Environmental Engineering Reference
In-Depth Information
New approaches additionally facilitate the potential to work with flexible inter-
action networks, where the number of elements and the way they are connected can
change (see Chap. 11 on L-Systems, and Chap. 12 on Individual-based models). This
poses high challenges to the conceptual development of simulation frameworks,
especially if not only the involved quantities change in a nonlinear way, but also the
structure changes in the course of interactions. This can be the case in modelling the
structure and physiological processes in plants (see e.g. Figs.
4.3
and
4.4
).
Models Can Facilitate an Understanding of Multi-Scale
Problems in Ecology
Phenomena that involve several orders of magnitude in scales are usually difficult
to handle. There are examples where model approaches can help to deal with large-
scale issues that depend on very small scale interactions.
Nutrient budgets on the landscape level are an example (see Fig
2.7
). Here
initially the soil physicochemical potentials of different sites are used to calculate
local nutrient flows, representing e.g. a patch scale. If the modelling question is
Fig. 2.7 Nitrogen leaching in the Bornhoved Lakes landscape simulated with the WASMOD
modelling system (Reiche 1996).
Left
: The measured nutrient retention capacity of different soil
types has been taken to calculate a business-as-usual scenario with a dominant small-farm
structure.
Right
: Simulation of different scenarios: (a) Industrial agriculture - a structure with
big farms and efficient land use practice leads to a change in land cover and land-use, providing an
overall reduction of nitrogen leaching amounts. (b) Green agriculture - due to the reduced use of
fertilizers and due to reduced pressures, i.e., on poor soils the nitrogen flows into the groundwater
are heavily reduced
