Environmental Engineering Reference
In-Depth Information
approaches can be used to structure complex ecological phenomena (Jørgensen and
M
uller 2000). The methodologies are applicable in practically any discipline,
including social, technical and ecological systems. In this chapter we give a short
overview on backgrounds and fundamentals in system analysis and frontier views
of ecological theory and application. Furthermore, we explain important terminol-
ogies and introduce major techniques and strategies used in the system analytical
practice as a basis for the development of ecological models.
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4.2 Ecological Theory, Systems and Complexity
In former stages of development, systems analysis was seen mainly as an analytical
tool which was used to structure and survey smaller, as well as large interaction
networks (Forrester 1968). Later, it was used as a scoping approach in coordinating
the tasks to be done, in particular to coordinate interdisciplinary research groups
where different specializations contribute to a given task and where the facilitation
of an interdisciplinary understanding is essential (Patten 1959, 1975). However, it
seems necessary to mention that systems analysis is not a standardized procedure.
There are many different interpretations of system theory. We largely refer to the
approach originating from the works of Bertalanffy (1969, called “General System
Theory”) and in addition to the more recent Object-Oriented Systems Analysis (Hill
1996) that originated from computer programming.
In ecology, the transition from qualitative consideration to quantitative consid-
erations is largely due to the introduction of a systems perspective (Odum 1953,
1983; Meadows et al. 1972). With the epistemological underpinning developed in
the context of Bertalanffy's general system theory (Bertalanffy 1949, 1950, 1969)
the concept became widely applied also in biology. Ecological applications fre-
quently related to a systems interpretation as used in cybernetics (see: Patten 1975;
Patten and Odum 1981), and elaborated the implications for hierarchical structures
relevant in ecological systems (Odum 1971; Allen and Starr 1982; O'Neil et al.
1986). Odum (1977) points out that central concepts of ecosystem theory need to
adopt a holistic perspective to deal successfully with the complexity of the system
in focus. Applications cover all aspects of analysing and describing ecological
systems from short-term physiological processes, adaptive behaviour and reaction
to environmental conditions, to long-term evolutionary approaches.
4.3 What Is a System and What Is Systems Analysis
A system is an abstract, hierarchical construct of a set of elements, which is
considered to operate as an entity. When referring to any given system, we first
need to make a consistent distinction of what exactly belongs to the system and what
does not. With this first analytical step, the boundaries of the system are defined. The
different elements and their relations are specific for a particular system. The
elements can be involved in relations with other elements.
