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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Discussion 177<br />
end <strong>of</strong> <strong>the</strong> 21st century, we may conjecture that mid altitudes <strong>in</strong> <strong>the</strong> European Alps are<br />
likely to undergo m<strong>in</strong>or changes only, whereas subalp<strong>in</strong>e areas and those close to <strong>the</strong> dry<br />
timberl<strong>in</strong>e are likely to undergo drastic changes <strong>of</strong> species composition, <strong>in</strong>clud<strong>in</strong>g forest<br />
dieback phenomena.<br />
These results suggest that <strong>the</strong> prediction <strong>of</strong> <strong>the</strong> species composition <strong>of</strong> near-natural forests<br />
under a changed climate is quite difficult. Hence it would be even more difficult to predict<br />
<strong>the</strong> transient dynamics <strong>of</strong> forest ecosystems <strong>in</strong> response to a transient climatic change<br />
(Schneider & Thompson 1981). The comparison <strong>of</strong> step, ramp, and sigmoid climatic<br />
changes dur<strong>in</strong>g 100 years show that <strong>the</strong> choice <strong>of</strong> <strong>the</strong> transient scenario is not <strong>of</strong> paramount<br />
importance at this temporal scale because <strong>the</strong> anticipated climatic change proceeds<br />
much faster than <strong>the</strong> successional dynamics. Hence, <strong>the</strong> step and ramp scenarios used <strong>in</strong><br />
previous studies (e.g. Solomon 1986, Pastor & Post 1988, Kienast 1991, Fischl<strong>in</strong> et al.<br />
1994, Bugmann & Fischl<strong>in</strong> 1994) constitute a sufficient approximation <strong>of</strong> more detailed<br />
scenarios <strong>of</strong> transient climatic change on <strong>the</strong> timescale <strong>of</strong> 100 years.<br />
7.6 Tools for modell<strong>in</strong>g and simulation<br />
The RAMSES s<strong>of</strong>tware for modell<strong>in</strong>g and simulation (Fischl<strong>in</strong> et al. 1990, Fischl<strong>in</strong> 1991)<br />
proved to be very helpful for becom<strong>in</strong>g familiar with forest gap models <strong>in</strong> <strong>the</strong> first,<br />
explorative phase <strong>of</strong> <strong>the</strong> project. The flexibility it <strong>of</strong>fers for <strong>in</strong>teractively chang<strong>in</strong>g parameters,<br />
monitor<strong>in</strong>g any desired variable, and add<strong>in</strong>g or remov<strong>in</strong>g s<strong>in</strong>gle submodels without<br />
hav<strong>in</strong>g to change <strong>the</strong> code was especially useful <strong>in</strong> that phase. Throughout <strong>the</strong> <strong>the</strong>sis,<br />
work<strong>in</strong>g <strong>in</strong>teractively with <strong>the</strong> user <strong>in</strong>terface <strong>of</strong> ModelWorks (Fischl<strong>in</strong> et al. 1990) was<br />
important. Moreover, <strong>the</strong> ModelWorks experiment mechanism made it possible to program<br />
large simulation experiments as well and to run <strong>the</strong>m <strong>in</strong> a batch-oriented mode on<br />
up to four remote simulation servers at a time. This turned out to be <strong>in</strong>dispensable and<br />
became ever more important towards <strong>the</strong> end <strong>of</strong> this study, especially for perform<strong>in</strong>g <strong>the</strong><br />
analyses presented <strong>in</strong> chapter 5.<br />
The access to <strong>the</strong> high-level programm<strong>in</strong>g language Modula-2 (Wirth 1985) allowed to<br />
split <strong>the</strong> implementation <strong>of</strong> FORCLIM <strong>in</strong>to several modules with well-def<strong>in</strong>ed <strong>in</strong>terfaces.<br />
This made it easy to change s<strong>in</strong>gle features <strong>of</strong> FORCLIM without <strong>the</strong> risk <strong>of</strong> produc<strong>in</strong>g<br />
side effects on o<strong>the</strong>r features. Moreover, <strong>the</strong> Dialog Mach<strong>in</strong>e (Fischl<strong>in</strong> 1986, Fischl<strong>in</strong> &<br />
Ulrich 1987) and Modula-2 made it possible to program a number <strong>of</strong> additional features,<br />
which provided even more flexibility from both <strong>the</strong> modeller's and <strong>the</strong> user's perspective.