BCSSS

International Encyclopedia of Systems and Cybernetics

2nd Edition, as published by Charles François 2004 Presented by the Bertalanffy Center for the Study of Systems Science Vienna for public access.

About

The International Encyclopedia of Systems and Cybernetics was first edited and published by the system scientist Charles François in 1997. The online version that is provided here was based on the 2nd edition in 2004. It was uploaded and gifted to the center by ASC president Michael Lissack in 2019; the BCSSS purchased the rights for the re-publication of this volume in 200?. In 2018, the original editor expressed his wish to pass on the stewardship over the maintenance and further development of the encyclopedia to the Bertalanffy Center. In the future, the BCSSS seeks to further develop the encyclopedia by open collaboration within the systems sciences. Until the center has found and been able to implement an adequate technical solution for this, the static website is made accessible for the benefit of public scholarship and education.

A B C D E F G H I J K L M N O P Q R S T U V W Y Z

DISTURBANCE 1)

1. "That which displaces, … moves a system from one state to another (W.R. ASHBY, p.77, 1956).

2. "Any relatively discrete event in time that disrupts ecosystem, community or population structure, and changes resources availability of substratum, or the physical environment" (St. PICKETT & P. WHITE, 1985 – as quoted by S. REICE, 1994, p.427).

While ASHBY's definition is more general, the second one is more useful in relation to concrete systems.

REICE states: "This description defines disturbance as a physical event, not as the biotic outcome of the event. I view a disturbance as a physical force such as a fire, flood or tornado that damages natural systems… The first impact of a disturbance is always to remove organisms" (Ibid).

This concept can easily be extended to an ample variety of human systems.

REICE adds various interesting comments: "Disturbance is scale dependent. If the area studied is large enough or the period of observation long enough, all disturbances are predictable and "normal" (Ibid). This means, of course, relatively predictable"

Still: "At smaller scales or shorter durations, disturbances appear completely random" (Ibid).

Moreover: "The absence of predictable disturbances (for example, spring snowmelt floods, or the arrival of snow in winter) often has a greater impact than their presence"(Ibid).

REICE refers himself to "disturbance regimes", which may command frequent, intermediate or only long term disturbances. Under the former one, "…the dominant competitors are reduced or eliminated, and colonizing species (assumed to be inferior competitors) dominate the system " and, " …under a disturbance regime that is intermediate in frequency, magnitude and intensity, some resident species persist in the system, along with colonizing species, which exploit the disturbed areas. Thus intermediate disturbance leads to maximum species richness" (Ibid., p.428).

Finally, long delayed disturbances tend to lead the system to a kind of ageing, with decrease of variety (diversity).

However, "Disturbance per se does not determine diversity. It (only) creates opportunities for colonization of vacated spaces by new species" (p.431) … of course if these are available from other zones.

Moreover: "Spatial heterogeneity and disturbance are interdependent. Disturbance creates patches, but patchiness modifies and sets the extent of the disturbance, – that is disturbance responds to the underlying heterogeneity of the environment" (p.434).

Generally speaking systems show adaptability to disturbances.

A last important aspect is that : "In some systems the return frequency of disturbance is so long that the impression of equilibrium conditions develops. This is what underlies the traditional idea of climax communities".

These very significant models should be pondered by anybody who wants to interfere with natural ecosystems. Their validity should as well be considered for modelling disturbances of human systems and their reactions to these.

It is important to note that disturbances can be endogenous or exogenous, even if an environmental disturbance is generally the remote or direct cause of the endogenous one.

Categories

  • 1) General information
  • 2) Methodology or model
  • 3) Epistemology, ontology and semantics
  • 4) Human sciences
  • 5) Discipline oriented

Publisher

Bertalanffy Center for the Study of Systems Science(2020).

To cite this page, please use the following information:

Bertalanffy Center for the Study of Systems Science (2020). Title of the entry. In Charles François (Ed.), International Encyclopedia of Systems and Cybernetics (2). Retrieved from www.systemspedia.org/[full/url]


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