Ecology Center

Orientors as Implicit Attractors

Better orientor satisfaction (better fitness) for more participants in a system requires more dissipative structure, which requires more exergy throughput as well as exergy accumulation. Since the exergy flow of ecosystems is limited (capture of solar radiation by photoproduction), increasingly better utilization is to be expected in the course of system development. This saturates at maximum exergy flow utilization for the ecosystem as a whole. Ecosystems as a whole therefore move in the direction of using all available exergy gradients. For organisms in the ecosystem, this implies development tendencies (orien-tors, propensities, attractors) toward specialization (using previously unused gradients), more complex structure (greater use efficiency), larger individuals (less maintenance exergy required per biomass unit), mutualism, etc. For species development, this translates into a principle of maximum exergy use efficiency. On the basis of these principles, prediction of development trends in ecosystems is possible.

The selection for better fitness in evolutionary processes favors systems (organisms) with better coping ability. Aspects of the behavioral spectrum of a system that improve coping ability (basic orientors) can be understood as implicit goals or attractors: existence,

Table 1 Orientor concepts in the context of ecological succession

Developmental Mature stage stage

Basic orientor emphasis

	Existence	Coexistence
	Freedom	Security
	Effectiveness	Adaptability
Ecosystem orientor	Orientor emphasis (goal function)
Growth and change	High	Low
Life cycle	Short, simple	Long, complex
Biomass	Low	High
Energy conservation	Low	High
Nutrient conservation	Low	High
Nutrient recycling	Low	High
Specialization	Low	High
Diversity	Low	High
Organization	Low	High
Symbiosis	Low	High
Stability; feedback	Low	High
control
Structure	Linear, simple	Network,
		complex
Information	Low	High
Entropy	High	Low

security, effectiveness, freedom, adaptability, coexistence. In the developmental stage of ecosystems, emphasis is on the basic orientors: existence, effectiveness, and freedom; in the mature stage it shifts to security, adaptability, and coexistence (see Table 1, where orientor concepts have been linked to E. P. Odum's classical model of ecological succession).

The existence of these implicit goals does not imply teleologic or teleonomic development toward a given goal (where the final state is specified). These attractors do not determine the exact future states of the system at all; they only pose constraints on choices (or evolutionary selection). The process and its rules are known, the product is unknown. The spectrum of (qualitatively different) possible future development paths and sustainable states remains enormous. The shape of the future, and of the systems that shape it, cannot be predicted this way. All one can say with certainty, however, is that (1) all possible futures must be continuous developments from the past, and (2) paths with better orientor satisfaction are more likely to succeed in the long run (if options to change paths have not been foreclosed).

In many systems, in particular ecosystems, specific attractors or functional orientors are often more immediately obvious than the basic orientors that cause the emergence of these orientors in the first place. These orientors can be viewed as appearing on a level below the basic orientors in the hierarchical orientation system (see Table 1 ). They translate the fundamental system needs expressed in the basic orientors into concrete attractor states linking system response to environmental properties. In models and ecosystem analyses, measures of ecosystem integrity can be based on corresponding ecosystem goal functions. Ecosystem attractor states emerge as general ecosystem properties in the coevolution of ecosystem and environment. They can be viewed as ecosystem-specific responses to the need to satisfy the basic orientors. Major ecosystem orientors are optimization of use of solar radiation, material, and energy flow intensities (networks); matter and energy cycling (cycling index); storage capacity (biomass accumulation); nutrient conservation, respiration, and transpiration; diversity (organization); hierarchy (signal filtering).

The emergence of basic orientors in response to the general properties of environments can be deduced from general systems theory, but supporting empirical evidence and related theoretical concepts can also be found in such fields as psychology, sociology, and the study of artificial life.

Orientor Guidance in System Development, Control, Adaptation, and Evolution

Environmental influences partially determine system behavior. The magnitude of their effect on behavior depends on the influence structure of the system.

Sometimes systems can be controlled by controlling the inputs from their environment. However, the feedbacks in the system itself are usually more important for system control and adaptation of behavior to environmental conditions. Feedback means that the system state influences itself. Behavior-changing internal feedbacks are possible on several hierarchical levels in complex systems with different typical response characteristics and time constants (typical response times). These possibilities are also shown in Figure 3.

Response time	Level	Response
Immediate	Process	Cause-effect
Short	Feedback	Control
Medium	Adaptation	Parameter change
Long	Self-organization	Structural change
Very long	Evolution	Change of identity
Always	Basic orientors	Maintaining integrity

The simplest type of system response is the cause-effect relationship. It occurs at once as in for example, stimulus-response reflex. It is the only type of system behavior which can legitimately be described by relating the output directly to the input. Unfortunately, it is often assumed that the same simple relationship is also applicable to other types of system response (such as the following), and this erroneous assumption often leads to fundamental mistakes.

On the next higher level we find responses which are generated by feedback in the system, involving at least one state variable or delay - such as an empty stomach causing hunger and the search for food. Control processes belong to this category. The response time is short, and influence structure and system parameters remain invariant.

On the next higher level we find processes of adaptation. In this case the system maintains its basic influence structure, but parameters are adjusted to adapt to the situation, possibly changing the response characteristics in the process. For example, a tree may adapt to the gradual lowering of the groundwater level by growing its roots to greater depth. This constitutes a parameter change (root length and root surface). The fundamental

Integrity

Evolution

Self-organization

Adaptation System input

Integrity

Evolution

Self-organization

Adaptation System input

System output

Stimulus response

Figure 3 System response can be caused by different processes with very different time constants: stimulus-response, feedback control, adaptation, self-organization, evolution, maintaining system integrity.

System output

Stimulus response

Figure 3 System response can be caused by different processes with very different time constants: stimulus-response, feedback control, adaptation, self-organization, evolution, maintaining system integrity.

system structure of a tree, in particular, the function of the roots, has not changed in this case.

On the next higher level we find processes of self-organization in response to environmental challenges. This means structural change in the system. Processes of this kind have a longer response time and can only be conducted by systems having the capability for self-organization. Adult organisms or technical systems rarely or never belong to this category; on the other hand, this characteristic is often found in the development of organisms, social systems, organizations, and ecosystems.

A system may also change its identity in the course of an evolutionary process. This means that its functional characteristics, and hence its system purpose, change with time. Adaptations of this kind take place as a result of reproduction and evolution of living organisms. It is characteristic of this process that the system change coincides with a possibly drastic shift in system identity (change of goal function and of system purpose). An evolutionary example is the development of flying animals (birds) from water-dwelling reptiles.

All of these system responses to challenges from the environment in essence constitute attempts to maintain system integrity (possibly over many generations and over a long time period) even if it means changing system identity, that is, system purpose. From this observation it can be deduced that a system must orient its development with respect to certain basic criteria (basic orientors) to assure its long-term existence and development in an often hostile environment. This orientation may be implicit (forced upon the system) or explicit (actively pursued by the system). It does not require conscious decision or even cognitive ability, although resulting action may appear to an observer as intelligent or even goal- or value-oriented behavior.

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