Environmental Engineering Reference
In-Depth Information
General Systems Theory An interdisciplinary approach for explaining complex
phenomena by their system's character, founded by the biologist Ludwig von
Bertalanffy, closely related to
!
cybernetics
.
Generic Model A model that describes general properties of an ecological
system and can be easily adapted to different specific situations.
Goal Functions In the ecological context adapted principles from thermodynamics
to describe systems being far from equilibrium and which have the tendency to
develop towards a particular state.
Hierarchy Theory This was derived from
general systems theory
to deal with
complexities in a system that is spanned over a range of hierarchical interacting
levels in space and time. For ecology, these principles were successfully adapted
since the works of Allen and Starr during the 1980s.
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Hysteresis For systems with a memory effect, the strong correlation between
input signal and output reaction can be impaired. Then, multiple systems' states can
shift rapidly from one state to another. As a consequence, predictions for future
time intervals might be impossible.
Inference This (in logic) is the transition from premises to conclusion, in such
a way that they are logically connected. The typical form of the logical connection
for inference is the so-called modus ponens: “if p then q”: premises are taken and
a conclusion is returned. If the premises are true, they guarantee the truth of the
conclusion. An inference system is composed by a set of “if...then” rules, and it
provides the support for mapping from a given input to an output.
Information Criteria Measure of the goodness of fit of a statistical model which
formally describes the relation between model complexity and accuracy. Some
examples are the Akaike's information criteria (AIC), the area under the curve
(AUC), the coefficient of determination (R2), or the Nash-Sutcliffe model effi-
ciency coefficient.
Intermediate Disturbance Hypothesis Concept that hypothesizes that local
species diversity is highest for intermediate levels of disturbance; because very
low disturbance levels favour competitively superior species, whereas exception-
ally high disturbance levels increase the risk of extinction for most of the species.
Lacunarity Analysis Statistical analysis to describe the scale-dependent distri-
bution of gap sizes.
Landscape Fragmentation A major threat to local biodiversity relates to the
fragmentation of former coherent habitats as population size may fall below a
critical threshold and dispersal and exchange between populations may be reduced
or prevented.
