-term) be effective (not necessarily efficient) in its efforts to secure scarce resources from, and to exert influence on its environment.
Freedom of action: the system must have the ability to cope in various ways with the challenges posed by environmental variety.
Security: the system must be able to protect itself from the detrimental effects of environmental variability, i.e. variable, fluctuating, and unpredictable conditions outside of the normal environmental state
Adaptability: the system should be able to change its parameters and/or structure in order to generate more appropriate responses to challenges posed by environmental change.
Coexistence: the system must be able to modify its behavior to account for behavior and orientors of other systems in its environment.
Psychological needs: for sentient beings, we must add this as an additional orientor.

The basic statement that Bossel wants to deliver is that the more these basic orientors are fulfilled by a system, the fitter and further developed it is.

Orientors are built up by a set of indicators and are used mainly in ecology. On a scale of how high an orientor is fulfilled, the distance to an optimum stage of development can be named as an indicator. It has to be taken into consideration that every orientor stands for an unique requirement which cannot be compensated by over-fulfillment of another orientor, but it can happen that sacrifices have to be made in one orientor to support the other.

While evolving in a normal environment, an ecosystem has to ensure minimum or balanced satisfaction of each of the basic orientors (Bossel H., 1998), as its health and fitness depends on it.

To illustrate a whole set of indicators and to which extent they are fulfilled, the so called orientor stars are very useful. Figure 2 shows the basic ecological orientors and how the orientor stars look if there is an emphasis on a specific orientor (“Generalist”, Cautious Type” and “Specialist”).

Figure 2. Orientor stars showing different basic orientor emphases (Bossel H., 1998)

Each of these three paticular "lifestyles" stresses different key orientors (Bossel H., 1998). Generalists emphasize the freedom of action orientor. They have adequate performance in their trained environment and can maintan this performance even for very significant increases of variety. Specialists stress the effectiveness orientor. They are adapted to their environment and are doing well in it, but they quickly lose their fitness in case of variety or variability increasing. Key orientor for "cautious type" is the security one. They perform even in their trained environment very low and can tolerate environment variety augment, but their chances to survival in an unknown environment are higher than for other types.

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3. Use and value of orientor theory

In science some central questions arose, dealing with orientors, for example: Can certain regularly appearing attractors and system-based orientors be defined during ecosystem development? Can we use orientor principles in environmental management? The use and value of orientor theory are that it provides a comparable series of constellations so that similar changes of certain attributes can be observed in different environments. For example, we can use ecological modeling to investigate the development of certain orientors in different situations (different species composition).

The task of providing about the developmental stage of an ecosystem or a landscaspe and describing orientor dynamics is a rather complicated one. As the number of elements and processes that can be measured or modeled is limited, applicable assessments have to be based on a selected set of manageable indicators, representatives for the system in focus. Respective indicators have to be represented by variables, which are accessible by traditional ecological methods of quantification and to denote ecosystem processes (energy, matter, water budgets or cycling) and structures (biotic and abiotic components) as a whole in order to assess and evaluate the system's stage of self-organization. This set of indicators should be based on the focal variables which are usually investigated in ecosystem research and which can be made accessible in comprehensive monitoring networks (Müller F., 2005).

The basic statement of Spangenberg (2007) is that orientors are conditions that we can apply to (eco)systems in order to judge their sustainability. In each case, we are asking, how much does the system exhibit "ability for continuous existence and reproduction, co-existence with other associated ecosystems, resilience against disturbance, adaptability to changes in the environment, effectiveness in providing natural resources and how are environmental, economic, resource, or human cost requirements".

The fulfillment of each condition should be measurable by use of indicators, and then plottable on a so-called "amoeba" diagram, for instance, as shown in Figure 3.

In this example, the development of two different ecosystems is depicted: alder carrs and wet grasslands. In this case, drainage and eutrophication are compared to the former, more natural state with wet and mesotrophic conditions, while some indicators with high values stand for negative (N-leaching) and some for positive (species number plants) development.

Figure 3. The development of alder cars and wet grasslands in the wild and after drainage.

As in the figure, the development of the nitrogen and carbon balances demonstrates that the system is turning from sink function into a source, the storage capacity is being reduced, and the loss of carbon and nitrogen compounds (high mineralization rates, high nitrate output by leaching and high nitrogen loss through denitrification) is rising enormously. Due to these dynamics we can give a qualitative estimation of these processes and state that there has been an enormous decrease of ecosystem integrity (Müller F. et al., 2010).

We can see from this example, that orientor approach has been proposed as indicating criteria of ecosystem states (Müller F. and Leupelt M., 1998), in order to decribe and evaluate ecosystem's developmental stages and their varying properties, taking into consideration inherent uncertainties (instable reactions and unpredictability of ecosystem states).

After disturbances, for example climatic changes, invasive species, droughts, etc., the orientor values might decrease rapidly (Figure 4) in case of high external inputs (Müller F., 2005).

Figure 4. Reactions of different systems after disturbances (Müller F., 2005).

This figure shows that an adaptive or resilient sytem will rather soon find the optimisation trajectory again, while a heavily disturbed ecosystem might no more be able to improve the values of the orientors. Hereby orientors can be used to depict the resilience of ecosystem features by the degree to which they are able to follow the orientor trajectory after disturbances. Therefore, the robustness of ecosystems can be indicated by the orientors as well (Müller F., 2005). Consequently, the orientors' values are also suitable to represent the ecological risk, which is correlated to external inputs or changes of the prevailing boundary conditions (Müller F. et al., 2008).

Orientors should be grouped, because not every human being has the same wish how an ecosystem should look like or what its purpose should be. Due to the large number of different interest groups, directly involved in planning and decision-making processes, several various points of view have to be taken into consideration (Gnauck A., 1998). According to this author, a single objectively derived best solution does not generally exist. Depending on investigating dynamics and processes, different types of orientors have been defined (Müller F. et al., 2010), such as thermodynamic orientors (e.g. capture, flow and storage of exergy), network orientors (e.g. cycling index, chain lenght), ecophysiological orientors (e.g. loss reduction, flux density, internal flow cycling, respiration), community orientors (e.g. niche diversity, symbiosis, selection) and ecodynamic orientors (Figure 5).

Figure 5. Types of orientors (Müller F. et al., 2010)

This differentiation brings a lot of other scientific fields or disciplines closer to the orientor theory: in the social part - social sciences and philosophy, for the economic part - business administration and statistics; the environmental part is connected with environmental sciences in general, which are splitted into numberless small sub-disciplines.

As we could see, with the help of orientors' dynamics general developmental trends of ecosystem features can be detected, understood and forecasted. The example given above showed that it is possible to indicate ecosystem integrity, thus to characterize the state of an ecosystem and to depict resilience or adaptability on the base of ecosytem data and indicator sets. If needed, a comparison of the actual developmental stage with an observer-defined (normative) mature or target stage can be made. By doing so, estimations of potentials for future self-organization can be suggested (Müller F. et al., 2010).

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4. Other approaches to orientor theory

Ever since orientor theory was developed it had a strong connection to the principle of sustainability or sustainable development, which has a lot of definitions, but the most frequently quoted one is the following: "Sustainable development is development that meets the needs of the present generations without compromising the ability of future generations to meet their own needs" (International Institute for Sustainable Development).

According to F. Müller (2005), it is possible to use an alternative formulation for the ecological components of suatainable develpment: "meet the needs of future generations" in this context means "keep available the ecosystem services on a long-term, intergenerational and a broad scale, intragenerational level".

Ecosystem development provides various benefits that people obtain and utilize: natural resources (food, oxygen, fuel, etc.), cultural attributes (aesthetics, education, and history), regulating functions (climatic regulation, energy, water and matter budget regulations, etc.). These benefits or in other words "ecosystem services" are strictly dependent on the degrees and the potentials of the fundamental self-organizing (Müller F., 2005).

These organizing processes can operate without consciously regulating influences from the system's environment. That is why the development of ecosystems is assigned to the category of self-organization processes which actually are constrained by human activities (Nielsen S. and Müller F., 2000). This means, that environmental self-organizing processes can be regarded as basic ecological requirements for the provision of ecosystem services and, as consequence, sustainable development strategies. To ensure this, the ability for future self-organizing processes within the respective system has to be preserved (Kay J., 1993).

The processes of ecological self-organization are situated in the focus of the orientor principle (Nielsen S. and Müller F., 2000). Creating macroscopic and microscopic disorder self-organized ecological systems can produce structures and gradients if they receive an input of usable energy in the form of solar radiation or so-called exergy through-flow (Joergensen S.,1992). The emergence of a hierarchical system of complex, small, and interconnected gradients leads to the formation of structures that dissipate the exergy more and more efficiently. As the result of self-organizing processes, this increasing complexity will reduce the probability of collapse, which is a plausible consequence of the steep external gradients the system is exposed to (Müller F., 1996. In: Kutsch W.L. et al., 1998).

Pursuant to Müller F. (2005), under certain circumstances gradients (structures) are built up and maintained as a result of these energy conversion processes. These characteristics or features are increasing steadily and slowly and developing towards a certain attractor state, which is determined by the specific site conditions and which is a result of the prevailing ecological functions. Using this ecosystem features as indicators, the naturalness of an ecosystem's development can be depicted.

The concept of ecological gradients is based upon the thermodynamic non-equilibrium principle. According to the principle, self-organizing ecological systems build up an internal, hierarchical system of interconnected gradients as a consequence of external exergy gradient provided by solar radiation (Joergensen S. and Müller F., 2000). Therefore these gradients (for example, nutrient fluxes, carbon pools, oxygen content, etc.) can be regarded as emergent properties of ecosystems (Nielsen S. and Müller F., 2000).

Thus, generally speaking, gradients are ecological orientors and can be applied as indicators of ecosystem development (Müller F. et al., 2008).

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5. Diverging interpretations and discussion

Due to the many scientific fields dealing with orientor theory, there are also a huge variety of hypothesis about why and how to use orientors for the analysis of ecosystem development (Müller F. et al. 1998). Hence, there is a lack of clarity or unity in the basic terms that are used when discussing orientor theory. Even in one and the same article more than one definition can be found:

“[The orientor approach] refers to the idea of self-organizing processes, that are able to build up gradients and macroscopic structures from the microscopic „disorder“ of non-structured, homogeneous element distributions in open systems, without receiving directing regulations from the outside” (Müller F. and Fath B., 1998).
The respective state variables which are used to elucidate these dynamics, are termed orientors. Their technical counterparts in modeling are called goal functions (Müller F. and Fath B., 1998).
“The term ‘orientor’ is used to denote (explicit or implicit) normative concepts that direct behavior and development of systems in general. In the social context, values and norms, objectives and goals are important orientors. Ecosystems and organisms pursue certain goal functions as orientors (Müller F., 1996) […] Orientors are ‘dimensions of concern’; they are not specific goals.”(Bossel H., 1998).
(Bossel H., 1992) "The corresponding ecological state variables will be called orientors in this text, reflecting the fact that their dynamics seems to be oriented toward certain attractor points."

We find orientors used interchangeably with goals, goal functions, management goals, thermodynamic states, etc. and assume that this is the reason why there are so many terms and attempts of definitions.

We interpret that they all wish to convey the idea that there are principles guiding observed (eco)system development and appreciate that there is a need to determine ‘ecosystem guiding principles’ and that this can be rather difficult. The problems of terminology are also mentioned by the authors themselves (Müller F. and Leupelt M., 1998).

Some authors state (Herrmann S. and Zölitz-Möller R., 1998) that orientors appear to be more of an idealistic picture of the desirable state of ecosystems and to be designed within more theoretical (modeled) worlds of ideas. With respect to these authors, in order to use the orientor concept for planning and environmental management purposes, a list of indicators must be provided, which have to be easily adaptable in practice and for different scales and to be adequate for the quantification of the ecosystem actual state quality.

Nevertheless. the developmental tendencies can be observed by means of orientors (Müller F. et al., 1998), which on the one hand, avoid the usual restrictions to structural units by integrating the important functional ecosystem elements and, on the other hand, include indirect, chronic and delayed effects and impacts into evaluation procedures.

As a conclusion we can say that orientors are consequences of Darwinian evolution on the ecosystem level. In Darwin's thoughts the varying conditions of existence are the main cause for the differences between parents and their offspring. Furthermore, it is not the individual or an ecosystem which chooses to adapt to certain conditions, it is its fitness and it is natural selection which chooses the fittest individuals (http://www.biologie.uni-hamburg.de/b-online/e36/36b.htm).

Orientors can thus be seen as ecosystem features which become more and more complex over time. In this context the so called emergent properties should be mentioned. As every kind of system ecosystems are made up of components. Once those components are integrated into the system, they take on the properties of the system. Emergent properties in an ecosystem would be things like nutrient cycling or energy flow.

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6. Conclusion

The orientor approach to analysis of succession in specific ecosystems, based on hypotheses about the effects of ecosystem component changes on ecosystem development, enables one to tie the many complex behaviors, interactions and developments of an ecosystem together into easily handled and monitorable "bundles" of information from which management conclusions can be drawn (for an example see Figure 3). This is especially useful in landscape management, where particular landscapes sharing ecosystems with common features are preferred and for which management schemes are sought.

The ‘amoeba diagram’ is an especially useful tool for portraying ecosystem changes and results to non-scientific or policy-making audiences. The orientor approach gives us therefore both an analytic as well as a prognostic tool for ecosystem management. It can be imagined, that in the future, as experience and knowledge about ecosystem response and development increase, as techniques for monitoring ecosystem components improve, that this particular employment of ecosystem theory will become commonplace among managers and decision-makers.

So far as ecological systems are characterized by a very high capability for self-organization and have been evolving for billions of years it makes sense to use and apply the orientors's signals in practical management of a more near-nature manner, that can prove to be a profound and promising strategy and contribute to the ecological goals of sustainable development (Müller F. et al., 1998).

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References

Bossel H. (1992). Modellbildung und Simulation – Konzepte, Verfahren und Modelle zum Verhalten dynamischer Systeme. Braunschweig.
Bossel H. (1998). Ecological Orientors: Emergence of basic orientors in evolutionary self-organization. In: Müller, F. and Leupelt M. (1998): Eco targets, goal functions, and orientors. Berlin. Heidelberg. pp. 19-33.
Gnauck A. (1998). Applying Ecological Goal Functions: Tools for Orientor Optimization as a Basis Decision making Processes. In: Müller F. and Leupelt M. (1998): Eco targets, goal functions, and orientors. Berlin. Heidelberg. pp. 511-525.
Herrman S. and Zölitz-Möller R. (1998). Conclusions: Potentials and Limitations of a Practical Application of the Ecotarget and Orientor Concept. In Müller F. and Leupelt M. (1998): Eco targets, goal functions, and orientors. Berlin. Heidelberg. pp. 585-590.
Joergensen S.E. (1992). Integration of Ecosystem Theories - A Pattern. Kluwer Academic Publishers, Dortrecht.
Joergensen S.E. and Müller F. (2000). Handbook of Ecosystem Theories and Management. CRC Press LLC. Boca Raton. p. 568.
Kay J.J. (1993). On the nature of ecological integrity: Some closing comments. In: Woodley S., Kay J., Francis G. (Eds.). Ecological Integrity and the Management of Ecosystems. St. Lucie Press. Delray. Florida. pp. 210-212.
Kutsch W.L., Dilly O., Steinborn W. and Müller F. (1998). Quantifying Ecosystem Maturity - a Case Study. In Müller F. and Leupelt M. (1998): Eco targets, goal functions, and orientors. Berlin. Heidelberg. pp.208-231.
Müller F. (2005). Indicating ecosystem and landscape organization. Ecological Indicators 5 (2005). pp. 280-294.
Müller F., Barkmann J., Breckling, B. Leupelt M., Reiche E-W. and Zölitz-Möller R. (1998). Targets, Goals and Orientors: Concluding and Re-Initializing the Discussion. In Müller F. and Leupelt M. (1998). Eco targets, goal functions, and orientors. Berlin. Heidelberg. pp. 593-607.
Müller F., Burkhard B. and Kroll F. (2010). Resilience, Integrity and Ecosystem Dynamics: Bridging Ecosystem Theory and Management. Lecture notes in Earth science. Springer-Verlag. Berlin. Heidelberg. pp. 241-242.
Müller F. and Fath B. (1998). The physical basis of ecological goal functions - fundamentals, problems and questions. In: Müller F. and Leupelt M. (1998): Eco targets, goal functions, and orientors. Berlin. Heidelberg. pp 13-18.
Müller F., Fränzle O. and Schimming C. (2008). Ecological gradients as causes and effects of ecosystem organization. In Ecosystem organization of complex landscapes. Springer Berlin. Heidelberg. 202. pp. 277-294.
Müller F. and Leupelt M. (1998): Eco targets, goal functions, and orientors. Berlin. Heidelberg.
Müller, F., Leupelt, M., Reiche, E.-W. and B. Breckling (1998): Targets, Goals and Orientors. In: Müller, F. & M. Leupelt (1998): Eco targets, goal functions, and orientors. Berlin. Heidelberg. pp. 3-11.
Müller F. and Nielsen S.N. (2000). Ecosystems as subjects of self-organizing processes. In: Joergensen S.E. and Müller F. (Eds.).: Handbook of Ecosystem Theories and Management. CRC Press LLC. Boca Raton. pp.177194.
Nielsen S.N. and Müller F. (2000). Emergent properties of ecosystems. In Joergensen S.E. and Müller F. (Eds.): Handbook of Ecosystem Theories and Management. Boca. Raton. pp. 195-216.
Spangenberg (2007): Biodiversity pressure and the driving forces behind. In: Ecological Economics, Vol. 61, p. 146-158.

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Useful links

Bossel, H. (2001): Assessing Viability and Sustainability: a Systems-based Approach for Deriving Comprehensive Indicator Sets. Conservation Ecology 5(2): 12. Online: http://www.ecologyandsociety.org/vol5/iss2/art12/
Botany online: Evolution: Charles Darwin´s life. http://www.biologie.uni-hamburg.de/b-online/e36/36b.htm
International Institue for Sustainable development. http://www.iisd.org/sd/.
Krebs, F.and Bossel H. (1997): Emergent value orientation in self-organization of an animat. In: Ecological Modelling 96, p. 143-164.
Lodge, T. (2004): The Everglades Handbook. Understanding the Ecosystem.
Müller, F., Schrautzer, J., Reiche, E.-W. and Rinker, A. (2005): Ecosystem based indicators in retrogressive successions of an agricultural landscape. Online: www.elsevier.com/locate/ecolind.
Schrautzer J., Rinker A., Jensen K., Müller F., Schwartze P. and Dierßen K. (2007): Succession and Restoration of Drained Fens: Perspectives from Northwesten Europe. In: Wlaker L., Hobbs R.J. and Walker J. (Eds.). Linking Restoration and Ecological Succession, Springer Series on Environmental Management. pp. 90-120.
United Nations (1987): Report of the World Commission on Environment and Development, General Assembly Resolution 42/187, 11 December 1987. Retrieved: 2007-11-14.

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