Environmental Engineering Reference
In-Depth Information
Fig. 2.5 Hierarchichal levels, which are distinguished as organization levels. Ecological model-
ling deals with individuals, populations, ecosystems, landscapes, and biomes. Still lower levels,
from the biomolecule up to the individual, are the domain of physiology; however, sometimes
these are also included in models along with ecological levels of interactions
effects these properties have on dispersal in differently structured landscapes
(Fig.
2.6
right
). Depending on the distribution of suitable and less suitable habitats,
the model can provide results of how individual behaviour and landscape dispersal
patterns relate over the long run.
This field of ecological analysis should not be dealt with by
expert's intuition
alone. In this regard, models allow an extension of conclusions beyond what is
accessible in direct empirical investigations. With appropriate model approaches it
can be studied how components of a level-crossing interaction network influence
each other. For instance, Chap. 18 illustrates how trophic pyramids and trophic
cascades of a wetland ecosystem (Everglades) are affected by hydrological changes.
Models Can Illustrate Iterative and Feedback Processes
In ecological models interactions between elements are in most cases specified in a
computer programme and executed on a computer. The rationale behind this is that
the number of repeated executions of all steps can be several orders of magnitude
higher than what can be done by manual calculation. Modelling has special merits
when feedback or iterative processes are involved: If we know the elementary
interactions - what will be the result if they re-occur 10, 1,000 or 100,000 times? In
linear cases, sometimes mathematical calculations can directly lead to a precise
