Environmental Engineering Reference
In-Depth Information
Chapter 2
What Are the General Conditions Under
Which Ecological Models Can be Applied?
Felix M
€
uller, Broder Breckling, Fred Jopp, and Hauke Reuter
Abstract The purpose of this chapter is to discuss the conditions under which models
can be applied. Modelling can help to solve specific problems, but not all questions in
ecology require or benefit from the application of a model. It is therefore necessary to
have an idea about the criteria under which the development of a model can provide
useful information or help to solve questions in ecological analysis and which concep-
tual and technical approaches are the most appropriate ones. Technical knowledge about
the particular modelling techniques is presented in the subsequent chapter of this topic.
Here,weintendtogiveanoverviewofthebasic criteria of model application.
2.1 Models as Instruments of System Analysis
Models are abstractions of reality and instruments for the survey and analysis of
complex systems (Wainwright and Mulligan 2004; Dale 2003). They are used to
reduce the complexity of systems with reference to the specific problem that the
observer wants to solve. Ecological models can depict the interactions and changes
of environmental elements and simulate the dynamics of spatial and temporal
patterns in ecosystems. Thus, they are instruments of environmental systems
analysis (Bossel 1992; Gnauck 2000; Hannon and Ruth 2001).
A fundamental system comprehension should be considered as an initial con-
ceptual condition for successful modelling. Ecological systems are complexes of
biotic and abiotic elements, which are interrelated by flows of energy, matter and
information (Breckling and Muller 1997). These interactions build up a compre-
hensive and complicated network of heterogeneous direct and indirect effects (Fath
and Patten 2000). This network has an extraordinary high connectivity and its
complexity rises drastically with the number of elements, relations and nonlinear
interactions (Salthe 1993; Grant and Swannack 2007). This has the implication that
