On the Ecology of Mountainous Forests in a Changing Climate: A ...
On the Ecology of Mountainous Forests in a Changing Climate: A ...
On the Ecology of Mountainous Forests in a Changing Climate: A ...
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The forest model FORCLIM 89<br />
All <strong>the</strong> simulation studies with <strong>the</strong> FORCLIM model were run on Apple Mac<strong>in</strong>tosh computers,<br />
us<strong>in</strong>g <strong>the</strong> computer models SE/30 (CPU Motorola 68030, FPU Motorola 68882),<br />
IIfx (68030/68882) and Quadra 700 (68040, with <strong>in</strong>tegrated FPU). For efficiency<br />
reasons, <strong>the</strong> object code <strong>of</strong> all <strong>the</strong> models was generated us<strong>in</strong>g <strong>the</strong> Compile20 option <strong>of</strong><br />
<strong>the</strong> MacMETH environment (Wirth et al. 1992), which produces code that addresses <strong>the</strong><br />
ma<strong>the</strong>matical coprocessor directly, thus bypass<strong>in</strong>g <strong>the</strong> much slower Standard Apple<br />
Numerical Environment (SANE).<br />
3.5.2 Coupl<strong>in</strong>g <strong>the</strong> submodels<br />
The three submodels FORCLIM-E, FORCLIM-P, and FORCLIM-S each were implemented<br />
as ModelWorks models <strong>of</strong> <strong>the</strong>ir own (Fischl<strong>in</strong> et al. 1990). <strong>On</strong>e important aim <strong>of</strong> <strong>the</strong><br />
model implementation was that <strong>the</strong> behaviour <strong>of</strong> each <strong>of</strong> <strong>the</strong> three submodels can be<br />
studied irrespective <strong>of</strong> whe<strong>the</strong>r one or both <strong>of</strong> <strong>the</strong> o<strong>the</strong>r submodels are present. Thus, if<br />
one <strong>of</strong> <strong>the</strong> submodels is not present, <strong>the</strong>re must be a mechanism that provides a constant<br />
parametrization <strong>of</strong> its output variables. To this end <strong>the</strong> module ForestBase was <strong>in</strong>troduced,<br />
which conta<strong>in</strong>s always a pseudo-model. At <strong>the</strong> startup <strong>of</strong> FORCLIM, this pseudomodel<br />
declares all <strong>the</strong> <strong>in</strong>put/output variables <strong>of</strong> all <strong>the</strong> potential FORCLIM submodels as<br />
model parameters. Every submodel that is declared <strong>in</strong> ModelWorks subsequently removes<br />
<strong>the</strong> parameters correspond<strong>in</strong>g to its output variables and supplies <strong>the</strong>ir values<br />
based on its dynamics. In case <strong>the</strong> user removes a submodel, ForestBase declares <strong>the</strong> respective<br />
parameters <strong>in</strong> <strong>the</strong> pseudo-model aga<strong>in</strong>. Thus all <strong>the</strong> variables coupl<strong>in</strong>g <strong>the</strong><br />
FORCLIM submodels have always well-def<strong>in</strong>ed values (Fig. 3.13).<br />
The module structure <strong>of</strong> <strong>the</strong> FORCLIM system is shown <strong>in</strong> Fig. 3.14, and <strong>the</strong> matrix <strong>of</strong><br />
module dependencies is given <strong>in</strong> Tab. 3.18. FORCLIM-E and FORCLIM-S are implemented<br />
as one s<strong>in</strong>gle module each. The six modules mak<strong>in</strong>g up FORCLIM-P serve <strong>the</strong><br />
follow<strong>in</strong>g purposes:<br />
FCPBase provides a dynamic list <strong>of</strong> Modula-2 records with variables describ<strong>in</strong>g <strong>the</strong> tree<br />
species, i.e. <strong>the</strong> species-specific growth factors and parameters. A list <strong>of</strong> tree cohorts is<br />
attached to each tree species. Aga<strong>in</strong>, each tree cohort is described by a Modula-2 record<br />
conta<strong>in</strong><strong>in</strong>g <strong>the</strong> cohort-specific state and auxiliary variables. FCPBase also <strong>of</strong>fers procedures<br />
for add<strong>in</strong>g species and cohorts to and delet<strong>in</strong>g <strong>the</strong>m from <strong>the</strong>se lists. Moreover, a<br />
procedure for <strong>the</strong> <strong>in</strong>teractive edit<strong>in</strong>g <strong>of</strong> <strong>the</strong> species parameters is exported.